Thermocline

THE THERMOCLINE IS the region of the ocean where temperature decreases most rapidly with increasing depth. It separates the warm, well-mixed upper layer from the colder, deep water below. A thermocline is present throughout the year in the tropics and middle latitudes. It is more difficult to discern in high latitudes, where temperature is more uniform with depth. The presence of a very shallow thermocline in the eastern equatorial Pacific Ocean has important implications for global climate.

The thermocline exists because the ocean absorbs most of the sun's heat in a shallow layer near the surface. The heat absorbed from the sun increases the temperature of the surface relative to that of the deep ocean, maintaining the thermocline. This is in contrast to the atmosphere, where ...