Articles | Volume 23, issue 8
https://doi.org/10.5194/acp-23-4775-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-23-4775-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
24 Apr 2023
Research article |
| 24 Apr 2023
| 24 Apr 2023
An attribution of the low single-scattering albedo of biomass burning aerosol over the southeastern Atlantic
Amie Dobracki
CORRESPONDING AUTHOR
Department of Atmospheric Sciences, Rosenstiel School, University of Miami, Miami, Florida, USA
Department of Atmospheric Sciences, Rosenstiel School, University of Miami, Miami, Florida, USA
Steven G. Howell
Department of Oceanography, University of Hawai`i at Mānoa, Honolulu, Hawaii, USA
Pablo Saide
Department of Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, California, USA
Steffen Freitag
Department of Oceanography, University of Hawai`i at Mānoa, Honolulu, Hawaii, USA
Allison C. Aiken
Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
Sharon P. Burton
NASA Langley Research Center, Hampton, VA, USA
Arthur J. Sedlacek III
Brookhaven National Laboratory, Upton, New York, USA
Jens Redemann
School of Meteorology, University of Oklahoma, Norman, Oklahoma, USA
Robert Wood
Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
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Sarah J. Doherty, Pablo E. Saide, Paquita Zuidema, Yohei Shinozuka, Gonzalo A. Ferrada, Hamish Gordon, Marc Mallet, Kerry Meyer, David Painemal, Steven G. Howell, Steffen Freitag, Amie Dobracki, James R. Podolske, Sharon P. Burton, Richard A. Ferrare, Calvin Howes, Pierre Nabat, Gregory R. Carmichael, Arlindo da Silva, Kristina Pistone, Ian Chang, Lan Gao, Robert Wood, and Jens Redemann
Atmos. Chem. Phys., 22, 1–46, https://doi.org/10.5194/acp-22-1-2022, https://doi.org/10.5194/acp-22-1-2022, 2022
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Julianna A. Christopoulos, Pablo E. Saide, Manas R. Mohanty, Nattamon Maneenoi, Jhoon Kim, Laura Judd, Katherine R. Travis, Savitri Garivait, Agapol Junpen, Kazuyuki Miyazaki, Jinkyul Choi, Takashi Sekiya, David Peterson, Theodore M. McHardy, Nicholas Gapp, Jason M. St. Clair, Erin Delaria, Glenn M. Wolfe, Abby Sebol, Alessandro Franchin, Changmin Cho, Morgan L. Silverman, and James H. Crawford
Atmos. Chem. Phys., 26, 8021–8050, https://doi.org/10.5194/acp-26-8021-2026, https://doi.org/10.5194/acp-26-8021-2026, 2026
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Lucas A. McMichael, Ehsan Erfani, Robert Wood, and Knut von Salzen
EGUsphere, https://doi.org/10.5194/egusphere-2026-2730, https://doi.org/10.5194/egusphere-2026-2730, 2026
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This study explores how aerosol plumes spread in marine clouds and how that affects cloud brightening. Changes in turbulence strongly affect plume spreading rates, but have little effect on the overall brightening in the cases studied. The main uncertainties are aerosol lifetime and how clouds adjust to the aerosols. Climate models often assume that plumes spread instantly, and we find that this may overestimate cooling in some cases.
Jonas Witthuhn, Hartwig Deneke, Andreas Macke, Oscar Ritter, Jens Redemann, Connor J. Flynn, Abdulamid A. Fakoya, Bradley F. Lamkin, Emily D. Lenhardt, Logan T. Mitchell, Emily K. West, David M. Romps, Rusen Öktem, and Heike Kalesse-Los
Atmos. Chem. Phys., 26, 5727–5745, https://doi.org/10.5194/acp-26-5727-2026, https://doi.org/10.5194/acp-26-5727-2026, 2026
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Haruki Hirasawa, Matthew Henry, Philip J. Rasch, Robert Wood, Sarah J. Doherty, James Haywood, Alex Wong, Jean-Francois Lamarque, Ezra Brody, and Hailong Wang
Geosci. Model Dev., 19, 3257–3283, https://doi.org/10.5194/gmd-19-3257-2026, https://doi.org/10.5194/gmd-19-3257-2026, 2026
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Logan T. Mitchell, Connor J. Flynn, Kristina Pistone, Samuel E. LeBlanc, K. Sebastian Schmidt, Hong Chen, Paquita Zuidema, Robert Wood, and Jens Redemann
EGUsphere, https://doi.org/10.5194/egusphere-2026-1418, https://doi.org/10.5194/egusphere-2026-1418, 2026
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During 2016–2018, NASA conducted an airborne field campaign over the Southeast Atlantic Ocean to study biomass burning aerosols emitted from Southern African fires. We have found that aerosol scattering increases over the course of the emission season, which is due to a compositional change within black carbon as the source fires shift southeastward, rather than an increase in brown carbon. This aerosol brightening is also noted within a 30-year aerosol climatology from ground-based stations.
John J. D'Alessandro, Robert Wood, and Peter N. Blossey
Atmos. Chem. Phys., 26, 4067–4088, https://doi.org/10.5194/acp-26-4067-2026, https://doi.org/10.5194/acp-26-4067-2026, 2026
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Many theories speculate drop clustering is an important facet of precipitation initiation. This study evaluates the relationship between drop size and drop clustering surrounding the individual drops. Large drops are generally isolated from neighboring drops, particularly in subsaturated environments. Samples capturing this trend also have the broadest drop size distributions and largest drops, suggesting the importance of entrainment-mixing to precipitation initiation.
Richard Ferrare, Johnathan Hair, Taylor Shingler, Chris Hostetler, Amin Nehrir, Marta Fenn, Amy Jo Scarino, Sharon Burton, Marian Clayton, James Collins, Laura Judd, James Crawford, Katherine Travis, Travis Toth, Pablo Saide, Jose Luis Jimenez, Pedro Campuzano-Jost, Guy Symonds, Richard Moore, Luke Ziemba, Michael Shook, Glenn Diskin, Joshua P. DiGangi, Ryan Bennett, Chia-Hsiang Ho, Lim-Seok Chang, Adisak Aiampisanuvong, and Ittipol Pawarmart
Atmos. Meas. Tech., 18, 7735–7766, https://doi.org/10.5194/amt-18-7735-2025, https://doi.org/10.5194/amt-18-7735-2025, 2025
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Jeffrey S. Reid, Robert E. Holz, Chris A. Hostetler, Richard A. Ferrare, Juli I. Rubin, Elizabeth J. Thompson, Susan C. van den Heever, Corey G. Amiot, Sharon P. Burton, Joshua P. DiGangi, Glenn S. Diskin, Joshua H. Cossuth, Daniel P. Eleuterio, Edwin W. Eloranta, Ralph Kuehn, Willem J. Marais, Hal B. Maring, Armin Sorooshian, Kenneth L. Thornhill, Charles R. Trepte, Jian Wang, Peng Xian, and Luke D. Ziemba
Atmos. Chem. Phys., 25, 18639–18673, https://doi.org/10.5194/acp-25-18639-2025, https://doi.org/10.5194/acp-25-18639-2025, 2025
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We document air and ship born measurements of the vertical distribution of pollution and biomass burning aerosol particles transported within the Maritime Continent's monsoonal flows for 1000s of kilometers, and yet still exhibit intricate patterns around clouds near the ocean's surface. Findings demonstrate that, while aerosol transport occurs near the surface, there is heterogeneity in particle extinction that must be considered for both in situ observations and satellite retrievals.
