Vertical profile variations of NO₂<i> </i>and O₃ using slant column density observations during twilight period

Abstract

An algorithm developed to derive the vertical profiles of atmospheric species from their slant column density measurements using twilight spectroscopy is discussed. The algorithm has been tested by using the slant column density measurements at polar station, Reykjavik (64°N, 22.6°W) and tropical station, Pune (l8.53°N, 73.85°E). The vertical profiles of NO₂ and O₃ are retrieved by considering slant column densities for ten different solar zenith angles and ten different atmospheric layers of equal thickness. These vertical profiles are

used to differentiate the tropospheric and stratospheric contribution of NO₂ and O₃ . The observations of &nbsp;NO₂ at polar station and at tropical station showed frequent higher values of tropospheric concentrations due to pollution episodes and are not correlated with stratospheric NO₂ and O_3. The correlation between total column density variations of NO₂ and O₃ is not observed; however, the stratospheric variations of NO₂ and O₃ showed good correlation.