Abstract
The effects of intra-seasonal wind forcing on the mean field of the tropical Pacific Ocean has been studied using an ocean general circulation model (GCM). Idealized intra-seasonal zonal wind forcing with zero mean, which propagates eastward, induces net eastward jets at the equator that shift the warm water pool to the east. The mean temperature of the upper 200 m of the ocean increases off the equator and decreases at the equator. The change is independent of the propagation speed of the intra-seasonal wind forcing. The magnitude of the change depends on the amplitude and the period of the forcing, and the ocean structure, while the spatial pattern is independent of these parameters. A simple shallow water model is used to explain these changes. It is found that the term responsible for the enhanced eastward Equatorial jet is the Reynolds stress term, which arises from a phase shift of the zonal current due to friction. The resultant convergence of eastward momentum on the equator and geostrophic adjustment of the interface to the change of zonal current brings about the thermal redistribution of the upper ocean seen in the GCM.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Battisti, D. S. (1988): Dynamics and thermodynamics of a warming event in a coupled atmosphere-ocean model. J. Atmos. Sci., 45, 2889–2919.
Battisti, D. S. and A. C. Hirst (1989): Interannual variability in a tropical atmosphere-ocean model: Influence of the basic state, ocean geometry and nonlinearity. J. Atmos. Sci., 46, 1687–1712.
Bjerknes, J. (1969): Atmospheric teleconections from the equatorial Pacific. Mon. Weather Rev., 97, 163–172.
Boulanger, J.-P. and C. Menkes (1995): Propagation and reflection of long equatorial waves in the Pacific Ocean during the 1992–1993 El Niño. J. Geophys. Res., 100, 25,041–25,059.
Enfield, D. B. (1987): The intraseasonal oscillation in eastern Pacific sea levels; How is it forced?. J. Phys. Oceanogr., 17, 1860–1876.
Geisler, J. E., M. L. Blackmon, G. T. Bates and S. Munoz (1985): Sensitivity of January climate response to the magnitude and position of equatorial Pacific sea surface temperature anomalies. J. Atmos. Sci., 42, 1037–1149.
Gill, A. E. (1975): Models of currents. p. 181–203. In Numerical Models of Ocean Circulation, Nat'l. Acad. Sci., Washington, D.C.
Hendon, H. H. and M. L. Salby (1995): The life cycle of the Madden-Julian Oscillation. J. Atmos. Sci., 51, 2225–2237.
Johnson, E. S. and M. J. McPhaden (1993): On the structure of intraseasonal Kelvin waves in the equatorial Pacific Ocean. J. Phys. Oceanogr., 23, 608–625.
Kalnay, E. et al. (1996): The NCEP/NCAR 40-year reanalysis project. Bull. Am. Meteorol. Soc., 77, 437–471.
Kessler, W. S. and R. Kleeman (2000): Rectification of the Madden-Julian Oscillation into the ENSO cycle. J. Clim. (in press).
Kessler, W. S. and M. J. McPhaden (1995a): The 1991–93 El Niño in the central Pacific. Deep-Sea Res. II, 42, 295–334.
Kessler, W. S. and M. J. McPhaden (1995b): Oceanic equatorial waves and the 1991–1993 El-Niño. J. Clim., 8, 1757–1774.
Kessler, W. S., M. J. McPhaden and K. M. Weickmann (1995): Forcing of Intraseasonal Kelvin waves in the equatorial Pacific. J. Geophys. Res., 100, 10,613–10,631.
Kutsuwada, K. and H. Inaba (1995): Long-range measurement of surface oceanic current in the western equatorial Pacific by acoustic doppler current profiler. J. Meteorol. Soc. Japan, 73(1), 1–11.
Latif, M., J. Biercamp and H. von Storch (1988): The response of a coupled ocean-atmosphere general circulation model to wind bursts. J. Atmos. Sci., 45, 964–979.
Levitus, S. and T. P. Boyer (1994): World Ocean Atlas 1994, Vol. 4, Temperature. NOAA Atlas NESDIS 3, U.S. Dept. of Commerece, Washington, D.C., 117 pp.
Levitus, S., R. Burgett and T. P. Boyer (1994): World Ocean Atlas 1994, Vol. 3, Salinity. NOAA Atlas NESDIS 3, U.S. Dept. of Commerece, Washington, D.C., 97 pp.
Madden, R. A. and P. R. Julian (1972): Description of global-scale circulation cells in the tropics with a 40–50 day period. J. Atmos. Sci., 29, 1109–1123.
McPhaden, M. J., A. J. Busalacchi, R. Cheney, J.-R. Donguy, K. S. Gage, D. Halpern, M. Ji, P. Julian, G. Meyers, G. T. Mitchum, P. P. Niiller, J. Picaut, R. W. Reynolds, N. Smith and K. Takeuchi (1998): The Tropical Ocean-Global Atmosphere observing system: A decade of progress. J. Geophys. Res., 103, 14,169–14,240.
Nakazawa, T. (1988): Tropical cloud clusters within the intraseasonal variations over the western Pacific. J. Meteorol. Soc. Japan, 66, 823–839.
Pacanowski, R. C. and S. G. H. Philander (1981): Parameterization of vertical mixing in numerical models of tropical oceans. J. Phys. Oceanogr., 11, 1443–1451.
Pacanowski, R. C., K. W. Dixon and A. Rosari (1991): The GFDL Modular Ocean Model Users Guide. GFDL Ocean Group Tech. Rep. No. 2.
Philander, S. G. H. and R. C. Pacanowski (1981): Response of equatorial oceans to periodic forcing. J. Geophys. Res., 86, 1903–1916.
Picaut, J. and T. Delcroix (1995): Equatorial wave sequence associated with warm pool displacements during the 1986–1989 El Niño-La Niña. J. Geophys. Res., 100, 18,393–18,408.
Picaut, J., M. Ioualalen, C. Menkes, T. Delcroix and M. J. McPhaden (1996): Mechanisms of the zonal displacements of the Pacific warm pool. Science, 274, 1486–1489.
Ralph, E. A., K. Bi, P. P. Niiler and Y. du Penhoat (1997): A Lagrangian description of the western equatorial Pacific response to the wind burst of December 1992. J. Clim., 10, 1706–1721.
Robinson, A. R. (1966): An investigation into the wind as the cause of the equatorial undercurrent. J. Mar. Res., 24, 179–204.
Rui, H. and B. Wang (1990): Development characteristics and dynamic structure of tropical intraseasonal convection anomalies. J. Atmos. Sci., 47, 357–379.
Schopf, P. S. and M. J. Suarez (1988): Vacillations in a coupled ocean-atmosphere model. J. Atmos. Sci., 45, 549–566.
Sui, C.-H. and K.-M. Lau (1992): Multi-scale phenomena in the tropical atmosphere over the western Pacific. Mon. Weather Rev., 120, 407–430.
Yoshida, K. (1959): A theory of the Cromwell Current and equatorial upwelling. J. Oceanogr. Soc. Japan, 15, 154–170.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Suzuki, T., Takeuchi, K. Response of Equatorial Pacific Mean Temperature Field to Intraseasonal Wind Forcing. Journal of Oceanography 56, 485–494 (2000). https://doi.org/10.1023/A:1011140708962
Issue Date:
DOI: https://doi.org/10.1023/A:1011140708962