1. Department of Hydrology and Water Resources; University of Arizona; Tucson Arizona USA
2. Now at USDA Agricultural Research Service; Tucson Arizona USA
3. Institute of Arctic and Alpine Research and University of Colorado; Boulder Colorado USA
4. National Center for Atmospheric Research; Boulder Colorado USA
5. Department of Botany and Program in Ecology; University of Wyoming; Laramie Wyoming USA
6. Department of Atmospheric Science and Program in Ecology; University of Wyoming; Laramie Wyoming USA
7. School of Natural Resources and the Environment; University of Arizona; Tucson Arizona USA
8. Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA