In March this year, Marc Cornelissen left Cape Arctichesky in northern Russia to lead the Pole Track 2005 expedition on a 1,000 km ski trek to the geographic North Pole. Along the way, the expedition team deployed mobile weather stations to transmit meteorological data, and collected a valuable set of snow depth measurements following a protocol that had been developed with ESA.

"While snow depth information holds the key to producing accurate maps of ice-thickness change over time with CryoSat, there are surprisingly few of these basic measurements readily available," says Malcolm Davidson, ESA CryoSat Validation Manager. "As a rule, people don't spontaneously spend weeks on end on the ice measuring this parameter. Marc Cornelissen's careful measurements of snow thickness during his expedition are thus very valuable indeed. The data will now be analysed by scientists participating in ESA's CryoSat calibration and validation programme."

In the long run, the data collected during the Pole Track expedition will contribute to the extensive validation program accompanying the CryoSat mission. The aim of this program is to collect independent measurements on the ground and from aircraft to fully understand and characterise the geophysical uncertainties in the CryoSat products. The data collected during the Pole Track expedition will be used, for instance, to estimate how much snow on top of sea ice affects the retrieval of sea-ice thickness information. Other large-scale campaigns have taken place in different locations across the Arctic over the last two years and have addressed different validation questions. Through the validation activities, CryoSat is expected to produ
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Contact: Malcolm Davidson
malcolm.davidson@esa.int
31-71-565-5957
European Space Agency
22-Sep-2005