1. National Center for Atmospheric Research; Boulder Colorado USA
2. Now at School of Meteorology; University of Oklahoma; Norman Oklahoma USA
3. NASA Langley Research Center; Hampton Virginia USA
4. Chemical Sciences Division Earth System Research Laboratory; National Oceanic and Atmospheric Administration; Boulder Colorado USA
5. Cooperative Institute for Research in Environmental Sciences; University of Colorado Boulder; Boulder Colorado USA
6. Institute of Atmospheric Physics; German Aerospace Center; Oberpfaffenhofen Germany