Isabel L. McCoy, Sunil Baidar, Paquita Zuidema, Jan Kazil, W. Alan Brewer, Wayne M. Angevine, and Graham Feingold
Atmos. Chem. Phys., 25, 16233–16261, https://doi.org/10.5194/acp-25-16233-2025, https://doi.org/10.5194/acp-25-16233-2025, 2025
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We use ship observations to investigate the dynamics of small clouds over the tropical oceans. When these cumulus clouds cluster together, they more efficiently move moisture into the cloud layer due to strengthened updrafts. This encourages further clustering, increases local cloud development success, and may help sustain clouds against diurnal variations in their environment. These results have implications for cumulus feedback on the climate, a significant uncertainty in future projections.
Meloë S. F. Kacenelenbogen, Ralph Kuehn, Nandana D. Amarasinghe, Kerry G. Meyer, Edward P. Nowottnick, Mark A. Vaughan, Hong Chen, Sebastian Schmidt, Richard A. Ferrare, Johnathan W. Hair, Robert C. Levy, Hongbin Yu, Paquita Zuidema, Robert Holz, and Willem Marais
Atmos. Chem. Phys., 25, 15875–15911, https://doi.org/10.5194/acp-25-15875-2025, https://doi.org/10.5194/acp-25-15875-2025, 2025
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Aerosols perturb the radiation balance of the Earth–atmosphere system. To reduce the uncertainty in quantifying present-day climate change, we combine two satellite sensors and a model to assess the aerosol effects on radiation in all-sky conditions. Satellite-based and coincident aircraft measurements of aerosol radiative effects agree well over the southeast Atlantic. This constitutes a crucial first evaluation before we apply our method to more years and more regions of the world.
Sharon P. Burton, Johnathan W. Hair, Chris A. Hostetler, Marta A. Fenn, John A. Smith, and Richard A. Ferrare
Atmos. Meas. Tech., 18, 6527–6543, https://doi.org/10.5194/amt-18-6527-2025, https://doi.org/10.5194/amt-18-6527-2025, 2025
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Advanced lidars can retrieve atmospheric aerosol backscatter, extinction, and linear depolarization ratio. However excessive noise propagation in the traditional inversion method can make extinction unusable when the signal is weak, such as from space. Implementing a weak constraint can reduce the noise propagation while preserving accuracy. Here we also focus on fully characterizing both random and systematic uncertainties and examining the tradeoff between uncertainty and resolution.
Eric Giuffrida, Kate Johnson, Tyler Tatro, Paquita Zuidema, and Hamish Gordon
Atmos. Chem. Phys., 25, 14879–14907, https://doi.org/10.5194/acp-25-14879-2025, https://doi.org/10.5194/acp-25-14879-2025, 2025
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Smoke aerosols emitted from summer African fires periodically travel across the ocean and interact with one of Earth’s largest permanent cloud decks. Researchers quantify the heating and cooling effects of this interaction using climate models. However, the use of different historical weather matching methods has produced a large variation in results. Here, we test method variations commonly used today and conclude with new guidelines for achieving the most accurate results.
Emily Lenhardt, Lan Gao, Chris A. Hostetler, Richard A. Ferrare, Sharon P. Burton, Richard H. Moore, Luke D. Ziemba, Ewan Crosbie, Armin Sorooshian, Cassidy Soloff, and Jens Redemann
Atmos. Chem. Phys., 25, 13747–13768, https://doi.org/10.5194/acp-25-13747-2025, https://doi.org/10.5194/acp-25-13747-2025, 2025
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Small particles that form cloud droplets greatly impact Earth's climate but are very difficult to measure. If we can measure them using satellite-based instruments, we greatly increase the amount of available data on their concentrations. In this study, we find that including information about particle size is most important to measure them accurately from such satellite-based instruments. This can inform future studies on how to obtain more accurate information about small particles.
Logan T. Mitchell, Connor J. Flynn, Kristina Pistone, Samuel E. LeBlanc, K. Sebastian Schmidt, and Jens Redemann
Earth Syst. Sci. Data, 17, 5303–5313, https://doi.org/10.5194/essd-17-5303-2025, https://doi.org/10.5194/essd-17-5303-2025, 2025
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During 2016–2018, NASA conducted an airborne field campaign over the Southeast Atlantic Ocean to study biomass burning aerosols emitted from Southern African fires. These aerosols then interact with stratocumulus clouds over the Southeast Atlantic, which is difficult for climate models to account for. Our instrument, 4STAR, determines aerosol radiative properties. A dataset was already created for 2016, but additional quality control was required to address instrument issues for 2017 and 2018.
Haochi Che, Lu Zhang, Michal Segal-Rozenhaimer, Caroline Dang, Paquita Zuidema, and Arthur J. Sedlacek III
Atmos. Chem. Phys., 25, 10987–11002, https://doi.org/10.5194/acp-25-10987-2025, https://doi.org/10.5194/acp-25-10987-2025, 2025
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We studied aerosols over a remote island in the Atlantic Ocean to understand how they affect cloud formation. By analyzing data from two fire seasons, we found that changes in sea salt and smoke from fires strongly influenced how easily these particles form cloud droplets. In 2017, sea salt increased due to weather changes, making the particles more water-attracting. This helps us understand how natural and human activities impact clouds and climate.
Ehsan Erfani, Robert Wood, Peter Blossey, Sarah J. Doherty, and Ryan Eastman
Atmos. Chem. Phys., 25, 8743–8768, https://doi.org/10.5194/acp-25-8743-2025, https://doi.org/10.5194/acp-25-8743-2025, 2025
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In this study, we explore how marine clouds interact with aerosols. We introduce a novel approach to identify a reduced number of representative cases from a wide array of observed environmental conditions prevalent in the Northeast Pacific. We create over 2200 trajectories from observations and use cloud-resolving simulations to investigate how marine low clouds evolve in two different cases. It is shown that aerosols can delay cloud breakup, but their impact depends on precipitation.
Abdulamid A. Fakoya, Jens Redemann, Pablo E. Saide, Lan Gao, Logan T. Mitchell, Calvin Howes, Amie Dobracki, Ian Chang, Gonzalo A. Ferrada, Kristina Pistone, Samuel E. Leblanc, Michal Segal-Rozenhaimer, Arthur J. Sedlacek III, Thomas Eck, Brent Holben, Pawan Gupta, Elena Lind, Paquita Zuidema, Gregory Carmichael, and Connor J. Flynn
Atmos. Chem. Phys., 25, 7879–7902, https://doi.org/10.5194/acp-25-7879-2025, https://doi.org/10.5194/acp-25-7879-2025, 2025
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Tiny atmospheric particles from wildfire smoke impact the climate by interacting with sunlight and clouds, the extent of which is uncertain due to gaps in understanding how smoke changes over time. We developed a new method using remote sensing instruments to track how these particles evolve during atmospheric transport. Our results show that the ability of these particles to absorb sunlight increases as they travel. This discovery could help improve predictions of future climate scenarios.
Qingqing He, Jingru Cao, Pablo E. Saide, Tong Ye, Weihang Wang, Ming Zhang, and Jiejun Huang
Atmos. Chem. Phys., 25, 6663–6677, https://doi.org/10.5194/acp-25-6663-2025, https://doi.org/10.5194/acp-25-6663-2025, 2025
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We analyzed ground-level ozone variations and exposure hotspots across China (2000–2020) at multiple scales using daily 1 km ozone data derived from satellite-sourced land-surface temperature data via a machine-learning hindcasting model. The dataset was validated using cross-validation and external measurements. A non-monotonic trend with regional and seasonal variations emerged, with turning points around 2008 and 2015. Ozone levels >100 μg m‾³ shifted from June to May, while levels >160 μg m‾³ expanded in the North China Plain.
