Comparison of the Winter Precipitation Products Over the Tibetan Plateau

Abstract

The multi-model results from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) showed obvious wet biases over the Tibetan Plateau (TP) during winter. However, sparse meteorological stations and the limited capacity for getting accurate snowfall may introduce dry biases into the observation and then exaggerate the overestimation of winter precipitation. In order to explore the spatiotemporal variations and reliability of winter precipitation over the TP, we compared five precipitation products, including: ERA-Interim, GLDAS, HAR, TRMM, and the observation provided by China Meteorological Administration (CMA), against a sublimation dataset which is severed as the minimum value of precipitation. The sublimation was estimated by the Kuzmin formula constrained with IMS snow cover product and land surface temperature. The intercomparison reveals that CMA has an obvious underestimation (precipitation is less than the one third of sublimation) over the Qiangtang Plateau where there is no observation site while no underestimation in East TP where dense stations available. For reanalysis and remote sensing data, HAR shows the smallest underestimation, while TRMM and GLDAS shows comparable underestimation and both are more apparent than ERA-interim. It implies that the observation data has considerable dry biases (~200%) in winter precipitation over the Western TP where more ground stations are needed to get a reliable precipitation observation.