Monday, 10 February 2003
Development and applications of regional cloud products from the CHANCES global cloud database
CHANCES (Climatological and Historical Analysis of Clouds for Environmental Simulations) is a global, hourly, 5 km resolution, visible and infrared cloud and radiance database formed by merging geostationary and polar orbiting weather satellites. We explore a new cloud detection technique using a time series of infrared and visible radiances without any reliance on dynamic external data. The sensitivity of the cloud detection to thresholds and other assumptions is examined. High-resolution, hourly cloud climatologies are created over the Middle East region for January and July, 2001 from the geostationary satellite data using the new temporal technique. These climatologies are compared to twice-a-day Moderate Resolution Imaging Spectrometer (MODIS) results for the same time period. The high temporal resolution climatologies capture many characteristic features of the regional cloud occurrence. Preferred regions for cloud occurrence are documented and explored with both datasets. Topographic effects and land cover variability are major factors in forcing cloud occurrence in this region. Related regional dynamics is also discussed.