Geoscience Reference
In-Depth Information
Figure 2.17.
Average number of weeks of snow cover over the Northern Hemisphere,
based on the NSIDC blended weekly product (courtesy of M.J. Brodzik, NSIDC,
Boulder, CO).
strongly on the vertical density profile of the Arctic Ocean that in turn influences
sea ice formation.
Figure 2.17
shows the generalized distribution of snow cover duration over the
northern continents. The impact of latitude is obvious. In northern Canada, Alaska,
and Asia, snow is typically present 30-40 weeks per year. Terrestrial snow cover
classes have been developed according to climatic and vegetational zones, as well
as on the basis of depth, duration, and density (e.g., Bilello,
1957
; Benson,
1969
).
M. Sturm, J. Holmgren, and G. Liston, (
1995
) developed a classification for land
that takes account of the stratigraphic and textural attributes of a snow pack. The
classification has a number of categories of seasonal snow cover: tundra, taiga, mar-
itime, alpine, prairie, and ephemeral. There is also a special class for highly variable
mountain snow cover. Although several of the names follow earlier schemes based
on climatic/vegetation zones, these designations do not require such geographical
associations; only the relevant physical characteristics are considered (see Table 2.1
in Sturm et al.,
1995
). The classes were identified on the basis of a statistical analysis
