Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-03-14 Cooperative journals: 《干旱区地理》
Abstract： Because of its unique geographic location and landform, Aksu Prefecture, located in the midwest of southern Xinjiang, is prone to gale weather when the surface cold air is forceful. For better knowledge of its mechanism, the fine characteristics and its effect system, and dynamic and thermal conditions of the rare gale over the Tianshan Mountains over Aksu Prefecture from August 15th to 18th , 2019 are assessed, based on conventional and intensive detecting, radiosonde observation, and the National Center for Environmental Prediction reanalysis data. The outcomes are as follows. This gale is known as a persistent gale. The blocking high over Eastern Europe has developed to strengthen against the circulation background, and the Central Asia low vortex has been maintained for a long time, with three short waves split and moving east. It is caused by movement energy converted from cold air potential energy when the upper-level jet stream and low-level cold advection work perfectly together. There are three gale waves, all of which are caused by cold air being guided over the Tianshan Mountains by the upper trough. The gale lasted only a few minutes for the first two times, triggered by a short-wave trough. The gale last time lasted for a long time, triggered by the main trough moving east. For the first time, the gale wave was composed of convective thunderstorm winds with instantaneous wind speeds reaching the grade 12. It benefits the strengthening and preservation of the strong vertical motion and secondary circulation caused by the high-level jet, middle-level convergence, and low-level divergence.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-03-13 Cooperative journals: 《干旱区研究》
Abstract： Based on the observation data of daily precipitation and temperature elements in winter from 1978 to 2020 from 17 national meteorological stations, the spatial- temporal variation characteristics of winter snowfall and its relationship with meteorological factors in the economic belt on the north slope of the middle Tianshan Mountains were analyzed by using various statistical methods. The results show that: The regional distribution of snowfall days and snowfall amount is similar, showing the distribution characteristics of‘more urban areas, less mountainous areas’. The decrease of light snow days is the direct reason for the decrease of total snow days, while the significant increase of moderate snow and blizzard is the main reason for the increase of total snowfall. The precipitation process lasting for 1 day is the main snowfall process in winter. With the increase of the duration, the precipitation process decreases significantly, and the precipitation process ≥ 5 days only accounts for 2.8%; In the past 43 years, the climate on the north slope of Tianshan Mountains has shown an obvious warming and humidifying trend. In 1987 and 1994, the amount of snowfall changed from less to more and the average temperature changed from lower to higher; The amount of snowfall is significantly and positively correlated with the annual precipitation, the average minimum temperature in winter, and the number of snowfall days. The greater the annual precipitation, the lower the minimum temperature in winter, and the more snowfall days, the greater the amount of snowfall in winter, and vice versa.
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