Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites
Accurate retrievals of aerosol size distribution are necessary to estimate aerosols' impact on climate and human health. The inversions of the Aerosol Robotic Network (AERONET) usually retrieve bimodal distributions. However, when the inversion is applied to Saharan and Sahelian dust, an additi...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20140013336 2023-05-15T13:06:28+02:00 Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites Lacis, Andrew A. Carlson, Barbara E. Hameed, Sultan Gianelli, Scott M. Unclassified, Unlimited, Publicly available November 19, 2013 application/pdf http://hdl.handle.net/2060/20140013336 unknown Document ID: 20140013336 http://hdl.handle.net/2060/20140013336 Copyright, Distribution as joint owner in the copyright CASI Meteorology and Climatology GSFC-E-DAA-TN12544 Journal of Geophysical Research: Atmospheres (ISSN 2169-8996); 118; 22; 12,661-12,672 2013 ftnasantrs 2019-07-21T00:22:59Z Accurate retrievals of aerosol size distribution are necessary to estimate aerosols' impact on climate and human health. The inversions of the Aerosol Robotic Network (AERONET) usually retrieve bimodal distributions. However, when the inversion is applied to Saharan and Sahelian dust, an additional mode of intermediate size between the coarse and fine modes is sometimes seen. This mode explains peculiarities in the behavior of the Angstrom exponent, along with the fine mode fraction retrieved using the spectral deconvolution algorithm, observed in a March 2006 dust storm. For this study, 15 AERONET sites in northern Africa and on the Atlantic are examined to determine the frequency and properties of the intermediate mode. The mode is observed most frequently at Ilorin in Nigeria. It is also observed at Capo Verde and multiple sites located within the Sahel but much less frequently at sites in the northern Sahara and the Canary Islands. The presence of the intermediate mode coincides with increases in Angstrom exponent, fine mode fraction, single-scattering albedo, and to a lesser extent percent sphericity. The Angstrom exponent decreases with increasing optical depth at most sites when the intermediate mode is present, but the fine mode fraction does not. Single-scattering albedo does not steadily decrease with fine mode fraction when the intermediate mode is present, as it does in typical mixtures of dust and biomass-burning aerosols. Continued investigation is needed to further define the intermediate mode's properties, determine why it differs from most Saharan dust, and identify its climate and health effects. Other/Unknown Material Aerosol Robotic Network 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 |
language |
unknown |
topic |
Meteorology and Climatology |
spellingShingle |
Meteorology and Climatology Lacis, Andrew A. Carlson, Barbara E. Hameed, Sultan Gianelli, Scott M. Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites |
topic_facet |
Meteorology and Climatology |
description |
Accurate retrievals of aerosol size distribution are necessary to estimate aerosols' impact on climate and human health. The inversions of the Aerosol Robotic Network (AERONET) usually retrieve bimodal distributions. However, when the inversion is applied to Saharan and Sahelian dust, an additional mode of intermediate size between the coarse and fine modes is sometimes seen. This mode explains peculiarities in the behavior of the Angstrom exponent, along with the fine mode fraction retrieved using the spectral deconvolution algorithm, observed in a March 2006 dust storm. For this study, 15 AERONET sites in northern Africa and on the Atlantic are examined to determine the frequency and properties of the intermediate mode. The mode is observed most frequently at Ilorin in Nigeria. It is also observed at Capo Verde and multiple sites located within the Sahel but much less frequently at sites in the northern Sahara and the Canary Islands. The presence of the intermediate mode coincides with increases in Angstrom exponent, fine mode fraction, single-scattering albedo, and to a lesser extent percent sphericity. The Angstrom exponent decreases with increasing optical depth at most sites when the intermediate mode is present, but the fine mode fraction does not. Single-scattering albedo does not steadily decrease with fine mode fraction when the intermediate mode is present, as it does in typical mixtures of dust and biomass-burning aerosols. Continued investigation is needed to further define the intermediate mode's properties, determine why it differs from most Saharan dust, and identify its climate and health effects. |
format |
Other/Unknown Material |
author |
Lacis, Andrew A. Carlson, Barbara E. Hameed, Sultan Gianelli, Scott M. |
author_facet |
Lacis, Andrew A. Carlson, Barbara E. Hameed, Sultan Gianelli, Scott M. |
author_sort |
Lacis, Andrew A. |
title |
Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites |
title_short |
Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites |
title_full |
Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites |
title_fullStr |
Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites |
title_full_unstemmed |
Evidence of a Weakly Absorbing Intermediate Mode of Aerosols in AERONET Data from Saharan and Sahelian Sites |
title_sort |
evidence of a weakly absorbing intermediate mode of aerosols in aeronet data from saharan and sahelian sites |
publishDate |
2013 |
url |
http://hdl.handle.net/2060/20140013336 |
op_coverage |
Unclassified, Unlimited, Publicly available |
genre |
Aerosol Robotic Network |
genre_facet |
Aerosol Robotic Network |
op_source |
CASI |
op_relation |
Document ID: 20140013336 http://hdl.handle.net/2060/20140013336 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766006952475754496 |