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Atmospheric Chemistry and Physics
An interactive open-access journal of the European Geosciences Union
Journal topic
- About
- Editorial board
- Articles
- Special issues
- Highlight articles
- Manuscript tracking
- Subscribe to alerts
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IF 5.414
5.958CiteScore
9.7SNIP 1.517
SJR 2.601
index 191h5-index 89
Abstracted/indexed
Abstracted/indexed
Volume 14, issue 4
Atmos. Chem. Phys., 14, 1973–1985, 2014
https://doi.org/10.5194/acp-14-1973-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/acp-14-1973-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 14, 1973–1985, 2014
https://doi.org/10.5194/acp-14-1973-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/acp-14-1973-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article 20 Feb 2014
Research article | 20 Feb 2014
Ice particles in the upper anvil regions of midlatitude continental thunderstorms: the case for frozen-drop aggregates
J. L. Stith et al.
Related authors
Junshik Um, Greg M. McFarquhar, Jeffrey L. Stith, Chang Hoon Jung, Seoung Soo Lee, Ji Yi Lee, Younghwan Shin, Yun Gon Lee, Yiseok Isaac Yang, Seong Soo Yum, Byung-Gon Kim, Joo Wan Cha, and A-Reum Ko
Atmos. Chem. Phys., 18, 16915–16930, https://doi.org/10.5194/acp-18-16915-2018, https://doi.org/10.5194/acp-18-16915-2018, 2018
Short summary
Short summary
During the 2012 Deep Convective Clouds and Chemistry experiment upper anvils of two storms were sampled. The occurrence of well-defined pristine crystals was low in the anvils, while single frozen droplets and frozen droplet aggregates (FDAs) were the dominant habits. A new algorithm was developed to automatically identify the number, size, and relative position of element frozen droplets within FDAs. The morphological characteristics of FDAs were compared with those of black carbon aggregates.
Jeffrey L. Stith, Brett Basarab, Steven A. Rutledge, and Andrew Weinheimer
Atmos. Chem. Phys., 16, 2243–2254, https://doi.org/10.5194/acp-16-2243-2016, https://doi.org/10.5194/acp-16-2243-2016, 2016
Short summary
Short summary
Lightning-produced NOx and ice particles were studied using airborne measurements in thunderstorm anvil clouds during the Deep Convective Clouds and Chemistry experiment (DC3). These data were compared with radar and Lightning Mapping Array (LMA) measurements. A characteristic signature was found in three anvils that relates the occurrence of frozen cloud droplets and aggregates of frozen droplets to the presence of lightning-produced NOx in these storms.
Alexei Korolev, Ivan Heckman, Mengistu Wolde, Andrew S. Ackerman, Ann M. Fridlind, Luis A. Ladino, R. Paul Lawson, Jason Milbrandt, and Earle Williams
Atmos. Chem. Phys., 20, 1391–1429, https://doi.org/10.5194/acp-20-1391-2020, https://doi.org/10.5194/acp-20-1391-2020, 2020
Short summary
Short summary
This study attempts identification of mechanisms of secondary ice production (SIP) based on the observation of small faceted ice crystals. It was found that in both mesoscale convective systems and frontal clouds, SIP was observed right above the melting layer and extended to the higher altitudes with colder temperatures. A principal conclusion of this work is that the freezing drop shattering mechanism is plausibly accounting for the measured ice concentrations in the observed condition.
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. Discuss., https://doi.org/10.5194/acp-2020-40, https://doi.org/10.5194/acp-2020-40, 2020
Preprint under review for ACP
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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. The in-situ data give insights into mid-latitudes and tropics, while a global overview is provided from satellite. Further, examplary radiative characteristics of cirrus types are shown.
Junshik Um, Greg M. McFarquhar, Jeffrey L. Stith, Chang Hoon Jung, Seoung Soo Lee, Ji Yi Lee, Younghwan Shin, Yun Gon Lee, Yiseok Isaac Yang, Seong Soo Yum, Byung-Gon Kim, Joo Wan Cha, and A-Reum Ko
Atmos. Chem. Phys., 18, 16915–16930, https://doi.org/10.5194/acp-18-16915-2018, https://doi.org/10.5194/acp-18-16915-2018, 2018
Short summary
Short summary
During the 2012 Deep Convective Clouds and Chemistry experiment upper anvils of two storms were sampled. The occurrence of well-defined pristine crystals was low in the anvils, while single frozen droplets and frozen droplet aggregates (FDAs) were the dominant habits. A new algorithm was developed to automatically identify the number, size, and relative position of element frozen droplets within FDAs. The morphological characteristics of FDAs were compared with those of black carbon aggregates.
Armin Afchine, Christian Rolf, Anja Costa, Nicole Spelten, Martin Riese, Bernhard Buchholz, Volker Ebert, Romy Heller, Stefan Kaufmann, Andreas Minikin, Christiane Voigt, Martin Zöger, Jessica Smith, Paul Lawson, Alexey Lykov, Sergey Khaykin, and Martina Krämer
Atmos. Meas. Tech., 11, 4015–4031, https://doi.org/10.5194/amt-11-4015-2018, https://doi.org/10.5194/amt-11-4015-2018, 2018
Short summary
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The ice water content (IWC) of cirrus clouds is an essential parameter that determines their radiative properties and is thus important for climate simulations. Experimental investigations of IWCs measured on board research aircraft reveal that their accuracy is influenced by the sampling position. IWCs detected at the aircraft roof deviate significantly from wing, side or bottom IWCs. The reasons are deflections of the gas streamlines and ice particle trajectories behind the aircraft cockpit.
Cynthia H. Twohy, Gavin R. McMeeking, Paul J. DeMott, Christina S. McCluskey, Thomas C. J. Hill, Susannah M. Burrows, Gourihar R. Kulkarni, Meryem Tanarhte, Durga N. Kafle, and Darin W. Toohey
Atmos. Chem. Phys., 16, 8205–8225, https://doi.org/10.5194/acp-16-8205-2016, https://doi.org/10.5194/acp-16-8205-2016, 2016
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Fluorescent biological aerosol particles were measured in autumn over the continental United States at a variety of altitudes and temperatures, spanning the atmospheric boundary layer to the upper troposphere. Number concentrations of these particles generally decreased with height but were most variable at middle altitudes, above the boundary layer. This corresponds to the temperature range where biological particles may be more important than mineral dust at nucleating ice in clouds.
Ann M. Fridlind, Rachel Atlas, Bastiaan van Diedenhoven, Junshik Um, Greg M. McFarquhar, Andrew S. Ackerman, Elisabeth J. Moyer, and R. Paul Lawson
Atmos. Chem. Phys., 16, 7251–7283, https://doi.org/10.5194/acp-16-7251-2016, https://doi.org/10.5194/acp-16-7251-2016, 2016
Short summary
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Images of crystals within mid-latitude cirrus clouds are used to derive consistent ice physical and optical properties for a detailed cloud microphysics model, including size-dependent mass, projected area, and fall speed. Based on habits found, properties are derived for bullet rosettes, their aggregates, and crystals with irregular shapes. Derived bullet rosette fall speeds are substantially greater than reported in past studies, owing to differences in mass, area, or diameter representation.
