THE MASS AND HEAT BUDGET OF THE ANTARCTIC ATMOSPHERE

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  • 1 U.S. Weather Bureau, Washington, D.C.
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Abstract

Mean meridional wind components and eddy transports of sensible heat across 72°S. latitude are computed for each of six atmospheric levels from 850 to 100 mb., using 1958 data from 10 Antarctic stations. Mean vertical motions are obtained from the meridional wind components; a heat balance is struck for each of the six atmospheric layers, with radiational heat changes obtained as a residual. Results are compared with observed long-wave radiational cooling rates for the dark period (1962), and with results of other investigators.

For the entire Antarctic atmosphere between 950 and 75 mb., results showed downward vertical motions and loss of heat by radiational processes throughout the year. The heat thus lost to space is on the order of 1022 cal. Downward motion is at a maximum (about 0.35 cm./sec.) in the middle troposphere; heat is transported into Antarctica by horizontal eddies and by the mean meridional cellular circulation, and the relatively small difference between this heat inflow and the heat lost through radiation produces the observed temperature changes. The heat added to the Antarctic atmosphere from sensible heat transport and realized potential heat is one order of magnitude greater than that from condensation processes. The spring warming of the Antarctic stratosphere appears to result directly from dynamical processes of warm air advection and vertical sinking rather than from a direct gain of heat through radiation absorption, at least in the lower stratospheric levels treated here.

Abstract

Mean meridional wind components and eddy transports of sensible heat across 72°S. latitude are computed for each of six atmospheric levels from 850 to 100 mb., using 1958 data from 10 Antarctic stations. Mean vertical motions are obtained from the meridional wind components; a heat balance is struck for each of the six atmospheric layers, with radiational heat changes obtained as a residual. Results are compared with observed long-wave radiational cooling rates for the dark period (1962), and with results of other investigators.

For the entire Antarctic atmosphere between 950 and 75 mb., results showed downward vertical motions and loss of heat by radiational processes throughout the year. The heat thus lost to space is on the order of 1022 cal. Downward motion is at a maximum (about 0.35 cm./sec.) in the middle troposphere; heat is transported into Antarctica by horizontal eddies and by the mean meridional cellular circulation, and the relatively small difference between this heat inflow and the heat lost through radiation produces the observed temperature changes. The heat added to the Antarctic atmosphere from sensible heat transport and realized potential heat is one order of magnitude greater than that from condensation processes. The spring warming of the Antarctic stratosphere appears to result directly from dynamical processes of warm air advection and vertical sinking rather than from a direct gain of heat through radiation absorption, at least in the lower stratospheric levels treated here.

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