Sources and radiative effects of wintertime black carbon aerosols in an urban atmosphere in east India

S. Verma, S. K. Pani, S. N. Bhanja

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30 Scopus citations

Abstract

We carried out an analysis of black carbon (BC) surface mass concentration, its radiative effects, and sources of origin in an urban atmosphere in east India, during winter season, through ground-based measurements and application of modelling tools. BC surface mass concentration exhibited diurnal variation with their higher values and a larger variability during evening to early morning hours than during daytime (1100-1600h, Local Time, LT) hours. Daytime mean surface BC mass concentration and BC mass fraction in total aerosol (size range 0.23-20μm) and in submicronic aerosol (size range 0.23-1μm) during the study period, corresponding to the well-mixed atmospheric layer were 11μgm-3, 3-10%, and 9-16% respectively. The mean BC optical depth (BC-AOD) and BC-AOD fraction at 0.5μm were estimated in an optical model as 0.11 and 13% respectively. Mean shortwave aerosol radiative forcing due to BC at top-of-atmosphere (TOA) during the study period was found to be +0.94Wm-2, which is about 59% the global mean radiative forcing due to carbon-dioxide gases. Estimates from BC simulations in a general circulation model showed BC surface concentration and BC optical depth in east India are primarily attributed to emissions from biofuel and fossil fuel combustion. Most of BC surface concentration (95%) and BC optical depth (60%) are contributed by emissions arising from the Indo-Gangetic plain (IGP) but there is a significant influence to BC columnar loading through elevated transport channels attributed mainly to emissions from open biomass burning from distant regions outside IGP.

Original languageEnglish
Pages (from-to)260-269
Number of pages10
JournalChemosphere
Volume90
Issue number2
DOIs
StatePublished - Jan 2013

Keywords

  • Aerosol optical depth
  • Aerosols
  • Black carbon
  • Emission sources
  • Radiative effects
  • Radiative forcing

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