Structures of convection and turbulent kinetic energy in boundary layer over the southeastern edge of the Tibetan Plateau

查看全文 作　　者：WANG [1,2]YinJun;XU [1]XiangDe;ZHAO [2]TianLiang;SUN [3]JiHua;YAO [1]WenQing;ZHOU [4,5]MingYu

机构地区：[1]Chinese Academy of Meteorological Sciences(CAMS);[2]Nanjing University of Information Science & Technology;[3]Meteorological Institute of Yunnan Province;[4]National Marine Environmental Forecasting Center;[5]National Climate Center,China Meteorological Administration

出　　处：《Science China Earth Sciences》索引2015年第58卷第7期,共12页

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41130960,41165001,41175010);the China Special Fund for Meteorological Research in the Public Interest(Grant No.GYHY201406001) 摘　　要：Based on a comprehensive analysis on Sonic Anemometer and gradient data, wind profile radar(WPR) and GPS sounding data of March–August 2008 from the boundary layer(BL) tower observation system at Dali on the southeastern edge of Tibetan Plateau(TP), it is found that the strengths of turbulent kinetic energy(TKE), buoyancy term and shear term depend on vegetation cover in association with local stability and thermodynamic condition. Strong kinetic turbulence appears when near surface layer in neutral condition with the large contribution from shear term. In an unstable condition within near surface layer, the atmospheric turbulent motion is mainly thermal turbulence, as buoyancy term is obviously larger than shear term. Under a stable condition the intermittent turbulence is accompanied by weak shear and buoyancy term, and TKE is significantly less than neutral or instable condition. The study also presents that the buoyancy term contribution at Nyingchi station in the southern slopes of the TP large topography in spring is significantly larger than that at Dali over the southeastern TP edge, reflecting that the thermal turbulence makes an important contribution to convection activity in the southern slopes of TP. Dali station is located in complex terrain with mountain and valley leading to larger kinetic turbulence. From the perspective of interaction of turbulence-convection in different scales, the study revealed that the height of convective boundary layer(CBL) could reach up to 1500–2000 m. TKE, shear term, and buoyancy term in near surface layer have the notable correlations with BL height and local vertical motion. The daytime thermodynamic turbulence effect of heat flux and buoyancy term has an obvious impact on the height of CBL, whereas mechanical turbulence only exerts a less impact. Mechanical turbulence in near surface layer has a significant impact on vertical motion especially in the forenoon with impacting height of 2500–3000 m. The peaks in diurnal variations of shear term and buoyancy term correspond to the high instable periods, especially in summer forenoon. Our observation analysis characterized the convection activity triggered by TKE source and their interaction in the southeastern TP edge. 关键词：对流边界层湍流动能对流活动青藏高原大气湍流运动不稳定状态结构南缘

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Structures of convection and turbulent kinetic energy in boundary layer over the southeastern edge of the Tibetan Plateau

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