GOME-2/MetOp-A » Volcanic Sulfur Dioxide (SO2)

Sulphur dioxide (SO2) is emitted into the atmosphere not only by volcanic eruptions, but also by anthropogenic activity such as the combustion of fossil fuels. In some regions it contributes significantly to air quality issues. Sulphur dioxide acts as an acid. Inhalation results in laboured breathing, coughing, sore throat and may cause permanent pulmonary damage. It further plays an important role in climate change, if it finds itself in high atmospheric regions by volcanic eruptions, where it can lead to temporary cooling. It is furthermore hazardous to aviation causing sulphidation in the engines or, in form of acid rain, it increases the oxidation of aircraft components.
SO2 emissions are a good indicator for volcanic activity, since besides weak anthropogenic emissions there are no other known sources for atmospheric SO2. Furthermore it was found that for some volcanic eruptions SO2 can be a good proxy for the much harder to detect volcanic ash. Volcanic ash can be hazardous not only for the local population but also for aviation since it can cause total engine failure if it melts and then congeals in the engine. Furthermore ash is highly abrasive to engine turbine vanes and propellers.

The operational processing and routine analysis of GOME-2 SO2 data are based on the differential optical absorption spectroscopy (DOAS) method in the UV wavelength range around 320 nm. More details can be found on the product page

GOME-2 is an ultraviolet spectrometer (290-790 nm) aboard the polar-orbiting satellites MetOp-A (launched in 2006) and MetOp-B (launched in 2012) which takes global measurements of atmospheric composition on a daily basis. GOME-2 provides nadir-view scans with a ground pixel resolution of 40 x 40 km2 (MetOp-A) and 80 x 40 km2 (MetOp-B).
Under the leadership of IMF, DLR-EOC provides operational trace gas measurements, including total SO2 columns, in near-real-time (i.e., within 2 hours of recording) in the framework of EUMETSAT's Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M-SAF).

The operational GOME-2/MetOp sulfur dioxide products are being used in a number of services including volcano monitoring:

Today's SO2 measurements

Latest volcanic SO2 detection

Pavlov Eruption, March 2016

In the evening of March 27th, 2016 the Aleutian stratovolcano Pavlov erupted with strong ash clouds rising up to 10km. The alert status was set to red. GOME-2 is observing the SO2 plume and measured a maximum total vertical SO2 column of 18 DU.

Animation of GOME-2 SO2 measurements beginning 28/03/2016

Animation of daily SO2 measurements of the SO2 plume from the erutpion of Pavlov starting on 28/03/2016.
Data from GOME-2 aboard MetOp-A&-B is regridded on a common 0.1dg x 0.1dg grid (~11km x 11km). Only data with a solar zenith angle <75 dg is used.

Etna Eruption, December 2015

In the morning of December 3rd, 2015 a series of volcanic eruptions started at the 'Voragine' crater of the Etna on Sicily (Italy). This type of eruptions is called paroxysmal eruption or paroxysm, which is a synonym for increasing volcanic activity. Paroxysms are characterized by frequent explosions, becoming more and more intense until they come to an end in a final violent eruption.
After the first paroxysm on Dec 3rd, a second and third climax occurred in the morning (9-10h UTC) and evening of the following day (20:30h-21:15h UTC). A fourth paroxysm occurred in the afternoon of Dec 5th. During the eruptions, which are considered as the strongest of the last 20 years, large amounts of ash and sulfur dioxide (SO2) were emitted into the atmosphere. The SO2 emissions are clearly detectable by the GOME-2 instruments on the MetOp-A & -B satellites and have a total vertical SO2 column of more than 20 DU (see animation of daily measurements)
The GOME-2 measurements show that the SO2 plume from the first paroxysm was transported eastwards and is even detectable over Japan and the Pacific Ocean five days after the event. The SO2 plume of the second eruption in the morning of Dec. 4th was transported south-east, east, whereas the SO2 plume from the afternoon eruption was transported south-west. The two plumes from the Dec. 5th/6th paroxysms were transported northwards. They arrived over southern Germany in the evening of Dec. 7th and morning of Dec. 8th , respectively, where they got detected in-situ at the meteorological institute Schneefernerhaus on the Zugspitz-Mountain.
Based on a new algorithm developed at DLR IMF, the SO2 plume height of the current eruption of Etna retrieved from GOME-2 data is in the range from 8 to 10km (see animation of plume height retrieval results), which is in agreement with satellite images of the ash cloud from MODIS (NASA/TERA&AQUA) and with measurements of SEVIRI (MSG) and CALIOP (NASA/CALYPSO) - many thanks to N. Theys (BIRA); E. Carboni, (University Oxford) and L. Clarisse (Free University Brussels) for this information.

