Numerical weather prediction

Research on numerical weather prediction (NWP) is conducted at FMI mainly within the framework of the international ACCORD (A Consortium for Convection-scale Modeming Research and Development) consortium that develops a so-called mesoscale weather forecast model. In addition to the Finnish Meteorological Institute, 25 similar institutes from across Europe and North Africa are participating in the program. Finland's share in development work is 2-3 person-years per year.

Until 2006, the development of a regional weather forecasting system at FMI took place as part of the international HIRLAM (High Resolution Limited Area Model) program, in which the Finnish Meteorological Institute has participated since its inception (1985). The first operational HIRLAM model was introduced in 1990 but has now been discontinued and replaced by a model called HARMONIE-AROME that hase been developed in co-operation with the French-led ALADIN model consortium. Thanks to its dense resolution (2,5 km), HARMONIE-AROME is able to describe e.g. flow structures creating rain showers.

Starting from 2017, operational weather forecast model calculations at FMI have been performed as part of MetCoOp collaboration with the National Meteorological Institutes of Norway, Sweden and Estonia using a HARMONIE-AROME-based weather model system MEPS (Mesoscale Ensemble Prediction System). The system produces so-called ensemble forecasts, i.e., multiple forecasts that are calculated in parallel from slightly different initial conditions and input. This kind of ensemble forecasting method can assess not only the development of the weather but also the uncertainty associated with the forecast. Operational forecasts are produced every 3 hours and extend to 66 hours. Additionally, an hourly run HARMONIE-AROME-based nowcasting system producing 9 hour forecasts is in use.

The activities of the group are strongly international, and in addition to research and operative maintenance, its members serve in many international NWP model development leadership positions. In addition to the operational maintenance and research in numerical weather prediction, the activities of the group include various applications of weather modelling e.g. in wind energy production and in wind turbine icing. The group members are also involved in numerous national and international R&D projects.

The main research topics, mostly related to numerical weather modelling (NWP) within the context of ACCORD, are as follows:

  • Limited area weather forecast models (LAM)

  • Short range rapid update weather forecasting (nowcasting)

  • Ensemble prediction systems in numerical weather prediction (EPS)

  • Weather forecast model data assimilation

    • satellites

    • snow

    • lake surface temperature

  • Radiation and the effect of aerosols

  • Forecast quality assurance

  • Renewable energy power production estimation

  • Icing phenomena in wind power production

  • Urban meteorology

  • High performance computing (HPC) in meteorology

The integration area of MEPS HARMONIE-AROME covers Scandinavia.
Integration area of the FMI's limited area weather forecast model HARMONIE-AROME (MEPS).