We apply a broad range of methods to realize our research projects and to make progress in the different research topics. These methods reach from field observations (in-situ on, above or under the ice) to satellite observations, including buoy and airborne measurements. We also run and develop various numerical models and connect them to observations (data assimilation). This is done to generalize our findings and to enable large-scale conclusions, which cannot be reached from observations alone, because those are limited in temporal and spatial coverage.