Statistical analysis of surface wind distribution of typhoons on western North Pacific observed by scatterometer for 9 years

Surface wind distribution of typhoons over the western North Pacific is most important information for the safety of ships. For example, RSMC Tokyo-Typhoon Center in Japan Meteorological Agency issues the advisories of analysis and forecast of typhoons including maximum sustained wind speed and radii of over 50- and 30-knot wind areas. Such wind information is based on the hypothesis in which typhoons have almost axisymmetric surface wind distribution. On the other hand, from the observations by scatterometer on the low orbital satellite of QuikSCAT, it has been empirically understood that there are sometimes non-axisymmetric wind structures in typhoons.

In this study, typical surface wind distributions within typhoons over the ocean are revealed statistically for the first time by using the whole QuikSCAT observational datasets for typhoons from the start of its operation in 1999 to 2007. From the analyses, it is found that typhoons have non-axisymmetric surface wind distribtions basically. Besides, the geophysical and seasonal variations of the wind distributions are also investigated. The relation between the wind distribution and other physical parameters within typhoons such as vertical wind shear will be discussed.