Presentation on theme: "Preparing CMOR for CMIP6 and other WCRP Projects"— Presentation transcript:
1Preparing CMOR for CMIP6 and other WCRP Projects Charles Doutriaux and Karl E. TaylorPresented at the4th Annual ESGF & UV-CDAT MeetingLivermore, CA11 December 2014
2Outline What is CMOR (the Climate Model Output Rewriter)? What changes are planned?
3Why CMOR?PCMDI and now WCRP advocate adoption of common standards/conventions for the:Structure and format of climate dataMetadata used to describe climate dataVocabulary used for categorizing the diversity of model outputStandardization enables/facilitatesAutomation in the preparation of model outputAnalysis by researchers using uniform methods for reading and interpreting dataunique identification of filessharing of data across the ESGF networkBut model output stored in native formats following a diversity of approaches must be “translated” into the standard formCMOR was written to facilitate this.
4What is CMOR?CMOR is a library of C functions which facilitate/enforce compliance with MIP requirements.Includes interface to both Fortran and python codeCMOR was designed to be adapted to the different metadata requirements of each “model intercomparison project” (e.g., CFMIP, HTAP, PMIP)Most of the CMIP3 and CMIP5 output served by ESGF was processed through CMOR.CMOR has been key to ensuring uniformity across all models
5Project-specific CMOR tables facilitate and ensure consistency of model output from contributing groupsProper specification of coordinate and variable attributes, including:Correct standard names and unitsUse of a common time coordinate model (with flexibility)Required dimensions (but with different grids allowed)A capability toReorder axis orderReverse axis direction (or translate longitude dimension)Convert units (through udunits)
6What standards does CMOR ensure compliance with? netCDF – (www.unidata.ucar.edu/software/netcdf/)CF Conventions – provides for standardized description of data contained in a file (cf-convention.github.io)Data Reference Syntax (DRS) – defines vocabulary used in uniquely identifying MIP datasets and specifying file and directory names (cmip-pcmdi.llnl.gov/cmip5/output_req.html).CMIP output requirements – specify the data structure and metadata requirements for CMIP data (cmip- pcmdi.llnl.gov/cmip5/output_req.html)
7CMOR flags common errors, including Pointing out when required metadata are omitted.Rejecting incorrect metadata (wrong units, inadmissible attribute values, etc.)Rejecting inconsistent coordinate dimensions passed by user to CMOR.Rejecting non-monotonic coordinate values or inconsistent boundary values, as passed by user.Rejecting values that are clearly unrealistic (likely indicating improper units conversion or incorrect sign).
8CMOR history Original CMOR used in CMIP3 CMOR-2 used in CMIP5 Written in FORTRAN 95.accommodated only data stored on cartesian longitude-latitude grids.CMOR-2 used in CMIP5CMOR’s structure and functions were largely unchanged.Written in C (with FORTRAN 95 and python interfaces)Can write output on model “native” grids that are not cartesian longitude-latitude.Station data (needed, for example, by the HTAP project), including metadata for station names and station locationsRegional model output handled smoothly.Relies on netCDF-4 (rather than NetCDF-3), which provides for automated compression.
9What is planned for CMOR-3? Generalization to better handle a wider range of model output and observational data.CMOR was developed (and to a certain extent “hard-wired” to meet modeling needsSome of the attributes written by CMOR don’t apply to observations (e.g., model name, experiment name)Modifications are needed to simplify the reconfiguration of the input tables for each new MIP.Modularization of the CMOR input tables, separatingProject-specific metadata fromVariable information
10What needs to be done for CMIP6? Write and release CMOR-3Generate new CMOR tablesAllowing additional required global attributes? (e.g., version info.)Recognizing CMIP6 controlled vocabularyIncluding any new requested variables.Provide more complete QC information to CMOR (e.g., valid max and min for each field)Modularize the CMOR input tables to separately specifyProject-specific informationList of variables and their metadata
11For further information: https://github.com/PCMDI/cmor IssuesDocumentation