大气中尺度涡旋的三维螺旋结构理论

THEORY OF THE 3-D SPIRAL STRUCTURE FOR MESO-SCALE VORTEX IN THE ATMOSPHERE

文中应用描写大气运动的方程组求得了中尺度涡旋的三维定常流场以及相应的压力场和温度场 ,其中的三维流场构成了物理空间的一个非线性自治动力系统。理论分析和计算表明 :若中尺度涡旋的下层流体呈气旋 (反气旋 ) ,且伴有水平辐合 (散 )的螺旋转动 ,则通过上升(下沉 )运动 ,其上层流体呈反气旋 (气旋 )且伴有水平辐散 (合 )的螺旋转动 ,从而形成中尺度涡旋的三维螺旋结构。这些都与实际大气中的中尺度涡旋结构相似。它充分说明 :在旋转有粘性的大气中 ,为了保证质量守恒 ,必须有这种螺旋结构。

In this paper, the steady 3 D stream field and the corresponding Pressure and temperature(density) field are obtained from the equations describing the meso scale vortex in the geophysical fluid. The 3 D velocity fields construct a nonlinear autonomous system in the physical space. It is shown that the centres of the cyclonic(anticyclonic) are low pressure(high pressure) with the horizontal convergence(divergence) motion in lower levels and the results are just the contrary in upper levels. So there exists the 3 D spiral structure in the meso scale vortex, there are in conform fairly well with observations. It implies that the rotation of earth and viscosity of fluid play an important role in the spiral structure in order to ensure the mass conservation.