Jeffrey L. Stith, Brett Basarab, Steven A. Rutledge, and Andrew Weinheimer
Atmos. Chem. Phys., 16, 2243–2254, https://doi.org/10.5194/acp-16-2243-2016, https://doi.org/10.5194/acp-16-2243-2016, 2016
Short summary
Short summary
Lightning-produced NOx and ice particles were studied using airborne measurements in thunderstorm anvil clouds during the Deep Convective Clouds and Chemistry experiment (DC3). These data were compared with radar and Lightning Mapping Array (LMA) measurements. A characteristic signature was found in three anvils that relates the occurrence of frozen cloud droplets and aggregates of frozen droplets to the presence of lightning-produced NOx in these storms.
J. Um, G. M. McFarquhar, Y. P. Hong, S.-S. Lee, C. H. Jung, R. P. Lawson, and Q. Mo
Atmos. Chem. Phys., 15, 3933–3956, https://doi.org/10.5194/acp-15-3933-2015, https://doi.org/10.5194/acp-15-3933-2015, 2015
Short summary
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Dimensions of ice crystals increased with an increase in temperature and the L-W relationships of crystals with a given L depended heavily on temperature, whereas the aspect ratio depended only weakly on temperature. The relative frequency of occurrence of plates was much larger in anvil clouds compared to that of columnar crystals (i.e., columns and bullet rosettes), whereas the relative occurrence frequency of columnar crystals was much larger in non-anvil clouds.
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
A. Moharreri, L. Craig, P. Dubey, D. C. Rogers, and S. Dhaniyala
Atmos. Meas. Tech., 7, 3085–3093, https://doi.org/10.5194/amt-7-3085-2014, https://doi.org/10.5194/amt-7-3085-2014, 2014
S. W. Dorsi, L. E. Kalnajs, D. W. Toohey, and L. M. Avallone
Atmos. Meas. Tech., 7, 215–223, https://doi.org/10.5194/amt-7-215-2014, https://doi.org/10.5194/amt-7-215-2014, 2014
C. H. Twohy, J. R. Anderson, D. W. Toohey, M. Andrejczuk, A. Adams, M. Lytle, R. C. George, R. Wood, P. Saide, S. Spak, P. Zuidema, and D. Leon
Atmos. Chem. Phys., 13, 2541–2562, https://doi.org/10.5194/acp-13-2541-2013, https://doi.org/10.5194/acp-13-2541-2013, 2013
Related subject area
Subject: Clouds and Precipitation | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)
Ice-supersaturated air masses in the northern mid-latitudes from regular in situ observations by passenger aircraft: vertical distribution, seasonality and tropospheric fingerprint
Supercooled drizzle development in response to semi-coherent vertical velocity fluctuations within an orographic-layer cloud
Stratocumulus cloud clearings: statistics from satellites, reanalysis models, and airborne measurements
Supercooled liquid water cloud observed, analysed, and modelled at the top of the planetary boundary layer above Dome C, Antarctica
Open cells exhibit weaker entrainment of free-tropospheric biomass burning aerosol into the south-east Atlantic boundary layer
Small ice particles at slightly supercooled temperatures in tropical maritime convection
Statistical analysis of ice microphysical properties in tropical mesoscale convective systems derived from cloud radar and in situ microphysical observations
Biomass burning aerosol as a modulator of the droplet number in the southeast Atlantic region
Conceptual model of diurnal cycle of low-level stratiform clouds over southern West Africa
The structure of turbulence and mixed-phase cloud microphysics in a highly supercooled altocumulus cloud
Characterization of aerosol particles at Cabo Verde close to sea level and at the cloud level – Part 2: Ice-nucleating particles in air, cloud and seawater
A new look at the environmental conditions favorable to secondary ice production
Spatial and temporal variability in the ice-nucleating ability of alpine snowmelt and extension to frozen cloud fraction
Evaluation of hygroscopic cloud seeding in liquid-water clouds: a feasibility study
The impact of fluctuations and correlations in droplet growth by collision–coalescence revisited – Part 2: Observational evidence of gel formation in warm clouds
The diurnal cycle of the smoky marine boundary layer observed during August in the remote southeast Atlantic
Characterization of aerosol properties at Cyprus, focusing on cloud condensation nuclei and ice-nucleating particles
Subsiding shells and the distribution of up- and downdraughts in warm cumulus clouds over land
Sensitivity of GPS tropospheric estimates to mesoscale convective systems in West Africa
The sensitivity of oceanic precipitation to sea surface temperature
Aerosol influences on low-level clouds in the West African monsoon
Supercooled liquid fogs over the central Greenland Ice Sheet
Droplet inhomogeneity in shallow cumuli: the effects of in-cloud location and aerosol number concentration
On the distinctiveness of observed oceanic raindrop distributions
Ice-nucleating particles in a coastal tropical site
Mixed-phase orographic cloud microphysics during StormVEx and IFRACS
Classification of Arctic multilayer clouds using radiosonde and radar data in Svalbard
Experimental study of the aerosol impact on fog microphysics
Contrasting local and long-range-transported warm ice-nucleating particles during an atmospheric river in coastal California, USA
A novel approach for characterizing the variability in mass–dimension relationships: results from MC3E
New type of evidence for secondary ice formation at around −15 °C in mixed-phase clouds
Analyses of temperature and precipitation in the Indian Jammu and Kashmir region for the 1980–2016 period: implications for remote influence and extreme events
Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017
Arctic ice clouds over northern Sweden: microphysical properties studied with the Balloon-borne Ice Cloud particle Imager B-ICI
In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic
Microphysical characteristics of frozen droplet aggregates from deep convective clouds
Additional global climate cooling by clouds due to ice crystal complexity
Observations of the microphysical evolution of convective clouds in the southwest of the United Kingdom
Time-dependent entrainment of smoke presents an observational challenge for assessing aerosol–cloud interactions over the southeast Atlantic Ocean
Observed aerosol suppression of cloud ice in low-level Arctic mixed-phase clouds
Cloud vertical structure over a tropical station obtained using long-term high-resolution radiosonde measurements
Statistical analysis of contrail to cirrus evolution during the Contrail and Cirrus Experiment (CONCERT)
The Green Ocean: precipitation insights from the GoAmazon2014/5 experiment
Impact of surface and near-surface processes on ice crystal concentrations measured at mountain-top research stations
Aerosol–fog interaction and the transition to well-mixed radiation fog
Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA
Concentration and variability of ice nuclei in the subtropical maritime boundary layer
An overview of the diurnal cycle of the atmospheric boundary layer during the West African monsoon season: results from the 2016 observational campaign
Tropical continental downdraft characteristics: mesoscale systems versus unorganized convection
Illustration of microphysical processes in Amazonian deep convective clouds in the gamma phase space: introduction and potential applications
Andreas Petzold, Patrick Neis, Mihal Rütimann, Susanne Rohs, Florian Berkes, Herman G. J. Smit, Martina Krämer, Nicole Spelten, Peter Spichtinger, Philippe Nédélec, and Andreas Wahner
Atmos. Chem. Phys., 20, 8157–8179, https://doi.org/10.5194/acp-20-8157-2020, https://doi.org/10.5194/acp-20-8157-2020, 2020
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The first analysis of 15 years of global-scale water vapour and relative humidity observations by passenger aircraft in the MOZAIC and IAGOS programmes resolves detailed features of water vapour and ice-supersaturated air in the mid-latitude tropopause. Key results provide in-depth insight into seasonal and regional variability and chemical signatures of ice-supersaturated air masses, including trend analyses, and show a close link to cirrus clouds and their highly important effects on climate.
