Articles | Volume 19, issue 8
Atmos. Chem. Phys., 19, 5331–5347, 2019
https://doi.org/10.5194/acp-19-5331-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Atmos. Chem. Phys., 19, 5331–5347, 2019
https://doi.org/10.5194/acp-19-5331-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article 18 Apr 2019
Research article | 18 Apr 2019
Constraining the aerosol influence on cloud liquid water path
Edward Gryspeerdt et al.
Related authors
Edward Gryspeerdt, Tom Goren, and Tristan W. P. Smith
Atmos. Chem. Phys., 21, 6093–6109, https://doi.org/10.5194/acp-21-6093-2021, https://doi.org/10.5194/acp-21-6093-2021, 2021
Short summary
Short summary
Cloud responses to aerosol are time-sensitive, but this development is rarely observed. This study uses isolated aerosol perturbations from ships to measure this development and shows that macrophysical (width, cloud fraction, detectability) and microphysical (droplet number) properties of ship tracks vary strongly with time since emission, background cloud and meteorological state. This temporal development should be considered when constraining aerosol–cloud interactions with observations.
Johannes Quaas, Antti Arola, Brian Cairns, Matthew Christensen, Hartwig Deneke, Annica M. L. Ekman, Graham Feingold, Ann Fridlind, Edward Gryspeerdt, Otto Hasekamp, Zhanqing Li, Antti Lipponen, Po-Lun Ma, Johannes Mülmenstädt, Athanasios Nenes, Joyce E. Penner, Daniel Rosenfeld, Roland Schrödner, Kenneth Sinclair, Odran Sourdeval, Philip Stier, Matthias Tesche, Bastiaan van Diedenhoven, and Manfred Wendisch
Atmos. Chem. Phys., 20, 15079–15099, https://doi.org/10.5194/acp-20-15079-2020, https://doi.org/10.5194/acp-20-15079-2020, 2020
Short summary
Short summary
Anthropogenic pollution particles – aerosols – serve as cloud condensation nuclei and thus increase cloud droplet concentration and the clouds' reflection of sunlight (a cooling effect on climate). This Twomey effect is poorly constrained by models and requires satellite data for better quantification. The review summarizes the challenges in properly doing so and outlines avenues for progress towards a better use of aerosol retrievals and better retrievals of droplet concentrations.
Edward Gryspeerdt, Johannes Mülmenstädt, Andrew Gettelman, Florent F. Malavelle, Hugh Morrison, David Neubauer, Daniel G. Partridge, Philip Stier, Toshihiko Takemura, Hailong Wang, Minghuai Wang, and Kai Zhang
Atmos. Chem. Phys., 20, 613–623, https://doi.org/10.5194/acp-20-613-2020, https://doi.org/10.5194/acp-20-613-2020, 2020
Short summary
Short summary
Aerosol radiative forcing is a key uncertainty in our understanding of the human forcing of the climate, with much of this uncertainty coming from aerosol impacts on clouds. Observation-based estimates of the radiative forcing are typically smaller than those from global models, but it is not clear if they are more reliable. This work shows how the forcing components in global climate models can be identified, highlighting similarities between the two methods and areas for future investigation.
Johannes Mülmenstädt, Edward Gryspeerdt, Marc Salzmann, Po-Lun Ma, Sudhakar Dipu, and Johannes Quaas
Atmos. Chem. Phys., 19, 15415–15429, https://doi.org/10.5194/acp-19-15415-2019, https://doi.org/10.5194/acp-19-15415-2019, 2019
Short summary
Short summary
The effect of aerosol–cloud interactions (ACIs) on Earth's energy budget continues to be highly uncertain. We decompose the effective radiative forcing by ACIs (ERFaci) into the instantaneous forcing due to anthropogenic increases in the number of cloud droplets and fast responses of cloud properties to the droplet number perturbation in the ECHAM–HAMMOZ aerosol–climate model. This decomposition maps onto the IPCC's Fifth Assessment Report analysis of ERFaci more directly than previous work.
Odran Sourdeval, Edward Gryspeerdt, Martina Krämer, Tom Goren, Julien Delanoë, Armin Afchine, Friederike Hemmer, and Johannes Quaas
Atmos. Chem. Phys., 18, 14327–14350, https://doi.org/10.5194/acp-18-14327-2018, https://doi.org/10.5194/acp-18-14327-2018, 2018
Short summary
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The number concentration of ice crystals (Ni) is a key cloud property that remains very uncertain due to difficulties in determining it using satellites. This lack of global observational constraints limits our ability to constrain this property in models responsible for predicting future climate. This pair of papers fills this gap by showing and analyzing the first rigorously evaluated global climatology of Ni, leading to new information shedding light on the processes that control high clouds.
Edward Gryspeerdt, Odran Sourdeval, Johannes Quaas, Julien Delanoë, Martina Krämer, and Philipp Kühne
Atmos. Chem. Phys., 18, 14351–14370, https://doi.org/10.5194/acp-18-14351-2018, https://doi.org/10.5194/acp-18-14351-2018, 2018
Short summary
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The concentration of ice crystals in a cloud affects both the properties and the life cycle of the cloud. This work uses a new satellite retrieval to investigate controls on the ice crystal concentration at a global scale. Both temperature and vertical wind speed in a cloud have a strong impact on the concentration of ice crystals. The ice crystal number is also related to the aerosol environment; defining this relation opens up new ways to investigate human impacts on clouds and the climate.
Edward Gryspeerdt, Johannes Quaas, Tom Goren, Daniel Klocke, and Matthias Brueck
Atmos. Chem. Phys., 18, 6157–6169, https://doi.org/10.5194/acp-18-6157-2018, https://doi.org/10.5194/acp-18-6157-2018, 2018
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Cirrus clouds can form by a variety of mechanisms, such as orographic uplift, through convective systems or through large-scale rising motions. In this work, an automated classification of cirrus clouds based on satellite and reanalysis data is presented to separate cirrus by these different formation mechanisms. The classification provides information on the ice origin and cloud-scale updraughts that could not be determined using satellite or reanalysis data alone.
Bethan White, Edward Gryspeerdt, Philip Stier, Hugh Morrison, Gregory Thompson, and Zak Kipling
Atmos. Chem. Phys., 17, 12145–12175, https://doi.org/10.5194/acp-17-12145-2017, https://doi.org/10.5194/acp-17-12145-2017, 2017
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Aerosols influence cloud and precipitation by modifying cloud droplet number concentrations (CDNCs). We simulate three different types of convective cloud using two different cloud microphysics parameterisations. The simulated cloud and precipitation depends much more strongly on the choice of microphysics scheme than on CDNC. The uncertainty differs between types of convection. Our results highlight a large uncertainty in cloud and precipitation responses to aerosol in current models.
Nick Schutgens, Svetlana Tsyro, Edward Gryspeerdt, Daisuke Goto, Natalie Weigum, Michael Schulz, and Philip Stier
Atmos. Chem. Phys., 17, 9761–9780, https://doi.org/10.5194/acp-17-9761-2017, https://doi.org/10.5194/acp-17-9761-2017, 2017
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We estimate representativeness errors in observations due to mismatching spatio-temporal sampling, on timescales of hours to a year and length scales of 50 to 200 km, for a variety of observing systems (in situ or remote sensing ground sites, satellites with imagers or lidar, etc.) and develop strategies to reduce them. This study is relevant to the use of observations in constructing satellite L3 products, observational intercomparison and model evaluation.
Duncan Watson-Parris, Nick Schutgens, Nicholas Cook, Zak Kipling, Philip Kershaw, Edward Gryspeerdt, Bryan Lawrence, and Philip Stier
Geosci. Model Dev., 9, 3093–3110, https://doi.org/10.5194/gmd-9-3093-2016, https://doi.org/10.5194/gmd-9-3093-2016, 2016
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In this paper we describe CIS, a new command line tool for the easy visualization, analysis and comparison of a wide variety of gridded and ungridded data sets used in Earth sciences. Users can now use a single tool to not only view plots of satellite, aircraft, station or model data, but also bring them onto the same spatio-temporal sampling. This allows robust, quantitative comparisons to be made easily. CIS is an open-source project and welcomes input from the community.
Nick A. J. Schutgens, Edward Gryspeerdt, Natalie Weigum, Svetlana Tsyro, Daisuke Goto, Michael Schulz, and Philip Stier
Atmos. Chem. Phys., 16, 6335–6353, https://doi.org/10.5194/acp-16-6335-2016, https://doi.org/10.5194/acp-16-6335-2016, 2016
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We show that evaluating global aerosol model data with observations of very different spatial scales (200 vs. 10 km) can lead to large discrepancies, solely due to different spatial sampling. Strategies for reducing these sampling errors are developed and tested using a set of high-resolution model simulations.
E. Gryspeerdt, P. Stier, B. A. White, and Z. Kipling
Atmos. Chem. Phys., 15, 7557–7570, https://doi.org/10.5194/acp-15-7557-2015, https://doi.org/10.5194/acp-15-7557-2015, 2015
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Wet scavenging generates differences between the aerosol properties in clear-sky scenes (observed by satellites) and cloudy scenes, leading to different
aerosol-precipitation relationships in satellite data and global models. Convective systems usually draw in air from clear-sky regions, but global models have difficulty separating this aerosol from the aerosol in cloudy scenes within a model gridbox. This may prevent models from reproducing the observed aerosol-precipitation relationships.
E. Gryspeerdt, P. Stier, and D. G. Partridge
Atmos. Chem. Phys., 14, 9677–9694, https://doi.org/10.5194/acp-14-9677-2014, https://doi.org/10.5194/acp-14-9677-2014, 2014
E. Gryspeerdt, P. Stier, and D. G. Partridge
Atmos. Chem. Phys., 14, 1141–1158, https://doi.org/10.5194/acp-14-1141-2014, https://doi.org/10.5194/acp-14-1141-2014, 2014
Edward Gryspeerdt, Tom Goren, and Tristan W. P. Smith
Atmos. Chem. Phys., 21, 6093–6109, https://doi.org/10.5194/acp-21-6093-2021, https://doi.org/10.5194/acp-21-6093-2021, 2021
Short summary
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Cloud responses to aerosol are time-sensitive, but this development is rarely observed. This study uses isolated aerosol perturbations from ships to measure this development and shows that macrophysical (width, cloud fraction, detectability) and microphysical (droplet number) properties of ship tracks vary strongly with time since emission, background cloud and meteorological state. This temporal development should be considered when constraining aerosol–cloud interactions with observations.
Andrew Gettelman, Chieh-Chieh Chen, and Charles G. Bardeen
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2021-210, https://doi.org/10.5194/acp-2021-210, 2021
Preprint under review for ACP
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The COVID19 pandemic caused significant economic disruption in 2020 and severely impacted air traffic. We use a climate model to evaluate the effect of the reductions in aviation on climate in 2020. Contrails in general warm the planet, and COVID reductions in contrails cooled the land surface in 2020. The timing of reductions in aviation was important and this may change how we think about future effects of contrails.
Sara Bacer, Sylvia C. Sullivan, Odran Sourdeval, Holger Tost, Jos Lelieveld, and Andrea Pozzer
Atmos. Chem. Phys., 21, 1485–1505, https://doi.org/10.5194/acp-21-1485-2021, https://doi.org/10.5194/acp-21-1485-2021, 2021
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We investigate the relative importance of the rates of both microphysical processes and unphysical correction terms that act as sources or sinks of ice crystals in cold clouds. By means of numerical simulations performed with a global chemistry–climate model, we assess the relevance of these rates at global and regional scales. This estimation is of fundamental importance to assign priority to the development of microphysics parameterizations and compare model output with observations.
Johannes Quaas, Antti Arola, Brian Cairns, Matthew Christensen, Hartwig Deneke, Annica M. L. Ekman, Graham Feingold, Ann Fridlind, Edward Gryspeerdt, Otto Hasekamp, Zhanqing Li, Antti Lipponen, Po-Lun Ma, Johannes Mülmenstädt, Athanasios Nenes, Joyce E. Penner, Daniel Rosenfeld, Roland Schrödner, Kenneth Sinclair, Odran Sourdeval, Philip Stier, Matthias Tesche, Bastiaan van Diedenhoven, and Manfred Wendisch
Atmos. Chem. Phys., 20, 15079–15099, https://doi.org/10.5194/acp-20-15079-2020, https://doi.org/10.5194/acp-20-15079-2020, 2020
Short summary
Short summary
Anthropogenic pollution particles – aerosols – serve as cloud condensation nuclei and thus increase cloud droplet concentration and the clouds' reflection of sunlight (a cooling effect on climate). This Twomey effect is poorly constrained by models and requires satellite data for better quantification. The review summarizes the challenges in properly doing so and outlines avenues for progress towards a better use of aerosol retrievals and better retrievals of droplet concentrations.
Jan Kretzschmar, Johannes Stapf, Daniel Klocke, Manfred Wendisch, and Johannes Quaas
Atmos. Chem. Phys., 20, 13145–13165, https://doi.org/10.5194/acp-20-13145-2020, https://doi.org/10.5194/acp-20-13145-2020, 2020
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This study compares simulations with the ICON model at the kilometer scale to airborne radiation and cloud microphysics observations that have been derived during the ACLOUD aircraft campaign around Svalbard, Norway, in May/June 2017. We find an overestimated surface warming effect of clouds compared to the observations in our setup. This bias was reduced by considering subgrid-scale vertical motion in the activation of cloud condensation nuclei in the two-moment microphysical scheme used.
Martina Krämer, Christian Rolf, Nicole Spelten, Armin Afchine, David Fahey, Eric Jensen, Sergey Khaykin, Thomas Kuhn, Paul Lawson, Alexey Lykov, Laura L. Pan, Martin Riese, Andrew Rollins, Fred Stroh, Troy Thornberry, Veronika Wolf, Sarah Woods, Peter Spichtinger, Johannes Quaas, and Odran Sourdeval
Atmos. Chem. Phys., 20, 12569–12608, https://doi.org/10.5194/acp-20-12569-2020, https://doi.org/10.5194/acp-20-12569-2020, 2020
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To improve the representations of cirrus clouds in climate predictions, extended knowledge of their properties and geographical distribution is required. This study presents extensive airborne in situ and satellite remote sensing climatologies of cirrus and humidity, which serve as a guide to cirrus clouds. Further, exemplary radiative characteristics of cirrus types and also in situ observations of tropical tropopause layer cirrus and humidity in the Asian monsoon anticyclone are shown.
Caroline A. Poulsen, Gregory R. McGarragh, Gareth E. Thomas, Martin Stengel, Matthew W. Christensen, Adam C. Povey, Simon R. Proud, Elisa Carboni, Rainer Hollmann, and Roy G. Grainger
Earth Syst. Sci. Data, 12, 2121–2135, https://doi.org/10.5194/essd-12-2121-2020, https://doi.org/10.5194/essd-12-2121-2020, 2020
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We have created a satellite cloud and radiation climatology from the ATSR-2 and AATSR on board ERS-2 and Envisat, respectively, which spans the period 1995–2012. The data set was created using a combination of optimal estimation and neural net techniques. The data set was created as part of the ESA Climate Change Initiative program. The data set has been compared with active CALIOP lidar measurements and compared with MAC-LWP AND CERES-EBAF measurements and is shown to have good performance.
