Relationship between black carbon and associated optical, physical and radiative properties of aerosols over two contrasting environments

Intra-seasonal variability of black carbon aerosols over a coal field area at Dhanbad, India

“…Almost an identical diurnal feature was observed in all the seasons, but with varying amplitudes. Similar type of findings for BC variation has been reported earlier in India and abroad (Allen et al, 1999;Tripathi et al, 2005;Latha and Badarinath, 2003;Tiwari et al, 2013a;Safai et al, 2013Safai et al, , 2014; reference therein). In the winter period, the concentrations of BC mass were constant during night as compared to other seasons.…”

“…2). The monthly mass BC concentrations fluctuated between 3.9 (August, 2012) and 9.3 (January, 2012) μg m −3 and behaved in a pattern which was in agreement with another measured urban sites of Delhi, Kanpur, Pune, and Karachi (Tiwari et al, 2013a;Dey and Tripathi, 2008;Safai et al, 2014;Dutkiewic et al, 2009). During the study period, it was observed that~70% higher concentrations of BC were during the dry period (December-April) than wet period (middle of June-to-September; mean: 4.6 μg m −3 ).…”

“…The second peak (not significant as morning) was found during 19:00 to 21:00 LT (evening) except winter. This large with significant variability of BC is considered to be due to the impact of boundary layer dynamics as well as changes in emission sources mainly automobile exhaust over urban region as well as biomass/biofuel combustion over rural environment which are the major sources for BC (Badarinath et al, 2006(Badarinath et al, , 2007Sharma et al 2010;Tiwari et al 2013a;Safai et al, 2014). Almost an identical diurnal feature was observed in all the seasons, but with varying amplitudes.…”

“…The uncertainty involved in the BC mass concentration measurements was~10%. Further details of the instrument and the measurement techniques can be found elsewhere (Hansen et al, 1984;Tiwari et al, 2013a;Safai et al, 2014).…”

“…According to the Intergovernmental Panel on Climate Change (IPCC, 2007), the global mean clear sky radiative forcing of BC was 0.23 ± 0.25 W m −2 , which is nearly half of the value of methane and the second most important greenhouse gas after carbon dioxide (CO 2 ). Primary emitted BC mass aerosols tend to be hydrophobic as they age in the atmosphere and tend to acquire a hydrophilic coating (Safai et al, 2014). BC aerosol, mixed with other hydrophilic particles, can also affect the concentrations of the number of cloud droplets and cloud microphysical properties and even reduce precipitation (Chen et al, 2010;Bauer et al, 2010;Ramanathan et al, 2011).…”