Data Assimilation Meetings at Reading

Date Meeting type Speakers
8 August 2012 DARC seminar Javier Garcia-Pintado (UoR)
Assimilation of Satellite-based SAR for flood modelling with an ETKF
Satellite-based Synthetic Aperture Radar (SAR) has proved useful for obtaining information on flood extent, which, when intersected with a Digital Elevation Model (DEM) of the floodplain, provides water level observations that can be assimilated into a hydrodynamic model to decrease forecast uncertainty. This is most useful given that the number of operational flow/stage gauges is actually declining in the world. However, with an increasing number of operational satellites with SAR capability, information on the relationship between satellite first visit and revisit time and forecast performance is required to optimise the operational scheduling of satellite imagery. Here I will talk about the sensitivity of the forecast performance to satellite visit parameters by using an ETKF and a synthetic analysis with the 2D hydrodynamic model LISFLOOD-FP based on a real flooding case affecting an urban area (summer 2007, Tewkesbury, Southwest UK. A generic hydrologic-hydrodynamic modelling cascade is emulated by imposing a bias and spatiotemporal correlations to the inflow error ensemble into the hydrodynamic domain. First, estimation and correction for this bias leads to a clear improvement in keeping the forecast on track. Second, imagery obtained early in the flood is shown to have a large influence on forecast statistics. Revisit interval is most influential for early observations.

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