1. © Crown copyright Met Office SRNWP Interoperability Workshop, ECMWF, 14-15 January 2008 SRNWP Interoperability Terry Davies Met Office

2. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Contents This presentation covers the following areas Introduction Why? How? Discussion

3. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Why interoperability? Business continuity Initial and lateral boundary conditions Comparison, verification Ensembles Sub-models, e.g. surface model

4. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 How to achieve interoperability Regular/routine data exchange. Convert between model data formats through agreed common format.

5. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Flowchart from first draft interoperability proposal

6. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Simple flowchart of typical NWP or climate suite

7. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Simple flowchart of typical NWP or climate suite plus imported or exported data in common format

8. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Common format structure – Header(s) Coded (GRIB) or self describing (NetCDF) Header per record (GRIB) or for collection of records (NetCDF) Main header + sub-headers (NetCDF)

9. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 2D records (GRIB) or 2,3 or 4D records (NetCDF) Number format – 64-bit IEEE? Leave as native? i.e. model level Will need pressure/height converters Horizontal Grids Rotated lat-lon, spherical harmonics, Gaussian, Cubed sphere, Icosahedral, Ying-Yang Lateral boundary frames, variable resolution, Schmidt transform, reduced grids, Staggered grids Common format structure – Data Vertical Grids

10. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Reconfiguration Putting data in a form used by a particular model configuration. May include change of domain e.g. global to LAM, lateral boundary conditions. May include horizontal and/or vertical interpolation. May include changes to non-atmosphere variables – ancillary fields e.g orography, surface/soil fields (temperature, moisture, vegetation, ice, snow etc.), aerosols, chemistry.

11. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Reconfiguration issues I Models using different atmosphere variables e.g. hydrostatic/non-hydrostatic, (potential) temperature, specific quantities or mixing ratios etc. Models using different grids e.g. pressure or height based, grid-point or other, staggered/skipped etc. Different ancillary fields e.g. surface/soil fields (land use, vegetation, ice, snow, lakes etc.), aerosols, chemistry.

12. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Reconfiguration issues II Where models use different algorithms or science then need to exchange information to execute appropriate data conversions. May find it convenient to mix & match i.e. import atmosphere data but use own ancillary data. Allow mix & match only to begin with and add ancillary conversions later.

13. © Crown copyright Met Office SRNWP Interoperability Workshop ECMWF 14-15 January 2008 Interoperability programme Agree to where data exchange should fit into archetypal suite structure. Specify supported common formats Allow more than 1? Agree on technical details supported by common formats. Common format documentation and user manual Each consortium to develop its own conversion programs to and from the common formats. Consortia to exchange any algorithmic details required for reconfiguration.

14. © Crown copyright Met Office SRNWP Interoperability Workshop, ECMWF, 14-15 January 2008 Questions and answers