HR: 0830h
AN: GC31B-0170    [PDF]
TI: Interannual Variability Observed in the Early Summer Climate in the Western North Pacific
AU: * Tomita, T
EM: tomita@sci.kumamoto-u.ac.jp
AF: Dept. of Environmental Sci./Kumamoto Univ., Kurokami 2-39-1, Kumamoto, 860-8555 Japan
AU: * Tomita, T
EM: tomita@sci.kumamoto-u.ac.jp
AF: FRSGC/IGCR, Kanazawa-ku, Showa-machi 3173-25, Yokohama, 236-0001 Japan
AU: Yoshikane, T
EM: yoshikat@jamstec.go.jp
AF: FRSGC/IGCR, Kanazawa-ku, Showa-machi 3173-25, Yokohama, 236-0001 Japan
AU: Yasunari, T
EM: yasunari@ihas.nagoya-u.ac.jp
AF: FRSGC/IGCR, Kanazawa-ku, Showa-machi 3173-25, Yokohama, 236-0001 Japan
AU: Yasunari, T
EM: yasunari@ihas.nagoya-u.ac.jp
AF: HyARC/Nagoya Univ., Chikusa-ku, Furo-cho, Nagoya, 464-8601 Japan
AB: The early summer climate in the western Norh Pacific is largely controlled by the Baiu phenomenon. The interannual meridional fluctuation of the Baiu front and the relevant large-scale circulations are examined using empirical orthogonal function (EOF) analysis and the composite or correlation analyses based on the EOF time coefficients. The first EOF mode indicates the low-frequency fluctuation with a period of four to five years (LF mode) appearing to the south of 35$\deg$N. The development is concurrent with the horseshoe sea surface temperature anomalies (SSTAs) in the entire tropical Pacific that are associated with the El Ni¤o/Southern Oscillation (ENSO). The westernmost SSTAs control the anomalous southward expansion of Baiu front through the modification of convection around 20$\deg$-30$\deg$N in the western Pacific. The LF mode is negatively correlated with the activity of South-Southeast Asian summer monsoon. The second EOF mode is characterized by the meridional seesaw-like fluctuation with a node around 28$\deg$N and by the time scale of biennial oscillation (BO mode). The horseshoe SSTAs again control the mode but with the different spatial phase in the tropical western Pacific through the anomalous convection off the Philippines. The BO mode has the negative correlation with the activity of tropical western North Pacific monsoon. The SSTAs associated with the BO mode tend to be confined to the tropical western Pacific, while the signals of LF mode rather extend in the tropical Pacific-Indian Ocean sector broadly, suggesting that the tropical BO is the aborted ENSO being dominant in the tropical central-western Pacific. The spatial phase of horseshoe SSTAs adjusts the detailed interannual variability in the meridional fluctuation of Baiu front.
DE: 1655 Water cycles (1836)
DE: 1699 General or miscellaneous
DE: 3309 Climatology (1620)
DE: 3319 General circulation
DE: 3354 Precipitation (1854)
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting