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Satellite observations confirm that Bárðarbunga-Holuhraun volcanic emissions were transported from Iceland to Finland last autumn

Satellite observations confirm that Bárðarbunga-Holuhraun volcanic emissions were transported from Iceland to Finland last autumn

Satellite instruments and ground-based devices detected high levels of atmospheric sulfur dioxide concentrations in Lapland.

On August 16, 2014 Icelandic Met Office reported increasing volcanic activity nearby the Bárðarbunga volcano. On August 31 eruption started North-East from Bárðarbunga at the Holuhraun-fissure. This so-called fissure-eruption emitted a large amount of sulfur dioxide into the atmosphere.

Sulphur dioxide (SO2) is a long-lived gas that can be transported far away from the volcanic emission source. Sulphur dioxide is toxic when present in high concentrations near the surface and it can affect air quality and human health. Since the amount of sulfur dioxide in normal situations is very low in the atmosphere, it can be used for monitoring volcanic emissions.

Elevated SO2 concentrations were observed from satellite instruments in Iceland on September 1, 2014 (red areas in the figure). During the following days, the volcanic SO2 was trasported eastward, and reached Finland on September 5. High SO2 concentrations were observed in northern Finland several times during September 2014.

In the study published by Ialongo et al. (2015), SO2 observations from OMI (Ozone Measurement Instrument) onboard NASA's EOS-Aura satellite as well as OMPS (Ozone Mapping and Profiler Suite) on-board Suomi-NPP satellite were used. The operational SO2 products are available globally, and typically within a few hours after the satellite overpass. In addition, OMI and OMPS sulfur dioxide observations are received from the international satellite-service station in Sodankylä. These SO2 retrievals cover Northern Europe and are distributed via Sampo-service ( about 15 minutes after the measurements are performed.

Ground-based measurements and satellite observations confirm that the volcanic SO2 was transported close to the surface.

Elevated SO2 concentrations were observed from Brewer measurements performed in Sodankylä, which is located more than 2000 km from the Bárðarbunga volcano in Iceland. The SO2 observations from Brewer agree within the errorbars with the satellite observations. Satellite-based SO2 values depend on the height of the SO2 cloud. In this case, the best agreement with the ground-based retrievals is obtained when a SO2 cloud height of 0.9 km is assumed in the satellite retrieval algorithm. This means that the volcanic SO2 was probably located close to the surface. This is confirmed by the fact that elevated levels of SO2 concentrations were also observed at several air quality stations in northern Finland during the same days when the satellite and Brewer instruments measured high concentrations of sulfur dioxide. This is the first time when satellite observations of volcanic SO2-plume located very close to the surface were compared with ground-based data, including air quality measurements.

OMI SO2 maps during the Holuhraun eruption in September 2014. The dates (day/month) are indicated in the title of each panel. The blue crosses indicate the location of Sodankylä. Red areas correspond to elevated SO2 levels.

Additional Information:

Postdoc researcher Iolanda Ialongo,
Reference: Ialongo, I., Hakkarainen, J., Kivi, R., Anttila, P., Krotkov, N.A., Yang, K., Li, C., Tukiainen, S., Hassinen, S., and Tamminen, J.: Comparison of SO2 operational satellite products with ground-based observations in northern Finland during the Icelandic Holuhraun fissure eruption, Atmos. Meas. Tech., 8, 2279-2289, doi: 10.5194 / amt-8-2279-2015, 2015.


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