A Six-Year Record of Volcanic Ash Detection with Envisat MIPAS

For the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on-board ESA's Envisat a fast detection method for volcanic ash was developed that can be applied globally and for long time series. From radiance simulations with the JUelich RApid Spectral SImulation Code (JURASSIC) taking single scattering into account an ash detection threshold was derived based on two spectral windows. This threshold allows to distinguish between ice clouds and small volcanic ash particles with a scattering radius range of 0.4 - 3.1 μm. For the eruption of the Chilean Puyehue-Cordon Caulle volcano in June 2011 it is demonstrated that the detection threshold works well in practice. The analysis of MIPAS data with this new ash detection method shows that all major volcanic eruptions were detected between 2006 to 2012.