We are pleased to welcome James Harris to this weeks Hotstuff Seminar to present a talk on GAEVA: Modelling Multiple Volcanic Eruptions to Investigate Global Fine Ash Exposure.

Abstract

The Global Atmospheric Exposure to Volcanic Ash (GAEVA) masters project was the development of a prototype ash cloud simulation to monitor multiple volcanic eruptions in a 1-layer atmosphere. A new prediction model was necessary to investigate the transport and fallout of fine ash (less than 63μ) in the atmosphere, which due to grain size and mass can be suspended between week-long and month-long timescales. Given ash producing volcanic eruptions overlap throughout the year, ash clouds can overlap, resulting in global ash exposure. Current models such as NAME and HYSPLIT are computationally expensive to run for long term predictions, necessitating a simple simulation to capture the required month to year time frames.

Developing GAEVA on the python platform, the prototype incorporates the Smithsonian Institute List of Holocene Volcanoes and NOAA’s NECP Reanalysis II vectored month-averaged wind data as key inputs. Research focused on incorporating source input, dispersion and fallout eulerian geophysics with volcanology to match observed ash transport at low computational expense for standard hardware. GAVEA Version 5 was successful in processing 1324 volcanic ash clouds with each day taking 0.4s to process. Multiple ash cloud interactions can be observed with time across the globe, with regions such as Central America and South East Asia having a high ash load. Good visual correlations with NOAA’s HYSPLIT was also achieved for Fuego Guatemala and Sakurajima Japan, however full correlation was difficult due to the differing physical modelling of both programs.

GAVEA has provided the foundations for long term fine ash predictions. Further improvements are needed such as a multi-layer atmosphere, switching wind fields for each elapsing month and greater input control of the program. This would allow GAEVA to better reflect the atmospheric conditions observed in the atmosphere and adapt the program accordingly. In the long term, GAEVA could provide running information for regions with high ash exposure permitting aviation operators to rotate aircraft on key routes to mitigate accelerated damage.