Black Carbon measurements during the 2013 Flight to the North Pole
Dr. Griša Močnik, Aerosol d.o.o.
Combustion of carbonaceous fuels for the production of energy results in the emission of particulate air pollutants, including considerable amounts of light absorbing carbonaceous aerosols. These exhibit very large optical absorption across the short-wave optical spectrum. Aerosolized black carbon (BC) is a unique primary tracer for combustion emissions; it is inert and can be transported over large distances (Bodhaine 1995, Weigum 2012), even though its lifetime in the atmosphere is relatively short and measured in days or weeks. BC affects the optical properties of the atmosphere when suspended, leading to local heating or cooling, depending on the processes involved (Menon 2002). It is recognized as the second most important cause of global warming with a contribution between 20% and 40% with a significant regional heterogeneity (Ramanathan 2008). The Arctic is especially vulnerable to the effects of BC. The warming continues after deposition of BC on the snow and ice due to the darkening of the otherwise reflective surface.
The Arctic has seen unprecedented melting this year and also in the past years (NSIDC 2012), potentially opening new shipping routes. Ship engines emit large amounts of BC and the deposition of BC has a positive feedback – as more ice melts, more ships will use the new lanes. Measurements of BC in the Arctic have been performed for a long time (Hansen 1989), but with very limited spatial coverage, and measurements of vertical profiles have been performed only recently (Ferrero 2012).
We have demonstrated during the GLWF2012 round-the-world campaign that a lightweight aircraft can provide valuable information on BC concentrations, their regional heterogeneity and vertical profiles with a minor payload and for a fraction of the cost associated with large airborne platforms (Močnik 2012). In late spring 2013 during the flight to the North Pole the same measurements will be carried out. We have modified the aircraft to include an aerosol inlet and a prototype Aethalometer will be used to measure BC. Additional auxiliary measurements will be carried out onboard. We will attempt to measure the effect of the shipping on the BC concentrations in the Arctic during the flight, and analyze the spectral dependence of aerosol absorption to determine the sources (Sandradewi 2008). During flight plumes of pollution might be encountered and using back trajectories possible source regions will be identifed.
Major scientific study finds that the effect of Black Carbon on climate is much greater than previously believed. Results show that Black Carbon is the second climate forcing agent with contribution 2/3 that of CO2. The results have been recently published in JGR with the forcing estimated at +1.1 W/m2.
The warming caused by the regional forcing will be particularly noticeable in the future at high latitudes in the northern hemisphere due to the deposition of Black Carbon on snow and ice.
The article is freely available at:
T. Bond et al., Bounding the role of black carbon in the climate system: A scientific assessment, JGR 2013, DOI: 10.1002/jgrd.50171
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