Remote detection and quantification of hot molecular combustion products—experimental instrumentation and determination of optimal infrared spectral micro-windows

Aiming at quantitative investigations of molecular combustion products released from high temperature events (HTE) such as forest fires, volcano eruptions, etc., HTE infrared emission spectra and multi-spectral images are measured from which combustion gas parameters like concentrations and temperatures are determined by solution of the inverse radiative transfer problem. The measurement approach permits air-borne or space-borne remote sensing. Airborne instrumentation includes a Fourier transform spectrometer providing high measurement rates and ruggedness by a rotary scan arrangement covering the mid and thermal infrared bands. The optically co-aligned camera system incorporates the visible/near infrared, mid, and thermal infrared bands. In order to extract high accuracy combustion gas concentrations and temperatures from the measured data, the analysis procedures have to be applied to optimal spectral regions denoted ‘micro-windows’. These are determined by simulations employing radiative transfer models and retrieval procedures along with appropriate molecular spectroscopic data bases such as HITRAN and HITEMP. Simulations and results are presented for the analysis of CO2 and CO from a flaming forest fire (1000 K) scene. The spectral window 2391.1–2392.2 cm−1 is best suited for retrieving CO2 column amounts over forest fires and the spectral region 2127.25–2128.25 cm−1 for the CO column. The H2O column needed for CO retrieval, is retrieved in 2142–2142.6 cm−1.