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Effect of critical latitude and seasonal stratification on tidal current profiles along Ronne Ice Front, Antarctica

Makinson, Keith; Schroder, Michael; Osterhus, Svein. 2006 Effect of critical latitude and seasonal stratification on tidal current profiles along Ronne Ice Front, Antarctica. Journal of Geophysical Research, 111 (C3), C03022. 15, pp. 10.1029/2005JC003062

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Abstract/Summary

The ice front region of Ronne Ice Shelf lies near the critical latitude of the semidiurnal M2 tide, the principal tidal constituent in the southern Weddell Sea. Here the Coriolis frequency almost equals the M2 tidal frequency, resulting in a strong dependence of the M2 tidal currents on depth and stratification and a boundary layer that can occupy the entire water column. Using data from four long-term moorings along Ronne Ice Front, we confirm the presence of strongly depth-dependent semidiurnal tidal currents and their sensitivity to changes in stratification. The time series show dramatic seasonal changes in tidal current profiles and significant interannual variability. During periods of stratification, the amplitude of the semidiurnal tides in the mid–water column shows a twofold increase and, despite being several kilometers offshore from the ice front, the tidal currents clearly show a second boundary layer originating from the adjacent ice shelf base. Together, these two boundary layers occupy most of the water column, up to 600 m deep, until intense sea ice formation and the production of High-Salinity Shelf Water erodes the vertical stratification. During winter when homogeneous conditions prevail, a single bottom boundary layer occupies the entire water column at some locations. This strong seasonality and sensitivity of the M2 tidal current to stratification highlights the difficulties of interpreting current data from short-term moorings while demonstrating that it is the best indicator for characterizing changes in stratification after direct observations of density variations.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1029/2005JC003062
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Global Interactions of the Antarctic Ice Sheet
ISSN: 0148-0227
Format Availability: Electronic, Print
Additional Information. Not used in RCUK Gateway to Research.: Full text not available from this server
Additional Keywords: Tidal currents ; Ronne Ice Shelf
NORA Subject Terms: Marine Sciences
Glaciology
Date made live: 30 Jul 2007 10:48
URI: http://nora.nerc.ac.uk/id/eprint/79

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