Whit Anderson, UCAR/NOAA/GFDL
A bio-optical parameterization for short-wave radiation penetration is applied to a fully coupled general circulation model (HCM2). The parameterization is based on the Manizza scheme which uses surface chlorophyll-a concentrations to determine the oceanic e-folding depth of short-wave radiation. Experiments are run using Sea-WiFS chlorophyll-a climatology (green-run) and with chlorophyll-a concentrations set to zero (blue-run). Comparison of the experiments show that in regions where chlorophyll is present (in the Sea-WiFS climatology), the zero chlorophyll experiment produces deeper short-wave penetration. This results in an increase of mixing up of sub-mixed layer water, a deeper mixed-layer depth and cooler sea surface temperatures (SST). This behavior is not shown in the eastern equatorial Pacific. The zero chlorophyll experiment shows warmer SST with no change in mixed-layer depth. The 100 year mean of the blue-run ocean and atmosphere exhibits characteristics of a strong El Nino. This poster explores the possible mechanisms.