Eyjafjallaj?kull volcano ash plume operational monitoring all over Europe with ground based and airborne mounted Lidars

摘要

1. Introduction Volcanic emissions comprising steam, ash, and various gases are injected into the atmosphere and produce effects affecting- Earth's climate. Volcanic ash is composed of non-spherical mineral particles spanning a large size range. The largest ones are likely to sediment quickly not far from the eruption site. The ash component, and sulphate particles formed by subsequent oxidation of the SO_2 emission, pose a variety of hazards to humans and machinery on the ground, as well as damage to aircraft that fly inadvertently through ash plumes [1]. To mitigate such hazards, a network of nine backscattering ALS Lidars, produced by LEOSPHERE, provided plots of range corrected backscatter signal hourly to different agencies, and to VAAC coordinated by UK Met Office. The network, together with airborne mounted Lidar test flights; offered a fundamental support to the different civil aviation agencies in making decisions regarding flight safety. Recent determination of the extinction to mass conversion factor by optical modelling of ash cloud data allows estimating plume mass density from the Lidar measurements.