干旱区生态环境知识资源中心

The NASA EO-1 Hyperion observations were utilized to derive at-sensor Top-of-atmosphere (TOA) and ATREM-corrected surface reflectance over three study sites of different land use types. Direct comparisons between TOA and ATREM reflectance showed the most disagreement in the visible spectral region and regions that were affected by water absorption features. Nevertheless, as little as 3% overall differences were found for an arid dessert scene. Furthermore, example applications using Hyperion at-sensor TOA reflectance were investigated. Selected band ratio vegetation indices calculated from both TOA and surface reflectance were correlated (r similar to 0.6 to 0.94) but differed in magnitude. For instance, NDVI calculated from at-sensor TOA reflectance consistently showed lower values. A potential quick-look product using these indices to model relative vegetation stress was demonstrated in this study.