Influence of local and regional air pollution on atmospheric measurements in Ny-Ålesund

Abstract

The Zeppelin observatory is a research station near the village Ny-Ålesund in Svalbard. The facility delivers data to international projects devoted to high data quality monitoring of the background air pollution in the Arctic. An approach for quantifying the influence of local and regional pollution on measurements that may be misinterpreted as long-range transported one, is presented here.The hourly gas and aerosol data measured in Ny-Ålesund and at the Zeppelin station, respectively, have been analysed along with the meteorological data from Ny-Ålesund, Zeppelin station and Longyearbyen (south-east of Ny-Ålesund).Seasonal fluctuation of the average measured values of SO 2 and NO x has been observed. Three main wind directions coincided with the peak concentration of SO 2 and NO x . The NW-N flow may bring local pollution from ship traffic and diesel power plant as well as biogenic SO 2 from the oxidation of DMS. The monthly average number of particles with diameter characteristic for ship plume (50-100 nm), was elevated for the hours when ships have been registered in the local call list. The number concentration of particles with diameter 200 nm, typical for Arctic haze events, and concentration of non-sea salt sulphate rise during springtime. The FLEXTRA-trajectory analysis indicated that most pollution brought by E-SE and SW flows may be of long-range and/or regional origin. Events with these flow directions need to be interpreted with caution.

Effect of seasonal mesoscale and microscale meteorological conditions in Ny-Ålesund on results of monitoring of long-range transported pollution

“…Firstly, long-range transported pollution prevailing in the Arctic in winter and spring decreases in summer because of the change in the position of the Arctic Front, which prevents effective south-to-north longrange air transport (AMAP 2006). Secondly, there are few local anthropogenic sources of air pollution in the Artic and some of them have intermittent emission rates, e.g., ship traffic (Dekhtyareva et al 2016). Thirdly, the conversion rate of SO 2 to SO 4 2increases in summer, a process governed by two major mechanisms.…”

“…This institute also provided hourly temperature, pressure, relative humidity, wind speed and wind direction data obtained at the two stations. Previous studies have shown that the local wind measurements at the Zeppelin station are subject to a wind-shielding effect from nearby mountains, so these data cannot be used for comparison with measurement results from Ny-Ålesund (Dekhtyareva et al 2016). Therefore, atmospheric stratification and local wind flows in the lowest atmosphere (0-500 m height) were studied using atmospheric radiosoundings performed by the Alfred Wegener Institute in Ny-Ålesund.…”

“…Data and knowledge exchange between researchers from 12 different nations leads to joint publications and improves our scientific understanding of various processes in a rapidly changing Arctic (Norwegian Polar Institute 2016). Specific attention is given to the study of the Arctic haze phenomena, aerosol of anthropogenic origin enriched in non-sea salt sulphate (XSO 4 2-) and transported over long distances from mid-latitudes to the Arctic during winter and spring (Quinn et al 2007;Dekhtyareva et al 2016;Ferrero et al 2016). Ny-Ålesund is situated far from major industrial areas, and is therefore considered suitable for monitoring of long-range transported pollution.…”

“…Long-range transported pollution is dominant during all seasons of the year except summer, when instead ship traffic has been shown to be a significant local source of pollution (Eckhardt et al 2013;Dekhtyareva et al 2016). In summer, the mixing height of the ABL may increase, especially due to radiative heating of the surface leading to convection, and therefore local pollution may be transported aloft (Stull 1988).…”

“…Subsidence inversions may occur in the Arctic troposphere in summer as a response to diabatic heating and convection over land masses in the sub-Arctic (50°-55°N) after the springtime snowmelt (Matsumura et al 2014). Another source of local pollution in Ny-Ålesund is the small power plant running on low-sulphur diesel year-round (Dekhtyareva et al 2016). In order to prevent interference of local pollution in the monitoring of background air composition, the Zeppelin Observatory was established 2 km away from the settlement, on the top of Mount Zeppelin at 474 m a.s.l.…”