SST anomaly averaged over the global tropics (10S-10N) for the period of
1982-2004. The black, red and yellow lines represent the
observations (OI SSTs), the ensemble mean of CFS 1-month lead
forecasts and the individual members of the CFS forecasts,
respectively. It is obvious that in the earlier period (1982-1990),
the CFS forecasted SSTs are warmer than the observed, while in the
later period the situation is reversed.