TRANSPORT OF BOTTOM WATER IN THE ROMANCHE FRACTURE-ZONE AND THE CHAINFRACTURE-ZONE

Two moored arrays deployed in the Romanche Fracture Zone and Chain Fra cture Zone in the equatorial Atlantic Ocean provide two-year-long time series of current and temperature in the Lower North Atlantic Deep Wa ter and the Antarctic Bottom Water. Total rime-averaged transport of A ntarctic Bottom Water (potential temperature theta < 1.9 degrees C) ac ross the Mid-Atlantic Ridge amounts to 1.22 X 10(6) m(3) s(-1) eastwar d with a standard deviation of +/-0.25 X 10(6) m(3) s(-1). A time-aver aged transport of 0.36(+/- 0.23) x 10(6) m(3) s(-1) eastward is found for the Lower North Atlantic Deep Water in the 1.9 degrees < theta < 2 .1 degrees C temperature range, but this may represent only a fraction of the total flow of this water mass across the ridge. Contributions of the Romanche Fracture Zone and Chain Fracture Zone to the Antarctic Bottom Water transport are similar, while the Chain Fracture Zone has the greater share of Lower North Atlantic Deep Water transport. Semia nnual and annual periods are detected in the transport time series and together explain 24% of the Antarctic Bottom Water transport variance in the Romanche Fracture Zone. In the Chain Fracture Zone, Antarctic Bottom Water transport variance is dominated by fluctuations in the pe riod band 10-20 days.