%0 Journal Article %J International Journal of Remote Sensing %D 2000 %T Potential NDVI as a baseline for monitoring ecosystem functioning %A Stoms, D. M. %A Hargrove, W. W. %K AVHRR %K California %K GAP %K managed areas %K NDVI %K net primary production %K NPP %K Oregon %K regression tree analysis %K time integrated NDVI %K Washington %X Baseline data are needed to determine the overall magnitude and direction of change in ecosystem functioning. This letter presents an approach to estimate potential NDVI from environmental variables and training data of actual NDVI in nature reserves. Patterns of deviations of actual NDVI from the baseline generally correspond with land-use types in the western United States. %B International Journal of Remote Sensing %V 21 %P 401-407 %8 2000 %G eng %U ://000084681200014 %0 Generic %D 1998 %T Acquisition and Evaluation of Data Sets for Comparative Assessment of Risk to Biodiversity on a Continental Scale: Threats to Biodiversity %A Stoms, D. M. %A Kuhn, W. A. %A Davis, F. W. %A Final Report to the Environmental Protection Agency, C. A. pp %K anthropogenic effects %K biodiversity %K NDVI %K potential NDVI %K rare species %K species richness %K stressors %K West Cosat Transect %I University of California, Santa Barbara %8 September 30, 19 %G eng %0 Journal Article %J Photogrammetric Engineering and Remote Sensing %D 1997 %T Viewing geometry of AVHRR image composites derived using multiple criteria %A Stoms, D. M. %A Bueno, M. J. %A Davis, F. W. %K AVHRR %K cloud removal %K compositing %K NDVI %K Normalized Difference Vegetation Index %K satellite zenith angle %X The U. S. Geological Survey currently generates composites of AVHRR imagery based on a single objective--maximizing the Normalized Difference Vegetation Index--as a means of reducing cloud contamination. Our research supports the findings of others that in some cases, NDVI is maximized at the expense of optimal viewing geometry; that is, satellite zenith angles are often further off-nadir than necessary to ensure cloud-free viewing. We explore various compositing methods by systematically varying weights on NDVI, satellite zenith angle, and maximum apparent temperature. A test composite of California from September 1990 appears to be superior to the maximum NDVI and maximum apparent temperature composites in several respects. First, the satellite zenith angle distribution is more closely clustered about nadir, which minimizes atmospheric path length, spatial distortion, and bidirectional reflectance effects. Second, neighboring pixels are more frequently selected with similar viewing geometry and atmospheric conditions. %B Photogrammetric Engineering and Remote Sensing %V 63 %P 681-689 %8 1997 %G eng %U ://A1997XC40700004