| The flow through the Mozambique Channel is thought to be one of the two routes via which the South Equatorial Current feeds the Agulhas Currentin the Indian Ocean. This southward flux at the western part of the Indian Ocean balances more or less the inflow from the Pacific Ocean via theIndonesian throughflow in the eastern tropical part. Until very recently there was much uncertainty on the structure, magnitude and temporal variability of the flow in the Mozambique Channel because of a lack of direct observations. In the period 2000-2002 observations were obtained in this area from hydrographic cruises and from an array of current meter moorings that was deployed across the narrowest section. These observations are used to present and discuss the general characteristics of the current field. Results from the array of current meter moorings show that the currents can be characterised by two different regimes: one with strong and coherent currents, the other one with weak currents. During the strong current regime an anti-cyclonic eddy is formed which subsequently moves southward.The formation of these eddies occurs rather regular, with 4 eddies formed in the first year of observations and 5 in the second period of 9 months. The hydrographic observations show that the currents to the south of the mooring section are dominated also by anti-cyclonic eddies. All observations, including surface drifters, show that there is not a continuous western boundary current against the African shelf.The mean volume transport through the channel is estimated to be 14 Sv southwards. The time variability of the volume transport is oscillatory with minimum and maximum values varying roughly between 20 Sv northward and 60 Sv southward at a frequency similar to the frequency of the formation of the anti-cyclonic eddies. No seasonal variability has been found. At intermediate and deep levels against the African continental slope (1500 m and 2500 m) a relatively strong and northward flowing Mozambique Undercurrent is observed. The mean northward speed is 4.6 cms-1 (1500 m) and 4.5 cms-1 (2500 m). Hydrographic observations show thatin the deepest part of the channel (2000-2500 m) North Atlantic Deep Water is present, flowing in a northerly direction across the sill. The northward volume transport of NADW is estimated to be 2 Sv. |
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