Soil emissivity and reflectance spectra measurements

Area of Science:

• Geosciences
• Remote Sensing
• Spectroscopy

Background:

• Soil spectral properties are crucial for remote sensing applications.
• Accurate emissivity measurements are vital for thermal remote sensing of Earth's surface.
• Understanding mineralogical influences on spectral signatures is key.

Purpose of the Study:

• To analyze laboratory reflectance and emissivity spectra of diverse soil samples.
• To compare laboratory-derived emissivity with field measurements using advanced algorithms.
• To validate the accuracy of remote sensing-based emissivity retrieval methods.

Main Methods:

• Collected 11 soil samples from Europe, North Africa, and South America (2002-2008).
• Measured hemispherical reflectance spectra (2.0-14 µm) using Fourier transform infrared spectroscopy.
• Determined mineralogical phases via X-ray diffraction (XRD).
• Calculated emissivity using Kirchhoff's law and compared with field radiometer data (CIMEL CE312-2) processed with ASTER emissivity algorithm.

Main Results:

• Laboratory emissivity spectra were derived from reflectance measurements.
• Field emissivity was obtained using a thermal radiometer and the ASTER algorithm.
• A root mean square error typically below 0.015 was achieved between laboratory and field emissivity measurements.
• High correlation observed between laboratory and field emissivity data.

Conclusions:

• Laboratory spectral analysis provides reliable emissivity data for soils.
• The ASTER temperature and emissivity separation algorithm, combined with field radiometer data, accurately retrieves soil emissivity.
• This validates the use of remote sensing for characterizing soil surface properties globally.