[A-CG43] Multi-scale ocean-atmosphere interaction in the tropics

[ACG43-P04] Interannual variations of simulated deep cycle turbulence in the eastern equatorial Pacific

*Rintaro NAKANO¹, Tomoki Tozuka¹ (1.The University of Tokyo)

Keywords:turbulent mixing, equatorial Pacific, ENSO

In the equatorial region, turbulence in the upper ocean exhibits a vertical cycle along solar radiation known as “deep cycle (DC)”. Since DC can affect large-scale phenomena, such as the El Niño/Southern Oscillation (ENSO), through vertical mixing, studying DC is important to understand the mechanisms of ENSO and the climate system. However, the interannual variations of DC remain largely unexplored, partly due to limited observations. In this study, this DC turbulence (DCT) is simulated using a regional ocean model, and its descent rates are compared between a normal year and ENSO periods. Although the simulated descent rates are generally slower than those observed in previous studies, likely due to model biases in representing vertical structures of temperature and current, the results show that the rates are faster in a normal year compared to El Niño and La Niña years. This difference appears to depend on the magnitudes of monthly averages of wind stress. Short-term differences in wind are found to be a more influential factor on DCT.