Numerical Simulation Of The Influence Of The Surface Temperature Of The Qinghai-Tibet Plateau On The Plateau Vortex

Plateau vortex is a unique weather system in the Tibet Plateau.The occurrence,development and extinction of the plateau vortex are closely related to the changes of the surrounding ground and atmospheric heating fields.The surface temperature is an important factor to measure the surface heating field,and the change of surface temperature in the Tibetan Plateau must have an important influence on the occurrence and development of the vortex.The main research content of this article is as follows:(1)Using the linear trend estimation,wavelet analysis and empirical orthogonal decomposition methods to study the annual average and each of the Tibet Plateau from 1981 to 2015 Seasonal spatial and temporal characteristics of the ERA-Interim skin temperature monthly reanalysis data(resolution 0.5°×0.5°).The results show that the overall temperature of the Tibetan Plateau is lower than the surrounding temperature,and the temperature distribution is mainly affected by the terrain and latitude.The temperature decreases with increasing altitude and decreases with increasing latitude.The high-value center is located in the Qaidam Basin in the northeast of the plateau.In the south of the plateau and in the southeastern part of the Tibetan Plateau,low-value centers are located on the Pamirs and Kunlun Mountains in the northwestern plateau.The annual average temperature of the Tibet Plateau and the surface temperature of each season have been increasing year by year.The warming rate is the fastest in spring,followed by summer and autumn,and the slowest in winter.The warming trends in different seasons are also different.There is a quasi-four-year cycle of changes in the surface temperature of the plateau.The surface temperature in most areas of the plateau is increasing at a temperature increase rate of 0.2°C/10 a.The rate of temperature increase in high altitude areas is generally higher than that in low altitude areas.The temperature increase rate in Ali area reaches 0.6°C/10 a,and the Pamirs and Qilian Mountains show a decreasing trend.The maximum cooling rate is 0.6°C/10 a.The distribution of warming trends in the four seasons was not consistent,and the warming trend in the winter and spring was significantly higher than that in the summer and autumn.The summer,autumn,winter,and annual mean surface temperature of the Tibetan Plateau are dominated by overall changes.In spring,the reversed change of east and west is more significant,followed by summer.(2)Using the WRF model to conduct a numerical simulation of an eastward plateau vortex from June 9th to 11 st,2015,the WRF model can better simulate the formation,movement path,and 500 hPa of the vortex generation and development stages in the plateau.The circulation in height,the precipitation in the process of plateau vortex(rain belt location and large rainfall center),and the characteristics of the eddy structure of the plateau in the development,maturity,and maturity stages of the plateau vortex.(3)Using the WRF model,six groups of sensitivity tests were conducted to increase and decrease the plateau surface temperature in different degrees on the basis of the original control tests.The changes in surface temperature were analyzed on the eddy movement path,center intensity,and vorticity and precipitation over the plateau.The impact of structural and other aspects,reached the following conclusions: increase in surface temperature,the plateau vortex to slow the eastward movement,the higher the temperature,the slower the eastward movement;the other hand,reduce the surface temperature plateau vortex eastward speed up,the lower the temperature eastward Rapidly,but with the development of the plateau vortex,this effect has gradually weakened.Changing the surface temperature has no significant effect on the intensity of the formation and development of the vortex during the plateau vortex.However,at the plateau vortex maturity,the higher the surface temperature,the longer the eddy plateau vortex maintains and the slower the rate of extinction.Changes in surface temperature in the short term can cause changes in vortex precipitation over the plateau,increase in surface temperature(decrease),increase(decrease)in precipitation over the plateau,increase in temperature(decrease),and increase(decrease)in vortex precipitation over the plateau.The surface temperature increases,the central vortex of the plateau vortex increases,the upward movement strengthens,and the plateau vortex develops.However,when the surface temperature of the plateau increases by more than a certain value,the development of the plateau vortex will be inhibited.On the contrary,the surface temperature will decrease.The central vorticity of the vortex decreases,the upward movement decreases,the development of the plateau vortex is inhibited,and the more the temperature decreases,the stronger the inhibitory effect on the development of the plateau vortex.