秦岭区域性高山积雪事件变化特征分析

为了研究秦岭高山积雪事件变化特点，利用秦岭陕西境内32个国家气象站1980—2016年度共37年高山积雪观测记录，统计分析5个或者5个以上气象站连续积雪日数≥3 d的区域性高山积雪事件、5个或者5个以上气象站连续积雪日数≥20 d的区域性长时间高山积雪事件、5个或者5个以上气象站连续积雪日数≥60 d的区域性稳定高山积雪事件，结果表明：秦岭1980—2016年度共出现区域性高山积雪事件114次，其中包含区域性长时间高山积雪事件29次，区域性稳定高山积雪事件6次。区域性高山积雪事件均发生在冷季（11月—次年4月），其中60%的区域性高山积雪事件发生在冬季（12月—次年2月）。6次区域性稳定高山积雪事件都发生在12月—次年3月。区域性高山积雪事件1980—1989年度最多（44次），其次是1990—1999年度和2000—2009年度（各29次），2010—2016年度最少（12次）。1980—2016年度，区域性高山积雪事件呈现明显减少趋势（通过α=0.01的信度检验），减幅为-0.86次?（10a）^-1，区域性高山稳定积雪事件次数与冷季平均气温呈显著的负相关关系（通过α=0.01的信度检验）。

Analysis on the variation characteristics of regional alpine snow cover events in the Qinling Mountains

Using a total of 37 a high mountain snow observation data from 32 national meteorological stations in the Qinling Mountains in Shaanxi Province from 1980 through 2016， statistical analysis has been done of the regional alpine snow cover processes with 5 or more consecutive days with snow cover more than or equal to 3 days. The regional stable alpine snow cover processes of long-term alpine snow cover process with 5 or more weather stations with continuous snow cover days greater than or equal to 20 days， 5 or more weather stations with continuous snow cover days greater than or equal to 60 days， have been studied also. The results show that in the Qinling Mountains from 1980 through 2016 there were 114 regional alpine snow cover events， including 29 regional long-term alpine snow cover events and 6 regional stable alpine snow cover events. Regional alpine snow cover events occurred from November to April （the cold season）， among them 60% occurring in winter （December to February）. There were 6 regional stable snow cover events with an average of 73.7 days per snow cover event. The longest regional stable snow cover event， totally lasting 81 days， occurred from November 7， 2003 to April 18， 2004. The number of regional alpine snow events was the highest in the 1980—1989 （44 times）， followed by 1990—1999 and 2000—2009 （29 times each）， and the least one in 2010—2016 （12 times）. The average temperature and precipitation in winter had significantly correlated with the atmospheric circulation index， and had significantly negatively correlated with the Tibetan Plateau Index， the Indo-Burma Basin Intensity Index， the Antarctic Oscillation Index and the Western Pacific Subtropical High West Point Index. Beside， they had clearly positively correlated with the Pacific Trade Wind Index and the Asian Polar Vortex Area Index. In the context of climate warming， the regional snow cover events in the Qinling Mountains had showed a significant reduction trend in 1980—2016， with a reduction rate of -0.8 times/10a. The average number of long-term incidents in various epochs was once a year in the 1980s， 0.9 times a year in the 1990s and only 0.4 times per year in the 1910s. After 2004， there was no regional stable mountain snow cover event in the Qinling Mountains. In 1980—2016， there were 161 snow events in Taibai Station， including 58 long-term snow cover events and 37 snow-stabilizing events. At the 37 a， the regional alpine snow cover events at Taibai Station had showed a decreasing trend with a reduction rate of -0.47 times per 10 years.