How Much of Subsurface Temperature Variability in the Equatorial Pacific Can Be Recovered by the Surface Fluxes?

Subsurface temperature variability in ocean analysis products can be attributed to three factors: (1) Assimilation of ocean data; (2) contribution from specification of SST; and (3) surface fluxes. The focus of this study is to investigate the question without data assimilation, how much of subsurface temperature variability in the equatorial Pacific can be recovered by the surface fluxes .VS. SST specification. In the context El Niño prediction, this study shed light on the issue of what additional components of the ocean observation system may be crucial for skillful ENSO predictions. A set of ocean-alone simulations driven by different surface flux component and coupled model simulations with strong nudging to observe SST were conducted. Surface wind in response to SST restoring is sufficient to recover the subsurface temperature variations in the western-central equatorial Pacific, while temperature variation in the eastern Pacific depends heavily on surface wind.