First evaluation of GPM-Era satellite precipitation products with new observations on the western Tibetan Plateau

Satellite precipitation products can provide alternative data in remote areas with sparse surface observations, but the performance of these products must be evaluated before hydrometeorological applications. The western Tibetan Plateau (WTP) covers an area of nearly 1,500,000 km2, where China Meteorological Administration stations are very sparse due to the harsh natural environment. Therefore, previous evaluations of satellite pre-cipitation products have resulted in a gap on the WTP. In this study, hourly data collected from 29 newly established rain gauges on the WTP were applied to evaluate the performance of four Global Precipitation Measurement (GPM)-Era precipitation products without calibration (IMERG-UC and GSMaP-MVK) and with calibration (IMERG-C and GSMaP-Gauge). The evaluation results for the WTP were compared with those for the eastern Tibetan Plateau (ETP). (1) The effect of the calibration of satellite products highly depends on the temporal resolution of precipitation data used for calibration. The GSMaP-Gauge, which are calibrated with daily data, outperforms the IMERG-C, which are calibrated with monthly data, on both monthly scale and daily scale. (2) The calibration effect of the satellite products is not positive in reproducing the precipitation amount on the WTP due to few observations available for calibration but was notable on the ETP. (3) None of the four satellite precipitation products can reproduce the hourly precipitation frequency-intensity structure well. Both IMERG and GSMaP produce too much light precipitation events on the WTP. In addition, the four products produce too early timing of diurnal precipitation peak on the WTP. The calibration does not improve the timing phase of precipitation amount but affects the intensity of diurnal precipitation peaks on the WTP. These new findings provide important information on the accuracy of the four widely used satellite precipitation products on the WTP and thus can be a solid reference for hydrometeorological applications on the WTP.