Nicolas Bellouin, Will Davies, Keith P. Shine, Johannes Quaas, Johannes Mülmenstädt, Piers M. Forster, Chris Smith, Lindsay Lee, Leighton Regayre, Guy Brasseur, Natalia Sudarchikova, Idir Bouarar, Olivier Boucher, and Gunnar Myhre
Earth Syst. Sci. Data, 12, 1649–1677, https://doi.org/10.5194/essd-12-1649-2020, https://doi.org/10.5194/essd-12-1649-2020, 2020
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Quantifying the imbalance in the Earth's energy budget caused by human activities is important to understand and predict climate changes. This study presents new estimates of the imbalance caused by changes in atmospheric concentrations of carbon dioxide, methane, ozone, and particles of pollution. Over the period 2003–2017, the overall imbalance has been positive, indicating that the climate system has gained energy and will warm further.
Montserrat Costa-Surós, Odran Sourdeval, Claudia Acquistapace, Holger Baars, Cintia Carbajal Henken, Christa Genz, Jonas Hesemann, Cristofer Jimenez, Marcel König, Jan Kretzschmar, Nils Madenach, Catrin I. Meyer, Roland Schrödner, Patric Seifert, Fabian Senf, Matthias Brueck, Guido Cioni, Jan Frederik Engels, Kerstin Fieg, Ksenia Gorges, Rieke Heinze, Pavan Kumar Siligam, Ulrike Burkhardt, Susanne Crewell, Corinna Hoose, Axel Seifert, Ina Tegen, and Johannes Quaas
Atmos. Chem. Phys., 20, 5657–5678, https://doi.org/10.5194/acp-20-5657-2020, https://doi.org/10.5194/acp-20-5657-2020, 2020
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The impact of anthropogenic aerosols on clouds is a key uncertainty in climate change. This study analyses large-domain simulations with a new high-resolution model to investigate the differences in clouds between 1985 and 2013 comparing multiple observational datasets. The differences in aerosol and in cloud droplet concentrations are clearly detectable. For other quantities, the detection and attribution proved difficult, despite a substantial impact on the Earth's energy budget.
Guy Dagan, Philip Stier, Matthew Christensen, Guido Cioni, Daniel Klocke, and Axel Seifert
Atmos. Chem. Phys., 20, 4523–4544, https://doi.org/10.5194/acp-20-4523-2020, https://doi.org/10.5194/acp-20-4523-2020, 2020
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In order to better understand the physical processes behind aerosol effects on the atmospheric energy budget, we analyse numerical simulations of tropical cloud systems. Two sets of simulations, at different dates during the NARVAL 2 field campaign, are simulated with different dominant cloud modes. Our results demonstrate that under different environmental conditions, the response of the atmospheric energy budget to aerosol perturbation could be different.
Steven J. Abel, Paul A. Barrett, Paquita Zuidema, Jianhao Zhang, Matt Christensen, Fanny Peers, Jonathan W. Taylor, Ian Crawford, Keith N. Bower, and Michael Flynn
Atmos. Chem. Phys., 20, 4059–4084, https://doi.org/10.5194/acp-20-4059-2020, https://doi.org/10.5194/acp-20-4059-2020, 2020
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In situ measurements of a free-tropospheric (FT) biomass burning aerosol plume in contact with the boundary layer inversion overriding a pocket of open cells (POC) and surrounding stratiform cloud are presented. The data highlight the contrasting thermodynamic, aerosol and cloud properties in the two cloud regimes and further demonstrate that the cloud regime plays a key role in regulating the flow of FT aerosols into the boundary layer, which has implications for the aerosol indirect effect.
Claudia Unglaub, Karoline Block, Johannes Mülmenstädt, Odran Sourdeval, and Johannes Quaas
Atmos. Chem. Phys., 20, 2407–2418, https://doi.org/10.5194/acp-20-2407-2020, https://doi.org/10.5194/acp-20-2407-2020, 2020
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In cloud research, it is necessary to classify clouds. The World Meteorological Organization proposes distinguishing stratiform and cumuliform clouds in three altitude layers. The paper explains why previous approaches to classify clouds fail for many applications and proposes a new classification on the basis of new approaches for satellite retrievals to derive cloud-base height, in combination with cloud inhomogeneity. It is demonstrated that this discriminates cloud characteristics well.
Edward Gryspeerdt, Johannes Mülmenstädt, Andrew Gettelman, Florent F. Malavelle, Hugh Morrison, David Neubauer, Daniel G. Partridge, Philip Stier, Toshihiko Takemura, Hailong Wang, Minghuai Wang, and Kai Zhang
Atmos. Chem. Phys., 20, 613–623, https://doi.org/10.5194/acp-20-613-2020, https://doi.org/10.5194/acp-20-613-2020, 2020
Short summary
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Aerosol radiative forcing is a key uncertainty in our understanding of the human forcing of the climate, with much of this uncertainty coming from aerosol impacts on clouds. Observation-based estimates of the radiative forcing are typically smaller than those from global models, but it is not clear if they are more reliable. This work shows how the forcing components in global climate models can be identified, highlighting similarities between the two methods and areas for future investigation.
Martin Stengel, Stefan Stapelberg, Oliver Sus, Stephan Finkensieper, Benjamin Würzler, Daniel Philipp, Rainer Hollmann, Caroline Poulsen, Matthew Christensen, and Gregory McGarragh
Earth Syst. Sci. Data, 12, 41–60, https://doi.org/10.5194/essd-12-41-2020, https://doi.org/10.5194/essd-12-41-2020, 2020
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The Cloud_cci AVHRR-PMv3 dataset contains global, cloud and radiative flux properties covering the period of 1982 to 2016. The properties were retrieved from AVHRR measurements recorded by afternoon satellites of the NOAA POES missions. Validation against CALIOP, BSRN and CERES demonstrates the high quality of the data. The Cloud_cci AVHRR-PMv3 dataset allows for a large variety of climate applications that build on cloud properties, radiative flux properties and/or the link between them.
Johannes Mülmenstädt, Edward Gryspeerdt, Marc Salzmann, Po-Lun Ma, Sudhakar Dipu, and Johannes Quaas
Atmos. Chem. Phys., 19, 15415–15429, https://doi.org/10.5194/acp-19-15415-2019, https://doi.org/10.5194/acp-19-15415-2019, 2019
Short summary
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The effect of aerosol–cloud interactions (ACIs) on Earth's energy budget continues to be highly uncertain. We decompose the effective radiative forcing by ACIs (ERFaci) into the instantaneous forcing due to anthropogenic increases in the number of cloud droplets and fast responses of cloud properties to the droplet number perturbation in the ECHAM–HAMMOZ aerosol–climate model. This decomposition maps onto the IPCC's Fifth Assessment Report analysis of ERFaci more directly than previous work.
Nils Madenach, Cintia Carbajal Henken, René Preusker, Odran Sourdeval, and Jürgen Fischer
Atmos. Chem. Phys., 19, 13535–13546, https://doi.org/10.5194/acp-19-13535-2019, https://doi.org/10.5194/acp-19-13535-2019, 2019
Max Heikenfeld, Peter J. Marinescu, Matthew Christensen, Duncan Watson-Parris, Fabian Senf, Susan C. van den Heever, and Philip Stier
Geosci. Model Dev., 12, 4551–4570, https://doi.org/10.5194/gmd-12-4551-2019, https://doi.org/10.5194/gmd-12-4551-2019, 2019
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We present tobac (Tracking and Object-Based Analysis of Clouds), a newly developed framework for tracking and analysing clouds in different types of datasets. It provides a flexible new way to include the evolution of individual clouds in a wide range of analyses. It is developed as a community project to provide a common basis for the inclusion of existing tracking algorithms and the development of new analyses that involve tracking clouds and other features in geoscientific research.
Jacob Schacht, Bernd Heinold, Johannes Quaas, John Backman, Ribu Cherian, Andre Ehrlich, Andreas Herber, Wan Ting Katty Huang, Yutaka Kondo, Andreas Massling, P. R. Sinha, Bernadett Weinzierl, Marco Zanatta, and Ina Tegen
Atmos. Chem. Phys., 19, 11159–11183, https://doi.org/10.5194/acp-19-11159-2019, https://doi.org/10.5194/acp-19-11159-2019, 2019
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The Arctic is warming faster than the rest of Earth. Black carbon (BC) aerosol contributes to this Arctic amplification by direct and indirect aerosol radiative effects while distributed in air or deposited on snow and ice. The aerosol-climate model ECHAM-HAM is used to estimate direct aerosol radiative effect (DRE). Airborne and near-surface BC measurements are used to evaluate the model and give an uncertainty range for the burden and DRE of Arctic BC caused by different emission inventories.
Lei Lin, Andrew Gettelman, Yangyang Xu, Chenglai Wu, Zhili Wang, Nan Rosenbloom, Susan C. Bates, and Wenjie Dong
Geosci. Model Dev., 12, 3773–3793, https://doi.org/10.5194/gmd-12-3773-2019, https://doi.org/10.5194/gmd-12-3773-2019, 2019
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Here we evaluate the performance of the Community Atmosphere Model version 6 (CAM6) released in 2018, with the default 1º horizontal resolution and a higher-resolution simulation (approximately 0.25º), against various precipitation observational datasets over Asia. With the prognostic treatment of precipitation processes (which is missing in CAM5) and the new microphysics module, CAM6 is able to better simulate climatological mean and extreme precipitation over Asia.
Jan Kretzschmar, Marc Salzmann, Johannes Mülmenstädt, and Johannes Quaas
Atmos. Chem. Phys., 19, 10571–10589, https://doi.org/10.5194/acp-19-10571-2019, https://doi.org/10.5194/acp-19-10571-2019, 2019
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This study aims to explore Arctic cloud properties in the atmospheric circulation model ECHAM6. We compare cloud properties in the model to satellite observations using a satellite simulator and show that ECHAM6 overestimates low-level liquid-containing clouds. In sensitivity studies, we show that this bias can be related to cloud microphysics and surface fluxes.
Hailing Jia, Xiaoyan Ma, Johannes Quaas, Yan Yin, and Tom Qiu
Atmos. Chem. Phys., 19, 8879–8896, https://doi.org/10.5194/acp-19-8879-2019, https://doi.org/10.5194/acp-19-8879-2019, 2019
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We systematically assess how and to what extent satellite retrieval biases may affect correlations, as well as explore the underlying physical mechanisms. It is noted that the retrieval biases of both cloud and aerosol can result in a serious overestimation of the slope of CER–AI. Positive correlations more likely to occur in the case of drier cloud top and stronger turbulence in clouds, implying entrainment mixing might be a possible physical interpretation for such a positive CER–AI slope.
Christoph Böhm, Odran Sourdeval, Johannes Mülmenstädt, Johannes Quaas, and Susanne Crewell
Atmos. Meas. Tech., 12, 1841–1860, https://doi.org/10.5194/amt-12-1841-2019, https://doi.org/10.5194/amt-12-1841-2019, 2019
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The cloud base height (CBH) is important for air traffic, for describing the energy budget of the Earth and for other applications. Ground-based CBH measurements are only available for individual sites and mostly limited to land. Satellites are a powerful tool for global coverage. While the cloud top height is derived operationally, the derivation of CBH from space is more difficult as the clouds hide their base. Here, we present a method to retrieve the CBH from multi-angle satellite data.
Johannes Mülmenstädt, Odran Sourdeval, David S. Henderson, Tristan S. L'Ecuyer, Claudia Unglaub, Leonore Jungandreas, Christoph Böhm, Lynn M. Russell, and Johannes Quaas
Earth Syst. Sci. Data, 10, 2279–2293, https://doi.org/10.5194/essd-10-2279-2018, https://doi.org/10.5194/essd-10-2279-2018, 2018
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One of the key pieces of information about a cloud is how high its base is. Unlike cloud top, cloud base is hard to observe from a satellite perspective – the cloud blocks the view. But without using satellites, it is difficult to compile global datasets. Here we describe how we worked around the limitations of a cloud-detecting laser satellite to observe global cloud base heights. This dataset will expand our knowledge of the cloudy atmosphere and its interaction with the planetary surface.
Odran Sourdeval, Edward Gryspeerdt, Martina Krämer, Tom Goren, Julien Delanoë, Armin Afchine, Friederike Hemmer, and Johannes Quaas
Atmos. Chem. Phys., 18, 14327–14350, https://doi.org/10.5194/acp-18-14327-2018, https://doi.org/10.5194/acp-18-14327-2018, 2018
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The number concentration of ice crystals (Ni) is a key cloud property that remains very uncertain due to difficulties in determining it using satellites. This lack of global observational constraints limits our ability to constrain this property in models responsible for predicting future climate. This pair of papers fills this gap by showing and analyzing the first rigorously evaluated global climatology of Ni, leading to new information shedding light on the processes that control high clouds.
Edward Gryspeerdt, Odran Sourdeval, Johannes Quaas, Julien Delanoë, Martina Krämer, and Philipp Kühne
Atmos. Chem. Phys., 18, 14351–14370, https://doi.org/10.5194/acp-18-14351-2018, https://doi.org/10.5194/acp-18-14351-2018, 2018
Short summary
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The concentration of ice crystals in a cloud affects both the properties and the life cycle of the cloud. This work uses a new satellite retrieval to investigate controls on the ice crystal concentration at a global scale. Both temperature and vertical wind speed in a cloud have a strong impact on the concentration of ice crystals. The ice crystal number is also related to the aerosol environment; defining this relation opens up new ways to investigate human impacts on clouds and the climate.
Daniel P. Grosvenor, Odran Sourdeval, and Robert Wood
Atmos. Meas. Tech., 11, 4273–4289, https://doi.org/10.5194/amt-11-4273-2018, https://doi.org/10.5194/amt-11-4273-2018, 2018
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We provide a parameterized correction to the retrieval of cloud effective radius from satellite instruments to account for the assumption that the retrieved value is representative of that at cloud top, whereas in reality it is representative of that lower down. The error leads to errors (which we quantify) in the retrieved cloud droplet concentrations of up to 38 % for stratocumulus regions and also to liquid water path errors, both of which can be corrected using our parameterizations.
Paul Petersik, Marc Salzmann, Jan Kretzschmar, Ribu Cherian, Daniel Mewes, and Johannes Quaas
Atmos. Chem. Phys., 18, 8589–8599, https://doi.org/10.5194/acp-18-8589-2018, https://doi.org/10.5194/acp-18-8589-2018, 2018
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Our study presents the first estimate of RFari using a global atmospheric model with a parameterization for subgrid-scale variability in RH that is consistent with the assumptions in the model. We find that the revision has a strong influence on the simulated radiative forcing (~ 31 %). In addition, we examine its effects on optical properties of the atmosphere and find an increase in AOD by about 7.8 %.
Oliver Sus, Martin Stengel, Stefan Stapelberg, Gregory McGarragh, Caroline Poulsen, Adam C. Povey, Cornelia Schlundt, Gareth Thomas, Matthew Christensen, Simon Proud, Matthias Jerg, Roy Grainger, and Rainer Hollmann
Atmos. Meas. Tech., 11, 3373–3396, https://doi.org/10.5194/amt-11-3373-2018, https://doi.org/10.5194/amt-11-3373-2018, 2018
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This paper presents a new cloud detection and classification framework, CC4CL. It applies a sophisticated optimal estimation method to derive cloud variables from satellite data of various polar-orbiting platforms and sensors (AVHRR, MODIS, AATSR). CC4CL provides explicit uncertainty quantification and long-term consistency for decadal timeseries at various spatial resolutions. We analysed 5 case studies to show that cloud height estimates are very realistic unless optically thin clouds overlap.
