A Mechanistic Analysis of Tropical Pacific Dynamic Sea Level in GFDL-OM4 under OMIP-I and OMIP-II Forcings

The sea level over the tropical Pacific is a key indicator reflecting vertically integrated heat distribution over the ocean. Here, we use the Geophysical Fluid Dynamics Laboratory global ocean–sea ice model (GFDL-OM4) forced by both the Coordinated Ocean-Ice Reference Experiment (CORE) and Japanese 55-year Reanalysis (JRA-55)-based surface dataset for driving ocean–sea ice models (JRA55-do) atmospheric states (Ocean Model Intercomparison Project (OMIP) versions I and II) to evaluate the model performance and biases compared against available observations. We find persisting mean state dynamic sea level (DSL) bias along 9 N even with updated wind forcing in JRA55-do relative to CORE. The mean state bias is related to biases in wind stress forcing and geostrophic currents in the 4 to 9 N latitudinal band. The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE. In the CORE forcing, the anomalous westerly wind trend in the eastern tropical Pacific causes an underestimated DSL trend across the entire Pacific basin along 10 N. The simulation forced by JRA55-do significantly reduces the bias in DSL trend over the northern tropical Pacific relative to CORE. We also identify a bias in the easterly wind trend along 20 N in both JRA55-do and CORE, thus motivating future improvement. In JRA55-do, an accurate Rossby wave initiated in the eastern tropical Pacific at seasonal timescale corrects a biased seasonal variability of the northern equatorial countercurrent in the CORE simulation. Both CORE and JRA55-do generate realistic DSL variation during El Niño. We find an asymmetry in the DSL pattern on two sides of the Equator is strongly related to wind stress curl that follows the sea level pressure evolution during El Niño.

[1]  R. Steven Nerem,et al.  Investigating the Acceleration of Regional Sea Level Rise During the Satellite Altimeter Era , 2020, Geophysical Research Letters.

[2]  G. Danabasoglu,et al.  Evaluation of global ocean–sea-ice model simulations based on the experimental protocols of the Ocean Model Intercomparison Project phase 2 (OMIP-2) , 2020, Geoscientific Model Development.

[3]  Chris Blanton,et al.  The GFDL Global Ocean and Sea Ice Model OM4.0: Model Description and Simulation Features , 2019, Journal of Advances in Modeling Earth Systems.

[4]  J. Gregory,et al.  Concepts and Terminology for Sea Level: Mean, Variability and Change, Both Local and Global , 2019, Surveys in Geophysics.

[5]  M. England,et al.  Reply to “Comments on ‘Diathermal Heat Transport in a Global Ocean Model’” , 2019, Journal of Physical Oceanography.

[6]  S. Griffies,et al.  Surface winds from atmospheric reanalysis lead to contrasting oceanic forcing and coastal upwelling patterns , 2019, Ocean Modelling.

[7]  S. Griffies,et al.  Understanding the Equatorial Pacific Cold Tongue Time-Mean Heat Budget. Part I: Diagnostic Framework , 2018, Journal of Climate.

[8]  G. Danabasoglu,et al.  JRA-55 based surface dataset for driving ocean–sea-ice models (JRA55-do) , 2018, Ocean Modelling.

[9]  Martina Stockhause,et al.  input4MIPs: Making [CMIP] model forcing more transparent , 2017 .

[10]  F. Chai,et al.  Variability of the Pacific North Equatorial Current from 1993 to 2012 based on a 1/8° Pacific model simulation , 2017 .

[11]  Patrick Heimbach,et al.  OMIP contribution to CMIP6: experimental and diagnostic protocol for the physical component of the Ocean Model Intercomparison Project , 2016 .

[12]  F. Landerer,et al.  Pacific sea level rise patterns and global surface temperature variability , 2016 .

[13]  B. Samuels,et al.  North and equatorial Pacific Ocean circulation in the CORE-II hindcast simulations , 2016 .

[14]  Veronika Eyring,et al.  Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization , 2015 .

[15]  F. Roquet,et al.  Accurate polynomial expressions for the density and specific volume of seawater using the TEOS-10 standard , 2015 .

[16]  D. Hu,et al.  Variability of the Pacific North Equatorial Current from repeated shipboard acoustic Doppler current profiler measurements , 2014, Journal of Oceanography.

[17]  kwang-yul kim,et al.  Uncovering an anthropogenic sea-level rise signal in the Pacific Ocean , 2014 .

[18]  B. Samuels,et al.  An assessment of global and regional sea level for years 1993-2007 in a suite of interannual CORE-II simulations , 2014 .

[19]  Nick Rayner,et al.  EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates , 2013 .

[20]  M. England,et al.  Constraining Wind Stress Products with Sea Surface Height Observations and Implications for Pacific Ocean Sea Level Trend Attribution , 2012 .

[21]  Xuebin Zhang,et al.  Sea level trends, interannual and decadal variability in the Pacific Ocean , 2012 .

[22]  Model simulation , 2012 .

[23]  M. Merrifield.  A Shift in Western Tropical Pacific Sea Level Trends during the 1990s , 2011 .

[24]  A. Miller,et al.  Dynamical suppression of sea level rise along the Pacific coast of North America: Indications for imminent acceleration , 2011 .

[25]  Shang-Ping Xie,et al.  Wave- and Anemometer-Based Sea Surface Wind (WASWind) for Climate Change Analysis* , 2010 .

[26]  Stephen G. Yeager,et al.  The global climatology of an interannually varying air–sea flux data set , 2009 .

[27]  Frank O. Bryan,et al.  Coordinated Ocean-ice Reference Experiments (COREs) , 2009 .

[28]  C. Wunsch,et al.  The mean seasonal cycle in sea level estimated from a data‐constrained general circulation model , 2008 .

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

[30]  Eric P. Chassignet,et al.  North Atlantic Simulations with the Hybrid Coordinate Ocean Model (HYCOM): Impact of the Vertical Coordinate Choice, Reference Pressure, and Thermobaricity , 2003 .

[31]  K. Trenberth,et al.  Evolution of El Niño–Southern Oscillation and global atmospheric surface temperatures , 2002 .

[32]  Gregory C. Johnson,et al.  Direct measurements of upper ocean currents and water properties across the tropical Pacific during the 1990s , 2002 .

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

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

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

[36]  Fei-Fei Jin,et al.  An Equatorial Ocean Recharge Paradigm for ENSO. Part II: A Stripped-Down Coupled Model , 1997 .

[37]  G. Mellor.  Introduction to physical oceanography , 1996 .

[38]  John M. Wallace,et al.  Large-scale atmospheric circulation features of warm and cold episodes in the tropical Pacific , 1990 .

[39]  Mark A. Johnson,et al.  The role of coastal Kelvin waves on the northeast Pacific Ocean , 1990 .

[40]  J. Picaut,et al.  Observations and wind-forced model simulations of the mean seasonal cycle in tropical Pacific sea surface topography , 1988 .

[41]  Antonio J. Busalacchi,et al.  Hindcasts of Sea Level Variations during the 1982-83 El Nino , 1985 .

[42]  Mark A. Cane,et al.  Modeling Sea Level During El Niño , 1984 .

[43]  Liu Xinwu.  This is How the Discussion Started , 1981 .

[44]  G. Meyers.  On the Annual Rossby Wave in the Tropical North Pacific Ocean , 1979 .

[45]  K. Wyrtki.  Sea Level and the Seasonal Fluctuations of the Equatorial Currents in the Western Pacific Ocean , 1974 .

[46]  A. E. Gill,et al.  The theory of the seasonal variability in the ocean , 1973 .