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NIA Seminar by Fu-Lung Chang |
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Date: January 5, 2006
Time: 10:30am
Location: NIA, Rm 137
On Satellite-Measured New Information of Cloud Layer Properties and Enhanced Retrievals of Cloud Liquid Water Path and Droplet Effective Radius Profile
Fu-Lung Chang, University of Maryland
Satellite retrievals of cloud properties have faced a major challenge with increasing attention being paid to the cloud vertical structure. While operational satellite algorithms usually assume single-layer cloud for retrieving either the bulk (e.g., cloud optical depth) or cloud-top (e.g. temperature, effective radius) properties, comparisons of the cloud vertical distributions derived from satellites and climate models are difficult. To date, cloud profile observations on regional and global scales are scanty and generally unreliable for the purpose of model validation. This talk will introduce two novel retrieval methods for retrieving 1) the vertical distributions of overlapped cirrus-over-water clouds and single-layer cirrus and water clouds (Chang and Li 2005, JAS); and 2) the vertical trend of water-cloud droplet effective radius and enhanced cloud liquid water path (Chang and Li 2002, 2003, JGR). These methods were applied to MODIS data to generate the first near-global cloud layering product (Chang and Li 2005, J. Climate) and new information on water-cloud droplet effective radius profile. Some new findings were revealed, such as a distinct bi-mode distribution of clouds with much less mid-level clouds and much more low-level clouds than previous thought; and also a spatial correlation between precipitation and larger droplet radius at cloud bottom which may help the detection of raining warm clouds. Comparisons will be made against the current MODIS and ISCCP products.
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