Gas plume characterization by passive remote sensing: a

摘要

Abstract: The remote sensing of CO$-2$/ plumes or clouds is made possible by a passive optical method: we analyze the measured radiation to find the plume temperature and concentration which are supposed to be constant in the plume along the measuring optical path. The optical axis is issued from the background which is considered as air at room temperature; the radiation first goes across the CO$-2$/ cloud along an optical path a few meters long then across air volume between the detection apparatus and the CO$-2$/ cloud. We have to take into account the absorptivity of the atmosphere air and the emissivity of the background. Three measuring wavelengths are necessary: one gives us the background luminance, the two others are two CO$-2$/ absorption bands. The selection of these wavelengths requires a spectroscopic simulation of the CO$-2$/ and H$- 2$/O molecules; consequently we have to model the spectroscopic product of the CO$-2$/ emissivity and air transmittance line by line. After identifying the measured luminances from a database we can find the temperature and then the concentration of the CO$-2$/ plume. We are also perfecting too a two wavelengths imaging system using an IR camera to visualize a CO$-2$/ plume over a very short period of time. !4