Impact of Diwali festival on aerosol optical properties over an Urban city, Ahmedabad (India)

Abstract

An attempt has been made to investigate changes in the characteristics of aerosol optical properties induced during Diwali/ New Year celebrations of 2012 over an urban city, Ahmedabad (India). Ground based measurements of average Aerosol Optical Depth (AOD) were carried out using a Microtops-II at Physics Department, Gujarat University, Ahmedabad during 10thto 16thNov, 2012. AOD on the day just after Diwali is found to increase significantly; around 75% compared to pre-Diwali days for visible wavelength, remained at higher level for one more day (next day of New Year). Turbidity factor (β) also changed considerably, to a high value of 0.34 on the next day of Diwali, indicating a significant increase in aerosol loading associated with Diwali/ New Year festivities. Normal anti-correlation between Angstrom exponent (α) and turbidity parameter (β) is not seen on days following Diwali. The AOD and β values in the evening of the next day of Diwali increased to about 164% and 171% respectively compared to pre-Diwali days evenings; such an increase associated with the festivities has not been reported at any part of the country. Spectral variation of AOD also shows a significant change in the pattern during following two days of celebrations compared to pre-Diwali days. It is seen to follow power law more closely. Significant increase in AOD and change in spectral pattern suggest an increase of fine/accumulation mode particles due to Diwali/ New Year festivities.