A multi-sensor analysis of the 2009 eruption of Sarychev Peak, Kuril Islands: A case study for hazards to aviation

The eruption of Sarychev Peak Volcano (48°N,153°E), Kuril Islands, occurred between June 12 and 18 2009 emplacing large volumes of sulphur dioxide and volcanic ash into the atmosphere and severely disrupting air traffic in the region. The eruption was observed by several satellite-borne sensors, including the Ozone Monitoring Instrument (OMI), the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS). This work uses these three sensors concurrently, as the use of several instruments provides more frequent datasets enabling improvements in accurately locating volcanic clouds and the subsequent validation of dispersion models. The North Pacific region sees a large amount of air traffic and the clouds from Sarychev Peak intersected many major air routes. Volcanic ash poses a threat to the operation of aircraft by abrading the engines which can result in failure, as well as “sand blasting” of the cockpit windows. It is also important to detect and map any sulphur dioxide clouds created, as this can also be hazardous for aircraft. Volcanic aerosol can cause corrosion on the aircraft exterior and sulphur based minerals may be deposited within the engines, blocking cooling holes over time. SO2 can also enter the aircraft cabin through the ventilation system, which can cause respiratory problems for the passengers and crew. In addition, SO2 is often associated with volcanic ash as the two species are frequently collocated. When ash retrievals are limited by high concentrations of water vapour and ice in the atmosphere, the presence of SO2 can be used to infer the location of a potential ash cloud, so that aircraft encounters may be avoided. A collection of images from the three sensors, ranging from June 10 to 24 were acquired to determine the mass and location of the SO2 cloud. This data, along with ash cloud data collected from the two MODIS sensors for dates between June 11 and 20, was then used to create a chronology of images demonstrating the potential risk the volcanic ash and SO2 posed to the air routes in the region. Initial results suggest that the SO2 and ash clouds appeared to co-exist for the duration of the eruption, with the SO2 cloud spreading much further into Russia and over the Pacific Ocean towards North America as the clouds dispersed from June 18 onwards.. Air routes to the north-east of Sarychev Peak appear to be unaffected during the period June 12 and 15 when the cloud spread south-east over the Pacific. A much larger emission was detected on June 15 and 16, which formed a bow shaped cloud of SO2 and ash and spread laterally both east and west from the volcano, blocking passage to all air routes in the region. The clouds in this region persisted for several days until the end of the eruption when they are seen to disperse and decrease in mass. By around the 20th June, no more ash and column amounts of SO2 less than 0.2 g m -2 were detected intersecting any of the regional air routes.