Eruption of the Grímsvötn volcano on Iceland November 2004

[Image: Matthew J. Roberts]

 
Late in the evening of Monday 1 November 2004 the Grímsvötn volcano on Iceland erupted spectacularly. The volcano, which is located under the Vatnajökull ice cap, ejected masses of ash and gases high into the atmosphere, up to 12 km. This forced some airlines to divert their flights, in order to avoid flying through the ash cloud. Ash from the eruption has landed in Norway, Sweden and Finland, the BBC reported.

The eruption also released some sulphur dioxide (SO₂) into the atmosphere, and this was measured by the SCIAMACHY instrument. Early 2005, when the SO₂ data service was started with some preliminary test and maps, the SCIAMACHY data showed SO₂ first north of Iceland and then travelling across Europe.

In the initial setup of the service, the SO₂ slant column value was used for alerts of SO₂ events, and the SO₂ detected on 2 Nov. 2004 satisfied those criteria, but only just.

Since that time, the SO₂ data service has been reconstructed and improved on several points: improved background corrections to minimisize false SO₂ detections, the use of total SO₂ column (instead of the slant column), etc. With these changes, the SO₂ values on 2 Nov. 2004 are just below the alert criteria.

The data sets found in the current (version 1.1) SO₂ data archive are furthermore based on reprocessed SCIAMACHY measurement data, and with this new input data sets some SCIAMACHY orbits are unfortunately missing from the data archive -- no idea why -- and this is also the case for the orbit with the SO₂ peak just north of Iceland seen first on 02 Nov. 2004, as can be see on this page in the data archive: the orbit crossing Iceland is not there.

This makes it unfortunately impossible to recreate the SO₂ maps in the new format, with the current colour scale. Our sincere apologies for this!

Still, the event showed an interesting motion of the SO₂ across Europe, and therefore we decided to give here access to the old web pages describing the event, where "old" means based on a previous version of the data and using the previous colour bar for the maps.