Incorporating relative humidity improves the accuracy of precipitation phase discrimination in High Mountain Asia

Precipitation is an important link in the global water cycle, with changes in precipitation phase patterns significantly affecting the water and energy balance. Precipitation types in the High Mountain Asia (HMA) have changed with global warming, and precise identification of precipitation types is a primary prerequisite for conducting studies such as future snowfall changes. In this study, five precipitation phase discrimination methods, namely, Ta, Dai, Td, Ding and Trh, were compared and analyzed in the process of precipitation phase identification in HMA using daily meteorological observation data from 1951 to 2020.The results show that better accuracy is exhibited by Td, Ding and Trh, which combine relative humidity, Ta or Dai methods, which only consider temperature. Among them, the Ding method has the highest overall accuracy (93.35%), followed by Trh (93.24%), Dai (91.38%) and Td (89.57%). The Ta method produces relatively low accuracy results (89.05%) and underestimates snowfall to some extent. In general, among the various methods, the use of combined relative humidity and air temperature allows for better discrimination of precipitation phase, which provides an important scientific significance and guidance for research in the fields of meteorology and hydrological processes.