2013年初夏青海北部地区一次罕见低温冻害天气个例分析

利用常规气象资料,对2013年6月10日发生在青海省柴达木盆地东缘及东部湟水谷地的一次强降温冻害天气过程进行了天气学分析,初步探讨了在全球气候变暖的大背景下,青海高原农业气象灾害的新特征。结果表明,(1)此次降温天气过程,是在全球气候变暖背景下的极端天气事件;(2)冷空气影响青海北部时间长达24h,且强度较强,控制时间长;加之晴空辐射降温显著,是造成"610强降温"低温冻害的主要原因。(3)由于前期的晴热少雨天气,使得作物提前进入旺长期,降低了作物承受低温的能力,加之夜间平流降温和晴空辐射降温叠加,增大了地面降温幅度,加剧了冻害程度;(4)在高空有利的形势场配置下,冷空气不断积聚,而后分裂南下,在地面形成强大的冷性高压控制青海省北部地区,并自西向东影响青海北部地区。

Analysis on a Rare Low-temperature and Freeze-injury Weather Process in Early Summer 2013 in the Northern Qinghai

Based on the conventional meteorological data,a diagnostic analysis of cold weather process in the eastern edge of Chaidamu basin in Qinghai Province and in the eastern Huangshui valley on June 10,2013 is given,which preliminarily discusses the new characteristics of agriculture meteorological disasters in Qinghai plateau under global warming. The results showed that it was a extreme weather event,the strong cold air impacted the northern Qinghai has lasted 24 hours,and the distinctive radiation cooling in clear sky was the main reason of this process. The hot and sunny weather in early days accelerates crops entering fast growing period,that weakens the crop＇s ability to low temperature. The advection cooling during the night and radiation cooling in clear sky increase the cooling amplitude on the ground,which intensifies the freezing. The cold air continually accumulates under advantageous weather situation,then divides and moves southward,so the powerfully cold high-pressure is formed on the ground,that impacts the northern Qinghai from west to east.