Animation of GOME-2 SO2 measurements from 03/12/2015 to 08/12/2015

Animation of retrieved SO2 plume heights from 03/12/2015 to 07/12/2015

Animation of daily SO2 measurements from the paroxymal erutpion of Etna from 03/12/2015 to 08/12/2015.
Data from GOME-2 aboard MetOp-A&-B is regridded on a common 0.1dg x 0.1dg grid (~11km x 11km). Only data with a solar zenith angle <75 dg is used.
Animation of retrieved SO2 plume heights from 03/12/2015 to 07/12/2015.

Wolf Eruption, May 2015

Last update: 26/05/2015

On 25 May 2015 the Wolf Volcano situated on Isabela Island, which is part of the Galapagos Islands, erupted after 33 years of inactivity. Since the volcano is not located near a populated area there is no risk for the local population. The SO2 emissions are detectable with GOME-2 aboard the MetOp-A and -B.

NOTE: Daily images from 25/05/2015 - 31/06/2015 can be accessed via
where YYYYMMDD starts at 20150525.

Animation from 25/05/2015 - 31/06/2015

Animation of daily SO2 measurements over Galapagos Islands from 25/05/2015 - 31/06/2015.
Data from GOME-2 aboard MetOp-A&-B is regridded on a common 0.1dg x 0.1dg grid (~11km x 11km). Only data with a solar zenith angle <75 dg is used.

Calbuco Eruption, April 2015

Last update: 24/04/2015

On 22 April 2015 the Calbuco Volcano in Chile erupted after 42 years of inactivity with strong emissions of ash and SO2. From 23 April until mid-May GOME-2 aboard the MetOp-A and -B satellites detected a strong SO2 cloud with a total vertical column of more than 40 DU (assuming a 15km plume height) moving north-east over the Atlantic Ocean even reaching Australia.

NOTE: Daily images from 23/04/2015 - 20/05/2015 can be accessed via
where YYYYMMDD starts at 20150423.

Animation from 23/04/2015 - 20/05/2015

Animation of daily SO2 measurements over South America from 23/04/2015 - 20/05/2015.
Data from GOME-2 aboard MetOp-A&-B is regridded on a common 0.1dg x 0.1dg grid (~11km x 11km). Only data with a solar zenith angle <75 dg is used.

Fogo Eruption, November 2014

Last update: 18/12/2014

On the morning of 23 November 2014 the Pico do Fogo volcano on Cape Verde erupted after seismic activity beginning the day before. Pico do Fogo is an active stratovolcano. The current eruption is already stronger than the last one in 1995 and currently shows emission of volcanic ash and sulphur dioxide (SO2). On 24 September GOME-2 aboard the MetOp-A and -B satellites detected a strong SO2 cloud over Cape Verde with a total vertical column of about 21 DU (assuming a 15km plume height), moving eastwards over West-Africa. The SO2 emission was detectable with GOME-2 until 09 December 2014.
The eruption caused a shut-down of air space over Cape Verde and Lava streams destroyed the village Portelo.

NOTE: Daily images from 24/11 - 09/12/2014 can be accessed via
where YYYYMMDD starts at 20141124.

Animation from 24/11/2014 - 09/12/2014

Animation of SO2 measurements over Cape Verde from 24/11/2014 - 09/12/2014.
Data from GOME-2 aboard MetOp-A&-B is regridded on a common 0.1dg x 0.1dg grid (~11km x 11km). Only data with a solar zenith angle <75 dg is used.

Bardarbunga Eruption, September 2014

Last update: 28/11/2014

After increased seismic activity in the past weeks, the Icelandic stratovolcano Bardarbunga erupted on 1 September 2014. The GOME-2 instruments aboard the MetOp-A and -B satellites detect a continuous emission of sulphur-dioxide (SO2) with a plume first spreading over Greenland. After 2 September the SO2 plume was transported eastwards, even over central Russia. On 5 and 6 September a second SO2 plume was transported to the south-west over Ireland (see animation below). The animation is automatically updated on a daily basis in the afternoon. On 22 September an SO2 cloud was even transported over Germany and could be detected at the meteorological institutes at Schneefernerhaus and Hohenpeissenberg. See the GOME-2 SO2 measurement here

Bardarbunga still shows an effusive type of eruption with currently no volcanic ash emission being detected. Nevertheless the volcano remains active, and an explosive eruption is still possible, which will probably produce large amounts of volcanic ash and could affect the air traffic over Europe.

