Atmospheric aerosols and air pollution

Abstract

<span style="font-size:12.0pt;line-height: 115%;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">Multiwavelength radiometer measurement of aerosol optical depth (AOD) at ten wavelengths in the visible and near IR is an ongoing programme since 1988 at Mysore (12°N, 76°E), a semi-urban continental area with a population of about 1 million. The analysis of 10-yr data indicates an increase in the spectral AOD which is attributed to the increased air pollution resulting from anthropogenic activities. The pollution related aerosol turbidity parameters <span style="font-size:12.0pt;line-height:115%;font-family:" times="" new="" roman","serif";="" mso-fareast-font-family:fd1228418-identity-h;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">α <span style="font-size:12.0pt;line-height:115%;font-family:" times="" new="" roman","serif";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-in;mso-fareast-language:="" en-in;mso-bidi-language:hi"="" lang="EN-IN">and β are determined graphically from AOD. The size-dependent parameter <span style="font-size:12.0pt; line-height:115%;font-family:" times="" new="" roman","serif";mso-fareast-font-family:="" fd1228418-identity-h;mso-ansi-language:en-in;mso-fareast-language:en-in;="" mso-bidi-language:hi"="" lang="EN-IN">α <span style="font-size:12.0pt; line-height:115%;font-family:" times="" new="" roman","serif";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-in;mso-fareast-language:en-in;="" mso-bidi-language:hi"="" lang="EN-IN">shows a decrease initially and later on an increase. The number density parameter β remains almost a constant throughout the data period. Aerosol size spectrum is retrieved by numerically inverting the AODs, and the aerosol characteristics are estimated. These indicate that <span style="font-size:12.0pt;line-height:115%;font-family:" times="" new="" roman","serif";="" mso-fareast-font-family:fd1228418-identity-h;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">a <span style="font-size:12.0pt;line-height:115%;font-family:" times="" new="" roman","serif";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-in;mso-fareast-language:="" en-in;mso-bidi-language:hi"="" lang="EN-IN">depends on the number of accumulation mode particles, and β on the mass loading.</span></span></span></span></span></span></span>