Aerosol Measurements at South Pole: Climatology and Impact of Local Contamination

Abstract

The Atmospheric Research Observatory (ARO), part of the National Science Foundation's (NSF's) Amundsen-Scott South Pole Station, is located at one of the cleanest and most remote sites on earth. NOAA has been making atmospheric baseline measurements at South Pole since the mid-1970's. The pristine conditions and high elevation make the South Pole a desirable location for many types of research projects and since the early 2000's there have been multiple construction projects to accommodate both a major station renovation and additional research activities and their personnel. The larger population and increased human activity at the station, located in such close proximity to the global baseline measurements conducted at the ARO, calls into question the potential effects of local contamination of the long-term background measurements. In this work, the long-term wind and aerosol climatologies were updated and analyzed for trends. Winds blow toward the ARO from the Clean Air Sector ~88% of the time and while there is some year-to-year variability in this number, the long-term wind speed and direction measurements at South Pole have not changed appreciably in the last 35 years. Several human activity markers including station population, aircraft flights and fuel usage were used as surrogates for local aerosol emissions; peak human activity (and thus likely local emissions) occurred in the 2006 and 2007 austral summer seasons. The long-term aerosol measurements at ARO do not peak during these seasons, suggesting that the quality control procedures in place to identify and exclude continuous sources of local contamination are working and that the NSF's sector management plan for the Clean Air Sector is effective. No significant trends over time were observed in particle number concentration, aerosol light scattering coefficient, or any aerosol parameter except scattering Ångström exponent, which showed a drop of ~0.02 yr -1 over the 36-year record. The effect of discrete local contamination events in the Clean Air Sector is discussed using one well-documented example.

Three years of measurements of light-absorbing aerosols over coastal Namibia: seasonality, origin, and transport

“…The daily mean average of 53 (±55) ng m −3 is in accordance with previous observations in remote locations of the world shown in Table 1 (Bodhaine, 1995;Andreae et al, 1995;Derwent et al, 2001;von Schneidemesser et al, 2009;Marinoni et al, 2010;Sheridan et al, 2016). Andreae et al (1995) found eBC mass concentrations lower than 50 ng m −3 along a cruise transect at 19 • S over the south-east Atlantic between Brazil and Angola, except when approaching the African continent, when concentrations increased in the range 50-150 ng m −3 , indicating a strong continental influence in this otherwise pristine environment.…”

Near‐Surface Refractory Black Carbon Observations in the Atmosphere and Snow in the McMurdo Dry Valleys, Antarctica, and Potential Impacts of Foehn Winds

“…Observations of equivalent black carbon (eBC) have been collected by aethalometers deployed at the Halley Station located on the Brunt Ice Shelf in the Weddell Sea (Wolff & Cachier, 1998), on the Antarctic Peninsula (Pereira et al, 2006), at Neumayer Station on the Eefkström Ice Shelf in the Northeast Weddell Sea (Weller et al, 2013), at McMurdo Station (Hansen et al, 2001), and over several decades at the South Pole Station (Bodhaine, 1995;Hansen et al, 1988;Sheridan et al, 2016;Warren & Clarke, 1990). In general, these studies found that eBC is present on the continent at low concentration (0.3-8.3 ng/m 3 , Table 1) at their respective locations, with the exception of higher concentrations around field camps (~20 to~300 ng/m 3 at McMurdo Station, Table 1).…”

Classifying aerosol type using in situ surface spectral aerosol optical properties

“…After corrections, absorption coefficients measured by the PSAP or CLAP have an uncertainty of ∼ 20 % (Sherman et al, 2015). Finally, all data are passed through a qualityassurance-quality-control editing process in which measurement records are screened for atypical aerosol parameters (see Delene andOgren, 2002, andSheridan et al, 2016, for detailed descriptions of quality assurance and quality control procedures). Points that appear anomalous due to local pollution sources (nonrepresentative of regional aerosol), instrument error or excessive noise are not included in this analysis.…”