Feature covariates in determining the development of pine beetles. The species studied in both projects develop at landscape-level scales measured in tens, rather than hundreds, of meters. According to Crabtree, the available low-resolution 4-kilometer datasets available are not sufficient. However, the newly generated 30-meter resolution solar radiation and temperature information "is a fabulous dataset for these models." While solar radiation affects many biological processes that influence the distribution of species and their habitat selection, this data seldom appears explicitly as a covariate in habitat studies. In winter, the grass is covered by deep snowpack. Because it is too hard for animals to uncover food, the ungulate species, especially bison, may migrate from park to unprotected areas where they are killed by local farmers. This migration is mostly determined by forage production and snow melting. Jennifer Sheldon, YERC vice president and lead project scientist, is studying small mammals in Yellowstone. Dr. P. J. White, director of Yellowstone National Park, is responsible for the wildlife management policy in Yellowstone. Sheldon and White are now working with NASA to model the distribution of forage production and snow melting in Yellowstone using solar radiation and temperature datasets. Conclusion The high resolution solar radiation and temperature datasets are important and previously unavailable data inputs for modeling biological processes in Yellowstone National Park. About the Authors Shengli Huang, a postdoctoral research scientist with NASA Ames Research Center, is an ecologist who majored in geography and ecology. He has been using GIS and remote sensing tools to conduct research in Yellowstone for four years. Pinde Fu, a project lead and senior developer with Esri Applications Development Services, studied solar radiation modeling with his advisor, Dr. Paul Rich, during his doctoral studies. He and Rich developed the Esri solar radiation calculation engine. For More Information The Solar radiation tools are fully explained at the Esri Web site (http://webhelp.esri.com/ arcgisdesktop/9.2/index.cfm?TopicName= An_overview_of_the_Solar_Radiation_tools). For more specific algorithms and applications, see the following publications: PENN STATE | ONLINE Geospatial Education Portfolio Penn State offers high-quality online education programs to help you achieve your personal and professional goals. Master of Geographic Information Systems Postbaccalaureate Certi cate in Geographic Information Systems Postbaccalaureate Certi cate in Geospatial Intelligence Fu, Pinde. A Geometric Solar Radiation Model with Applications in Landscape Ecology. Ph.D. Thesis, Department of Geography, University of Kansas. Lawrence, Kansas, 2000. Fu, Pinde, and Paul M. Rich. "A Geometric Solar Radiation Model with Applications in Agriculture and Forestry," Computers and Electronics in Agriculture 37: 25­35. 2002. Rich, Paul M., Ralph Dubayah, William A. Hetrick, and Shawn C. Saving. "Using Viewshed Models to Calculate Intercepted Solar Radiation: Applications in Ecology," American Society for Photogrammetry and Remote Sensing Technical Papers, 524­529. 1994. Huang, Shengli, Paul M. Rich, Robert Crabtree, Christopher Potter, and Pinde Fu. "Modeling Near-Surface Air Temperature from Solar Radiation and Lapse Rate: Application over Complex Terrain in Yellowstone National Park, USA," Physical Geography, 29, no. 2: 158­ 178. 2008. ArcUser Spring 2009 31 www.worldcampus.psu.edu/arcuser Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce. U.Ed.OUT 09-0677/09-WC-147edc/bjm www.esri.com