Ice Road

Ship ice roads and changing ice cover - Gulf of Bothnia, Baltic Sea This image shows the northern part of the Baltic Sea over time, This image was created by combining three Envisat Advanced Synthetic Aperture Radar (ASAR) acquisitions taken over the same area. The colours in the image result from variations in the surface. Radar backscatter from sea ice is dependent on the dielectric properties and spatial distribution of the ice. Such factors as ice age, surface roughness, internal geometry, temperature, and snow cover will also all play a role in the affect of radar backscatter, Water just starts to freeze in the December acquisition, the end of February shows an extended ice cover (redand blue) and some ship ice roads close to the coast, connecting Oulunsalo to 1-lailuoto Island and Tornio. Early May shows the ice cover has withdrawn significantly (yellowish edge). acquired on 14 December 2008, 22 February 2009 and 3 May 2009 by Envisat/AS4R, ©ESA