NOTE: Daily images from 01/09 - 30/11/2014 can be accessed via
where YYYYMMDD starts at 20140901.

Animation from 01/09/2014 - 31/10/2014

Animation of SO2 measurements above Europe from 01/09/2014 - 31/10/2014.
Data from GOME-2 aboard MetOp-A&-B is regridded on a common 0.1dg x 0.1dg grid (~11km x 11km). Only data with a solar zenith angle <75 dg is used.

Grimsvoetn Eruption, May 2011

Sulfur dioxide (SO2) is an excellent indicator for volcanic activity.Satellite observations of volcanic SO2 are used for aviation safety and early warning of volcanic activity. The SO2 retrieval for the GOME-2 satellite instrument is performed in near-real time at DLR Oberpfaffenhofen at the Remote Sensing Technology Institute (IMF) and German Remote Sensing Data Center (DFD) allowing the data to be distributed to users less than 2 hours after the measurements. An SO2 plume from the recent eruption of Grímsvötn volcano, Iceland, was detected by GOME-2 on 22 May 2011. The volcanic cloud has lead to a partial airspace closure in Scotland, Ireland and northern Europe.
On the evening of 21 May 2011 an eruption occurred at Grímsvötn, Iceland. The Grímsvötn is Iceland's most active volcano, it had been dormant since the last eruption, which occurred in 2004. The volcanic eruption on Saturday evening ejected a large ash and SO2 cloud into the atmosphere, bringing into mind the eruption of Eyjafjallajökull in April 2010, which resulted in an almost complete closure of the European airspace for several days. Even though the current Grímsvötn eruption is larger than the Eyjafjallajökull eruption, it is unlikely that it will have the a comparable influence of the air traffic. First estimates of the eruption height range from 12 -17 km, which is above the typical cruising altitude of airplanes. In addition the volcanic cloud has been distributed mainly towards the north and northeast on the first two days after the eruption, leaving Europe unaffected. However, on 24 May the plume was distributed towards Scotland and lead to a partial closure of the airspace. As the forecasts indicated, the plume reached northern Germany on the evening of 24 May and lead to disruptions in air traffic.
A large sulfur dioxide (SO2) plume from the Grímsvötn eruption was detected by the atmospheric sensor GOME-2 (Global Ozone Monitoring Experiment) on the EUMETSAT satellite, MetOp-A, on the morning of 22 May. The plume was located mainly over Iceland on that day, the following day it had spread out towards the northeast (Fig. 1). On 24 May part of the plume was distributed towards the southeast and was located over Scotland at the time of the GOME-2 observation (Fig. 2), where it caused disruptions in air traffic. The eruption emitted high SO2 amounts into the atmosphere. The maximum values measured by GOME-2 are ~ 85 DU (The amount of sulfur dioxide is measured in Dobson Units (DU), the number of molecules in a square centimeter of the atmosphere). First estimates for the total erupted mass of SO2 indicate almost 1.0 x 106 tons of SO2.



Eyjafjallajoekull Eruption, May 2010

With the eruption of the Eyjafjallajoekull volcano on Iceland large amount of ash and gases such as water vapour and sulphur dioxide have been emitted into the atmosphere. Carried by winds high up in the atmosphere, the volcanic ash cloud first led to the closure of airports throughout the UK and Scandinavia, and later in the rest of northern and Western Europe. The volcano erupted, for the first time since 1821, on 20 March and started erupting for a second time on 14 April 2010. The volcano, under the glacier ice, has caused ice melt and subsequent flooding and damage locally.
Apart from the emission of ash and water vapour, the eruption of Eyjafjallajökull emitted sulphur dioxide (SO2), a colourless and toxic trace gas, into the atmosphere. The SO2 was measured since April 15, 2010, by the atmospheric sensor GOME-2 (Global Ozone Monitoring Experiment) on the EUMETSAT satellite, MetOp-A.

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