Adam Majewski and Jeffrey R. French
Atmos. Chem. Phys., 20, 5035–5054, https://doi.org/10.5194/acp-20-5035-2020, https://doi.org/10.5194/acp-20-5035-2020, 2020
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The study reports formation of supercooled drizzle drops in response to repeating kilometer-wide updrafts and downdrafts within a mixed-phase, mountain-layer cloud containing very little ice despite cold cloud top temperatures (T ~ -30°C). The discrete, embedded hydrometeor growth layers and downwind transition to drizzle production at cloud top indicates the relative importance of kinematic mechanisms in determining the location of precipitation development in cloud.
Hossein Dadashazar, Ewan Crosbie, Mohammad S. Majdi, Milad Panahi, Mohammad A. Moghaddam, Ali Behrangi, Michael Brunke, Xubin Zeng, Haflidi H. Jonsson, and Armin Sorooshian
Atmos. Chem. Phys., 20, 4637–4665, https://doi.org/10.5194/acp-20-4637-2020, https://doi.org/10.5194/acp-20-4637-2020, 2020
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Clearings in the marine-boundary-layer (MBL) cloud deck of the Pacific Ocean were studied. Remote sensing, reanalysis, and airborne data were used along with machine-learning modeling to characterize the spatiotemporal nature of clearings and factors governing their growth. The most significant implications of our results are linked to modeling of fog and MBL clouds, with implications for societal and environmental issues like climate, military operations, transportation, and coastal ecology.
Philippe Ricaud, Massimo Del Guasta, Eric Bazile, Niramson Azouz, Angelo Lupi, Pierre Durand, Jean-Luc Attié, Dana Veron, Vincent Guidard, and Paolo Grigioni
Atmos. Chem. Phys., 20, 4167–4191, https://doi.org/10.5194/acp-20-4167-2020, https://doi.org/10.5194/acp-20-4167-2020, 2020
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Thin (~ 100 m) supercooled liquid water (SLW, water staying in liquid phase below 0 °C) clouds have been detected, analysed, and modelled over the Dome C (Concordia, Antarctica) station during the austral summer 2018–2019 using observations and meteorological analyses. The SLW clouds were observed at the top of the planetary boundary layer and the SLW content was always strongly underestimated by the model indicating an incorrect simulation of the surface energy budget of the Antarctic Plateau.
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.
Gary Lloyd, Thomas Choularton, Keith Bower, Jonathan Crosier, Martin Gallagher, Michael Flynn, James Dorsey, Dantong Liu, Jonathan W. Taylor, Oliver Schlenczek, Jacob Fugal, Stephan Borrmann, Richard Cotton, Paul Field, and Alan Blyth
Atmos. Chem. Phys., 20, 3895–3904, https://doi.org/10.5194/acp-20-3895-2020, https://doi.org/10.5194/acp-20-3895-2020, 2020
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Measurements of liquid and ice cloud particles were made using an aircraft to penetrate fresh growing convective clouds in the tropical Atlantic. We found small ice particles at surprisingly high temperatures just below freezing. At colder temperatures secondary ice processes rapidly generated high concentrations of ice crystals.
Emmanuel Fontaine, Alfons Schwarzenboeck, Delphine Leroy, Julien Delanoë, Alain Protat, Fabien Dezitter, John Walter Strapp, and Lyle Edward Lilie
Atmos. Chem. Phys., 20, 3503–3553, https://doi.org/10.5194/acp-20-3503-2020, https://doi.org/10.5194/acp-20-3503-2020, 2020
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This study investigates properties of ice hydrometeors (shape, concentration, density, and size) in deep convective systems. The analysis focuses on similarities and differences over four locations in the tropical troposphere. It shows that measurements as a function of temperature and radar reflectivity factors tend to be similar in the four types of deep convective systems when concentrations of ice are larger than 0.1 g m-3.
Mary Kacarab, K. Lee Thornhill, Amie Dobracki, Steven G. Howell, Joseph R. O'Brien, Steffen Freitag, Michael R. Poellot, Robert Wood, Paquita Zuidema, Jens Redemann, and Athanasios Nenes
Atmos. Chem. Phys., 20, 3029–3040, https://doi.org/10.5194/acp-20-3029-2020, https://doi.org/10.5194/acp-20-3029-2020, 2020
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We find that extensive biomass burning aerosol plumes from southern Africa can profoundly influence clouds in the southeastern Atlantic. Concurrent variations in vertical velocity, however, are found to magnify the relationship between boundary layer aerosol and the cloud droplet number. Neglecting these covariances may strongly bias the sign and magnitude of aerosol impacts on the cloud droplet number.
Fabienne Lohou, Norbert Kalthoff, Bianca Adler, Karmen Babić, Cheikh Dione, Marie Lothon, Xabier Pedruzo-Bagazgoitia, and Maurin Zouzoua
Atmos. Chem. Phys., 20, 2263–2275, https://doi.org/10.5194/acp-20-2263-2020, https://doi.org/10.5194/acp-20-2263-2020, 2020
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A conceptual model of the low-level stratiform clouds (LLSCs), which develop almost every night in southern West Africa, is built with the dataset acquired during the DACCIWA (Dynamics Aerosol Chemistry Cloud Interactions in West Africa) ground-based field experiment. Several processes occur during the four phases composing this diurnal cycle: the cooling of the air until saturation (stable and jet phases), LLSC and low-level jet interactions (stratus phase), and LLSC breakup (convective phase).
Paul A. Barrett, Alan Blyth, Philip R. A. Brown, and Steven J. Abel
Atmos. Chem. Phys., 20, 1921–1939, https://doi.org/10.5194/acp-20-1921-2020, https://doi.org/10.5194/acp-20-1921-2020, 2020
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Here we present new in situ observations from altocumulus clouds made with a research aircraft. By carefully measuring the cloud top height, we are able to study the turbulence and cloud properties in high vertical resolution, something not presented before. The clouds contain both ice particles and liquid drops, even though the temperature is −30 °C. These measurements will hopefully assist future developers of climate models to verify and assess the performance of simulations.