Cynthia H. Whaley, Tim Butler, Jose A. Adame, Rupal Ambulkar, Steve R. Arnold, Rebecca R. Buchholz, Benjamin Gaubert, Douglas S. Hamilton, Min Huang, Hayley Hung, Johannes W. Kaiser, Jacek W. Kaminski, Christoph Knote, Gerbrand Koren, Jean-Luc Kouassi, Meiyun Lin, Tianjia Liu, Jianmin Ma, Kasemsan Manomaiphiboon, Elisa Bergas Masso, Jessica L. McCarty, Mariano Mertens, Mark Parrington, Helene Peiro, Pallavi Saxena, Saurabh Sonwani, Vanisa Surapipith, Damaris Y. T. Tan, Wenfu Tang, Veerachai Tanpipat, Kostas Tsigaridis, Christine Wiedinmyer, Oliver Wild, Yuanyu Xie, and Paquita Zuidema
Geosci. Model Dev., 18, 3265–3309, https://doi.org/10.5194/gmd-18-3265-2025, https://doi.org/10.5194/gmd-18-3265-2025, 2025
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The multi-model experiment design of the HTAP3 Fires project takes a multi-pollutant approach to improving our understanding of transboundary transport of wildland fire and agricultural burning emissions and their impacts. The experiments are designed with the goal of answering science policy questions related to fires. The options for the multi-model approach, including inputs, outputs, and model setup, are discussed, and the official recommendations for the project are presented.
Je-Yun Chun, Robert Wood, Peter N. Blossey, and Sarah J. Doherty
Atmos. Chem. Phys., 25, 5251–5271, https://doi.org/10.5194/acp-25-5251-2025, https://doi.org/10.5194/acp-25-5251-2025, 2025
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This study explores how aerosols affect clouds transitioning from stratocumulus to cumulus along trade winds under varying atmospheric conditions. We found that aerosols typically reduce precipitation and raise cloud height, but their impact changes when subsidence changes by aerosol enhancement are considered. Our findings indicate that the cooling effect of aerosols might be overestimated if these atmospheric changes are not accounted for.
Florian Tornow, Ann Fridlind, George Tselioudis, Brian Cairns, Andrew Ackerman, Seethala Chellappan, David Painemal, Paquita Zuidema, Christiane Voigt, Simon Kirschler, and Armin Sorooshian
Atmos. Chem. Phys., 25, 5053–5074, https://doi.org/10.5194/acp-25-5053-2025, https://doi.org/10.5194/acp-25-5053-2025, 2025
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The recent NASA campaign ACTIVATE (Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment) performed 71 tandem flights in mid-latitude marine cold-air outbreaks off the US eastern seaboard. We provide meteorological and cloud transition stage context, allowing us to identify days that are most suitable for Lagrangian modeling and analysis. Surveyed cloud properties show signatures of cloud microphysical processes, such as cloud-top entrainment and secondary ice formation.
Chris J. Wright, Joel A. Thornton, Lyatt Jaeglé, Yang Cao, Yannian Zhu, Jihu Liu, Randall Jones II, Robert Holzworth, Daniel Rosenfeld, Robert Wood, Peter Blossey, and Daehyun Kim
Atmos. Chem. Phys., 25, 2937–2946, https://doi.org/10.5194/acp-25-2937-2025, https://doi.org/10.5194/acp-25-2937-2025, 2025
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Aerosol particles influence clouds, which exert a large forcing on solar radiation and freshwater. To better understand the mechanisms by which aerosol influences thunderstorms, we look at the two busiest shipping lanes in the world, where recent regulations have reduced sulfur emissions by nearly an order of magnitude. We find that the reduction in emissions has been accompanied by a dramatic decrease in both lightning and the number of droplets in clouds over the shipping lanes.
Kira Zeider, Kayla McCauley, Sanja Dmitrovic, Leong Wai Siu, Yonghoon Choi, Ewan C. Crosbie, Joshua P. DiGangi, Glenn S. Diskin, Simon Kirschler, John B. Nowak, Michael A. Shook, Kenneth L. Thornhill, Christiane Voigt, Edward L. Winstead, Luke D. Ziemba, Paquita Zuidema, and Armin Sorooshian
Atmos. Chem. Phys., 25, 2407–2422, https://doi.org/10.5194/acp-25-2407-2025, https://doi.org/10.5194/acp-25-2407-2025, 2025
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In situ aircraft data collected over the northwest Atlantic Ocean are utilized to compare aerosol conditions and turbulence between near-surface and below-cloud-base altitudes for different regimes of coupling strength between those two levels, along with how cloud microphysical properties vary across those regimes. Stronger coupling yields more homogenous aerosol structure vertically along with higher cloud drop concentrations and sea salt influence in clouds.
Amie Dobracki, Ernie R. Lewis, Arthur J. Sedlacek III, Tyler Tatro, Maria A. Zawadowicz, and Paquita Zuidema
Atmos. Chem. Phys., 25, 2333–2363, https://doi.org/10.5194/acp-25-2333-2025, https://doi.org/10.5194/acp-25-2333-2025, 2025
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Biomass-burning aerosol is commonly present in the marine boundary layer over the southeast Atlantic Ocean between June and October. Our research indicates that burning conditions, aerosol transport pathways, and prolonged oxidation processes (heterogeneous and aqueous phases) determine the chemical, microphysical, and optical properties of the boundary layer aerosol. Notably, we find that the aerosol optical properties can be estimated from the chemical properties alone.
Lu Zhang, Michal Segal-Rozenhaimer, Haochi Che, Caroline Dang, Junying Sun, Ye Kuang, Paola Formenti, and Steven G. Howell
Atmos. Chem. Phys., 24, 13849–13864, https://doi.org/10.5194/acp-24-13849-2024, https://doi.org/10.5194/acp-24-13849-2024, 2024
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Using airborne measurements over the southeast Atlantic Ocean, we examined how much moisture aerosols take up during Africa’s biomass burning season. Our study revealed the important role of organic aerosols and introduced a predictive model for moisture uptake, accounting for organics, sulfate, and black carbon, summarizing results from various campaigns. These findings improve our understanding of aerosol–moisture interactions and their radiative effects in this climatically critical region.
Jerome D. Fast, Adam C. Varble, Fan Mei, Mikhail Pekour, Jason Tomlinson, Alla Zelenyuk, Art J. Sedlacek III, Maria Zawadowicz, and Louisa Emmons
Atmos. Chem. Phys., 24, 13477–13502, https://doi.org/10.5194/acp-24-13477-2024, https://doi.org/10.5194/acp-24-13477-2024, 2024
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Aerosol property measurements recently collected on the ground and by a research aircraft in central Argentina during the Cloud, Aerosol, and Complex Terrain Interactions (CACTI) campaign exhibit large spatial and temporal variability. These measurements coupled with coincident meteorological information provide a valuable data set needed to evaluate and improve model predictions of aerosols in a traditionally data-sparse region of South America.
Philip J. Rasch, Haruki Hirasawa, Mingxuan Wu, Sarah J. Doherty, Robert Wood, Hailong Wang, Andy Jones, James Haywood, and Hansi Singh
Geosci. Model Dev., 17, 7963–7994, https://doi.org/10.5194/gmd-17-7963-2024, https://doi.org/10.5194/gmd-17-7963-2024, 2024
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We introduce a protocol to compare computer climate simulations to better understand a proposed strategy intended to counter warming and climate impacts from greenhouse gas increases. This slightly changes clouds in six ocean regions to reflect more sunlight and cool the Earth. Example changes in clouds and climate are shown for three climate models. Cloud changes differ between the models, but precipitation and surface temperature changes are similar when their cooling effects are made similar.