Gregory R. McGarragh, Caroline A. Poulsen, Gareth E. Thomas, Adam C. Povey, Oliver Sus, Stefan Stapelberg, Cornelia Schlundt, Simon Proud, Matthew W. Christensen, Martin Stengel, Rainer Hollmann, and Roy G. Grainger
Atmos. Meas. Tech., 11, 3397–3431, https://doi.org/10.5194/amt-11-3397-2018, https://doi.org/10.5194/amt-11-3397-2018, 2018
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Satellites are vital for measuring cloud properties necessary for climate prediction studies. We present a method to retrieve cloud properties from satellite based radiometric measurements. The methodology employed is known as optimal estimation and belongs in the class of statistical inversion methods based on Bayes' theorem. We show, through theoretical retrieval simulations, that the solution is stable and accurate to within 10–20% depending on cloud thickness.
Edward Gryspeerdt, Johannes Quaas, Tom Goren, Daniel Klocke, and Matthias Brueck
Atmos. Chem. Phys., 18, 6157–6169, https://doi.org/10.5194/acp-18-6157-2018, https://doi.org/10.5194/acp-18-6157-2018, 2018
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Cirrus clouds can form by a variety of mechanisms, such as orographic uplift, through convective systems or through large-scale rising motions. In this work, an automated classification of cirrus clouds based on satellite and reanalysis data is presented to separate cirrus by these different formation mechanisms. The classification provides information on the ice origin and cloud-scale updraughts that could not be determined using satellite or reanalysis data alone.
Peter A. Bogenschutz, Andrew Gettelman, Cecile Hannay, Vincent E. Larson, Richard B. Neale, Cheryl Craig, and Chih-Chieh Chen
Geosci. Model Dev., 11, 235–255, https://doi.org/10.5194/gmd-11-235-2018, https://doi.org/10.5194/gmd-11-235-2018, 2018
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This paper compares results of developmental versions of a widely used climate model. The simulations only differ in the choice of how to model the sub-grid-scale physics in the atmospheric model. This work is novel because it is the first time that a particular physics option has been tested in a fully coupled climate model. Here, we demonstrate that this physics option has the ability to produce credible coupled climate simulations, with improved metrics in certain fields.
Martin Stengel, Stefan Stapelberg, Oliver Sus, Cornelia Schlundt, Caroline Poulsen, Gareth Thomas, Matthew Christensen, Cintia Carbajal Henken, Rene Preusker, Jürgen Fischer, Abhay Devasthale, Ulrika Willén, Karl-Göran Karlsson, Gregory R. McGarragh, Simon Proud, Adam C. Povey, Roy G. Grainger, Jan Fokke Meirink, Artem Feofilov, Ralf Bennartz, Jedrzej S. Bojanowski, and Rainer Hollmann
Earth Syst. Sci. Data, 9, 881–904, https://doi.org/10.5194/essd-9-881-2017, https://doi.org/10.5194/essd-9-881-2017, 2017
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We present new cloud property datasets based on measurements from the passive imaging satellite sensors AVHRR, MODIS, ATSR2, AATSR and MERIS. Retrieval systems were developed that include cloud detection and cloud typing followed by optimal estimation retrievals of cloud properties (e.g. cloud-top pressure, effective radius, optical thickness, water path). Special features of all datasets are spectral consistency and rigorous uncertainty propagation from pixel-level data to monthly properties.
Matthew W. Christensen, David Neubauer, Caroline A. Poulsen, Gareth E. Thomas, Gregory R. McGarragh, Adam C. Povey, Simon R. Proud, and Roy G. Grainger
Atmos. Chem. Phys., 17, 13151–13164, https://doi.org/10.5194/acp-17-13151-2017, https://doi.org/10.5194/acp-17-13151-2017, 2017
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The cloud-aerosol pairing algorithm (CAPA) is developed to quantify the impact of near-cloud aerosol retrievals on satellite-based aerosol–cloud statistical relationships. We find that previous satellite-based radiative forcing estimates of aerosol–cloud interactions represented in key climate reports are likely exaggerated by up to 50 % due to including retrieval artefacts in the aerosols located near clouds. It is demonstrated that this retrieval artefact can be corrected in current products.
David Neubauer, Matthew W. Christensen, Caroline A. Poulsen, and Ulrike Lohmann
Atmos. Chem. Phys., 17, 13165–13185, https://doi.org/10.5194/acp-17-13165-2017, https://doi.org/10.5194/acp-17-13165-2017, 2017
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When aerosol particles take up water their number may seem to be increased optically. However if aerosol particles are removed by precipitation (formation) their numbers will decrease. We applied methods to account for such effects in model and satellite data to analyse the change in cloud properties by changes in aerosol particle number. The agreement of model and satellite data improves when these effects are accounted for.
Bethan White, Edward Gryspeerdt, Philip Stier, Hugh Morrison, Gregory Thompson, and Zak Kipling
Atmos. Chem. Phys., 17, 12145–12175, https://doi.org/10.5194/acp-17-12145-2017, https://doi.org/10.5194/acp-17-12145-2017, 2017
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Aerosols influence cloud and precipitation by modifying cloud droplet number concentrations (CDNCs). We simulate three different types of convective cloud using two different cloud microphysics parameterisations. The simulated cloud and precipitation depends much more strongly on the choice of microphysics scheme than on CDNC. The uncertainty differs between types of convection. Our results highlight a large uncertainty in cloud and precipitation responses to aerosol in current models.
Nick Schutgens, Svetlana Tsyro, Edward Gryspeerdt, Daisuke Goto, Natalie Weigum, Michael Schulz, and Philip Stier
Atmos. Chem. Phys., 17, 9761–9780, https://doi.org/10.5194/acp-17-9761-2017, https://doi.org/10.5194/acp-17-9761-2017, 2017
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We estimate representativeness errors in observations due to mismatching spatio-temporal sampling, on timescales of hours to a year and length scales of 50 to 200 km, for a variety of observing systems (in situ or remote sensing ground sites, satellites with imagers or lidar, etc.) and develop strategies to reduce them. This study is relevant to the use of observations in constructing satellite L3 products, observational intercomparison and model evaluation.
Sudhakar Dipu, Johannes Quaas, Ralf Wolke, Jens Stoll, Andreas Mühlbauer, Odran Sourdeval, Marc Salzmann, Bernd Heinold, and Ina Tegen
Geosci. Model Dev., 10, 2231–2246, https://doi.org/10.5194/gmd-10-2231-2017, https://doi.org/10.5194/gmd-10-2231-2017, 2017
Chenglai Wu, Xiaohong Liu, Minghui Diao, Kai Zhang, Andrew Gettelman, Zheng Lu, Joyce E. Penner, and Zhaohui Lin
Atmos. Chem. Phys., 17, 4731–4749, https://doi.org/10.5194/acp-17-4731-2017, https://doi.org/10.5194/acp-17-4731-2017, 2017
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This study utilizes a novel approach to directly compare the CAM5-simulated cloud macro- and microphysics with the collocated HIPPO observations for the period of 2009 to 2011. The model cannot capture the large spatial variabilities of observed RH, which is responsible for much of the model missing low-level warm clouds. A large portion of the RH bias results from the discrepancy in water vapor. The model underestimates the observed number concentration and ice water content.
Andrew Gettelman, Chih-Chieh Chen, Mark Z. Jacobson, Mary A. Cameron, Donald J. Wuebbles, and Arezoo Khodayari
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-218, https://doi.org/10.5194/acp-2017-218, 2017
Revised manuscript not accepted
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Aviation emissions create several impacts on climate. Condensation trails (contrails) are aviation produced cirrus clouds. Aircraft also emit aerosols, including soot (black carbon) and sulfate. Analyses of the climate effects of 2050 aviation emissions have been conducted with two coupled Chemistry Climate Models (CCMs) including experiments with coupled ocean models.
Piyushkumar N. Patel, Johannes Quaas, and Raj Kumar
Atmos. Chem. Phys., 17, 3687–3698, https://doi.org/10.5194/acp-17-3687-2017, https://doi.org/10.5194/acp-17-3687-2017, 2017
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Radiative forcing by aerosol–cloud interactions (RFaci) remains highly uncertain and difficult to quantify on the basis of current knowledge. The present study reassesses the estimated RFaci by using a new statistical fitting approach, which improves the quantification of RFaci with less uncertainty. The present work helps to improve the parameterisation of RFaci in the present climate model.
Gunnar Myhre, Wenche Aas, Ribu Cherian, William Collins, Greg Faluvegi, Mark Flanner, Piers Forster, Øivind Hodnebrog, Zbigniew Klimont, Marianne T. Lund, Johannes Mülmenstädt, Cathrine Lund Myhre, Dirk Olivié, Michael Prather, Johannes Quaas, Bjørn H. Samset, Jordan L. Schnell, Michael Schulz, Drew Shindell, Ragnhild B. Skeie, Toshihiko Takemura, and Svetlana Tsyro
Atmos. Chem. Phys., 17, 2709–2720, https://doi.org/10.5194/acp-17-2709-2017, https://doi.org/10.5194/acp-17-2709-2017, 2017
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Over the past decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990–2015, as simulated by seven global atmospheric composition models. The global mean radiative forcing is more strongly positive than reported in IPCC AR5.
Nicolas Bellouin, Laura Baker, Øivind Hodnebrog, Dirk Olivié, Ribu Cherian, Claire Macintosh, Bjørn Samset, Anna Esteve, Borgar Aamaas, Johannes Quaas, and Gunnar Myhre
Atmos. Chem. Phys., 16, 13885–13910, https://doi.org/10.5194/acp-16-13885-2016, https://doi.org/10.5194/acp-16-13885-2016, 2016
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This study uses global climate models to quantify how strongly man-made emissions of selected pollutants modify the energy budget of the Earth. The pollutants studied interact directly and indirectly with sunlight and terrestrial radiation and remain a relatively short time in the atmosphere, leading to regional and seasonal variations in their impacts. This new data set is useful to compare the potential climate impacts of different pollutants in support of policies to reduce climate change.
Duncan Watson-Parris, Nick Schutgens, Nicholas Cook, Zak Kipling, Philip Kershaw, Edward Gryspeerdt, Bryan Lawrence, and Philip Stier
Geosci. Model Dev., 9, 3093–3110, https://doi.org/10.5194/gmd-9-3093-2016, https://doi.org/10.5194/gmd-9-3093-2016, 2016
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In this paper we describe CIS, a new command line tool for the easy visualization, analysis and comparison of a wide variety of gridded and ungridded data sets used in Earth sciences. Users can now use a single tool to not only view plots of satellite, aircraft, station or model data, but also bring them onto the same spatio-temporal sampling. This allows robust, quantitative comparisons to be made easily. CIS is an open-source project and welcomes input from the community.
B. Quennehen, J.-C. Raut, K. S. Law, N. Daskalakis, G. Ancellet, C. Clerbaux, S.-W. Kim, M. T. Lund, G. Myhre, D. J. L. Olivié, S. Safieddine, R. B. Skeie, J. L. Thomas, S. Tsyro, A. Bazureau, N. Bellouin, M. Hu, M. Kanakidou, Z. Klimont, K. Kupiainen, S. Myriokefalitakis, J. Quaas, S. T. Rumbold, M. Schulz, R. Cherian, A. Shimizu, J. Wang, S.-C. Yoon, and T. Zhu
Atmos. Chem. Phys., 16, 10765–10792, https://doi.org/10.5194/acp-16-10765-2016, https://doi.org/10.5194/acp-16-10765-2016, 2016
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This paper evaluates the ability of six global models and one regional model in reproducing short-lived pollutants (defined here as ozone and its precursors, aerosols and black carbon) concentrations over Asia using satellite, ground-based and airborne observations.
Key findings are that models homogeneously reproduce the trace gas observations although nitrous oxides are underestimated, whereas the aerosol distributions are heterogeneously reproduced, implicating important uncertainties.
Chih-Chieh Chen and Andrew Gettelman
Atmos. Chem. Phys., 16, 7317–7333, https://doi.org/10.5194/acp-16-7317-2016, https://doi.org/10.5194/acp-16-7317-2016, 2016
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The impact of aviation emissions through 2050 is simulated by a comprehensive global climate model. Four different future emission scenarios of the same flight tracks are considered. The results reveal that the global radiative forcing of contrail cirrus is positive and can increase by a factor of 7 in 2050 from the 2006 level. The aviation aerosols can produce negative forcing, mainly over the oceans, and increase by a factor of 4 in 2050 from the 2006 level.
Nick A. J. Schutgens, Edward Gryspeerdt, Natalie Weigum, Svetlana Tsyro, Daisuke Goto, Michael Schulz, and Philip Stier
Atmos. Chem. Phys., 16, 6335–6353, https://doi.org/10.5194/acp-16-6335-2016, https://doi.org/10.5194/acp-16-6335-2016, 2016
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We show that evaluating global aerosol model data with observations of very different spatial scales (200 vs. 10 km) can lead to large discrepancies, solely due to different spatial sampling. Strategies for reducing these sampling errors are developed and tested using a set of high-resolution model simulations.
Shipeng Zhang, Minghuai Wang, Steven J. Ghan, Aijun Ding, Hailong Wang, Kai Zhang, David Neubauer, Ulrike Lohmann, Sylvaine Ferrachat, Toshihiko Takeamura, Andrew Gettelman, Hugh Morrison, Yunha Lee, Drew T. Shindell, Daniel G. Partridge, Philip Stier, Zak Kipling, and Congbin Fu
Atmos. Chem. Phys., 16, 2765–2783, https://doi.org/10.5194/acp-16-2765-2016, https://doi.org/10.5194/acp-16-2765-2016, 2016
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The variation of aerosol indirect effects (AIE) in several climate models is investigated across different dynamical regimes. Regimes with strong large-scale ascent are shown to be as important as stratocumulus regimes in studying AIE. AIE over regions with high monthly large-scale surface precipitation rate contributes the most to the total aerosol indirect forcing. These results point to the need to reduce the uncertainty in AIE in different dynamical regimes.
K. Thayer-Calder, A. Gettelman, C. Craig, S. Goldhaber, P. A. Bogenschutz, C.-C. Chen, H. Morrison, J. Höft, E. Raut, B. M. Griffin, J. K. Weber, V. E. Larson, M. C. Wyant, M. Wang, Z. Guo, and S. J. Ghan
Geosci. Model Dev., 8, 3801–3821, https://doi.org/10.5194/gmd-8-3801-2015, https://doi.org/10.5194/gmd-8-3801-2015, 2015
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This study evaluates a unified cloud parameterization and a Monte Carlo microphysics interface that is implemented in CAM v5.3. We show mean climate and tropical variability results from global simulations. The model has a degradation in precipitation skill but improvements in shortwave cloud forcing, liquid water path, long-wave cloud forcing, precipitable water, and tropical wave simulation. We also show estimation of computational expense and sensitivity to number of subcolumns.
