新疆西部一次大暴雨过程水汽输送轨迹模拟

Simulation of Water Vapor Transport Trajectories of a Heavy Rain in Western Xinjiang

在分析2016年7月28日—8月2日新疆西部罕见大暴雨过程环流形势和影响系统的基础上,利用基于拉格朗日方法的轨迹模式HYSPLIT,应用GDAS资料,模拟计算了大暴雨期间不同区域不同高度的水汽输送轨迹、主要通道及不同源地的水汽贡献。结果表明:(1)200 h Pa高空偏西急流、700 h Pa和850 h Pa低空偏东急流及辐合线和500 h Pa稳定"两脊一槽"环流是大暴雨产生的天气背景;(2)大暴雨过程中阿克苏地区北部、伊犁河谷地区和博州地区东部1500、3000和5000 m水汽输送轨迹、主要通道及不同源地的水汽贡献存在差异,其中,阿克苏地区北部1500、3000、5000 m水汽分别主要来自中亚地区、中亚地区、地中海北部,水汽贡献分别占该高度水汽的38%、46%、48%;伊犁河谷地区1500、3000、5000 m水汽分别主要来自哈萨克斯坦、哈萨克斯坦、黑海南部,水汽贡献分别占该高度水汽的100%、50%、68%;博州地区东部1500、3000、5000 m水汽分别主要来自西西伯利亚、中亚地区、东欧,水汽贡献分别占该高度水汽的58%、54%、82%。水汽在输送过程中高度多变,以偏东和偏南路径为主输送到大暴雨区上空;(3)欧洲大陆、西西伯利亚、中亚地区等陆地及黑海、里海等海洋是此次大暴雨水汽主要来源。南疆低层偏东风和辐合线在水汽的聚集及向上输送中发挥了重要作用,高空急流产生的次级环流的下沉气流在将高空水汽向下输送中扮演了重要角色。

Based on the analysis of the circulation situation and influence system of the rare heavyrain in the west of Xinjiang from July 28th to August 2rd, 2016, the HYSPLIT model based on theLagrangian method was used to calculate the water vapor transport trajectories, the main passagesand different contribution of water vapor sources of the different areas and different heights. Theresults showed that（1）200 hPa high-altitude partial west jet, 700 hPa and 850 hPa low-altitudepartial east jet and convergence line as well as 500 hPa stable “two ridges and one groove”circulation were the synoptic background of the heavy rain. （2）In the process of heavy rain, therewere differences in the water vapor transport trajectory and the contribution of water vapor whichcame from different sources in northern Aksu, the Ili River valley and eastern Bozhou. Water vaporof 1500 m, 3000 m, 5000 m in northern Aksu mainly came from Central Asia, Central Asia,northern Mediterranean respectively, and contribution of water vapor accounted for 38%, 46%, 48%.Water vapor of 1500 m, 3000 m, 5000 m in Ili River valley mainly came from Kazakhstan,Kazakhstan, south of the Black Sea respectively, and contribution of water vapor accounted for100%, 50%, 68%. Water vapor of 1500 m, 3000 m, 5000 m in eastern Bozhou mainly came fromWestern Siberia, Central Asia, Eastern Europe respectively, and contribution of water vaporaccounted for 58%, 54%, 82%. The heights of water vapor passages varied in transportation with theeast and south passages as its main path.（3） Continental Europe, Western Siberia, Central Asia andother lands and the Black Sea, the Caspian Sea and other seas were the main sources of the watervapor. The low-altitude partial east wind and the convergence line played an important role in theaccumulation and upward transportation of water vapor in southern Xinjiang, the sinking airflow ofthe secondary circulation which generated by the high-level jet also havea tremendous impact ondownward convey of high-altitude water vapor. Almost all trajectories have been passed through theCentral Asian region to reach the heavy rain areas, the Central Asian region was hence the keyareas of water vapor passages in the process of heavy rain.