Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions
Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4) general circulation model (GCM) to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Af...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20110014290 2023-05-15T17:35:59+02:00 Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions Sud, Y. C. Walker, G. Wilcox, E. M. Unclassified, Unlimited, Publicly available October 23, 2009 application/pdf http://hdl.handle.net/2060/20110014290 unknown Document ID: 20110014290 http://hdl.handle.net/2060/20110014290 Copyright, Distribution as joint owner in the copyright CASI Meteorology and Climatology GSFC.JA.4378.2011 Annales Geophysicae; 27; 4009-4021 2009 ftnasantrs 2019-07-21T01:01:00Z Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4) general circulation model (GCM) to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Africa, and North and South America. Part 1 of this paper addresses the responses to aerosol perturbations in India and Africa. This paper presents the same for aerosol perturbations over the Americas. GEOS-4 is forced with prescribed aerosols based on climatological data, which interact with clouds using a prognostic scheme for cloud microphysics including aerosol nucleation of water and ice cloud hydrometeors. In clear-sky conditions the aerosols interact with radiation. Thus the model includes comprehensive physics describing the aerosol direct and indirect effects on climate (hereafter ADE and AIE respectively). Each simulation is started from analyzed initial conditions for 1 May and was integrated through June-July-August of each of the six years: 1982 1987 to provide a 6-ensemble set. Results are presented for the difference between simulations with double the climatological aerosol concentration and one-half the climatological aerosol concentration for three experiments: two where the ADE and AIE are applied separately and one in which both the ADE and AIE are applied. The ADE and AIE both yield reductions in net radiation at the top of the atmosphere and surface while the direct absorption of shortwave radiation contributes a net radiative heating in the atmosphere. A large net heating of the atmosphere is also apparent over the subtropical North Atlantic Ocean that is attributable to the large aerosol perturbation imposed over Africa. This atmospheric warming and the depression of the surface pressure over North America contribute to a northward shift of the inter-Tropical Convergence Zone over northern America, an increase in precipitation over Central America and the Caribbean, and an enhancement of convergence in the North American monsoon region. Other/Unknown Material North Atlantic NASA Technical Reports Server (NTRS) |
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Open Polar |
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NASA Technical Reports Server (NTRS) |
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ftnasantrs |
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topic |
Meteorology and Climatology |
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Meteorology and Climatology Sud, Y. C. Walker, G. Wilcox, E. M. Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions |
topic_facet |
Meteorology and Climatology |
description |
Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4) general circulation model (GCM) to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Africa, and North and South America. Part 1 of this paper addresses the responses to aerosol perturbations in India and Africa. This paper presents the same for aerosol perturbations over the Americas. GEOS-4 is forced with prescribed aerosols based on climatological data, which interact with clouds using a prognostic scheme for cloud microphysics including aerosol nucleation of water and ice cloud hydrometeors. In clear-sky conditions the aerosols interact with radiation. Thus the model includes comprehensive physics describing the aerosol direct and indirect effects on climate (hereafter ADE and AIE respectively). Each simulation is started from analyzed initial conditions for 1 May and was integrated through June-July-August of each of the six years: 1982 1987 to provide a 6-ensemble set. Results are presented for the difference between simulations with double the climatological aerosol concentration and one-half the climatological aerosol concentration for three experiments: two where the ADE and AIE are applied separately and one in which both the ADE and AIE are applied. The ADE and AIE both yield reductions in net radiation at the top of the atmosphere and surface while the direct absorption of shortwave radiation contributes a net radiative heating in the atmosphere. A large net heating of the atmosphere is also apparent over the subtropical North Atlantic Ocean that is attributable to the large aerosol perturbation imposed over Africa. This atmospheric warming and the depression of the surface pressure over North America contribute to a northward shift of the inter-Tropical Convergence Zone over northern America, an increase in precipitation over Central America and the Caribbean, and an enhancement of convergence in the North American monsoon region. |
format |
Other/Unknown Material |
author |
Sud, Y. C. Walker, G. Wilcox, E. M. |
author_facet |
Sud, Y. C. Walker, G. Wilcox, E. M. |
author_sort |
Sud, Y. C. |
title |
Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions |
title_short |
Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions |
title_full |
Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions |
title_fullStr |
Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions |
title_full_unstemmed |
Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions |
title_sort |
sensitivity of boreal-summer circulation and precipitation to atmospheric aerosols in selected regions |
publishDate |
2009 |
url |
http://hdl.handle.net/2060/20110014290 |
op_coverage |
Unclassified, Unlimited, Publicly available |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
CASI |
op_relation |
Document ID: 20110014290 http://hdl.handle.net/2060/20110014290 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766135305124970496 |