Lucas A. McMichael, Michael J. Schmidt, Robert Wood, Peter N. Blossey, and Lekha Patel
Geosci. Model Dev., 17, 7867–7888, https://doi.org/10.5194/gmd-17-7867-2024, https://doi.org/10.5194/gmd-17-7867-2024, 2024
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Marine cloud brightening (MCB) is a climate intervention technique to potentially cool the climate. Climate models used to gauge regional climate impacts associated with MCB often assume large areas of the ocean are uniformly perturbed. However, a more realistic representation of MCB application would require information about how an injected particle plume spreads. This work aims to develop such a plume-spreading model.
Kristina Pistone, Eric M. Wilcox, Paquita Zuidema, Marco Giordano, James Podolske, Samuel E. LeBlanc, Meloë Kacenelenbogen, Steven G. Howell, and Steffen Freitag
Atmos. Chem. Phys., 24, 7983–8005, https://doi.org/10.5194/acp-24-7983-2024, https://doi.org/10.5194/acp-24-7983-2024, 2024
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The springtime southeast Atlantic atmosphere contains lots of smoke from continental fires. This smoke travels with water vapor; more smoke means more humidity. We use aircraft observations and models to describe how the values change through the season and over the region. We sort the atmosphere into different types by vertical structure and amount of smoke and humidity. Since our work shows how frequently these components coincide, it helps to better quantify heating effects over this region.
Ryan Eastman, Isabel L. McCoy, Hauke Schulz, and Robert Wood
Atmos. Chem. Phys., 24, 6613–6634, https://doi.org/10.5194/acp-24-6613-2024, https://doi.org/10.5194/acp-24-6613-2024, 2024
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Cloud types are determined using machine learning image classifiers applied to satellite imagery for 1 year in the North Atlantic. This survey of these cloud types shows that the climate impact of a cloud scene is, in part, a function of cloud type. Each type displays a different mix of thick and thin cloud cover, with the fraction of thin cloud cover having the strongest impact on the clouds' radiative effect. Future studies must account for differing properties and processes among cloud types.
Hiren T. Jethva, Omar Torres, Richard A. Ferrare, Sharon P. Burton, Anthony L. Cook, David B. Harper, Chris A. Hostetler, Jens Redemann, Vinay Kayetha, Samuel LeBlanc, Kristina Pistone, Logan Mitchell, and Connor J. Flynn
Atmos. Meas. Tech., 17, 2335–2366, https://doi.org/10.5194/amt-17-2335-2024, https://doi.org/10.5194/amt-17-2335-2024, 2024
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We introduce a novel synergy algorithm applied to ORALCES airborne measurements of above-cloud aerosol optical depth and UV–Vis satellite observations from OMI and MODIS to retrieve spectral aerosol single-scattering albedo of lofted layers of carbonaceous smoke aerosols over clouds. The development of the proposed aerosol–cloud algorithm implies a possible synergy of CALIOP and OMI–MODIS passive sensors to deduce a global product of AOD and SSA of absorbing aerosols above clouds.
Ryan N. Farley, James E. Lee, Laura-Hélèna Rivellini, Alex K. Y. Lee, Rachael Dal Porto, Christopher D. Cappa, Kyle Gorkowski, Abu Sayeed Md Shawon, Katherine B. Benedict, Allison C. Aiken, Manvendra K. Dubey, and Qi Zhang
Atmos. Chem. Phys., 24, 3953–3971, https://doi.org/10.5194/acp-24-3953-2024, https://doi.org/10.5194/acp-24-3953-2024, 2024
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The black carbon aerosol composition and mixing state were characterized using a soot particle aerosol mass spectrometer. Single-particle measurements revealed the major role of atmospheric processing in modulating the black carbon mixing state. A significant fraction of soot particles were internally mixed with oxidized organic aerosol and sulfate, with implications for activation as cloud nuclei.
Calvin Howes, Pablo E. Saide, Hugh Coe, Amie Dobracki, Steffen Freitag, Jim M. Haywood, Steven G. Howell, Siddhant Gupta, Janek Uin, Mary Kacarab, Chongai Kuang, L. Ruby Leung, Athanasios Nenes, Greg M. McFarquhar, James Podolske, Jens Redemann, Arthur J. Sedlacek, Kenneth L. Thornhill, Jenny P. S. Wong, Robert Wood, Huihui Wu, Yang Zhang, Jianhao Zhang, and Paquita Zuidema
Atmos. Chem. Phys., 23, 13911–13940, https://doi.org/10.5194/acp-23-13911-2023, https://doi.org/10.5194/acp-23-13911-2023, 2023
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To better understand smoke properties and its interactions with clouds, we compare the WRF-CAM5 model with observations from ORACLES, CLARIFY, and LASIC field campaigns in the southeastern Atlantic in August 2017. The model transports and mixes smoke well but does not fully capture some important processes. These include smoke chemical and physical aging over 4–12 days, smoke removal by rain, sulfate particle formation, aerosol activation into cloud droplets, and boundary layer turbulence.
Armin Sorooshian, Mikhail D. Alexandrov, Adam D. Bell, Ryan Bennett, Grace Betito, Sharon P. Burton, Megan E. Buzanowicz, Brian Cairns, Eduard V. Chemyakin, Gao Chen, Yonghoon Choi, Brian L. Collister, Anthony L. Cook, Andrea F. Corral, Ewan C. Crosbie, Bastiaan van Diedenhoven, Joshua P. DiGangi, Glenn S. Diskin, Sanja Dmitrovic, Eva-Lou Edwards, Marta A. Fenn, Richard A. Ferrare, David van Gilst, Johnathan W. Hair, David B. Harper, Miguel Ricardo A. Hilario, Chris A. Hostetler, Nathan Jester, Michael Jones, Simon Kirschler, Mary M. Kleb, John M. Kusterer, Sean Leavor, Joseph W. Lee, Hongyu Liu, Kayla McCauley, Richard H. Moore, Joseph Nied, Anthony Notari, John B. Nowak, David Painemal, Kasey E. Phillips, Claire E. Robinson, Amy Jo Scarino, Joseph S. Schlosser, Shane T. Seaman, Chellappan Seethala, Taylor J. Shingler, Michael A. Shook, Kenneth A. Sinclair, William L. Smith Jr., Douglas A. Spangenberg, Snorre A. Stamnes, Kenneth L. Thornhill, Christiane Voigt, Holger Vömel, Andrzej P. Wasilewski, Hailong Wang, Edward L. Winstead, Kira Zeider, Xubin Zeng, Bo Zhang, Luke D. Ziemba, and Paquita Zuidema
Earth Syst. Sci. Data, 15, 3419–3472, https://doi.org/10.5194/essd-15-3419-2023, https://doi.org/10.5194/essd-15-3419-2023, 2023
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The NASA Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) produced a unique dataset for research into aerosol–cloud–meteorology interactions. HU-25 Falcon and King Air aircraft conducted systematic and spatially coordinated flights over the northwest Atlantic Ocean. This paper describes the ACTIVATE flight strategy, instrument and complementary dataset products, data access and usage details, and data application notes.
