NUMERICAL EXPERIMENTS ON THE PREDICTION OF SEA-SURFACE TEMPERATURE ANOMALIES IN THE GULF-OF-MEXICO

The conservation of thermal energy equation applied to the mixed layer of the ocean, has been used to predict the sea surface temperature an omalies (SSTA) and the month-to-month changes in the Gulf of Mexico. T he model includes the horizontal transport of heat by mean ocean curre nts and by turbulent eddies, as well as the heating by short and long wave radiation, evaporation and sensible heat given off to the atmosph ere. A comparative study is carried out on the relative importance of the heating and transport terms. An objective verification of the skil l of the predictions is presented for each season and for the whole pe riod from March 1986 to February 1987. The predictions using only the heating terms have some skill over the control predictions (persistenc e and return to normal). The skill is substantially increased when the horizontal transport of heat by turbulent mixing is included in the m odel. The incorporation in the model of the Ekman wind drift current a nomalies computed from the anomalous surface geostrophic wind improves appreciably the skill of the predictions in winter and fall. The mixe d layer depth computed using the Kraus and Turner theory with dissipat ion, shows that the depths in summer and fall are shallower than in sp ring and winter. The effect of the shallow mixed layer depth in the mo del becomes apparent in summer and fall, improving the skill of the pr edictions in these seasons, with respect to the skill obtained using a constant mixed layer depth of 60 m. The incorporation in the model of the cooling in the mixed layer by turbulent entrainment of colder wat er from the thermocline, does not improve in an appreciable way the av erage skill of the predictions. (C) 1997 Elsevier Science B.V.