A. Gettelman
Atmos. Chem. Phys., 15, 12397–12411, https://doi.org/10.5194/acp-15-12397-2015, https://doi.org/10.5194/acp-15-12397-2015, 2015
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Aerosols affect cloud properties, and the radiative effects of clouds. Human emissions of aerosol particles and precursors may alter the radiative effects of clouds. This is generally a cooling effect that offsets other warming effects of human emissions of gases. Simulating these aerosol effects on clouds are highly dependent on the formulation of the microphysical (cloud droplet scale) processes. This work uses model simulations to show these effects are large, and depend on certain processes.
A. Stohl, B. Aamaas, M. Amann, L. H. Baker, N. Bellouin, T. K. Berntsen, O. Boucher, R. Cherian, W. Collins, N. Daskalakis, M. Dusinska, S. Eckhardt, J. S. Fuglestvedt, M. Harju, C. Heyes, Ø. Hodnebrog, J. Hao, U. Im, M. Kanakidou, Z. Klimont, K. Kupiainen, K. S. Law, M. T. Lund, R. Maas, C. R. MacIntosh, G. Myhre, S. Myriokefalitakis, D. Olivié, J. Quaas, B. Quennehen, J.-C. Raut, S. T. Rumbold, B. H. Samset, M. Schulz, Ø. Seland, K. P. Shine, R. B. Skeie, S. Wang, K. E. Yttri, and T. Zhu
Atmos. Chem. Phys., 15, 10529–10566, https://doi.org/10.5194/acp-15-10529-2015, https://doi.org/10.5194/acp-15-10529-2015, 2015
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This paper presents a summary of the findings of the ECLIPSE EU project. The project has investigated the climate and air quality impacts of short-lived climate pollutants (especially methane, ozone, aerosols) and has designed a global mitigation strategy that maximizes co-benefits between air quality and climate policy. Transient climate model simulations allowed quantifying the impacts on temperature (e.g., reduction in global warming by 0.22K for the decade 2041-2050) and precipitation.
V. N. Aswathy, O. Boucher, M. Quaas, U. Niemeier, H. Muri, J. Mülmenstädt, and J. Quaas
Atmos. Chem. Phys., 15, 9593–9610, https://doi.org/10.5194/acp-15-9593-2015, https://doi.org/10.5194/acp-15-9593-2015, 2015
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Simulations conducted in the GeoMIP and IMPLICC model intercomparison studies for climate engineering by stratospheric sulfate injection and marine cloud brightening via sea salt are analysed and compared to the reference scenario RCP4.5. The focus is on extremes in surface temperature and precipitation. It is found that the extreme changes mostly follow the mean changes and that extremes are also in general well mitigated, except for in polar regions.
S. Eckhardt, B. Quennehen, D. J. L. Olivié, T. K. Berntsen, R. Cherian, J. H. Christensen, W. Collins, S. Crepinsek, N. Daskalakis, M. Flanner, A. Herber, C. Heyes, Ø. Hodnebrog, L. Huang, M. Kanakidou, Z. Klimont, J. Langner, K. S. Law, M. T. Lund, R. Mahmood, A. Massling, S. Myriokefalitakis, I. E. Nielsen, J. K. Nøjgaard, J. Quaas, P. K. Quinn, J.-C. Raut, S. T. Rumbold, M. Schulz, S. Sharma, R. B. Skeie, H. Skov, T. Uttal, K. von Salzen, and A. Stohl
Atmos. Chem. Phys., 15, 9413–9433, https://doi.org/10.5194/acp-15-9413-2015, https://doi.org/10.5194/acp-15-9413-2015, 2015
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The concentrations of sulfate, black carbon and other aerosols in the Arctic are characterized by high values in late winter and spring (so-called Arctic Haze) and low values in summer. Models have long been struggling to capture this seasonality. In this study, we evaluate sulfate and BC concentrations from different updated models and emissions against a comprehensive pan-Arctic measurement data set. We find that the models improved but still struggle to get the maximum concentrations.
L. H. Baker, W. J. Collins, D. J. L. Olivié, R. Cherian, Ø. Hodnebrog, G. Myhre, and J. Quaas
Atmos. Chem. Phys., 15, 8201–8216, https://doi.org/10.5194/acp-15-8201-2015, https://doi.org/10.5194/acp-15-8201-2015, 2015
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We investigate the impact of removing land-based anthropogenic emissions of three aerosol species, using four fully-coupled atmosphere-ocean global climate models. Removing SO2 emissions leads to warming globally, strongest in the Northern Hemisphere (NH), and an increase in NH precipitation. Organic and black carbon (OC, BC) have a weaker impact, and less certainty on the response; OC (BC) removal shows a weak overall warming (cooling), and both show small increases in precipitation globally.
E. Gryspeerdt, P. Stier, B. A. White, and Z. Kipling
Atmos. Chem. Phys., 15, 7557–7570, https://doi.org/10.5194/acp-15-7557-2015, https://doi.org/10.5194/acp-15-7557-2015, 2015
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Wet scavenging generates differences between the aerosol properties in clear-sky scenes (observed by satellites) and cloudy scenes, leading to different
aerosol-precipitation relationships in satellite data and global models. Convective systems usually draw in air from clear-sky regions, but global models have difficulty separating this aerosol from the aerosol in cloudy scenes within a model gridbox. This may prevent models from reproducing the observed aerosol-precipitation relationships.
T. Eidhammer, H. Morrison, A. Bansemer, A. Gettelman, and A. J. Heymsfield
Atmos. Chem. Phys., 14, 10103–10118, https://doi.org/10.5194/acp-14-10103-2014, https://doi.org/10.5194/acp-14-10103-2014, 2014
E. Gryspeerdt, P. Stier, and D. G. Partridge
Atmos. Chem. Phys., 14, 9677–9694, https://doi.org/10.5194/acp-14-9677-2014, https://doi.org/10.5194/acp-14-9677-2014, 2014
M. S. Johnston, S. Eliasson, P. Eriksson, R. M. Forbes, A. Gettelman, P. Räisänen, and M. D. Zelinka
Atmos. Chem. Phys., 14, 8701–8721, https://doi.org/10.5194/acp-14-8701-2014, https://doi.org/10.5194/acp-14-8701-2014, 2014
D. Barahona, A. Molod, J. Bacmeister, A. Nenes, A. Gettelman, H. Morrison, V. Phillips, and A. Eichmann
Geosci. Model Dev., 7, 1733–1766, https://doi.org/10.5194/gmd-7-1733-2014, https://doi.org/10.5194/gmd-7-1733-2014, 2014
E. Gryspeerdt, P. Stier, and D. G. Partridge
Atmos. Chem. Phys., 14, 1141–1158, https://doi.org/10.5194/acp-14-1141-2014, https://doi.org/10.5194/acp-14-1141-2014, 2014
C.-C. Chen and A. Gettelman
Atmos. Chem. Phys., 13, 12525–12536, https://doi.org/10.5194/acp-13-12525-2013, https://doi.org/10.5194/acp-13-12525-2013, 2013
A. Gettelman, H. Morrison, C. R. Terai, and R. Wood
Atmos. Chem. Phys., 13, 9855–9867, https://doi.org/10.5194/acp-13-9855-2013, https://doi.org/10.5194/acp-13-9855-2013, 2013
O. Sourdeval, L. C. -Labonnote, G. Brogniez, O. Jourdan, J. Pelon, and A. Garnier
Atmos. Chem. Phys., 13, 8229–8244, https://doi.org/10.5194/acp-13-8229-2013, https://doi.org/10.5194/acp-13-8229-2013, 2013
N. Bellouin, J. Quaas, J.-J. Morcrette, and O. Boucher
Atmos. Chem. Phys., 13, 2045–2062, https://doi.org/10.5194/acp-13-2045-2013, https://doi.org/10.5194/acp-13-2045-2013, 2013
Related subject area
Subject: Clouds and Precipitation | Research Activity: Remote Sensing | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)
Observing the timescales of aerosol–cloud interactions in snapshot satellite images
Potential impact of aerosols on convective clouds revealed by Himawari-8 observations over different terrain types in eastern China
How frequent is natural cloud seeding from ice cloud layers ( < −35 °C) over Switzerland?
Processes contributing to cloud dissipation and formation events on the North Slope of Alaska
Characterisation and surface radiative impact of Arctic low clouds from the IAOOS field experiment
A-Train estimates of the sensitivity of the cloud-to-rainwater ratio to cloud size, relative humidity, and aerosols
Ice injected into the tropopause by deep convection – Part 2: Over the Maritime Continent
3D radiative heating of tropical upper tropospheric cloud systems derived from synergistic A-Train observations and machine learning
The potential of increasing man-made air pollution to reduce rainfall over southern West Africa
The dual-field-of-view polarization lidar technique: a new concept in monitoring aerosol effects in liquid-water clouds – theoretical framework
The dual-field-of-view polarization lidar technique: a new concept in monitoring aerosol effects in liquid-water clouds – case studies
Constraining the Twomey effect from satellite observations: issues and perspectives
Microphysical properties of three types of snow clouds: implication for satellite snowfall retrievals
Properties of ice cloud over Beijing from surface Ka-band radar observations during 2014–2017
Linkage among ice crystal microphysics, mesoscale dynamics, and cloud and precipitation structures revealed by collocated microwave radiometer and multifrequency radar observations
Possible mechanisms of summer cirrus clouds over the Tibetan Plateau
Lidar observations of Cirrus clouds at Palau island (7°33′ N, 134°48′ E)
Mid-level clouds are frequent above the southeast Atlantic stratocumulus clouds
Towards the connection between snow microphysics and melting layer: insights from multifrequency and dual-polarization radar observations during BAECC
Cloud phase characteristics over Southeast Asia from A-Train satellite observations
Cloud regimes over the Amazon Basin: perspectives from the GoAmazon2014/5 campaign
Microphysics and dynamics of snowfall associated with a warm conveyor belt over Korea
Linking large-scale circulation patterns to low-cloud properties
Quantifying cloud adjustments and the radiative forcing due to aerosol–cloud interactions in satellite observations of warm marine clouds
Small-scale structure of thermodynamic phase in Arctic mixed-phase clouds observed by airborne remote sensing during a cold air outbreak and a warm air advection event
The influence of water vapor anomalies on clouds and their radiative effect at Ny-Ålesund
Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes
Deconvolution of boundary layer depth and aerosol constraints on cloud water path in subtropical stratocumulus decks
Investigation of aerosol–cloud interactions under different absorptive aerosol regimes using Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) ground-based measurements
Low-level mixed-phase clouds in a complex Arctic environment
Synoptic-scale controls of fog and low-cloud variability in the Namib Desert
A new classification of satellite-derived liquid water cloud regimes at cloud scale
The day-to-day co-variability between mineral dust and cloud glaciation: a proxy for heterogeneous freezing
Retrieval of the vertical evolution of the cloud effective radius from the Chinese FY-4 (Feng Yun 4) next-generation geostationary satellites
The role of spring dry zonal advection in summer drought onset over the US Great Plains
Diurnal variation of high-level clouds from the synergy of AIRS and IASI space-borne infrared sounders
Analysis and quantification of ENSO-linked changes in the tropical Atlantic cloud vertical distribution using 14 years of MODIS observations
Variability in vertical structure of precipitation with sea surface temperature over the Arabian Sea and the Bay of Bengal as inferred by Tropical Rainfall Measuring Mission precipitation radar measurements
Spatial and temporal variability of snowfall over Greenland from CloudSat observations
Cloud responses to climate variability over the extratropical oceans as observed by MISR and MODIS
Antarctic clouds, supercooled liquid water and mixed phase, investigated with DARDAR: geographical and seasonal variations
Ice injected into the tropopause by deep convection – Part 1: In the austral convective tropics
Quantifying variations in shortwave aerosol–cloud–radiation interactions using local meteorology and cloud state constraints
Rapid ice aggregation process revealed through triple-wavelength Doppler spectrum radar analysis
Northern Hemisphere contrail properties derived from Terra and Aqua MODIS data for 2006 and 2012
Lidar measurements of thin laminations within Arctic clouds
Spatiotemporal dynamics of fog and low clouds in the Namib unveiled with ground- and space-based observations
Statistics on clouds and their relation to thermodynamic conditions at Ny-Ålesund using ground-based sensor synergy
Evaluating models' response of tropical low clouds to SST forcings using CALIPSO observations
Evaluating solar radiation forecast uncertainty
Edward Gryspeerdt, Tom Goren, and Tristan W. P. Smith
Atmos. Chem. Phys., 21, 6093–6109, https://doi.org/10.5194/acp-21-6093-2021, https://doi.org/10.5194/acp-21-6093-2021, 2021
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Cloud responses to aerosol are time-sensitive, but this development is rarely observed. This study uses isolated aerosol perturbations from ships to measure this development and shows that macrophysical (width, cloud fraction, detectability) and microphysical (droplet number) properties of ship tracks vary strongly with time since emission, background cloud and meteorological state. This temporal development should be considered when constraining aerosol–cloud interactions with observations.
Tianmeng Chen, Zhanqing Li, Ralph A. Kahn, Chuanfeng Zhao, Daniel Rosenfeld, Jianping Guo, Wenchao Han, and Dandan Chen
Atmos. Chem. Phys., 21, 6199–6220, https://doi.org/10.5194/acp-21-6199-2021, https://doi.org/10.5194/acp-21-6199-2021, 2021
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A convective cloud identification process is developed using geostationary satellite data from Himawari-8.
Convective cloud fraction is generally larger before noon and smaller in the afternoon under polluted conditions, but megacities and complex topography can influence the pattern.
A robust relationship between convective cloud and aerosol loading is found. This pattern varies with terrain height and is modulated by varying thermodynamic, dynamical, and humidity conditions during the day.
Ulrike Proske, Verena Bessenbacher, Zane Dedekind, Ulrike Lohmann, and David Neubauer
Atmos. Chem. Phys., 21, 5195–5216, https://doi.org/10.5194/acp-21-5195-2021, https://doi.org/10.5194/acp-21-5195-2021, 2021
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Ice crystals falling out of one cloud can initiate freezing in a second cloud below. We estimate the occurrence frequency of this natural cloud seeding over Switzerland from satellite data and sublimation calculations. We find that such situations with an ice cloud above another cloud are frequent and that the falling crystals survive the fall between two clouds in a significant number of cases, suggesting that natural cloud seeding is an important phenomenon over Switzerland.
Joseph Sedlar, Adele Igel, and Hagen Telg
Atmos. Chem. Phys., 21, 4149–4167, https://doi.org/10.5194/acp-21-4149-2021, https://doi.org/10.5194/acp-21-4149-2021, 2021
Julia Maillard, François Ravetta, Jean-Christophe Raut, Vincent Mariage, and Jacques Pelon
Atmos. Chem. Phys., 21, 4079–4101, https://doi.org/10.5194/acp-21-4079-2021, https://doi.org/10.5194/acp-21-4079-2021, 2021
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Clouds remain a major source of uncertainty in understanding the Arctic climate, due in part to the lack of measurements over the sea ice. In this paper, we exploit a series of lidar profiles acquired from autonomous drifting buoys deployed in the Arctic Ocean and derive a statistic of low cloud frequency and macrophysical properties. We also show that clouds contribute to warm the surface in the shoulder seasons but not significantly from May to September.
