采用4个气象站1961—2018年的沙尘暴监测资料,分析了和田地区沙尘暴频次和持续时间的分布特征和变化趋势,并探讨了沙尘暴长时间变化原因。结果表明：（1） 和田地区年平均沙尘暴日数20.4 d,是我国沙尘暴最多的地区之一。（2） 和田地区在春夏季沙尘暴频次最多,峰值在5月;冬季12月的沙尘暴过程持续时间最长,夏季6月的持续时间最短;持续时间在1~30 min的沙尘暴频率最多。（3） 和田地区24 h都有可能出现沙尘暴,在18:00—23:00出现沙尘暴频次最多,后半夜至上午开始的沙尘暴持续时间最长。（4） 和田地区在16个风向方位都会出现沙尘暴,来自西方路径沙尘暴的风速和频率大（多）于其余路径沙尘暴。（5） 在和田地区,最大风速达3.0 m·s^-1就可能会引发沙尘暴,有87.5%的沙尘暴发生时极大风速未达到大风标准。（6） 近58 a来,和田地区的年沙尘暴日数显著减少,年大风日数和最大风速也显著减少;沙尘暴频次20世纪60年代最多,从90年代开始明显减少,沙尘暴过程持续时间20世纪70—80年代最长,从21世纪00年代开始明显缩短。

Using the sandstorm monitoring data of four weather stations from 1961 to 2018, we have analyzed the temporal distribution characteristics and variation trend of sandstorm frequency and duration in Hotan. We also discuss the causes of long-term variation in sandstorms. Our chief findings reveal that Hotan has one of the highest occurrences of sandstorms in China, at 20.4 days per year. The frequency is highest in spring and summer, and the peak is in May. The sandstorms in December are the longest in duration, and those in June are the shortest. The sandstorms that occur most often are those lasting for 1-30 min. Although sandstorms in Hotan might occur at any time of the day, we found that most appeared between 18:00 and 23:00, and those that occurred in the middle of the midnight to morning lasted the longest. In the Hotan region, sandstorms can appear from 16 different wind directions; the wind speed and frequency of sandstorms coming from the western path are higher than are those from the other paths. And those sandstorms in the study region can be caused by the wind which was at the maximum average speed of 3.0 m·s^-1, and 87.5% of the storms occurred while the wind has not reach the standard. Over the last 58 years, the number of annual sandstorm days, the number of annual gale days, and the annual average maximum wind speed in Hotan have decreased significantly. Sandstorm frequency peaked in the 1960s and has decreased sharply since the 1990s. The durations of the sandstorms in the 1970s-1980s were the longest during the past century; the durations have shortened significantly since the 2000s. The decline in the frequency of sandstorms in Hotan Prefecture is related to the decreasing local gale frequency, the weakening of the daily maximum wind speed, and the improvement of the vegetation cover.