Intensification of Typhoon Danas (1324) Captured by MTSAT upper tropospheric atmospheric motion vectors

Abstract

This study exemplifies a capability of upper tropospheric Atmospheric Motion Vectors (AMVs) derived from successive imagery of MTSAT-2 images to detect the intensification of Typhoon Danas (1324). The evolution of the wind field around the cloud top captured by the AMVs revealed two remarkable features: increases of radial outflow, representing secondary circulation in the form of the two convective bursts (CBs), and increases of tangential winds after the first CBs and during the second CBs. It is suggested that the updrafts and latent heat release associated with the first CBs induced increases of lower tropospheric convergence and absolute angular momentum. This preconditioned the axisymmetrization and increase in tangential velocity and inertial stability during the second CBs that led to tropical cyclone (TC) intensification. These results show that upper tropospheric AMVs can be used to detect TC intensification and thereby improve TC forecasts.