|Combination of ceilometer and cloud radar measurements for volcanic ash detection and quantification|
The combination of ceilometer and cloud radar measurements at Mace Head provides information on the vertical distribution of possible volcanic ash layers in near real-time (every 15 minutes). The depolarisation data of the cloud radar can be used to distinguish spherical from non-spherical particles. Volcanic ash is known to be non-spherical. However, the cloud radar is limited to large particles. Aerosol layers with sufficiently large non-spherical particles are classified as such (red scale). This does not mean, that all other aerosol layers consist only of spherical particles. It rather indicates, that the particles are too small to be detected by the radar.
The algorithm for aerosol detection has been developed by the Centre for Climate & Air Pollution Studies (C-CAPS) in Galway.