Abstract:

The most obvious feature of measuring climate changes in one or more regions is precipitation, and the magnitude and distribution of precipitation directly restricts the development of the national economy and the bumper harvest of agricultural production, and also closely relates to the lives of the individuals. The Kashi Prefecture, Xinjiang, China is located in the abdomen of Central Asia, and it belongs to the warm temperate continental arid climate zone, with distinct four seasons and sufficient sunshine. Its annual and daily temperature changes are of great disparity, the precipitation is less and the evaporation is strong. Although the overall precipitation in Xinjiang is relatively small, the contribution of extreme precipitation to the total amount of precipitation is still on the rise. Previous research scales for precipitation in Kashi mainly focused on monthly precipitation or diurnal precipitation changes. In the context of global warming, it is particularly important to study the annual variation of precipitation over the whole year, which is not only extremely important for the meteorological services in the designated region, but also plays a vitally important guiding role in artificial flood control and rain enhancement (snow) operations, and even has an important significance for understanding the climate characteristics and trends of Xinjiang. This paper utilizes the hourly precipitation data of 10 meteorological stations in the Kashi Prefecture from January to December 2010 to analyze the daily variation characteristics (from the precipitation, precipitation frequency, precipitation intensity and precipitation over time) of precipitation (rain and snow) in the Kashi Prefecture. The results show as follows: (1) There are obvious fluctuations in the annual variation of precipitation and precipitation frequency in Kashi, and overall it formed a sinusoidal wave shape characterized by one peak and one valley, and the peak of precipitation appears at 03:00 AM (Beijing time, the same below) and the valley at 18:00 PM; the peak frequency of precipitation appears at 04:00 PM and the valley at 18:00 PM. (2) From 2010 to 2017,the annual precipitation and precipitation frequency in the Kashi region showed a significant increase trend; while the annual variation of precipitation intensity tended to be gentle and had no obvious change. (3) There is no consistency between the daily variation trend of precipitation intensity and the frequency of precipitation and the amount of precipitation. (4) The precipitation in the whole year depends mainly on shortperiod precipitation. Among them, most of the precipitations lasted for about 1 hour, and the precipitations with 2 hours duration contributed the most to the amount of precipitation yet the precipitations of 6 hours duration ranked first from the contribution ratio perspective. The precipitation in the Kashi region is mainly dominated by precipitation in the middle of the night and in the morning.

Key words: precipitation (rain and snow), diurnal variation, precipitation frequency, precipitation intensity, Kashi Prefecture