Emily D. Lenhardt, Lan Gao, Jens Redemann, Feng Xu, Sharon P. Burton, Brian Cairns, Ian Chang, Richard A. Ferrare, Chris A. Hostetler, Pablo E. Saide, Calvin Howes, Yohei Shinozuka, Snorre Stamnes, Mary Kacarab, Amie Dobracki, Jenny Wong, Steffen Freitag, and Athanasios Nenes
Atmos. Meas. Tech., 16, 2037–2054, https://doi.org/10.5194/amt-16-2037-2023, https://doi.org/10.5194/amt-16-2037-2023, 2023
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Small atmospheric particles, such as smoke from wildfires or pollutants from human activities, impact cloud properties, and clouds have a strong influence on climate. To better understand the distributions of these particles, we develop relationships to derive their concentrations from remote sensing measurements from an instrument called a lidar. Our method is reliable for smoke particles, and similar steps can be taken to develop relationships for other particle types.
Ian Chang, Lan Gao, Connor J. Flynn, Yohei Shinozuka, Sarah J. Doherty, Michael S. Diamond, Karla M. Longo, Gonzalo A. Ferrada, Gregory R. Carmichael, Patricia Castellanos, Arlindo M. da Silva, Pablo E. Saide, Calvin Howes, Zhixin Xue, Marc Mallet, Ravi Govindaraju, Qiaoqiao Wang, Yafang Cheng, Yan Feng, Sharon P. Burton, Richard A. Ferrare, Samuel E. LeBlanc, Meloë S. Kacenelenbogen, Kristina Pistone, Michal Segal-Rozenhaimer, Kerry G. Meyer, Ju-Mee Ryoo, Leonhard Pfister, Adeyemi A. Adebiyi, Robert Wood, Paquita Zuidema, Sundar A. Christopher, and Jens Redemann
Atmos. Chem. Phys., 23, 4283–4309, https://doi.org/10.5194/acp-23-4283-2023, https://doi.org/10.5194/acp-23-4283-2023, 2023
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Abundant aerosols are present above low-level liquid clouds over the southeastern Atlantic during late austral spring. The model simulation differences in the proportion of aerosol residing in the planetary boundary layer and in the free troposphere can greatly affect the regional aerosol radiative effects. This study examines the aerosol loading and fractional aerosol loading in the free troposphere among various models and evaluates them against measurements from the NASA ORACLES campaign.
Francesca Gallo, Janek Uin, Kevin J. Sanchez, Richard H. Moore, Jian Wang, Robert Wood, Fan Mei, Connor Flynn, Stephen Springston, Eduardo B. Azevedo, Chongai Kuang, and Allison C. Aiken
Atmos. Chem. Phys., 23, 4221–4246, https://doi.org/10.5194/acp-23-4221-2023, https://doi.org/10.5194/acp-23-4221-2023, 2023
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This study provides a summary statistic of multiday aerosol plume transport event influences on aerosol physical properties and the cloud condensation nuclei budget at the U.S. Department of Energy Atmospheric Radiation Measurement Facility in the eastern North Atlantic (ENA). An algorithm that integrates aerosol properties is developed and applied to identify multiday aerosol transport events. The influence of the aerosol plumes on aerosol populations at the ENA is successively assessed.
Kai Krause, Folkard Wittrock, Andreas Richter, Dieter Busch, Anton Bergen, John P. Burrows, Steffen Freitag, and Olesia Halbherr
Atmos. Meas. Tech., 16, 1767–1787, https://doi.org/10.5194/amt-16-1767-2023, https://doi.org/10.5194/amt-16-1767-2023, 2023
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Inland shipping is an important source of nitrogen oxides (NOx). The amount of emitted NOx depends on the characteristics of the individual vessels and the traffic density. Ship emissions are often characterised by the amount of emitted NOx per unit of burnt fuel, and further knowledge about fuel consumption is needed to quantify the total emissions caused by ship traffic. In this study, a new approach to derive absolute emission rates (in g s−1) from onshore measurements is presented.
Zhenquan Wang, Jian Yuan, Robert Wood, Yifan Chen, and Tiancheng Tong
Atmos. Chem. Phys., 23, 3247–3266, https://doi.org/10.5194/acp-23-3247-2023, https://doi.org/10.5194/acp-23-3247-2023, 2023
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This study develops a novel profile-based algorithm based on the ERA5 to estimate the inversion strength in the planetary boundary layer better than the previous inversion index, which is a key low-cloud-controlling factor. This improved measure is more effective at representing the meteorological influence on low-cloud variations. It can better constrain the meteorological influence on low clouds to better isolate cloud responses to aerosols or to estimate low cloud feedbacks in climate models.
Je-Yun Chun, Robert Wood, Peter Blossey, and Sarah J. Doherty
Atmos. Chem. Phys., 23, 1345–1368, https://doi.org/10.5194/acp-23-1345-2023, https://doi.org/10.5194/acp-23-1345-2023, 2023
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We investigate the impact of injected aerosol on subtropical low marine clouds under a variety of meteorological conditions using high-resolution model simulations. This study illustrates processes perturbed by aerosol injections and their impact on cloud properties (e.g., cloud number concentration, thickness, and cover). We show that those responses are highly sensitive to background meteorological conditions, such as precipitation, and background cloud properties.
Haley M. Royer, Mira L. Pöhlker, Ovid Krüger, Edmund Blades, Peter Sealy, Nurun Nahar Lata, Zezhen Cheng, Swarup China, Andrew P. Ault, Patricia K. Quinn, Paquita Zuidema, Christopher Pöhlker, Ulrich Pöschl, Meinrat Andreae, and Cassandra J. Gaston
Atmos. Chem. Phys., 23, 981–998, https://doi.org/10.5194/acp-23-981-2023, https://doi.org/10.5194/acp-23-981-2023, 2023
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This paper presents atmospheric particle chemical composition and measurements of aerosol water uptake properties collected at Ragged Point, Barbados, during the winter of 2020. The result of this study indicates the importance of small African smoke particles for cloud droplet formation in the tropical North Atlantic and highlights the large spatial and temporal pervasiveness of smoke over the Atlantic Ocean.
Allison B. Marquardt Collow, Virginie Buchard, Peter R. Colarco, Arlindo M. da Silva, Ravi Govindaraju, Edward P. Nowottnick, Sharon Burton, Richard Ferrare, Chris Hostetler, and Luke Ziemba
Atmos. Chem. Phys., 22, 16091–16109, https://doi.org/10.5194/acp-22-16091-2022, https://doi.org/10.5194/acp-22-16091-2022, 2022
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Biomass burning aerosol impacts aspects of the atmosphere and Earth system through radiative forcing, serving as cloud condensation nuclei, and air quality. Despite its importance, the representation of biomass burning aerosol is not always accurate in models. Field campaign observations from CAMP2Ex are used to evaluate the mass and extinction of aerosols in the GEOS model. Notable biases in the model illuminate areas of future development with GEOS and the underlying GOCART aerosol module.
Ju-Mee Ryoo, Leonhard Pfister, Rei Ueyama, Paquita Zuidema, Robert Wood, Ian Chang, and Jens Redemann
Atmos. Chem. Phys., 22, 14209–14241, https://doi.org/10.5194/acp-22-14209-2022, https://doi.org/10.5194/acp-22-14209-2022, 2022
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The variability in the meteorological fields during each deployment is highly modulated at a daily to synoptic timescale. This paper, along with part 1, the climatological overview paper, provides a meteorological context for interpreting the airborne measurements gathered during the three ORACLES deployments. This study supports related studies focusing on the detailed investigation of the processes controlling stratocumulus decks, aerosol lifting, transport, and their interactions.
