In situ

Definition of in situ: In it's original place. From the Latin word situs meaning place. This is the common definition for in situ, other definitions can be discussed in the article

In oceanography this term is mostly used with instruments that measure properties directly in the sea: In situ measurement, in situ sensor, in situ instrument.

Also used to describe the temperature that a water volume has at the depth it is located: In situ temperature.