Comparison of satellite precipitation products with rain gauge data for the khumb region, Nepal Himalayas

Abstract

Rain gauge data for the period of 1998-2004 from the Syangboche Automated Weather Station (S-AWS) site in the Nepal Himalayas were compared with multi-satellite precipitation products for the period of 2003-2005, employing several retrieval algorithms: the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA), the Climate Prediction Center (CPC) morphing algorithm (CMORPH), the Precipitation Estimation from Remote Sensing Information using an artificial neural network (PERSIANN), and the Global Satellite Mapping of Precipitation (GSMaP). All the products, except GSMaP, showed an increase in precipitation during the summer monsoon, in agreement with S-AWS. However, PERSIANN showed large differences with the observed values in winter and CMORPH had a tendency to overestimate precipitation in the pre- and post-monsoon seasons relative to S-AWS/TMPA. Summer monsoon precipitation showed an increase in the evening and mid-night in all products except GSMaP, but the local-time peak in PERSIANN lagged compared to that of S-AWS by several hours, and the peak in other products was ahead of that in S-AWS by several hours. All products except for PERSIANN showed an increase in precipitation during the morning. The differences among the products may reflect microwave signatures from convection, the sun-synchronous satellite orbit, and infrared-merging processes. A verification of rain detection by GSMaP revealed good scores over global land areas except for the Tibetan Plateau (including the present study area) due to insufficient resolution for rain/no-rain classification. The peak local-time distribution of precipitation showed a relationship with the topography in the order of precipitation radar (strongest relationship), microwave radiometer, and infrared products. © 2011, Meteorological Society of Japan.