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Proceedings Paper

Examination of scale-dependent physical and radiative properties of clouds using satellite observations
Author(s): Guang Jun Zhang
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Paper Abstract

The satellite data for June-July 1997 at the Southern Great Plains site of the Atmospheric Radiation Measurement program are analyzed. The observed clouds are classified into high, midlevel and low clouds according to their top heights. For each cloud type, the contribution to the total fractional cloud cover from clouds of different sizes is determined using a Lagrangian cloud classification scheme. It is found that in the midlatitude continental, convectively active environment, more than half of the total cloud cover is from high clouds, of which 80% comes from clouds with area > 4 × 104 km2. For midlevel clouds, more than 50% of the contribution to cloud cover is from small clouds (e.g. cloud area < 4 x 104km2).. Almost all of the low clouds with significant contribution to cloud cover have spatial scales <4 × 104km2. This suggests that most of the midlevel and low clouds are of subgrid scale to a typical GCM resolution. We further found that cloud radiative properties, such as cloud albedo, outgoing longwave radiation and cloud radiative forcing, have strong scale dependence. Bigger clouds are brighter and have lower OLR. These results indicate that contributions to the observed cloud radiative forcing are dominated by large cloud systems.

Paper Details

Date Published: 14 April 2003
PDF: 8 pages
Proc. SPIE 4899, Atmospheric and Oceanic Processes, Dynamics, and Climate Change, (14 April 2003); doi: 10.1117/12.466352
Show Author Affiliations
Guang Jun Zhang, Scripps Institution of Oceanography (United States)

Published in SPIE Proceedings Vol. 4899:
Atmospheric and Oceanic Processes, Dynamics, and Climate Change
Zhaobo Sun; Fei-Fei Jin; Toshiki Iwasaki, Editor(s)

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