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Diurnal and Monthly Variation of Aerosol Optical Depth and Angstromís Parameters in Kathmandu Valley, Nepal

Author Affiliations

  • 1Institute of Engineering, Thapathali Campus, Tribhuvan University, Kathmandu, Nepal
  • 2Institute of Engineering, Tribhuvan University, Lalitpur, Nepal
  • 3Central Department of Physics, Tribhuvan University, Kathmandu, Nepal
  • 4Institute of Engineering, Tribhuvan University, Lalitpur, Nepal
  • 5Institute of Engineering, Tribhuvan University, Lalitpur, Nepal

Res.J.chem.sci., Volume 6, Issue (2), Pages 40-44, February,18 (2016)


Aerosol optical depth (AOD) is measured at five optical channels by Microtops II Sunphotometer at Institute of Engineering, Pulchowk, Lalitpur, Nepal from November 2011 to March 2013 in clear non cloudy days. The Angstromís turbidity parameters, α and β, have been calculated from AOD measurements and their variation have been analyzed on daily and monthly basis. The result shows that value of α and β varies throughout the day because of the change in meteorological parameters. It is observed that during the measurement period, the monthly average minimum and maximum values of a are 0.24 and 1.27 in September 2011 and December 2012 respectively. Likewise the value of β is 0.16 in December 2012 and 0.43 in April 2012. The variation between the parameters a and β is observed in anti-correlation throughout the day during all months indicating continuous distribution of the fine and coarse particles.


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