The weather and climate models developed and used at our department are complex computer programs. I assist researchers in our group to use these models and try to improve them, for example their input/output and user-friendliness. In the past I have mainly worked with the regional climate model RACMO, which has been used in many studies and for the climate scenarios for the Netherlands. Currently I am exploring the use of the NWP model HARMONIE-AROME as a climate model, which can be run at a higher resolution than RACMO, but is also more expensive to run. Also I have become part of the group of people that is responsible for running the weather models HIRLAM and HARMONIE operationally.