Hourly global cloud property retrievals from DMSP, TIROS, and geostationary EO sensors

The United States Air Force has been operationally producing three-hourly depictions of global cloud cover since 1970. Under a program known as the Cloud Depiction and Forecast System II (CDFS II), the Air Force Weather Agency (AFWA) is replacing its existing cloud analysis model with updated technology. The previous models known as 3DNEPH, and later RTNEPH, analyzed two-channel DMSP and TIROS data to produce gridded cloud cover maps with a nominal resolution of 47 km. Major components of the new system include replacement of existing computer processing hardware; an enhanced multiple-satellite data acquisition system capable of acquiring global data from both DMSP and NOAA/TIROS polar-orbiting satellites as well as the international constellation of geostationary environmental satellites; a centralized database for management of calibrated radiometric data and derived meteorological products; a single cloud forecast model for short and long term cloud cover forecasts out to ; and a new cloud detection and characterization model known as the CDFS II - NEPH. The cloud model is based on a series of algorithms developed previously under the Support of Environmental Requirements for Cloud Analysis and Archive (SERCAA) program. Separate source-specific cloud-detection algorithms are used to analyze EO imagery data from each of the unique satellite data sources, a cloud layering and typing algorithm based on unsupervised clustering techniques, and an analysis integration algorithm that employs a modified optimal interpolation approach to merge analyzed cloud products produced from the temporally-independent satellite data sources into a single optimal analysis.