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20 2. Remote Sensing with MODIS
Figure 2.4 – The ash plume resulting from the Eyjafjallajokull eruption, monitored by
two sensors on April 17, 2010 (Left) Image acquired by NASA’s Aqua MODIS on April 17,
2010 showing a diffuse cloud of volcanic ash and a column plume rising at higher altitudes
(Right) Image from CNES/NASA CALIOP, lidar instrument aboard CALIPSO dedicated
to the study of the atmosphere vertical profile of aerosol.
2.2.4.1 The Eyjafjallajökull
Around 20 Mars 2010, Eyjafjallajökull, a volcano located in the south of Iceland began
its first erupting phase. A more explosive phase started on 14 april 2010. The volcano being
located beneath glacial ice, the melting water flowing back in the volcano vent resulted in
the formation of silica particules and ash, explosively rejected in the atmosphere at heights
reaching 10 km. In addition, the south-easterly path of the Jet Stream, unusually stable
at that specific period, progressively dispersed the ash plume across Europe’s airspace. Although
not specifically quantified by manufacturers, the sensitivity of aircraft engines to
ash particules, forced the Federal Aviation Administration (FAA) to shut down air-traffic
in most european countries. The financial losses caused by airspace closure to the airline
industry were estimated approximatively at 150 ME per day from 15 to 23 April. The
quantity of rejected ash and the trajectory of the resulting plumes were eventually monitored
with numerous satellite-based instruments including CALIPSO, VEGETATION
and MODIS (figure 2.4). As the eruptive phase of the volcano persisted, satellite images
of the ash cloud were used to determine its trajectory and establish low-risk air corridors.
2.2.4.2 Deepwater Horizon oil spill
In April 20, 2010, an offshore drilling platform, Deepwater Horizon, located southeast
of the Louisiana coast exploded and sank in the ocean. The explosion was followed by the
release of 8500 m 3 of crude oil per day and is considered today as the largest oil spill in the
history of petroleum industry. Data collected from several spatial instruments were used
to analyse the extend of the oil spill, and evaluate its spreading evolution with respect
to wind direction. The reflection of sun light off the ocean surface (sun glint) highlights