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In this research, it is hypothesized that recently developed theoretical considerations of atmospheric radiative transfer in horizontally in-homogeneous atmospheres can be applied to the remote measurement of anthropogenic plumes. To this end, a MAX-DOAS spectrometer, designed around a BandW-TEK BTU142 spectrometer was constructed and characterized. It was found that the MAX-DOAS spectrometer has a measured resolution of 0.282 nm, and a noise level of 178 counts at 75% pixel saturation, sufficient to resolve accurately the absorptions of important atmospheric species, including SO2, NO2, HCHO, and O4. The theory of MAX-DOAS spectral analysis was examined in detail, in particular the processing of reference absorption cross-section spectra for use in regression analyses of scattered solar radiation. For the purposes of inversion, optimal estimation software was designed and investigated for suitability in retrieving vertical profiles of atmospheric species. This software is shown to perform well under conditions of both typical and non-typical noise levels using synthetic spectral data and known profiles of three atmospheric species. Furthermore, an extensive examination of the residuals of DOAS spectral analysis was performed, to validate the assumption of normally distributed errors in the inversion process. Investigated methodologies were applied to spectral data collected over nine days in 2008 in the Upper Ohio River Valley. Aerosol extinction coefficient profiles were successfully retrieved, with an average peak value of 0.549 km-1. For the same measurement period, in-plume measurements of SO2 and NO2 concentration from a coal-fired power plant were conducted using recently developed methodologies to account for in-plume solar radiative transfer effects. |
