[A-CG30] Multi-scale ocean-atmosphere interaction in the tropics

[ACG30-05] The intraseasonal relationship between the boreal summer intraseasonal oscillation and the Pacific-Japan pattern

*Ayako Seiki¹, Yu Kosaka², Satoru Yokoi¹ (1.Japan Agency for Marine-Earth Science and Technology, 2.The University of Tokyo)

Keywords:the boreal summer intraseasonal oscillation, the Pacific-Japan pattern

The influence of the dominant tropical intraseasonal variability during boreal summer, called the boreal summer intraseasonal oscillation (BSISO), on the tropical-midlatitudes teleconnection, called the Pacific-Japan (PJ) pattern, is investigated. A lag correlation analysis between the intraseasonal PJ index and phases of the BSISO index shows that the positive correlation between the BSISO and the PJ pattern peaks during the early stage of the BSISO phase 8 when the center of the BSISO enters the central north Pacific. Composite analysis based on the BSISO events shows that intraseasonal responses to the migration of the BSISO are apparent even in midlatitudes. During the phase 7-8, cyclonic wind anomalies with low pressure signals north of the Philippines are drastically intensified and easterly wind anomalies blow into the southern side of Japan. Apparent intraseasonal signals in surface pressure anomalies are also found over the central north Pacific around 40°N. The migration of the BSISO might influence summer climate in East Asia through the PJ pattern at intraseasonal time scales.