A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERES

By combining Collection 6 Moderate Resolution and Imaging Spectroradiometer (MODIS) and Version 22 Multi-angle Imaging Spectroradiometer (MISR) aerosol products with Cloud and Earth's Radiant Energy System (CERES) flux products, the aerosol optical thickness (AOT, at 0.55 µm) and shortwave...

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Main Authors: R. Alfaro-Contreras, J. Zhang, J. S. Reid, S. Christopher
Format: Article
Language:English
Published: Copernicus Publications 2017-11-01
Series:Atmospheric Chemistry and Physics
Online Access:https://www.atmos-chem-phys.net/17/13849/2017/acp-17-13849-2017.pdf
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author R. Alfaro-Contreras
J. Zhang
J. S. Reid
S. Christopher
author_facet R. Alfaro-Contreras
J. Zhang
J. S. Reid
S. Christopher
author_sort R. Alfaro-Contreras
collection DOAJ
description By combining Collection 6 Moderate Resolution and Imaging Spectroradiometer (MODIS) and Version 22 Multi-angle Imaging Spectroradiometer (MISR) aerosol products with Cloud and Earth's Radiant Energy System (CERES) flux products, the aerosol optical thickness (AOT, at 0.55 µm) and shortwave (SW) aerosol radiative effect (SWARE) trends are studied over ocean for the near-full Terra (2000–2015) and Aqua (2002–2015) data records. Despite differences in sampling methods, regional SWARE and AOT trends are highly correlated with one another. Over global oceans, weak SWARE (cloud-free SW flux) and AOT trends of 0.5–0.6 W m<sup>−2</sup> (−0.5 to −0.6 W m<sup>−2</sup>) and 0.002 AOT decade<sup>−1</sup> are found using Terra data. Near-zero AOT and SWARE trends are also found for using Aqua data, regardless of the angular distribution models (ADMs) used. Regionally, positive AOT and cloud-free SW flux (negative SWARE) trends are found over the Bay of Bengal, the Arabian Sea, the Arabian/Persian Gulf and the Red Sea, while statistically significant negative trends are derived over the Mediterranean Sea and the eastern US coast. In addition, the global mean instantaneous SW aerosol direct forcing efficiencies are found to be ∼ −60 W m<sup>−2</sup> AOT<sup>−1</sup>, with corresponding SWARE values of ∼ −7 W m<sup>−2</sup> from both Aqua and Terra data, again regardless of CERES ADMs used. Regionally, SW aerosol direct forcing efficiency values of  ∼ −40 W m<sup>−2</sup> AOT<sup>−1</sup> are found over the southwest coast of Africa where smoke aerosol particles dominate in summer. Larger (in magnitude) SW aerosol direct forcing efficiency values of −50 to −80 W m<sup>−2</sup> AOT<sup>−1</sup> are found over several other dust- and pollutant-aerosol-dominated regions. Lastly, the AOT and SWARE trends from this study are also intercompared with aerosol trends (such as active-based ones) from several previous studies. Findings suggest that a cohesive understanding of the changing aerosol skies can be achieved through the analysis of observations from both passive- and active-based analyses, as well as from both narrowband and broadband datasets.
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spelling doaj.art-68daa483f86445df92a1fb0a1aec64282022-12-21T22:55:50ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242017-11-0117138491386810.5194/acp-17-13849-2017A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERESR. Alfaro-Contreras0J. Zhang1J. S. Reid2S. Christopher3Department of Atmospheric Sciences, University of North Dakota, Grand Forks, ND, USADepartment of Atmospheric Sciences, University of North Dakota, Grand Forks, ND, USAMarine Meteorology Division, Naval Research Laboratory, Monterey, CA, USADepartment of Atmospheric Science, The University of Alabama in Huntsville, Huntsville, AL, USABy combining Collection 6 Moderate Resolution and Imaging Spectroradiometer (MODIS) and Version 22 Multi-angle Imaging Spectroradiometer (MISR) aerosol products with Cloud and Earth's Radiant Energy System (CERES) flux products, the aerosol optical thickness (AOT, at 0.55 µm) and shortwave (SW) aerosol radiative effect (SWARE) trends are studied over ocean for the near-full Terra (2000–2015) and Aqua (2002–2015) data records. Despite differences in sampling methods, regional SWARE and AOT trends are highly correlated with one another. Over global oceans, weak SWARE (cloud-free SW flux) and AOT trends of 0.5–0.6 W m<sup>−2</sup> (−0.5 to −0.6 W m<sup>−2</sup>) and 0.002 AOT decade<sup>−1</sup> are found using Terra data. Near-zero AOT and SWARE trends are also found for using Aqua data, regardless of the angular distribution models (ADMs) used. Regionally, positive AOT and cloud-free SW flux (negative SWARE) trends are found over the Bay of Bengal, the Arabian Sea, the Arabian/Persian Gulf and the Red Sea, while statistically significant negative trends are derived over the Mediterranean Sea and the eastern US coast. In addition, the global mean instantaneous SW aerosol direct forcing efficiencies are found to be ∼ −60 W m<sup>−2</sup> AOT<sup>−1</sup>, with corresponding SWARE values of ∼ −7 W m<sup>−2</sup> from both Aqua and Terra data, again regardless of CERES ADMs used. Regionally, SW aerosol direct forcing efficiency values of  ∼ −40 W m<sup>−2</sup> AOT<sup>−1</sup> are found over the southwest coast of Africa where smoke aerosol particles dominate in summer. Larger (in magnitude) SW aerosol direct forcing efficiency values of −50 to −80 W m<sup>−2</sup> AOT<sup>−1</sup> are found over several other dust- and pollutant-aerosol-dominated regions. Lastly, the AOT and SWARE trends from this study are also intercompared with aerosol trends (such as active-based ones) from several previous studies. Findings suggest that a cohesive understanding of the changing aerosol skies can be achieved through the analysis of observations from both passive- and active-based analyses, as well as from both narrowband and broadband datasets.https://www.atmos-chem-phys.net/17/13849/2017/acp-17-13849-2017.pdf
spellingShingle R. Alfaro-Contreras
J. Zhang
J. S. Reid
S. Christopher
A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERES
Atmospheric Chemistry and Physics
title A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERES
title_full A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERES
title_fullStr A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERES
title_full_unstemmed A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERES
title_short A study of 15-year aerosol optical thickness and direct shortwave aerosol radiative effect trends using MODIS, MISR, CALIOP and CERES
title_sort a study of 15 year aerosol optical thickness and direct shortwave aerosol radiative effect trends using modis misr caliop and ceres
url https://www.atmos-chem-phys.net/17/13849/2017/acp-17-13849-2017.pdf
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