Geoscience Reference
In-Depth Information
8
Climate Regimes of the Arctic
Overview
The Arctic is home to a wide variety of climate conditions. This spectrum
reflects, among other things, regional characteristics of the atmospheric
circulation, elevation, distance from moisture sources (continentality),
and properties of the surface. The present chapter both summarizes and
builds on what we have already learned through a focus on some of
these different climatic regimes. Up to now, relatively little attention has
been paid to the Greenland ice sheet. This region is hence given special
emphasis.
The Greenland ice sheet represents an extensive high elevation surface
for which the albedo remains high throughout the year. Although these
features distinguish its climate from other regions of the Arctic, ice sheet
climates are nevertheless quite varied. The interior is very cold and dry,
with summer temperatures well below freezing. Annual precipitation
over the central part of the ice sheet, isolated from moisture sources, is
around 100-200 mm. By comparison, the southeast coast is relatively
warm and very moist. This region is strongly influenced by the North
Atlantic cyclone track. Locally, in favored areas of orographic uplift,
precipitation may exceed 2,000 mm. Some particularly interesting aspects
of the ice sheet are its pronounced katabatic wind regime, related to
radiational cooling, the significant role of sublimation on the moisture
budget, and Greenland tip jets, which arise from interactions between
coastal topography and the synoptic-scale wind slow. In 2012, almost all
of the ice sheet briefly experienced summer melt, and summer melt extent
has shown a general increase over the past several decades. The annual
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