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.

A related topic are Inline measurements: Sensors or instruments are situated in a flow-through system, e.g., on board a ship, in which water is pumped from the outside. This technique is applied in the FerryBox. The advantages of Inline measurements are:

• The sensors are well protected and therefore have a longer lifetime
• The calibration of the sensors is more stable and the calibration procedure is easier
• Biofouling can easily prevented by applying chemical methods (cleaning).