Molecular Spectroscopy in Highly Complex Inhomogeneous and Unpredictable Scenes - Modelling and Parameter Retrieval for Remote Analysis of Hot Molecular Combustion Products

Abstract

There is an increasing demand for remote sensing methods for reliably detecting and analysing hot molecular combustion products, applying spaceborne sensor systems. Only such an approach can enable a permanent and worldwide observation, needed for monitoring and mitigation of desasters, but also for quantitative analysis of climate relevant gases being produced, for example, by a huge number of fires worldwide. The potential of molecular spectroscopy for quantitative gas analysis and even for identification of spatial parameter profiles, such as gas temperature and concentration along the line of sight, is well known. For fire analysis, however, the key challenge is that the spectrometer is observing a highly complex, inhomogeneous and unpredictable scene. Thus, exact modelling, as usually required for exact parameter retrieval, is impossible in this case. A coal fire was ignited at a DLR test site to examine the potential of remote sensing methods for complex scenes as described above. The gases of interest were CO and CO2 above all, but also NO and NO2. The result is, that some essential gas parameters such as temperature and column densities, but also vertical profiles of gas temperature and concentration can be determined, using appropriately simplifying modelling approaches. The experiment was as such very promising for future airborne or spaceborne measurements.