IASI

COMET has developed methods for measuring SO2 and ash release from active volcanoes using data from the Infrared Atmospheric Sounding Interferometer (IASI).

IASI observations. Credit: ESA

IASI is probably the most advanced instrument carried on the MetOp satellite.  It is providing a wealth of data to further our understanding of atmospheric processes and the interactions between atmospheric chemistry and climate.

The sophisticated IASI instrument is a Fourier Transform Spectrometer based on a Michelson Interferometer coupled to an integrated imaging system that observes and measures infrared radiation emitted from the Earth.

Infrared radiation directed into the IASI instrument. Credit: ESA

The optical interferometry process samples the atmosphere in the infrared band between wavelengths of 3.4 and 15.5 microns. This enables the instrument to establish temperature and water vapour profiles in the troposphere and the lower stratosphere, as well as measuring other compounds including SO2 and volcanic ash.

Data from the whole of the IASI instruments’ lifetimes (2007 to present) have been analysed using algorithms developed by the Earth Observation Data Group at the University of Oxford.

The web page displays volcanic SO2 plumes and has also now been updated with NRT ash flag computation. IASI data are analysed assuming different altitudes for ash (400, 600 and 800 mb) and vertical distribution for SO2 (between 0 and 20 km: 1-2 km, 4-5 km, 9-10 km, 14-15 km, 19-20 km).  All analysed data are available for download, and the data format is netcdf to allow maximum portability.

The data are available in near real time, within ~ 3 hours of the measurement being made by the instrument.

Read more on volcanic ash

Read more on SO2