Microphysical Characteristics of Snowfall on the Southeastern Tibetan Plateau

Snowfall on the Tibetan Plateau (TP) is crucially important to the hydrological cycle and glacier acceleration over the TP and surroundings. Climate and weather models are challenged by biases and uncertainties in representing microphysical characteristics of snowfall over TP. In order to bridge the gaps in our understanding of microphysical characteristics of snowfall on the southeastern TP (SETP), an integrated and systematic measurement is conducted at the South-East Tibetan Plateau Station during the two winters of 2022-2023. It is the first time to conduct a long-term measurement of microphysical characteristics of snowfall on the SETP. The major objective of this campaign was to collect cloud microphysical properties including, fall velocity, aspect ratio, and particle size distribution (PSD). The results show that the particle number concentration is less than 10(3) mm(-1)<middle dot>m(-3), which is one to two orders of magnitude smaller than that reported in low-altitudes in eastern China. The shape parameter mu is mainly in the range 0-4, and the slope parameter lambda is mainly in the range 3-7 mm(-1), exceeding the values for eastern China. In heavy snowfall processes (snowfall rate (SR) exceeding 2 mm/hr), the collision-coalescence process between snowfall particles is enhanced, and the number concentration of small particles decreases with SR, whereas that of large particles increases. A negative correlation was observed between the aspect ratio and the diameter of snowfall particles. The microphysical characteristics of snowfall will be used to improve the microphysical scheme and evaluate the representation of precipitation in the climate model.