Mechanisms Controlling the Interannual Variation of Mixed Layer Temperature Averaged over the Niño-3 Region

Abstract Processes controlling the interannual variation of mixed layer temperature (MLT) averaged over the Nino-3 domain (5°N–5°S, 150°–90°W) are studied using an ocean data assimilation product that covers the period of 1993–2003. The overall balance is such that surface heat flux opposes the MLT change but horizontal advection and subsurface processes assist the change. Advective tendencies are estimated here as the temperature fluxes through the domain’s boundaries, with the boundary temperature referenced to the domain-averaged temperature to remove the dependence on temperature scale. This allows the authors to characterize external advective processes that warm or cool the water within the domain as a whole. The zonal advective tendency is caused primarily by large-scale advection of warm-pool water through the western boundary of the domain. The meridional advective tendency is contributed to mostly by Ekman current advecting large-scale temperature anomalies through the southern boundary of the d...

[1]  W. Large,et al.  Oceanic vertical mixing: a review and a model with a nonlocal boundary layer parameterization , 1994 .

[2]  Dimitris Menemenlis,et al.  Effects of the Indonesian Throughflow on the Pacific and Indian Oceans , 2002 .

[3]  D. Hansen,et al.  Genesis and effects of long waves in the equatorial Pacific , 1984 .

[4]  J. S. Godfrey,et al.  Interannual Dynamics and Thermodynamics of the Indo–Pacific Oceans , 2000 .

[5]  Ichiro Fukumori,et al.  A Partitioned Kalman Filter and Smoother , 2002 .

[6]  P. Malanotte‐Rizzoli,et al.  The Impact of Horizontal Resolution on the Tropical Heat Budget in an Atlantic Ocean Model , 2005 .

[7]  Ichiro Fukumori,et al.  Assimilation of TOPEX/Poseidon altimeter data into a global ocean circulation model: How good are the results? , 1999 .

[8]  P. Gent,et al.  Isopycnal mixing in ocean circulation models , 1990 .

[9]  G. Madec,et al.  A Modeling Study of the Impact of Tropical Instability Waves on the Heat Budget of the Eastern Equatorial Pacific , 2006 .

[10]  Dake Chen,et al.  The annual cycle of SST in the Eastern Tropical Pacific, diagnosed in an ocean GCM , 1998 .

[11]  W. Kessler.  The circulation of the eastern tropical Pacific: A review , 2006 .

[12]  Victoria J. Coles,et al.  North Pacific Subtropical–Tropical Gyre Exchanges in the Thermocline: Simulations with Two Isopycnic OGCMs , 2001 .

[13]  Ichiro Fukumori,et al.  The 1997–1999 abrupt change of the upper ocean temperature in the north central Pacific , 2004 .

[14]  E. Guilyardi,et al.  A Model Study of Oceanic Mechanisms Affecting Equatorial Pacific Sea Surface Temperature during the 1997–98 El Niño , 2001 .

[15]  P. Delecluse,et al.  An OGCM Study for the TOGA Decade. Part I: Role of Salinity in the Physics of the Western Pacific Fresh Pool , 1998 .

[16]  M. Cox.  Generation and Propagation of 30-Day Waves in a Numerical Model of the Pacific , 1980 .

[17]  B. Qiu.  The Kuroshio Extension System: Its Large-Scale Variability and Role in the Midlatitude Ocean-Atmosphere Interaction , 2002 .

[18]  Ichiro Fukumori,et al.  What Is Data Assimilation Really Solving, and How Is the Calculation Actually Done? , 2006 .

[19]  S. Levitus,et al.  Objective analyses of temperature and salinity for the world ocean on a 1/4° grid , 1997 .

[20]  Antonio J. Busalacchi,et al.  Tropical instability waves in the Atlantic Ocean , 2004 .

[21]  Temperature Advection: Internal versus External Processes , 2004 .

[22]  M. Mcphaden.  Evolution of the 2002/03 El Niño* , 2003 .

[23]  J. Picaut,et al.  An Advective-Reflective Conceptual Model for the Oscillatory Nature of the ENSO , 1997 .

[24]  Roger Lukas,et al.  The mixed layer of the western equatorial Pacific Ocean , 1991 .

[25]  H. Bryden,et al.  Diagnostic Model of the Three-Dimensional Circulation in the Upper Equatorial Pacific Ocean , 1985 .

[26]  Fei-Fei Jin,et al.  An Equatorial Ocean Recharge Paradigm for ENSO. Part I: Conceptual Model , 1997 .

[27]  D. Halpern,et al.  Observations of 20-Day Period Meridional Current Oscillations in the Upper Ocean along the Pacific Equator , 1988 .

[28]  L. Perelman,et al.  Hydrostatic, quasi‐hydrostatic, and nonhydrostatic ocean modeling , 1997 .

[29]  M. Mcphaden,et al.  Surface Layer Temperature Balance in the Equatorial Pacific during the 1997-98 El Nino and 1998-99 La Nina * , 2001 .

[30]  K. Wyrtki,et al.  El Niño—The Dynamic Response of the Equatorial Pacific Oceanto Atmospheric Forcing , 1975 .

[31]  M. Cane,et al.  A Model El Niñ–Southern Oscillation , 1987 .

[32]  M. Mcphaden,et al.  Vertical Velocities and Transports in the Equatorial Pacific during 1993–99* , 2001 .

[33]  P. Richardson,et al.  Observations of the Mindanao Current during the western equatorial Pacific Ocean circulation study , 1991 .

[34]  S. P. Hayes,et al.  Variability of the sea surface temperature in the eastern equatorial Pacific during 1986–1988 , 1991 .

[35]  Patrick Marchesiello,et al.  Thermal forcing for a global ocean circulation model using a three-year climatology of ECMWF analyses , 1995 .

[36]  M. Mcphaden,et al.  The Surface-Layer Heat Balance in the Equatorial Pacific Ocean. Part I: Mean Seasonal Cycle* , 1999 .

[37]  Tong Lee,et al.  The Closure of the Ocean Mixed Layer Temperature Budget using Level-Coordinate Model Fields , 2006 .

[38]  Max J. Suarez,et al.  Vacillations in a Coupled Ocean–Atmosphere Model , 1988 .