Spectral and spatial measurements of atmospheric aerosol clouds with a hyperspectral sensor

Along with rising concerns about the global warming and its long term consequences, the need for a better global radiative balance model increases. While the global impact of the greenhous(1)e trace gases is well understood, the radiative forcing of the various natural and manmade aerosols remains uncertain, especially in the IR spectral band. Studying the optical properties of large scale dust loadings in the atmosphere directly is difficult due to the vast uncertainties about their composition and size distributions. Furthermore, the chemical composition of a dust grain is linked to its size. One of the methods to bypass these inherent difficulties is to study anticipated radiative effects with a clearly defined simulant that is well characterized both chemically and by its particles size distribution. In this presentation we show results from spectral and spatial measurements of such aerosol plumes composed of silicone oil droplets. These measurements expand and improve our knowledge of the spectral signature of aerosol clouds obtained in the IR spectral band. Our previous work presented measurements carried out with a non-imaging spectro-radiometer only near the release point. In this article, we show experimental data obtained by a hypesrspectral sensor which enabled us, for the first time to perform a simultaneous measurement of an aerosol cloud, both in the spectral and the spatial domains. These results were compared to a radiative transfer model, and yielded an excellent agreement between the predicted and the measured spectral signatures. The proposed model can be used for the prediction of the optical properties of dust clouds in the atmosphere as well as assessing more accurately their impact on global climate change.