Author(s): V. Verbeke; J. -L. Tison; H. J. Trodahl; T. G. Haskell

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Abstract: We report results from field investigation of banded features with differing optical scattering density occurring in columnar-congelation first-year landfast sea ice samples from the Eastern side of McMurdo Sound. To decipher the origin of these features, an analysis of the bands’spacing is combined with high-resolution measurements of the chlorinity (as a proxy to salinity), total gas content and gas composition (O, CO, N) in the white and dark portions of the bands at various levels in the core. It is shown that the banding corresponds to a 24 hours cycle throughout the core. It cannot therefore be attributed to surface temperature-driven growth rate fluctuations, since those are unlikely to show a daily cycle, or to sustain significant contrasts below0.5 m depth. Total gas content and chlorinity show sympathetic fluctuations between the dark and the white layers forming the banding, therefore precluding a biological origin for the banding cycle. Boundary layer fluctuations driven by tidal currents emerge as the best candidate to explain the observed features.

DOI:

Year: 2002