Typhoon Eye Observations Using SAR and MTSAT

Abstract

Typhoon eyes have been delineated from the smoother area in the Radarsat Synthetic Aperture Radar (SAR) images of ocean surface roughness and from the warmer area in the Multi-functional Transport Satellite (MTSAT) infrared images by using wavelet analysis. Case studies for different typhoons and environment have been investigated to demonstrate that SAR can be a powerful tool to help in typhoon tracking and prediction, especially at the ocean surface. It is found that the distance between the center locations of these typhoon’s eyes, as determined by SAR and MTSAT, respectively, is quite significant (14–26 km) for all five cases. The result of large center distance between typhoon eyes at the cloud level from MTSAT data and on the ocean surface from SAR data implies that the eyewall shaft may be highly tilted and the vertical wind shear profile is more complex than generally expected. Some of the issues concerning the definition of typhoon eye and typhoon tracking/prediction have been identified and compared with other data sets. Also, the tilted structure and associated vertical wind shear, especially during typhoon turning and staggering, may be caused by the ocean feedback or island blocking effects.