Global application of the Self-Calibrating Multivariate Precipitation Retrieval (SCaMPR)

The Self-Calibrating Multivariate Precipitation Retrieval (SCaMPR) is an algorithm for estimating rainfall from a blend of infrared and microwave data. Microwave estimates of rainfall rate, which are more accurate than infrared-based estimates but available only intermittently, are used to calibrate a rainfall algorithm based on infrared brightness temperatures from geostationary satellites, which allow the estimates to be available on a continual basis. The SCaMPR framework is highly flexible, accepting any available gridded data as input, including satellite radiances, numerical weather model output, and cloud-to-ground lightning data. Discriminant analysis is used to calibrate the identification of raining pixels against the target detection fields, and then the rainfall rates are calibrated against the target rain rates using stepwise forward linear regression. SCaMPR uses target rain rates from a variety of microwave instruments, including the Special Sensor Microwave/Imager (SSM/I) and the Advanced Microwave Sounding Unit (AMSU).

Rainfall rates from SCaMPR have been produced experimentally in real time over the continental United States since November 2004, but coverage has now been extended to the entire globe between 60°N and 60°S, using IR data from the two GOES, Meteosat-5 and -8, and MTSAT. To accomplish this, SCaMPR is calibrated for individual 15-by-15-degree latitude/longitude boxes, with spatial smoothing used to remove boundary effects. SCaMPR is especially suited for a global application, as its flexible framework allows it to take advantages in differences in the availability of data across different parts of the globe (e.g., the 12-channel capability of the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instrument onboard Meteosat-8). Examples of this global product will be shown, along with results from real-time validation for various parts of the globe being performed by members of the World Meteorological Organization (WMO) International Precipitation Working Group (IPWG).