Infrared surface spectral emissivity is a fundamental property of terrestrial materials, important in a host of environmental applications ranging from mineral mapping to land cover change determination, and in particular the remote sensing of land surface temperature (LST). Surface spectral emissivity has also been used to inform the chemical and physical composition determination of terrestrial and planetary materials. Multiple laboratories have now developed facilities for determining the surface spectral emissivity of samples from reflected infrared radiation measurements (making use of Kirchhoff’s Law), with the results often made publicly available such as in the ECOSTRESS (Ecosystem Thermal Radiometer Experiment on Space Station) spectral library. However, until now there has been relatively little work conducted in evaluating the uncertainties in these types of measurements and the consistency of measurements made in different laboratories. Here we intercompare surface spectral emissivity measurements in a ‘round-robin’ exercise using identical samples at 7 different international laboratories. During this exercise, 4cm-1 spectral resolution emissivity spectra were determined for three samples: distilled water, which has a uniformly high spectral emissivity, and two artificial samples constructed from gold and aluminium sheets laminated in polyethylene (PE), which show respectively both Lambertian and specular characteristics along with widely varying emissivity features across the 2.5 – 14 μm region. Here we present first results from the round-robin intercomparison exercise and discuss the implications for the uncertainty of surface spectral emissivity values determined in the laboratory and for the satellite LST products and LST field validation studies that rely on them.
|Publication status||Published - 15 May 2020|
|Event||ESA Living planet symposium - Milan, Italy|
Duration: 13 May 2019 → 17 May 2019
|Conference||ESA Living planet symposium|
|Period||13/05/19 → 17/05/19|