Xianda Gong, Heike Wex, Manuela van Pinxteren, Nadja Triesch, Khanneh Wadinga Fomba, Jasmin Lubitz, Christian Stolle, Tiera-Brandy Robinson, Thomas Müller, Hartmut Herrmann, and Frank Stratmann
Atmos. Chem. Phys., 20, 1451–1468, https://doi.org/10.5194/acp-20-1451-2020, https://doi.org/10.5194/acp-20-1451-2020, 2020
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In this study, we examined number concentrations of ice nucleating particles (INPs) at Cabo Verde in the oceanic sea surface microlayer and underlying seawater, in the air close to both sea level and cloud level, and in cloud water. The results show that most INPs are supermicron in size, that INP number concentrations in air fit well to those in cloud water and that sea spray aerosols at maximum contributed a small fraction of all INPs in the air at Cabo Verde.
Alexei Korolev, Ivan Heckman, Mengistu Wolde, Andrew S. Ackerman, Ann M. Fridlind, Luis A. Ladino, R. Paul Lawson, Jason Milbrandt, and Earle Williams
Atmos. Chem. Phys., 20, 1391–1429, https://doi.org/10.5194/acp-20-1391-2020, https://doi.org/10.5194/acp-20-1391-2020, 2020
Short summary
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This study attempts identification of mechanisms of secondary ice production (SIP) based on the observation of small faceted ice crystals. It was found that in both mesoscale convective systems and frontal clouds, SIP was observed right above the melting layer and extended to the higher altitudes with colder temperatures. A principal conclusion of this work is that the freezing drop shattering mechanism is plausibly accounting for the measured ice concentrations in the observed condition.
Killian P. Brennan, Robert O. David, and Nadine Borduas-Dedekind
Atmos. Chem. Phys., 20, 163–180, https://doi.org/10.5194/acp-20-163-2020, https://doi.org/10.5194/acp-20-163-2020, 2020
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To contribute to our understanding of the liquid water-to-ice ratio in mixed-phase clouds, this study provides a spatial and temporal dataset of ice-nucleating particle (INP) concentrations in meltwater of 88 snow samples across 17 locations in the Swiss Alps. The impact of altitude, terrain, time since last snowfall and depth on freezing temperatures was also investigated. The measured INP concentrations provide an estimate of cloud glaciation temperatures important for cloud lifetime.
Fei Wang, Zhanqing Li, Qi Jiang, Gaili Wang, Shuo Jia, Jing Duan, and Yuquan Zhou
Atmos. Chem. Phys., 19, 14967–14977, https://doi.org/10.5194/acp-19-14967-2019, https://doi.org/10.5194/acp-19-14967-2019, 2019
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Though many laboratory, modeling, and field experimental studies on cloud seeding have been conducted for more than a half-century, assessing the effectiveness of cloud seeding is still very challenging due to the notorious difficulties in gaining convincing scientific evidences. The goals of this study are to evaluate any consequence of aircraft hygroscopic seeding and to develop a feasible method for analyzing the cloud seeding effect for stratocumulus clouds.
Lester Alfonso, Graciela B. Raga, and Darrel Baumgardner
Atmos. Chem. Phys., 19, 14917–14932, https://doi.org/10.5194/acp-19-14917-2019, https://doi.org/10.5194/acp-19-14917-2019, 2019
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The aim of this paper is to find some observational evidence of gel formation in clouds, by analyzing the distribution of the largest droplet at an early stage of cloud formation, and to show that the mass of the gel (
lucky droplet) is a mixture of Gaussian and Gumbel distributions. The results obtained may help advance the understanding of precipitation formation and are a novel application of the theory of critical phenomena in cloud physics.
Jianhao Zhang and Paquita Zuidema
Atmos. Chem. Phys., 19, 14493–14516, https://doi.org/10.5194/acp-19-14493-2019, https://doi.org/10.5194/acp-19-14493-2019, 2019
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Boundary layer (BL) semi-direct effects in the remote SE Atlantic are investigated using LASIC field measurements and satellite retrievals. Low-cloud cover and cloud liquid water path decrease with increasing smoke loadings in the BL. Daily-mean surface-based mixed layer is warmer by 0.5 K, moisture accumulates near the surface throughout the night, and the BL deepens by 200 m, with LWPs and cloud top heights increasing, in the sunlit morning hours, as part of the smoke-altered BL diurnal cycle.
Xianda Gong, Heike Wex, Thomas Müller, Alfred Wiedensohler, Kristina Höhler, Konrad Kandler, Nan Ma, Barbara Dietel, Thea Schiebel, Ottmar Möhler, and Frank Stratmann
Atmos. Chem. Phys., 19, 10883–10900, https://doi.org/10.5194/acp-19-10883-2019, https://doi.org/10.5194/acp-19-10883-2019, 2019
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For the diverse aerosol on Cyprus, we found the following: new particle formation can be a source of cloud condensation nuclei. Particle hygroscopicity showed that particles ~<100 nm contained mostly organic material, while larger ones were more hygroscopic. Two separate methods obtained similar concentrations of ice-nucleating particles (INP), with mostly no evidence of a local origin. Different parameterizations overestimated INP concentration in this rather polluted region.
Christian Mallaun, Andreas Giez, Georg J. Mayr, and Mathias W. Rotach
Atmos. Chem. Phys., 19, 9769–9786, https://doi.org/10.5194/acp-19-9769-2019, https://doi.org/10.5194/acp-19-9769-2019, 2019
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This study presents airborne measurements in shallow convection over land to investigate the dynamic properties of clouds focusing on possible narrow downdraughts in the surrounding of the clouds. A characteristic narrow downdraught region (
subsiding shell) is found directly outside the cloud borders for the mean vertical wind distribution. The
subsiding shellresults from the distribution of the highly variable updraughts and downdraughts in the near vicinity of the cloud.
Samuel Nahmani, Olivier Bock, and Françoise Guichard
Atmos. Chem. Phys., 19, 9541–9561, https://doi.org/10.5194/acp-19-9541-2019, https://doi.org/10.5194/acp-19-9541-2019, 2019
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A mesoscale convective system (MCS) is a cloud system that occurs in connection with an ensemble of thunderstorms and produces a contiguous precipitation area of the order of 100 km or more. Numerous questions related to MCSs remain poorly answered (e.g., their life cycle, and interactions between physical processes and atmospheric circulations). This work shows how a GPS technique can provide relevant and complementary information on MCSs passing over or in the vicinity of observation stations.
Jörg Burdanowitz, Stefan A. Buehler, Stephan Bakan, and Christian Klepp
Atmos. Chem. Phys., 19, 9241–9252, https://doi.org/10.5194/acp-19-9241-2019, https://doi.org/10.5194/acp-19-9241-2019, 2019
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Sensitivity of precipitation to sea surface temperature over the ocean determines how precipitation potentially changes in a warming climate. This relationship has hardly been studied over ocean due to a lack of long-term oceanic data. Our study shows how the precipitation sensitivity depends on resolution, what process limits oceanic precipitation and how the event duration depends on temperature. This provides valuable information for future climate observations, modeling and understanding.
