Remote sensing using midwave and longwave spectroscopy has been shown to be capable of detecting gaseous effluents from a stack plume release. In general, measurements have been made through the plume cross-section. This paper discusses experiments and measurements conducted to examine the relative merits of viewing the plume's cross-section or viewing the plume along the axis of the plume flow. While viewing along the plume's flow axis increases the path length, additional factors such as wind variance and the effects of optically thick cells may begin to appear.
Plume Sensing Direction Considerations