本文利用伊犁河谷国家基本站和区域自动站2015年至2021年5至10月小时降水资料及伊宁新一代多普勒天气雷达资料,采用常规统计方法对伊犁河谷短时强降水天气时空分布及雷达回波参数值进行了研究分析。结果表明:(1) 伊犁河谷短时强降水空间分布呈山区多,平原少的特点,霍城县北部、伊宁县北部、尼勒克县、昭苏县、特克斯县及新源县东部等地的山区大部为显著的高发区并都处于山前的迎风坡处;(2) 近7a中,短时强降水年发生频次整体呈减少趋势,年平均为20次,2016年出现最多,2020年为最少年份;(3) 短时强降水有明显的月变化,自5月迅速增加,6月达到峰值,8月开始减少,6月至7月最为活跃;(4) 短时强降水的日变化呈单峰型结构,峰值出现时段在18~23时;河谷不同地区的日变化特征也不尽相同,西部、东部呈单峰型结构,而南部呈双峰型结构;(5) 当雷达回波参数值中最大回波强度 > 47 dBZ,垂直积分液态水含量 > 10.8 kg/m2,回波顶高 37.2 km2时,伊犁河谷易发生短时强降水天气。This study analyzes the spatio-temporal distribution and radar echo parameters of short-time heavy precipitation in the Yili River Valley using hourly precipitation data from national basic stations and regional automatic stations in the valley, as well as Doppler weather radar data from Yining, Xinjiang, for the period from May to October between 2015 and 2021. The analysis employs conventional statistical methods. The results indicate that: (1) The spatial distribution of short-time heavy precipitation in the Yili River Valley is characterized by a higher frequency in mountainous areas and a lower frequency in plains. Most of the mountainous regions in the north of Huocheng County, the north of Yining County, Nilka County, Zhaosu County, Tekes County, and the east of Xinyuan County are significant high-incidence areas and are located on the windward slopes of the mountains. (2) Over the past seven years, the annual frequency of short-time heavy precipitation has shown an overall decreasing trend, with an average of 20 events per year. The highest frequency occurred in 2016, while the lowest was in 2020. (3) Short-time heavy precipitation exhibits a clear monthly variation, increasing rapidly from May, peaking in June, and decreasing from August, with the most active period being from June to July. (4) The diurnal variation of short-time heavy precipitation follows an unimodal pattern, with the peak occurring between 18:00 and 23:00. The diurnal variation characteristics also vary among different regions of the valley, with
本文利用常规实况观测资料和ERA5 0.25˚ × 0.25˚再分析资料,通过天气学原理和天气动力学诊断分析等方法对2022年11月26~29日昌吉州特强寒潮天气进行诊断分析。结果表明:此次寒潮天气具有历时长、范围广、降温幅度大、低温极端性显著、灾害性天气种类多等特点,出现在乌拉尔山高压脊发展后向东南衰退,引导西西伯利亚强冷空气南下东移的大尺度环流背景下;进入昌吉州的850 hPa冷空气中心达−32℃,冷高压沿西北路径侵入;强冷平流是造成本次寒潮剧烈降温的主要原因;强风的形成与冷平流和强烈的变压梯度有关。降水强盛时期,200 hPa天山南侧出现西风急流、300~500 hPa北疆西边境线风切变线(冷式风切变)、500 hPa槽前偏西气流转为西南急流、700 hPa中上游的塔城和克拉玛依站存在弱的风切变,加之有充分的水汽输送(中低层为水汽的辐合,高层为水汽的辐散)和动力条件(散度和垂直速度),这种高低空的配置为此次寒潮天气提供了必要条件。In this paper, using the actual observation data and ERA5 0.25˚ × 0.25˚ reanalysis data, through methods such as synoptic principles and synoptic-dynamic diagnostic analysis, the extremely severe cold wave weather in Changji Prefecture from November 26 to 29, 2022 was diagnostically analyzed. The results show that this cold wave weather had the characteristics of a long duration, a wide range, a large temperature drop range, significant extreme low temperature, and multiple types of disastrous weather. It occurred under the large-scale circulation background where the high-pressure ridge over the Ural Mountains developed and then declined to the southeast, guiding the strong cold air from West Siberia to move southward and then eastward. The cold air center entering Changji Prefecture reached −32˚C at 850 hPa, and the cold high pressure invaded Changji Prefecture along the northwest path. The strong cold advection was the main reason for the sharp temperature drop during this cold wave. The formation of strong winds was related to cold advection and intense pressure change gradients. During the strong precipitation period, a westerly jet stream appeared on the south side of the Tianshan Mountains at 200 hPa, a wind shear line (cold wind shear) was present along the western border of northern Xinjiang at 300~500 hPa, the westerly air flow in front of the trough at 500 hPa turned into a southwest jet stream, and there was a weak wind shear at Tacheng and Karamay stations in the middle and upper reaches at 700 hPa. Coupled with sufficient water vapor tr
暂无评论