On the variability of the Antarctic Circumpolar Current

• Main Author: Peterson, Ray George
• Other Authors: Nowlin, Worth D., Kattawar, George W., Ichiye, Takashi, McGuirk, James P., Reid, Robert O.
• Format: Thesis
• Language: English
• Published: Texas A&M University. Libraries 1987
• Subjects: Major oceanography; 1987 Dissertation P4855; Ocean-atmosphere interaction; Ocean currents; Antarctic Ocean; Ocean circulation; Antarctic; Southern Ocean; The Antarctic; Drake Passage; Faraday; Antarc*; British Antarctic Survey
• Online Access: https://hdl.handle.net/1969.1/DISSERTATIONS-754235

Typescript (photocopy). A time series of net transport during 1979 of the Antarctic Circumpolar Current through the upper 2500 m of Drake Passage was obtained as part of the International Southern Ocean Studies by Whitworth (1983), and was presented in corrected form by Whitworth and Peterson (1985). Spectral analyses are performed on records comprising the corrected series to determine the major sources for transport variability, and measurements from bottom pressure gauges at each side of the passage are used to extend the year-long series of transport, are related to fields of wind stress, and are compared with sea level observations. The net transport series is dominated in the sub-seasonal time scales by the lunar fortnightly and monthly tides and by baroclinic activity in the northern passage, processes that are independent of wind. Although the long-period lunar tides were included in the geostrophic calculations, the actual transport responses are probably ageostrophic. For seasonal time scales, transport variability is mainly barotropic, thereby allowing the use of bottom pressure records for extending the series. An extended transport series, spanning three continuous years plus an additional year, shows that seasonal changes approaching 40x10⁶ m³ s⁻¹ can occur in time intervals shorter than two months, and that the seasonal signals are not phase-locked. Seasonal fluctuations of bottom pressure at each side of the passage are consistent with what might result from changes in Sverdrup mass transport across the perimeters of the current as induced by variations in strength of the southern hemisphere subtropical and subpolar atmospheric systems. Synthetic subsurface pressure (SSP) derived from tidal and atmospheric sea level pressure series from the British Antarctic Survey base Faraday compares well with bottom pressure from the southern Drake Passage, and indicates the presence of the 18.6-year lunar nodal tide. SSP from Puerto Williams, Chile does not compare well with bottom pressure from the ...