Relationships between Tropical Cyclone Motion and Surrounding Flow with Reference to the Maximum Sustained Wind and Longest Radius

This study statistically examines relationships between the motion and ambient flow of tropical cyclones over the western north pacific basin with reference to the maximum sustained wind (MSW) and longest radius (LR). Typhoon motion, MSW, and LR are based on the best track dataset compiled by the Japan Meteorological Agency (JMA). The steering flow is defined as the reanalyzed wind (provided by JCDAS) averaged between 1000 hPa to 300 hPa over areas within a 300, 400, and 500 km radius from the center of a typhoon. Results of this analysis reveal that the percentage of typhoons moving towards the north-east direction relative to the steering flow increases as the MSW intensifies and LR becomes larger. Same results are obtained, even if small scale motions around the typhoon are smoothed out and larger-scale motions are focused on. When the typhoons in the lower ( < 20°N), mid-latitudes ( 20-30 °N ) and higher ( > 30 °N) latitudes are considered separately, it is turned out that these results reflect the features of the mid-latitudes typhoon.