CMIP6 model sea surface temperature (SST) seasonal extrema averaged over
1980-2010 are assessed against the World Ocean Atlas (WOA18)
observational climatology. The biases in SST seasonal extrema are
largely consistent with the annual mean SST biases. However, the
amplitude and spatial pattern of SST bias vary seasonally in the 20
CMIP6 models assessed. Large seasonal variations in the SST bias occur
in eastern boundary upwelling regions and polar regions, and the eastern
equatorial Atlantic. These results demonstrate the importance of
evaluating model performance not simply against annual mean properties.
Models with greater vertical resolution in their ocean component
typically demonstrate better representation of SST extrema, particularly
seasonal maximum SST. No significant relationship with horizontal ocean
model resolution is found.