The contribution of blowing snow and frost flower as sources of sea salt aerosols (SSA) over polar regions remains uncertain, despite its potentially important role in polar climate and chemistry. Using chemical transport models and satellite observations, we find that blowing snow emissions are the dominant source of SSA over sea ice during the cold season. We infer a monthly snow salinity on first-year sea ice that decreases from fall–spring, minimizing the model discrepancy to within 10 %.