基本气流和边界层顶高度对低纬大气数值模拟的影响  

Influence of Basic Flow and Boundary Layer Top for a Low-Latitude Numerical Model

作　　者：王鹏飞[1,2] 黄平[1] 顾雷[3] 黄荣辉[1] 

机构地区：[1]中国科学院大气物理研究所季风系统研究中心,北京100190 [2]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029 [3]中国民用航空局空中交通管理局航空气象中心,北京100122

出　　处：《大气科学》2013年第5期1083-1090,共8页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展计划项目2011CB309704;国家自然科学基金资助项目41105047

摘　　要：本文研究了一个包含波动CISK(Convective Instability of the Second Kind)机制的扰动方程数值模式中,基本气流对低频振荡数值模拟的影响。结果显示,当基本气流为纬向均匀风场U时,振荡周期随U的增加而减小:当U取2 m s-1时,周期从50～60 d减小到30 d;当U减小到-1 m s-1时,振荡周期增加为70～80 d。这是由于低频振荡是从西向东传播,西风基本气流能加快扰动东传,反之东风基本气流会抑制扰动东传,使振荡周期增加。同时,模式中的边界层顶出现误差时,模拟结果会有敏感的响应。若边界层顶取值比标准值高,对流加热反馈作用过大,出现扰动增长过快的现象,传播到80°～90°E附近时,扰动不再继续传播,而是无限增长;而边界层顶取值比标准值低时,对流加热反馈过小,扰动增长小且衰减加快,扰动传播不远便耗散到零,扰动循环周期表现为热源的周期。The influence of the background flow and the boundary layer top parameterization error on the low-frequency oscillation of the tropical atmosphere is discussed using a simple three-dimensional numerical model including a wave-CISK mechanism. The results show that the velocity of horizontal background flow （U） has an important impact on the frequency of low-frequency oscillation. When the horizontal wind U=2 m/s, the oscillation period reduces from 50-60 days to 30 days, while when U=- 1 m/s the oscillation period increases to 70 days. Because the original oscillation moves eastward, a westerly flow can increase the oscillation while an easterly flow can restrain the oscillation and thus increasethe oscillation period. Moreover, the low-frequency oscillation appears to be sensitive to the parameterization error in the model. When the selected value of the boundary layer is larger （1070 m） than the standard value （1030 m）, the feedback of heat forcing is large. Thus, the oscillation moves faster than the standard speed and stops moving and increases toward infinity when the wave reaches 80°-90°E. On the contrary, when the selected value of boundary layer is smaller （1000 m） than the standard value, the feedback of heat forcing is not sufficiently large to maintain the oscillation. Thus, the wave will disappear within 110°-120°E, and the period is less than standard.

关 键 词：基本气流 边界层顶 误差 低纬模式 

分 类 号：P435[天文地球—大气科学及气象学]