Abstract:

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.

Key words: Sandstorm, Duration, Wind velocity threshold