Mixed layer: ho(cid:373)oge(cid:374)eous layer at the o(cid:272)ea(cid:374)"s surfa(cid:272)e (cid:449)ithi(cid:374) (cid:449)hi(cid:272)h o(cid:272)ea(cid:374)i(cid:272) properties temperature or salinity change very little: mixed layers vary over the course of the year. Subduction: the seasonal cycle of the mixed layer allows surface waters to be taken up into the interior of the ocean. Factors that control depth of the mixed layer: wind driven mixing, stability of underlying water, surface buoyancy changes. Heating & river runoff which acts to stratify fluid. Cooling & tidal wind mixing which acts to mix fluid vertically. Heating > mixing = water column stratifies in summer. Heating < mixing = water column remains vertically mixed. ** the mixed layer is deepest where the density is the thickest and the temperature is the coldest. Water density: density if dependent on temperature, salinity, and pressure, pressure: water molecules are close together in liquid form it is difficult to squeeze them closer together as pressure increases.