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Reducing Multisensor Satellite Monthly Mean Aerosol Optical Depth Uncertainty: 1. Objective Assessment of Current AERONET LocationsVarious space-based sensors have been designed and corresponding algorithms developed to retrieve aerosol optical depth (AOD), the very basic aerosol optical property, yet considerable disagreement still exists across these different satellite data sets. Surface-based observations aim to provide ground truth for validating satellite data; hence, their deployment locations should preferably contain as much spatial information as possible, i.e., high spatial representativeness. Using a novel Ensemble Kalman Filter (EnKF)- based approach, we objectively evaluate the spatial representativeness of current Aerosol Robotic Network (AERONET) sites. Multisensor monthly mean AOD data sets from Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, Sea-viewing Wide Field-of-view Sensor, Ozone Monitoring Instrument, and Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar are combined into a 605-member ensemble, and AERONET data are considered as the observations to be assimilated into this ensemble using the EnKF. The assessment is made by comparing the analysis error variance (that has been constrained by ground-based measurements), with the background error variance (based on satellite data alone). Results show that the total uncertainty is reduced by approximately 27% on average and could reach above 50% over certain places. The uncertainty reduction pattern also has distinct seasonal patterns, corresponding to the spatial distribution of seasonally varying aerosol types, such as dust in the spring for Northern Hemisphere and biomass burning in the fall for Southern Hemisphere. Dust and biomass burning sites have the highest spatial representativeness, rural and oceanic sites can also represent moderate spatial information, whereas the representativeness of urban sites is relatively localized. A spatial score ranging from 1 to 3 is assigned to each AERONET site based on the uncertainty reduction, indicating its representativeness level.
Document ID
20170008816
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Li, Jing (Peking Univ. Beijing, China)
Li, Xichen (Peking Univ. Beijing, China)
Carlson, Barbara E. (NASA Goddard Inst. for Space Studies New York, NY United States)
Kahn, Ralph A. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Lacis, Andrew A. (NASA Goddard Inst. for Space Studies New York, NY United States)
Dubovik, Oleg (Lille Univ. France)
Nakajima, Teruyuki (Tsukuba Space Center Japan)
Date Acquired
September 14, 2017
Publication Date
December 19, 2016
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Volume: 121
Issue: 22
ISSN: 2169-897X
Subject Category
Optics
Geosciences (General)
Report/Patent Number
GSFC-E-DAA-TN46445
Funding Number(s)
CONTRACT_GRANT: NSFC 41530423
CONTRACT_GRANT: NSFC 41575018
Distribution Limits
Public
Copyright
Other
Keywords
aerosol optical depth
satellite retrievals
AERONET