Asian dust impacts on heterogeneous ice formation at Wuhan based on polarization lidar measurements

Abstract

We analyzed 456 thin mid-level cloud layers based on two-year polarization lidar measurements in Wuhan (30.53°N, 114.37°E), China. Dust separation algorithm based on lidar measurements was implemented to identify clouds under influences of dust and non-dust components. Through comparisons of ice-containing cloud fractions under dust and dust-free conditions, significant impacts of Asian dust on heterogeneous ice formation are found. 20% more ice-containing cloud fractions occurred under influence of Asian dust at temperature range from −25 to −10 °C. More than 90% of dust-related heterogeneous ice formation were associated with polluted dust. In order to investigate the efficiency of non-dust components to serve as ice nuclei (IN), results at two continental sites (Wuhan, East Asia and Leipzig, Central Europe) with very different aerosol loadings were compared and discussed. Weak and similar ice nucleation characteristics under dust-free conditions of different loadings of sulfate, black carbon and organic carbon, may suggest such components are all less effective INs.