Temperature and Concentration Affect Particle Size Upon Sublimation of Saline Ice: Implications for Sea Salt Aerosol Production in Polar Regions

Using an environmental scanning electron microscope, we quantified for the first time aerosol-sized salt particles formed during the sublimation of sea ice as a function of temperature and concentration. The sublimation temperature of the ice is a dominating physical factor to determine the size of the residua: Below -20 degrees C, micron-sized pieces of salt emerge, whereas above the temperature large chunks of salt are detected. Another such aspect influencing the distribution of sizes in salt particles is the concentration: Micron-sized particles are observed exclusively at salinities below 3.5 psu, while below 0.085 psu particles with a median smaller than 6 mu m arise from sea ices at any subzero temperature. Moreover, when a chunk of salt sublimes at less than -30 degrees C to be dried and warmed later, a large number of sub-micron crystals will appear. We relate our findings to the production of the polar atmospheric sea salt aerosols.