Paul A. Barrett, Steven J. Abel, Hugh Coe, Ian Crawford, Amie Dobracki, James Haywood, Steve Howell, Anthony Jones, Justin Langridge, Greg M. McFarquhar, Graeme J. Nott, Hannah Price, Jens Redemann, Yohei Shinozuka, Kate Szpek, Jonathan W. Taylor, Robert Wood, Huihui Wu, Paquita Zuidema, Stéphane Bauguitte, Ryan Bennett, Keith Bower, Hong Chen, Sabrina Cochrane, Michael Cotterell, Nicholas Davies, David Delene, Connor Flynn, Andrew Freedman, Steffen Freitag, Siddhant Gupta, David Noone, Timothy B. Onasch, James Podolske, Michael R. Poellot, Sebastian Schmidt, Stephen Springston, Arthur J. Sedlacek III, Jamie Trembath, Alan Vance, Maria A. Zawadowicz, and Jianhao Zhang
Atmos. Meas. Tech., 15, 6329–6371, https://doi.org/10.5194/amt-15-6329-2022, https://doi.org/10.5194/amt-15-6329-2022, 2022
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To better understand weather and climate, it is vital to go into the field and collect observations. Often measurements take place in isolation, but here we compared data from two aircraft and one ground-based site. This was done in order to understand how well measurements made on one platform compared to those made on another. Whilst this is easy to do in a controlled laboratory setting, it is more challenging in the real world, and so these comparisons are as valuable as they are rare.
Eva-Lou Edwards, Jeffrey S. Reid, Peng Xian, Sharon P. Burton, Anthony L. Cook, Ewan C. Crosbie, Marta A. Fenn, Richard A. Ferrare, Sean W. Freeman, John W. Hair, David B. Harper, Chris A. Hostetler, Claire E. Robinson, Amy Jo Scarino, Michael A. Shook, G. Alexander Sokolowsky, Susan C. van den Heever, Edward L. Winstead, Sarah Woods, Luke D. Ziemba, and Armin Sorooshian
Atmos. Chem. Phys., 22, 12961–12983, https://doi.org/10.5194/acp-22-12961-2022, https://doi.org/10.5194/acp-22-12961-2022, 2022
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This study compares NAAPS-RA model simulations of aerosol optical thickness (AOT) and extinction to those retrieved with a high spectral resolution lidar near the Philippines. Agreement for AOT was good, and extinction agreement was strongest below 1500 m. Substituting dropsonde relative humidities into NAAPS-RA did not drastically improve agreement, and we discuss potential reasons why. Accurately modeling future conditions in this region is crucial due to its susceptibility to climate change.
Siddhant Gupta, Greg M. McFarquhar, Joseph R. O'Brien, Michael R. Poellot, David J. Delene, Ian Chang, Lan Gao, Feng Xu, and Jens Redemann
Atmos. Chem. Phys., 22, 12923–12943, https://doi.org/10.5194/acp-22-12923-2022, https://doi.org/10.5194/acp-22-12923-2022, 2022
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The ability of NASA’s Terra and Aqua satellites to retrieve cloud properties and estimate the changes in cloud properties due to aerosol–cloud interactions (ACI) was examined. There was good agreement between satellite retrievals and in situ measurements over the southeast Atlantic Ocean. This suggests that, combined with information on aerosol properties, satellite retrievals of cloud properties can be used to study ACI over larger domains and longer timescales in the absence of in situ data.
Michael S. Diamond, Pablo E. Saide, Paquita Zuidema, Andrew S. Ackerman, Sarah J. Doherty, Ann M. Fridlind, Hamish Gordon, Calvin Howes, Jan Kazil, Takanobu Yamaguchi, Jianhao Zhang, Graham Feingold, and Robert Wood
Atmos. Chem. Phys., 22, 12113–12151, https://doi.org/10.5194/acp-22-12113-2022, https://doi.org/10.5194/acp-22-12113-2022, 2022
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Smoke from southern Africa blankets the southeast Atlantic from June-October, overlying a major transition region between overcast and scattered clouds. The smoke affects Earth's radiation budget by absorbing sunlight and changing cloud properties. We investigate these effects in regional climate and large eddy simulation models based on international field campaigns. We find that large-scale circulation changes more strongly affect cloud transitions than smoke microphysical effects in our case.
Samuel E. LeBlanc, Michal Segal-Rozenhaimer, Jens Redemann, Connor Flynn, Roy R. Johnson, Stephen E. Dunagan, Robert Dahlgren, Jhoon Kim, Myungje Choi, Arlindo da Silva, Patricia Castellanos, Qian Tan, Luke Ziemba, Kenneth Lee Thornhill, and Meloë Kacenelenbogen
Atmos. Chem. Phys., 22, 11275–11304, https://doi.org/10.5194/acp-22-11275-2022, https://doi.org/10.5194/acp-22-11275-2022, 2022
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Airborne observations of atmospheric particles and pollution over Korea during a field campaign in May–June 2016 showed that the smallest atmospheric particles are present in the lowest 2 km of the atmosphere. The aerosol size is more spatially variable than optical thickness. We show this with remote sensing (4STAR), in situ (LARGE) observations, satellite measurements (GOCI), and modeled properties (MERRA-2), and it is contrary to the current understanding.
Joshin Kumar, Theo Paik, Nishit J. Shetty, Patrick Sheridan, Allison C. Aiken, Manvendra K. Dubey, and Rajan K. Chakrabarty
Atmos. Meas. Tech., 15, 4569–4583, https://doi.org/10.5194/amt-15-4569-2022, https://doi.org/10.5194/amt-15-4569-2022, 2022
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Accurate long-term measurement of aerosol light absorption is vital for assessing direct aerosol radiative forcing. Light absorption by aerosols at the US Department of Energy long-term climate monitoring SGP site is measured using the Particle Soot Absorption Photometer (PSAP), which suffers from artifacts and biases difficult to quantify. Machine learning offers a promising path forward to correct for biases in the long-term absorption dataset at the SGP site and similar Class-I areas.
Jessica Danker, Odran Sourdeval, Isabel L. McCoy, Robert Wood, and Anna Possner
Atmos. Chem. Phys., 22, 10247–10265, https://doi.org/10.5194/acp-22-10247-2022, https://doi.org/10.5194/acp-22-10247-2022, 2022
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Using spaceborne lidar-radar retrievals, we show that seasonal changes in cloud phase outweigh changes in cloud-phase statistics across cloud morphologies at given cloud-top temperatures. These results show that cloud morphology does not seem to pose a primary constraint on cloud-phase statistics in the Southern Ocean. Meanwhile, larger changes in in-cloud albedo across cloud morphologies are observed in supercooled liquid rather than mixed-phase stratocumuli.
Harshvardhan Harshvardhan, Richard Ferrare, Sharon Burton, Johnathan Hair, Chris Hostetler, David Harper, Anthony Cook, Marta Fenn, Amy Jo Scarino, Eduard Chemyakin, and Detlef Müller
Atmos. Chem. Phys., 22, 9859–9876, https://doi.org/10.5194/acp-22-9859-2022, https://doi.org/10.5194/acp-22-9859-2022, 2022
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The evolution of aerosol in biomass burning smoke plumes that travel over marine clouds off the Atlantic coast of central Africa was studied using measurements made by a lidar deployed on a high-altitude aircraft. The main finding was that the physical properties of aerosol do not change appreciably once the plume has left land and travels over the ocean over a timescale of 1 to 2 d. Almost all particles in the plume are of radius less than 1 micrometer and spherical in shape.