Jonathan W. Taylor, Sophie L. Haslett, Keith Bower, Michael Flynn, Ian Crawford, James Dorsey, Tom Choularton, Paul J. Connolly, Valerian Hahn, Christiane Voigt, Daniel Sauer, Régis Dupuy, Joel Brito, Alfons Schwarzenboeck, Thierry Bourriane, Cyrielle Denjean, Phil Rosenberg, Cyrille Flamant, James D. Lee, Adam R. Vaughan, Peter G. Hill, Barbara Brooks, Valéry Catoire, Peter Knippertz, and Hugh Coe
Atmos. Chem. Phys., 19, 8503–8522, https://doi.org/10.5194/acp-19-8503-2019, https://doi.org/10.5194/acp-19-8503-2019, 2019
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Low-level clouds cover a wide area of southern West Africa (SWA) and play an important role in the region's climate, reflecting sunlight away from the surface. We performed aircraft measurements of aerosols and clouds over SWA during the 2016 summer monsoon and found pollution, and polluted clouds, across the whole region. Smoke from biomass burning in Central Africa is transported to West Africa, causing a polluted background which limits the effect of local pollution on cloud properties.
Christopher J. Cox, David C. Noone, Max Berkelhammer, Matthew D. Shupe, William D. Neff, Nathaniel B. Miller, Von P. Walden, and Konrad Steffen
Atmos. Chem. Phys., 19, 7467–7485, https://doi.org/10.5194/acp-19-7467-2019, https://doi.org/10.5194/acp-19-7467-2019, 2019
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Fogs are frequently reported by observers on the Greenland Ice Sheet. Fogs play a role in the hydrological and energetic balances of the ice sheet surface, but as yet the properties of Greenland fogs are not well known. We observed fogs in all months from Summit Station for 2 years and report their properties. Annually, fogs impart a slight warming to the surface and a case study suggests that they are particularly influential by providing insulation during the coldest part of the day in summer.
Dillon S. Dodson and Jennifer D. Small Griswold
Atmos. Chem. Phys., 19, 7297–7317, https://doi.org/10.5194/acp-19-7297-2019, https://doi.org/10.5194/acp-19-7297-2019, 2019
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This work looks at how the amount of aerosols contained in cloud affects the spatial orientation of the cloud droplets. Droplet orientation is important because it can lead to changes in the amount of time it takes precipitation to form. The results show that the aerosol amount does not have any effect on the droplet orientation. It is found however that the droplets are spaced closer together (there is increased droplet clustering) at cloud edge and top, as compared to center and bottom.
David Ian Duncan, Patrick Eriksson, Simon Pfreundschuh, Christian Klepp, and Daniel C. Jones
Atmos. Chem. Phys., 19, 6969–6984, https://doi.org/10.5194/acp-19-6969-2019, https://doi.org/10.5194/acp-19-6969-2019, 2019
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Raindrop size distributions have not been systematically studied over the oceans but are significant for remotely sensing, assimilating, and modeling rain. Here we investigate raindrop populations with new global in situ data, compare them against satellite estimates, and explore a new technique to classify the shapes of these distributions. The results indicate the inadequacy of a commonly assumed shape in some regions and the sizable impact of shape variability on satellite measurements.
Luis A. Ladino, Graciela B. Raga, Harry Alvarez-Ospina, Manuel A. Andino-Enríquez, Irma Rosas, Leticia Martínez, Eva Salinas, Javier Miranda, Zyanya Ramírez-Díaz, Bernardo Figueroa, Cedric Chou, Allan K. Bertram, Erika T. Quintana, Luis A. Maldonado, Agustín García-Reynoso, Meng Si, and Victoria E. Irish
Atmos. Chem. Phys., 19, 6147–6165, https://doi.org/10.5194/acp-19-6147-2019, https://doi.org/10.5194/acp-19-6147-2019, 2019
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This study presents results obtained during a field campaign conducted in the tropical village of Sisal located on the coast of the Gulf of Mexico. Air masses arriving in Sisal during the passage of cold fronts have surprisingly higher ice-nucleating particle (INP) concentrations than the campaign average. The high concentrations of INPs at T > −15 C and the supermicron size of the INPs suggest that biological particles may have been a significant contributor to the INP population in Sisal.
Douglas H. Lowenthal, A. Gannet Hallar, Robert O. David, Ian B. McCubbin, Randolph D. Borys, and Gerald G. Mace
Atmos. Chem. Phys., 19, 5387–5401, https://doi.org/10.5194/acp-19-5387-2019, https://doi.org/10.5194/acp-19-5387-2019, 2019
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Snow and liquid cloud particles were measured during the StormVEx and IFRACS programs at Storm Peak Lab to better understand snow formation in wintertime mountain clouds. We found significant interactions between the ice and liquid phases of the cloud. A relationship between large droplet and small ice crystal concentrations suggested snow formation by droplet freezing. Blowing snow can bias surface measurements, but its effect was ambiguous, calling for further work on this issue.
Maiken Vassel, Luisa Ickes, Marion Maturilli, and Corinna Hoose
Atmos. Chem. Phys., 19, 5111–5126, https://doi.org/10.5194/acp-19-5111-2019, https://doi.org/10.5194/acp-19-5111-2019, 2019
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Multilayer clouds are coexisting clouds at different heights. We evaluate measurements and find that Arctic multilayer clouds occur in 29 % of the investigated days at Ny-Ålesund, Svalbard. Multilayer clouds can interact by ice crystals falling from the upper cloud into the lower cloud. This is possible in 23 % of the investigated days, and in 9 % it is not possible. Weather models are still error-prone in the Arctic and we suggest that multilayer clouds should be included more in future work.
Marie Mazoyer, Frédéric Burnet, Cyrielle Denjean, Gregory C. Roberts, Martial Haeffelin, Jean-Charles Dupont, and Thierry Elias
Atmos. Chem. Phys., 19, 4323–4344, https://doi.org/10.5194/acp-19-4323-2019, https://doi.org/10.5194/acp-19-4323-2019, 2019
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In situ microphysical measurements collected during 23 fog events at SIRTA (south of Paris) are examined here. An original iterative method based on the κ-Köhler theory has been used to compute statistics of their activation properties. Useful information is provided to constrain and validate numerical simulations. The paper demonstrates that supersaturation encountered in these fogs is too low to observe a correlation between concentrations of aerosols > 200 nm and droplet concentrations.
Andrew C. Martin, Gavin Cornwell, Charlotte M. Beall, Forest Cannon, Sean Reilly, Bas Schaap, Dolan Lucero, Jessie Creamean, F. Martin Ralph, Hari T. Mix, and Kimberly Prather
Atmos. Chem. Phys., 19, 4193–4210, https://doi.org/10.5194/acp-19-4193-2019, https://doi.org/10.5194/acp-19-4193-2019, 2019
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Aerosols that promote ice formation in clouds were investigated during an atmospheric river that caused significant rain in northern California. We found that biological particles produced by local terrestrial ecosystems greatly enhanced cloud ice when meteorology allowed for their injection to the storm. The local terrestrial particles had greater impact on clouds than particles transported from across the Pacific Ocean, lending additional insight to which aerosols are important for cloud ice.
