Stephan Siemen

Seconded Expert (DG-CNECT)
Forecast Department


Stephan Siemen is currently seconded as a Policy Officer to the European Commission in Luxembourg. As part of the Open Science and Digital Modelling unit at DG-CNECT he is involved in the work around the European Open Science Cloud (EOSC) and other research infrastructure initiatives across Europe. 

Before his secondment, Stephan was for almost a decade leading the Development Section at ECMWF. The section develops software and services to support core activities at ECMWF. The software enables researchers and analysts in and outside of ECMWF to en/decode, process, access, archive and visualise observations and forecast data. Service developments cover production services to handle forecast and archive data and web services to support users of ECMWF.  

Stephan was also involved in the management of multi-year projects like the pilot of the European Weather Cloud and the technical part of the IFShub project.

Stephan was directly involved in the development of the plotting package Magics and supported in general new developments on visualisations at ECMWF.

Professional interests:
  • Offering of cloud services for Big Data weather and climate data processing
  • Visualisation of meteorological data
  • Providing efficient access to large data sets
  • Software development methodologies and modern programming models & languages
Career background:


  • Policy Officer (SNE), Open Science and Digital Modelling unit, DG-CNECT, European Commission, 2021 - present
  • Head of Development Section, Forecast Department,  ECMWF, 2013 - 2021
  • Head of Graphics / Meteorological Visualisation Section, Operations Department, ECMWF, 2007 - 2013
  • Analyst working on Magics, Graphics Section, Operations Department, ECMWF, 2003 - 2007
  • Senior Research Officer, Propagation Laboratory, Mathematics Department, University of Essex, 2001 - 2003