Caroline Dang, Michal Segal-Rozenhaimer, Haochi Che, Lu Zhang, Paola Formenti, Jonathan Taylor, Amie Dobracki, Sara Purdue, Pui-Shan Wong, Athanasios Nenes, Arthur Sedlacek III, Hugh Coe, Jens Redemann, Paquita Zuidema, Steven Howell, and James Haywood
Atmos. Chem. Phys., 22, 9389–9412, https://doi.org/10.5194/acp-22-9389-2022, https://doi.org/10.5194/acp-22-9389-2022, 2022
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Transmission electron microscopy was used to analyze aged African smoke particles and how the smoke interacts with the marine atmosphere. We found that the volatility of organic aerosol increases with biomass burning plume age, that black carbon is often mixed with potassium salts and that the marine atmosphere can incorporate Na and Cl into smoke particles. Marine salts are more processed when mixed with smoke plumes, and there are interesting Cl-rich yet Na-absent marine particles.
Lu Zhang, Michal Segal-Rozenhaimer, Haochi Che, Caroline Dang, Arthur J. Sedlacek III, Ernie R. Lewis, Amie Dobracki, Jenny P. S. Wong, Paola Formenti, Steven G. Howell, and Athanasios Nenes
Atmos. Chem. Phys., 22, 9199–9213, https://doi.org/10.5194/acp-22-9199-2022, https://doi.org/10.5194/acp-22-9199-2022, 2022
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Widespread biomass burning (BB) events occur annually in Africa and contribute ~ 1 / 3 of global BB emissions, which contain a large family of light-absorbing organics, known as brown carbon (BrC), whose absorption of incident radiation is difficult to estimate, leading to large uncertainties in the global radiative forcing estimation. This study quantifies the BrC absorption of aged BB particles and highlights the potential presence of absorbing iron oxides in this climatically important region.
Haochi Che, Michal Segal-Rozenhaimer, Lu Zhang, Caroline Dang, Paquita Zuidema, Arthur J. Sedlacek III, Xiaoye Zhang, and Connor Flynn
Atmos. Chem. Phys., 22, 8767–8785, https://doi.org/10.5194/acp-22-8767-2022, https://doi.org/10.5194/acp-22-8767-2022, 2022
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A 17-month in situ study on Ascension Island found low single-scattering albedo and strong absorption enhancement of the marine boundary layer aerosols during biomass burnings on the African continent, along with apparent patterns of regular monthly variability. We further discuss the characteristics and drivers behind these changes and find that biomass burning conditions in Africa may be the main factor influencing the optical properties of marine boundary aerosols.
Meloë S. F. Kacenelenbogen, Qian Tan, Sharon P. Burton, Otto P. Hasekamp, Karl D. Froyd, Yohei Shinozuka, Andreas J. Beyersdorf, Luke Ziemba, Kenneth L. Thornhill, Jack E. Dibb, Taylor Shingler, Armin Sorooshian, Reed W. Espinosa, Vanderlei Martins, Jose L. Jimenez, Pedro Campuzano-Jost, Joshua P. Schwarz, Matthew S. Johnson, Jens Redemann, and Gregory L. Schuster
Atmos. Chem. Phys., 22, 3713–3742, https://doi.org/10.5194/acp-22-3713-2022, https://doi.org/10.5194/acp-22-3713-2022, 2022
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The impact of aerosols on Earth's radiation budget and human health is important and strongly depends on their composition. One desire of our scientific community is to derive the composition of the aerosol from satellite sensors. However, satellites observe aerosol optical properties (and not aerosol composition) based on remote sensing instrumentation. This study assesses how much aerosol optical properties can tell us about aerosol composition.
Matthew S. Norgren, John Wood, K. Sebastian Schmidt, Bastiaan van Diedenhoven, Snorre A. Stamnes, Luke D. Ziemba, Ewan C. Crosbie, Michael A. Shook, A. Scott Kittelman, Samuel E. LeBlanc, Stephen Broccardo, Steffen Freitag, and Jeffrey S. Reid
Atmos. Meas. Tech., 15, 1373–1394, https://doi.org/10.5194/amt-15-1373-2022, https://doi.org/10.5194/amt-15-1373-2022, 2022
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A new spectral instrument (SPN-S), with the ability to partition solar radiation into direct and diffuse components, is used in airborne settings to study the optical properties of aerosols and cirrus. It is a low-cost and mechanically simple system but has higher measurement uncertainty than existing standards. This challenge is overcome by utilizing the unique measurement capabilities to develop new retrieval techniques. Validation is done with data from two NASA airborne research campaigns.
Matthew W. Christensen, Andrew Gettelman, Jan Cermak, Guy Dagan, Michael Diamond, Alyson Douglas, Graham Feingold, Franziska Glassmeier, Tom Goren, Daniel P. Grosvenor, Edward Gryspeerdt, Ralph Kahn, Zhanqing Li, Po-Lun Ma, Florent Malavelle, Isabel L. McCoy, Daniel T. McCoy, Greg McFarquhar, Johannes Mülmenstädt, Sandip Pal, Anna Possner, Adam Povey, Johannes Quaas, Daniel Rosenfeld, Anja Schmidt, Roland Schrödner, Armin Sorooshian, Philip Stier, Velle Toll, Duncan Watson-Parris, Robert Wood, Mingxi Yang, and Tianle Yuan
Atmos. Chem. Phys., 22, 641–674, https://doi.org/10.5194/acp-22-641-2022, https://doi.org/10.5194/acp-22-641-2022, 2022
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Trace gases and aerosols (tiny airborne particles) are released from a variety of point sources around the globe. Examples include volcanoes, industrial chimneys, forest fires, and ship stacks. These sources provide opportunistic experiments with which to quantify the role of aerosols in modifying cloud properties. We review the current state of understanding on the influence of aerosol on climate built from the wide range of natural and anthropogenic laboratories investigated in recent decades.
Sabrina P. Cochrane, K. Sebastian Schmidt, Hong Chen, Peter Pilewskie, Scott Kittelman, Jens Redemann, Samuel LeBlanc, Kristina Pistone, Michal Segal Rozenhaimer, Meloë Kacenelenbogen, Yohei Shinozuka, Connor Flynn, Rich Ferrare, Sharon Burton, Chris Hostetler, Marc Mallet, and Paquita Zuidema
Atmos. Meas. Tech., 15, 61–77, https://doi.org/10.5194/amt-15-61-2022, https://doi.org/10.5194/amt-15-61-2022, 2022
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This work presents heating rates derived from aircraft observations from the 2016 and 2017 field campaigns of ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS). We separate the total heating rates into aerosol and gas (primarily water vapor) absorption and explore some of the co-variability of heating rate profiles and their primary drivers, leading to the development of a new concept: the heating rate efficiency (HRE; the heating rate per unit aerosol extinction).
Amie Dobracki, Paquita Zuidema, Steve Howell, Pablo Saide, Steffen Freitag, Allison C. Aiken, Sharon P. Burton, Arthur J. Sedlacek III, Jens Redemann, and Robert Wood
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2021-1081, https://doi.org/10.5194/acp-2021-1081, 2022
Preprint withdrawn
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The global maximum of shortwave-absorbing aerosol above cloud occurs above the southeast Atlantic, where the biomass-burning aerosol provides a distinct aerosol radiative warming of regional climate. The smoke aerosols are unusually highly absorbing of sunlight. This study seeks to understand the cause. We conclude the aerosol is already strongly absorbing at the fire emission source, but that chemical aging, through encouraging a net loss of organic aerosol, also contributes.
