The study examined a 28 - year time series (1982 - 2009), which was composed of measurements taken by weather satellites
passing over the polar region.
The satellites
pass over the polar region several times each day to gather data; researchers can then form the data into images for analysis and publication.
Not exact matches
However, gravity data collected during the spacecraft's several close
passes over the south
polar region lent support to the possibility the sea might be global.