Distinct surface response to black carbon aerosols

Despite a reduction in the downward radiation energy, the surface air temperature still increases by 0.25 +/- 0.08 K because of less efficient energy dissipation, manifested by reduced surface sensible (-2.88 +/- 0.43 W m(-2) (W m(-2))(-1)) and latent heat flux (-1.54 +/- 0.27 W m(-2) (W m(-2))(-1)), as well as a decrease in Bowen ratio (-0.20 +/- 0.07 (W m(-2))(-1)). Such reductions of turbulent fluxes can be largely explained by enhanced air stability (0.07 +/- 0.02 K (W m(-2))(-1)), measured as the difference of the potential temperature between 925 hPa and surface, and reduced surface wind speed (-0.05 +/- 0.01 m s(-1) (W m(-2))(-1)).

The enhanced stability is due to the faster atmospheric warming relative to the surface, whereas the reduced wind speed can be partially explained by enhanced stability and reduced Equator-to-pole atmospheric temperature gradient. These rapid adjustments under BC forcing occur in the lower atmosphere and propagate downward to influence the surface energy redistribution and thus surface temperature response, which is not observed under greenhouse gases or scattering aerosols.

Our study provides new insights into the impact of absorbing aerosols on surface energy balance and surface temperature response.