Surges of Antarctic Bottom Water into the North Atlantic

John A. Whitehead Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole Massachusetts

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Abstract

Current meter records show that Antarctic Bottom Water surges into the western North Atlantic with roughly a sixty-day period. A time-dependent mass budget which incorporates estimated volume fluxes from geostrophic calculations, surges with a sixty-day period, a known time-average volume of the very coldest water in the North Atlantic, and a constant mixing coefficient predicts vertical excursions of 160–230 meters for the 1.1° isotherm and 45–60 meters for the 1.2° isotherm. Available data do not reveal such an excursion. The reason for the lack of the excursions, is that earlier estimates of volume of the very coldest water were too small. Corrected tables are presented. The disagreement between the current meter results and the geostrophic circulations remains.

Abstract

Current meter records show that Antarctic Bottom Water surges into the western North Atlantic with roughly a sixty-day period. A time-dependent mass budget which incorporates estimated volume fluxes from geostrophic calculations, surges with a sixty-day period, a known time-average volume of the very coldest water in the North Atlantic, and a constant mixing coefficient predicts vertical excursions of 160–230 meters for the 1.1° isotherm and 45–60 meters for the 1.2° isotherm. Available data do not reveal such an excursion. The reason for the lack of the excursions, is that earlier estimates of volume of the very coldest water were too small. Corrected tables are presented. The disagreement between the current meter results and the geostrophic circulations remains.

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