- 公益社団法人 日本地理学会
- 地理学評論 (ISSN:00167444)
- vol.8, no.3, pp.203-213, 1932
Last year the harvest was poor in every district in Japan, especially in the Northeastern district of the Mainland and in Hokkaidô. The total rice yield in the Northeastern district and Hokkaidô is estimated as only onehalf that of normal years. There may be several causes of the poor harvest, such as typhoon, droughts, etcRI believe the poor harvest of the last year was due to low temperatures and reduced hours of sunshine. I have drawn 12 climatic maps based on data recorded in the Monthly Bulletin of the Central Meteorological Observatory, Tokyo.<br> From Figs. 7 and 8 we can easily understand that the climatic couditions that prevailed during June and July, 1931, were very unfavorable for the rice crop. The zones of -2.0 C and below it as the mean deviation of air temperature during June and July and those of -10% and below it as the mean deviation of sunshine percentage during June and July, are Aomori and Iwate Prefectures and Hokkaido. These zones correspond to the districts where the rice harvest was very poor.<br> I think that the reasons for low temperatures and lesser sunshine in Japan during June and July last year are as follows: As we can see in Fig. II, the center of the anticyclone in June was situated in the Okhotsk Sea, its barometric reading being above 761mm. Usually in June the anticyclone occupies the offing of the Sanriku district, resulting in the rainy season in Japan : but last year the center of the anticyclone migrated farther northwards and cold air was brought in by north-easterly winds.<br> During July last year the distribution of air pressure resembled that of ordinary years, but the weak high pressure zone still remained in the Okhotsk Sea, and that as many as twenty-five cyclones visited Japan, so that dull weather prevailed during nearly the whole of July. The original cause of the unfavorable climate was undoubtedly the abnormal high pressure that prevailed over the Okhotsk Sea during June last year.