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Numerical weather prediction

Research on numerical weather prediction is conducted at FMI mainly within the framework of the international ACCORD (A Consortium for Convection-scale Modeling 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 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. The HIRLAM model with horizontal resolution of 7.5 km is still run four times a day. However, this model is no longer being developed. In 2006 the HIRLAM program partnered with the French-led ALADIN model consortium. The HARMONIE-AROME model, which is the result of this cooperation and is capable of 2.5 km resolution, is currently in operational use at the Finnish Meteorological Institute. Thanks to its dense resolution, the model is able to describe e.g. also flow structures creating rain showers. Starting from 2017, operational weather forecast model calculations have been performed as part of MetCoOp collaboration with the National Meteorological Institutes of Norway, Sweden and Estonia. In these, the HARMONIE-AROME system produces so-called ensemble forecasts, i.e., multiple forecasts are produced in parallel from slightly different initial conditions. 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 currently produced every hour and extend to 66 hours.

The integration area of HARMONIE-AROME covers Scandinavia, while that of HIRLAM includes Europe, Northern Atlantic, parts of northwest Canada, and Russia approxmately to the Ural mountains.
Integration areas of the two FMI's limited area weather forecast models (inner HARMONIE-AROME, outer HIRLAM).

9.9.2021