Local anthropogenic impact on particulate elemental carbon concentrations at Summit, Greenland

Abstract

Abstract. Summit, Greenland is a remote Arctic research station allowing for field measurements at the highest point of the Greenland Ice Sheet. Due to the current reliance on diesel generators for electricity at Summit, unavoidable local emissions are a potential contamination threat to the measurement of combustion-related species in the air and snow. The effect of fossil-fuel combustion on particulate elemental carbon (EC) is assessed by a combination of ambient measurements (∼1 km from the main camp), a series of snow pits, and Gaussian plume modeling. Ambient measurements indicate that the air directly downwind of the research station generators experiences particulate absorption coefficient (closely related to EC) values that are up to a factor of 200 higher than the summer 2006 non-camp-impacted ambient average. Local anthropogenic influence on snow EC content is also evident. The average EC concentration in 1-m snow pits in the "clean air" sector of Summit Camp are a factor of 1.8-2.4 higher than in snow pits located 10 km and 20 km to the north ("downwind") and south ("upwind") of the research site. Gaussian plume modeling performed using meteorological data from years 2003-2006 suggests a strong angular dependence of anthropogenic impact, with highest risk to the northwest of Summit Camp and lowest to the southeast. Along a transect to the southeast (5 degree angle bin), the modeled frequency of significant camp contribution to atmospheric EC (i.e. camp-produced EC>summer 2006 average Correspondence to: G. S. W. Hagler (gayle.hagler@gatech.edu) EC) at a distance of 0.5 km, 10 km, and 20 km is 1%, 0.2%, and 0.05%, respectively. According to both the snow pit and model results, a distance exceeding 10 km towards the southeast is expected to minimize risk of contamination. These results also suggest that other remote Arctic monitoring stations powered by local fuel combustion may need to account for local air and snow contamination in field sampling design and data interpretation.

Haze episodes at Syowa Station, coastal Antarctica: Where did they come from?

“…Furthermore, the nearest station (Molodezhnaya, 67.41°S 45.51°E) is located approximately 400 km distant from Syowa Station. According to Hagler et al [2008], the atmospheric BC concentration decreased rapidly to <1 ng m −3 in the first 30 km from BC sources in the polar region. Consequently, the anthropogenic impact from the other stations was too small to make a meaningful contribution to the haze event at Syowa.…”

Analysis of nitrate in the snow and atmosphere at Summit, Greenland: Chemistry and transport

“…The generator, however, is always operating. Prior work has shown that elemental carbon (EC) from camp activities causes concentrations 1.8–2.4 times higher at 1 km than 10 or 20 km from camp [ Hagler et al ., ]. While this study focused on EC as a tracer of local emissions, it raises the expectation of similar results for other atmospheric species.…”

Bromide and other ions in the snow, firn air, and atmospheric boundary layer at Summit during GSHOX

“…Winds at Summit are not consistently steady in speed or direction, but the least frequent direction is from due north, so all atmospheric sampling has been on the southern, "upwind" side of camp. Hagler et al (2008) pointed out that, on average, during the summers of 2003 through 2006, winds arriving at the satellite camp location passed through a northern, potentially polluted, sector (defined by point sources of pollution in the camp as well as areas where heavy equipment often was operating), 19% of the time. These authors recommended use of sector control to interrupt sampling, particularly for experiments that integrated over long periods (days or longer).…”

“…It should be noted that the "bad air" sector is defined conservatively, to account for mobile sources that are not always present (e.g., equipment grooming the runway or moving snow). Hagler et al (2008) observed that during summer 2006 the winds were out of the defined camp sector 21% of the time, but local pollution (identified by very large enhancements in aerosol absorption monitored continuously) impacted the satellite camp just 7.6% of the time…”