Kevin M. Smalley and Anita D. Rapp
Atmos. Chem. Phys., 21, 2765–2779, https://doi.org/10.5194/acp-21-2765-2021, https://doi.org/10.5194/acp-21-2765-2021, 2021
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We use satellite observations of shallow cumulus clouds to investigate the influence of cloud size on the ratio of cloud water path to rainwater (WRR) in different environments. For a fixed temperature and relative humidity, WRR increases with cloud size, but it varies little with aerosols. These results imply that increasing WRR with rising temperature relates not only to deeper clouds but also to more frequent larger clouds.
Iris-Amata Dion, Cyrille Dallet, Philippe Ricaud, Fabien Carminati, Thibaut Dauhut, and Peter Haynes
Atmos. Chem. Phys., 21, 2191–2210, https://doi.org/10.5194/acp-21-2191-2021, https://doi.org/10.5194/acp-21-2191-2021, 2021
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Ice in the tropopause has a strong radiative effect on climate. The amount of ice injected (∆IWC) up to the tropical tropopause layer has been shown to be the highest over the Maritime Continent (MC), a region that includes Indonesia. ∆IWC is studied over islands and sea of the MC. Space-borne observations of ice, precipitation and lightning are used to estimate ∆IWC and are compared to ∆IWC estimated from the ERA5 reanalyses. It is shown that Java is the area of the greatest ∆IWC over the MC.
Claudia J. Stubenrauch, Giacomo Caria, Sofia E. Protopapadaki, and Friederike Hemmer
Atmos. Chem. Phys., 21, 1015–1034, https://doi.org/10.5194/acp-21-1015-2021, https://doi.org/10.5194/acp-21-1015-2021, 2021
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Tropical anvils formed by convective outflow play a crucial role in modulating the Earth’s energy budget and heat transport. To explore the relation between these anvils and convection, we built 3D radiative heating fields, based on machine learning employed on cloud and atmospheric properties from IR sounder and meteorological reanalyses, trained on lidar–radar retrievals. The 15-year time series reveals colder convective systems during warm periods, affecting the atmospheric heating structure.
Gregor Pante, Peter Knippertz, Andreas H. Fink, and Anke Kniffka
Atmos. Chem. Phys., 21, 35–55, https://doi.org/10.5194/acp-21-35-2021, https://doi.org/10.5194/acp-21-35-2021, 2021
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Seasonal rainfall amounts along the densely populated West African Guinea coast have been decreasing during the past 35 years, with recently accelerating trends. We find strong indications that this is in part related to increasing human air pollution in the region. Given the fast increase in emissions, the political implications of this work are significant. Reducing air pollution locally and regionally would mitigate an imminent health crisis and socio-economic damage from reduced rainfall.
Cristofer Jimenez, Albert Ansmann, Ronny Engelmann, David Donovan, Aleksey Malinka, Jörg Schmidt, Patric Seifert, and Ulla Wandinger
Atmos. Chem. Phys., 20, 15247–15263, https://doi.org/10.5194/acp-20-15247-2020, https://doi.org/10.5194/acp-20-15247-2020, 2020
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A novel lidar method to study cloud microphysical properties (of liquid water clouds) and to study aerosol–cloud interaction (ACI) is developed and presented in this paper. In Part 1, the theoretical framework including an error analysis is given together with an overview of the aerosol information that the same lidar system can obtain. The ACI concept based on aerosol and cloud information is also explained. Applications of the proposed approach to lidar measurements are presented in Part 2.
Cristofer Jimenez, Albert Ansmann, Ronny Engelmann, David Donovan, Aleksey Malinka, Patric Seifert, Robert Wiesen, Martin Radenz, Zhenping Yin, Johannes Bühl, Jörg Schmidt, Boris Barja, and Ulla Wandinger
Atmos. Chem. Phys., 20, 15265–15284, https://doi.org/10.5194/acp-20-15265-2020, https://doi.org/10.5194/acp-20-15265-2020, 2020
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Part 2 presents the application of the dual-FOV polarization lidar technique introduced in Part 1. A lidar system was upgraded with a second polarization telescope, and it was deployed at the southernmost tip of South America. A comparison with alternative remote sensing techniques and the evaluation of the aerosol–cloud–wind relation in a convective boundary layer in pristine marine conditions are presented in two case studies, demonstrating the potential of the approach for ACI studies.
Johannes Quaas, Antti Arola, Brian Cairns, Matthew Christensen, Hartwig Deneke, Annica M. L. Ekman, Graham Feingold, Ann Fridlind, Edward Gryspeerdt, Otto Hasekamp, Zhanqing Li, Antti Lipponen, Po-Lun Ma, Johannes Mülmenstädt, Athanasios Nenes, Joyce E. Penner, Daniel Rosenfeld, Roland Schrödner, Kenneth Sinclair, Odran Sourdeval, Philip Stier, Matthias Tesche, Bastiaan van Diedenhoven, and Manfred Wendisch
Atmos. Chem. Phys., 20, 15079–15099, https://doi.org/10.5194/acp-20-15079-2020, https://doi.org/10.5194/acp-20-15079-2020, 2020
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Anthropogenic pollution particles – aerosols – serve as cloud condensation nuclei and thus increase cloud droplet concentration and the clouds' reflection of sunlight (a cooling effect on climate). This Twomey effect is poorly constrained by models and requires satellite data for better quantification. The review summarizes the challenges in properly doing so and outlines avenues for progress towards a better use of aerosol retrievals and better retrievals of droplet concentrations.
Hwayoung Jeoung, Guosheng Liu, Kwonil Kim, Gyuwon Lee, and Eun-Kyoung Seo
Atmos. Chem. Phys., 20, 14491–14507, https://doi.org/10.5194/acp-20-14491-2020, https://doi.org/10.5194/acp-20-14491-2020, 2020
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Radar and radiometer observations were used to study cloud liquid and snowfall in three types of snow clouds. While near-surface and shallow clouds have an area fraction of 90 %, deep clouds contribute half of the total snowfall volume. Deeper clouds have heavier snowfall, although cloud liquid is equally abundant in all three cloud types. The skills of a GMI Bayesian algorithm are examined. Snowfall in deep clouds may be reasonably retrieved, but it is challenging for near-surface clouds.
Juan Huo, Yufang Tian, Xue Wu, Congzheng Han, Bo Liu, Yongheng Bi, Shu Duan, and Daren Lyu
Atmos. Chem. Phys., 20, 14377–14392, https://doi.org/10.5194/acp-20-14377-2020, https://doi.org/10.5194/acp-20-14377-2020, 2020
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A detailed analysis of ice cloud physical properties is presented based on 4 years of surface Ka-band radar measurements in Beijing, where the summer oceanic monsoon from the ocean and winter continental monsoon prevail alternately. More than 6000 ice cloud clusters were studied to investigate their physical properties, such as height, horizontal extent, temperature dependence and origination type, which can serve as a reference for parameterization and characterization in global climate models.
Jie Gong, Xiping Zeng, Dong L. Wu, S. Joseph Munchak, Xiaowen Li, Stefan Kneifel, Davide Ori, Liang Liao, and Donifan Barahona
Atmos. Chem. Phys., 20, 12633–12653, https://doi.org/10.5194/acp-20-12633-2020, https://doi.org/10.5194/acp-20-12633-2020, 2020
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This work provides a novel way of using polarized passive microwave measurements to study the interlinked cloud–convection–precipitation processes. The magnitude of differences between polarized radiances is found linked to ice microphysics (shape, size, orientation and density), mesoscale dynamic and thermodynamic structures, and surface precipitation. We conclude that passive sensors with multiple polarized channel pairs may serve as cheaper and useful substitutes for spaceborne radar sensors.
Feng Zhang, Qiu-Run Yu, Jia-Li Mao, Chen Dan, Yanyu Wang, Qianshan He, Tiantao Cheng, Chunhong Chen, Dongwei Liu, and Yanping Gao
Atmos. Chem. Phys., 20, 11799–11808, https://doi.org/10.5194/acp-20-11799-2020, https://doi.org/10.5194/acp-20-11799-2020, 2020
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In this work, we make the three main contributions. (1) We reveal the remarkable differences in the geographical distributions of cirrus over the Tibetan Plateau regarding the cloud top height. (2) The orography, gravity wave, and deep convection determine the formation of cirrus with a cloud top below 9, at 9–12, and above 12 km, respectively. (3) It is the first time the contributions of the Tibetan Plateau to the presence of cirrus on a regional scale are discussed.
Francesco Cairo, Mauro De Muro, Marcel Snels, Luca Di Liberto, Silvia Bucci, Bernard Legras, Ajil Kottayil, Andrea Scoccione, and Stefano Ghisu
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-1057, https://doi.org/10.5194/acp-2020-1057, 2020
Revised manuscript accepted for ACP
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A lidar was in Palau Island in February–March 2016. Clouds were observed, peaking at 3 km below the high Cold Point Tropopause (CPT). Their occurrence was linked with cold anomalies, while in warm cases, cirrus were restricted to 5 km below the CPT. Thin subvisible cirrus near the CPT had distinctive characteristics. They were linked to wave induced cold anomalies. Back trajectories are mostly compatible with convective outflow, while some distinctive SVC may be originated in situ.
Adeyemi A. Adebiyi, Paquita Zuidema, Ian Chang, Sharon P. Burton, and Brian Cairns
Atmos. Chem. Phys., 20, 11025–11043, https://doi.org/10.5194/acp-20-11025-2020, https://doi.org/10.5194/acp-20-11025-2020, 2020
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Over the southeast Atlantic, interactions between the low-level clouds and the overlying smoke aerosols have previously been highlighted, but no study has yet focused on the presence of the mid-level clouds that complicate the aerosol–cloud interactions. Here we show that these optically thin super-cooled mid-level clouds are relatively common, and they frequently occur at the top of the smoke layer between August and October with significant radiative impacts on the low-level clouds.
Haoran Li, Jussi Tiira, Annakaisa von Lerber, and Dmitri Moisseev
Atmos. Chem. Phys., 20, 9547–9562, https://doi.org/10.5194/acp-20-9547-2020, https://doi.org/10.5194/acp-20-9547-2020, 2020
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A method for classifying rimed and unrimed snow based on X- and Ka-band Doppler radar measurements is developed and applied to synergetic radar observations collected during BAECC 2014. The results show that the radar-observed melting layer properties are highly related to the precipitation intensity. The previously reported bright band sagging is mainly connected to the increase in precipitation intensity, while riming plays a secondary role.
Yulan Hong and Larry Di Girolamo
Atmos. Chem. Phys., 20, 8267–8291, https://doi.org/10.5194/acp-20-8267-2020, https://doi.org/10.5194/acp-20-8267-2020, 2020
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Cloud phase plays a crucial role in Earth radiation budget but is not well understood. Using A-Train satellite observations, this study provides climatological studies of cloud phase characteristics over Southeast Asia on multiple meteorological scales. Results show that ice, liquid, and ice over liquid clouds display distinct spatial heterogeneity and spectral radiance features. The intraseasonal and interannual behaviors of cloud phases are useful to track the MJO and ENSO.
Scott E. Giangrande, Dié Wang, and David B. Mechem
Atmos. Chem. Phys., 20, 7489–7507, https://doi.org/10.5194/acp-20-7489-2020, https://doi.org/10.5194/acp-20-7489-2020, 2020
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The Amazon basin experiences prolific and diverse cloud conditions that are strongly influenced by (and influence via feedbacks) seasonal shifts in the local conditions and larger-scale atmospheric circulations. The primary atmospheric regimes observed during a heavily instrumented 2-year Amazon deployment are classified. We assess the potential atmospheric controls on convective clouds, precipitation, and the propensity for these regimes to promote extremes in precipitation.
Josué Gehring, Annika Oertel, Étienne Vignon, Nicolas Jullien, Nikola Besic, and Alexis Berne
Atmos. Chem. Phys., 20, 7373–7392, https://doi.org/10.5194/acp-20-7373-2020, https://doi.org/10.5194/acp-20-7373-2020, 2020
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In this study, we analyse how large-scale meteorological conditions influenced the local enhancement of snowfall during an intense precipitation event in Korea. We used atmospheric models, weather radars and snowflake images. We found out that a rising airstream in the warm sector of the low pressure system associated to this event influenced the evolution of snowfall. This study highlights the importance of interactions between large and local scales in this intense precipitation event.
Timothy W. Juliano and Zachary J. Lebo
Atmos. Chem. Phys., 20, 7125–7138, https://doi.org/10.5194/acp-20-7125-2020, https://doi.org/10.5194/acp-20-7125-2020, 2020
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In this study, we use a machine learning method to examine the relationship between synoptic-scale changes in the North Pacific High structure and maritime cloud properties. Our novel approach suggests that there is a wide range (>30 W m−2, ~20 % of magnitude) of possible shortwave cloud radiative effect that is a clear function of the circulation pattern. We hope that this work will help improve fundamental understanding of the sensitivity of the climate system to various warm-cloud regimes.
Alyson Douglas and Tristan L'Ecuyer
Atmos. Chem. Phys., 20, 6225–6241, https://doi.org/10.5194/acp-20-6225-2020, https://doi.org/10.5194/acp-20-6225-2020, 2020
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Aerosols, or small, suspended droplets in the atmosphere, are released from anthropogenic activity and interact with warm clouds, leading to changes in the clouds' brightness and size. Our study evaluates how aerosols alter warm clouds and their ability to cool the Earth's surface. We find aerosols make clouds brighter and grow larger in the atmosphere; however, the cooling effect due to whiter, brighter clouds is 5 times the cooling due to an increased extent.
Elena Ruiz-Donoso, André Ehrlich, Michael Schäfer, Evelyn Jäkel, Vera Schemann, Susanne Crewell, Mario Mech, Birte Solveig Kulla, Leif-Leonard Kliesch, Roland Neuber, and Manfred Wendisch
Atmos. Chem. Phys., 20, 5487–5511, https://doi.org/10.5194/acp-20-5487-2020, https://doi.org/10.5194/acp-20-5487-2020, 2020
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Mixed-phase clouds, formed of water droplets and ice crystals, appear frequently in Arctic regions. Characterizing the distribution of liquid water and ice inside the cloud appropriately is important because it influences the cloud's impact on the surface temperature. In this study, we combined images of the cloud top with measurements inside the cloud to analyze in detail the 3D spatial distribution of liquid and ice in two mixed-phase clouds occurring under different meteorological scenarios.
Tatiana Nomokonova, Kerstin Ebell, Ulrich Löhnert, Marion Maturilli, and Christoph Ritter
Atmos. Chem. Phys., 20, 5157–5173, https://doi.org/10.5194/acp-20-5157-2020, https://doi.org/10.5194/acp-20-5157-2020, 2020
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This paper presents an influence of water vapor anomalies on cloud properties and their radiative effect at Ny-Ålesund. The study is based on a 2.5-year active and passive cloud observation and a radiative transfer model. The results show that moist and dry conditions are related to strong changes in cloud occurrence, phase partitioning, water path, and, consequently, modulate the surface radiative budget.
Kalliopi Artemis Voudouri, Elina Giannakaki, Mika Komppula, and Dimitris Balis
Atmos. Chem. Phys., 20, 4427–4444, https://doi.org/10.5194/acp-20-4427-2020, https://doi.org/10.5194/acp-20-4427-2020, 2020
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In this paper we present the variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes. The kind of information presented here can be rather useful in the cirrus parameterisations required as input to radiative transfer models and can be a complementary tool for satellite products that cannot provide cloud vertical structure.
