Support to Aviation Control Service

(Source: BIRA-IASB, CGS, DLR, KNMI)  
Volcanic eruptions may eject large amounts of ash (aerosols) and trace gases such as sulphur dioxide (SO₂) into the atmosphere. These ejecta can have considerable impact on the safety of air traffic and on human health. Ground-based monitoring is carried out at only a limited number of volcanoes: most volcanoes are not monitored on a regular basis, in particular the remotely located volcanoes. Global observations of SO2 and aerosols derived from satellite measurements in near-real-time are therefore necessary to assess possible impacts of volcanic eruptions on air traffic control.

The Support to Aviation Control Service (SACS) focuses on the timely delivery of SO2 data derived from different satellite instruments, such as SCIAMACHY, OMI and GOME-2, and volcanic ash from the SEVIRI instrument. This will allow for monitoring the occurrence and extension of volcanic eruptions and plumes.

Together with information from other sources, data from SACS can assist official organisations -- the Volcanic Ash Advisory Centres (VAACs) -- when issuing alerts regarding volcanic activity to air traffic control and airline organisations, so as to help these to decide whether to reroute aeroplanes in case of volcanic clouds.

Note:   Emissions of SO₂ related to anthropogenic activies are part of the Air Quality Record Service.

Etna eruption visible in measured sulphur dioxide from space

SO2 distribution over the Mediterranean Sea during the active period of Mt. Etna in summer 2001. The large image is a three day composites of GOME overpasses between 22 and 24 July 2001 (see below). The inlay shows the smoke plume of Mt Etna on 23 July 2001 as seen by the high resolution sensor MODIS on board TERRA.

The eruption of Mt. Etna on 29 October 2002, as seen by the MERIS and SCIAMACHY sensors on board ENVISAT. The large MERIS image shows the smoke plume of Mt Etna, extending over the Mediterranean Sea in South-eastern direction. The inlay shows the SO2 distribution over Mediterranean Sea, as measured by the SCIAMACHY instrument. Clearly visible are the high SO2 concentrations downwind of the smoke plume.

SO2 plume from the Etna monitored by GOME

12-14 July 2001	22-24 July 2001	27-29 July 2001	31 July-2 August 2001
The series of images show the SO2 distribution over the Mediterranean Sea during the active period of Mt. Etna in summer 2001. The images are three day composites of GOME overpasses. Heavy eruptions started on 12 July and culminated between 22 July and 29 July. Highest SO2 concentrations were recorded in the Southeast of Mt. Etna, which corresponds nicely with the visible information about the extension of the volcanic plume provided by other space-borne sensors. The largest extent of the SO2 cloud was about 350.000 km2, where higher levels of sulphur dioxide were even recorded in the inner parts of the Libyan Desert. Maximum concentrations were about 5 DU (Dobson Units), which is 15 times the background concentration in the atmosphere.

SO2 plume from the Etna monitored by SEVIRI

Animated gif (2.1 MB) of volcanic ash emitted by Etna during the eruption on 22 July 2006, derived from infrared channels of the SEVIRI instrument aboard Meteosat Second Generation (a.k.a. Meteosat 8).

Further information

• General introduction to the Support to Aviation Control Service

• General background information on the Volcanic & Air Quality SO2 Services

• Highlights of SO2 emissions related to volcanic eruptions:
  • Eruption of the Grímsvötn volcano (Iceland) on 1-2 November 2004
  • Eruption of the Piton de la Fournaise volcano on Réunion Island -- March/April 2007

Jos van Geffen / Ronald van der A, last modified: April 2008