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.
Subjects: Environmental Sciences, Resource Sciences >> Other Disciplines of Environmental Sciences, Resource Sciences submitted time 2021-03-02 Cooperative journals: 《干旱区研究》
Abstract：中亚地区常规观测站点稀少，需借助星载高光谱AIRS资料分析出该地区数值预报最优初始场。以CRTM中输入探空模拟出的AIRS辐射亮温为参考值，分析了AIRS观测亮温偏差，并评估了AIRS卫星资料在中亚数值天气预报业务系统中的适用性。结果表明：（1）各通道模拟所选站点上空亮温最大正偏差的平均值约为3.3 K，最大负偏差的绝对值约为2.6 K。（2）多个站点平均的AIRS观测辐射亮温整体略高于模拟亮温，其概率密度分布比单个站点更加接近正态分布曲线。（3）AIRS的同化改善了RMAPS-CA对位势高度、温度、比湿等高空要素的预报效果，并未改善高空风速的预报。对各个要素，AIRS的同化改善幅度在低层较高层大。同化后，位势高度、温度、比湿和风速的预报RMSE分别小于20 gpm、2 K、8×10-4 kg·kg-1以及5 m·s-1。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-08-02 Cooperative journals: 《干旱区地理》
Abstract：为了深入了解天山山区中尺度对流系统（MCS）的触发和变化，对发生在新疆伊犁河谷一次中亚低涡背景下的短时强降水过程MCS成因进行了分析。通过利用自动站小时降水数据分析得出此次降水时空分布特征，并基于FY-2G卫星TBB产品、多普勒天气雷达数据对MCS的云图和雷达特征进行分析，得出该地区中-β尺度MCS(MβCS)具有明显的夜发性和后向传播特征，且分别在山区、平原上空发展和增强并长时间维持，雷达图上强回波带、逆风区和超低空急流的持续出现说明局地对流增强。此外，选取代表站雨强与对应TBB、雷达回波进行分析，发现强降水时段雨强的空间分布与TBB梯度大小成正比，时间分布与回波顶高和垂直液态含水量成正比。利用探空、地面风场以及ERA-Interim再分析资料对MCS形成的大尺度环流背景和中尺度特征进行分析，得出深厚中亚低涡前部局地对流活动的加强触发MCS的生成，中低层多通道水汽输送和局地长时间水汽辐合、大气不稳定层结、中低层的风场辐合和垂直切变、高低层θse梯度增大以及低层暖平流增强为MCS的发展和维持提供了动热力和水汽条件。
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