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Temporal and spatial structure of a volcanic ash cloud: ground-based remote sensing and numerical modeling

The Eyjafjallajökull volcano eruptions during mid April 2010 influenced European air traffic basically. This was mainly due to the low melting point of ejected material and the sharp-edged form of particles. As there is the necessity to understand the dispersion of such an ash cloud we assess the existing measurement networks and evaluate the existing numerical models (MCCM). We use data from ceilometers to detect the vertical distribution of the volcanic cloud. Ground-based in situ measurements of particle concentrations, sulphur dioxide and further parameters complete the data basis. The analysis concentrates on the spatial and temporal features of the event over Southern Germany. It is an initiative of a scientific cooperation on aerosols in the area of Augsburg (500 m altitude) - Munich (550 m) - Hohenpeißenberg (1000 m) - Zugspitze / Schneefernerhaus (2650 m). The period from the evening of April 15th to the evening of April 20th, 2010 is covered. Main emphasis is laid on shorter events: (1) the first 15 hours of April 17th when the first cloud moved over Southern Germany, (2) the night from April 17th to April 18th when a second puff arrived over Southern Germany, and (3) the afternoon of April 19th when another puff arrived over Southern Germany. Back trajectories are used to check the origin of the observed dust clouds. Results from the model simulations with MCCM for the whole period will be compared with the measurement results. We will draw conclusions about the predictability of such events, the abilities of numerical models, the possible relevance for near-surface air quality as well as the possible enhancements of existing observation networks and simulation systems.