The Characteristics Of Deep Convective Activity On The Qinghai-Tibet Plateau And Its Effect On The Transport Of Water Vapor In The Stratosphere

Tibetan Plateau as an important window for stratosphere-troposphere exchange,has a high frequency deep convection activity.The flourishing cumulus transport the water vapor and anthropogenic pollutants of planetary boundary layer into the upper troposphere and lower stratosphere,which further effect on the atmospheric composition and radiative balance over the tropopause layer.Advanced understanding for activity characteristic of deep convection and vertical transport of water vapor over the Tibetan Plateau and its southern slope is beneficial to recognize the latitudinal distribution difference of stratosphere water vapor,seasonal cycle of ozone valley over the Tibetan Plateau and increased aerosols layer on the tropopause layer.That's also advantageous to accurate estimate the contribution and function of deep convection of this region for increased water vapor of stratosphere,the recovery of arctic ozone hole and the global climate change.This paper uses multi-satellites observative datasets,including the GPM(Global Precipitation Measurement),COSMIC(the Constellation Observing System for Meteorology,Ionosphere,and Climate)and the A-train(the Afternoon Train)track' CloudSat,Aura and Aqua satellite,systematically analyze the deep convective activity characteristic,main detrainment layer,tropopause distribution and the change of ice water content and water vapor mixing ratio of two kinds of scenario.The principle conclusions are as follows:(1)The Tibetan Plateau has a prosperous cumulus activity,the frequency of convection precipitation is 65.43%,but weak and shallow convection has a large ratio,the frequency strong and deep convection over the Tibetan Plateau is lower than that over the southern slope.The frequency of deep convection over the Tibetan Plateau and its southern slope is 0.15% and 0.98% respectively.(2)Deep convection extensively distributed on the central and east of Tibetan Plateau and the arc region of the southern slope.Deep convection has an obvious intraseasonal variation owe to the South Asian monsoon and has a peak on July and August.A significant diurnal cycle of deep convection existed over the Tibetan Plateau and its southern slope,maximum numbers of deep convection is at the afternoon,but the difference of two sub-regions appears the night time.Tibetan Plateau rarely generated the nocturnal deep convection,and the southern slope is on the contrary.In addition,the vertical structure of deep convection including the mean cloud-top height and maximum echo intensity over the Tibetan Plateau is shallower and weaker than that over the southern slope.(3)Deep convection over the Tibetan Plateau and its southern slope has a higher main detrainment height than that over the tropical ocean,the main detrainment level distributed from 10 to 16 km.The max mass detrainment height over the Tibetan Plateau and its southern slope is 12.9 and 13.3 km.The nocturnal deep convection has a lower detrainment height but larger horizontal detrainment scale than the deep convection at afternoon.(4)the jointed CloudSat and Aura satellite observation show that the ice water content on deep convection scenario has a significant increase than on the non-deep convection scenario,the maximum increase appears at the 178hPa(~13km).The increment of ice water content over the Tibetan Plateau is higher than that over the southern slope.If wiping off the influence of deep convection,the ice water path over the whole Tibetan Plateau will decrease about 16.8%.(5)Deep convection over the Tibetan Plateau and its southern slope mainly contributed a hydrating function for the upper troposphere and lower stratosphere,but the hydrating degree is not consistent with the frequency and intensity of deep convection.Deep convection over the Tibetan Plateau mostly contributed an elevated water vapor ambient field,and deep convection over the southern slope has a less hydrating contribution and even dehydrating function over the part of tropopause layer.(6)The hydrating degree doesn't entirely depend on the detrainment height and intensity of deep convection,but instead upon the tropopause temperature,ambient relative humidity and cloud particle sizes and so on.Tibetan Plateau has a warm tropopause temperature,drier ambient humidity and smaller mean cloud particle sizes than the southern slope.Although high frequency and intensive deep convection mainly generated over the southern slope,the deep convection over the Tibetan Plateau has a stronger hydrating function for the upper troposphere and lower stratosphere than that over the southern slope.