We present results from field and laboratory experiments carried out to better understand the physical properties of first-year sea ice including its interaction with the atmosphere and the ocean. The predominant mechanism of sea-ice formation in the Arctic is changing from accumulation underneath multi-year sea ice to sea-ice formation starting in open water. However, our understanding of the growth and decay of Arctic sea ice relies mainly on measurements that were carried out in multi-year sea ice and so do the parameterizations of most numerical models. To improve our understanding of the formation, evolution and melting of first-year sea ice we carried out a winter-long field experiment and a number of laboratory experiments covering a full cycle of first-year sea-ice growth and decay. We focused particularly on measurements of the evolution of the salinity within sea ice using electrical impedance measurements.