The role of convective available potential energy for tropical cyclone intensification

所要求的研究项目将侧重于热带气旋发展的动态。将进行数值模式模拟并进行分析，以揭示CAPE在强化阶段是否存在，它是如何分布的，以及它可能对演化动力学起到的特殊作用。根据热带气旋发生的WISHE理论(WISHE=风致地表热交换)，在加强过程中不需要CAPE的存在。然而，这一理论只有在热带气旋外部区域的净潜热由于低相对湿度假设而消失的情况下才能得出决定性的结果。当CAPE可以储存在流入边界层中时，这种假设是不必要的。本文将采用轴对称云分辨模式HURMOD和三维云模式CM1进行研究。这项研究是基于这样一个假设，即CAPE有助于提高强化速率。这一假设可以通过一个简单的对流参数化方案得到验证，在该方案中，CAPE按规定的时间尺度减小。当强度也发生在任意小的松弛时间尺度上时，这表明WISHE是相关的。将开发一个概念模型，以使CAPE对强化的影响更容易理解。

The requested research project will focus on the dynamics of tropical cyclone development. Numerical model simulations will be conducted and analysed to reveal whether CAPE exists during the intensification phase, how it is distributed, and the particular role it may play for the evolution dynamics. According to the WISHE theory for tropical cyclogenesis (WISHE=Wind Induced Surface Heat Exchange), the existence of CAPE is not required in the intensification process. However, this theory only leads to a conclusive result, if the net latent heating in the outer region of a tropical cyclone vanishes due to the assumption of low relative humidity. Such an assumption is not necessary when CAPE can be stored in the inflow boundary layer. The axisymmetric cloud-resolving model HURMOD and the 3-dimensional cloud model CM1 will be applied for the study. The research is based on the hypothesis that CAPE contributes to an increase in the intensification rate. This hypothesis can be verified by a simple convective parameterization scheme, in which CAPE is reduced with a prescribed time scale. When intensification also takes place with an arbitrarily small relaxation time scale, this indicates that WISHE is relevant. A conceptual model will be developed to make the effect of CAPE on intensification more comprehensible.