Joseph A. Finlon, Greg M. McFarquhar, Stephen W. Nesbitt, Robert M. Rauber, Hugh Morrison, Wei Wu, and Pengfei Zhang
Atmos. Chem. Phys., 19, 3621–3643, https://doi.org/10.5194/acp-19-3621-2019, https://doi.org/10.5194/acp-19-3621-2019, 2019
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A new approach describing the relationship between ice crystal mass (m) and dimension (D) is derived, characterizing it as a set of
equally realizableparameters based on the natural variability in cloud conditions observed by aircraft over the Great Plains. Results from this approach address shortcomings of microphysical parameterization schemes and remote sensing retrievals that employ a single m–D relation for a given ice species or environment.
Claudia Mignani, Jessie M. Creamean, Lukas Zimmermann, Christine Alewell, and Franz Conen
Atmos. Chem. Phys., 19, 877–886, https://doi.org/10.5194/acp-19-877-2019, https://doi.org/10.5194/acp-19-877-2019, 2019
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A snow crystal can be generated from an ice nucleating particle or from an ice splinter. In this study we made use of the fact that snow crystals with a particular shape (dendrites) grow within a narrow temperature range (−12 to −17 °C) and can be analysed individually for the presence of an ice nucleating particle. Our direct approach revealed that only one in eight crystals contained such a particle and was of primary origin. The other crystals must have grown from ice splinters.
Sumira Nazir Zaz, Shakil Ahmad Romshoo, Ramkumar Thokuluwa Krishnamoorthy, and Yesubabu Viswanadhapalli
Atmos. Chem. Phys., 19, 15–37, https://doi.org/10.5194/acp-19-15-2019, https://doi.org/10.5194/acp-19-15-2019, 2019
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This paper is of first of its kind for the Jammu and Kashmir (western Himalayas) region, India. It shows the clear relation between the upper tropospheric Rossby wave activity (potential vorticity at the 350 K potential temperature and 200 mb level surface pressure) and the surface weather parameters (e.g., precipitation) over a period of 3 decades during 1980–2016. This indicates that the climatic weather pattern over the Kashmir region is influenced mostly by global climate change processes.
Erlend M. Knudsen, Bernd Heinold, Sandro Dahlke, Heiko Bozem, Susanne Crewell, Irina V. Gorodetskaya, Georg Heygster, Daniel Kunkel, Marion Maturilli, Mario Mech, Carolina Viceto, Annette Rinke, Holger Schmithüsen, André Ehrlich, Andreas Macke, Christof Lüpkes, and Manfred Wendisch
Atmos. Chem. Phys., 18, 17995–18022, https://doi.org/10.5194/acp-18-17995-2018, https://doi.org/10.5194/acp-18-17995-2018, 2018
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The paper describes the synoptic development during the ACLOUD/PASCAL airborne and ship-based field campaign near Svalbard in spring 2017. This development is presented using near-surface and upperair meteorological observations, satellite, and model data. We first present time series of these data, from which we identify and characterize three key periods. Finally, we put our observations in historical and regional contexts and compare our findings to other Arctic field campaigns.
Veronika Wolf, Thomas Kuhn, Mathias Milz, Peter Voelger, Martina Krämer, and Christian Rolf
Atmos. Chem. Phys., 18, 17371–17386, https://doi.org/10.5194/acp-18-17371-2018, https://doi.org/10.5194/acp-18-17371-2018, 2018
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Balloon-borne measurements of microphysical properties of Arctic ice clouds have been performed with an in situ particle imager and been analyzed for the first time with respect to how the ice particles have formed. Ice particle size, shape and number show large variations from cloud to cloud, which cannot be explained with local conditions only, and rather depend on conditions at cloud formation. Taking this into account when parametrizing ice cloud properties may improve retrievals and models.
Gary Lloyd, Thomas W. Choularton, Keith N. Bower, Martin W. Gallagher, Jonathan Crosier, Sebastian O'Shea, Steven J. Abel, Stuart Fox, Richard Cotton, and Ian A. Boutle
Atmos. Chem. Phys., 18, 17191–17206, https://doi.org/10.5194/acp-18-17191-2018, https://doi.org/10.5194/acp-18-17191-2018, 2018
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The work deals with cold weather outbreaks at high latitudes that often bring severe weather such as heavy snow, lightning and high winds but are poorly forecast by weather models. Here we made measurements of these events and the clouds associated with them using a research aircraft. We found that the properties of these clouds were often very different to what the models predicted, and these results can potentially be used to bring significant improvement to the forecasting of these events.
Junshik Um, Greg M. McFarquhar, Jeffrey L. Stith, Chang Hoon Jung, Seoung Soo Lee, Ji Yi Lee, Younghwan Shin, Yun Gon Lee, Yiseok Isaac Yang, Seong Soo Yum, Byung-Gon Kim, Joo Wan Cha, and A-Reum Ko
Atmos. Chem. Phys., 18, 16915–16930, https://doi.org/10.5194/acp-18-16915-2018, https://doi.org/10.5194/acp-18-16915-2018, 2018
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During the 2012 Deep Convective Clouds and Chemistry experiment upper anvils of two storms were sampled. The occurrence of well-defined pristine crystals was low in the anvils, while single frozen droplets and frozen droplet aggregates (FDAs) were the dominant habits. A new algorithm was developed to automatically identify the number, size, and relative position of element frozen droplets within FDAs. The morphological characteristics of FDAs were compared with those of black carbon aggregates.
Emma Järvinen, Olivier Jourdan, David Neubauer, Bin Yao, Chao Liu, Meinrat O. Andreae, Ulrike Lohmann, Manfred Wendisch, Greg M. McFarquhar, Thomas Leisner, and Martin Schnaiter
Atmos. Chem. Phys., 18, 15767–15781, https://doi.org/10.5194/acp-18-15767-2018, https://doi.org/10.5194/acp-18-15767-2018, 2018
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Using light diffraction it is possible to detect microscopic features within ice particles that have not yet been fully characterized. Here, this technique was applied in airborne measurements, where it was found that majority of atmospheric ice particles have features that significantly change the way ice particles interact with solar light. The microscopic features make ice-containing clouds more reflective than previously thought, which could have consequences for predicting our climate.
Robert Jackson, Jeffrey R. French, David C. Leon, David M. Plummer, Sonia Lasher-Trapp, Alan M. Blyth, and Alexei Korolev
Atmos. Chem. Phys., 18, 15329–15344, https://doi.org/10.5194/acp-18-15329-2018, https://doi.org/10.5194/acp-18-15329-2018, 2018
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This paper looks at microphysical observations of growing cumulus clouds in the southwest United Kingdom sampled during the COnvective Precipitation Experiment (COPE). Our results suggest that secondary ice production processes are contributing to the observed concentrations and that entrainment of particles from remnant cloud layers may have acted to aid in secondary ice production.
