Japan Geoscience Union Meeting 2014

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Poster

Symbol A (Atmospheric, Ocean, and Environmental Sciences) » A-CG Complex & General

[A-CG37_28PO1] Multi-scale ocean-atmosphere interaction in the tropics

Mon. Apr 28, 2014 6:15 PM - 7:30 PM Poster (3F)

Convener:*Nagura Motoki(Japan Agency for Marine-Earth Science and Technology), Takuya Hasegawa(Japan Agency for Marine-Earth Science and Technology), Ayako Seiki Ayako(Japan Agency for Marine-Earth Science and Technology), Tomoki Tozuka(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Hiroki Tokinaga(International Pacific Research Center, University of Hawaii), Masamichi Ohba(Central Research Institute of Electric Power Industry (CRIEPI), Environmental Science Research Laboratory), Yukiko Imada(Atmosphere and Ocean Research Institute, the University of Tokyo)

6:15 PM - 7:30 PM

★ [ACG37-P02] Seasonality of boreal winter MJO and its relation to SST variability

*Tamaki SUEMATSU1, Hiroaki MIURA1 (1.Graduate School of Science University of Tokyo)

Keywords: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.