CryoSat-2's radar altimeter allows to observe the panArctic sea ice thickness up to 88°N on a monthly basis. However, calibration and validation are crucial to assess limitations and accuracy of the altimeter, and to better quantify the uncertainties involved in converting sea ice freeboard to thickness. We conducted four ship-based campaigns 2010-2012 to the pack ice north of Svalbard. Detailed in situ measurements of snow and ice thickness, freeboard, and snow stratigraphy and density were performed. The data were integrated with satellite data, airborne ice thickness observations, and aerial photography. Measurements from a Twin-Otter aircraft carrying a laser scanner and the CryoSat airborne simulator ASIRAS were obtained over one sea ice station. Here we discuss effects of snow properties on the penetration of the radar signal into the snow pack, along with in-situ, helicopter, and aircraft measurements for satellite calibration and validation purposes, based on results from two cruises in 2011.