Characteristics of Atmospheric Ice Nuclei and Its Relationship to Aerosols in Winter in Nanjing

Simultaneous surface measurements of ice nuclei (IN) and aerosols in Nanjing from November 15 to December 2, 2011, are presented to investigate the characteristics of the IN concentration and the relationship between IN and aerosols. The results show that the mean concentration of IN (N_IN) observed during the campaign was 0.352 L^-1 at the activation temperature (T_a) of -20℃, and the supersaturation with respect to water (S_w) equals 1%;the ratio of the IN to aerosol concentrations in the size range of 0.01-10 μm was 4×10^-8. The IN concentration would be high at low temperatures and high humidities. An obvious scavenging effect of fog and precipitation on IN was observed. A comparison of IN in different air masses showed that the concentration of IN and aerosols in an air mass that originated from a polluted area to the east was the highest, but the ratio of IN to aerosols was the highest when the air mass originated to the northwest, which might be because of the high ice-nucleating ability of dust particles. The correlation coefficient between IN and aerosols in different size ranges showed that IN with larger particle surface concentrations was much more highly correlated with aerosols. The ice nuclei empirical equation considering T_a and the aerosol number concentration (N_{0.5～10 μm}) was obtained.