High resolution modelling of wind fields for optimization of empirical storm flood predictions

Abstract

Abstract. High resolution wind fields are necessary to predict the occurrence of storm flood events and their magnitude. Deutscher Wetterdienst (DWD) created a catalogue of detailed wind fields of 39 historical storms at the German North Sea coast from the years 1962 to 2011. The catalogue is used by the Niedersächsisches Landesamt für Wasser-, Küsten-und Naturschutz (NLWKN) coastal research center to improve their flood alert service.The computation of wind fields and other meteorological parameters is based on the model chain of the DWD going from the global model GME via the limited-area model COSMO with 7 km mesh size down to a COSMO model with 2.2 km. To obtain an improved analysis COSMO runs are nudged against observations for the historical storms. The global model GME is initialised from the ERA reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF).As expected, we got better congruency with observations of the model for the nudging runs than the normal forecast runs for most storms. We also found during the verification process that different land use data sets could influence the results considerably.

Wind variability in a coastal area (Alfacs Bay, Ebro River delta)

“…In recent years, the application of numerical models in both the atmosphere and oceans has contributed to improving the understanding and description of this variability (Schaeffer et al, 2011). Moreover, modelling studies have revealed that the model resolution is a key factor for the correct representation of wind patterns, which could be essential in a correct prediction of flood episodes (Brecht and Frank, 2014) and could allow for the correct application of hydrodynamic modelling (Signell et al, 2005;Bignami et al, 2007). Several authors have described wind variability in lakes (e.g.…”