Evaluation of factors of salty wind damage to rice plant in Shonai area of Yamagata prefecture from the view point of Typhoon characteristics after 1971 which passed on the Japanese Sea.

Abstract

We evaluated the factors of salty wind damage of rice plants in the Shonai area of Yamagata prefecture after 1971. The number of typhoons that occurred in the North Pacific Ocean decreased significantly, and those that passed over the Japan Sea indicated no trend. Seawater temperature in midsummer in the southern part of the East China Sea became significantly higher. Typhoon numbers that blew over 15 m s^-1 increased, and those under 1,000 hPa increased in decadal units. This showed a significant linear correlation between atmospheric pressure and maximum wind velocity, maximum wind velocity and hours over 10 m s^-1, respectively. Wind directions were from north-northwest to southwest when wind speed was at its maximum in the Shonai area, excluding Typhoon No.16 in 1974 and No.8 in 1978. Precipitations during the 24 hours after a typhoon had passed were 15 mm or less, excluding Typhoon No.8 in 1974. Typhoon numbers that passed in the 30 days after the heading showed no tendency in decadal units.