1. Department of Applied Physics, University of Eastern Finland, Kuopio 70211, Finland
2. Finnish Meteorological Institute, Kuopio Unit, Kuopio
70211, Finland
3. National Centre for Atmospheric Research, Boulder, Colorado 80305, United
States
4. Aerodyne Research, Inc., Billerica, Massachusetts 08121-3976, United States
5. Department of Physics, University of Helsinki, Helsinki 00014, Finland
6. Finnish Meteorological Institute, Climate Change,
Helsinki 00101, Finland