1. Norwegian Polar Institute Tromsø Norway
2. Department of Geosciences University of Oslo Oslo Norway
3. Now at Department of Earth Sciences University of Gothenburg Göteborg Sweden
4. Department of Earth Sciences Uppsala University Uppsala Sweden
5. C.N.R.‐Istituto sull'Inquinamento Atmosferico Roma Italy
6. School of Environmental Sciences University of East Anglia Norwich UK
7. Department of Geography, University of Sheffield Sheffield UK
8. LPC2E, UMR 7328, CNRS‐Université d'Orléans Orléans France