| The plateau vortex generated over main part of the Tibetan Plateau in summer is one type of subsynoptic scale low-pressure vortex and a primary kind of synoptic systems in the Tibetan Plateau. It is mainly on the 500hPa isobaric surface, its mean horizontal scale is from 400 to 500 km, its vertical thickness is usually under 400hPa isobaric surface, its life circle is from one to three days, and temperature structure of most plateau vortex is warm. The plateau vortices are usually generated in the middle-west of the Tibetan Plateau, and develop in the process of moving eastward along the shear line of about 32oN. Finally, most vortices weaken or disappear in the downhill terrain of eastern plateau and only minority vortices can move out of the plateau. The vortex over the Tibetan Plateau is the main rainfall system of the Tibetan Plateau in summer and is advantageous to a severe weather process. It is noticeable that individual vortex can develop and move eastward out of the Tibetan Plateau coupled with the advantageous circulation patterns, which always gives rise to large-scale rain storm or thunderstorm in the east side of the Tibetan Plateau (especially in Sichuan basin), even in the east of China. Therefore, the study on plateau vortex is not only an important problem of theoretical research in meteorology of the Tibetan Plateau, but also has practical meanings of improving the weather forecast accuracy of the Tibetan Plateau and its adjacent areas.In the chapter 1, the scientific background and significance of this study is summarized firstly. Then the research progresses of plateau vortex in the field of the Tibetan Plateau meteorology since late 70's in 20th century is entirely reviewed. The research is classified into three aspects: synoptic meteorology, dynamics and numerical simulation, and the major achievements and the existent problems of the research are summarized. Finally, the objectives and contents of this study are put forward.In the chapter 2, the surface heat source over the Tibetan Plateau and its influence is analyzed. The results show that: the surface heat source over the plateau region in winter is negatively correlated with the summer rainfall over the mid-lower reaches of the Yangtze River, and positively correlated with rainfall in North China and the coast of Southeastern China. And the summer rainfall in the mid-lower reaches of the Yangtze River also has negative correlation with the surface heat source over the southern plateau, positive correlation with the surface heat source over the northern plateau in spring, with the distinctive correlation areas in the Karakorum Mountain and the Nyainqentanglha Mountains. The surface heat source over the Tibetan Plateau in both winter and spring are important influence factors on the summer rainfall in China. The plateau heating has import influence on the weather and climate of the Tibetan Plateau and its surroundings.In the chapter 3, the character of solitary wave and the evolution mechanism of the plateau vortex are studied in the nonlinear dynamics. The KdV equation is derived from nonlinear inertial gravitational wave equation using method of phase plane analysis and two types of solitary wave solutions with weather meanings are obtained by a direct integration method. We specially analyze the characteristics of singular solitary wave which has the association with the vortex over the Tibetan Plateau, and then discuss the effects of the plateau diabatic heating and the atmospheric stability on the origin, the movement, the vertical motion, the horizontal divergence, and the structure of warm core of the plateau vortex. There are some results of the plateau vortex in the viewpoint of nonlinear dynamics as follows:(1) When the atmosphere stratification is unstable, the plateau vortex will move eastward. And the diabatic heating is advantageous to the moving eastward of the plateau vortex.(2) The plateau vortex that moves eastward in the unstable atmosphere is the system with larger horizontal scale and smaller vertical scale.(3) When the horizontal speed of the plateau vortex is faster, the amplitude of its vertical motion is larger.(4) The plateau vortex has the features of vortex eye and warm core similar to the tropical cyclone-like vortices (TCLV) under certain conditions.In the chapter 4, the characteristics of TCLV and the evolution mechanism of the plateau vortex are studied in the viewpoint of vortex dynamics. Using the Boussinesq approximation, the vortex in the boundary layer is assumed to be axisymmetrical and thermal-wind balanced system forced by diabatic heating and friction, and is solved as an initial-value problem of linearized vortex equation set in cylindrical coordinates. The impacts of thermal forcing on the flow field structure of vortex are analyzed. It is found that thermal forcing has significant impacts on the flow field structure, and these impacts are closely related to the radial distribution of heating. There are some preliminary results about the thermal forcing on the structure of plateau vortex like TCLV as follows:(1) With joint effects of heating and friction of atmospheric boundary layer, the temperature field structure of plateau vortex shows warm core.(2) There is a dynamic neutral height in the divergence field of the plateau vortices like TCLV forced by heat source, and this height is related to the thickness of atmospheric boundary layer.(3) For the Ekman pumping effect, if there is cyclonic vorticity on the top of the boundary layer, it will induce convergence and increasing azimuthal motion; and if there is cyclonic airflow on the top of the boundary layer, it will force ascent motion.(4) If the heating distribution shows the type of"inner-cold and outer-hot"in the center of vortex, the heating will force divergence and weakening azimuthal motion in the lower layer of atmosphere, convergence and the strengthening azimuthal motion at the upper layer. Thus, the descent motion is beneficial to forming the field structure with vortex-eye and plateau vortices like TCLV.
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