Geoscience Reference
In-Depth Information
3
The Basic Atmospheric and Ocean
Energy Budgets
Overview
The fundamental role of the Arctic in the global climate system is to serve
as the Northern Hemisphere “heat sink.” On an annual basis, net receipts
of solar radiation in the Arctic are smaller than in equatorial regions.
The atmosphere and ocean work to balance this differential radiative
heating through poleward energy transports, with the atmosphere playing
the primary role. Because of stronger differential radiative heating in
winter, the atmospheric transports are largest at this time. The poleward
transports into the Arctic region itself are maximized around the prime
meridian and the date line. This reflects the location of the primary storm
tracks and, in winter, strong surface heat fluxes from open water areas.
An instructive approach to understand the energetics of the Arctic
heat sink is to consider the system from the perspective of its energy
budget. The energy budget of a given column of air, extending from the
surface to the top of the atmosphere, can be expressed in terms of four
components: (1) the change in atmospheric energy storage composed of
internal energy, potential energy, latent heat energy and kinetic energy, the
latter generally quite small; (2) the net radiation balance at the top of the
atmosphere; (3) the net poleward transport of atmospheric energy by the
atmospheric circulation; and (4) the net surface heat flux. The energy
of a given underlying column extending, from the surface downward, if
represented by ocean, is approximately represented by: (1) the change
in ocean energy storage in terms of latent heat as floating sea ice and
any overlying snow cover, and in the sensible heat of the ocean water;
(2) the horizontal convergence of the oceanic sensible heat flux and the
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