風暴的二維數值模式之研究

A Study of Two-dimensional Model for Storm Simulation

陳景森(Ching-Sen Chen) ； 林熺閔(Shi-Ming Lin)

《大氣科學》 10卷1期 (1983/03) Pp. 55-66

摘要

本文建立一個二維的風暴數值模式，以研究風暴的結構與其發展過程，此二維數值模式是利用時間分割法來解可壓縮的運動方程組，有關聲波部份，即較小的時間間隔處理，利用半隱法求數值解，其餘部份利用二階跳蛙式計算。亂流量參數化的過程是根據Deardorff（1975）的亂流能量方程式求出渦流混合係數，此能量方程式包含浮力、風切與消散等效應。利用kessler（1969）的參數化方式處理雲的微物理過程。在側面邊界使用“開放式”的邊界條件來處理水平速度，目的是要讓模式內產生的重力波可以在最小的反射情形下，傳出側邊界外面。本文以1973年7月9日發生於美國科羅拉多州的一個風暴為例，探討風暴發展的過程。我們發現在風暴新生成的陣風鋒面前緣，有一個新生的雲胞發生，由於新生雲胞移動較暴風慢，兩者有機會合併，合併後，因風暴已開始進入消散的生命期，強烈的下降氣流把新生雲胞從原風暴的邊緣分裂出來。

並列摘要

A two-dimensional numerical model has been constructed in National Central University to investigate storms. This model solves the compressible equations of motion using a splitting scheme which treats the sound wave seperately. A scheme with second order in time and fourth order in space is used to solve advection term. For the subgrid turbulence processes, a time-dependent turbulence energy equation (Deardorff, 1975) is solved which depends on local buoyancy, shear and dissipation. Microphysical processes are included in the model using Kessler-type parameterization. An open boundary condition is incorperated in the model that respond to internal forcing and permit gravity waves to propagate out of the integration domain with minimal reflection. Using a Color ado storm which occurred on July 9 1973, we simulate the development of a new cloud cell forming in front of gustfront generated by old storm. The merging of the cloud cell and storm has been discussed.