Radiation measurement and remote sensing

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Many devices based on radiative transfer are used for remote sensing of surface characteristics. These include IR cameras, optical pyrometers, satellite sensors and others. All view the radiosity leaving the observed bounding surface. If the surface is not nearly black, then the reflected component of radiosity may be a significant fraction of the surface emission, and the computed surface temperature may be in error. The range of spectral sensitivity of each of these devices is generally selected so that absorption and scattering by media between the detector and the measurement source can be neglected. Finding a spectral "window" is not always possible, in particular for satellite sensing systems, where the atmosphere has scattering particles that cause some attenuation at almost all wavelengths, and fog, smog, and clouds may be present. Because the absorption/scattering properties along the path are not known, this is an application where inverse analysis to determine the attenuation properties of the atmosphere becomes critical. If the environment is at a low temperature compared with the object being measured by the pyrometer, then the radiosity is only dominated by emission from the object, and J = εσT4. The temperature can then be inferred from the pyrometer measurement if the emissivity of the object is known.


Faghri, A., Zhang, Y., and Howell, J. R., 2010, Advanced Heat and Mass Transfer, Global Digital Press, Columbia, MO.

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