• P D SAFAI

      Articles written in Journal of Earth System Science

    • Characterisation of particulate matter at a high-altitude site in southwest India: Impact of dust episodes

      P BUCHUNDE P D SAFAI S MUKHERJEE P P LEENA D SIINGH G S MEENA G PANDITHURAI

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      Observations on a particulate matter $\rm{(PM_{10}}$ and $\rm{PM_{2.5})}$ were carried out during March 2015 to February 2017 over a high-altitude location Mahabaleshwar in the Western Ghats region in southwest India. Apart from temporal variation of PM and the ratio of $\rm{PM_{2.5}/PM_{10}}$, impacts of local meteorological parameters on the concentration of PM are examined. $\rm{PM_{10}}$ showed a maximum concentration during pre-monsoon, whereas $\rm{PM_{2.5}}$ showed it in winter. The monsoon season showed the lowest concentrations for both $\rm{PM_{10}}$ and $\rm{PM_{2.5}}$. Concentrations were significantly reduced in 2016 due to the washout effect from enhanced rainfall during that year. Diurnal variations of PM were related to the variation in a planetary boundary layer, mountain valley winds as well as changes in different local sources. Dominance of primary particles was observed from the $\rm{PM_{2.5}/PM_{10}}$ ratio. The Central Pollution Control Board (CPCB) threshold limit for PM was exceeded on several days mainly during pre-monsoon due to transported dust from the Arabian Peninsula and Thar Desert apart from an increase in the tourist activity. A typical case for transported dust event during March 2016 is studied. Organics and sulphate particles showed a significant enhancement during dust event. Overall, the study indicated emissions from mixed sources for PM from local as well as distant source regions over Mahabaleshwar.

    • Black carbon aerosols over a semi-arid rain shadow location in Peninsular India: Temporal variability and sources

      P S SOYAM P D SAFAI S MUKHERJEE K TODEKAR S BANKAR D GURNULE N MALAP T PRABHAKARAN

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      Continuous measurements of absorbing carbonaceous aerosol termed as black carbon (BC) have been carried out during April 2017 to March 2018 over Solapur, a semi-arid, rain shadow location in Peninsular India using a multi-wavelength Aethalometer (AE-33). Statistically significant higher values of BC were observed during the dry period (December–May, mean BC 4.3$\pm$ 1.2 $\mu$g m$^{-3}$) as compared to the wet period (June–October, mean BC 1.0 $\pm$ 0.15 $\mu$g m$^{-3}$). Hourly variation depicted an almost similar pattern in both wet and dry periods with a dominant morning peak followed by afternoon low and then a heightened plateau during the evening to midnight hours. The absorbing Angstrom exponent (AAE) value was 1.36 $\pm$ 0.16 and 1.10 $\pm$ 0.22, respectively, during dry and wet periods with an annual mean of 1.22 $\pm$ 0.23. The source apportionment of BC using the Aethalometer model depicts the dominance of fossil fuel burning throughout the year especially high during the wet period (89$\pm$ 11% to total BC) whereas biomass burning contributed significantly during the dry period (30$\pm$ 14% to total BC). The observed temporal variation of BC was mainly due to the varying strength of BC emission sources and changes in local meteorological parameters. In addition, long-range transport from other regions might have also contributed during certain periods as seen from the cluster and concentration weighted trajectory (CWT) analysis.

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