A thermostad is a homogeneous layer of oceanic waters in terms of temperature, it is defined as a relative minimum of the vertical

temperature gradient A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature spatial gradient is a vector quantity with Dimensional analysis, ...

. The term was coined in 1966 by R. Carlton Seitz, at the time at the Chesapeake Bay Institute of

Johns Hopkins University The Johns Hopkins University (often abbreviated as Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland, United States. Founded in 1876 based on the European research institution model, J ...

. He proposed it as in opposition to a

thermocline A thermocline (also known as the thermal layer or the metalimnion in lakes) is a distinct layer based on temperature within a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) with a high gradient of distinct te ...

, in which the thermal gradient is large. The ending "stad" is from the Greek word στάδην meaning "in an upright position", from the root ἵστημι meaning to stand. The suffix "-stad" is now widely used in oceanography.

References

Oceanography {{ocean-stub