1. Empa, Lab. for Air Pollution/Environmental Technology, Dübendorf, Switzerland.
2. Center for Climate Systems Modeling, ETH Zurich, Zurich, Switzerland.
3. Inst. of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, Switzerland.
4. Physics Inst., Climate and Environmental Division, and Oeschger Centre for Climate Change Research, Univ. of Bern, Bern, Switzerland.