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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 108, NO. D23,
8657,
doi:10.1029/2003JD003580,
2003
Geostationary satellite retrievals of aerosol optical thickness during ACE-Asia
Jun Wang
Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama, USA
Sundar A. Christopher
Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama, USA
Fred Brechtel
Brechtel Manufacturing Inc., Hayward, California, USA
Jiyoung Kim
Meteorological Research Institute, Seoul, South Korea
Beat Schmid
Bay Area Environmental Research Institute, Sonoma, California, USA
Jens Redemann
Bay Area Environmental Research Institute, Sonoma, California, USA
Philip B. Russell
NASA Ames Research Center, Moffett Field, California, USA
Patricia Quinn
Pacific Marine Environmental Laboratory, NOAA, Seattle, Washington, USA
Brent N. Holben
Biospheric Sciences Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
Abstract
Using 30 days of hourly geostationary satellite (GMS5 imager) data and discrete ordinate radiative transfer (DISORT) calculations,
aerosol optical thickness (AOT) at 0.67 μm was retrieved over the west Pacific Ocean (20°N–45°N, 110°E–150°E) during the Aerosol
Characterization Experiment (ACE-Asia) intensive observation period in April 2001. Different from previous one-channel retrieval
algorithms, we have developed a strategy that utilizes in situ and ground measurements to characterize aerosol properties
that vary both in space and time. Using Mie calculations and bilognormal size distribution parameters inferred from measurements,
the relationship between Ångström exponent (α) and the ratio of two volume lognormal modes (γ) was obtained. On the basis
of spectral AOT values inferred from the Aerosol Robotic Network (AERONET) sites, NASA Ames Airborne Sun photometers (AATS6
and AATS14) and a Sun photometer on board a ship, a successive correction method (SCM) was used to infer the spatial distribution
of α in the study area. Comparisons between the satellite-retrieved AOT and AERONET values over four sites show good agreement
with linear coefficients (R) of 0.86, 0.85, 0.86, and 0.87. The satellite-derived AOTs are also in good agreement with aircraft
(R = 0.87) and ship measurements (R = 0.98). The average uncertainty in our AOT retrievals is about 0.08 with a maximum value
of 0.15 mainly due to the assumptions in calibration (±0.05), surface reflectance (±0.01–±0.03), imaginary part of refractive
index (±0.05), and SCM-derived α values (±0.02). The monthly mean AOT spatial distribution from GMS5 retrievals in April 2001
clearly shows the transport pattern of aerosols with high AOT near the coast of east Asia and low AOT over the open ocean.
Using high temporal resolution satellite data, this paper demonstrates that the diurnal variation in AOT can be retrieved
by current generations of geostationary satellites. The next generation of geostationary satellites with better spectral,
spatial and radiometric resolution will significantly improve our ability to monitor aerosols and quantify their effects on
regional climate.
Received 27
February
2003;
accepted 13
May
2003;
published 30
August
2003.
Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 3360 Meteorology and Atmospheric Dynamics: Remote sensing; 4801 Oceanography: Biological and Chemical: Aerosols (0305).
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Citation: Wang, J., S. A. Christopher, F. Brechtel, J. Kim, B. Schmid, J. Redemann, P. B. Russell, P. Quinn, and B. N. Holben
(2003),
Geostationary satellite retrievals of aerosol optical thickness during ACE-Asia,
J. Geophys. Res.,
108(D23),
8657,
doi:10.1029/2003JD003580.
Copyright 2003 by the American Geophysical Union.
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