[1] The eruption of the Eyjafjallajökull volcano, Iceland, in April and May 2010 caused unprecedented disruptions of European air traffic showing that timely monitoring of volcanic ash and SO 2 dispersion as well as the corresponding plume heights are important for aviation safety. This paper describes the observations of SO 2 and BrO columns in the eruption plume and the determination of the SO 2 plume height using the GOME-2 satellite instrument. During the eruptive period in May 2010, SO 2 total columns of up to $20 DU and BrO columns of $7.7 Â 10 13 molec/cm 2 were detected. The BrO/SO 2 ratio estimated from the GOME-2 observations of the Eyjafjallajökull eruption varies from 1.1 Â 10 À4 to 2.1 Â 10 À4. The SO 2 plume heights estimated from the GOME-2 observations on 5 May range from 8-13 km and mostly agree within 1-3 km with visual observations, radar data and modeling results. Furthermore, the GOME-2 SO 2 observations are compared with in situ measurements of the DLR Falcon aircraft on 17 and 18 May 2010 and with Brewer instruments at Valentia, Ireland and Hohenpeissenberg, Germany. The SO 2 columns derived from the Falcon profile measurements range from 0.6-4.7 DU and the comparison with the GOME-2 measurements shows a good agreement, mainly within 1 DU. The Brewer observations at Hohenpeissenberg also agree well with the GOME-2 measurements with a daily average SO 2 column of $1.3 DU during the overpass of the SO 2 cloud on 18 May, whereas the Brewer instrument at Valentia shows up to 50% higher SO 2 columns ($8 DU) on 11 May.Citation: Rix, M., P. Valks, N. Hao, D. Loyola, H. Schlager, H. Huntrieser, J. Flemming, U. Koehler, U. Schumann, and A. Inness (2012), Volcanic SO 2 , BrO and plume height estimations using GOME-2 satellite measurements during the eruption of

International audienceSatellite-based remote sensing measurements of volcanic sulfur dioxide provide critical information for reducing volcanic hazards. This paper describes the use of SO2 measurements from the thermal infrared sounder IASI and the UV-VIS instrument GOME-2 in services related to aviation hazard and early warning of volcanic unrest. The high sensitivity of both instruments to SO2 allows the detection and global tracking of volcanic eruption plumes and makes them a valuable tool for volcanic aviation hazard mitigation. The GOME-2 and IASI SO2 data are produced in near-real time and distributed to the Volcanic Ash Advisory Centers (VAACS) to assist them in issuing alerts to airlines and air traffic control organizations. Examples of recent eruptions affecting air traffic are presented including Jebel al Tair (Yemen, September 2007), Mount Okmok (Alaska, July 2008), and Mount Kasatochi (Alaska, August 2008). In addition, GOME-2 can detect changes in the SO2 emissions from passively degassing volcanoes and, therefore, provide critical information for hazard assessment. The monitoring of pre-eruptive degassing by GOME-2 is used in early warning of volcanic activity by a mobile volcano fast response system in combination with numerous other parameters, such as seismicity, deformation, and thermal anomalies

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Within the projects SACS (Support to Aviation Control Service) and Exupery (the mobile volcano fast response system, VFRS) S02 total columns are retrieved from different space-borne instruments such as GOME-2, SCIAMACHY and OMI. The backward trajectory matching technique is applied to relate exceptional S02 values to particular sources and volcanic regions. Additionally, the moment of the eruption as well as the emission and the plume height can be estimated. Dispersion modeling is applied to forecast the motion of the plume and to estimate the S02 emissions.

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