Spatial variability of freeboard, snow and sea ice thickness in the Svalbard CryoVEx 2011 CAL/VAL region

One of the uncertainties of the CryoSat-2 is a snow loading factor used in conversion of satellite derived freeboard to mean sea ice thickness. In order to examine variability of the ice and snow conditions within the scale of the CryoSat-2 footprint in-situ measurements were conducted during the R/V Lance expedition on Spring 2011. Snow thickness and surface elevation measurements were done in regular manner by using a snow stick and a rotating laser. Most of the measurements were done in 2.5 meters spacing along a line typically crossing the floe. Altogether, 4109 meters of measurements lines were surveyed during the expedition. The snow loading was surprisingly large and in many locations the ice freeboard was negative although the sea ice was 1-2 meters thick. The mean snow thickness of the all measurements was 36 cm and the mean freeboard was only 3 cm. There are a noticeable differences in snow thicknesses among the measurements sites, which is partly due to the different ages of the floes, but it's evident that the snow cover is much thicker in the deformed ice regions. Over the undeformed ice areas, the mean snow thickness was 23 cm, while in ridges it was 54 cm. Mean freeboard were 2.4 cm and -0.3 cm, respectively.