Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling
01 December 2016

Challenges and Prospects for Reducing Coupled Climate Model SST biases in the Eastern Tropical Atlantic and Pacific Oceans


Well-known problems trouble climate models in the eastern Atlantic and Pacific ocean basins. Model climates are too symmetric about the equator. Model SST is too warm south and southeast of the equator and there is too much rain in a band south of the equator. Near-coastal eastern equatorial SST is too warm, producing a zonal SST gradient in the Atlantic opposite in sign to that observed. 




The U.S. CLIVAR Working Group on Eastern Tropical Ocean Synthesis has pursued an updated assessment of coupled model SST biases, focusing on the surface energy balance components, on regional error sources from clouds, deep convection, winds and ocean eddies, on the sensitivity to model resolution, and on remote impacts.


Motivated by the assessment, the WG makes the following recommendations: 1) encourage identification of the specific parameterizations contributing to the biases in individual models, as these can be model-dependent, 2) restrict multimodel intercomparisons to specific processes, 3) encourage development of high-resolution coupled models with a concurrent emphasis on parameterization development of finer-scale ocean and atmosphere features, including low clouds, 4) encourage further availability of all surface flux components from buoys, for longer continuous time periods, in persistently cloudy regions, and 5) focus on the eastern basin coastal oceanic upwelling regions, where further opportunities for observational-modeling synergism exist.



Brian Medeiros
National Center for Atmospheric Research (NCAR)