SO2 data and alert service
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Eruption of the Grímsvötn
volcano on Iceland
November 2004Motion of volcanic SO2 across Europe ?
[Image: Matthew J. Roberts]
NOTE: see the main page on this event for some important remarks regarding the SO2 processing and the maps presented on these pages.
As mentioned on the main page about the eruption of the Grímsvötn volcano, the air from above the volcano moves first to the Northeast, then bends to Norway and further Southeast. The following pictures show the SO2 concentration above Europe for some days around the eruption. The location of the Grímsvötn volcano is indicated by a triangle.These pictures show that there may indeed be a cloud of SO2 moving. Further analysis of the data will have to done to make sure that no artifacts or background noise is spoiling the data. The interpretation given below the pictures is therefore preliminary.
Notes:
- SCIAMACHY scans the Earth from North to South and the orbits are performed from East to West, with a difference of about 100 minutes between two successive orbits. Each orbit is subdivided in several nadir states. Below each picture the measurement time of one of the nadir states is given.
- Measurements up to 85 degrees Solar Zenith Angle (SZA) are shown. At high SZA, above 80 degrees (for the days shown: above roughly 65 North), the results usually have to be treated with care, as the retrieval of data from these measurements is rather difficult.
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SO2 slant column data of more than one day before the eruption above
Europe. There are a few SCIAMACHY ground pixels that show a clear SO2
concentration, but these are very scattered and all measured at SZA
above 80 degrees.
The times plotted in this and the following graphs mark the end of a nadir state in UTC. |
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SO2 slant column data of several hours before the eruption. There
are several SCIAMACHY ground pixels that show a clear SO2 concentration
in some patches North of Iceland. Perhaps these patches are related
to SO2 emissions during the earthquakes that preceeded the eruption (as
mentioned on the main page regarding this
eruption), but they could also be due to artifacts in the data.
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SO2 slant column data of several hours after the start of the eruption.
North of Iceland is a large patch of large SO2 concentrations, and this
is most likely due to SO2 emissions during the eruption. If SO2 was
released before the eruption (previous image), then this seems to have
moved very little.
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SO2 slant column data of a day and a half after the start of the eruption.
The patch with large SO2 concentrations North of Iceland on 2 November
(previous image) has moved just across the Finnish border into
Northwest Russia. This motion agrees more or less with the
motion of the air shown on the main page
regarding this eruption.
The area in Northwest Russia, around the town Arkhangelsk, is known for its heavy industry, so the SO2 could be (in part) due to pollution. The nadir state to the south shows some SO2 on its east side; this could be related to volcanic and/or anthropogenic SO2 coming from the north. The large SO2 concentrations above central Ukraine are probably due to pollution: this patch does not appear in the other pictures, indicating that the SO2 has rained out very quickly (which is the case for SO2 at low altitudes). |
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SO2 slant column data of two and a half days after the start of the eruption.
The patch with large SO2 concentrations above Northwest Russia on 3 November
(previous image) has moved to Central Russia. This motion more or less
agrees with the motion of the air shown on
the main page regarding this eruption.
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SO2 slant column data three and a half days after the eruption.
The patch with large SO2 concentrations above Central Russia on 4 November
(previous image) seems to have moved to the South, to between the Black
Sea and the Caspian Sea, more or less in agreement with the
motion of the air shown on the main page
regarding this eruption. Meanwhile, the Northern parts of Europe now
seem to be free of SO2. West of the Black Sea, over Albania, an SO2 patch
is visible -- it is unclear where this comes from.
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SO2 slant column data four and a half days after the eruption.
The motion of the air shown on the main
page regarding this eruption suggests that some of that air between
the Black and Caspian Seas (previous image) moves to above the
Caspian Sea. The SO2 concentration there are somewhat above the
background, but only very weekly and hence it is uncertain whether this
has anything to do with SO2 from the volcano eruption.
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SO2 slant column data five and half days after the eruption.
The SO2 above the Caspian Sea in the previous image has either
dissolved or perhaps moved a little to the east; due to the poor
global coverage of SCIAMACHY it is difficult to decide what happened.
The SO2 concentration shows only a little above the
background, but only very weekly and hence it is uncertain whether this
has anything to do with SO2 from the volcano eruption.
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View and animated GIF from 30 Oct. up to 08 Nov.: |
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NOTE: The images at this page were made in January 2008, after a new background correction was implemented (to decrease the large number of artifacts at high SZA) and the captions have been adapted accordingly. With this new background correction, the motion of the SO2 across Europe seems to be more clearly visible. For reference the old page is still available.
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