日本地球惑星科学連合2018年大会

講演情報

[EE] Eveningポスター発表

セッション記号 A (大気水圏科学) » A-OS 海洋科学・海洋環境

[A-OS08] 季節から十年規模の気候変動と予測可能性

2018年5月20日(日) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:望月 崇(国立研究開発法人海洋研究開発機構)、V Ramaswamy(NOAA GFDL)、森岡 優志(海洋研究開発機構)

[AOS08-P10] 5月の梅雨前線の経年変動特性

*冨田 智彦1山浦 剛2 (1.熊本大学大学院 先端科学研究部、2.理化学研究所 計算科学研究機構)

キーワード:梅雨前線、経年変動、予測可能性

The Baiu front (BF) is a subsystem of the Asian summer monsoon bringing the rainy season in the East Asia – western North Pacific sector in June and July, which is usually formed in May. This work examines the interannual variability of the BF in May, diagnosing the global objective reanalysis data for the period of 1979-2015 (37 years).

In May, the two regions with relatively large precipitation expanding in southeastern China and to the southeast of Japan are connected by the activation of rainfall between them and form a large-scale zonal front, i.e., the BF. The activation is induced by the temperature advection in the middle troposphere from the south. Thus, the interannual variability of BF in May is caused by the timing and the strength of this temperature advection from the south. The anomalous cyclonic circulation appearing in the region of 5° - 35°N, 100° - 140°E controls the timing and the strength. This work further found that this anomalous cyclonic circulation was remotely forced as the Rossby type response of the intraseasonal oscillation (ISO) propagating on the equator from the Indian Ocean to the Pacific. Thus, the anomalous features of ISO near 130°E on the equator modulate the interannual variability of BF in May. The eastward propagation of ISO from the Indian Ocean to the Pacific on the equator implies that there exists predictability for the activity of BF in May.