OCE 96-18102 Tandon The project will evaluate the contribution of diurnal and seasonal cycling of the mixed layer to the transformation of water masses in the upper ocean. This represents an extension of the steady thermodynamic balance where the air- sea buoyancy flux is compensated by vertical mixing in the surface mixed layer and the advective buoyancy flux. In this study the diapycnal flux due to time-dependent (diurnal and seasonal) mixed layer deepening and entrainment will be quantified. Both data analysis and diagnostic studies of model output will be used in the investigation.