Dr. Miyamoto presented a seminar on “A transition mechanism for rapid intensification of tropical cyclones”.
Most of strong tropical cyclones (TCs) experience a rapidly intensifying phase (Rapid Intensification: RI) during their lifetimes. Deep understanding of RI is essentially important for accurate prediction of TC intensity. Recently researchers pay increasing attention to RI and a number of studies have been conducted to reveal the structure and intensity change during the RI phase. The observational and numerical studies have shown that the cloud field has TC-like distribution, i.e., the presence of eye and eyewall, in the RI phase, suggesting that the flow structure is well axisymmetric.
This study mainly focuses on preprocesses of RI, which may possibly be important for RI prediction. We propose a transition mechanism from a slowly intensifying phase to the RI phase based on the idealized numerical simulations (shear-free cases) using a three dimensional full physics model. The mechanism emphasizes that a TC vortex needs to be well axisymmetric before RI starts and the RI initiates by the formation of eyewall that is defined as a region with large axisymmetric component of diabatic heating around the radius of maximum wind (RMW). This talk will introduce you the detail of proposed mechanism and the verifications based on the results of two papers published in Journal of the Atmospheric Sciences.
A recording of the presentation is available on the anonymous ftp site: