Estimates of mass absorption cross sections of black carbon for filter-based absorption photometers in the Arctic

Abstract. Long-term measurements of atmospheric mass concentrations black carbon (BC) are needed to investigate changes in its emission, transport, and deposition. However, depending on instrumentation, parameters related BC such as aerosol absorption coefficient (babs) have been measured instead. Most ground-based babs the Arctic made by filter-based photometers, including particle soot photometers (PSAPs), continuous light (CLAPs), Aethalometers, multi-angle (MAAPs). The can be converted (MBC) assuming value cross section (MAC; MBC= babs/ MAC). accuracy conversion MBC has not adequately assessed. Here, we introduce a systematic method for deriving MAC values from these instruments independently MBC. In this method, was with photometer heated inlet (COSMOS). COSMOS-derived (MBC (COSMOS)) is traceable rigorously calibrated single (SP2), absolute (COSMOS) demonstrated previously about 15 % Asia Arctic. necessary conditions application high correlation long-term stability regression slope, which denoted MACcor (MAC derived correlation). general, babs–MBC correlations were (r2= 0.76–0.95 hourly data) at Alert Canada, Ny-Ålesund Svalbard, Barrow (NOAA Observatory) Alaska, Pallastunturi Finland, Fukue Japan stable up 10 years. We successfully estimated (10.8–15.1 m2 g−1 wavelength 550 nm instruments, used obtain error-constrained estimates sites even past, when COSMOS made. Because consistent each other, they applicable study spatial temporal variation evaluation performance numerical model calculations.