Fig. 3: Black carbon (BC) size distributions with different Dc ranges at four sites.

Single particle soot photometers (SP2) observational data from a Nanjing (April), b Maqu, c Tokyo, and d Amazon Tall Tower Observatory (ATTO) sites is used. Circles are the diameter of BC-containing particles (Dp) distributions with four selected BC core size (Dc) ranges. Dashed lines represent the linear regression of each distribution. n(Dp) with each Dc range normalized.