Theformationof sea icecauses the concentration of salt in surfacewaters to increase; less sea icewould mean a smaller increase in the concentration of salt.
They announced preliminary findings in March but now have good data confirming large amounts of the water-ice just beneath the surface south of 60 degrees latitude.
Satellites have long been used to track ice extent (area), but calculating the thickness of the marine floes requires the overflying spacecraft to gauge the difference between the top of the ice surface and the top of the water - a relatively simple calculation then gives the overall volume.