Arctic sea ice coverage
This film shows the Arctic sea ice coverage from June 2002 to October 2011. During this period the NASA satellite “Aqua” surveyed the natural microwave radiation of the earth’s surface on a daily basis. The degree of sea ice coverage can be derived from these data, independent of daylight and cloud cover. The distinguishing feature of these sea ice data is their high spatial resolution of around six kilometres, which permits observation of interesting phenomena:
Zoom 1. The formation of an ice tongue in the Greenland Sea area, north of Iceland. The occurrence of ice tongues is an important factor driving deep circulation of the oceans. Since the year 2004 the ice tongue has only occurred in a weak form, when at all.
Zoom 2. The wind-driven opening of polynias on the margin of the solid ice on the Siberian shelf. Polynias are considered to be salt factories in the Arctic, since the high rate of ice formation causes a relative increase in ocean salinity. Mixing processes in the polynia regions on the arctic shelf are important for the stability of oceanic stratification, which isolates the sea ice from the warmer Atlantic water.
Zoom 3. In September of 2011 the sea ice retreated to the second lowest coverage since the beginning of the satellite surveillance. The Northwest Passage through Canada’s island archipelago as well as the Northeast Passage north of Russia were to a large extent ice-free and could be traversed without the help of icebreakers.