The European Space Agency’s (ESA) CryoSat satellite is now providing highly accurate data on the thickness and volume of Arctic Ocean ice
. Using a high-resolution
synthetic aperture radar that sends down pulses of microwave energy, the satellite can measure the difference between the top of the ice and water in the cracks, or leads, that separate the floes. By measuring the height of the ice above water, which usually represents only one-eighth of total ice thickness, the satellite can provide data on ice thickness to within 10 to 20 centimeters, or 4 to 8 inches. The CryoSat satellite was launched in 2010, and since then scientists have been validating the measurements against other data from plane-based instruments and direct, on-ice measurements. “We now have a very powerful tool to monitor the changes taking place at the poles,” said Volker Liebig, the ESA’s director of Earth Observation.