Comparison of TRMM radar rainfall estimates with NOAA next-generation QPE

Abstract

Rainfall rate fields based on TRMM spaceborne radar observations are compared to those based on the new NOAA Next-Generation Quantitative Precipitation Estimation (QPE) high-resolution national mosaic product (Q2). These rainfall fields can be considered as radar products with the largest coverage currently available from space and ground-based radar observations. They probably can also be considered as the most advanced radar rainfall rate products covering a large area. How well do these two products agree? While the accumulated rain rates from all overpasses combined differ by less than 10%, a comparison between the satellite and ground radar probability distribution functions (pdfs) of the instantaneous rain rate shows very large discrepancies. In general, systematic anomalies over the continental U.S. in TRMM radar pdfs compared to the ground-radar pdfs can be recognized. The pdfs of the TRMM radar are generally shifted towards lower rain rates. Moreover, double peaks occur more frequently in the Q2 than in the TRMM radar pdf. Initial results from the comparisons between these two advanced products are presented. © 2009, Meteorological Society of Japan.