Effect of spatial resolution on thermal IR sensing of plant canopies

摘要

Satellite observations of agricultural and other plant canopies in the thermal IR regime have generally been at spatial scales of tens to hundreds of meters. Use of the thermal IR at higher resolutions is confounded by the mixture problem and otherassociated scaling issues. Advances in sensor technology will extend our capabilities for IR measurements to shorter wavelengths and yield improved spatial resolutions. However, experience with aircraft remote sensing observations has indicated that caremust be exercised in understanding the interaction effects of viewing geometry at these higher resolutions. The utilization and scaling of observables with multi-resolution remote sensing data sets remain a difficult problem. At high spatial resolutionthe three-dimensional character of scene components contained within a pixel must be considered. In this paper, we explore the variability in brightness temperature and the co-variation of NDVI with brightness temperature as a function of viewing geometry and changing spatial resolution. Using three-dimensional models for both canopy reflectance and thermal IR exitance, we employ a theoretical analysis for an agricultural scene where previous comparisons and measurements were available.