Geoscience Reference
In-Depth Information
Figure 2.24.
Mean surface air temperature (°C) for January, April, July, and October
(adapted and updated from Rigor et al.,
2000
, by permission of AMS).
Over the Arctic Ocean, the formation of leads and polynyas locally permits
strong sensible and latent heat transfers into the atmospheric boundary layer. These
prevent winter SATs over the Arctic Ocean from reaching the extremes observed
in the interior of northeastern Siberia and northwest Canada. The importance of
the downward longwave radiation flux, and hence cloud cover, on winter SAT var-
iability over the central Arctic Ocean, is examined in
Chapter 5
. The highest winter
values are observed in the Greenland-Barents and Chukchi Sea sectors. This pattern
is largely established by the presence of open water that heats the overlying atmo-
sphere; open water is itself maintained by the warm North Atlantic Current.
During spring (as shown in the April field), the Siberian surface “cold pole”
has disappeared. The lowest temperatures are found over the Arctic Ocean and the
Canadian Arctic Archipelago. The April pattern clearly shows the effects of the cold
polar vortex (see
Chapter 4
), which extends throughout the troposphere and tends
