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Detecting Thin Cirrus in Multiangle Imaging Spectroradiometer Aerosol RetrievalsThin cirrus clouds (optical depth (OD) < 03) are often undetected by standard cloud masking in satellite aerosol retrieval algorithms. However, the Mu]tiangle Imaging Spectroradiometer (MISR) aerosol retrieval has the potential to discriminate between the scattering phase functions of cirrus and aerosols, thus separating these components. Theoretical tests show that MISR is sensitive to cirrus OD within Max{0.05 1 20%l, similar to MISR's sensitivity to aerosol OD, and MISR can distinguish between small and large crystals, even at low latitudes, where the range of scattering angles observed by MISR is smallest. Including just two cirrus components in the aerosol retrieval algorithm would capture typical MISR sensitivity to the natural range of cinus properties; in situations where cirrus is present but the retrieval comparison space lacks these components, the retrieval tends to underestimate OD. Generally, MISR can also distinguish between cirrus and common aerosol types when the proper cirrus and aerosol optical models are included in the retrieval comparison space and total column OD is >-0.2. However, in some cases, especially at low latitudes, cirrus can be mistaken for some combinations of dust and large nonabsorbing spherical aerosols, raising a caution about retrievals in dusty marine regions when cirrus is present. Comparisons of MISR with lidar and Aerosol Robotic Network show good agreement in a majority of the cases, but situations where cirrus clouds have optical depths >0.15 and are horizontally inhomogeneous on spatial scales shorter than 50 km pose difficulties for cirrus retrieval using the MISR standard aerosol algorithm..
Document ID
20110007811
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Pierce, Jeffrey R.
(Dalhousie Univ. Halifax, Nova Scotia, Canada)
Kahn, Ralph A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Davis, Matt R.
(Science Systems and Applications, Inc. Lanham, MD, United States)
Comstock, Jennifer M.
(Pacific Northwest National Lab. Richland, WA, United States)
Date Acquired
August 25, 2013
Publication Date
April 1, 2010
Publication Information
Publication: Journal of Geophysical Research - Atmospheres
Publisher: American Geophysical Union
Volume: 115
ISSN: 0148-0227
Subject Category
Geophysics
Distribution Limits
Public
Copyright
Other

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