Black carbon scavenging by low-level Arctic clouds

Black carbon (BC) from anthropogenic and natural sources has a pronounced climatic effect on the polar environment. The interaction of BC with low-level Arctic clouds, important for understanding BC deposition from the atmosphere, is studied using the first long-term observational data set of equivalent black carbon (eBC) inside and outside of clouds observed at Zeppelin Observatory, Svalbard. We show that the measured cloud residual eBC concentrations have a clear seasonal cycle with a maximum in early spring, due to the Arctic haze phenomenon, followed by cleaner summer months with very low concentrations. The scavenged fraction of eBC was positively correlated with the cloud water content and showed lower scavenged fractions at low temperatures, which may be due to mixed-phase cloud processes. A trajectory analysis revealed potential sources of eBC and the need to ensure that aerosol-cloud measurements are collocated, given the differences in air mass origin of cloudy and non-cloudy periods. Black carbon in the Arctic has pronounced climatic effects, whilst residing in the atmosphere or after being deposited. Here long-term observations of black carbon inside Arctic clouds are used to study their seasonality, sources and links to other meteorological parameters.

Automated summary

Black carbon has a pronounced climatic effect on the polar environment. This study uses long-term observations of black carbon inside Arctic clouds to investigate its seasonality, sources, and links to other meteorological parameters.