Volume transport of the Malvinas Current: Can the flow be monitored by TOPEX/POSEIDON?

Abstract

Current meter measurements were collected between 40° and 41° S in the Malvinas (Falkland) Current from December 1993 to June 1995. Owing to the premature failure of a mooring, a reliable volume transport time series could only be calculated for 254 days, leading to a mean transport of about 41.5 Sv with a standard deviation of 12.2 Sv. This time series is tentatively extended to 386 days. It is also shown that the TOPEX/POSEIDON altimeter, combined with the statistical information on the vertical structure of the current provided by the current meters, can be used to sensitively monitor the flow. A 3-year-long time series of transport is derived, which is well correlated (0.8) to the transport estimated from current meters, including about 60% of the variance of the flow at periods beyond 20 days; this series makes it possible to consider a relatively broad spectral range. Dominant periods are 50-80 days and close to 180 days. Interannual variations are large. Comparatively, little energy is found at the annual period, suggesting that the Malvinas Current has only little impact on the annual migrations of the confluence. The predominance of a semiannual cycle is compatible with a remote forcing of the flow suggested by previous numerical studies. Copyright 1999 by the American Geophysical Union.