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

► BC surface mass concentration exhibited diurnal variation associated with local meteorology. ► Daytime mean BC surface mass concentration was 11 μg m−3. ► Mean BC-AOD estimated in OPAC at 0.5 μm was 0.11. ► Mean shortwave BC radiative forcing at the TOA was +0.94 W m−2. ► BC emissions from IGP and biofuel and fossil fuel combustion contributed majorly to BC loading.