Geoscience Reference
In-Depth Information
Figure 2.2.
Definition of Arctic seas, based on Russian sources (from Welsh et al.,
1986
).1. Greenland Sea, 2. Labrador Sea, 3. Baffin Bay, 4. Canadian Arctic Archipelago,
5. Beaufort Sea, 6. Bering Sea, 7. Chukchi Sea, 8. East Siberian Sea, 9. Laptev Sea, 10.
Kara Sea, 11. Barents Sea, 12. Greenland Arctic Basin, 13. North American Arctic Basin,
14. Russian Arctic Basin, 15. European Arctic Basin, 16. Kane Basin, 17. Norwegian
Sea (from Welsh et al,
1986
, by permission of United States Government).
circulation, the surface energy budget and the hydrologic budget. Accordingly, we
introduce some basic aspects of sea ice processes and Arctic oceanography here.
The Northern Hemisphere sea ice cover, the bulk of which lies within the Arctic
Ocean, ranges in extent from upwards of 15 million km
2
in March to less than half
that value in in September, the end of the melt season. Extent is generally defined as
regions with an ice concentration (i.e., a fractional ice cover) of at least 15 percent.
There is large variability in extent from year to year, largest in the summer months.
As introduced in
Chapter 1
, analysis of the satellite record (1979 to present) docu-
ments negative linear trends in extent for all months, strongest for September. Mean
ice extent for March and September, based on the 1979-2001 period, is shown in
Figure 2.4
. During winter, ice extent in the Arctic Ocean is largely constrained by
the surrounding landmasses and in the Greenland, Norwegian, and Barents seas
