青海高原降水相态转换特征及预报指标分析
Analysis of Precipitation Phase Transition Characteristics and Prediction Indices in Qinghai Plateau
中文摘要：
基于青海高原50个地面气象观测站点2006—2020年的观测资料，结合ERA-Interim再分析资料，利用线性倾向估计、概率密度分析等方法，揭示青海高原降水相态转换时空分布特征及相态预报指标,并对2021年的观测资料开展检验。结果表明：1）青海高原降水相态转换主要发生在春末夏初及秋季，空间上主要集中在祁连山区及青南地区，这与海拔高度密切相关；2）降水相态与低层温度密切相关,相对于地面的特征温度层（0 ℃、－5 ℃层等）高度、地面2 m温度和特征气压层（500 hPa、600 hPa、700 hPa）的温度可作为相态预报指标；3）雨转雪过程与雪转雨过程预报指标有明显差异，雪转雨时地面到0 ℃层温度垂直递减率大于雨转雪过程；4）检验结果表明，低层及地面2 m温度指标的可用性较好，中高层指标有一定偏差。
中文关键词：
青海高原，降水相态转换，预报指标，温度层结，检验评估
KeyWords：
Qinghai Plateau, precipitation phase transition, prediction indices, temperature stratification, verification
Abstract：
Using the observation data from 50 ground-based meteorological stations in Qinghai Plateau during 2006—2020 and ERA-Interim reanalysis data, the linear tendency estimation and probability density analysis are used to reveal the spatial-temporal distribution characteristics of precipitation phase transition and prediction indices in Qinghai Plateau. Meanwhile, the observation data in 2021 are also verified. The results show that: (1) The spatial-temporal distribution of precipitation phase transition is closely related to altitude. It mainly occurs in late spring, early summer and autumn, concentrated in the Qilian Mountains and Southern Qinghai; (2) Precipitation phase is closely related to the low-level temperature. The height of the characteristic temperature layer (0 ℃ layer, －5 ℃ layer, etc.), which is relative to the ground, T2m and the temperature of the characteristic pressure layer (500 hPa, 600 hPa, 700 hPa) can be used as the phase prediction indices; (3) The prediction indices of rain-to-snow and snow-to-rain are significantly different, and the temperature lapse rate from ground to 0 ℃ layer of snow-to-rain process is greater than that of rain-to-snow process; (4) The verification results show that the temperature indicators at the lower level and T2m exhibit satisfactory applicability, while there is a certain deviation at the middle and higher levels.