Geoscience Reference
In-Depth Information
Figure 6.3.
Mean precipitation north of 60°N for the four mid-season months, based on
data from land stations and the Arctic Ocean with bias adjustments, the NCEP/NCAR
reanalysis and satellite retrievals (over open ocean). The fields are based primarily on
data for 1960-1989. Contours are at every 10 mm up to 80 mm and at every 50 mm
(dashed) for amounts of 100 mm and higher (by the authors).
land areas. The onset of the summer pattern features a strong transition between
May and June. Several processes are responsible for the terrestrial summer maxi-
mum. Cyclone activity over land areas is more frequent in summer than in winter
(see
Chapter 4
). Also, following melt of the snow cover, strong surface heating of
the land surface and plant photosynthesis promotes evapotranspiration. Convective
precipitation becomes fairly common, at least in the Low Arctic. Summer convec-
tive precipitation over land is not unknown even at quite high latitudes. The first
author observed convective precipitation during the summer of 1982 over the Hazen
Plateau of northern Ellesmere Island (82°N). His fascination turned to dismay when
it was discovered that the short aluminum tower on which the meteorological instru-
ments were mounted acted as a lightning rod!
A regional contributor to the summer precipitation maximum over land areas and
the central Arctic Ocean is the summer Arctic frontal zone (Serreze et al.,
2001
).
