Retrieval of ozone profiles over Antarctica using laser heterodyne system

The paper reports that a highly sophisticated laser heterodyne system is being designed and developed at the National Physical Laboratory, New Delhi, to monitor vertical profiles of ozone and other related trace species over Antarctica. The retrieval technique developed and tested to obtain vertical profiles of ozone from the laser heterodyne system measurements using inversion technique, based on inverse solution of radiative transfer equation for Antarctic environmental conditions has been discussed. The inverse technique so developed has been tested using actual vertical profiles of ozone obtained on 23 Aug. 1989 and 20 Oct. 1989 at McMurdo station. The ozone absorption line selected is 1043.1775 per cm, which is near the P(24) line of CO2 laser in 9.6 microns band. Various line parameters, such as half-width, line strength, low energy level, etc. were computed using AFGL HITRAN database, 1986. In all, 16 frequency channels were selected and spectral intensity for each channel was computed using O3 profiles obtained at McMurdo station. An initial guess profile was assumed and corresponding to this profile the spectral intensity of each channel was computed and compared with those obtained by actual profiles. The initial guess profile was modified till the two sets of spectral intensities match with each other. The retrieved profiles compare well with the actual O3 profiles.