Spatial evaluation of volcanic ash forecasts using satellite observations

Harvey, N. ORCID: https://orcid.org/0000-0003-0973-5794 and Dacre, H. ORCID: https://orcid.org/0000-0003-4328-9126 (2016) Spatial evaluation of volcanic ash forecasts using satellite observations. Atmospheric Chemistry and Physics, 16 (2). pp. 861-872. ISSN 1680-7316 doi: 10.5194/acp-16-861-2016

Abstract/Summary

The decision to close airspace in the event of a volcanic eruption is based on hazard maps of predicted ash extent. These are produced using output from volcanic ash transport and dispersion (VATD)models. In this paper an objectivemetric to evaluate the spatial accuracy of VATD simulations relative to satellite retrievals of volcanic ash is presented. The 5 metric is based on the fractions skill score (FSS). Thismeasure of skill provides more information than traditional point-bypoint metrics, such as success index and Pearson correlation coefficient, as it takes into the account spatial scale overwhich skill is being assessed. The FSS determines the scale overwhich a simulation has skill and can differentiate between a "near miss" and a forecast that is badly misplaced. The 10 idealised scenarios presented show that even simulations with considerable displacement errors have useful skill when evaluated over neighbourhood scales of 200–700km2. This method could be used to compare forecasts produced by different VATDs or using different model parameters, assess the impact of assimilating satellite retrieved ash data and evaluate VATD forecasts over a long time period.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/42601
Item Type	Article
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Copernicus Publications
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