Online ISSN : 1349-6476
ISSN-L : 1349-6476
Enhanced Subtropical Anticyclone over the Indo–Pacific Ocean Associated with Stagnation of the Meiyu–Baiu Rainband during Summer, 2020
Hiroaki UedaMikihiro YokoiMasaya Kuramochi
ジャーナル オープンアクセス

2021 年 17B 巻 Special_Edition 号 p. 14-18


During the early summer of 2020, a stagnation of the Meiyu-Baiu front brought torrential rainfall over East Asia. Meanwhile, the anticyclone was much enhanced over the subtropical western Pacific (SWP), which contributed abundant moisture to the Meiyu-Baiu rainband along the western rim of the anticyclone. Based on the sensitivity experiments of the linear baroclinic model by prescribing the observed diabatic heating anomalies, a combination of anomalous convection over the Indian Ocean and reduced rainfall over the western Pacific can account for the maintenance of zonally elongated SWP anticyclone. Interestingly, this period corresponded to the developing stage of La Niña, while the convective activities were notably suppressed over the warmed western Pacific. The sensitivity experiments to SST anomalies using the atmospheric general circulation model shows that the attenuated convection over the western Pacific can be ascribed to the warmed Indian Ocean associated with an atmospheric Kelvin wave wedge from the Indian Ocean. Overall, the suppressant SST effect of the Indian Ocean opposes and is greater than that of tropical Pacific. We issue a caveat regarding the additivity of the remote influence across the maritime continent. These results have important implications for the predictability of early summer rainfall over East Asia.

© The Author(s) 2021. This is an open access article published by the Meteorological Society of Japan under a Creative Commons Attribution 4.0 International (CC BY 4.0) license.

This article is licensed under a Creative Commons [Attribution 4.0 International] license.