Abstract
Abstract. Black carbon (BC) is an important climate-forcing agent that affects snow albedo. In this work, we present a record of refractory black carbon (rBC) variability, measured from a 20 m deep snow and firn core drilled in West Antarctica (79∘55′34.6′′ S, 94∘21′13.3′′ W, 2122 m above sea level) during the 2014–2015 austral summer. This is the highest elevation rBC record from West Antarctica. The core was analyzed using the Single Particle Soot Photometer (SP2) coupled to a CETAC Marin-5 nebulizer. Results show a well-defined seasonality with geometric mean concentrations of 0.015 µg L−1 for the wet season (austral summer–fall) and 0.057 µg L−1 for the dry season (austral winter–spring). The core was dated to 47 years (1968–2015) using rBC seasonality as the main parameter, along with sodium (Na), sulfur (S) and strontium (Sr) variations. The annual rBC concentration geometric mean was 0.03 µg L−1, the lowest of all rBC cores in Antarctica referenced in this work, while the annual rBC flux was 6.25 µg m−2 a−1, the lowest flux in West Antarctica rBC records. No long-term trend was observed. Snow albedo reductions at the site due to BC were simulated using SNICAR online and found to be insignificant (−0.48 %) compared to clean snow. Fire spot inventory and BC emission estimates from the Southern Hemisphere suggest Australia and Southern Hemisphere South America as the most probable emission sources of BC to the drilling site, whereas HYSPLIT model particle transport simulations from 1968 to 2015 support Australia and New Zealand as rBC sources, with limited contributions from South America. Spectral analysis (REDFIT method) of the BC record showed cycles related to the Antarctic Oscillation (AAO) and to El Niño–Southern Oscillation (ENSO), but cycles in common with the Amundsen Sea Low (ASL) were not detected. Correlation of rBC records in Antarctica with snow accumulation, elevation and distance to the sea suggests rBC transport to East Antarctica is different from transport to West Antarctica.
Highlights
Black carbon (BC) is a carbonaceous aerosol formed during incomplete combustion of biomass and fossil fuels, characterized by strong absorption of visible light and resistance to chemical transformation (Petzold et al, 2013), and it plays an important role in the climatic system by being able to alter the planetary albedo (McConnell et al, 2007; Ni et al, 2014).BC-containing aerosols are the species most commonly identified as being short-lived climate forcers, along with methane and ozone (AMAP, 2015)
The first uncertain year is located at 6.18 m, where S and nssS / Na peak, but no full cycle is observed in the refractory black carbon (rBC) record
South American influence on the TT07 drilling site, on the other hand, is restricted to the higher-latitude countries (Chile, Argentina), as shown in the individual trajectories of clusters 2, 3 and 5 (Fig. 10). This suggests that South American fires are not significant contributors to the rBC concentrations observed at the TT07 site when considering only tropospheric transport
Summary
Black carbon (BC) is a carbonaceous aerosol formed during incomplete combustion of biomass and fossil fuels, characterized by strong absorption of visible light and resistance to chemical transformation (Petzold et al, 2013), and it plays an important role in the climatic system by being able to alter the planetary albedo (McConnell et al, 2007; Ni et al, 2014). There are several records of SH paleo-biomass burning, there are only a few publications on BC variability in ice cores from Antarctica. Some of those are focused on centennial–millennial timescales (Arienzo et al, 2017; Chýlek et al, 1992) and others on annual to decadal scales (Bisiaux et al, 2012a, b; Pasteris et al, 2014). In this work we present a new West Antarctic high-temporalresolution rBC snow and firn core record.
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