Doctor of Philosophy
Department of Chemistry
Bernardo, Cirilo J.H., Measurement of instrument line shape functions of high-resolution FTIR spectrometers and their application to the analysis of spectra, Doctor of Philosophy thesis, Department of Chemistry, University of Wollongong, 2001. http://ro.uow.edu.au/theses/1867
Analysis of ground-based Fourier transform infrared (FTIR) measurements of the solar radiation transmitted through the atmosphere is an established method for deducing total column amounts and vertical distributions of trace gases in the atmosphere. Such measurements contribute valuable information to the understanding of changes in the earth's atmosphere.
In the analysis of these spectra it is usually assumed that the spectrometer is perfect and that the spectrometer line shape function, also known as the instrument line shape (ILS) function, is ideal. In many cases the ILS function is not ideal and the effects non-ideal ILS on the analysis of spectra has not been firmly established.
In this thesis, a Fourier deconvolution method is developed to measure the instrument line shape function. The ILS retrieval technique is validated and compared with a different and independently developed method. The stability of the ILS over time, the transferability of the ILS to different spectral regions, and the constancy of the ILS changes in measurement conditions are investigated.
Synthetic spectra are used to investigate the effects of non-ideal instrument line shapes on the analysis of spectra. A few cases are studied in depth and it is demonstrated that using a measured ILS function can improve the retrieved total column amounts and vertical distributions (volume mixing ratio profiles or VMR profiles). Ozone VMR profile retrievals are then performed on measured spectra and the results compared with data obtained by ozone sonde. The result is an improvement in the retrieved ozone VMR profiles, which demonstrates the value of measuring ILS functions and employing them in the analysis of ground-based solar FTIR measurements.