Sub-Antarctic Flux and Dynamics Experiment (SAFDE)

Douglas S. Luther, Univ. of Hawaii at Manoa, Honolulu, Hawaii
Alan D. Chave, Woods Hole Oceanographic Institution, Woods Hole, Mass.
James G. Richman, Oregon State Univ., Corvallis, Oregon
Stephen R. Rintoul, CSIRO Marine Laboratories, Hobart, Australia
D. Randolph Watts, Univ. of Rhode Island, Kingston, Rhode Island
John A. Church, CSIRO Marine Laboratories, Hobart, Australia
Jean H. Filloux, Scripps Institution of Oceanography, La Jolla, California

Abstract:

Preliminary analyses will be presented of data from a large array of instruments deployed in March-April, 995, straddling the Sub-Antarctic Front portion of the ntarctic Circumpolar Current (ACC) southwest of asmania for two years. The intent of the experiment is to obtain long-duration, spatially coherent measurements of current and temperature in order to provide estimates of such quantities as the following (in ascending order of complexity): (i) barotropic transport structure and variability, (ii) baroclinic transport structure and variability, (iii) the relative importance of instabilities versus direct atmospheric forcing for production of barotropic and baroclinic variability at mesoscale frequencies, (iv) mean cross-ACC eddy heat and momentum fluxes and their divergences, and (v) momentum, energy and vorticity budgets as a function of cross-frontal position. The suite of instruments deployed incorporates both well-established ideas of oceanographic experimentation, as well as novel approaches. The former is represented by a nine-mooring, diamond-shaped local dynamics array, with maximum distance on a side of approximately 60 km, and where each sub-surface mooring supports 4-5 current meters and and up to 2 additional temperature sensors from 300 m to as deep as 3200 m. Straddling this LDA, and extending approximately 450 km along a NNE-SSW line, is an array of 17 horizontal electrometers (HEMs) and 18 inverted echo sounders (IESs). These seafloor instruments are well suited for observing currents like the ACC that are dominated by the largest vertical scales. The HEMs alone provide direct measurements of the horizontal transport (barotropic) components. The IESs and HEMs combined will provide, at least, both horizontal components of a two-vertical-mode description of the horizontal current field.