Future Changes in Atmospheric Conditions for the Seasonal Evolution of the Baiu as Revealed from Projected AGCM Experiments

Journal of the Meteorological Society of Japan

Tetsuya TAKEMI¹  Hirohiko ISHIKAWA¹  Yasuko OKADA²  Ryo MIZUTA³  Shoji KUSUNOKI³ 

[1] Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan;Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan;Meteorological Research Institute, Tsukuba, Japan

关键词: precipitation;    the Baiu;    global warming;   

DOI  :  10.2151/jmsj.2017-013

学科分类：大气科学

来源: Meteorological Society of Japan

【 摘 要 】

 This study investigates future changes in atmospheric circulation during the Baiu in Japan using 20-km-mesh atmospheric general circulation model (AGCM) simulations for the present-day (1979-2003) and the future (2075-2099) climates under the Representative Concentration Pathways 8.5 scenario. The simulated future climates include the outputs obtained with one control sea surface temperature (SST) and three different SST patterns. The Baiu frontal zone, defined as the meridional gradient of equivalent potential temperature, gradually moves northward during June–July–August in the present-day climate. In the future climate simulations using the control SST, the Baiu frontal zone is projected to stay to the south of Japan in June. Thus, precipitation is projected to increase over this region, while decreasing in the western part of Japan. Future changes in precipitation and atmospheric circulations in June are consistent across all four SST patterns. However, precipitation and atmospheric circulation in July and August in the future climate simulation depends on the SST patterns as follows: in non-El Niño-like SST pattern, the Baiu terminates in late July, similar to that of the present-day climate; a result with an El Niño-like SST pattern shows that sufficient amount moisture is transported to the Japanese islands and leads in a delay of the Baiu termination until August; and in the SST pattern with strong warming in the western North Pacific (WNP), a sufficient amount of moisture is transported to the south of Japan from June until August. The difference in the SST pattern leads to a variation in sea-level pressure in the WNP and affects a variation of the Northern Pacific subtropical high around the Japanese islands in July and August.

【 授权许可】

Unknown