New SEVIRI Volcanic Ash Discriminator
A new algorithm has been implemented based on using the SEVIRI IR channels at 6.2 µm, 7.3 µm, 8.7 µm, 11 µm and 12 µm. The algorithm determines whether there is cloud/ice using the 11 and 12 µm channels; whether there is SO2 (upper troposphere/lower stratosphere) using the 6.2 and 7.3 µm channels; and whether there is ash using the 8.7, 11 and 12 µm channels. A simple water vapour correction is applied and account is taken of the SEVIRI viewing angle. The method has been implemented for the recent Soufriere Hills, Montserrat eruption of 12 February, 2010. The animation above utilises the the full 15 minute time resolution of SEVIRI data and relies only on the IR channels so has no day/night limitation. Further tests are planned.
Acknowledgment. Paul Eckhardt implemented the code to calibrate the level 1.5 SEVIRI data.
Estimation of the emission profile is base on the FLEXPART model, more information can be found here: