Data assimilation for volcanic ash plumes using a satellite observational operator

Data assimilation for volcanic ash plumes using a satellite observational operator: A case study on the 2010 Eyjafjallajökull volcanic eruption

Fu, G.
Prata, F.
Xiang Lin, H.
Heemink, A.
Segers, A.
Lu, S.

2017

Using data assimilation (DA) to improve model forecast accuracy is a powerful approach that requires available observations. Infrared satellite measurements of volcanic ash mass loadings are often used as input observations for the assimilation scheme. However, because these primary satellite-retrieved data are often two-dimensional (2-D) and the ash plume is usually vertically located in a narrow band, directly assimilating the 2-D ash mass loadings in a three-dimensional (3-D) volcanic ash model (with an integral observational operator) can usually introduce large artificial/spurious vertical correlations. In this study, we look at an approach to avoid the artificial vertical correlations by not involving the integral operator. By integrating available data of ash mass loadings and cloud top heights, as well as data-based assumptions on thickness, we propose a satellite observational operator (SOO) that translates satellite-retrieved 2-D volcanic ash mass loadings to 3-D concentrations. The 3-D SOO makes the analysis step of assimilation comparable in the 3-D model space. Ensemble-based DA is used to assimilate the extracted measurements of ash concentrations. The results show that satellite DA with SOO can improve the estimate of volcanic ash state and the forecast. Comparison with both satellite-retrieved data and aircraft in situ measurements shows that the effective duration of the improved volcanic ash forecasts for the distal part of the Eyjafjallajökull volcano is about 6h. © 2017 The Author(s).

Environment
Environment & Sustainability
Urbanisation
2015 Urban Mobility & Environment
CAS - Climate, Air and Sustainability
ELSS - Earth, Life and Social Sciences

http://resolver.tudelft.nl/uuid:70c674f0-1177-4ce0-8f14-d1b3eb8511b4

https://doi.org/10.5194/acp-17-1187-2017

745606

Copernicus GmbH

1680-7316

Atmospheric Chemistry and Physics, 17 (17), 1187-1205

Funding details: ESA, European Space Agency Funding text: We are very grateful to the editor, three anonymous reviewers and the fourth reviewer Matthew Toohey for their reviews and insightful comments. We thank the European Space Agency (ESA) project-Volcanic Ash Strategic initiative Team (VAST) for providing the satellite data for the 2010 Eyjafjallajökull volcanic eruption. We thank Konradin Weber (University of Applied Sciences, Environmental Measurement Techniques, Düsseldorf, Germany) for providing the real-time aircraft in situ measurements. We thank Arve Kylling at NILU-Norwegian Institute for Air Research for his kind assistance with interpretations of volcanic ash cloud height. In this paper, we perform the ensemble-based data assimilation using OpenDA (open source software, www.openda.com). We would also like to thank the Netherlands Supercomputing Centre (SURFsara)

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