For the latest near real-time imagery of the continuing Eyjafjallajökull volcano eruption, please click here.

During a volcanic eruption, large amounts of ash and trace gases, especially sulphur dioxide (SO2), are injected into the higher atmosphere in unusually high concentrations.
EUMETSAT’s Meteosat and Metop satellites are good at observing volcanic ash plumes and related phenomena and are therefore essential for the monitoring and prediction of the plume characteristics. Satellite-based detection is based on observations in the ultraviolet, visible and infrared spectral bands.

Volcanic Ash Flag, 15-19 April 2010

EUMETSAT’s geostationary Second Generation Meteosats are the only satellites in orbit that can be used to derive real-time imagery of the movement of volcanic cloud over Europe. Another product based on Meteosat observations, is the so-called Volcanic Ash Flag (see image on the left). It is derived by the NWC-SAF software package and distinguishes volcanic ash from clouds by applying threshold tests using the different spectral absorption of ice clouds, water clouds and ash aerosol. The loops show observations during the past few days until now.

Source: Software by Satellite Application Facility (SAF) on Support to Nowcasting and Very Short Range Forecasting.

Other EUMETSAT instruments are more suitable to detect the remaining thin ash layer. The GOME-2 instrument on the Metop-A polar-orbiting satellite can be used to derive the track of the volcano plume in two different ways.  The broad-band absorption of ultraviolet radiation by the volcanic ash is used to produce the absorbing aerosol index (AAI) product. Sulphur Dioxide (SO2) can be measured using the specific absorption features of this gas in the ultraviolet spectral region. Both methods show the volcano plume during Metop overpasses, once per day. First results indicate that the amount of SO2 released by the Eyjafjallajökull eruption is considerably smaller than for other volcanic eruptions of the same size.
Volcanic ash and SO2 can also be detected in a completely different spectral region. Measurements by the high-resolution infrared spectrometer (IASI) on Metop-A are sensitive to both SO2 and ash aerosol.

Metop-A/GOME-2 AAI (15-18 April 2010) Source: O3M-SAF/KNMI Regularly updated data from the O3M-SAF/KNMI can be found on this web-page.	Metop-A/GOME-2 SO2 (15-18 April 2010) Source: O3M-SAF/DLR Regularly updated data from the O3M-SAF/DLR can be found on this web-page.	Metop-A/IASI SO2 (15-19 April 2010) Source: CAF

Metop-A/IASI Ash (14-19 April 2010)

Further detailed analysis of the ash plume is provided by Latmos/ULB-CNRS as shown on the left.

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