Validation Sites

Knowledge of the Land Surface Emissivity (LSE) in the Thermal Infrared (TIR: 8-12 um) part of the electromagnetic spectrum is essential to derive accurate Land Surface Temperatures (LSTs) from spaceborne TIR measurements. TIR data are supplied by instruments on several satellite platforms including ASTER, which was launched on the Terra satellite in 1999. ASTER has five bands in the TIR and a spatial resolution of 90 m. We are currently producing a global mean seasonal, gridded, Land Surface Temperature and Emissivity (LST&E) database using all the ASTER scenes acquired since launch (2000). The first region completed is over North America, termed the North American ASTER Land Surface Emissivity Database (NAALSED). NAALSED v2.0 has been validated using in-situ samples collected at ten pseudo-invariant sand dune sites covering a broad range of surface emissivities in the TIR. Results indicate that the mean emissivity difference between NAALSED and the validation sites is typically less than 0.02 (2 %). This document presents a detailed description of each dune site with accompanying figures showing an ASTER false-color image of each dune site (blue dots show sample sites) and emissivity spectra from NAALSED and laboratory measurements of in-situ samples collected at each site.