1. Leibniz Institute for Tropospheric Research, Leipzig, Germany
2. German Environment Agency, Berlin, Germany
3. Laboratory for Atmospheric Physics, Institute for Physics Research, Universidad Mayor de San Andres, La Paz, Bolivia
4. Department of Chemical, Medical and Environmental Sciences, National Physical Laboratory, Teddington, Middlesex, United Kingdom
5. Materials and Air Pollutants, Federal Institute for Materials Research and Testing, Berlin, Germany
6. Aerosol and Particle Diagnostic, Physikalisch-Technische Bundesanstalt, Braunschweig, Germany