Research ArticleGEOLOGY

Wind causes Totten Ice Shelf melt and acceleration

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Science Advances  01 Nov 2017:
Vol. 3, no. 11, e1701681
DOI: 10.1126/sciadv.1701681
  • Fig. 1 Ice flow regime of TIS, 2001 to 2014.

    (A) Mean surface velocity from 2001 to 2014. A green polygon outlines the region of velocity measurements used in this analysis. A white box outlines the region used in a previous study by Roberts et al. (6). Inset map shows the location of TIS. (B) Linear trend of surface velocity indicates an overall slowdown of TIS from 2001 to 2014, whereas the surrounding grounded ice accelerated. Accelerations close to the ice front reflect calving processes. (C) The curl of the mean surface velocity is used to identify shear margins within TIS. The orange polygon outlines the region of surface velocities plotted in fig. S2B.

  • Fig. 2 Upwelling and ice-shelf velocity time series.

    (A) Vertical water velocity at the bottom of the Ekman layer estimated from surface-water divergence caused by wind stress; plotted is the mean velocity within the gold polygon in Fig. 3D. Light and dark lines are low-pass–filtered to 12 and 24 months, respectively. (B) Dark red line is the ice velocity derived from 629 displacement measurements shown as thin gray lines bounded by the shaded region of estimated uncertainties (fig. S5). Blue lines are from displacement observations published in a previous study by Roberts et al. (6). The horizontal axis of (B) has been shifted relative to (A) to account for an observed 19-month lag.

  • Fig. 3 Reanalysis fields and ice-shelf velocity.

    (A to D) Regression coefficients of linear least-squares fits of TIS velocity and zonal wind stress [μPa/(m a−1)] (A), meridional wind stress [μPa/(m a−1)] (B), sea-ice concentration [%/(m a−1)] (C), and upwelling [(μm s−1)/(m a−1)] (D). All panels contain gray vectors representing mean wind velocity, gray 1-km bathymetric contours, and a gold polygon outlining the region of upwelling referred to in Fig. 2A. Gray shading denotes statistical insignificance at the 95% confidence level. Coefficients of determination are given in fig. S4.

  • Fig. 4 Schematic of mCDW upwelling along the Antarctica’s Sabrina Coast.

    Around Antarctica, the warmest waters are found in the deep ocean north of the continental shelf break. Where wind stress (gray vectors) causes surface waters to part, warm deep water (red arrow) can upwell, surmount the continental shelf, and melt nearby ice shelves from below. Seafloor color depicts the covariance of TIS velocity and local upwelling as in Fig. 3D, indicating where wind-driven upwelling is closely linked to TIS velocity.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/11/e1701681/DC1

    fig. S1. Upwelling brings warm water onto the continental slope.

    fig. S2. Ice-shelf thinning drives acceleration.

    fig. S3. Regression of upwelling and TIS velocity.

    fig. S4. Coefficients of determination.

    fig. S5. Uncertainty estimates for TIS velocity time series.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Upwelling brings warm water onto the continental slope.
    • fig. S2. Ice-shelf thinning drives acceleration.
    • fig. S3. Regression of upwelling and TIS velocity.
    • fig. S4. Coefficients of determination.
    • fig. S5. Uncertainty estimates for TIS velocity time series.

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