The Modelling group is involved in the study of weather processes, including their predictability, and the development of improved or new parameterizations of these processes, in order to gain knowledge about atmospheric dynamics and the improvement of atmospheric models. The group is well recognized internationally and participates actively in the HIRLAM R&D project, both management and research and development.

Although the synoptic HIRLAM model is still the vehicle for general weather forecasting (with a focus on severe weather prediction and aviation forecasts), the focus of the research within the group has shifted from the synoptic scale to the mesoscale meteorology. The group creates and maintains a state-of-the-art model environment - currently this means e.g. using variational data-assimilation methods (3D-VAR) within the HIRLAM suite and implementation of the nonhydrostatic model HARMONIE. The group contributes to an improved understanding of what is required for hazardous weather forecasts, and to the development of a probabilistic forecasting system GLAMEPS based on limited area model ensembles. For example, by implementing a new combined turbulence/convection (EDMF) scheme, modifying the cloud scheme, or by developing CAPE singular vectors, which are designed to trigger convection.

The customers of products resulting from improved performance of different models are numerous within KNMI (notably of HIRLAM), within the government agencies, in the public sector and within commercial companies, the water boards, the Ministry of Infrastructure and the Environment. Also systems and data are made available to stimulate research in the academic community that contributes to better understanding of atmospheric dynamics and to improving meteorological models. The group participates in international consortia carried out with financial support of EU, EUMETNET, e.g. GEOLAND, COST, GABLS2/3, CLEOPATRA.

The work within the Observations group concentrates on the generation and application of products derived from ground-based observations (both in-situ and remote sensing) and satellite remote-sensing observations.
The main topics of our research are (i) Sea Surface Winds using Scatterometers; (ii) Precipitation: using weather radars or passive imagers; (iii) Wind Profiling: using space based profiling lidars (AEOLUS); (iv) Clouds and Radiation: using passive imagers (SEVIRI, AVHRR, MODIS); (v) Atmospheric Water Vapor: using GPS observations. The work within the Data Assimilation group concentrates on the use of observations by the operational HIRLAM model and the experimental HARMONIE model. A tool has been developed to monitor the quality of the incoming observations and their impact on the analysis and forecast quality. In addition, an experimental environment was set up to test the use of new observation types. Currently, the main focus is on high-resolution observations such as from scatterometer ocean surface winds and Mode-S aircraft wind and temperature measurements. These are tested semi-operationally on their additional value for short-term weather forecasting. More fundamental research focuses on a relatively new assimilation technique called particle filtering. The subjects covered by the Applications and Post-processing group range from air-sea interaction research and maritime applications to statistical post-processing and verification of in principle all models that are used operationally at KNMI. The focus in the medium range is of course on ECMWF EPS products. For the shorter forecast ranges emphasis is on applications and post-processing research on HIRLAM and GLAMEPS, in future on HARMONIE. Therefore there is an intimate relation to the work performed in the modelling group.

Much of the effort is devoted to research to improve statistical (mainly probabilistic) forecasting methods for atmospheric and maritime quantities, particularly aimed at the extremes of the probability distribution. Especially, methods to aid decision making by operational forecasters regarding the issuance of extreme weather warnings and weather alerts. Also the development of new and improvement of existing statistical forecasting systems and verification of their performance is part of the work, again with emphasis on the extremes.

Another important research topic is in the field of verification methods and benefit and how to evaluate the impact of meteorological information and products.
Advisory and educational tasks are performed with regard to methods and products of this group to people inside and outside KNMI. Maintenance of an extensive data base of (post-processed) numerical output of a number of atmospheric and storm surge models is needed for the above-mentioned research and development.