Wave-CISK与快速增长的对称不稳定

Wave-CISK and the Fast Growth Symmetric Instability

本文应用一准两维的非静力平衡数值模式研究了凝结加热反馈对线性及非线性对称不稳定的影响。数值试验结果表明：当Ｒｉ＜１时，对于一定的加热廓线，Ｗａｖｅ－ＣＩＳＫ可以激发出快速增长的线性对称不稳定，其指数增长率比无加热时增加一倍半，并产生向暖区的移动，而加热廓线对对称不稳定的发生发展及结构都有明显的影响。具有凝结加热的非线性对称不稳定在其发展初期与线性情况相同，当扰动增长到一定强度，非线性作用增强，其不稳定增长速度就减慢，原来对称的环流结构被破坏，正环流不断减弱。

In this paper, a quasi-two-dimensional and nonhydrostatic model was used to study the effect of condensation heating on both the linear and the nonlinear symmetric instability. The results of numerical tests show that when the Richardson number Ri is smaller than 1, Wave-CISK can stimulate the fast growth SI. This symmetric instability propagates toward the warm area, and its growth rate is 1.5 times greater than that with no condensation heating. The development, evolution and structure of symmetric instability are also affected by the vertical distribution of heating. Nonlinear symmetric instability with condensation heating is very similar to the linear symmetric instability in the early period of the perturbations growing. With growth of the perturbations, the nonlinear interaction increases, and the symmetric structures are destroyed. The positive circulation is continuously weakened while the negative one is increased.