Characteristics of extreme precipitation and related near surface atmospheric conditions in summer over the Tibetan Plateau from GPM observations and multi-source reanalysis datasets

This study aims to investigate the characteristics of extreme precipitation and related near surface atmospheric conditions in the summer (June–August) of 2014–2019 over the Tibetan Plateau (26°N-38°N, 78°E-100°E) by using GPM satellite observations and multi-source reanalysis datasets (ERA5, ERA-Interim and CFSv2). Results show that there are notable regional differences in spatial distribution and peak time of extreme precipitation over the Tibetan Plateau. The frequency and intensity of extreme precipitation over the main body of the Tibetan Plateau are smaller than those in the south slope of the Himalayas, whereas the storm top height over the main body of the Tibetan Plateau is higher than that in the south slope. Besides, the storm top height of intense extreme precipitation can reach 17 km. The peak time of extreme precipitation over the Tibetan Plateau mostly occur in the afternoon and midnight. Further analysis reveals that near surface temperatures corresponding to extreme precipitation over the main body of the Tibetan Plateau and the south slope of the Himalayas are approximately 285–290 K and 295–300 K (11.85 °C–16.85 °C and 21.85 °C–26.85 °C) respectively, while surface pressures (specific humidity) are 550 hPa (10 g/kg) and 950 hPa (18 g/kg). The above conditions respectively are most favorable conditions for the occurrence of extreme precipitation in two regions. Moreover, near surface precipitation intensity could be intense under appropriate temperature, pressure and sufficient specific humidity even if CAPE is not large over the Tibetan Plateau. The anomalies of near surface atmospheric conditions related to extreme precipitation exhibit significantly abrupt changes within 6 h before and after the occurrence of extreme precipitation. These results indicate that the spatiotemporal distribution of extreme precipitation based on the GPM observations and the related near surface atmospheric conditions could be considered into forecast of extreme precipitation over the Tibetan Plateau in the future.