Statistical Analysis of the Characteristics of Severe Typhoons Hitting the Japanese Main Islands

Abstract

Characteristics of 51 severe typhoons hitting the Japanese main islands with central pressure equal to or less than 980 hPa during the period 1955?94 were analyzed by an objective method using hourly station observation during typhoon passages. Position of a typhoon center, central pressure depth ?p, and radius of the maximum wind rm, were obtained at hourly intervals after landfall on the main islands of Japan. The pressure profile of severe typhoons used in this analysis was chosen from formulas presented in previous papers, namely the same as one used by the U.S. Army Corps of Engineers for hurricanes hitting Florida. Coastlines of the main islands were divided into three sections: areas A, B, and C extending from west to east. Statistical analyses of parameters were made for each area. At time of landfall, the maximum value of ?p was 83.2 hPa for area A, 85.2 hPa for area B, and 47.8 hPa for area C. The differences in return period of ?p among areas are considered to be caused by the SST distribution off the Pacific coast. On average, typhoons making landfall in area C have larger rm and speed, and display a more eastward component of translation than those in the other two areas. The differences of speed and direction among areas and months can be explained to be caused by variation of the synoptic-scale air current at the 500-hPa level.