Vertical and horizontal structure of winter precipitation systems over the western Pacific around Japan using TRMM data

Abstract

The characteristics of winter precipitation systems over the northwestern Pacific are analyzed using data from multiple sensors on board the Tropical Rainfall Measuring Mission (TRMM) satellite. Using the Precipitation Radar (PR) and the Visible Infrared Scanner (VIRS), vertical and horizontal distribution of precipitation is investigated and compared with microwave signatures measured by the TRMM Microwave Imager (TMI). Winter precipitation patterns are classified into four types by the cloud and pressure pattern and the region: the extratropical cyclone and front pattern (CF) and the cold outbreak pattern (CO) over the Sea of Japan (CO-J), over the Yellow Sea (CO-Y), and over the Pacific Ocean (CO-P). For CO the height of precipitation is centered around 2 km and shallow, isolated, and weak (∼20 dBZ) precipitation dominates. Cloud top height reaches about 4 km. Compared with CO-Y and CO-J, CO-P tends to develop larger systems and to have melting layers near the surface. For CF the height of precipitation is concentrated around 3 km and precipitation is relatively broad with a large variation of intensity. These characteristics explain the differences between the retrieved rain rate by PR and TMI. TMI frequently misses precipitation for CO because the systems are usually shallow but less frequently misses weak precipitation than PR for CF because of emission from 85 GHz channel. When both PR and TMI detect rain, the PR rain rate is larger than TMI for CO and smaller than TMI for weak precipitation for CF. From the microwave signature for each pattern it was suggested that the size of precipitation system is one of the possible cause of the differences of rain estimation and detection. Copyright 2006 by the American Geophysical Union.