Abstract
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
C06018,
14 PP., 2006
doi:10.1029/2004JC002661
Weddell Sea iceberg drift: Five years of observations
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
The drift of 52 icebergs tagged with GPS buoys in the Weddell Sea since 1999 has been investigated with respect to prevalent drift tracks, sea ice/iceberg interaction, and freshwater fluxes. Buoys were deployed on small- to medium-sized icebergs (edge lengths ≤ 5 km) in the southwestern and eastern Weddell Sea. The basin-scale iceberg drift of this size class was established. In the western Weddell Sea, icebergs followed a northward course with little deviation and mean daily drift rates up to 9.5 ± 7.3 km d−1. To the west of 40°W the drift of iceberg and sea ice was coherent. In the highly consolidated perennial sea ice cover of 95% the sea ice exerted a steering influence on the icebergs and was thus responsible for the coherence of the drift tracks. The northward drift of buoys to the east of 40°W was interrupted by large deviations due to the passage of low-pressure systems. Mean daily drift rates in this area were 11.5 ± 7.2 km d−1. A lower threshold of 86% sea ice concentration for coherent sea ice/iceberg movement was determined by examining the sea ice concentration derived from Special Sensor Microwave Imager (SSM/I) and Advanced Microwave Scanning Radiometer for EOS (AMSR-E) satellite data. The length scale of coherent movement was estimated to be at least 200 km, about half the value found for the Arctic Ocean but twice as large as previously suggested. The freshwater fluxes estimated from three iceberg export scenarios deduced from the iceberg drift pattern were highly variable. Assuming a transit time in the Weddell Sea of 1 year, the iceberg meltwater input of 31 Gt which is about a third of the basal meltwater input from the Filchner Ronne Ice Shelf but spreads across the entire Weddell Sea. Iceberg meltwater export of 14.2 × 103 m3 s−1, if all icebergs are exported, is in the lower range of freshwater export by sea ice.
Received 12 August 2004; accepted 23 February 2006; published 14 June 2006.
Citation: (2006), Weddell Sea iceberg drift: Five years of observations, J. Geophys. Res., 111, C06018, doi:10.1029/2004JC002661.
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