洋面冷锋的三维数值模拟──潜热释放对冷锋结构的影响

A NUMERICAL INVESTIGATION OF THE IMPACT OF LATENT HEATING UPON THE STRUCTURE OF ACTIVE COLD FRONTS

中文关键词:  冷锋结构  数值模拟  潜热加热  三维中尺度模式

英文关键词:Structure of cold front  Numerical simulation  Latent heating  3D mesoscale model

中文摘要:

      通过比较一次洋面冷锋过程的干、湿三维模拟结果,揭示潜热释放对冷锋结构的影响。结果表明:由于潜热释放的作用,冷锋区的温度梯度和风矢量的气旋性切变大大地加强了,冷锋附近的涡度场和垂直速度场呈现出更多的更加紧密的中尺度结构;锋面非地转直接环流在湿模拟中比在干模拟中发展得更加充分并且具有更高的组织性;潜热加热倾向于增加锋面环流的强度,尤其是其上升支的强度。研究表明,潜热释放过程是形成冷锋前沿上方低层大气中狭窄强上升气流区的关键因素之一。

英文摘要:

      A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating upon the structure of active cold fronts.Results of the moist and dry simulations are compared to stress the effects of moist processes.It is found that both the temperature gradient and the cyclonic vorticity across the frontal zone are considerably increased due to the latent heating,especially in the lower troposphere.It is also noted that the cross-front ageostrophic direct circulation is more fully-developed and better organized in the moist case than in the dry case.The latent heating tends to enhance the intensity of the cross-front circulation.especially its ascending branch.Most importantly.our results indicate the important contribution by the latent heating to the formation of the intense narrow rising cell just above the leading edge of the cold front.