Monday, 10 February 2003
Estimating the error in cloud amount and cloud optical depth retrievals from GOES data
The recently developed Visible-Infrared-Solar infrared-split window technique (VISST), which uses Geostationary Operational Environmental Satellite (GOES) 30 minutes data images, provides retrievals of various cloud properties (Minnis at al, 2001). We juxtapose the VISST derived cloud amount and cloud optical depth with cloud amount and optical depth from independent retrieval techniques using ground-based measurements from Total Sky Imager, Solar Infrared Radiation Station and Multifilter Rotating Shadowband Radiometer. A one-year dataset has been analyzed. Preliminary results show that cloud amount disagreement is up to 10%. We elaborate on the cloud optical depth retrieval agreement with relation to the corresponding values of cloud amount, cloud height, multi-layer cloud presence and solar zenith angle. It is hoped that this study will improve the interpretation of GOES-VISST derived cloud fraction and optical depth, hence the algorithm could be used further for retrievals over ocean where similar inter-comparisons are not possible.