Instantaneous cloud overlap statistics in the tropical area revealed by ICESat/GLAS data

• Published in: Geophysical research letters Vol. 33; no. 15; pp. L15804 - n/a
• Main Authors: Wang, Likun, Dessler, Andrew E.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.08.2006; Blackwell Publishing Ltd
• Subjects: Atmosphere; Atmospheric Composition and Structure; Cloud physics and chemistry; Earth sciences; Earth system modeling; Earth, ocean, space; Exact sciences and technology; Global Change; Instruments and techniques; Regional climate change; convection; laser methods; attenuation; Cirrus; boundary layer; Height; Climate models; Ice cloud; statistics
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2005GL024350

This study uses ICESat/GLAS instantaneous observations from 29 September to 18 November 2003 to investigate cloud overlap statistics between 10°S–20°N. The results show that 75.1% of profiles detect clouds: 46.5% are single layer and 28.6% multilayer clouds (cloud layers are separated by 0.5km). Using a definition of cloud type based on cloud heights and laser attenuation information, cloud overlap statistics are derived by analyzing 96.4% of the cloudy profiles. The most frequent overlap occurs between cirrus clouds and boundary layer clouds, which accounts for 31.88% of boundary clouds. 23.8% of deep convection has overlying cirrus clouds. We find that differences exist between the cloud overlap fraction from the GLAS observations and one calculated from the random overlap assumption commonly used by climate models.