Large Scale Influences on Tropical Cyclogenesis

这项研究的目的是增加对热带气旋成因的了解。 特别令人感兴趣的是对尺度大于热带气旋的现象的成因的影响，因此更有可能被准确测量。 对于大规模现象的相对重要性以及它们影响这一进程的具体方式，社会上存在相当大的分歧。该项目包括三个相关的任务。 一个是继续观测研究，使用网格分析，前光标在东太平洋气旋，特别是背景状态的相对作用，山区的相互作用，上游大气波，和风涌。 PI还将调查季风槽在该地区的作用。 另外两个任务是处理东风波现象。 将完成位涡纬向梯度的符号反转及其对东风波和气旋生成的影响的全球气候学。 此外，还将进行东风波的数值模拟，从简单的浅水模式开始，然后转向更复杂的MM5模式。加强对热带气旋生成过程的了解是改进热带气旋预报的关键一步。

The objective of this research is to increase understanding of the genesis of tropical cyclones. Of particular interest are the influences on genesis of phenomena whose scales are larger than the tropical cyclone and, therefore, more likely to be measured accurately. There is considerable disagreement in the community regarding the relative importance of the large-scale phenomena and the specific ways in which they affect the process. This project consists of three related tasks. One is a continuation of observational studies, using gridded analyses, of the pre-cursors to cyclogenesis in the eastern Pacific, particularly the relative roles of the background state, mountain interactions, upstream atmospheric waves, and wind surges. The PI also will investigate the role of the monsoon trough in this region. The other two tasks deal with the phenomenon of easterly waves. A global climatology of sign reversals in the meridional gradient of potential vorticity and its influence on easterly waves and cyclogenesis will be completed. In addition, numerical simulations of easterly waves will be conducted, beginning with a simple shallow water model and moving to the more complex MM5 model. Improved understanding of the processes involved in tropical cyclogenesis is a key step in improving the forecasting of tropical cyclones.