Fine Tuning Eruption Source Parameters to Improve Ash Dispersion Simulations: An Example From Eyjafjallajökull 2010

Volcanic ash dispersion simulations and remote sensing of ash clouds are conducted by volcano observatories and Volcanic Ash Advisory Centres to monitor and forecast the evolution of volcanic ash clouds in space and time in order to mitigate the risk posed by these events on civil aviation. Despite constant improvements in terms of technology and modern capabilities, both numerical simulations and monitoring are still affected by variable degrees of uncertainty. To initialize the rate of emission and position of the volcanic ash in the ash dispersion simulation computational domain of the numerical model used for forecasting the ash clouds, in particular, currently relies on the preliminary simulation of the volcanic plume. The source modeling is generally carried out using simplified plume models that depends on parameters that cannot be accurately measured in real time, for example, the wind entrainment coefficient and the plume centerline height in case of wind affected (bent-over) plumes. In this work, we test recently proposed correction factors for these parameters for two of the most widely used simplified plume models and compare with ash cloud satellite observations retrieved during the Eyjafjallajökull eruption. Specifically, we compare modeling results obtained with and without applying the corrections of the top plume height and wind entrainment coefficient. We show that, by applying the corrections, we significantly reduce the discrepancy between the simulated and satellite-retrieved ash cloud observations.