Michael S. Diamond, Amie Dobracki, Steffen Freitag, Jennifer D. Small Griswold, Ashley Heikkila, Steven G. Howell, Mary E. Kacarab, James R. Podolske, Pablo E. Saide, and Robert Wood
Atmos. Chem. Phys., 18, 14623–14636, https://doi.org/10.5194/acp-18-14623-2018, https://doi.org/10.5194/acp-18-14623-2018, 2018
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Smoke from Africa can mix into clouds over the southeast Atlantic and create new droplets, which brightens the clouds, reflects more sunlight, and thus cools the region. Using aircraft data from a NASA field campaign, we find that cloud properties are correlated with smoke as expected when the smoke is below the clouds but not when smoke is above the clouds because it takes several days for clouds to mix smoke downward. We recommend methods that can track clouds as they move for future studies.
Matthew S. Norgren, Gijs de Boer, and Matthew D. Shupe
Atmos. Chem. Phys., 18, 13345–13361, https://doi.org/10.5194/acp-18-13345-2018, https://doi.org/10.5194/acp-18-13345-2018, 2018
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Arctic mixed-phase clouds are a critical component of the Arctic climate system because of their ability to influence the surface radiation budget. The radiative impact of an individual cloud is closely linked to the ability of the cloud to convert liquid drops to ice. In this paper, we show through an observational record that clouds present in polluted atmospheric conditions have lower amounts of ice than similar clouds found in clean conditions.
Nelli Narendra Reddy, Madineni Venkat Ratnam, Ghouse Basha, and Varaha Ravikiran
Atmos. Chem. Phys., 18, 11709–11727, https://doi.org/10.5194/acp-18-11709-2018, https://doi.org/10.5194/acp-18-11709-2018, 2018
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Cloud vertical structure affects large-scale atmosphere circulation by altering gradients in total diabatic heating and cooling and latent heat release. Detailed cloud vertical structure in all seasons, including diurnal variation over the Indian region, is made for the first time. The detected cloud layers are verified with independent observations using cloud particle sensor sonde. Heating and cooling in the troposphere and lower stratosphere due to these cloud layers are also investigated.
Aurélien Chauvigné, Olivier Jourdan, Alfons Schwarzenboeck, Christophe Gourbeyre, Jean François Gayet, Christiane Voigt, Hans Schlager, Stefan Kaufmann, Stephan Borrmann, Sergej Molleker, Andreas Minikin, Tina Jurkat, and Ulrich Schumann
Atmos. Chem. Phys., 18, 9803–9822, https://doi.org/10.5194/acp-18-9803-2018, https://doi.org/10.5194/acp-18-9803-2018, 2018
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This paper demonstrates a new form of statistical analysis of contrail to cirrus evolution. The authors show well-separated analyses of the different stages of the contrail's evolution, which allows us to study their optical, microphysical, and chemical properties. These results could be used to develop representative parameterizations of the scattering and geometrical properties of the ice crystals’ shapes and sizes, observed in the visible wavelength range.
Die Wang, Scott E. Giangrande, Mary Jane Bartholomew, Joseph Hardin, Zhe Feng, Ryan Thalman, and Luiz A. T. Machado
Atmos. Chem. Phys., 18, 9121–9145, https://doi.org/10.5194/acp-18-9121-2018, https://doi.org/10.5194/acp-18-9121-2018, 2018
Alexander Beck, Jan Henneberger, Jacob P. Fugal, Robert O. David, Larissa Lacher, and Ulrike Lohmann
Atmos. Chem. Phys., 18, 8909–8927, https://doi.org/10.5194/acp-18-8909-2018, https://doi.org/10.5194/acp-18-8909-2018, 2018
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This study assesses the impact of surface processes (e.g. blowing snow) on in situ cloud observations at Sonnblick Observatory. Vertical profiles of ice crystal number concentrations (ICNCs) above a snow-covered surface were observed up to a height of 10 m. The ICNC near the ground is at least a factor of 2 larger than at 10 m. Therefore, in situ measurements of ICNCs at mountain-top research stations close to the surface are strongly influenced by surface processes and overestimate the ICNC.
Ian Boutle, Jeremy Price, Innocent Kudzotsa, Harri Kokkola, and Sami Romakkaniemi
Atmos. Chem. Phys., 18, 7827–7840, https://doi.org/10.5194/acp-18-7827-2018, https://doi.org/10.5194/acp-18-7827-2018, 2018
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Aerosol processes are a key mechanism in the development of fog. Poor representation of aerosol–fog interaction can result in large biases in fog forecasts, such as surface temperatures which are too high and fog which is too deep and long lived. A relatively simple representation of aerosol–fog interaction can actually lead to significant improvements in forecasting. Aerosol–fog interaction can have a large effect on the climate system but is poorly represented in climate models.
Luiz A. T. Machado, Alan J. P. Calheiros, Thiago Biscaro, Scott Giangrande, Maria A. F. Silva Dias, Micael A. Cecchini, Rachel Albrecht, Meinrat O. Andreae, Wagner F. Araujo, Paulo Artaxo, Stephan Borrmann, Ramon Braga, Casey Burleyson, Cristiano W. Eichholz, Jiwen Fan, Zhe Feng, Gilberto F. Fisch, Michael P. Jensen, Scot T. Martin, Ulrich Pöschl, Christopher Pöhlker, Mira L. Pöhlker, Jean-François Ribaud, Daniel Rosenfeld, Jaci M. B. Saraiva, Courtney Schumacher, Ryan Thalman, David Walter, and Manfred Wendisch
Atmos. Chem. Phys., 18, 6461–6482, https://doi.org/10.5194/acp-18-6461-2018, https://doi.org/10.5194/acp-18-6461-2018, 2018
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This overview discuss the main precipitation processes and their sensitivities to environmental conditions in the Central Amazon Basin. It presents a review of the knowledge acquired about cloud processes and rainfall formation in Amazonas. In addition, this study provides a characterization of the seasonal variation and rainfall sensitivities to topography, surface cover, and aerosol concentration. Airplane measurements were evaluated to characterize and contrast cloud microphysical properties.
André Welti, Konrad Müller, Zoë L. Fleming, and Frank Stratmann
Atmos. Chem. Phys., 18, 5307–5320, https://doi.org/10.5194/acp-18-5307-2018, https://doi.org/10.5194/acp-18-5307-2018, 2018
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We report on ambient concentrations of ice nuclei, measured on the Cabo Verde islands. Concentrations are found to exponentially increase by 7 orders of magnitude from −5 to −38 °C. At each temperature, the frequency distribution of observed concentrations can be described by a lognormal distribution, typical for random dilution of substances during transport. Random dilution is found to account for larger fluctuations in IN concentration than seasonal changes and changes in air mass origin.
