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Extending "Deep Blue" Aerosol Retrieval Coverage to Cases of Absorbing Aerosols Above Clouds: Sensitivity Analysis and First Case StudiesCases of absorbing aerosols above clouds (AACs), such as smoke or mineral dust, are omitted from most routinely processed space-based aerosol optical depth (AOD) data products, including those from the Moderate Resolution Imaging Spectroradiometer (MODIS). This study presents a sensitivity analysis and preliminary algorithm to retrieve above-cloud AOD and liquid cloud optical depth (COD) for AAC cases from MODIS or similar sensors, for incorporation into a future version of the "Deep Blue" AOD data product. Detailed retrieval simulations suggest that these sensors should be able to determine AAC AOD with a typical level of uncertainty approximately 25-50 percent (with lower uncertainties for more strongly absorbing aerosol types) and COD with an uncertainty approximately10-20 percent, if an appropriate aerosol optical model is known beforehand. Errors are larger, particularly if the aerosols are only weakly absorbing, if the aerosol optical properties are not known, and the appropriate model to use must also be retrieved. Actual retrieval errors are also compared to uncertainty envelopes obtained through the optimal estimation (OE) technique; OE-based uncertainties are found to be generally reasonable for COD but larger than actual retrieval errors for AOD, due in part to difficulties in quantifying the degree of spectral correlation of forward model error. The algorithm is also applied to two MODIS scenes (one smoke and one dust) for which near-coincident NASA Ames Airborne Tracking Sun photometer (AATS) data were available to use as a ground truth AOD data source, and found to be in good agreement, demonstrating the validity of the technique with real observations.
Document ID
20160007477
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Sayer, A. M.
(Universities Space Research Association Greenbelt, MD, United States)
Hsu, N. C.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Bettenhausen, C.
(Science Systems and Applications, Inc. Greenbelt, MD, United States)
Lee, J.
(Maryland Univ. Greenbelt, MD, United States)
Redemann, J.
(NASA Ames Research Center Moffett Field, CA, United States)
Schmid, B.
(Pacific Northwest National Lab. Richland, WA, United States)
Shinozuka, Y.
(Bay Area Environmental Research Inst. Moffett Field, CA, United States)
Date Acquired
June 13, 2016
Publication Date
May 7, 2016
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Publisher: American Geophysical Union
Volume: 121
Issue: 9
Subject Category
Earth Resources And Remote Sensing
Geophysics
Meteorology And Climatology
Report/Patent Number
GSFC-E-DAA-TN32329
Funding Number(s)
CONTRACT_GRANT: NNX12AD03A
CONTRACT_GRANT: NNG12HP08C
CONTRACT_GRANT: NNG11HP16A
Distribution Limits
Public
Copyright
Other
Keywords
aerosols above clouds
aerosol retrieval
Deep Blue

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