Sarah J. Doherty, Pablo E. Saide, Paquita Zuidema, Yohei Shinozuka, Gonzalo A. Ferrada, Hamish Gordon, Marc Mallet, Kerry Meyer, David Painemal, Steven G. Howell, Steffen Freitag, Amie Dobracki, James R. Podolske, Sharon P. Burton, Richard A. Ferrare, Calvin Howes, Pierre Nabat, Gregory R. Carmichael, Arlindo da Silva, Kristina Pistone, Ian Chang, Lan Gao, Robert Wood, and Jens Redemann
Atmos. Chem. Phys., 22, 1–46, https://doi.org/10.5194/acp-22-1-2022, https://doi.org/10.5194/acp-22-1-2022, 2022
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Between July and October, biomass burning smoke is advected over the southeastern Atlantic Ocean, leading to climate forcing. Model calculations of forcing by this plume vary significantly in both magnitude and sign. This paper compares aerosol and cloud properties observed during three NASA ORACLES field campaigns to the same in four models. It quantifies modeled biases in properties key to aerosol direct radiative forcing and evaluates how these biases propagate to biases in forcing.
Steven G. Howell, Steffen Freitag, Amie Dobracki, Nikolai Smirnow, and Arthur J. Sedlacek III
Atmos. Meas. Tech., 14, 7381–7404, https://doi.org/10.5194/amt-14-7381-2021, https://doi.org/10.5194/amt-14-7381-2021, 2021
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Small particles in the air have important effects on visibility, clouds, and human health. For the ORACLES project we got a new particle sizing instrument that is fast, works over the most important particle sizes, and avoids some of the issues that plague other optical particle sizers. Unfortunately it sees some particles much smaller than they really are, likely because they heat up and evaporate. We show a crude correction and speculate why these particles heat up much more than expected.
Ju-Mee Ryoo, Leonhard Pfister, Rei Ueyama, Paquita Zuidema, Robert Wood, Ian Chang, and Jens Redemann
Atmos. Chem. Phys., 21, 16689–16707, https://doi.org/10.5194/acp-21-16689-2021, https://doi.org/10.5194/acp-21-16689-2021, 2021
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Part 1 of the meteorological overview paper highlights the anomalous meteorological characteristics during the ORACLES deployment compared to the climatological mean at monthly timescales. The upper-level wave disturbance and the associated anomalous circulation explain the weakening of AEJ-S through the reduction of the strength of the heat low over the land during August 2017. This may also help explain the anomalously low aerosol optical depth observed in the August 2017 ORACLES deployment.
Raphaela Vogel, Heike Konow, Hauke Schulz, and Paquita Zuidema
Atmos. Chem. Phys., 21, 16609–16630, https://doi.org/10.5194/acp-21-16609-2021, https://doi.org/10.5194/acp-21-16609-2021, 2021
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The shallow cumulus clouds that populate the trade-wind regions can produce substantial amounts of rain. Before reaching the surface, part of the rain can evaporate and form pools of cold air that spread at the surface as density currents. We use 10 years of data from Barbados to show that such cold pools occur on 3 out of 4 d, that cold-pool periods are 90 % cloudier relative to the average winter conditions, and that they are connected to specific patterns of mesoscale cloud organization.
Rachel Atlas, Johannes Mohrmann, Joseph Finlon, Jeremy Lu, Ian Hsiao, Robert Wood, and Minghui Diao
Atmos. Meas. Tech., 14, 7079–7101, https://doi.org/10.5194/amt-14-7079-2021, https://doi.org/10.5194/amt-14-7079-2021, 2021
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Many clouds with temperatures between 0 °C and −40 °C contain both liquid and ice particles, and the ratio of liquid to ice particles influences how the clouds interact with radiation and moderate Earth's climate. We use a machine learning method called random forest to classify images of individual cloud particles as either liquid or ice. We apply our algorithm to images captured by aircraft within clouds overlying the Southern Ocean, and we find that it outperforms two existing algorithms.
Rose M. Miller, Greg M. McFarquhar, Robert M. Rauber, Joseph R. O'Brien, Siddhant Gupta, Michal Segal-Rozenhaimer, Amie N. Dobracki, Arthur J. Sedlacek, Sharon P. Burton, Steven G. Howell, Steffen Freitag, and Caroline Dang
Atmos. Chem. Phys., 21, 14815–14831, https://doi.org/10.5194/acp-21-14815-2021, https://doi.org/10.5194/acp-21-14815-2021, 2021
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A large stratocumulus cloud deck resides off the west coast of central Africa. Biomass burning in Africa produces a large plume of aerosol that is carried by the wind over this stratocumulus cloud deck. This paper shows that particles with sizes from 0.01 to 1 mm reside within this plume. Past studies have shown that biomass burning produces such particles, but this is the first study to show that they can be transported westward, over long distances, to the Atlantic stratocumulus cloud deck.
Robert Wood
Atmos. Chem. Phys., 21, 14507–14533, https://doi.org/10.5194/acp-21-14507-2021, https://doi.org/10.5194/acp-21-14507-2021, 2021
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A simple model is described to assess the potential for increasing solar reflection by augmenting the aerosol population below marine low clouds, which increases the concentration of cloud droplets. The model is used to predict global cooling from marine cloud brightening climate intervention as a function of the quantity, size, and lifetime of salt particles injected per sprayer, the number of sprayers deployed, the cloud updraft speed, and unperturbed aerosol size distribution.
Xinxin Ye, Pargoal Arab, Ravan Ahmadov, Eric James, Georg A. Grell, Bradley Pierce, Aditya Kumar, Paul Makar, Jack Chen, Didier Davignon, Greg R. Carmichael, Gonzalo Ferrada, Jeff McQueen, Jianping Huang, Rajesh Kumar, Louisa Emmons, Farren L. Herron-Thorpe, Mark Parrington, Richard Engelen, Vincent-Henri Peuch, Arlindo da Silva, Amber Soja, Emily Gargulinski, Elizabeth Wiggins, Johnathan W. Hair, Marta Fenn, Taylor Shingler, Shobha Kondragunta, Alexei Lyapustin, Yujie Wang, Brent Holben, David M. Giles, and Pablo E. Saide
Atmos. Chem. Phys., 21, 14427–14469, https://doi.org/10.5194/acp-21-14427-2021, https://doi.org/10.5194/acp-21-14427-2021, 2021
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Wildfire smoke has crucial impacts on air quality, while uncertainties in the numerical forecasts remain significant. We present an evaluation of 12 real-time forecasting systems. Comparison of predicted smoke emissions suggests a large spread in magnitudes, with temporal patterns deviating from satellite detections. The performance for AOD and surface PM2.5 and their discrepancies highlighted the role of accurately represented spatiotemporal emission profiles in improving smoke forecasts.
Zixia Liu, Martin Osborne, Karen Anderson, Jamie D. Shutler, Andy Wilson, Justin Langridge, Steve H. L. Yim, Hugh Coe, Suresh Babu, Sreedharan K. Satheesh, Paquita Zuidema, Tao Huang, Jack C. H. Cheng, and James Haywood
Atmos. Meas. Tech., 14, 6101–6118, https://doi.org/10.5194/amt-14-6101-2021, https://doi.org/10.5194/amt-14-6101-2021, 2021
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This paper first validates the performance of an advanced aerosol observation instrument POPS against a reference instrument and examines any biases introduced by operating it on a quadcopter drone. The results show the POPS performs relatively well on the ground. The impact of the UAV rotors on the POPS is small at low wind speeds, but when operating under higher wind speeds, larger discrepancies occur. It appears that the POPS measures sub-micron aerosol particles more accurately on the UAV.
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Short summary
Southern Africa produces approximately one-third of the world’s carbon from fires. The thick smoke layer can flow westward, interacting with the southeastern Atlantic cloud deck. The net radiative impact can alter regional circulation patterns, impacting rainfall over Africa. We find that the smoke is highly absorbing of sunlight, mostly because it contains more black carbon than smoke over the Northern Hemisphere.
Southern Africa produces approximately one-third of the world’s carbon from fires. The thick...
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