日本における竜巻の統計的性質

Abstract

The statistics of Tatsumakis occurred in Japan are investigated for 32 years from 1961 to 1992. The total number of the occurrence of Tatsumakis for 32 years is 538 and the yearly average is 16.8. The largest probability of the occurrence in each prefecture in a year is Okinawa and the value is 7.49. The relative frequency of the cause of the occurrence of Tatsumakiis as follows; 24.3% for typhoons, 39.0% for fronts, 17.8% for lows and 18.8% for others. The 60% of Tatsumaki occur between July and October. The Tatsmakis associated with typhoons occur in the field near the coast line of the Pacific ocean.The yearly average of damages is as follows; 0.4 for the died, 23.5 for the injured, 27.6 for the completely destroyed houses, 329.8 for the partially damaged houses. The average of the damaged area is 119m for the width and 3.2km for the length.