Stephen manages the Variational Data Assimilation (VAR) system and co-ordinates its implementation within the operational NWP forecasting suite.
Stephen's areas of expertise include:
Stephen is responsible for the maintenance and technical development of the VAR software system, including the code itself, the documentation system and the user interface. He provides support and advice to users and developers of the software along with producing regular stable releases for trialling and operational use, and portable releases for Met Office collaborators.
Stephen's recent focus has been the porting of Met Office codes and suites to ECMWF as part of the EURO4M project and the tuning of the VAR software to the IBM Power 7 Met Office HPC. The performance of the computationally demanding 4D-Var data assimilation scheme is becoming increasingly important with the move to increased core count, rather than increased clock speeds, and it is expected that the scalability and performance of VAR on new architectures will remain a challenge for some time to come.
Stephen is also responsible for the development and maintenance of a suite of integration acceptance tests which ensure that recent software changes conform to programming standards and that operational configurations of VAR are not adversely affected.
Stephen has been a member of the Observation Processing and Global Model Data Assimilation team, which is part of Data Assimilation and Ensembles, since he joined the Met Office in 2002. Prior to joining the Met Office, Stephen completed a PhD in computational astrophysics at the Department of Physics in the University of York.