An empirical model for the temperature of subsurface water entrained into the ocean mixed layer (T-e) is presented and evaluated to improve sea Surface temperature anomaly (SSTA) simulations in an intermediate ocean model (IOM) of the tropical Pacific. An inverse modeling approach is adopted to estimate T-e from an SSTA equation using observed SST and simulated Upper-ocean currents. A relationship between T-e and sea surface height (SSH) anomalies is then obtained by utilizing a singular value decomposition (SVD) of their covariance. This empirical scheme is able to better parameterize T-e anomalies than other local schemes and quite realistically depicts interannual variability of T-e, including a nonlocal phase lag relation of T-e variations relative to SSH anomalies over the central equatorial Pacific. An improved T-e parameterization naturally leads to better depiction of the subsurface effect on SST variability by the mean upwelling of subsurface temperature anomalies. As a result, SSTA simulations are significantly improved in the equatorial Pacific a comparison with other schemes indicates that systematic errors of the simulated SSTAs are significantly small-apparently due to the optimized empirical T-e parameterization. Cross validation and comparisons with other model simulations are made to illustrate the robustness and effectiveness of the scheme. In particular it is demonstrated that the empirical T-e model constructed from one historical period can be successfully used to improve SSTA simulations in another.
899JYTimes Cited:9Cited References Count:47