Methodologies and protocols for the collection of midwave and longwave infrared emissivity spectra using a portable field spectrometer

The development of highly portable field devices for measuring midwave and longwave infrared emissivity spectra has greatly enhanced the ability of scientists to develop and verify exploitation algorithms designed to operate in these spectral regions. These data, however, need to be collected properly in order to prove useful once the scientists return from the field. Attention to the removal of environmental factors such as reflected downwelling atmospheric and background radiance from the measured signal are of paramount importance. Proper separation of temperature and spectral emissivity is also a key factor in obtaining spectra of accurate shape and magnitude. A complete description of the physics governing the collection of field spectral emissivity data will be presented along with the assumptions necessary to obtain useful sample signatures. A detailed look at an example field collection device will be presented and the limitations and considerations when using such a device will be scrutinized. Attention will be drawn to the quality that can be expected from field measurements obtained and the limitations in their use that must be endured.