Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds
Aerosol indirect effects have potentially large impacts on the Arctic Ocean surface energy budget, but model estimates of regional-scale aerosol indirect effects are highly uncertain and poorly validated by observations. Here we demonstrate a new way to quantitatively estimate aerosol indirect effec...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20170007357 2023-05-15T14:48:40+02:00 Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds Kahn, Ralph A. Stohl, Andreas Zamora, Lauren M. Moore, Richard Sawamura, Patricia Mccomiskey, Allison Eckhardt, Sabine Unclassified, Unlimited, Publicly available June 20, 2017 application/pdf http://hdl.handle.net/2060/20170007357 unknown Document ID: 20170007357 http://hdl.handle.net/2060/20170007357 Copyright, Public use permitted CASI Geosciences (General) GSFC-E-DAA-TN44853 Atmospheric Chemistry and Physics (ISSN 1680-7316) (e-ISSN 1680-7324); 17; 12; 7311-7332 2017 ftnasantrs 2019-07-20T23:29:14Z Aerosol indirect effects have potentially large impacts on the Arctic Ocean surface energy budget, but model estimates of regional-scale aerosol indirect effects are highly uncertain and poorly validated by observations. Here we demonstrate a new way to quantitatively estimate aerosol indirect effects on a regional scale from remote sensing observations. In this study, we focus on nighttime, optically thin, predominantly liquid clouds. The method is based on differences in cloud physical and microphysical characteristics in carefully selected clean, average, and aerosol-impacted conditions. The cloud subset of focus covers just approximately 5 % of cloudy Arctic Ocean regions, warming the Arctic Ocean surface by approximately 1-1.4 W m(exp -2) regionally during polar night. However, within this cloud subset, aerosol and cloud conditions can be determined with high confidence using CALIPSO and CloudSat data and model output. This cloud subset is generally susceptible to aerosols, with a polar nighttime estimated maximum regionally integrated indirect cooling effect of approximately 0.11 W m(exp 2) at the Arctic sea ice surface (approximately 8 % of the clean background cloud effect), excluding cloud fraction changes. Aerosol presence is related to reduced precipitation, cloud thickness, and radar reflectivity, and in some cases, an increased likelihood of cloud presence in the liquid phase. These observations are inconsistent with a glaciation indirect effect and are consistent with either a deactivation effect or less-efficient secondary ice formation related to smaller liquid cloud droplets. However, this cloud subset shows large differences in surface and meteorological forcing in shallow and higher-altitude clouds and between sea ice and open-ocean regions. For example, optically thin, predominantly liquid clouds are much more likely to overlay another cloud over the open ocean, which may reduce aerosol indirect effects on the surface. Also, shallow clouds over open ocean do not appear to respond to aerosols as strongly as clouds over stratified sea ice environments, indicating a larger influence of meteorological forcing over aerosol microphysics in these types of clouds over the rapidly changing Arctic Ocean. Other/Unknown Material Arctic Arctic Ocean polar night Sea ice NASA Technical Reports Server (NTRS) Arctic Arctic Ocean |
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Open Polar |
collection |
NASA Technical Reports Server (NTRS) |
op_collection_id |
ftnasantrs |
language |
unknown |
topic |
Geosciences (General) |
spellingShingle |
Geosciences (General) Kahn, Ralph A. Stohl, Andreas Zamora, Lauren M. Moore, Richard Sawamura, Patricia Mccomiskey, Allison Eckhardt, Sabine Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds |
topic_facet |
Geosciences (General) |
description |
Aerosol indirect effects have potentially large impacts on the Arctic Ocean surface energy budget, but model estimates of regional-scale aerosol indirect effects are highly uncertain and poorly validated by observations. Here we demonstrate a new way to quantitatively estimate aerosol indirect effects on a regional scale from remote sensing observations. In this study, we focus on nighttime, optically thin, predominantly liquid clouds. The method is based on differences in cloud physical and microphysical characteristics in carefully selected clean, average, and aerosol-impacted conditions. The cloud subset of focus covers just approximately 5 % of cloudy Arctic Ocean regions, warming the Arctic Ocean surface by approximately 1-1.4 W m(exp -2) regionally during polar night. However, within this cloud subset, aerosol and cloud conditions can be determined with high confidence using CALIPSO and CloudSat data and model output. This cloud subset is generally susceptible to aerosols, with a polar nighttime estimated maximum regionally integrated indirect cooling effect of approximately 0.11 W m(exp 2) at the Arctic sea ice surface (approximately 8 % of the clean background cloud effect), excluding cloud fraction changes. Aerosol presence is related to reduced precipitation, cloud thickness, and radar reflectivity, and in some cases, an increased likelihood of cloud presence in the liquid phase. These observations are inconsistent with a glaciation indirect effect and are consistent with either a deactivation effect or less-efficient secondary ice formation related to smaller liquid cloud droplets. However, this cloud subset shows large differences in surface and meteorological forcing in shallow and higher-altitude clouds and between sea ice and open-ocean regions. For example, optically thin, predominantly liquid clouds are much more likely to overlay another cloud over the open ocean, which may reduce aerosol indirect effects on the surface. Also, shallow clouds over open ocean do not appear to respond to aerosols as strongly as clouds over stratified sea ice environments, indicating a larger influence of meteorological forcing over aerosol microphysics in these types of clouds over the rapidly changing Arctic Ocean. |
format |
Other/Unknown Material |
author |
Kahn, Ralph A. Stohl, Andreas Zamora, Lauren M. Moore, Richard Sawamura, Patricia Mccomiskey, Allison Eckhardt, Sabine |
author_facet |
Kahn, Ralph A. Stohl, Andreas Zamora, Lauren M. Moore, Richard Sawamura, Patricia Mccomiskey, Allison Eckhardt, Sabine |
author_sort |
Kahn, Ralph A. |
title |
Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds |
title_short |
Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds |
title_full |
Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds |
title_fullStr |
Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds |
title_full_unstemmed |
Aerosol Indirect Effects on the Nighttime Arctic Ocean Surface from Thin, Predominantly Liquid Clouds |
title_sort |
aerosol indirect effects on the nighttime arctic ocean surface from thin, predominantly liquid clouds |
publishDate |
2017 |
url |
http://hdl.handle.net/2060/20170007357 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean polar night Sea ice |
genre_facet |
Arctic Arctic Ocean polar night Sea ice |
op_source |
CASI |
op_relation |
Document ID: 20170007357 http://hdl.handle.net/2060/20170007357 |
op_rights |
Copyright, Public use permitted |
_version_ |
1766319758619181056 |