Aircraft Measurements of Black Carbon in the Boundary Layer over the North China Plain

Abstract. Black carbon aerosol (BC) is the principle absorber to modify the shortwave radiative balance between the lower atmosphere and the surface in polluted environment, which was in-situ characterized by aircraft measurements using a single particle soot photometer (DMT inc., SP2) throughout the boundary layer up to 3 km over the North China Plain around Beijing megacity. The flights were conducted in both hot season (late spring, Apr.–Jun. 2012, surface temperature > 20 °C, 10 flights) and cold season (winter, Dec. 2016, surface temperature Fcoating,EZ), however showed seasonally different behaviors in terms of core size (MMDPBL > MMDEZ in late spring, but the opposite in winter). These results provide the basis to evaluate the BC direct radiative forcing in the polluted planetary boundary layer over this region and also the indirect forcing of BC by interacting with low-level clouds.