南京地区冬季大气冰核特征及其与气溶胶关系的研究

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

2011年11月15日～12月2日期间对南京地区近地面大气气溶胶和冰核进行了同步观测,综合分析了冰核浓度的特征及其与气溶胶粒子浓度的关系。结果表明:活化温度Ta为-20°C,水面过饱和度为1%时,南京地区冰核浓度NIN为0.352 L–1,与0.01～10μm气溶胶数浓度比值仅为4×10-8。冰核活化温度越低,湿度越大,冰核浓度越高。雾和降雨对冰核都有明显的清除作用。对比不同气团对南京地区冰核的影响发现,偏东方向的污染气团中冰核以及气溶胶的浓度最高,但是来自西北地区的气团中冰核占气溶胶的比例最高,这可能是由于冰相核化能力较强的沙尘气溶胶导致的。分析冰核与不同粒径段气溶胶的相关性发现,较大粒径气溶胶的表面积浓度与冰核相关性更高,本文也得到了由活化温度Ta和粒径大于0.5μm气溶胶数浓度N0.5～10μm共同计算冰核浓度的经验公式。

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 （NrN） observed during the campaign was 0.352 L i at the activation temperature （Ta） of --20℃, and the supersaturation with respect to water （Sw） equals 1%; the ratio of the IN toaerosol concentrations in the size range of 0.01--10 lain was 4x 10-8. The IN concentration would be high at low temperatures and high humidities. An obvious scavenging effect of fog and precipitation on 1N 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 Ta and the aerosol number concentration （N0.5-10 μm） was obtained.