Marine Link
Saturday, December 15, 2018

GPS, Ice Profiling Sonar Used in Sea Level Variation Study

Maritime Activity Reports, Inc.

December 2, 2018

Image (L-R) The mooring being prepared on shore at the water's edge, the mooring being towed to the deployment site.

Image (L-R) The mooring being prepared on shore at the water's edge, the mooring being towed to the deployment site.

ASL Environmental Sciences said that Dr. David Holland of New York University, in collaboraon with Dr. Natalya Gomez at McGill University, is leading an invesgaon of sea level variaons in the Disko Bay region of western Greenland.

According to a statement from the company with over 40 years of experience in oceanographic, acoustic, remote sensing and ice research products and scientific consulting services, a shore-based system compares the direct arrival of GPS signals to the signals reflected off the sea surface to obtain sea level.

The presence of sea ice and icebergs complicate the measurements. A shore-mounted camera provides information about the surroundings and the presence of sea ice and icebergs when there is daylight.

Underwater sonar devices can supplement the camera-based observaons and eliminate the dependence on daylight to characterize the ice.

An ASL Ice Profiling Sonar (IPS) was chosen to make ice-dra measurements. Two sites located within 150 m of shore in water depths of 20–30 m were selected. One of the sites near Jakobshavn Glacier could not be accessed by a boat so it had to be accessed by a combinaon of helicopter and a small rubber boat.

ASL's engineering team was tasked with designing and building a lightweight mooring system which could be deployed by two people using the small rubber boat. In the summer of 2018, the field team successfully deployed both mooring systems.

The team is currently looking forward to the 2019 field season to service the shore-based and mooring-based instruments and recover the data stored on site.

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