Antarctic Polar Front Zone
- Joseph L. Reid
Published Online: 21 MAR 2013
Copyright © 1971 by the American Geophysical Union.
Antarctic Oceanology I
How to Cite
Gordon, A. L. (1971) Antarctic Polar Front Zone, in Antarctic Oceanology I (ed J. L. Reid), American Geophysical Union, Washington, D. C.. doi: 10.1029/AR015p0205
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1971
Print ISBN: 9780875901152
Online ISBN: 9781118664438
- Antarctic polar front zone;
- Bathythermograph (BT);
- 176°E and 174°E;
- Expendable bathythermograph (XBT);
- 155°W, 170°W and 178°E;
- 120°W, 115°W and 128°W
The thermal structure across the antarctic polar front zone in the South Pacific is inspected. The structure is variable; however, it is often possible to identify some unifying pattern. A generalized thermal section can be constructed that contains all or most of the structural elements found by the particular bathythermograph sections. The basic components are as follows: The primary polar front zone is characterized by a cold water cell vertically elongated relative to other ocean features, which is isolated from the main mass of cold water further south. To the immediate south of the primary front is a warm water zone. The southern component of the polar front zone is the secondary polar front zone. Here the subsurface temperature minimum (T min) that identifies the Antarctic Surface Water has a very variable structure. Occasional indications of vertical convection are found. South of the double polar front zone, the Antarctic Surface Water is found to lie uniformly over the upper Circumpolar Deep Water with little sign of instability.
The mechanism responsible for the formation of the double polar front zone is not known. Various possibilities are offered. The common occurrence of the double front suggests that the mean wind may be the cause. However, the mean wind field that could produce the double front is not consistent with the wind distribution thought to exist over antarctic waters. The wind variations may be more important, and the passing of an isolated storm system may produce the double front. Another possibility is the influence of bottom topography on the transport of the Antarctic Circumpolar Current. An additional possibility is the progression of internal waves from south to north between the Antarctic Surface Water and upper Circumpolar Deep Water. The pycnocline gradually weakens between these two water masses from the Antarctic Divergence to the polar front zone. This weakening distorts the internal waves near the northern limit of the T min layer, causing a severance into two parts.
To study the antarctic double polar front zone properly, it would be necessary to conduct a multiship operation similar to those devoted to the Gulf Stream.