Survey of Military Applications for Fourier Transform Infrared Spectroscopy

In Part 1-Determining Vertical Atmospheric Temperature and Moisture Profiles from Radiance Data and Validating Atmospheric Transmittance Models with a Fourier Transform Infrared (FTIR) Spectrometer, two meteorological applications and one environmental application were investigated. A method to retrieve vertical atmospheric temperature and moisture profiles by applying a least-squares solution to atmospheric radiance observed at the surface in the 4.3-mm carbon dioxide absorption band was analyzed. The method did not work. Weighting functions calculated between 2250 cm-1 and 2400 cm-1 from the surface looking up at a 45-degree angle were a maximum at the surface, so no unique solution for temperature retrieval by height could be determined. Atmospheric radiances, observed under various meteorological conditions and viewing angles, were compared to radiances calculated using the Moderate Resolution Transmittance Code (MODTRAN). The utility of the FTIR spectrometer for environmental monitoring was demonstrated by identifying emissions from a coal-burning plant. Constituent gases identified were CO2, CO, O3, HCl, SO2, and N2O. In Part 2--Spectral Features of Conventional Warhead Explosions, results are presented from a field test where an FTIR spectrometer was used to collect data of conventional warhead explosions from 7 December 1998 to 11 December 1998 at Fallon Naval Air Station NV. Data of controlled detonations of statically displayed Mk 82, Mk 83, and Mk 84 bombs; High-speed Anti-Radiant Missiles (HARM); Tomahawk Land-Attack Missiles (TLAM); and C-4 plastic explosives were collected over the 1800 cm-1 to 6000 cm-1 spectral band at resolutions of 16 cm-1. Spectral plots of the explosions showed there were unique spectral features associated with some warhead detonations. The preliminary results of this effort suggest it may be possible to identify the type of warhead detonated by its spectral signature alone.