Inter-Comparison of Field- and Laboratory-Derived Surface Emissivities of Natural and Manmade Materials in Support of Land Surface Temperature (LST) Remote Sensing

Remote Sensing

Martin Wooster¹  MarkJ. Grosvenor¹  ThomasP. F. Dowling¹  MarkC. de Jong¹  James Johnson¹  MaryF. Langsdale¹  Gerardo Rivera²  WilliamR. Johnson²  SimonJ. Hook² 

[1] NERC National Centre for Earth Observation (NCEO), c/o Department of Geography, King’s College London, London WC2B 4BG, UK;National Aeronautics and Space Administration-Jet Propulsion Laboratory (NASA-JPL), 4800 Oak Grove Drive, Pasadena, CA 91109, USA;

关键词: land surface temperature;    land surface emissivity;    measurement uncertainties;    emissivity box method;    Fourier transform infrared spectrometer;    portable spectrometer;   

DOI  :  10.3390/rs12244127

来源: DOAJ

【 摘 要 】

Correct specification of a target’s longwave infrared (LWIR) surface emissivity has been identified as one of the greatest sources of uncertainty in the remote sensing of land surface temperature (LST). Field and laboratory emissivity measurements are essential for improving and validating LST retrievals, but there are differing approaches to making such measurements and the conditions that they are made under can affect their performance. To better understand these impacts we made measurements of fourteen manmade and natural samples under different environmental conditions, both in situ and in the laboratory. We used Fourier transform infrared (FTIR) spectrometers to deliver spectral emissivities and an emissivity box to deliver broadband emissivities. Field- and laboratory-measured spectral emissivities were generally within 1–2% in the key 8–12 micron region of the LWIR atmospheric window for most samples, though greater variability was observed for vegetation and inhomogeneous samples. Differences between laboratory and field spectral measurements highlighted the importance of field methods for these samples, with the laboratory setup unable to capture sample structure or inhomogeneity. The emissivity box delivered broadband emissivities with a consistent negative bias compared to the FTIR-based approaches, with differences of up to 5%. The emissivities retrieved using the different approaches result in LST retrieval differences of between 1 and 4 °C, stressing the importance of correct emissivity specification.

【 授权许可】

Unknown