Circulation in Drake Passage revisited using new current time series and satellite altimetry

Abstract

The Drake Passage circulation was examined using in situ velocity time series gathered at five mooring sites across the Yaghan Basin (from January 2006 to March 2009), and at four mooring sites across Ona Basin (from February 2006 to April 2008). The moorings were located under the Jason satellite ground-track #104, allowing precise comparisons with various altimetry products. The mooring data suggested the existence of a permanent strong deep cyclonic circulation in the northeastern part of the Yaghan Basin and in the Ona Basin. The mean velocity vectors were observed to rotate with depth. Rotations of the mean velocity vector with depth indicated consistent downwelling except at the mooring located at 59&#9702 S, in the center of the Ona Basin. Temporal scales of variability observed from the mooring data were analyzed and leading modes of ariability were discussed. The moorings were located under the Jason satellite ground-track #104, allowing precise comparisons with various altimetry products. The mooring data suggested the existence of a permanent strong deep cyclonic circulation in the northeastern part of the Yaghan Basin and in the Ona Basin. The mean velocity vectors were observed to rotate with depth. Rotations of the mean velocity vector with depth indicated consistent downwelling except at the mooring located at 59&#9702 S, in the center of the Ona Basin. Temporal scales of variability observed from the mooring data were analyzed and leading modes of variability were discussed.