Observations of short term variations in the chromatic activity suggest that the star undergoes differential rotation, with a rotation period of about 11-13 days.

Global parameters could then be improved and new ephemeris for the orbital motion as well as for another long term variation were derived.

This is mainly due to the large short term variations in produced power and the relatively small size of the WEC.

The salinity also shows long term variation, it was reported as being freshwater in 1929 and 1939, but saline in 1949.

There is also a longer term variation which is less well understood.

Its brightness varies between magnitude +2.75 and +3.02 over a 72 day period, along with a 2,000 day period of long term variation.

Short term variations are compensated by the air receiver on the compressor.

The term magnetic variation is a synonym, and is more often used in navigation.

In the theory of price indices, economists also use the term compensating variation, which is yet another unrelated concept.

Other senses of the term "double variation"