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Measurement of electromagnetic energy flow through a sparse particulate medium:...

Mishchenko, M. (2013), Measurement of electromagnetic energy flow through a sparse particulate medium: A perspective, J. Quant. Spectrosc. Radiat. Transfer, 123, 122-134, doi:10.1016/j.jqsrt.2013.01.006.

First-principle analysis of the functional design of a well-collimated radiometer (WCR) reveals that in general, this instrument does not record the instantaneous directional flow of electromagnetic energy. Only in special cases can a sequence of measurements with a WCR yield the magnitude and direction of the local time-averaged Poynting vector. Our analysis demonstrates that it is imperative to clearly formulate the physical nature of the actual measurement afforded by a directional radiometer rather than presume desirable measurement capabilities. Only then can the directional radiometer be considered a legitimate part of physically based remote sensing and radiation-budget applications. We also emphasize the need for a better understanding of the nature of measurements with panoramic radiometers.

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Radiation Science Program (RSP)