Introduction
The main advantage of satellite data is their broad spatial and temporal coverage which enables the detection of severe weather events prior to other sources. Observing volcanic ash clouds, it might seem obvious that the closer you get, the better your chance to detect them.
Therefore polar orbiting weather satellites like MetOp seem to be beneficial, since they offer excellent spatial coverage as a result of their lower flight level (820 km).
As a further consequence of the lower flight level, polar orbiting satellites like MetOp can only provide a restricted number of images per day. Therefore at lower latitudes constant monitoring of weather conditions or ash clouds is not possible. For operational weather forecasting it is essential to monitor the ever changing weather conditions.
Therefore MSG images which operate on a high temporal resolution will be preferred. The core instrument on Meteosat 9 is SEVIRI (Spinning Enhanced Visible and Infrared Imager) and provides the information of 12 different spectral bands.
One way to deal with these different images is to compare them and filter information. Apparently this task demands a lot of time and can be very challenging.
Here is an animation of the single satellite imageries for 15 April 2010 1200UTC. Navigate though the different channels and try to identify the Ash Cloud.
Figure 3.1: Different channels of Meteosat 9 for 15 April 2010 1200UTC