Agulhas Current Variability and Loss of Waters into the SE Atlantic Ocean in the Retroflection Region

H. Thomas Rossby (University of Rhode Island), Johann Lutjeharms(University of Cape Town),
Olaf Boebel (University of Rhode Island)


The Agulhas Current Project is part of a cooperative research effort to study the mid-depth circulation around South Africa and in the southeastern Atlantic Ocean. It is one of three projects comprising the KAPEX (Cape of Good Hope Experiment). The field work is being done as a joint effort with scientists from the University of Cape Town (UCT), the Institut für Meereskunde (ifM-Kiel), WHOI and AOML/NOAA. The main objectives are: (1) to determine absolute transport of the Agulhas Current using "GPS-POGO", and (2) to identify pathways of motion along and out of the current by deploying isopycnal RAFOS floats in the current before it reaches the retroflection region directly south of southern Africa. In the Agulhas Retroflection, the Agulhas Current (a western boundary current flowing southwest near the southeast African coast) runs into the eastward flow of the Antarctic Circumpolar Current (ACC) and the northeastward flow of the Benguela Current. This causes the Agulhas to retroflect back to the east, with some waters lost through cross-frontal processes and through the shedding of rings into the southeast Atlantic. For the float program, three sound sources (R1, R2 and R3) were deployed in August, 1997 in the Agulhas Current region. Unfortunately, R3 failed soon after deployment for an as yet unknown reason. Other KAPEX sound sources are located farther west and will also be useful in tracking the floats (K7-K10: Kiel; M10-M12: WHOI). See Figure 1. A total of 46 floats have been deployed across the Agulhas Current, 16 in December 1997 and 30 in June 1998. For detailed information, go to the KAPEX web page.

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