Measurement of black carbon at Syowa station, Antarctica: seasonal variation, transport processes and pathways

Abstract

Abstract. Measurement of black carbon (BC) was carried out at Syowa station Antarctica (69° S, 39° E) from February 2004 until January 2007. The BC concentration at Syowa ranged from below detection to 176 ng m−3 during the measurements. Higher BC concentrations were observed mostly under strong wind (blizzard) conditions due to the approach of a cyclone and blocking event. The BC-rich air masses traveled from the lower troposphere of the Atlantic and Indian Oceans to Syowa (Antarctic coast). During the summer (November–February), the BC concentration showed a diurnal variation together with surface wind speed and increased in the katabatic wind from the Antarctic continent. Considering the low BC source strength in the Antarctic continent, the higher BC concentration in the continental air (katabatic wind) might be caused by long range transport of BC via the free troposphere from mid- and low- latitudes. The seasonal variation of BC at Syowa had a maximum in August, while at the other coastal stations (Halley, Neumayer, and Ferraz) and the continental station (Amundsen-Scott), the maximum occurred in October. This difference may result from different transport pathways and scavenging of BC by precipitation during the transport from the source regions. During the austral summer, long-range transport of BC via the free troposphere is likely to make an important contribution to the ambient BC concentration. The BC transport flux indicated that BC injection into the Antarctic region strongly depended on the frequency of storm (blizzard) conditions. The seasonal variation of BC transport flux increased by 290 mg m−2 month−1 in winter–spring when blizzards frequently occurred, whereas the flux decreased to lower than 50 mg m−2 month−1 in the summer with infrequent blizzards.

Do anthropogenic, continental or coastal aerosol sources impact on a marine aerosol signature at Mace Head?

“…The mass attenuation coefficient of Aethalometer AE-16 was 16.8 m 2 g −1 . Junker et al (2006) indicated that thermo-optical method suggested a much higher value (35 m 2 g −1 ) in clean marine sector samples, which would result in an even lower threshold BC value of 24 ng m −3 and the typical clean marine sector values of only 5-10 ng m −3 , which would then be comparable to BC values from the pristine environments (Hansen et al, 1988;Hara et al, 2008;Sciare et al, 2009;Shank et al, 2012). In summary it suggests that EBC values reported for MH (Mace Head) are most likely systematically biased high.…”

Spatial and temporal variability of snow chemical composition and accumulation rate at Talos Dome site (East Antarctica)

“…This evidence can mean that nitrate sources (especially stratosphere-troposphere transport and re-emission of NO x from the snow surface) are more intense in this season. In addition, we have to note that meridional transport of nitrate and sulfate from lower latitudes is more efficient in summer, due to the weakening of the polar vortex (Hara et al, 2008). Finally, higher temperature and intense solar irradiation make more efficient the photochemical oxidation of NO x and SO 2 to nitric and sulfuric acid.…”

The optical and physical properties of atmospheric aerosols over the Indian Antarctic stations during southern hemispheric summer of the International Polar Year 2007–2008

“…Even a small quantity of absorbing aerosols (anthropogenic or natural) over the highly reflecting snow might enhance the warming of the atmosphere (Chylek and Coakley, 1974;Randles et al, 2004) and the deposition of these particles over the surface of the snow or ice reduces the albedo (Russell et al, 2002;Hansen and Nazarenko, 2004). As such, there is an increased interest and need to investigate the properties of Antarctic aerosols, and their spatial temporal and microphysical properties to understand their climate forcing potential (Valero et al, 1983;Herber et al, 1993;Schwartz and Andreae, 1996;Hatzianastassiou et al, 2004;IPCC, 2007).…”

“…These include atmospheric particles as well (Shaw, 1979;Tomasi et al, 2007;Weller et al, 2008;Chaubey et al, 2010). Antarctic aerosols comprise of mainly sea salt, sulphate, dust, nss sulphate, NH + 4 , NO − 3 , Methane Sulphonate Niemi et al, 2005;Virkkula et al, 2006;Tomasi et al, 2007) and a small amount of efficient absorbing aerosols like black carbon (Bodhaine, 1995;Hansen et al, 2001;Hara et al, 2008;Chaubey et al, 2010). Even a small quantity of absorbing aerosols (anthropogenic or natural) over the highly reflecting snow might enhance the warming of the atmosphere (Chylek and Coakley, 1974;Randles et al, 2004) and the deposition of these particles over the surface of the snow or ice reduces the albedo (Russell et al, 2002;Hansen and Nazarenko, 2004).…”