Spectral Simulations of Vegetation Indices in the Context of Landsat Data Continuity

Differences between the analogous spectral bands on Landsat-class sensors can have significant impacts on vegetation index comparisons. Vegetation indices based on satellite image data are widely used for change monitoring but, when derived from different satellite sensors, they will differ as a function of the uncorrectable differences between the analogous spectral bands used to generate the vegetation indices. This issue becomes important as available satellite sensors in the Landsat class are being considered in order to fill the anticipated gap in continuity of the Landsat TM and ETM+ data record. A follow-on mission is not expected any earlier than 2011. Among the current imagers examined in this study, which encompassed four vegetation targets and eight vegetation indices, either one of the IRS-P6 sensors or the SPOT-5 HRG is preferable to the CBERS- 2 HRCC as a replacement sensor from the standpoint of agreement with Landsat-based vegetation indices. Among the vegetation indices considered, the Global Environmental Monitoring Index (GEMI) proved to be the least sensitive to spectral dissimilarities between sensors and hence GEMI is worth considering for quantitative monitoring of environmental change using images from multiple sensors to fill the Landsat data archive.