Light-absorbing aerosols affect atmospheric radiation, dynamics, and precipitations through shortwave absorption in the atmosphere and snowpack. Black carbon (BC) is considered the most significant contributor to global shortwave absorption among all the known light-absorbing aerosol components. In analyses and predictions of BC’s lifecycle and climate effects, multiscale field observations are needed to test the fundamental assumptions in the climate model. In situ measurements, the focus of this review, fill the gap of observational information accessible from remote sensing and laboratory analyses. This article reviews historical backgrounds, recent advances in in situ measurements of BC, and the resulting observational findings used to update the assumptions in climate models and remote sensing. Finally, we raise open problems that demand a rethinking and future investigation.Illustrating the physical principle of detecting the light-absorbing black carbon and iron oxides
aerosol particles using the single-particle laser-induced incandescence