Vertical salinity gradient
When salinity of surface waters differ from that that of underlying waters, usually have a zone in which salinity changes rapidly with depth
Steep salinity gradient = the halocline zone (or halocline)
- Haloclines common in the tropics, where low-salinity surface water sits on moderate salinity deep water
- Haloclines common in subtropics, where high salinity surface waters sits on moderate salinity deep water
- Haloclines occur seasonally in mid latitudes, when precipitation creates low salinity surface waters
Haloclines may give rise to pycnocline