Heavy rain in Europe

Principal Investigator

Dr Kai Sattler
Danish Meteorological Institute
Lyngbyvej 100
2100 Copenhagen
Denmark

ksa@dmi.dk

Project description

The special project Heavy Rain in Europe will address heavy rain events over Europe. It includes NWP-model simulations using DMI-HIRLAM model in connection with the ECMWF modelling system. The work in this special project is strongly linked to the EU-project "A European Flood Forecasting System" (EFFS) supported by the European Commission.

The aim of the project, EFFS, is to establish a prototype of a flood forecasting system for 4-10 days in advance. This system shall provide daily information on potential floods for large rivers such as the rivers Rhine and Oder as well as flash floods in small basins. The flood forecasting system can be used as a pre-warning system to water-authorities that already have a 0-3 day forecasting system. The system can also provide flood warnings for areas that at present do not have a forecasting sys-tem (Eastern European Countries). The project consortium consists of three meteorological institu-tions (ECMWF, DWD and DMI) and several European hydrological institutes.

One aspect of the work is concerned with meteorological data collection and supply. DMI provides regional model forecasts with a model set-up derived from the current operational forecast system. A doubled nested model system of DMI-HIRLAM is used to scale precipitation fields dynamically down to a resolution of 0.3 and 0.1 degrees. The 0.3-degree model domain covers the entire North Atlantic as well as Europe. The innermost high-resolution model domain covers all important river catchments in Europe.

The ECMWF model serves as host model to the nested system of DMI-HIRLAM models. This combined model set-up will be used to investigate some selected cases with heavy rain in Europe. DMI-HIRLAM is initialised with ECMWF analysis from 12 UTC, and the model is updated with boundary data from the ECMWF model with 6 hour frequency. Each day within the period, a fore-cast is started 3 days ahead, and accumulated precipitations as well as other related surface vari-ables are supplied to the hydrological models with a frequency of 1 hour.

In addition to these deterministic hindcasts, it is planned to run a mini ensemble for a selected pe-riod. The ensemble of DMI-HIRLAM run will be based on the EPS of the ECMWF in a similar way.

Another aspect is concerned with estimation of the uncertainty of the precipitation forecasts, and it is planned to use two approaches. The first one is to run forecasts with different model configura-tions using the same initialisation and estimating the deviations in precipitation connected to this from the resulting ensemble of forecasts. The second approach is to run a targeted ensemble of fore-casts from the ECMWF ensemble prediction system (EPS). This mini ensemble approach is thought to account for uncertainty in the description of the dynamic state as such.

The work described above will necessitate large amounts of computer resources, both in CPU time and in storage capacity. As most of the simulations are closely linked to the ECMWF model output, and as ECMWF do participate in the project as well, it is considered most appropriate to carry out the simulations on the Fujitsu computer system at ECMWF.

Final report

Additional information

Project period 2001 - 2003.