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

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 q...

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Bibliographic Details
Published in:Atmospheric research 2010, Vol.95 (1), p.77-87
Main Authors: Kumar, K. Raghavendra, Narasimhulu, K., Balakrishnaiah, G., Reddy, B. Suresh Kumar, Gopal, K. Rama, Reddy, R.R., Satheesh, S.K., Moorthy, K. Krishna, Babu, S. Suresh
Format: Article
Language:English
Subjects:
Accumulation mode particles
Aerosol optical depth
Black carbon mass concentration
Earth, ocean, space
Exact sciences and technology
External geophysics
Meteorology
Particles and aerosols
Size distribution
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Summary: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., α and β) 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 nm 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 ~ 2 in the morning and afternoon hours during burning period compared to normal days.
ISSN:0169-8095
1873-2895
DOI:10.1016/j.atmosres.2009.08.012