90 likes | 200 Views
GALEON – NERC/CCLRC experience. Andrew Woolf ( A.Woolf@rl.ac.uk ) e-Science Centre, CCLRC Rutherford Appleton Lab Acknowledgments: Dominic Lowe (British Atmospheric Data Centre) Jon Blower (NERC Environmental Systems Science Centre)
E N D
GALEON – NERC/CCLRC experience Andrew Woolf (A.Woolf@rl.ac.uk) e-Science Centre, CCLRC Rutherford Appleton Lab Acknowledgments: Dominic Lowe (British Atmospheric Data Centre) Jon Blower (NERC Environmental Systems Science Centre) Nathan Bindoff, Glenn Hyland, Jason Roberts, Ian Cummings (Tasmanian Partnership for Advanced Computing) NERC DataGrid team
Recommendations • Consider CSML ‘Grid’ for irregular grid domains <Grid srsName="urn:EPSG:geographicCRS:4979" srsDimension="3" dimension="2"> <gml:limits> <gml:GridEnvelope> <gml:low>0 7</gml:low> <gml:high>0 13</gml:high> </gml:GridEnvelope> </gml:limits> <gml:axisName>gridI</gml:axisName> <gml:axisName>gridJ</gml:axisName> <ordinate> <gridAxesSpanned>gridI gridJ</gridAxesSpanned> <sequenceRule order="+y+x">Linear</sequenceRule> <definesAxis xlink:href="#Lon"/> <axisValues> 1.00 1.10 1.20 1.30 1.40 1.45 1.50 1.55 1.60 1.50 1.45 1.35 1.30 1.20 1.10 1.18 1.27 1.36 1.46 1.48 1.57 1.65 1.71 1.62 1.58 1.50 1.48 1.40 ... </axisValues> </ordinate> ... </Grid>
Recommendations • Support New Work Item Proposal for ISO 19111 (Spatial referencing by coordinates - extension for parametric values), OGC 06-013 (some informative examples motivated by CF conventions) Scope: “To define an extension of ISO 19111:2005 covering coordinate referencing systems where the coordinates are physical or material properties measured by parameters, such as pressure, rather than linear distance measurements. It defines a conceptual schema for the description of spatio-parametric coordinate reference systems. These parametric spatial reference systems will be modelled so that they may be associated with an ISO 19111 [horizontal] spatial coordinate reference system to form a compound spatio-parametric coordinate reference system.”
Recommendations • Rationalise binary encoding in GML (for coverage range and domain) <gml:RectifiedGridCoverage gml:id="netcdf_ID0"> <gml:RectifiedGridDomain xlink:href="http://myserver/myfile.nc#temperature" xlink:role="http://netcdf/GMLOps/Grid/spatialDomain"/> <gml:rangeSet> <gml:File> <gml:rangeParameters> <gml:Quantity uom="degC"/> <fileReference>http://myserver/myfile.nc#temperature </fileReference> <fileStructure>Record Interleaved</fileStructure> <mimeType>application/x-netcdf</mimeType> </gml:rangeParameters> </gml:File> </gml:rangeSet> </gml:RectifiedGridCoverage>
Recommendations • Add “CF-netCDF” to allowed formats • HDF netCDF • HDF-EOS CF-netCDF • BBOX clarification w.r.t. CRS • e.g. EPSG:4979 (lat, lon, height) • BBOX=lat1,lon1,height1,lat2,lon2,height2, not • BBOX=minx,miny,maxx,maxy,minz,maxz ü
Recommendations • Harmonise WMS, WCS: BBOX and ELEVATION • WCS 1.0.0:BBOX=minx,miny,maxx,maxy,minz,maxz • WMS 1.3.0:BBOX=minx,miny,maxx,maxy&ELEVATION=minz/maxz/resz
Recommendations • Eliminate mandatory WIDTH (RESX), HEIGHT (RESY), DEPTH (RESZ) • to enable arbitrary slicing through four dimensions • e.g., Hovmüller (timeseries) of winds from 110-190EBBOX=110,-45,190,-45,1000,1000&TIME=2004-08-01/2004-08-31 HEIGHT (RESY) and DEPTH (RESZ) irrelevant
Recommendations • Clarify interpolation vs subsampling • netCDF API:nc_get_vars_*(ncid,varid,start,count,stride,buf) • OPeNDAP:http://opendapserver/dataset?var[start:stride:stop] • WCS should support subsampling • behaviour of INTERPOLATION? • Conventions for exposing netCDF attributes in WCS metadata, e.g.: • netCDF variable name WCS ‘CoverageOffering/name’ • CF ‘long_name’ WCS ‘CoverageOffering/label’ • CF ‘standard_name’ WCS ‘CoverageOffering/rangeSet/RangeSet/label’
Recommendations • Clarify roles of ‘temporalDomain’ and ‘spatialDomain/EnvelopeWithTimePeriod’ • unclear whether ‘temporalDomain’ mandatory for time-dependant data Experimental WCS (and full report) at: http://glue.badc.rl.ac.uk/cgi-bin/TPAC/WCS