TY - JOUR T1 - Potential NDVI as a baseline for monitoring ecosystem functioning JF - International Journal of Remote Sensing Y1 - 2000 A1 - Stoms, D. M. A1 - Hargrove, W. W. KW - AVHRR KW - California KW - GAP KW - managed areas KW - NDVI KW - net primary production KW - NPP KW - Oregon KW - regression tree analysis KW - time integrated NDVI KW - Washington AB - 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. VL - 21 UR - ://000084681200014 ER - TY - ABST T1 - Acquisition and Evaluation of Data Sets for Comparative Assessment of Risk to Biodiversity on a Continental Scale: Threats to Biodiversity Y1 - 1998 A1 - Stoms, D. M. A1 - Kuhn, W. A. A1 - Davis, F. W. A1 - Final Report to the Environmental Protection Agency, C. A. pp KW - anthropogenic effects KW - biodiversity KW - NDVI KW - potential NDVI KW - rare species KW - species richness KW - stressors KW - West Cosat Transect PB - University of California, Santa Barbara N1 - [] ER - TY - JOUR T1 - Viewing geometry of AVHRR image composites derived using multiple criteria JF - Photogrammetric Engineering and Remote Sensing Y1 - 1997 A1 - Stoms, D. M. A1 - Bueno, M. J. A1 - Davis, F. W. KW - AVHRR KW - cloud removal KW - compositing KW - NDVI KW - Normalized Difference Vegetation Index KW - satellite zenith angle AB - 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. VL - 63 UR - ://A1997XC40700004 ER -