Ice-forming nuclei in Antarctica: New and past measurements

- We measured the ice nuclei concentration at the Italian Mario Zucchelli Station (Antarctica).
- We compared our results with other IN measurements carried out in Antarctica continent.
- We made a review of recent and past IN Antarctica measurements.
- IN concentrations at the Italian station are lower than those reported previously.

The paper provides a review of past and a few new measurements of Ice-forming Nuclei (IN) in Antarctica. The few available published data were mostly obtained adopting different devices and methods and for a limited period of time. Consequently, data are scattered and give an incomplete picture of the Antarctic situation. It should be pointed out, however, that ice nucleation is an intricate process, depending on many parameters (supersaturation relative to ice and water, aerosol physical-chemical properties, possible conditioning and preactivation of particles, different modes of nucleation). Therefore, the uncertainty does not concern the Antarctic continent alone, but all measurements performed world-wide.A comparison of the published data can be made between Saxena and Weintraub (1988) at Palmer Station, and Ardon-Dryer et al. (2011) at the South Pole, as both studies measured IN in the immersion mode, even if at different temperature. Saxena and Weintraub (1988) obtained in three filters IN concentrations of about 104 m− 3 at T = − 6 °C, − 11 °C and − 13 °C, and 103 m− 3 at T = − 17 °C, in an additional filter (February-December 1983). At the South Pole Ardon-Dryer et al. (2011) obtained a concentration of about 5 × 102 m− 3 at T = − 19 °C, and the IN concentration increased until about 40 × 103 m− 3 at the activation temperature of − 26 °C.Such values are higher than those measured by Bigg (1973) near Antarctica, using a thermal diffusion chamber (deposition or deposition-condensation modes). IN concentrations measured at Terra Nova Bay are lower than those reported above, and are comparable to values reported for the Scott Base, Byrd Station and cruises at latitude 60°-70° S.