黔南州凝冻气候特征以及异常凝冻年环流特征

Characteristics of freezing climate and circulation in abnormal freezing years in Qiannan

贵州凝冻天气主要以雨凇形式出现,该文利用黔南州1968年12月-2018年3月12日地面观测站资料,分析了50a来出现的雨凇和凝冻天气的空间分布、初始时间、持续时间等方面,同时利用NECP/NCAR的2.5°×2.5°格点的逐日再分析资料,探究了黔南出现特重级凝冻和重级凝冻的500hPa环流特征。结果表明:凝冻天气的频次和持续时间的长短,与其地理位置和地貌特征有明显的关系,尤其瓮安出现的凝冻次数最多、持续时间最长,罗甸、荔波50a来未出现凝冻天气;黔南凝冻平均初日在1月中旬到下旬初,平均终日在1月下旬后期;在区域性凝冻天气环流场分析中,高纬地区的冷高压位置越往南且强度越大,则影响黔南出现区域性凝冻天气可能性越大,尤其在太平洋副高西伸的情况下,凝冻灾害最重。

The frozen weather in Guizhou mainly appears in the form of glaze. Based on the data of 12 ground observatories from December 1968 to March 2018 in Qiannan Prefecture,the spatial distribution,initial time and duration of rainstorm and frozen weather in the past 50 years were analyzed. Meanwhile,500 hPa of the daily reanalysis data of 2.5×2.5 grid points of NECP/NCAR were used to explore 50 cases of super-heavy freezing and heavy freezing in Qiannan. The results show that the frequency and duration of frozen weather are obviously related to its geographic location and geomorphological characteristics,especially in Weng'an,where the number and duration of frozen weather are the largest and the longest. No frozen weather has occurred in Luodian and Libo for 50 years. The average beginning date of frozen weather in Qiannan is from mid-January to the beginning of late ten days,and the average end date is in January. In the analysis of regional frozen weather circulation in the late ten days,the higher the location and intensity of cold high in high latitudes,the greater the possibility of regional frozen weather in Qiannan. Especially when the Pacific subtropical high extends westward,the frozen disaster is the most serious.