Changes in the sea ice volume is currently measured by satellite, airborne and ground observations. Satellite data provides information on extent, while airborne and ground observations are used for validation. Only few direct measurements of seasonal sea ice thickness measurements exist. At five sites in Northeast Greenland ice thickness were obtained during 1950-60’ies from the former weather stations operating before the satellite system was launched in late 1970’ies.
With the establishment of the marine part of the GEM monitoring in 2002, seasonal snow and sea ice thickness was initiated in Young Sund in collaboration with the Sirius Dog Sled Patrol. In GIOS we will extend similar measurements to the localities of our mobile measuring units to cover a larger part of Greenland. In addition, GIOS will install snow radar on a twin-otter instrument package deployed for ice sheet mapping as part of an international cryosphere monitoring program.
Airborne surveying around Greenland has been obtained routinely since 1998, as part of an international cryosphere monitoring program. The largest errors for ice volume estimates are due to the lack of knowledge of snow depth, and there is a demand for adding a snow radar to the airborne instrument package. Continuous flights in the Fram Strait over the existing array of moored upward looking sonars, will serve to improve sea ice thickness measurements, in an area with the largest Arctic sea ice outflow. All the mentioned programs have strong both national and international participation.