A group of Professor Hiroaki Ueda and Assistant Professor Youichi Kamae of the University of Tsukuba has analytically and experimentally revealed that the frequency of typhoons fluctuates due to the El Nino phenomenon in the tropical Pacific Ocean and the subsequent changes in sea surface temperature in the Indian Ocean. I made it.
The disappearance of potato chips from stores in 2017 was due to the drop in potato production in Hokkaido due to the record heavy rains caused by the frequent typhoons in 2016.On the other hand, the El Nino phenomenon (seawater temperature fluctuation) reaches its maximum in winter and then gradually decays, so it was said that the effect on the occurrence of typhoons from spring to summer would be weak.However, it shows a significant relationship between the two statistically, and it was necessary to investigate in detail.
Recent studies have shown that seawater temperatures in the Indian Ocean rise from spring to early summer, about half a year after the El Nino phenomenon, and the associated hyperbaric circulation (downdraft) is enhanced over the distant tropical western Pacific Ocean. I've come to understand that.Therefore, the research group extracted the El Nino phenomenon that occurred in the past, and investigated various observations during the decline period and the frequency of typhoons in the climate model experimental data set.
As a result, the number of typhoons will decrease over the tropical Pacific from spring to autumn after the peak of La Niña due to the combined effects of La Niña in the tropical Pacific Ocean and the seawater temperature of the Indian Sea that fluctuates in conjunction with it. It was revealed that the number will increase mainly in the South China Sea from the latter half of summer to autumn.
Due to the development of climate and ocean dynamics, the occurrence of the Ernino phenomenon can be predicted with a high probability from half a year ago, which greatly contributes to risk management in various socio-economic activities, including measures against typhoon damage in Japan. It is expected.
