The role of convective available potential energy for tropical cyclone intensification

• Applicant: Privatdozent Dr. Thomas Frisius
• Subject Area: Atmospheric Science
• Term: from 2013 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 239585894

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.

• DFG Programme: Research Grants