THEORETICAL RESEARCH ON THE COLD SURGE OF THE QINGHAI-XIZANG PLATEAU AS A HUGE OROGRAPHY

In terms of the linear shallow-water-wave equations involving in themselves:huge-topographic effect, two kinds of gravitational wave solutions are derived with the assumption that the plateau in question is a vast topography, inclined at a constant slope from west to east. One kind of the solutions is two high-frequency solutions of the inertia-gravitational wave pattern, another kind of that is one low-frequency solution of the orographic gravitational wave pattern excited by the huge-topography, the latter is similar to Kelvin wave in some ways. They are similar to the gravitational wave that the front of cold surge advances southward fast and to that the center of strong windspeed of cold surge moves towards the south along the eastern brim of the vast orography slow, respectively, the results are obtained by the numerical experiments. Especially, if it is no topography, the low-frequency wave vanishes but the high-frequency waves are available. It is also pointed out that the path of gravitational wave rays is a hypocycloid equation. The result agrees quite well with the path that indicates the center of the cold surge strong wind moves in a curved path along the eastern fringe of the Qinghai-Xizang Plateau. There might be the waveguide of orography-gravitational wave along the coastal areas in the east of the huge-topography.