Technical note: High-resolution analyses of concentrations and sizes of black carbon particles deposited on northwest Greenland over the past 350 years - Part 1. Continuous flow analysis of the SIGMA-D ice core using a Wide-Range Single-Particle Soot Photometer and a high-efficiency nebulizer

Ice cores can provide long-term records of black carbon (BC), an important aerosol species closely linked to the climate and environment. However, previous studies of ice cores only analysed BC particles with diameter of <600-850 nm, which could have led to underestimation of BC mass concentrations. Information on the size distribution of BC particles is very limited, and there are no Arctic ice core records of the temporal variation in BC size distribution. In this study, we applied a recently developed improved technique to analyse the BC concentration in an ice core drilled at the SIGMA-D site in northwest Greenland. The improved technique, which uses a modified Single-Particle Soot Photometer and a high-efficiency nebulizer, widens the measurable range of BC particle size. For high-resolution continuous analyses of ice cores, we developed a continuous flow analysis (CFA) system (resolution: 10-40 mm). Coupling of the improved BC measurement technique with the CFA system allows accurate high-resolution measurements of the size distribution and concentration of BC particles with diameter between 70 nm and 4 µm, with minimal particle losses. Using this technique, we reconstructed the size distributions and the number and mass concentrations of BC particles during the past 350 years. On the basis of the size distributions, we assessed the underestimation of BC mass concentrations measured using the conventional method. For the period 2003-2013, the underestimation of the average mass concentration would have been 12%-17% for the SIGMA-D core. [ABSTRACT FROM AUTHOR]