The Principal Physical Modes of Variability over the Tropical Pacific

Abstract The structures of the two principal modes of sea surface temperature (SST) variability were extracted by conducting cyclostationary EOF (CSEOF) analysis and regression analysis on several key variables. The CSEOF analysis extracts two dominant modes of SST variability that are distinct in nature. The first CSEOF is stochastic in nature and represents a standing mode of SST variability associated with a basinwide change in the surface wind. The second CSEOF exhibits a strong deterministic component describing a biennial oscillation between a warm phase and a cold phase. The surface wind directional change in the far-western Pacific appears to be instrumental for the oscillation between the two phases. Because of the distinct nature of evolution, dynamical and thermodynamical responses of the two modes are different. Further, the predictability of the two modes is different. Specifically, the biennial mode is more predictable because of the strong deterministic component associated with its evoluti...

[1]  R. Weisberg,et al.  The 1997–98 El Niño Evolution Relative to Previous El Niño Events , 2000 .

[2]  A. J. Clarke,et al.  Quasi‐biennial winds in the far western equatorial Pacific phase‐Locking El Niño to the seasonal cycle , 2000 .

[3]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[4]  B. Hoskins,et al.  Diagnostics of the Global Atmospheric Circulation Based on ECMWF analyses 1979-1989 , 1989 .

[5]  James A. Carton,et al.  A Simple Ocean Data Assimilation Analysis of the Global Upper Ocean 1950–95. Part I: Methodology , 2000 .

[6]  J. Carton,et al.  Interannual and Decadal Variability in the Tropical and Midlatitude Pacific Ocean , 1999 .

[7]  A. J. Clarke,et al.  The Connection between the Boreal Spring Southern Oscillation Persistence Barrier and Biennial Variability , 1999 .

[8]  J. Bjerknes.  ATMOSPHERIC TELECONNECTIONS FROM THE EQUATORIAL PACIFIC1 , 1969 .

[9]  P. Xie,et al.  Global Precipitation: A 17-Year Monthly Analysis Based on Gauge Observations, Satellite Estimates, and Numerical Model Outputs , 1997 .

[10]  Michael J. McPhaden,et al.  Equatorial waves and the 1997–98 El Niño , 1999 .

[11]  J. Boulanger,et al.  Propagation and reflection of long equatorial waves in the Pacific Ocean during the 1992–1993 El Niño , 1995 .

[12]  Chul Eddy Chung,et al.  On the evolution of the annual cycle in the tropical Pacific , 2001 .

[13]  Allan J. Clarke,et al.  ENSO prediction using an ENSO trigger and a proxy for Western Equatorial Pacific Warm Pool Movement , 2001 .

[14]  Ralph J. Slutz,et al.  A Comprehensive Ocean-Atmosphere Data Set , 1987 .

[15]  E. Rasmusson,et al.  The biennial component of ENSO variability , 1990 .

[16]  N. Sato,et al.  Recent abnormal changes in wintertime atmospheric response to tropical SST forcing , 1997 .

[17]  Peter J. Webster,et al.  The annual cycle of persistence in the El Nño/Southern Oscillation , 1998 .

[18]  J. Wallace,et al.  A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production , 1997 .

[19]  Kwang-Yul Kim,et al.  Investigation of ENSO variability using cyclostationary EOFs of observational data , 2002 .

[20]  T. Barnett,et al.  Interdecadal interactions between the tropics and midlatitudes in the Pacific Basin , 1999 .

[21]  J. Boulanger,et al.  Long equatorial wave reflection in the Pacific Ocean from TOPEX/POSEIDON data during the 1992–1998 period , 1999 .

[22]  J. Wallace,et al.  ENSO-like Interdecadal Variability: 1900–93 , 1997 .

[23]  J. Weiss,et al.  Quantifying persistence in ENSO , 1999 .

[24]  R. Weisberg,et al.  A Western Pacific Oscillator Paradigm for the El Niño‐Southern Oscillation , 1997 .

[25]  T. Barnett,et al.  Origins of the midlatitude Pacific decadal variability , 1999 .

[26]  John M. Wallace,et al.  The Signature of ENSO in Global Temperature and Precipitation Fields Derived from the Microwave Sounding Unit , 1994 .

[27]  M. Mcphaden,et al.  Genesis and evolution of the 1997-98 El Nino , 1999, Science.

[28]  Ming Ji,et al.  An Improved Coupled Model for ENSO Prediction and Implications for Ocean Initialization. Part I: The Ocean Data Assimilation System , 1998 .

[29]  James A. Carton,et al.  A Simple Ocean Data Assimilation Analysis of the Global Upper Ocean 1950-95. Part II: Results , 2000 .

[30]  A. J. Clarke.  Why are surface equatorial ENSO winds anomalously westerly under anomalous large-scale convection? , 1994 .

[31]  kwang-yul kim,et al.  EOFs of Harmonizable Cyclostationary Processes , 1997 .

[32]  NOTES AND CORRESPONDENCE Comments on ''The Connection between the Boreal Spring Southern Oscillation Persistence Barrier and Biennial Variability'' , 2000 .