Fig. 3.

Ice nucleation active surface site densities (${\mathrm{n}}_s$) for BC as a function of temperature. Markers indicate values from this work, while lines are limit-of-detection parameterizations from both this work and previous works (8–10, 13, 14, 19). The method of surface-area normalization (BET or geometric [Geo.]) is indicated in the key. Error bars correspond to a range of BC contributions to ice nucleating particle concentrations (1 to 10%).