The term halothermal circulation refers to the part of the large-scale ocean circulation that is driven by global

density gradient Density gradient is a spatial variation in density over an area. The term is used in the natural sciences to describe varying density of matter, but can apply to any quantity whose density can be measured. Aerodynamics In the study of supersonic ...

s created by surface heat and evaporation.'' The adjective halothermal derives from '' halo-'' referring to salt content and '' -thermal'' referring to temperature, factors which together determine the density of sea water. Halothermal circulation is driven primarily by salinity changes and secondarily by temperature changes (as opposed to the

thermohaline Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective ''thermohaline'' derives from '' thermo-'' referring to tempe ...

mode in modern oceans). The generation of high salinity surface waters at low latitudes, which were therefore of higher density and thus sank, is thought to have been the dominant ocean circulation driver during greenhouse climates such as the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. Similar dynamics operate today in the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western Europe, Western and Southern Europe and Anatolia, on the south by North Africa ...

. The formation of bottom waters by halothermal dynamics is considered to be one to two orders of magnitude weaker than in thermohaline systems.

References

* Kennett, J.P. & Stott, L.D., 1990, Proteus and Proto-Oceanus, Paleogene oceans as revealed from Antarctic stable isotope results, ODP Leg 113. ''Proceedings Ocean Drilling Program, Science Results'' 113, 865–880. Physical oceanography Geological processes {{ocean-stub