Derivation of vertical aerosol profiles in lower stratosphere and upper troposphere using twilight photometry

Abstract

A photometer has been designed and developed for observation of the zenith sky illumination during the twilight period to monitor the vertical profile of aerosols. A red gelatin filter centered at 700 mm (50 nm half bandwidth) and RCA 6199 photomultiplier tube were selected for the photometer. The experimental set-up and method of data analysis to derive vertical profile of atmospheric aerosols have been presented. The observations were carried out at tropical location Pathardi(19^o 9'N, 75^o 10' E) during the period 1 Jan. 1993 - 31 Dec. 1994. The intensity parameter, <i>-</i>(<i>I</i>dh)^-1d<i>I</i>,<i> </i>was determined and its changes attributed to the variation in the structure of the atmosphere resulted due to changes in aerosol density. An algorithm is developed for the estimation of vertical profile of aerosols in terms of number density. The estimated vertical

<span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">profile of aerosols compares well with other methods of observations.</span>