How to Measure Ice Thickness at ICEX

This is the 22nd blog post in a series about ICEX 2011 by Jeff Gossett, Arctic Submarine Laboratory’s ICEX 2011 Exercise Director written on March 26, 2011.

The submarines completed one of our scientific tests yesterday measuring ice thickness.  It has involved several different agencies all coming together for a common goal.

There are several different ways of measuring or estimating ice thickness, none of which is perfect,

–Historically, a lot of the scientific data on ice thickness has been derived from upward-looking sonars installed on our submarines.  However, these “topsounders” only measure ice draft – that part of the ice extending below sea level.

–Airplanes and, more recently, satellites can measure how far the ice extends above sea level (the freeboard).

–The scientists have developed instruments that, when dragged along the ice, can measure the actual thickness but are limited in the thicknesses they can handle.

–And there is the old fashion method – going out on the ice, drilling a hole, and measuring the ice with tape measurer.

The Polar Bear Team (L-R) Bruce Elder (CRREL), Rick Hagen (NRL), Jackie Richter-Menge (CRREL), Mike Vermillion (NRL)

For this experiment, we are using all of these methods to measure the same stretch of ice so that all of the methods can be compared.  The way we made sure that all of these were used at the same place was to send a team out on the ice to establish a line that both the aircraft and the submarines could follow and to take the on-ice measurements.  This 4-person team was led by Jackie-Richter Menge from the Army’s Cold Regions Research & Engineering Laboratory (CRREL) in Hannover, NH.  Other members were Bruce Elder (also from CRREL) and two researchers from the Naval Research Laboratory (NRL), Rick Hagen and Mike Vermillion.  During the ICEX planning phase, this group was given the nickname of “Polar Bear Team” because their distance from the camp would make them polar bear bait.  Those of you who read previous posts will understand that this was meant purely as a joke.

In addition to the on-ice measurements and the submarines running beneath the “Polar Bear Line” with their topsounders, we had aircraft from both NRL and NASA overfly the line earlier in the week.

This is the first time that this many different sensors were brought to bear on the same piece of ice and should improve the scientists’ understanding of the accuracy of each of the sensors.

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