Anna Possner, Ryan Eastman, Frida Bender, and Franziska Glassmeier
Atmos. Chem. Phys., 20, 3609–3621, https://doi.org/10.5194/acp-20-3609-2020, https://doi.org/10.5194/acp-20-3609-2020, 2020
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Cloud water content and the number of droplets inside clouds covary with boundary layer depth. This covariation may amplify the change in water content due to a change in droplet number inferred from long-term observations. Taking this into account shows that the change in water content for increased droplet number in observations and high-resolution simulations agrees in shallow boundary layers. Meanwhile, deep boundary layers are under-sampled in process-scale simulations and observations.
Xiaojian Zheng, Baike Xi, Xiquan Dong, Timothy Logan, Yuan Wang, and Peng Wu
Atmos. Chem. Phys., 20, 3483–3501, https://doi.org/10.5194/acp-20-3483-2020, https://doi.org/10.5194/acp-20-3483-2020, 2020
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The continental low-level stratiform cloud susceptibilities to aerosols were investigated under different absorptive aerosol regimes. The weakly absorbing aerosols, which are more hygroscopic, can better activate as cloud condensation nuclei. The favorable thermodynamic condition enhances the cloud susceptibility, while the cloud-layer heating effect induced by strongly absorbing aerosols dampens the cloud susceptibility. Overall, the clouds are more susceptible to the weakly absorbing aerosols.
Rosa Gierens, Stefan Kneifel, Matthew D. Shupe, Kerstin Ebell, Marion Maturilli, and Ulrich Löhnert
Atmos. Chem. Phys., 20, 3459–3481, https://doi.org/10.5194/acp-20-3459-2020, https://doi.org/10.5194/acp-20-3459-2020, 2020
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Multiyear statistics of persistent low-level mixed-phase clouds observed at an Arctic fjord environment in Svalbard are presented. The effects the local boundary layer (i.e. the fjords' wind climate and surface coupling), regional wind direction, and seasonality have on the cloud occurrence and properties are evaluated using a synergy of ground-based remote sensing methods and auxiliary data. The phenomena considered were found to modify the amount of liquid and ice in the studied clouds.
Hendrik Andersen, Jan Cermak, Julia Fuchs, Peter Knippertz, Marco Gaetani, Julian Quinting, Sebastian Sippel, and Roland Vogt
Atmos. Chem. Phys., 20, 3415–3438, https://doi.org/10.5194/acp-20-3415-2020, https://doi.org/10.5194/acp-20-3415-2020, 2020
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Fog and low clouds (FLCs) are an essential but poorly understood element of Namib regional climate. Here, a satellite-based data set of FLCs in central Namib, reanalysis data, and back trajectories are used to systematically analyze conditions when FLCs occur. Synoptic-scale mechanisms are identified that influence the formation of FLCs and the onshore advection of marine boundary-layer air masses. The findings lead to a new conceptual model of mechanisms that drive FLC variability in the Namib.
Claudia Unglaub, Karoline Block, Johannes Mülmenstädt, Odran Sourdeval, and Johannes Quaas
Atmos. Chem. Phys., 20, 2407–2418, https://doi.org/10.5194/acp-20-2407-2020, https://doi.org/10.5194/acp-20-2407-2020, 2020
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In cloud research, it is necessary to classify clouds. The World Meteorological Organization proposes distinguishing stratiform and cumuliform clouds in three altitude layers. The paper explains why previous approaches to classify clouds fail for many applications and proposes a new classification on the basis of new approaches for satellite retrievals to derive cloud-base height, in combination with cloud inhomogeneity. It is demonstrated that this discriminates cloud characteristics well.
Diego Villanueva, Bernd Heinold, Patric Seifert, Hartwig Deneke, Martin Radenz, and Ina Tegen
Atmos. Chem. Phys., 20, 2177–2199, https://doi.org/10.5194/acp-20-2177-2020, https://doi.org/10.5194/acp-20-2177-2020, 2020
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Spaceborne retrievals of cloud phase were analysed together with an atmospheric composition model to assess the global frequency of ice and liquid clouds. This analysis showed that at equal temperature the average occurrence of ice clouds increases for higher dust mixing ratios on a day-to-day basis in the middle and high latitudes. This indicates that mineral dust may have a strong impact on the occurrence of ice clouds even in remote areas.
Yilun Chen, Guangcan Chen, Chunguang Cui, Aoqi Zhang, Rong Wan, Shengnan Zhou, Dongyong Wang, and Yunfei Fu
Atmos. Chem. Phys., 20, 1131–1145, https://doi.org/10.5194/acp-20-1131-2020, https://doi.org/10.5194/acp-20-1131-2020, 2020
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The vertical evolution of the cloud effective radius reflects the precipitation-forming process. We developed an algorithm for retrieving it based on objective cloud-cluster identification rather than the subjective polygon of the conventional method. The profile shows completely different morphologies in different life stages of the cloud cluster, which is important in the characterization of the formation of precipitation and the temporal evolution of microphysical processes.
Amir Erfanian and Rong Fu
Atmos. Chem. Phys., 19, 15199–15216, https://doi.org/10.5194/acp-19-15199-2019, https://doi.org/10.5194/acp-19-15199-2019, 2019
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An eastward advection of dry and warm air in spring was identified as a major drought onset mechanism over the US Great Plains (GP). Further breakdown of the zonal advection into the dynamic versus thermodynamic contributions revealed dominance of the latter in the tropospheric drying observed during the onset of GP 2011 and 2012 droughts. The dependence of thermodynamic advection on moisture gradient links the spring precipitation in the Rockies and US southwest to the GP summer precipitation.
Artem G. Feofilov and Claudia J. Stubenrauch
Atmos. Chem. Phys., 19, 13957–13972, https://doi.org/10.5194/acp-19-13957-2019, https://doi.org/10.5194/acp-19-13957-2019, 2019
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Clouds play an important role in the energy budget of the planet: optically thick clouds reflect the incoming solar radiation leading to cooling of the Earth, while thinner clouds act as
greenhouse filmspreventing escape of the Earth’s infrared radiation to space. Satellite observations provide a continuous survey of clouds over the whole globe. In this work, we use a combination of two space-borne sounders to retrieve and analyse the characteristics of diurnal variation of high-level clouds.
Nils Madenach, Cintia Carbajal Henken, René Preusker, Odran Sourdeval, and Jürgen Fischer
Atmos. Chem. Phys., 19, 13535–13546, https://doi.org/10.5194/acp-19-13535-2019, https://doi.org/10.5194/acp-19-13535-2019, 2019
Kadiri Saikranthi, Basivi Radhakrishna, Thota Narayana Rao, and Sreedharan Krishnakumari Satheesh
Atmos. Chem. Phys., 19, 10423–10432, https://doi.org/10.5194/acp-19-10423-2019, https://doi.org/10.5194/acp-19-10423-2019, 2019
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Recent studies have shown that simulation of monsoons can be improved with an exact representation of SST–precipitation relationship. The vertical structure of precipitation with SST is distinctly different over the Arabian Sea than over the Bay of Bengal. The reflectivity profiles show variation with SST over the Arabian Sea and do not show considerable variation with SST over the Bay of Bengal. The variations in reflectivity profiles seem to originate at the cloud formation stage itself.
Ralf Bennartz, Frank Fell, Claire Pettersen, Matthew D. Shupe, and Dirk Schuettemeyer
Atmos. Chem. Phys., 19, 8101–8121, https://doi.org/10.5194/acp-19-8101-2019, https://doi.org/10.5194/acp-19-8101-2019, 2019
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The Greenland Ice Sheet (GrIS) is rapidly melting. Snowfall is the only source of ice mass over the GrIS. We use satellite observations to assess how much snow on average falls over the GrIS and what the annual cycle and spatial distribution of snowfall is. We find the annual mean snowfall over the GrIS inferred from CloudSat to be 34 ± 7.5 cm yr−1 liquid equivalent.
Andrew Geiss and Roger Marchand
Atmos. Chem. Phys., 19, 7547–7565, https://doi.org/10.5194/acp-19-7547-2019, https://doi.org/10.5194/acp-19-7547-2019, 2019
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The 13-year trends in cloud occurrence, observed by NASA's Multi-angle Imaging SpectroRadiometer, over the world's extratropical ocean basins are compared to trends in meteorological variables. We identify several patterns of changing cloud occurrence that correspond to specific patterns in trending meteorology. We find that many of these trends are related to changes in major modes of climate variability.
Constantino Listowski, Julien Delanoë, Amélie Kirchgaessner, Tom Lachlan-Cope, and John King
Atmos. Chem. Phys., 19, 6771–6808, https://doi.org/10.5194/acp-19-6771-2019, https://doi.org/10.5194/acp-19-6771-2019, 2019
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Using satellite cloud products we investigate the supercooled liquid-water (SLW) distribution Antarctic-wide for the first time. We demonstrate differences between the monthly evolution of the marine low-level mixed-phase clouds and that of the marine low-level pure SLW clouds. In addition to the temperature and sea ice fraction as factors explaining the low-level liquid-cloud seasonal cycle, ice nuclei emissions from open water may also be driving the mixed-phase cloud monthly evolution.
Iris-Amata Dion, Philippe Ricaud, Peter Haynes, Fabien Carminati, and Thibaut Dauhut
Atmos. Chem. Phys., 19, 6459–6479, https://doi.org/10.5194/acp-19-6459-2019, https://doi.org/10.5194/acp-19-6459-2019, 2019
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Water vapour and ice cirrus clouds near the tropical tropopause layer (TTL) have a strong radiative impact on climate. Based on space-borne observations, we have developed a model linking ice in the upper troposphere from the Microwave Limb Sounder (MLS) to precipitation in the troposphere from the Tropical Rainfall Measurement Mission (TRMM). Our study quantifies the amount of ice injected into the TTL by deep convection over tropical lands and oceans by investigating the diurnal cycle of ice.
Alyson Douglas and Tristan L'Ecuyer
Atmos. Chem. Phys., 19, 6251–6268, https://doi.org/10.5194/acp-19-6251-2019, https://doi.org/10.5194/acp-19-6251-2019, 2019
Short summary
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Aerosols are released by natural and human activities. When aerosols encounter clouds they interact in what is known as the indirect effect. Brighter clouds are expected due to the microphysical response; however, certain environments can trigger a modified response. Limits on the stability, humidity, and cloud thickness are applied regionally to investigate local cloud responses to aerosol, resulting in a range of indirect effects that would result in significant cooling or slight warming.
Andrew I. Barrett, Christopher D. Westbrook, John C. Nicol, and Thorwald H. M. Stein
Atmos. Chem. Phys., 19, 5753–5769, https://doi.org/10.5194/acp-19-5753-2019, https://doi.org/10.5194/acp-19-5753-2019, 2019
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We use radars at three wavelengths to study cloud properties. The full Doppler spectra (rather than calculated averages of the spectra) are compared for the radars. This allows us to estimate the size and number of ice particles within the cloud. By following the evolution of the ice particles, we observe a region where particles rapidly and consistently increase in size. The observations suggest that these large particles form through interlocking of branched arms of smaller ice particles.
David P. Duda, Sarah T. Bedka, Patrick Minnis, Douglas Spangenberg, Konstantin Khlopenkov, Thad Chee, and William L. Smith Jr.
Atmos. Chem. Phys., 19, 5313–5330, https://doi.org/10.5194/acp-19-5313-2019, https://doi.org/10.5194/acp-19-5313-2019, 2019
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We use one year (2012) of satellite imagery obtained from two NASA research satellites, Terra and Aqua, to detect linear contrail coverage and to estimate their physical properties over the Northern Hemisphere. The satellite-derived properties are compared with results collected from the same sensors in 2006 to estimate whether the impact of contrail coverage on climate has changed. The study is the first of its kind to measure contrail properties over a near-global scale from satellite imagery.
Emily M. McCullough, James R. Drummond, and Thomas J. Duck
Atmos. Chem. Phys., 19, 4595–4614, https://doi.org/10.5194/acp-19-4595-2019, https://doi.org/10.5194/acp-19-4595-2019, 2019
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Very thin (<10 m) laminations within Arctic clouds have been observed in all seasons using the Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh–Mie–Raman lidar (CRL) at the Polar Environment Atmospheric Research Laboratory (PEARL; Eureka, Nunavut, Canadian High Arctic). The laminations can last longer than 24 h and are often associated with precipitation and atmospheric stability. This has implications for our understanding of cloud internal structure and processes.
Hendrik Andersen, Jan Cermak, Irina Solodovnik, Luca Lelli, and Roland Vogt
Atmos. Chem. Phys., 19, 4383–4392, https://doi.org/10.5194/acp-19-4383-2019, https://doi.org/10.5194/acp-19-4383-2019, 2019
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Fog and low clouds (FLCs) are an essential but poorly understood component of Namib-region climate. This study uses observations from multiple satellite platforms and ground-based measurements to coherently characterize Namib-region FLC patterns. Findings concerning the seasonal cycle of the vertical structure and the diurnal cycle of FLCs lead to a new conceptual model of the spatiotemporal dynamics of FLCs in the Namib and help to improve the understanding of underlying processes.
Tatiana Nomokonova, Kerstin Ebell, Ulrich Löhnert, Marion Maturilli, Christoph Ritter, and Ewan O'Connor
Atmos. Chem. Phys., 19, 4105–4126, https://doi.org/10.5194/acp-19-4105-2019, https://doi.org/10.5194/acp-19-4105-2019, 2019
Short summary
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In this study, properties of clouds at the French–German Arctic research station in Ny-Ålesund are related to in-cloud thermodynamic conditions. The dataset used was collected within the Arctic Amplification project with a set of active and passive remote instruments. The results are compared with a model output. Significant divergence in observations and modelling of single-layer ice and mixed-phase clouds was found.
Grégory Cesana, Anthony D. Del Genio, Andrew S. Ackerman, Maxwell Kelley, Gregory Elsaesser, Ann M. Fridlind, Ye Cheng, and Mao-Sung Yao
Atmos. Chem. Phys., 19, 2813–2832, https://doi.org/10.5194/acp-19-2813-2019, https://doi.org/10.5194/acp-19-2813-2019, 2019
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The response of low clouds to climate change (i.e., cloud feedbacks) is still pointed out as being the largest source of uncertainty in climate models. Here we use CALIPSO observations to discriminate climate models that reproduce observed interannual change of cloud fraction with SST forcings, referred to as a present-day cloud feedback. Modeling moist processes in the planetary boundary layer is crucial to produce large stratocumulus decks and realistic present-day cloud feedbacks.
Minttu Tuononen, Ewan J. O'Connor, and Victoria A. Sinclair
Atmos. Chem. Phys., 19, 1985–2000, https://doi.org/10.5194/acp-19-1985-2019, https://doi.org/10.5194/acp-19-1985-2019, 2019
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Many applications require accurate forecasts of the amount of solar radiation reaching the surface, such as solar energy and UV radiation forecasts. This also means that cloud must be correctly forecast. We investigated the skill of these forecasts over Helsinki, Finland, using cloud and solar radiation observations. We found that there were errors in the model radiation forecast even when the clouds were correctly forecast, which we attribute to incorrect representation of the cloud properties.
