Structural Variation Of Upper Troposphere-lower Stratosphere And Troposphere-stratosphere Exchange Induced By A Strong Convective Weather Event

This paper we presented atmospheric compositions and thermal structure of the Upper Troposphere and Lower Stratosphere (UTLS) in a penetrating MCC occurred before and after 8 June 2009 between Guizhou and Guangxi provinces based on ERA-Interim data and simulation of Weather Research and Forecasting Model(WRF),combined with the satellite observations such as NASA "A-Train"formation, FY-2C, COSMIC and other satellite data . By adopting the high-resolution meteorological data-driven HYSPLIT 4.9 (Hybrid Single Particle Lagrangian Integrated Trajectory Model) output under WRF high precision meteorological field and through the analog calculation of forward and backward trajectories,this paper conducts discussion on the source zone, transport paths, the relative amount and time scale of the stratosphere troposphere exchange and transport (STE) during this process. The conclusions are as follows:(1) The MCC occurred in the south, north branch of the role of double slot.Guizhou and Guangxi border in the strong convergence zone, the formation of strong convective instability stratification, convergence rise inspired MCC. Also adequate water vapor and obvious vertical wind shear are conducive to the development of strong MCC.(2) The temperature profile and the ambient temperature profile within the MCC are greatly changed. The two CPT tropopause appear on the original 16.7km single CPT and there is an inversion in the middle. This abnormal temperature disturbance structure is in turn related to the convective adiabatic cooling zone in the upper part of the MCC, upward radiation cooling of cloud stocks, and the downward radiant heating of the anvil. It is also proved that the anomalous structure of the temperature is related to the gravity wave by the WRF simulation of the sponge layer scheme.(3) MCC through the strong upward movement, the lower ozone high ice water content (IWC) air transported to the high level, making the UTLS region ozone value is significantly lower than the MCC outside area, and IWC is higher than the MCC.In the high IWC zone at the top of the MCC, the water vapor concentration is mainly controlled by temperature from 17km, similar to the temperature distribution, making the water vapor distribution from bottom to top also appear low value of water vapor,high value and low value areas.(4) The reverse derivation of the backward trajectory indicate that STE in the MCC has two sources. Tracer particles located at the top of the MCC troposphere,part of the low-altitude atmosphere from the southwest Indian Ocean surface, guided by the southwest airflow in the south of the Bay of Bengal Bay, and transported to the low-level convergence zone in the northwest, within four hours, was quickly transported to the top of the troposphere, the process of delivery accounted for 36.6%of total tracer particles. While the other part comes from the northern part of the plateau, especially in the northern low-level tracer particles, transport is very slow.Push back 10 hours, tracer particles appear in the region. Until push back 12 hours,10.9% of the tracer particles appear in the area. This part of the particles by the north branch slot after the air guide, to the southeast direction. At the same time, the vertical position of the northward source area (northern plateau) is much higher than that of the southward source area(above the sea).(5) The forward trajectory analysis shows that STE has two transport paths.Tracer particles located at the MCC boundary layer, after 6 hours, 10.2% of the tracer particles were transported up by the MCC strong convection and quickly reached the top of the troposphere. Then the particles are affected by the peripheral circulation of the south side of South Asia High, the particles turn to the southeast. While the other part of the tracer particles by the slow frontal climb and rapid westerly jet interaction,will be slowly upward transport, and eastward extended to a very far position for the east branch transport path. 18 hours later, the tracer particles moving eastward along the frontal began to reach the upper level. After 36 hours, the large scale frontal transport reached the top of the troposphere and accounted for 7.3% of the total tracer.