Relationship between Frost Damage of Tea in Uji city, Kyoto, Japan and the Recent Climate Warming

Abstract

A climatological survey was conducted on the occurrence of frost damage to the first tea crop, which has been increasing since the end of the 20th century in Uji area of Kyoto prefecture. The occurrence of frost damage was concentrated in the first half of April and was closely related to the average temperature in March, which is an important factor in the early start of the budding period. It has been proven that when the average temperature in March is high (low), the budding period in April starts early (late). In particular, the frequency of occurrence of frost damage is extremely high on days in April with low temperatures of 0 ℃ or below after the average temperature in March was 8 ℃ or higher. Since 1990, the warming of the climate has been accompanied by an increase in temperatures in most months of the year. Particularly, one interesting tendency has been found that when the temperature in March is high there is a non-increasing or even decreasing tendency of temperature in April. This tends to create favorable conditions for frost damage. The long-term change in the seasonal progression of temperatures from March to April is likely to be related to the singular changes in the seasonal progression of atmospheric circulation over and around the Japanese islands associated with the recent global warming in the region.