ANALYSIS OF HIGH RESOLUTION SPECTRA IN THE PRESENCE OF CHANNEL SPECTRA AND PHASE ERRORS USING NONLINEAR LEAST SQUARES

$^{1}$Y. S. Chang And J. H. Shaw, Appl. Spectrosc., 31, 213 (1977).Author Institution:Nonlinear least squares spectral curve $fitting^{1}$ has been used to analyze a narrow spectral region (1603 – $1607.4 cm^{-1}$) from a series of solar occulation spectra collected with a high resolution (=$0.02 cm^{-1}$) interferometer. These spectra were used to retrieve the vertical mixing ratio profiles for $NO_{2}$ and $H_{2}O$ above 16 km. After standard phase correction and removal of the secondary interferogram, some residual phase error and channel spectrum distortion remained and interfered with the profile retrievals. By explicitly including both these effects in the spectral model and simultaneously retrieving the phase error and channel spectrum parameters a long with the other parameters (background level, instrument resolution, frequency shift, $NO_{2}$ and $H_{2}O$ profiles and relevant temperatures) improved profiles were obtained