[A-CG37_28AM2] 熱帯におけるマルチスケール大気海洋相互作用現象

★ [ACG37-P02_PG] 冬期MJOの季節性とSST変動との関係について

ポスター講演3分口頭発表枠

*末松 環¹、三浦 裕亮¹ (1.東京大学理学系研究科地球惑星科学専攻)

キーワード：MJO, SST variability, intraseasonal variability

Madden-Julian Oscillation (MJO) is a prominent intraseasonal variability in the tropics, which is characterized by eastward moving large-scale convective system along the equator. Overall seasonality of MJO paths has been recognized to be eastward during boreal winter and north-eastward during boreal summer. However, analysis of satellite data of NOAA Interpolated Outgoing Longwave Radiation (OLR) from 1982-2012 suggests that there is a notable variability in MJO paths just within boreal winter season. The paths of MJOs were observed to make a notable shift southward from about 10⁰N to 10⁰S from September to April, often with an event passing over the equator during November to December. Structural differences were also recognized between MJOs taking northern paths (northern MJO) and southern paths (southern MJO), with northern MJOs consisting of smaller convective components and being accompanied by more westward propagating components. Using weekly NOAA Optimum Interpolated Sea Surface Temperature (SST) data of the same time period, this shift in the paths of MJOs is further analyzed in relation to variability in SST distribution. Temporal changes in zonal SST gradient of MJO occurring regions, and equatorial asymmetry of SST distribution were evaluated. The result was suggestive of effective influence of positive zonal SST gradient from equatorial Indian Ocean to equatorial Western Pacific on the existence of MJO, and that equatorial asymmetry of SST distribution may be playing a part in the shift of the MJO paths.