OSD Ocean Science Discussions OSD Ocean Sci. Discuss. 1812-0822 Göttingen, Germany 10.5194/osd-5-163-2008 Joint effect of the western and eastern Pacific warm pools on ENSO cycle Qi Q. 1 2 Hou Y. 1 Zhang Q. 1 Yan T. 3 Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China The Graduate School of the Chinese Academy of Sciences, Beijing 100039, China Climate Prediction Center, NOAA, Suitland MD 20746, USA 28 05 2008 5 2 163 185 Copyright: © 2008 Q. Qi et al. 2008 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://os.copernicus.org/preprints/5/163/2008/osd-5-163-2008.html The full text article is available as a PDF file from https://os.copernicus.org/preprints/5/163/2008/osd-5-163-2008.pdf

The zonal displacement of the western Pacific warm pool (WPWP) and the meridional displacement of the eastern Pacific warm pool (EPWP) and their responses to wind anomalies over the tropical Pacific were investigated. Joint effect of the WPWP and EPWP on ENSO was examined based on a joint effect index, which is a combination of the standardized anomaly time series of the eastern edge of the WPWP and the southern edge of the EPWP. Results show that both WPWP and EPWP are major providers of warm water in the eastern equatorial Pacific. The anomalous eastward extension of the WPWP and abnormal southward extension of the EPWP can supply a large amount of warm water into Nino3 region of the north equator, result in dramatic local SST increase, and trigger El Niño. To the contrary, as scope of the WPWP retreats westward and the EPWP retreats northward, a La Niña will outburst. One cannot separate apart the roles played by the WPWP and EPWP on ENSO, and the joint effect of both warm pools must be considered. A joint index of 1.6 means a new El Niño event is likely to happen.

 References Battisti, D. S.: The dynamics and thermodynamics of a warm event in a coupled ocean-atmosphere model, J. Atmos. Sci., 45, 2889–2919, 1988. Bjeknes, J.: Atmospheric teleconnections from the equatorial Pacific, Mon. Weather Rev., 97, 163–172, 1969. Can, M. A. and Zebiak, S. E.: A theory for El Niño and Southern Oscillation, Science, 228, 1085–1087, 1985. Ding, Y. and Jang Z.: Processing for the signal of meteorological data series, Beijing, Meteorology Press, 46–47, 1998 (in Chinese). Fu, C., Diaz, H. F., and Fletcher, J. O.: Characteristic of the response of sea surface temperature in the central Pacific associated with warm episodes of the Southern Oscillation, Mon. Weather Rev., 114, 1716–1738, 1986. Hirst, A. C.: Unstable and damped equatorial modes in simple coupled ocean-atmosphere model, J. Atmos. Sci., 43, 606–630, 1986. Huang, R. and Fu, Y.: Some study advancements and issues on the dynamics of ENSO cycle. The process and diagnose of the disaster climate, Beijing, Meteorology Press, 172–188, 1996 (in Chinese). Long, B., Li, B., and Zou, E.: Anomalous eastward displacement of the western tropical Pacific warm pool and warming of the eastern tropical Pacific, Acta Oceanol. Sin., 20(2), 35–42, 1990. Namias, J.: Some statistical and synoptic associated with El Niño, J. Phys. Oceanogr, 2, 130–138, 1976. Neelin, J. D.: The slow sea surface temperature mode and the fast-wave limit: analytic theory for tropical interannual oscillations and experiments in a hybrid coupled model, J. Atmos. Sci., 48, 584–606, 1991. Philander, S. G., Yamagata, T., and Pacanowski, R. C.: Unstable air-sea interactions in the tropics, J. Atmos. Sci., 41, 604–613, 1984. Shi, N.: The multivariate analysis method in research and prediction on meteorology, Beijing, Meteorology Press, 34–40, 2002. Suarez, M. J. and Schopf, P.: A delayed action oscillator for ENSO, J. Atmos. Sci., 45, 3283–3287, 1988. White, B. B, Meyes, G. A., and Songuy, J. R.: Short-term climatic variability in the thermal structure of the Pacific Ocean during 1979–1982, J. Phys. Oceanogr, 15, 917–935, 1985. Wyrtiki, K.: El Niño?the dynamic response of equatorial Pacific Ocean to atmospheric forcing, J. Phys. Oceanogr., 5, 572–583, 1975. Zhang, Q., Hou, Y., and Cheng, M.: Eastern Pacific warm pool, Adv. Water Sci., 17(5), 676–684, 2006. Zhang, Q. and Weng, X.: Analysis of some oceanographic characteristics of the tropical western Pacific warm pool, Studia Marina Sinica, 31–38, 1997. Zhang, Q, Weng, X., and Hou, Y.: Zonal movement of surface warm water in the western Pacific warm pool, Acta Oceanol. Sin., 26(1) 33–39, 2004.