How Wind and Stratification Control Upper-Ocean Mixing A. Natarov1, K. Richards1, Y. Kashino2 1IPRC, 2JAMSTEC Top: Southern oscillation index. Negative (positive) values correspond to El Niño (La Niña) events. Bottom: Observed stratification in the western equatorial Pacific during SURTROPAC. Depth profiles of the horizontally averaged vertical mixing coefficient from the four numerical experiments. Latitudinal structure of the vertical mixing coefficient averaged between 150 and 300 meter depths from the four numerical experiments. ENSO modulates upper ocean stratification in the Western Equatorial Pacific (left panel). Recent microstructure measurements carried out by IPRC and JAMSTEC scientists indicate that ENSO may also control mixing. Specifically, they discovered that the 2010 La Niña was accompanied by much higher mixing levels than the 2009 El Niño even though the wind bursts were more intense during the El Niño year. To further investigate the dependence of mixing on wind intensity and stratification, the scientists used high resolution Regional Ocean Modeling System (ROMS) to conduct four numerical experiments: {weak (w), strong (s)} x {wind stress (τ), stratification (N)} = {wτ&sN, …}. They found that the level of mixing is controlled by stratification in the thermocline and by the wind intensity above the thermocline (middle panel). Moreover, the meridional extent of the region of enhanced mixing depends on both wind intensity and stratification (right panel). These findings will help to understand and quantify processes that generate mixing in the upper Western Equatorial Pacific ocean and so to improve ocean and climate models.