Based on the 4 times daily 0.75°×0.75°ERA-Interim data,the relationship between precipitation and a transverse shear line(TSL)over Qinghai-Tibet Plateau during August 15-19,2015 is analyzed.The results ...Based on the 4 times daily 0.75°×0.75°ERA-Interim data,the relationship between precipitation and a transverse shear line(TSL)over Qinghai-Tibet Plateau during August 15-19,2015 is analyzed.The results show that precipitation and TSL had obvious diurnal variation.That is,the intensity of the TSL and the precipitation tended to increase from afternoon to night and reduce from 00:00 to 06:00 UTC(the same below).The shape of the rain area was basically consistent with the direction of the TSL,and when the zonal characteristics of the rain area were obvious,the precipitation distribution was relatively uniform,otherwise the local short-term heavy precipitation was easy to occur.The precipitation center was basically consistent with the positive vorticity center near the TSL,and precipitation was directly proportional to the value of positive vorticity.The equation for the budget of vorticity shows that the horizontal advection term determined the moving direction of the TSL.The vertical transportation term determined the structural characteristics of the TSL on the vertical section,and positive vertical transport item of lower level was conducive to the formation of the plateau vortex.The horizontal convergence or divergence term determined the position of the TSL,and was conducive to the maintenance of the TSL.The evolution of apparent heat source and apparent water vapor sink near the TSL had a distinct diurnal feature.Meanwhile,atmospheric heating in the precipitation process was closely related to atmospheric upward movement,and the latent heat of condensation release caused by precipitation was beneficial to the maintenance of the plateau shear line and the formation and strengthening of plateau vortex.The precipitation of the TSL was mainly dominated by weak convective precipitation.展开更多
基金Supported by Qinghai Science and Technology Department Project(2020-ZJ-739,2019-ZJ-A10)National Key Research and Development Program of China(2018YFC1505705)+1 种基金National Natural Science Foundation of China(91637105,41475041)Key Project of Qinghai Procincial Meteorological Bureau(QXZ2020-03)。
文摘Based on the 4 times daily 0.75°×0.75°ERA-Interim data,the relationship between precipitation and a transverse shear line(TSL)over Qinghai-Tibet Plateau during August 15-19,2015 is analyzed.The results show that precipitation and TSL had obvious diurnal variation.That is,the intensity of the TSL and the precipitation tended to increase from afternoon to night and reduce from 00:00 to 06:00 UTC(the same below).The shape of the rain area was basically consistent with the direction of the TSL,and when the zonal characteristics of the rain area were obvious,the precipitation distribution was relatively uniform,otherwise the local short-term heavy precipitation was easy to occur.The precipitation center was basically consistent with the positive vorticity center near the TSL,and precipitation was directly proportional to the value of positive vorticity.The equation for the budget of vorticity shows that the horizontal advection term determined the moving direction of the TSL.The vertical transportation term determined the structural characteristics of the TSL on the vertical section,and positive vertical transport item of lower level was conducive to the formation of the plateau vortex.The horizontal convergence or divergence term determined the position of the TSL,and was conducive to the maintenance of the TSL.The evolution of apparent heat source and apparent water vapor sink near the TSL had a distinct diurnal feature.Meanwhile,atmospheric heating in the precipitation process was closely related to atmospheric upward movement,and the latent heat of condensation release caused by precipitation was beneficial to the maintenance of the plateau shear line and the formation and strengthening of plateau vortex.The precipitation of the TSL was mainly dominated by weak convective precipitation.
