1. Thermohaline circulation

2. Circulation of water-due to water density-induced by temperature and salinity
Generated by density differences between water masser and result in Horizontal and vertical flow
Density of water increases as it becomes cooler and more saline
It sinks to a level below which all water are more dense and above it are lessdense.
In sup polar and polar region- cold dense water descends and flows towards equator-They mix with adjacent water mass and loose indenting
In tropical region: Excess evaporation-produce dense saline water-sink-to appropriate density level. Eg: Mediterranean sea
In estuaries-As river flows in to estuary the less dense freshwater forms-a wedge that displaces denser seawater-and the wedge thins seaward as the freshwater spreads outwards and slowly mixes with seawater.