Gaoyuan qixiang (Feb 2022)
Characteristics Analysis of the Land-atmospheric Water & Heat Exchanges over the Yarlung Zangbo Grand Canyon Region
Abstract
By using the ECMWF Re-Analyses version5 data， the water vapor transport type over the Yarlung Zangbo Grand Canyon area of southeastern Qinghai-Xizang Plateau（QXP）are categorized， the daily variation characteristics of land-atmospheric water heat exchange fluxes are analyzed at different locations under different water vapor conditions by choosing two observation stations in the Yarlung Zangbo Grand Canyon area， namely， the Pailong Station and the Motuo Station.The results show that： The plateau monsoon period is the period of strong water vapor transport and the warm-wet period in the Yarlung Zangbo Grand Canyon area， while the opposite is true for the Plateau non-Monsoon period.Daily variations of near-surface latent heat fluxes on typical sunny/cloudy days during the Plateau Monsoon/non-Monsoon period are more sensitive and consistent in response to atmospheric water vapor conditions at the Motuo and the Pailong stations.The daily variation of near-surface latent heat flux under strong water vapor conditions is stronger than that under weak water vapor conditions， and the most significant difference in daily variation of near-surface latent heat flux under different water vapor conditions is found at the low altitude and humid Motuo station， where the daily average of near-surface sensible heat flux under strong water vapor conditions （84.05 W·m-2） is about 1.13 times of that under weak water vapor conditions on a typical sunny day during the non-monsoon period on the plateau， and the daily variation can reach 345.37 W·m-2.Different characteristics of near-surface sensible heat fluxes at the two sites in response to different water vapor conditions during the highland monsoon and non-monsoon periods.The daily variation of near-surface sensible heat fluxes at the Pailong and the Motuo stations on typical clear days during the highland monsoon period is stronger under weak water vapor conditions than under strong water vapor conditions.The daily average and variation of near-surface sensible heat flux is most sensitive to the difference of water vapor conditions during the highland monsoon/non-monsoon period at the higher altitude Pailong station， and the daily average and diurnal range of sensible heat flux under weak water vapor conditions （32.71 and 191.1 W·m-2） is about 1.66 and 1.26 times higher than that under strong water vapor conditions under a typical sunny day during the highland monsoon period.The weakening effect of cloud cover and water vapor on solar short-wave radiation is greater than its own greenhouse effect.The daily variations of near-surface sensible heat fluxes at the Motuo and the Pailong stations under weak water vapor conditions on typical cloudy days during the highland monsoon/non-monsoon period are stronger than those under strong water vapor conditions， and the daily average values of near-surface sensible heat fluxes at the Pailong station under weak water vapor conditions on typical cloudy days during the Plateau Monsoon/non-Monsoon period are 35.12 and 14.32 W∙m-2 which are 2.59 and 1.27 times higher than those under strong water vapor conditions， respectively.The existence of water vapor transport channels in the Yarlung Zangbo Grand Canyon area， the radiation forcing of atmospheric water vapor has significant effects on the land-atmospheric water & heat exchanges process， the energy parting at the surface is controlled by the land surface property.
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