MACC is monitoring carefully the developments around the eruption of the Grimsvotn volcano on Iceland. This page provides information about the current capabilities of the pre-operational MACC global monitoring system. There is also information about available satellite observations. For formal volcanic ash plume advisories we refer to the London Volcanic Ash Advisory Centre.

Use of OMI satellite observations to provide more accurate SO2 plume forecasts

The plots above show how MACC uses satellite observations to improve sulphur dioxide plume simulations. The left plot shows the forecast from the previous day, the middle plot shows the available satellite observations of SO2 from OMI and SCIAMACHY, and the right plot shows the analysis (merge of the forecast with the observations) using the OMI observations only (indicated by the black squares). This analysis is then used for a new improved forecast as shown in the plot below, which shows the forecast valid for 25 May 2011. The system that provided the plots above is still under development and the results are therefore only indicative of the real situation.

Daily simulations of SO2 plume extent

Using basic assumptions about the injection height of sulphur dioxide by the volcano and assuming that the volcano will keep erupting at the same rate, MACC provides daily simulations of the expected plume extent for the next few days. These simulations represent SO2 only; volcanic ash has different properties and therefore is transported differently through the atmosphere.

Aerosol data assimilation and forecasts

MACC also assimilates aerosol observations from the MODIS instruments on board of the American Aqua and Terra satellites. The simulation below shows a simulation of the plume of volcanic ash starting from 21 May in terms of total ash content in the atmopsheric column. Basic assumptions about the injection height and the size distribution of the ash particles had to be made. These assumptions influence the the outcome of the simulations.

High resolution regional simulations of the ash plume

MACC uses an ensemble of high resolution regional models to monitor and forecast European air quality. The EURAD model based at the University of Koeln has produced detailed simulations of the ash plume over Europe. A full simulation can be found by clicking on the image below.

Observations

MACC does not carry out observations itself, but tries to optimally combine its modelling systems with the available observations from satellites, aircraft, and ground-based networks. Although not all available observations are assimilated in the MACC system, MACC will look at the observations that provide information on the extent of the plume over time to assess the situation retrospectively.

• EUMETSAT provides relevant products from its range of satellite instruments.
• ESA
• CALIPSO lidar observations of aerosol and clouds
• MODIS visual imagery
• SO2 data and alert service
• ULB SO2 alert based on IASI observations