On the intensification of typhoon Damrey with the monsoon gyre

Abstract

AbstractTyphoon Damrey, the first named tropical cyclone (TC) of the year 2000 in the western North Pacific, was embedded in a monsoon gyre (MG) during its intensification period. We explored the mechanisms of its rapid development and the contribution of the MG using a localized, instantaneous energetics diagnostic tool: the multiscale window transform (MWT) and MWT‐based multiscale energetics analysis. We used the ERA5 reanalysis dataset to obtain the fields on three temporal scales: TC‐scale fields; MG‐scale fields; and large‐scale background fields. The canonical transfer of kinetic energy from the large‐scale background fields to the tropical cyclone was negligible, whereas the MG increased the TC‐scale kinetic energy in the precipitation active quadrant and weakened its kinetic energy in the precipitation inactive quadrant. Barotropic canonical transfer therefore did not contribute to the development of this tropical cyclone. Kinetic energy was produced in Damrey mainly through buoyancy conversion and pressure work. In the upper troposphere, the available potential energy converted to TC‐scale kinetic energy, but this was mostly offset by the negative work done by the pressure gradient force with the updraught near the eyewall. In the lower troposphere, TC‐scale kinetic energy was produced by horizontal pressure work due to the inflow. This new finding helps us to understand the impact of the MG on the TC intensification and the underlying mechanisms governing TC evolution.