Tropical Climate Response to Tidal Mixing in the Eastern Pacific

Abstract

Response of the equatorial climate to the tidal mixing is investigated using a coupled climate model and an ocean stand-alone model. To parameterizethe tidal mixing, the vertical mixing coefficient was introduced to the background from the tidal velocity and bottom roughness following Jayne and St.Laurent (2001). The tidal mixing increases the sea surface temperature especially in the eastern tropical Pacific as well as deepens the thermoclineover the whole tropical Pacific. In particular, the deepening of the thermocline deceases the ENSO variability, which has been over-simulated in theclimate models, by ~9% for NINO3.4 and ~17% for NINO4. In addition, the ocean stand-alone model shows that the tidal mixing generates the warmanomaly near the eastern coast of the tropical Pacific to propagate westward along the thermocline depth of the off-equator. As a result, thethermocline depth deepens by ~10m along the equator. Consequently, it is shown that the tidal mixing takes an effect to the climate variability in thetropical Pacific through the oceanic response.e tidal velocity and bottom roughness following Jayne and St.Laurent (2001). The tidal mixing increases the sea surface temperature especially in the eastern tropical Pacific as well as deepens the thermoclineover the whole tropical Pacific. In particular, the deepening of the thermocline deceases the ENSO variability, which has been over-simulated in theclimate models, by ~9% for NINO3.4 and ~17% for NINO4. In addition, the ocean stand-alone model shows that the tidal mixing generates the warmanomaly near the eastern coast of the tropical Pacific to propagate westward along the thermocline depth of the off-equator. As a result, thethermocline depth deepens by ~10m along the equator. Consequently, it is shown that the tidal mixing takes an effect to the climate variability in thetropical Pacific through the oceanic response.