King penguins breed on Crozet Island every Southern Summer. During the incubation period, each parent takes its turn to go and feed at sea. Their prey catching success is better when they reach the Northern boundary of the Antarctic Polar Front. But this boundary varies from year to year, in link with wide-scale phenomena like El Niño but also the Southern Annular Mode. 

Altimetry is one of the way of positionning these kind of fronts (not the only one, though). It also able to better understand the ocean circulation in general, but also the path of marine animals like the penguins.