Characteristics of immersion freezing nuclei at the South Pole station in Antarctica

The effectiveness of aerosols as immersion freezing nuclei at the South Pole station was investigated during January and February 2009 using the FRIDGE-TAU. The analysis consisted of testing the freezing temperature of about 100-130 drops per sample containing aerosols collected at ground level and on a balloon lifted to different heights. All the drops froze between -18 degrees C and -27 degrees C. The temperature in which 50% of the drops froze occurred at -24 degrees C, while nuclei concentration of 1 L(-1) at -23 degrees C was calculated. Meteorological conditions such as wind speed, ice precipitation as well as the trajectories of the air masses affected the ice nuclei concentrations. Higher concentrations were observed on days when the winds were stronger or when the air mass originated from the sea.