Strengths and weaknesses
The novelty of the approach is to closely link expertises in two distinct fields, which had so far very little interaction but which, in the context of this GDRE, will (at least partly) be unified. The aim of this work package is to characterize the physical parameters of the volcanic source to be injected into volcanic plume and atmospheric models as a function of distance from the vent and up to its maximum height. The strength of our multi-disciplinary approach is to combine sophisticated measurements close to the volcano with models adapted to the specificity of volcanic sources. Indeed results from studies solely focused in one area can conflict among themselves but also with studies from other areas, hence the need for a multi-disciplinary approach. Furthermore one technique may give important constraints that other needs. Another benefit is the expertise of both communities to improve volcanic plume models, especially in the buoyant cloudy part of the plume.
The first pitfall is related to the fast evolution of the physical and chemical parameters on a small vertical scale just above the vent and the size of the grid used by atmosphere scientists. The second difficulty arises from the incomplete knowledge of both the high-temperature chemical reactions, also tackled by WP1, and the grain-size distribution. Models of atmospheric circulation, which are very complex, computationally expensive and partially based on a number of oversimplified assumptions, need to be tested with field correlative measurements to ensure validity and robustness. A third major difficulty arises from the need to constrain the time and space evolution of the mass, energy and momentum contribution of secondary sources. Indeed, their interaction with the convective system developed above the eruptive vent can modify substantially plume ascent and dispersion (e.g. Di Muro et al., 2004; Durand et al., 2014).