We operate a multi angle absorption photometer MAAP (Model 5012, Thermo Electron Corp.). which is in operation since March 2006 ongoing. This instrument measures atmospheric light absorption by aerosol (mainly caused by black carbon, BC). To this end, ambient aerosol was sampled on a glass filter tape. The measured absorption coefficients abs(637) refer to a wavelength of 637 nm. Raw data were originally sampled in one-minute resolution. Finally, hourly averaged MAAP data are presented here. We also provide BC concentrations (ng/m³) derived from the absorption coefficients using the specific BC attenuation cross section (QBC) of 6.6 m²/g.

Important notice: BC concentrations are extremely low at Neumayer, typically lower than the instrumental noise level referring to 1 hour averages (between 0.04 and 0.05 Mm-1). Notwithstanding, we archived hourly averages, but one has to be aware that negative values may not be removed when smoothing the data or when calculating averages with lower temporal resolution, otherwise the results would exhibit a substantial positive bias!