Icebergs and Sea Ice Detected with Inverted Echo Sounders

M. Andres Physical Oceanography Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

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A. Silvano Physical Oceanography Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, and University of Turin, Turin, Italy

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F. Straneo Physical Oceanography Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

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D. R. Watts Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island

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Abstract

A 1-yr experiment using a pressure-sensor-equipped inverted echo sounder (PIES) was conducted in Sermilik Fjord in southeastern Greenland (66°N, 38°E) from August 2011 to September 2012. Based on these high-latitude data, the interpretation of PIESs’ acoustic travel-time records from regions that are periodically ice covered were refined. In addition, new methods using PIESs for detecting icebergs and sea ice and for estimating iceberg drafts and drift speeds were developed and tested. During winter months, the PIES in Sermilik Fjord logged about 300 iceberg detections and recorded a 2-week period in early March of land-fast ice cover over the instrument site, consistent with satellite synthetic aperture radar (SAR) imagery. The deepest icebergs in the fjord were found to have keel depths greater than approximately 350 m. Average and maximum iceberg speeds were approximately 0.2 and 0.5 m s−1, respectively. The maximum tidal range at the site was ±1.8 m and during neap tides the range was ±0.3 m, as shown by the PIES’s pressure record.

Corresponding author address: Magdalena Andres, Physical Oceanography Department, Woods Hole Oceanographic Institution, MS 21, 266 Woods Hole Road, Woods Hole, MA 02543. E-mail: mandres@whoi.edu

Abstract

A 1-yr experiment using a pressure-sensor-equipped inverted echo sounder (PIES) was conducted in Sermilik Fjord in southeastern Greenland (66°N, 38°E) from August 2011 to September 2012. Based on these high-latitude data, the interpretation of PIESs’ acoustic travel-time records from regions that are periodically ice covered were refined. In addition, new methods using PIESs for detecting icebergs and sea ice and for estimating iceberg drafts and drift speeds were developed and tested. During winter months, the PIES in Sermilik Fjord logged about 300 iceberg detections and recorded a 2-week period in early March of land-fast ice cover over the instrument site, consistent with satellite synthetic aperture radar (SAR) imagery. The deepest icebergs in the fjord were found to have keel depths greater than approximately 350 m. Average and maximum iceberg speeds were approximately 0.2 and 0.5 m s−1, respectively. The maximum tidal range at the site was ±1.8 m and during neap tides the range was ±0.3 m, as shown by the PIES’s pressure record.

Corresponding author address: Magdalena Andres, Physical Oceanography Department, Woods Hole Oceanographic Institution, MS 21, 266 Woods Hole Road, Woods Hole, MA 02543. E-mail: mandres@whoi.edu
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