1. Chemical Sciences Division, Environmental Science Research Laboratory; NOAA; Boulder Colorado USA
2. Physical Sciences Division, Environmental Science Research Laboratory; NOAA; Boulder Colorado USA
3. Global Systems Division, Environmental Science Research Laboratory; NOAA; Boulder Colorado USA
4. Meteorological Service of Canada; Downsview, Ontario Canada
5. Meteorological Service of Canada; Dorval, Quebec Canada
6. Center for Global and Regional Environmental Research; University of Iowa; Iowa City Iowa USA
7. Air Resources Laboratory; NOAA; Silver Spring Maryland USA
8. Science and Technology Corporation; Hampton Virginia USA