Volcanic ash modeling with the online NMMB/BSC-ASH-v1.0 model

Alex Marti
Barcelona Supercomputing Center
Noon Dec 15 in Room 2155

Large explosive volcanic eruptions can inject significant amounts of tephra (ash) and aerosols (e.g. SO2) into the atmosphere inducing a multi-­scale array of physical, chemical and biological feedbacks within the environment. Volcanic Ash Transport and Dispersal (VATD) models are used to simulate the atmospheric transport, dispersion and ground deposition in order to generate operational short-term forecasts that support civil aviation and emergency management. In addition, other model applications include reconstruction of past events, probabilistic hazard assessments or simulation of recent eruptions for model evaluation purposes. In all cases, the modeling system involves a driving Numerical Weather Prediction (NWP) model or a meteorological reanalysis dataset, an emission or source model for the eruption column (volcanic plume) and the VATD. Traditionally, VATDs have evolved decoupled (offline) from NWPs. Although this common approach has advantages from the operational point of view, it can lead to inaccurate handling of atmospheric processes with time scales smaller than the NWP output frequency and neglects eventual feedback effects of the volcanic pollutants on local-scale meteorology. The aim of this talk is to present and describe the NMMB/BSC-ASH, a new on-line model to simulate the emission, transport and deposition of tephra particles released from volcanic eruptions. The model builds on the NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM), which we have modified to account for the specifics of volcanic particles. The final objective in developing the NMMB/BSC-ASH model is two-fold. On one hand, at a research level, we aim at studying the differences between the online/offline approaches and the role of feedback effects of dense volcanic ash clouds on the radiative budget and regional meteorology. On the other hand, at an operational level, the low computational cost of the NMMB dynamic core suggests that NMMB/BSC-ASH could be applied in a future for more accurate online operational forecasting of volcanic ash clouds.