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A study on the variations of optical and physical properties of aerosols over a tropical semi-arid station during grassland fire

Kumar, K Raghavendra and Narasimhulu, K and Balakrishnaiah, GB and Reddy, B Suresh Kumar and Gopal, K Rama and Reddy, RR and Satheesh, SK and Moorthy, K Krishna and Babu, S Suresh (2010) A study on the variations of optical and physical properties of aerosols over a tropical semi-arid station during grassland fire. In: Atmospheric Research, 95 (1). pp. 77-87.

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Abstract

The present paper records the results of a case study on the impact of an extensive grassland fire on the physical and optical properties of aerosols at a semi-arid station in southern India for the first time from ground based measurements using a MICROTOPS-II sunphotometer, an aethalometer and a quartz crystal microbalance impactor (QCM). Observations revealed a substantial increase in aerosol optical depth (AOD) at all wavelengths during burning days compared to normal days. High AOD values observed at shorter wavelengths suggest the dominance of accumulation mode particle loading over the study area. Daily mean aerosol size spectra shows, most of the time, power-law distribution. To characterize AOD, the Angstrom parameters (i.e., alpha and beta) were used. Wavelength exponent (1.38) and turbidity coefficient (0.21) are high during burning days compared to normal days, thereby suggesting an increase in accumulation mode particle loading. Aerosol size distribution suggested dominance of accumulation mode particle loading during burning days compared to normal days. A significant positive correlation was observed between AOD at 500 mn and water vapour and negative correlation between AOD at 500 nm and wind speed for burning and non-burning days. Diurnal variations of black carbon (BC) aerosol mass concentrations increased by a factor of similar to 2 in the morning and afternoon hours during burning period compared to normal days.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Elsevier science.
Keywords: Aerosol optical depth; Black carbon mass concentration; Size distribution; Accumulation mode particles
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 19 Jan 2010 09:00
Last Modified: 19 Sep 2010 05:54
URI: http://eprints.iisc.ernet.in/id/eprint/25437

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