Le lundi 11 janvier 2016, nous aurons l’occasion de se réunir autour de la présentation de Thomas Aubry .
A cette occasion Thomas nous parlera de ses travaux sur : “Scaling Heights for Volcanic Plumes Rising Under Wind Stress: Comparison Using Analogue Laboratory Experiments and Observations“.
Voici un résumé de sa présentation :
The maximum height of volcanic plumes rising into Earth’s atmosphere is governed mostly by the atmospheric stratification, the rate of turbulent entrainment of atmospheric air into the plume, the buoyancy flux at the vent and wind. Turbulent entrainment is commonly assumed to increase proportionally with the average plume rise velocity and the wind stress. There exist multiple scalings linking eruption source conditions to plume height. However, scalings validation is often based on: i) analogue experiments that do not capture the full range of dynamical conditions under which explosive eruption occur; ii) direct observations of a restricted number of eruptions; or iii) numerical models with parametrized turbulent entrainment physics.
In this study, we derive a new analytical scaling and compare it with existing analytical and empirical scalings commonly used in the literature. We use extensive analogue laboratory experiments on buoyant jets rising into a uniform wind field (Carazzo et al., 2014) and a set of observations from 27 explosive eruptions (Mastin, 2014) to test each scaling. A key outcome of our work is the refinement of existing constraints on entrainment coefficients. Finally, we discuss the importance of plume height predictions for the evolution of volcanic forcing in a changing climate.
Ce Volcapot se déroulera à 14h en salle Jean Jung.