Vertical Mixing in the Equatorial Pacific along 150°W in March 1988

Abstract

A meridional transect along 150°W in March 1988 revealed a statistically significant maximum in turbulent kinetic energy dissipation, ? at 1°S?0° between 40-m and 60-m depth. The wind stress and buoyancy flux were poorly correlated with the observed mixed layer dissipation measured below 10 m. Dissipation modeled using similarity scaling was larger than the observed mixed layer dissipation (below 10 m) away from the equator and smaller than observed at 0°. The ratio of observed and modeled dissipation at the equator was highly correlated to the vertical velocity shear at the base of the mixed layer. The turbulent stress divergence computed as the residual of annual mean terms between 0 and 60 m for the 41/2-day time series was close to the sum of the annual mean terms of the zonal momentum balance of Bryden and Brady. For 21/2 days at 0° the change in heat content of the top 15 m was consistent with the observed one-dimensional fluxes within the uncertainty of the measurements. The 4-day average of penetrative irradiance out of the layer was twice as large as that of the turbulent heat flux.