Cited articles
Ackerman, A. S., Toon, O. B., Taylor, J. P., Johnson, D. W., Hobbs, P. V.,
and Ferek, R. J.: Effects of Aerosols on Cloud Albedo: Evaluation of Twomey's
Parameterization of Cloud Susceptibility Using Measurements of Ship Tracks,
J. Atmos. Sci., 57, 2684–2695,
https://doi.org/10.1175/1520-0469(2000)057<2684:EOAOCA>2.0.CO;2, 2000. a
Albrecht, B. A.: Aerosols, Cloud Microphysics, and Fractional Cloudiness,
Science, 245, 1227–1230, https://doi.org/10.1126/science.245.4923.1227, 1989. a, b
Anderberg, M.: Cluster analysis for applications, Elsevier, New York, 1973. a
Andersen, H., Cermak, J., Fuchs, J., Knutti, R., and Lohmann, U.:
Understanding the drivers of marine liquid-water cloud occurrence and
properties with global observations using neural networks, Atmos. Chem.
Phys., 17, 9535–9546, https://doi.org/10.5194/acp-17-9535-2017, 2017. a
Baker, M. B., Corbin, R. G., and Latham, J.: The influence of entrainment on
the evolution of cloud droplet spectra: I. A model of inhomogeneous mixing,
Q. J. Roy. Meteor. Soc., 106, 581–598, https://doi.org/10.1002/qj.49710644914, 1980. a
Bellouin, N. and Quaas, J.: Bounding the effective aerosol radiative forcing,
Rev. Geophys., in preparation, 2019. a
Bellouin, N., Mann, G. W., Woodhouse, M. T., Johnson, C., Carslaw, K. S., and
Dalvi, M.: Impact of the modal aerosol scheme GLOMAP-mode on aerosol forcing
in the Hadley Centre Global Environmental Model, Atmos. Chem. Phys., 13,
3027–3044, https://doi.org/10.5194/acp-13-3027-2013, 2013. a, b
Bender, F. A.-M., Frey, L., McCoy, D. T., Grosvenor, D. P., and Mohrmann,
J. K.: Assessment of aerosol–cloud–radiation correlations in satellite
observations, climate models and reanalysis, Clim. Dynam., 1–22,
https://doi.org/10.1007/s00382-018-4384-z, 2018. a
Bennartz, R. and Rausch, J.: Global and regional estimates of warm cloud
droplet number concentration based on 13 years of AQUA-MODIS observations,
Atmos. Chem. Phys., 17, 9815–9836, https://doi.org/10.5194/acp-17-9815-2017,
2017. a
Boucher, O., Randall, D. A., Artaxo, P., Bretherton, C., Feingold, G.,
Forster, P. M., Kerminen, V.-M., Kondo, Y., Liao, H., Lohmann, U., Rasch, P.,
Satheesh, S. K., Sherwood, S., Stevens, B., and Zhang, X. Y.: Clouds and
Aerosols, in: Climate Change 2013 – The Physical Science Basis: Working
Group I Contribution to the Fifth Assessment Report of the Intergovernmental
Panel on Climate Change, Cambridge University Press, 571–658,
https://doi.org/10.1017/CBO9781107415324.016, 2014. a
Brenguier, J.-L., Pawlowska, H., Schüller, L., Preusker, R., Fischer, J.,
and Fouquart, Y.: Radiative Properties of Boundary Layer Clouds: Droplet
Effective Radius versus Number Concentration, J. Atmos. Sci., 57, 803–821,
https://doi.org/10.1175/1520-0469(2000)057<0803:RPOBLC>2.0.CO;2, 2000. a
Breon, F.-M. and Doutriaux-Boucher, M.: A comparison of cloud droplet radii
measured from space, IEEE T. Geosci. Remote, 43, 1796–1805,
https://doi.org/10.1109/TGRS.2005.852838, 2005. a
Burnet, F. and Brenguier, J.-L.: Observational Study of the
Entrainment-Mixing Process in Warm Convective Clouds, J. Atmos. Sci., 64,
1995–2011, https://doi.org/10.1175/JAS3928.1, 2007. a
Chand, D., Wood, R., Ghan, S. J., Wang, M., Ovchinnikov, M., Rasch, P. J.,
Miller, S., Schichtel, B., and Moore, T.: Aerosol optical depth increase in
partly cloudy conditions, J. Geophys. Res., 117, 17207,
https://doi.org/10.1029/2012JD017894, 2012. a
Chen, Y.-C., Christensen, M. W., Xue, L., Sorooshian, A., Stephens, G. L.,
Rasmussen, R. M., and Seinfeld, J. H.: Occurrence of lower cloud albedo in
ship tracks, Atmos. Chem. Phys., 12, 8223–8235,
https://doi.org/10.5194/acp-12-8223-2012, 2012. a
Chi, J. T., Chi, E. C., and Baraniuk, R. G.: k-POD: A Method for k-Means
Clustering of Missing Data, Am. Stat., 70, 91–99,
https://doi.org/10.1080/00031305.2015.1086685, 2016. a
Christensen, M. W. and Stephens, G. L.: Microphysical and macrophysical
responses of marine stratocumulus polluted by underlying ships: Evidence of
cloud deepening, J. Geophys. Res., 116, D03201, https://doi.org/10.1029/2010JD014638,
2011. a
Christensen, M. W., Suzuki, K., Zambri, B., and Stephens, G. L.: Ship track
observations of a reduced shortwave aerosol indirect effect in mixed-phase
clouds, Geophys. Res. Lett., 41, 6970–6977, https://doi.org/10.1002/2014GL061320,
2014. a, b, c, d
Christensen, M. W., Chen, Y.-C., and Stephens, G. L.: Aerosol Indirect Effect
Dictated by Liquid Clouds, J. Geophys. Res., 121, 14636–14650,
https://doi.org/10.1002/2016JD025245, 2016. a
Christensen, M. W., Neubauer, D., Poulsen, C. A., Thomas, G. E., McGarragh,
G. R., Povey, A. C., Proud, S. R., and Grainger, R. G.: Unveiling
aerosol–cloud interactions – Part 1: Cloud contamination in satellite
products enhances the aerosol indirect forcing estimate, Atmos. Chem. Phys.,
17, 13151–13164, https://doi.org/10.5194/acp-17-13151-2017, 2017. a, b, c, d
Dagan, G., Koren, I., and Altaratz, O.: Competition between core and
periphery-based processes in warm convective clouds – from invigoration to
suppression, Atmos. Chem. Phys., 15, 2749–2760,
https://doi.org/10.5194/acp-15-2749-2015, 2015. a
Dagan, G., Koren, I., Altaratz, O., and Heiblum, R. H.: Time-dependent,
non-monotonic response of warm convective cloud fields to changes in aerosol
loading, Atmos. Chem. Phys., 17, 7435–7444,
https://doi.org/10.5194/acp-17-7435-2017, 2017. a, b
Eastman, R. and Wood, R.: Factors Controlling Low-Cloud Evolution over the
Eastern Subtropical Oceans: A Lagrangian Perspective Using the A-Train
Satellites, J. Atmos. Sci., 73, 331–351, https://doi.org/10.1175/JAS-D-15-0193.1,
2016. a, b
Ebmeier, S. K., Sayer, A. M., Grainger, R. G., Mather, T. A., and Carboni,
E.: Systematic satellite observations of the impact of aerosols from passive
volcanic degassing on local cloud properties, Atmos. Chem. Phys., 14,
10601–10618, https://doi.org/10.5194/acp-14-10601-2014, 2014. a
Engström, A., Bender, F. A.-M., Charlson, R. J., and Wood, R.:
Geographically coherent patterns of albedo enhancement and suppression
associated with aerosol sources and sinks, Tellus B, 67, 26442,
https://doi.org/10.3402/tellusb.v67.26442, 2015. a
Gassó, S.: Satellite observations of the impact of weak volcanic activity
on marine clouds, J. Geophys. Res., 113, D14S19, https://doi.org/10.1029/2007JD009106,
2008. a, b
Gerber, H., Frick, G., Malinowski, S. P., Brenguier, J.-L., and Burnet, F.:
Holes and Entrainment in Stratocumulus, J. Atmos. Sci., 62, 443–459,
https://doi.org/10.1175/JAS-3399.1, 2005. a
Goren, T. and Rosenfeld, D.: Decomposing aerosol cloud radiative effects into
cloud cover, liquid water path and Twomey components in marine stratocumulus,
Atmos. Res., 138, 378–393, https://doi.org/10.1016/j.atmosres.2013.12.008, 2014. a, b, c
Grandey, B. S., Stier, P., and Wagner, T. M.: Investigating relationships
between aerosol optical depth and cloud fraction using satellite, aerosol
reanalysis and general circulation model data, Atmos. Chem. Phys., 13,
3177–3184, https://doi.org/10.5194/acp-13-3177-2013, 2013. a
Grosvenor, D. P. and Wood, R.: The effect of solar zenith angle on MODIS
cloud optical and microphysical retrievals within marine liquid water clouds,
Atmos. Chem. Phys., 14, 7291–7321, https://doi.org/10.5194/acp-14-7291-2014,
2014. a, b, c, d
Grosvenor, D. P., Field, P. R., Hill, A. A., and Shipway, B. J.: The relative
importance of macrophysical and cloud albedo changes for aerosol-induced
radiative effects in closed-cell stratocumulus: insight from the modelling of
a case study, Atmos. Chem. Phys., 17, 5155–5183,
https://doi.org/10.5194/acp-17-5155-2017, 2017. a
Grosvenor, D. P., Sourdeval, O., Zuidema, P., Ackerman, A., Alexandrov,
M. D., Bennartz, R., Boers, R., Cairns, B., Chiu, J. C., Christensen, M.,
Deneke, H., Diamond, M., Feingold, G., Fridlind, A., Hünerbein, A.,
Knist, C., Kollias, P., Marshak, A., McCoy, D., Merk, D., Painemal, D.,
Rausch, J., Rosenfeld, D., Russchenberg, H., Seifert, P., Sinclair, K.,
Stier, P., van Diedenhoven, B., Wendisch, M., Werner, F., Wood, R., Zhang,
Z., and Quaas, J.: Remote Sensing of Droplet Number Concentration in Warm
Clouds: A Review of the Current State of Knowledge and Perspectives, Rev.
Geophys., 56, 409–453, https://doi.org/10.1029/2017RG000593, 2018. a, b
Gryspeerdt, E. and Stier, P.: Regime-based analysis of aerosol-cloud
interactions, Geophys. Res. Lett., 39, L21802, https://doi.org/10.1029/2012GL053221,
2012. a, b, c
Gryspeerdt, E., Stier, P., and Grandey, B. S.: Cloud fraction mediates the
aerosol optical depth-cloud top height relationship, Geophys. Res. Lett., 41,
3622–3627, https://doi.org/10.1002/2014GL059524, 2014a. a
Gryspeerdt, E., Stier, P., and Partridge, D. G.: Satellite observations of
cloud regime development: the role of aerosol processes, Atmos. Chem. Phys.,
14, 1141–1158, https://doi.org/10.5194/acp-14-1141-2014, 2014b. a, b
Gryspeerdt, E., Quaas, J., Ferrachat, S., Gettelman, A., Ghan, S., Lohmann,
U., Morrison, H., Neubauer, D., Partridge, D. G., Stier, P., Takemura, T.,
Wang, H., Wang, M., and Zhang, K.: Constraining the instantaneous aerosol
influence on cloud albedo, P. Natl. Acad. Sci. USA, 114, 4899–4904,
https://doi.org/10.1073/pnas.1617765114, 2017. a, b, c
Han, Q., Rossow, W. B., Zeng, J., and Welch, R.: Three Different Behaviors of
Liquid Water Path of Water Clouds in Aerosol–Cloud Interactions, J. Atmos.
Sci., 59, 726–735, https://doi.org/10.1175/1520-0469(2002)059<0726:TDBOLW>2.0.CO;2,
2002. a
Heyn, I., Block, K., Mülmenstädt, J., Gryspeerdt, E., Kühne, P.,
Salzmann, M., and Quaas, J.: Assessment of simulated aerosol effective
radiative forcings in the terrestrial spectrum, Geophys. Res. Lett., 44,
1001–1007, https://doi.org/10.1002/2016GL071975, 2017. a
Hobbs, P. V., Garrett, T. J., Ferek, R. J., Strader, S. R., Hegg, D. A.,
Frick, G. M., Hoppel, W. A., Gasparovic, R. F., Russell, L. M., Johnson,
D. W., O'Dowd, C., Durkee, P. A., Nielsen, K. E., and Innis, G.: Emissions
from Ships with respect to Their Effects on Clouds, J. Atmos. Sci., 57,
2570–2590, https://doi.org/10.1175/1520-0469(2000)057<2570:EFSWRT>2.0.CO;2, 2000. a
Jiang, H., Xue, H., Teller, A., Feingold, G., and Levin, Z.: Aerosol effects
on the lifetime of shallow cumulus, Geophys. Res. Lett., 33, L14806,
https://doi.org/10.1029/2006GL026024, 2006. a
Kaufman, Y. J., Koren, I., Remer, L. A., Rosenfeld, D., and Rudich, Y.: The
effect of smoke, dust, and pollution aerosol on shallow cloud development
over the Atlantic Ocean, P. Natl. Acad. Sci. USA, 102, 11207–11212,
https://doi.org/10.1073/pnas.0505191102, 2005. a
Kinne, S.: Aerosol radiative effects with MACv2, Atmos. Chem. Phys. Discuss.,
https://doi.org/10.5194/acp-2018-949, in review, 2019. a, b
Koren, I., Kaufman, Y. J., Rosenfeld, D., Remer, L. A., and Rudich, Y.:
Aerosol invigoration and restructuring of Atlantic convective clouds,
Geophys. Res. Lett., 32, L14828, https://doi.org/10.1029/2005GL023187, 2005. a
Koren, I., Dagan, G., and Altaratz, O.: From aerosol-limited to invigoration
of warm convective clouds, Science, 344, 1143–1146,
https://doi.org/10.1126/science.1252595, 2014. a, b
Lebsock, M. and Su, H.: Application of active spaceborne remote sensing for
understanding biases between passive cloud water path retrievals, J. Geophys.
Res., 119, 8962–8979, https://doi.org/10.1002/2014JD021568, 2014. a
Lebsock, M., Stephens, G., and Kummerow, C.: Multisensor satellite
observations of aerosol effects on warm clouds, J. Geophys. Res., 113,
D15205, https://doi.org/10.1029/2008JD009876, 2008. a
Malavelle, F. F., Haywood, J. M., Jones, A., Gettelman, A., Clarisse, L.,
Bauduin, S., Allan, R. P., Karset, I. H. H., Kristjansson, J. E., Oreopoulos,
L., Cho, N., Lee, D., Bellouin, N., Boucher, O., Grosvenor, D. P., Carslaw,
K. S., Dhomse, S., Mann, G. W., Schmidt, A., Coe, H., Hartley, M. E., Dalvi,
M., Hill, A. A., Johnson, B. T., Johnson, C. E., Knight, J. R., O'Connor,
F. M., Partridge, D. G., Stier, P., Myhre, G., Platnick, S., Stephens, G. L.,
Takahashi, H., and Thordarson, T.: Strong constraints on aerosol–cloud
interactions from volcanic eruptions, Nature, 546, 485–491,
https://doi.org/10.1038/nature22974, 2017. a, b, c, d, e
Marchand, R., Ackerman, T., Smyth, M., and Rossow, W. B.: A review of cloud
top height and optical depth histograms from MISR, ISCCP, and MODIS, J.
