thermocline

Layer in thermally stratified body of water in which the temperature gradient is at a maximum. (ISO/6107)

Partie d'une masse d'eau stratifiée pour laquelle le gradient de température atteint un maximum.

The layer of maximum vertical temperature gradient in the ocean, lying between the surface ocean and the abyssal ocean. In subtropical regions, its source waters are typically surface waters at higher latitudes that have subducted and moved equatorward. At high latitudes, it is sometimes absent, replaced by a halocline, which is a layer of maximum vertical salinity gradient.