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Comparison between SAGE II and ISCCP high-level clouds. 1: Global and zonal mean cloud amountsGlobal high-level clouds identified in Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation measurements for January and July in the period 1985 to 1990 are compared with near-nadir-looking observations from the International Satellite Cloud Climatology Project (ISCCP). Global and zonal mean high-level cloud amounts from the two data sets agree very well, if clouds with layer extinction coefficients of less than 0.008/km at 1.02 micrometers wavelength are removed from the SAGE II results and all detected clouds are interpreted to have an average horizontal size of about 75 km along the 200 km transimission path length of the SAGE II observations. The SAGE II results are much more sensitive to variations of assumed cloud size than to variations of detection threshold. The geographical distribution of cloud fractions shows good agreement, but systematic regional differences also indicate that the average cloud size varies somewhat among different climate regimes. The more sensitive SAGE II results show that about one third of all high-level clouds are missed by ISCCP but that these clouds have very low optical thicknesses (less than 0.1 at 0.6 micrometers wavelength). SAGE II sampling error in monthly zonal cloud fraction is shown to produce no bias, to be less than the intraseasonal natural variability, but to be comparable with the natural variability at longer time scales.
Document ID
19950043412
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Liao, Xiaohan
(NASA Goddard Institute for Space Studies, New York, NY United States)
Rossow, William B.
(NASA Goddard Institute for Space Studies, New York, NY United States)
Rind, David
(NASA Goddard Institute for Space Studies, New York, NY United States)
Date Acquired
August 16, 2013
Publication Date
January 20, 1995
Publication Information
Publication: Journal of Geophysical Research
Volume: 100
Issue: D1
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A75011
Distribution Limits
Public
Copyright
Other

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