Kanitz T., Seifert P., Ansmann A., Engelmann R., Althausen D., Casiccia C., Rohwer E.G.
Leibniz Institute for Tropospheric Research, Permoserstrasse 15, D-04318 Leipzig, Germany; Ozone and RUV Laboratory, University of Magallanes, Punta Arenas 6210427, Chile; Physics Department, University of Stellenbosch, Stellenbosch 7602, South Africa
Kanitz, T., Leibniz Institute for Tropospheric Research, Permoserstrasse 15, D-04318 Leipzig, Germany; Seifert, P., Leibniz Institute for Tropospheric Research, Permoserstrasse 15, D-04318 Leipzig, Germany; Ansmann, A., Leibniz Institute for Tropospheric Research, Permoserstrasse 15, D-04318 Leipzig, Germany; Engelmann, R., Leibniz Institute for Tropospheric Research, Permoserstrasse 15, D-04318 Leipzig, Germany; Althausen, D., Leibniz Institute for Tropospheric Research, Permoserstrasse 15, D-04318 Leipzig, Germany; Casiccia, C., Ozone and RUV Laboratory, University of Magallanes, Punta Arenas 6210427, Chile; Rohwer, E.G., Physics Department, University of Stellenbosch, Stellenbosch 7602, South Africa
Three cloud data sets, each covering four months of observations, were recently recorded with a lidar at Punta Arenas (°53S), Chile, at Stellenbosch (34S, near Cape Town), South Africa, and aboard the research vessel Polarstern during three north-south cruises. By comparing these observations with an 11-year cloud data set measured with a lidar at Leipzig (°51N), Germany, the occurrence of heterogeneous ice formation (as a function of cloud top temperature) for very different aerosol conditions in the northern and southern hemisphere is investigated. Large differences in the heterogeneous freezing behavior in the mostly layered clouds are found. For example, <20%, 30%-40% and around 70% of the cloud layers with cloud top temperatures from-15°C to-20°C, showed ice formation over Punta Arenas, Stellenbosch, and Leipzig, respectively. The observed strong contrast reflects the differences in the free tropospheric aerosol conditions at northern midlatitudes, that are controlled by anthropogenic pollution, mineral dust, forest fire smoke, terrestrial biological material and high southern midlatitudes with clean marine conditions. Copyright 2011 by the American Geophysical Union.
Air pollution; Atmospheric aerosols; Biological materials; Deforestation; Dust; Marine pollution; Optical radar; Ships; Anthropogenic pollution; Cape Town; Cloud data; Cloud layers; Cloud-top temperatures; Forest fires; Germany; Heterogeneous freezing; Ice formations; Leipzig; Midlatitudes; Mineral dust; Research vessels; South Africa; Southern Hemisphere; Strong contrast; Tropospheric aerosols; Ice; aerosol; anthropogenic source; atmospheric pollution; data set; dust; forest fire; freezing; heterogeneity; lidar; marine environment; midlatitude environment; Northern Hemisphere; research vessel; smoke; Southern Hemisphere; troposphere; Aerosols; Air Pollution; Deforestation; Dust; Forest Fires; Germany; Radar; Ships; South Africa; Chile; Germany; Leipzig; Magallanes; Punta Arenas; Saxony; South Africa; Stellenbosch; Western Cape