On June 28th 2021, the selection commitee for the ESiWACE2 User Service 2 granted the offered 2 person-months of XIOS Dedicated User Support.

4 proposals were submitted to answer the 2021 call for Dedicated User Support for XIOS.

  • The Met Office (UK) applied for the development of a specific functionality in XIOS, i.e. the support of parametric vertical coordinates described in the CF standard, in order to consolidate its use of XIOS in their new LFRic atmosphere model.
  • CNRM (France), through two groups in Toulouse (GMGEC, GMME) and one in Grenoble (CEN), asked for support for the use of XIOS in the surface modelling platform SURFEX, both to consolidate and to improve its current interfacing and to extend its use to different applications using SURFEX, which would also require additional developments.
  • Mercator-Ocean and LOCEAN-IPSL (France) mainly target the implementation and optimization of the input functionality of XIOS in order to decrease the overhead observed when reading the new ERA5 reanalysis, which has a higher spatial and temporal resolution than the previous ERA-interim reanalysis.
  • CMCC (Italy) asks for general support to improve the performance of XIOS in the NEMO ocean model in their 1/16 and 1/36 degree global resolution.


The committee analysed and discussed the proposals guided by the following considerations:

  • The support should benefit well-constructed proposals that describe some precise and specific tasks, benefiting the applicant but also interesting for the development of XIOS. This is the case for all proposals but for the CMCC one, which was somewhat vague and general. Also, the CNRM proposal, although very interesting, seemed to be a bit overambitious in that respect and it was not so clear if satisfactory results could be obtained in the timeframe of 2 PMs maximum.
  • Given the fact that in-place support will most probably still not be possible in the coming year, the support should target tasks that will be easily achievable remotely or that involve easily accessible computing platforms. This is the case for the MetOffice proposal, which mainly involves development that can be done on any platform and the Mercator-Ocean and LOCEAN-IPSL one, whose platforms are already accessible to XIOS developers.
  • The support should help extend or consolidate the XIOS community beyond the current well-established users, increase its credibility and visibility, possibly outside of France. This was a strong argument in favor of the UK MetOffice proposal and for the Mercator-Ocean and LOCEAN-IPSL one, as it targets a development that is potentially beneficial for all NEMO users.

In conclusion, the committee decided to split the support into 2 x 1 PMs and to allocate 1PM to the UK Met Office and 1 PM for the Mercator-Ocean and LOCEAN-IPSL proposals. This decision is coherent with the global analysis done by the committee and with the technical assessment of the proposals.

Selection committee members: John Dennis, Ben van Werkhoven, Sophie Valcke