Characteristics And Causes Of Strong Wind In Tacheng, Xinjiang

The strong wind disasters in Xinjiang area are serious to the lives and production of local residents,which often cause traffic accidents and cause casualties.The paper uses the ground-based measured data of 11 meteorological stations in the Tacheng area(1991-2016),the National Environmental Prediction Center(NCEP)and the relevant data of the National Climate Center to analyze the characteristics of windy weather in the Tacheng area of Xinjiang.The analysis summarizes the causes of the common types of winds in the Tacheng area,and diagnoses the causes of typical windy weather in the Tacheng area of Xinjiang.The main conclusions are as follows:(1)The number of windy days in the Tacheng area is characterized by more north than the south.The middle part of the area from northeast to southwest is an obvious windy and frequent area,surrounded by Tacheng,Laofengkou,Emin and Yumin.The strong wind directions are dominated by the west wind.The number of days and winds in the four seasons is the lowest in autumn and the most in winter.(2)There is a significant decrease in the number of windy days in the Tacheng area(-4.2d/10a).From the 1990 s to the 2000 s,the number of windy days in the Tori area,the Hefeng area,the Wusu area,and the Laofengkou area in the Tacheng area decreased significantly,and the reduction in the number of strong wind days in other areas was relatively small;from the 2000 s to the 2010 s,The reduction in the number of windy days has slowed down noticeably,and the number of windy days in some stations has only slightly decreased.(3)The types of strong winds in the Tacheng area can be divided into three types: cold air active type wind,high altitude momentum down type type wind,and pressure gradient type strong wind.Among them,the cold air active type wind in the north road is often affected by the direct movement of cold high pressure,which makes this happen.strong wind-like winds are often accompanied by a wide range of cooling weather.The cold wind active winds in the northwestern roads in winter areoften the most frequent periods.The wind speed of the strong winds tends to be large,and it is easy to bring sand and dust weather.The duration after the strong winds is longer than the cold wind active winds in the north road;Most of the high-altitude momentum-down winds in the urban area are not directly generated by the influence of the momentum.In many cases,the high-altitude and low-altitude dynamics work together,and the momentum adjustment of the high-altitude atmosphere becomes such.The root cause of the strong winds,the high-altitude momentum-type winds in the Tacheng area are mostly during the day,and the chances of appearing after the night are significantly less.In addition,the emergence of high-altitude momentum-type winds in the Tacheng area is accompanied by dusty weather,and there is less precipitation weather;in the summer of the Tacheng area,due to the heat in the north of Mongolia,due to its location in the northwestern part of Xinjiang The low pressure and the thermal low pressure in the southeastern part of Xinjiang,in the process of moving these hot and low pressures,it is easy to cause the pressure gradient type strong wind in the Tacheng area.(4)In the typical cold air strong wind process in the Tacheng area,the convergence center existing at high altitude continuously tilts westward with the increase of its height.There is obvious cold advection and sinking in the north direction of the Tacheng area.In the situation,when cold air enters the Tacheng area,the sinking of the high-altitude jet stream directly causes an obvious mass increase in the low-level gas column,and the pressure on the ground pressure field is obvious,which exacerbates the horizontal movement of the ground atmosphere,which also triggers the regional The windy wind;combined with the vertical velocity distribution of the strong wind process,the vertical helicity distribution analysis from the strong wind weather process found that during the process of high winds,there is a significant anti-cyclone sinking phenomenon when the cold air passes,and after the cold air is passed.The same phenomenon of anti-cyclone sinking occurred.(5)Numerical Simulation Study of a Typical strong wind Process in Tacheng Area by WRF ModelFirst of all,the simulation results of the dynamic factors can be found that in the strong winds generated in the Tacheng area,the cold air and the high-altitude momentum are jointly affected,so that the strong wind maximum area gradually decreases from the initial height and continues in the strong wind.During the process,the overall distribution of high-altitude wind speed is highly consistent with thelow-altitude wind speed;the thermal factor simulation is specific to the typical strong wind process in the Tacheng area,and a certain sensible heat flux has appeared before the strong wind It reached its maximum value and has since stabilized in the middle of the strong wind.The ground field of this strong wind is controlled by heat and low pressure,and the existence of thermal factors helps to promote low-level turbulence,which reduces the generation and persistence of pure momentum under the strong wind to a certain extent,which is also the gradual weakening of the wind after the momentum.The important reason.The research results of this paper can provide an important practical basis for improving the prevention ability of windstorm disasters and improving the utilization efficiency of wind energy in Tacheng area.