Norbert Kalthoff, Fabienne Lohou, Barbara Brooks, Gbenga Jegede, Bianca Adler, Karmen Babić, Cheikh Dione, Adewale Ajao, Leonard K. Amekudzi, Jeffrey N. A. Aryee, Muritala Ayoola, Geoffrey Bessardon, Sylvester K. Danuor, Jan Handwerker, Martin Kohler, Marie Lothon, Xabier Pedruzo-Bagazgoitia, Victoria Smith, Lukman Sunmonu, Andreas Wieser, Andreas H. Fink, and Peter Knippertz
Atmos. Chem. Phys., 18, 2913–2928, https://doi.org/10.5194/acp-18-2913-2018, https://doi.org/10.5194/acp-18-2913-2018, 2018
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Extended low-level stratus clouds (LLC) form frequently in southern West Africa during the night-time and persist long into the next day. They affect the radiation budget, atmospheric boundary-layer (BL) evolution and regional climate. The relevant processes governing their formation and dissolution are not fully understood. Thus, a field campaign was conducted in summer 2016, which provided a comprehensive data set for process studies, specifically of interactions between LLC and BL conditions.
Kathleen A. Schiro and J. David Neelin
Atmos. Chem. Phys., 18, 1997–2010, https://doi.org/10.5194/acp-18-1997-2018, https://doi.org/10.5194/acp-18-1997-2018, 2018
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Downdraft processes in climate models are poorly constrained, largely due to a lack of robust, statistical relationships describing them. Using multi-instrument data from the GoAmazon2014/5 campaign, downdraft properties of mesoscale-organized and unorganized systems are compared and such statistics are presented. Both vertical velocity retrievals and thermodynamic arguments are consistent in suggesting a spectrum of downdraft mass origin levels throughout the lowest few kilometers.
Micael A. Cecchini, Luiz A. T. Machado, Manfred Wendisch, Anja Costa, Martina Krämer, Meinrat O. Andreae, Armin Afchine, Rachel I. Albrecht, Paulo Artaxo, Stephan Borrmann, Daniel Fütterer, Thomas Klimach, Christoph Mahnke, Scot T. Martin, Andreas Minikin, Sergej Molleker, Lianet H. Pardo, Christopher Pöhlker, Mira L. Pöhlker, Ulrich Pöschl, Daniel Rosenfeld, and Bernadett Weinzierl
Atmos. Chem. Phys., 17, 14727–14746, https://doi.org/10.5194/acp-17-14727-2017, https://doi.org/10.5194/acp-17-14727-2017, 2017
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This study introduces and explores the concept of gamma phase space. This space is able to represent all possible variations in the cloud droplet size distributions (DSDs). The methodology was applied to recent in situ aircraft measurements over the Amazon. It is shown that the phase space is able to represent several processes occurring in the clouds in a simple manner. The consequences for cloud studies, modeling, and the representation of the transition from warm to mixed phase are discussed.
Cited articles
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Barth, M., Cantrell, C., Brune, W., and Rutledge, S.: Scientific Program Overview (SPO) for a Deep Convective Clouds and Chemistry (DC3) Field Campaign, available at: http://www2.acd.ucar.edu/sites/default/files/dc3/DC3_SciencePlan-w.pdf (last access: 18 February 2014), 2012.
Connolly, P. J., Saunders, C. P. R., Gallagher, M. W., Bower, K. N., Flynn, M. J., Choularton, T. W., Whiteway, J., and Lawson, R. P.: Aircraft observations of the influence of electric fields on the aggregation of ice crystals, Q. J. Roy. Meteor. Soc., 131, 1695–1712, https://doi.org/10.1256/qj.03.217, 2005.
Cotton, R. J., Field, P. R., Ulanowski, Z., Kaye, P. H., Hirst, E., Greenaway, R. S., Crawford, I., Crosier, J., and Dorsey, J.: The effective density of small ice particles obtained from in situ aircraft observations of mid-latitude cirrus, Q. J. Roy. Meteor. Soc., 139, 1923–1934, https://doi.org/10.1002/qj.2058, 2013.
Davis, S. M., Hallar, A. G., Avallone, L. M., and Engblom, W.: Measurements of ice water content with a tunable diode laser hygrometer: Calibration procedure and inlet analysis, J. Atmos. Ocean. Tech., 24, 463–475, https://doi.org/10.1175/JTECH1975.1, 2007a.
Davis, S. M., Avallone, L. M, Weinstock, E. M, Twohy, C. H., Smith, J. B., and Kok, G. L.: Comparisons of in situ measurements of cirrus cloud ice water content, J. Geophys. Res., 112, D10212, https://doi.org/10.1029/2006JD008214, 2007b.
Dorsi, S. W., Kalnajs, L. E., Toohey, D. W., and Avallone, L. M.: A fiber-coupled laser hygrometer for airborne total water measurement, Atmos. Meas. Tech. Discuss., 6, 7355–7378, https://doi.org/10.5194/amtd-6-7355-2013, 2013.
Field, P. R., Heymsfield, A. J., and Bansemer, A.: Shattering and Particle Interarrival Times Measured by Optical Array Probes in Ice Clouds, J. Atmos. Ocean. Tech., 23, 1357–1371, 2006.
Gallagher, M. W., Connolly, P. J., Crawford, I., Heymsfield, A., Bower, K. N., Choularton, T. W., Allen, G., Flynn, M. J., Vaughan, G., and Hacker, J.: Observations and modelling of microphysical variability, aggregation and sedimentation in tropical anvil cirrus outflow regions, Atmos. Chem. Phys., 12, 6609–6628, https://doi.org/10.5194/acp-12-6609-2012, 2012.
Gardiner, B. A and Hallett, J.: Degradation of in-cloud forward scattering spectrometer probe measurements in the presence of ice particles, J. Atmos. Ocean. Tech., 2, 171–180, 1985.
Gayet, J.-F., Mioche, G., Bugliaro, L., Protat, A., Minikin, A., Wirth, M., Dörnbrack, A., Shcherbakov, V., Mayer, B., Garnier, A., and Gourbeyre, C.: On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment, Atmos. Chem. Phys., 12, 727–744, https://doi.org/10.5194/acp-12-727-2012, 2012.
Heymsfield, A. J., Bansemer, A., Heymsfield, G., and Fierro, A. O.: Microphysics of Maritime Tropical Convective Updrafts at Temperatures from −20° to −60°, J. Atmos. Sci., 66, 3530–3562, https://doi.org/10.1175/2009JAS3107.1, 2009.
Jensen, E. J., Lawson, P., Baker, B., Pilson, B., Mo, Q., Heymsfield, A. J., Bansemer, A., Bui, T. P., McGill, M., Hlavka, D., Heymsfield, G., Platnick, S., Arnold, G. T., and Tanelli, S.: On the importance of small ice crystals in tropical anvil cirrus, Atmos. Chem. Phys., 9, 5519–5537, https://doi.org/10.5194/acp-9-5519-2009, 2009.
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