The Characteristics Of The Temporal And Spatial Evolution Of The South Asian High And Its Influence On The Temperature And Precipitation In Southwest My Country

This paper uses the temperature and precipitation observation data of the National Meteorological Ground Observation Site from 1979 to 2017 and geopotential Height,zonal wind,meridional wind,vertical velocity and specific humidity provided by ERA-Interim.After reanalysing the data,the area index and intensity index of the South Asia high pressure are calculated.The changes of the east ridge point and the main center position are compared and analyzed.The temporal and spatial evolution characteristics and the summer precipitation in southwest China are discussed through comparative analysis and synthetic research.Further,the heat fluxes such as sensible heat,latent heat,net long-wave radiation and net short-wave radiation provided by ERA-Interim were used to analyze the data month by month,and the influence of the South Asian high pressure on the summer temperature in southwest China was discussed through synthetic analysis.The results show that:(1)There are obvious seasonal changes in the various characteristic indexes of SouthAsia High.The indexes began to increase in April,reaching the strongest in Julyand gradually weakening in September.The main center and the eastern ridge pointstretched out in the summer and reached the strongest in July.The east ridge pointhas a trend of eastward movement in recent years.The main center oscillates eastand west,and the strength and area index have a good consistency.The sameincrease and decrease,and there are maximum values in 1998.(2)The establishment of the South Asian high in the plateau occurred mainly inmid-June,and was normal in the third month of June.It was established earlier thanJune 3,and it was late in June.The evacuation occurred in the third day of October,which was normal.It was earlier in October than in the third month of October,andthe third time in October was the late evacuation.Compared with the establishment,the date of the South Asian high-pressure evacuation of the plateau fluctuated more.The strength of the South Asian high-pressure landing and evacuation from theplateau is closely related to the intensity of the South Asian high.When the highpressure is established late on the plateau,the high-pressure strength is affected.When the high pressure is high,the high pressure evacuation of the plateau willalso be affected later.The late login has the greatest impact on the high pressure.When the high pressure is weak,the high pressure evacuation will be earlier.(3)The change of the intensity index is closely related to the precipitation insouthwestern China.The precipitation in the southwestern part of the South Asianhigh-pressure strong year is generally high,the south Asian high-pressure is weak,the precipitation in the southwest is decreasing,and the South Asian high-pressureintensity is significantly positively correlated with the precipitation in the southwest.The strong current circulation situation in South Asia is more conducive toprecipitation,cyclone circulation is more likely to occur in high altitude,anticyclonic circulation is easy to occur in low altitude;vertical velocity rise ismore obvious in high altitude;low-level water vapor transport is closely related toprecipitation;high-level water vapor flux divergence to southwest precipitationMore instructive.(4)The intensity of South Asia high pressure is closely related to the temperature insouthwestern China.In South Asia,the temperature in southwestern China hasgenerally declined.In South Asia,the temperature in the southwest is weak,and thetemperature in the southwest is rising.When the South Asia high voltage isabnormal,the latent heat,sensible heat,and net short-wave radiation anomalies arenegative,and the net long-wave radiation is positive.The net long-wave radiantflux is proportional to the intensity of the South Asian high,and the latent heat,sensible heat,and net short-wave radiant flux are inversely proportional to theintensity of the South Asian high.Among the four heat fluxes,net short-waveradiation accounts for the main influence and is most closely related to temperaturechanges.When the South Asia high-voltage intensity is negative,the latent heat,sensible heat,and net short-wave radiation are positive,and the net long-waveradiation is negative.Among the four heat fluxes,net short-wave radiation accountsfor the main influence and is closely related to temperature changes.