Geophys. Res., 115, D16206, https://doi.org/10.1029/2009JD013422, 2010. a
Matsui, T., Masunaga, H., Kreidenweis, S. M., Pielke, R. A., Tao, W.-K.,
Chin, M., and Kaufman, Y. J.: Satellite-based assessment of marine low cloud
variability associated with aerosol, atmospheric stability, and the diurnal
cycle, J. Geophys. Res., 111, D17204, https://doi.org/10.1029/2005JD006097, 2006. a
McCoy, D. T., Bender, F. A.-M., Mohrmann, J. K. C., Hartmann, D. L., Wood,
R., and Grosvenor, D. P.: The global aerosol-cloud first indirect effect
estimated using MODIS, MERRA, and AeroCom, J. Geophys. Res., 122,
1779–1796, https://doi.org/10.1002/2016JD026141, 2017. a, b
McCoy, D. T., Field, P. R., Schmidt, A., Grosvenor, D. P., Bender, F. A.-M.,
Shipway, B. J., Hill, A. A., Wilkinson, J. M., and Elsaesser, G. S.: Aerosol
midlatitude cyclone indirect effects in observations and high-resolution
simulations, Atmos. Chem. Phys., 18, 5821–5846,
https://doi.org/10.5194/acp-18-5821-2018, 2018. a
Merk, D., Deneke, H., Pospichal, B., and Seifert, P.: Investigation of the
adiabatic assumption for estimating cloud micro- and macrophysical properties
from satellite and ground observations, Atmos. Chem. Phys., 16, 933–952,
https://doi.org/10.5194/acp-16-933-2016, 2016. a, b
Meskhidze, N., Remer, L. A., Platnick, S., Negrón Juárez, R.,
Lichtenberger, A. M., and Aiyyer, A. R.: Exploring the differences in cloud
properties observed by the Terra and Aqua MODIS Sensors, Atmos. Chem. Phys.,
9, 3461–3475, https://doi.org/10.5194/acp-9-3461-2009, 2009. a
Mülmenstädt, J., Sourdeval, O., Delanoë, J., and Quaas, J.:
Frequency of occurrence of rain from liquid-, mixed-, and ice-phase clouds
derived from A-Train satellite retrievals, Geophys. Res. Lett., 42,
6502–6509, https://doi.org/10.1002/2015GL064604, 2015. a
Nakajima, T., Higurashi, A., Kawamoto, K., and Penner, J. E.: A possible
correlation between satellite-derived cloud and aerosol microphysical
parameters, Geophys. Res. Lett., 28, 1171, https://doi.org/10.1029/2000GL012186, 2001. a
Neubauer, D., Christensen, M. W., Poulsen, C. A., and Lohmann, U.: Unveiling
aerosol–cloud interactions – Part 2: Minimising the effects of aerosol
swelling and wet scavenging in ECHAM6-HAM2 for comparison to satellite data,
Atmos. Chem. Phys., 17, 13165–13185,
https://doi.org/10.5194/acp-17-13165-2017, 2017. a, b
Nicholls, S.: A Model of Drizzle Growth In Warm, Turbulent, Stratiform
Clouds, Q. J. Roy. Meteor. Soc., 113, 1141–1170,
https://doi.org/10.1002/qj.49711347805, 1987. a
Noone, K. J., Johnson, D. W., Taylor, J. P., Ferek, R. J., Garrett, T.,
Hobbs, P. V., Durkee, P. A., Nielsen, K., Öström, E., O'Dowd, C.,
Smith, M. H., Russell, L. M., Flagan, R. C., Seinfeld, J. H., de, B. L., van,
G. R. E., Hudson, J. G., Brooks, I., Gasparovic, R. F., and Pockalny, R. A.:
A Case Study of Ship Track Formation in a Polluted Marine Boundary Layer., J.
Atmos. Sci., 57, 2748–2764,
https://doi.org/10.1175/1520-0469(2000)057<2748:ACSOST>2.0.CO;2, 2000. a
Oreopoulos, L., Cho, N., Lee, D., Kato, S., and Huffman, G. J.: An
examination of the nature of global MODIS cloud regimes, J. Geophys. Res.,
119, 8362–8383, https://doi.org/10.1002/2013JD021409, 2014. a
Painemal, D. and Zuidema, P.: Assessment of MODIS cloud effective radius
and optical thickness retrievals over the Southeast Pacific with
VOCALS-REx in situ measurements, J. Geophys. Res., 116, D24206,
https://doi.org/10.1029/2011JD016155, 2011. a
Pawlowska, H., Brenguier, J., and Burnet, F.: Microphysical properties of
stratocumulus clouds, Atmos. Res., 55, 15–33,
https://doi.org/10.1016/S0169-8095(00)00054-5, 2000. a
Pearl, J.: A Probabilistic Calculus of Actions, in: Uncertainty in Artificial
Intelligence 10, edited by: Lopez de Mantaras, R. and Poole, D., Morgan
Kaufmann, San Mateo, CA, 454–462, https://doi.org/10.1016/B978-1-55860-332-5.50062-6,
1994. a, b
Pincus, R. and Baker, M.: Effects of precipitation on the albedo
susceptibility of clouds in the marine boundary layer, Nature, 372, 250–252,
1994. a
Quaas, J., Boucher, O., and Lohmann, U.: Constraining the total aerosol
indirect effect in the LMDZ and ECHAM4 GCMs using MODIS satellite data,
Atmos. Chem. Phys., 6, 947–955, https://doi.org/10.5194/acp-6-947-2006,
2006. a, b
Quaas, J., Boucher, O., Bellouin, N., and Kinne, S.: Satellite-based estimate
of the direct and indirect aerosol climate forcing, J. Geophys. Res., 113,
D05204, https://doi.org/10.1029/2007JD008962, 2008. a, b
Quaas, J., Ming, Y., Menon, S., Takemura, T., Wang, M., Penner, J. E.,
Gettelman, A., Lohmann, U., Bellouin, N., Boucher, O., Sayer, A. M., Thomas,
G. E., McComiskey, A., Feingold, G., Hoose, C., Kristjánsson, J. E., Liu,
X., Balkanski, Y., Donner, L. J., Ginoux, P. A., Stier, P., Grandey, B.,
Feichter, J., Sednev, I., Bauer, S. E., Koch, D., Grainger, R. G.,
Kirkevåg, A., Iversen, T., Seland, Ø., Easter, R., Ghan, S. J., Rasch,
P. J., Morrison, H., Lamarque, J.-F., Iacono, M. J., Kinne, S., and Schulz,
M.: Aerosol indirect effects – general circulation model intercomparison and
evaluation with satellite data, Atmos. Chem. Phys., 9, 8697–8717,
https://doi.org/10.5194/acp-9-8697-2009, 2009. a
Quaas, J., Stevens, B., Stier, P., and Lohmann, U.: Interpreting the cloud
cover – aerosol optical depth relationship found in satellite data using a
general circulation model, Atmos. Chem. Phys., 10, 6129–6135,
https://doi.org/10.5194/acp-10-6129-2010, 2010. a, b
Sato, Y., Goto, D., Michibata, T., Suzuki, K., Takemura, T., Tomita, H., and
Nakajima, T.: Aerosol effects on cloud water amounts were successfully
simulated by a global cloud-system resolving model, Nat. Commun., 9, 985,
https://doi.org/10.1038/s41467-018-03379-6, 2018. a, b, c, d
Seifert, P., Kunz, C., Baars, H., Ansmann, A., Bühl, J., Senf, F.,
Engelmann, R., Althausen, D., and Artaxo, P.: Seasonal variability of
heterogeneous ice formation in stratiform clouds over the Amazon Basin,
Geophys. Res. Lett., 42, 5587–5593, https://doi.org/10.1002/2015GL064068, 2015. a
Sekiguchi, M., Nakajima, T., Suzuki, K., Kawamoto, K., Higurashi, A.,
Rosenfeld, D., Sano, I., and Mukai, S.: A study of the direct and indirect
effects of aerosols using global satellite data sets of aerosol and cloud
parameters, J. Geophys. Res., 108, 4699, https://doi.org/10.1029/2002JD003359, 2003. a
Small, J. D., Chuang, P. Y., Feingold, G., and Jiang, H.: Can aerosol
decrease cloud lifetime?, Geophys. Res. Lett., 36, L16806,,
https://doi.org/10.1029/2009GL038888, 2009. a, b, c
Sourdeval, O., C.-Labonnote, L., Baran, A. J., Mülmenstädt, J., and
Brogniez, G.: A methodology for simultaneous retrieval of ice and liquid
water cloud properties – Part 2: Near-global retrievals and evaluation
against A-Train products, Q. J. Roy. Meteor. Soc., 142, 3063–3081,
https://doi.org/10.1002/qj.2889, 2016. a
Stevens, B., Fiedler, S., Kinne, S., Peters, K., Rast, S., Müsse, J.,
Smith, S. J., and Mauritsen, T.: MACv2-SP: a parameterization of
anthropogenic aerosol optical properties and an associated Twomey effect for
use in CMIP6, Geosci. Model Dev., 10, 433–452,
https://doi.org/10.5194/gmd-10-433-2017, 2017. a
Stevens, B., Fiedler, S., Kinne, S., Peters, K., Rast, S., Müsse, J.,
Smith, S. J., and Mauritsen, T.: MACv2-SP: a parameterization of
anthropogenic aerosol optical properties and an associated Twomey effect for
use in CMIP6, Geosci. Model Dev., 10, 433–452,
https://doi.org/10.5194/gmd-10-433-2017, 2017. a
Suzuki, K., Stephens, G. L., and Lebsock, M. D.: Aerosol effect on the warm
rain formation process: Satellite observations and modeling, J. Geophys.
Res., 118, 170–184, https://doi.org/10.1002/jgrd.50043, 2013. a
Toll, V., Christensen, M., Gassó, S., and Bellouin, N.: Volcano and Ship
Tracks Indicate Excessive Aerosol-Induced Cloud Water Increases in a Climate
Model, Geophys. Res. Lett., 44, 12,492–12,500, https://doi.org/10.1002/2017GL075280,
2017. a, b, c, d
Twomey, S.: Pollution and the planetary albedo, Atmos. Environ., 8,
1251–1256, https://doi.org/10.1016/0004-6981(74)90004-3, 1974. a, b
Várnai, T. and Marshak, A.: MODIS observations of enhanced clear sky
reflectance near clouds, Geophys. Res. Lett., 36, L6807,
https://doi.org/10.1029/2008GL037089, 2009. a
Wang, M., Ghan, S., Liu, X., L'Ecuyer, T. S., Zhang, K., Morrison, H.,
Ovchinnikov, M., Easter, R., Marchand, R., Chand, D., Qian, Y., and Penner,
J. E.: Constraining cloud lifetime effects of aerosols using A-Train
satellite observations, Geophys. Res. Lett., 39, L15709,
https://doi.org/10.1029/2012GL052204, 2012. a
Wang, S., Wang, Q., and Feingold, G.: Turbulence, Condensation, and Liquid
Water Transport in Numerically Simulated Nonprecipitating Stratocumulus
Clouds, J. Atmos. Sci., 60, 262–278,
https://doi.org/10.1175/1520-0469(2003)060<0262:TCALWT>2.0.CO;2, 2003. a, b
Warner, J.: The Microstructure of Cumulus Cloud: Part IV. The Effect on the
Droplet Spectrum of Mixing Between Cloud and Environment, J. Atmos. Sci., 30,
256–261, https://doi.org/10.1175/1520-0469(1973)030<0256:TMOCCP>2.0.CO;2, 1973. a
Wentz, F. and Meissner, T.: AMSR-E/Aqua L2B Global Swath Ocean Products
derived from Wentz Algorithm, Version 2.6,
https://doi.org/10.5067/AMSR-E/AE_OCEAN.002, 2004. a
Wielicki, B. A., Barkstrom, B. R., Harrison, E. F., Lee, R. B., Louis Smith,
G., and Cooper, J. E.: Clouds and the Earth's Radiant Energy System
(CERES): An Earth Observing System Experiment, B. Am. Meteorol. Soc., 77,
853–868, https://doi.org/10.1175/1520-0477(1996)077<0853:CATERE>2.0.CO;2, 1996. a
Szczodrak, M., Austin, P. H., and Krummel, P. B.: Variability of Optical
Depth and Effective Radius in Marine Stratocumulus Clouds, J. Atmos. Sci.,
58, 2912–2926, https://doi.org/10.1175/1520-0469(2001)058<2912:VOODAE>2.0.CO;2, 2001. a
Xue, H. and Feingold, G.: Large-Eddy Simulations of Trade Wind Cumuli:
Investigation of Aerosol Indirect Effects, J. Atmos. Sci., 63, 1605–1622,
https://doi.org/10.1175/JAS3706.1, 2006. a, b, c
Yuan, T., Remer, L. A., and Yu, H.: Microphysical, macrophysical and
radiative signatures of volcanic aerosols in trade wind cumulus observed by
the A-Train, Atmos. Chem. Phys., 11, 7119–7132,
https://doi.org/10.5194/acp-11-7119-2011, 2011. a, b
Yum, S. S., Wang, J., Liu, Y., Senum, G., Springston, S., McGraw, R., and
Yeom, J. M.: Cloud microphysical relationships and their implication on
entrainment and mixing mechanism for the stratocumulus clouds measured during
the VOCALS project, J. Geophys. Res., 120, 5047–5069,
https://doi.org/10.1002/2014JD022802, 2015. a, b
Zelinka, M. D., Andrews, T., Forster, P. M., and Taylor, K. E.: Quantifying
components of aerosol-cloud-radiation interactions in climate models, J.
Geophys. Res., 119, 7599–7615, https://doi.org/10.1002/2014JD021710, 2014. a
Zhang, L., Zhao, T., Gong, S., Kong, S., Tang, L., Liu, D., Wang, Y., Jin,
L., Shan, Y., Tan, C., Zhang, Y., and Guo, X.: Updated emission inventories
of power plants in simulating air quality during haze periods over East
China, Atmos. Chem. Phys., 18, 2065–2079,
https://doi.org/10.5194/acp-18-2065-2018, 2018. a
Zhang, Z. and Platnick, S.: An assessment of differences between cloud
effective particle radius retrievals for marine water clouds from three
MODIS spectral bands, J. Geophys. Res., 116, D20215,
https://doi.org/10.1029/2011JD016216, 2011. a, b
Short summary
The liquid water path (LWP) is the strongest control on cloud albedo, such that a small change in LWP can have a large radiative impact. By changing the droplet number concentration (Nd) aerosols may be able to change the LWP, but the sign and magnitude of the effect is unclear. This work uses satellite data to investigate the relationship between Nd and LWP at a global scale and in response to large aerosol perturbations, suggesting that a strong decrease in LWP at high Nd may be overestimated.
The liquid water path (LWP) is the strongest control on cloud albedo, such that a small change...
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