ISSN 1006-9895

CN 11-1768/O4

The Impact of Eastern Pacific Warm Pool and Meridional Wind Anomaly on the Genesis and Development of ENSO Event
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    Abstract:

    By means of LDEO sea surface temperature (SST) and NCEP/NCAR reanalysis wind from 1982 to 1999, the relations of the eastern Pacific warm pool (EPWP) and abnormal meridional wind to ENSO events are analyzed. The results show that the EPWP climatologic SST has a clear intraseasonal variability, which is very similar to El Niño event growth process, i.e., occurring in spring, developing in summer, maturing in autumn and decaying in winter, meanwhile, the meridional wind anomaly and its divergence both are closely related to ENSO events. Based on synchronous considerations, a concept model of the EPWP and the meridional wind anomaly (north wind anomaly and convergence of meridional wind anomaly divergence) affecting the genesis and development of ENSO events is suggested, specifically, the north wind anomaly transports EPWP warm water to the equatorial neighborhood by producing southward ocean current, which, in turn, is instrumental to Niño3 SST increase, almost in the meantime, EPWP equatorial abnormal meridional wind convergence not only causes the warm water from north bank to pile up near the equator but also suppresses the cold upwelling around the equator, which, in turn, are favorable to Niño3 SST increase. Such factors are (not) favourable to genesis and development of (La Niña) El Niño events. Further analysis indicates that EPWP and abnormal meridional wind only play a motivating (suppressing) not decisional role in the genesis and development of El Niño (La Niña) events. Considering EPWP and abnormal meridional wind with inclusion of the western Pacific warm pool and abnormal west wind perfects further genesis mechanism for El Niño events. Finally, the characteristics difference of El Niño events occurring between in the 1980s and in the 1990s is simply examined.

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  • Received:
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  • Online: April 26,2012
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