Monitoring of tropical cyclone structures in ten years of RADARSAT-2 SAR images

Abstract

The cross-polarized synthetic aperture radar (SAR) onboard the RADARSAT-2 satellite has the capability to simultaneously observe the tropical cyclone (TC) structure and ocean surface winds with high spatial resolution of ~1 km and large swath images of ~450 × 450 km. We propose a methodology to extract TC centers, radius of maximum winds, intensities and the azimuthal wave-number one asymmetric surface wind structures from 75 RADARSAT-2 cross-polarized SAR images over the period from 2008 to 2017. We present a quantitative investigation on both the symmetric mean flow and the asymmetries of azimuthal wave-number one in the surface wind fields retrieved from these SAR images. The results demonstrate that the radius of maximum wind decreases as maximum wind increases, which is consistent with the TC dynamic models for axisymmetric convective heating, and that TCs are more asymmetric when they are weak, and close to symmetric when they are strong.