HARMONIE-AROME for North Sea Forecasts
The new standard model for regional weather forecasting is HARMONIE-AROME. The intent is
to replace the use of Hirlam data in all applications by HARMONIE-AROME. Rijkswaterstaat (RWS)
has several maritime applications that use Hirlam data, e.g. for storm surge forecasting
on the North Sea up to 48 hours ahead.
The domain of the HARMONIE-AROME model as used by KNMI is not large enough for even the previous
version of the storm surge model (DCSMv5). Therefore, HARMONIE-AROME data have to be extended
to cover the complete domain of the storm surge model.
To extend the HARMONIE-AROME domain, data of the model that supplies the lateral boundary
conditions for HARMONIE-AROME itself can be used. HARMONIE-AROME (as of version 38) takes its boudary
conditions directly from the ECMWF IFS model, which are readily available from the ECMWF
For the validation of HARMONIE-AROME input for RWS applications, reforecasts have been produced
for a number of storm surge cases in the past and also for the complete years 2015, 2016
and 2017, and, separately, the winter season September 2017 – March 2018. We used these
at KNMI to generate storm surge forecasts with the WAQUA/DCSMv6 model. As a comparison,
also ECMWF input has been used.