[A-CG39] 熱帯インド洋・太平洋におけるマルチスケール大気海洋相互作用

[ACG39-06] Relationship between rainfall at Cherrapunji, northeast India and anomalous anticyclonic circulation over western North Pacific

*村田 文絵¹、寺尾 徹²、藤波 初木³、林 泰一⁴、浅田 晴久⁵、松本 淳⁶、Syiemlieh Hiambok, J. ⁷ (1.高知大学理工学部、2.香川大学教育学部、3.名古屋大学宇宙地球環境研究所、4.京都大学東南アジア地域研究研究所、5.奈良女子大学文学部、6.首都大学東京、7.North Eastern Hill University)

キーワード：インドモンスーン、季節内変動、地形性降水

The characteristics of active rainfall spells (ARSs) at Cherrapunji, northeast India, where extreme high rainfall is experienced, and their relationships with large-scale dynamics were studied using daily rainfall data association with ARSs. The extremely large amounts of rainfall in the monsoon season are determined by the cumulative rainfall during ARSs. ARSs start when anomalous anticyclonic circulation (AAC) at 850-hPa propagates farther westward and suppresses convection over central India during ARSs at Cherrapunji, and continues for 3 to 14 days. Consequently, a northward shift of the monsoon trough during the 'break' in the Indian core region occcurs. The westerly wind, which prevails in the northern portion of the AAC, transports moisture toward northeast India and enhances moisture convergence over northeast India with southerly moisture transport from the Bay of Bengal, and greatly intensifies the orographic rainfall. In the upper troposphere, the Tibetan high tends to extend southward with the onset of ARSs. A linear relationship can be seen between the length and total rainfall of an ARS. Longer ARSs tend to result in greater total rainfall. AACs with a greater zonal-scale tend to produce longer and more intense ARSs. This study provides evidence for the effect of western North Pacific AACs on the Indian summer monsoon.