基于轨迹模型的和田绿洲沙尘移动轨迹及气象特征分析

以塔克拉玛干沙漠南缘的和田绿洲为研究区域，使用HYSPLIT后向轨迹模型和NCEP的GDAS全球气象要素数据，将和田绿洲西北部的墨玉县城作为模拟受点(79.72°E，37.26°N)，对2004—2018年墨玉县发生的2 891次沙尘天气进行36 h的后向轨迹模拟，并通过k-means聚类分析法，定量分析沙尘天气期间气流的传输路径及气象特征。结果表明：2004—2018年，研究区沙尘天气的发生频率变化幅度不大，没有明显的增减趋势；年内沙尘天气主要集中在春季和夏季（3—7月），占全年沙尘天气总数的70.23%，5、6月是强沙尘暴最活跃期。在沙尘天气期间气流的移动高度和轨迹相差较大，按照气流的起源地和到达墨玉县的方向将沙尘暴分为NW-W簇、N-N簇、NE-E簇和E-ES簇4簇轨迹类型，其发生天数占比分别为18.9%、12.3%、60.1%和7.8%。由东向西的沙尘天气发生天数占比最高（60.1%），但主要以浮尘天气为主；由西北向东南方向的沙尘发生频率不高，但移动速度最快，强沙尘暴和扬沙主要来自西北和西部方向；由北向南的沙尘暴速度最慢（1.36 m/s），空气湿度最低（26.4%），但气温最高（292.58 K）。定量印证了墨玉县沙尘暴不同传输路径，可为绿洲区沙尘暴研究提供参考。

Analysis of the origin and meteorological characteristics of dust-storm in Hetian Oasis based on a trajectory model approach

Hetian oasis located at the south edge of Taklimakan Desert was selected as the study area, and the 36 h of the backward trajectory of air parcel at the ending point (79.72°E, 37.26°N) for 2891 dusty days in the period of 2004-2018 were simulated by using HYSPLIT backward trajectory model and NCEP-GDAS global meteorological data. The transport pathway and meteorological characteristics of air parcel in dusty days were quantitatively analyzed by using k-means clustering technique. The results showed that there was no significant variation in the annual frequency of dust storms from 2004 to 2018, and there was no obvious increase or decrease trend. Spring and summer (from March to July) were the main dusty seasons, accounting for 70.2% of the total dust weather in the whole year, with May and June being the most active periods of strong dust storms. During the dust weather, the movement height and trajectory pathway of air parcel were quite different. The trajectories of dust storms arriving at Moyu County were categorized by k-means clustering into 4 clusters, NW-W cluster, N-N cluster, NE-E cluster and E-ES cluster, which showed distinct features in terms of the air parcel origins and the entry direction to the study site, and their frequencies were 18.9%, 12.3%, 60.1% and 7.8%, respectively. Among them, air masses arriving at the study area from east to west showed the highest frequency (60.1%), and it was mainly floating dust weather. The frequency of dust from northwest to southeast was not high, but the moving speed was the fastest, and strong dust storms and sand blowing mainly came from northwest and west. The dust storms from north to south had the slowest speed (1.36 m/s), the lowest air humidity (26.4%), and the highest temperature (292.58 K). The different transport pathways of dust storms in Moyu County were quantitatively confirmed, which could provide a reference for the study of dust storms in the oasis area.