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Constraining Black Carbon Aerosol over Asia using OMI Aerosol Absorption Optical Depth and the Adjoint of GEOS-ChemAccurate estimates of the emissions and distribution of black carbon (BC) in the region referred to here as Southeastern Asia (70degE-l50degE, 11degS-55degN) are critical to studies of the atmospheric environment and climate change. Analysis of modeled BC concentrations compared to in situ observations indicates levels are underestimated over most of Southeast Asia when using any of four different emission inventories. We thus attempt to reduce uncertainties in BC emissions and improve BC model simulations by developing top-down, spatially resolved, estimates of BC emissions through assimilation of OMI observations of aerosol absorption optical depth (AAOD) with the GEOS-Chem model and its adjoint for April and October of 2006. Overwhelming enhancements, up to 500%, in anthropogenic BC emissions are shown after optimization over broad areas of Southeast Asia in April. In October, the optimization of anthropogenic emissions yields a slight reduction (1-5%) over India and parts of southern China, while emissions increase by 10-50% over eastern China. Observational data from in situ measurements and AERONET observations are used to evaluate the BC inversions and assess the bias between OMI and AERONET AAOD. Low biases in BC concentrations are improved or corrected in most eastern and central sites over China after optimization, while the constrained model still underestimates concentrations in Indian sites in both April and October, possibly as a. consequence of low prior emissions. Model resolution errors may contribute up to a factor of 2.5 to the underestimate of surface BC concentrations over northern India. We also compare the optimized results using different anthropogenic emission inventories and discuss the sensitivity of top-down constraints on anthropogenic emissions with respect to biomass burning emissions. In addition, the impacts of brown carbon, the formulation of the observation operator, and different a priori constraints on the optimization are investigated. Overall, despite these limitations and uncertainties, using OMI AAOD to constrain BC sources improves model representation of BC distributions, particularly over China.
Document ID
20150019875
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Zhang, Li
(Colorado Univ. Boulder, CO, United States)
Henze, David K.
(Colorado Univ. Boulder, CO, United States)
Grell, Georg A.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Carmichael. Gregory R.
(Iowa Univ. Iowa City, IA, United States)
Bousserez, Nicolas
(Colorado Univ. Boulder, CO, United States)
Zhang, Qiang
(Tsinghua Univ. Bejing, China)
Torres, Omar
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Ahn, Changwoo
(Science Systems and Applications, Inc. Lanham, MD, United States)
Lu, Zifeng
(Argonne National Lab. IL, United States)
Cao, Junji
(Academia Sinica Beijing, China)
Mao, Yuhao
(California Univ. Los Angeles, CA, United States)
Date Acquired
October 29, 2015
Publication Date
September 1, 2015
Publication Information
Publication: Atmospheric Chemistry and Physics
Publisher: Atmospheric Chemistry and Physics
Subject Category
Environment Pollution
Report/Patent Number
GSFC-E-DAA-TN26813
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Aerosols
Satellite Retrieval
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