| dc.description.abstract | The ship signature model ShipIR/NTCS has been selected as a NATO standard. In 2001 several nations, including
Norway, participated in the SIMVEX field trial arranged by NATO in Canada for validation of this model. The
measurements were performed on a research vessel under different meteorological conditions, when the ship was sunlit
and shaded, and also at night. Knowledge of the spectral distribution of signatures is essential when comparing images
acquired with different IR cameras. This report presents spectral results from our high resolution FTIR
spectroradiometer, Bomem DA5. Most of our measurements were made with a resolution of 0.5 wavenumbers. Using
in-house software that enables correction of non-ideal properties of the spectroradiometer, we obtained improved
absolute precision of calibrated spectra.
The FTIR results are most interesting for sources with strong spectral variations, like the ship's plume, sunlit surfaces
and sea and sky backgrounds. We also measured the ship in positions giving specular sun reflection. Sea and sky
backgrounds were measured at different elevations, and the sea spectra show a significant contribution from sky
reflection. Results from our spectral measurements have been compared with ShipIR/NTCS predictions. By comparing
the results from plume measurements with simulated spectra, using the Fascode atmospheric model, we have estimated
the plume temperature and the concentration of the most important IR contributing molecules. | en_GB |