新疆阿勒泰地区近四十年极端高温时空特征
Spatial and Temporal Characteristics of Extreme High Temperature in Altay Prefecture of Xinjiang in Recent 40 Years

本文利用ERA5再分析数据和NCEP月平均数据对阿勒泰地区最高气温指数的长期气候特征和变化及其天气学影响因子进行系统分析，发现阿勒泰地区夏季最高气温气候态分布呈现南高北低的分布形势，6月和8月最高温度气候态分布类似，整个夏季来说，最高气温超过40℃的地区主要位于阿勒泰地区西南部的准噶尔盆地附近，受天山山脉地形影响显著；最高气温标准差分布上表现为6月和8月最高温度标准差分布类似，7月最高温度变化幅度最大，最高温度变率较大的地区主要位于福海县北部、富蕴县西部偏西地区、阿勒泰市东南部、布尔津县南部、哈巴河县东南部和吉木乃县北部和东部；阿勒泰地区最高气温的年代际变化上，7月最高温度具有明显的年代际振荡变化，尤其在进入21世纪后更加明显。分析阿勒泰地区最高气温环流特征，发现阿勒泰地区发生极端高温天气时，伊朗副高发展东伸北抬，与北支的高压脊同位相叠加，受西太副高影响较小，中高层温度场上具有全国一致性的变化，850 hPa位势高度场上可见西太平洋地区持续向阿勒泰地区输送大量偏暖气流，西伯利亚南部地区和我国西北地区的高值系统对冷空气的东移南下形成了较强的阻挡；850 hPa温度场上同样表现出伊朗高压的影响较为明显，这在低层的垂直速度和比湿场上同样有体现；海平面气压场上表现为全国一致性的正异常，由于高空多为高压系统控制，下沉运动明显，导致地面气压偏低，从而为高温天气的维持提供了较为稳定的环流形势。
In this paper, ERA5 reanalysis data and NCEP monthly average data are used to systematically analyze the long-term climatic characteristics and changes of the highest temperature index in Altay region and its synoptic influencing factors. It is found that the climatic distribution of the highest temperature in summer in Altay region is high in the south and low in the north. The climatic distribution of the highest temperature in June and August is similar. Throughout the summer, the area with the highest temperature exceeding 40？C is mainly located near the Junggar Basin in the southwest of Altay region, which is significantly affected by the topography of the Tianshan Moun-tains. The distribution of the standard deviation of the highest temperature in June and August is similar to that of the highest temperature in June and August. The maximum temperature change in July is the largest. The areas with large maximum temperature variability are mainly located in the northern part of Fuhai County, the western part of Fuyun County, the southeastern part of Altay City, the southern part of Buerjin County, the southeastern part of Habahe County and the northern and eastern parts of Jimunai County. On the interdecadal variation of the maximum temperature in Altay, the maximum temperature in July has obvious interdecadal oscillation changes, especially after entering the 21st century. By analyzing the circulation characteristics of the highest temper-ature in the Altay region, it is found that when the extreme high temperature weather occurs in the Altay region, the Iranian subtropical high develops eastward and northward, and is superimposed in the same phase with the high pressure ridge of the northern branch. It is less affected by the western Pacific subtropical high, and the temperature field in the middle and upper layers has the same change in the whole country. On the 850 hPa geopotential