The aim of CALVA is to gather series of in situ observations in Adélie Land and at the Dome C, which are needed to better evaluate and improve Antarctic meteorological models and global climate models over Antarctica. The observations also aim to contribute to improve remote sensing methods. In Adelie Land, CALVA focuses on precipitation, extreme dynamic atmospheric boundary layer (catabatic winds), drifting, and blowing snow. At Dome C, CALVA also focuses on precipitation and clouds, and on the boundary layer, which is extreme here in terms of temperature and inversions and exchange fluxes with the snow surface. These are poorly known aspects of the Antarctic meteorology and climate, which are consequently poorly represented or simply ignored (blowing snow) in the models used for IPCC climate change predictions. The observations thus aim to improve those predictions, in particular those of the surface mass balance of the ice sheet and impact on sea-level.