基于逐时数据的南疆沙尘天气精细化特征研究

利用2006—2019年南疆地区55个国家站的逐日观测和自动站小时数据资料，研究沙尘发生的精细化特征及沙尘暴起沙风速指标阈值。结果表明：南疆沙尘中心位于塔里木盆地中部至其南缘的民丰和且末一线，表现为中部多，东部西部少的分布特点，浮尘和沙尘暴的中心在民丰，而扬沙中心在塔中站；沙尘天气季节差异明显，秋、冬季沙尘最少，以浮尘为主，春、夏季是沙尘天气的高发季节，浮尘日与扬沙日数接近，约为沙尘暴的2倍，沙尘暴、扬沙的季节差异比浮尘天气更为明显；沙尘日变化呈白天多于夜间，下午多于上午的分布特点，18—20时是南疆地区出现沙尘暴、扬沙天气的高频时段；扬沙和沙尘暴的平均持续时间短，一般不超过3 h，巴州东南部平均持续时间最长；南疆不同地区沙尘天气发生的最小风速差异较大，存在区域性规律，而极大风速分布呈东部大于西部，北部大于南部，塔里木盆地中部和南部最小，春季的极大风速平均值大于夏季，差值较小的地区在和田地区，春季的极大风速离散度也较夏季大，各站极大风速的最小值范围在1.6—9.8 m·s^-1之间。

Characteristics of dust weather in southern Xinjiang based on hourly data

Based on the daily observation and hourly automatic station data at 55 national stations in southern Xinjiang from 2006 to 2019, the fine characteristics of dust weather and the threshold velocity on sandstorms were studied. The results indicate that the sand center in southern Xinjiang was located from the central part to the southern edge of Tarim Basin, showing the higher distributions in the central part whereas lower in the eastern and western part. The center of floating dust and sandstorm was in Minfeng whereas that of blowing sand was in Tazhong station. Dust weather had significant seasonal variation. It appeared lest in autumn and winter with floating dust being the main contributor. Whereas it appeared more in spring and summer with floating dust and blowing sand being the main contributor. Seasonal variations in a sandstorm and blowing sand were more significant than those in floating dust. Dust weather appeared more frequently in the daytime, especially in the afternoon, compared with nighttime, during which sandstorms and blowing sand appeared dominantly from 18:00 to 20:00 over southern Xinjiang. Blowing sand and sandstorm lasted shorter with a duration of less than 3 hours and the longest duration appeared in the southeast of Bazhou. The minimum wind velocity triggering dust varied significantly among various areas of southern Xinjiang, while the maximum wind speed appeared higher in the eastern part than in the western part, and higher in the northern part than in the southern part with the lowest values appeared in the central of Tarim Basin. Mean maximum wind speed was higher in spring than in summer with a lower speed difference appeared in the Hetian area. Moreover, the dispersion of the maximum wind speed was higher in spring as well, with the minimum value at each station varying from 1.6 m·s^-1 to 9.8 m·s^-1.