Impact of surface conditions on thin sea ice concentration estimate from passive microwave observations

► We measured microwave emission from snow-covered ice grown in an outdoor tank. ► We calculated ice concentration from the measurements using five algorithms: NT, NT2, BSA, ASI and ECICE. ► Concentration in the tank was always 100%. ► Algorithms were evaluated based on this truth information. ► Any deviation from the truth was related to the ice, snow and meteorological conditions.