MIROC5 predictions of Yamase (cold northeasterly winds causing cool summers in northern Japan)

摘要

Cold northeasterly winds, called Yamase, which cause the summertime weather of northern Japan to be unusually cool, have often damaged the rice crop in northern Japan, both historically and recently. To estimate future Yamase event occurrences, we used the new version of the MIROC5 atmosphere-ocean general circulation model and predicted the frequency of future Yamase events from the pressure difference index (pressure difference between Wakkanai and Sendai; PDWS). In a 20th-century experiment (1980-2005), the PDWS simulated by the M1ROC5 model reproduced well the Yamase events in the JRA-25 reanalysis data. In a future climate experiment (2006-2100), the predicted occurrence frequency of Yamase events is low around the 2030s and from the 2080s onward, but in other periods, Yamase events are predicted to occur at about the same frequency as during the 20th-century experiment (1980-2005). Therefore, even under global warming, Yamase winds can be expected to affect agriculture in northern Japan in the 21st century.