Airborne EM sea-ice thickness profiling over brackish Baltic sea water

Helicopter-borne electromagnetic-inductive (EM) ice thickness measurements have been performed in February 2003 along the Finish Baltic Sea coast. Both, the Gulf of Finland and the Gulf of Bothnia were surveyed. Measurements have been performed with a small, two-frequency EM-Bird, a towed sensor suspended 20 m below the heli-copter and operated 15 m above the ice surface. Results show that sufficiently accurate measurements were obtained even with minimum water salinities of 3 ppt in the Bay of Bothnia. Level ice thickness was in good agreement with information from ice charts. However, results also show the high degree of deformation of Baltic Sea ice, resulting in considerably higher mean ice thicknesses.