The role of surface shortwave flux correction in reducing climatological temperature biases

Coupled ocean-atmosphere climate models suffer from a number of climatological biases in sea surface temperature (SST) such as the cold tongue bias in the tropical Pacific and warm biases along eastern subtropical ocean boundaries. The exact causes of these biases are often difficult to diagnose given the strong coupled ocean-atmosphere interactions underpinning the seasonal cycle within these regions. Here, we investigate the possibility of reducing these biases within both low and high resolution versions of a fully coupled climate model (CESM) by globally (and regionally) correcting the net shortwave flux at the surface towards values derived from Clouds and Earth's Radiant Energy Systems (CERES)-Energy Balanced And Filled (EBAF) climatological estimates. This approach reduces the global mean SST bias. While the SST biases are improved in several regions, such as the northern hemisphere subtropical gyres and Pacific cold tongue, biases in other regions such as the Southern Ocean persist. The persistence of these biases despite corrected shortwave forcing potentially point to shortcomings in the representation of surface mixed-layer processes by the ocean component.