Support to Aviation Control Service (SACS): an online service for near real-time satellite monitoring of volcanic plumes

Brenot, H., Theys, N., Clarisse, L., van Geffen, J., van Gent, J., Van Roozendael, M., van der A, R., Hurtmans, D., Coheur, P.-F., Clerbaux, C., Valks, P., Hedelt, P., Prata, F., Rasson, O., Sievers, K. and Zehner, C.: 2014,
Nat. Hazards Earth Syst. Sci. 14, 1099-1123.


Volcanic eruptions emit plumes of ash and gases into the atmosphere, potentially at very high altitudes. Ash-rich plumes are hazardous for airplanes as ash is very abrasive and easily melts inside their engines. With more than 50 active volcanoes per year and the ever-increasing number of commercial flights, the safety of airplanes is a real concern. Satellite measurements are ideal for monitoring global volcanic activity and, in combination with atmospheric dispersion models, to track and forecast volcanic plumes. Here we present the Support to Aviation Control Service (SACS,, which is a free online service initiated by the European Space Agency (ESA) for the near-real-time (NRT) satellite monitoring of volcanic plumes of SO2 and ash. It combines data from three ultraviolet (UV)-visible and three infrared (IR) spectrometers. The UV-vis sensors are the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2) on-board the two polar orbiting meteorological satellites (MetOp-A & MetOp-B) operated by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). The IR sensors are the Atmospheric InfraRed Sounder (AIRS) and the Infrared Atmospheric Sounding Interferometer (IASI) on-board MetOp-A & MetOp-B. This new multi-sensor warning system of volcanic emissions is based on the selective detection of SO2 and ash. This system is optimised to avoid false alerts while at the same time limiting the number of notifications in case of large plumes. A successful rate with more than 95% of notifications corresponding to true volcanic activity is obtained by the SACS system.


   1. Volcanic eruptions: a threat to aviation safety
   2. Overview of SACS
   3. Description of satellite data products used by SACS
      3.1 SO2 column retrievals from UV-visible sensors
          (SCIAMACHY, OMI, GOME-2)
      3.2 SO2 index retrievals from thermal IR sensors
          (IASI and AIRS)
      3.3 Absorbing aerosol index retrievals from UV-visible sensors 
          (SCIAMACHY, OMI, GOME-2)
      3.4 Ash index retrieval from the thermal IR sensors
          (IASI, AIRS)
      3.5 Limitations of satellite products in detecting volcanic plumes
          3.5.1 SO2 products
          3.5.2 Aerosol products
          3.5.3 Known anomalies impacting the data
   4. Global monitoring of volcanic SO2 and ash emissions
      4.1 Temporal and spatial sampling
      4.2 SACS strategy for volcanic SO2 and ash notifications
          4.2.1 Criteria for SO2 and ash notifications
          4.2.2 SACS multi-sensor SO2 and ash-warning system
      4.3 10 years of data and notifications archive
          4.3.1 Notifications from 2004 to 2006 
                (SCIAMACHY, OMI and AIRS)
          4.3.2 Notifications from 2007 to 2012 
                (SCIAMACHY, OMI, AIRS, GOME-2A and IASI-A)
          4.3.3 Notifications in 2013 
                (OMI, AIRS, GOME-2A, IASI-A, GOME-2B, IASI-B)
   5. Conclusions and outlook
PDF file of the paper (24 pages; 13.1 MB)

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created: 31 October 2013
last modified: 5 June 2014