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climate science modelling language version 2 user's manual

1. lt complexType name ReferenceableGridPropertyType gt lt sequence gt lt element ref csml ReferenceableGrid gt lt sequence gt lt attributeGroup ref gml OwnershipAttributeGroup gt lt complexType gt The csml GridCoordinatesTable is defined as follows lt complexType name GridCoordinatesTablePropertyType gt lt sequence gt lt element ref csml GridCoordinatesTable gt lt sequence gt lt attributeGroup ref gml OwnershipAttributeGroup gt lt complexType gt lt element name GridCoordinatesTable type csml GridCoordinatesTableType substitutionGroup gml AbstractObject gt lt complexType name GridCoordinatesTableType gt lt annotation gt lt documentation gt Defines a table providing the transformation between grid coordinates and external coordinate reference system see ISO 19123 8 2 1 Allows all grid point locations to be listed explicitly using the gml gridPoints property or individual ordinates to be listed for each coordinate system axis using a set of gml gridOrdinate elements one for each axis of the coordinate reference system lt documentation gt lt annotation gt lt choice gt lt element name gridOrdinate type csml GridOrdinateDescriptionPropertyType maxOccurs unbounded gt element name gridPoints type csml GridPointDescriptionPropertyType gt lt choice gt lt complexType gt 10 2 GridPointDescription GridPointDescriptionType GridPointDescriptionPr
2. workshop findings and outcomes Online http www metoffice gov uk informatics DGC Web Services and GML Modelling for Operational Meteorology communique_V1 pdf 31 January 2007 03 Feb 2007 59 Climate Science Modelling Language Version 2 xvii Cox S ed 2003 Observations and Measurements OpenGIS Consortium document 05 08r4 Online http portal opengeospatial org files artifact_id 17038 31 January 2007 xviii Woolf A Climate Science Modelling Language Version 0 1 User s Manual 9 Jan 2005 Online http ndg nerc ac uk csml UsersManual pdf 31 January 2007 xix Andrew Woolf Bryan Lawrence Row Lowry Kerstin Kleese van Dam Ray Cramer Marta Gutierrez Siva Kondapalli Sue Latham Kevin O Neill Ag Stephens 2005 Climate Science Modelling Language standards based markup for metocean data 85th Annual Meeting of the American Meteorological Society San Diego Jan 2005 xx Object Modelling Group UMG Unified Modeling Language Specification Version 1 5 Mar 2003 xxi Woolf A GML Change Request for ReferenceableGrid OGC document 06 160r1 20 Nov 2006 i j 1 1 Feb 2007 xxii W3C 2001 XML Linking Language XLink Version 1 0 27 June 2001 Online http www w3 org TR xlink 2 Feb 2007 03 Feb 2007 60
3. Climate Science Modelling Language Version 2 cd Domain geometries TM_Object Temporal Objects TM_Complex ObjectT ype TimeSeries timePositionLis Sequence lt TM_ Instant lt complexType name TimeSeriesType gt lt complexContent gt lt extension base gml AbstractTimeComplexType gt lt sequence gt lt element ref csml timePositionList gt lt sequence gt lt extension gt lt complexContent gt lt complexType gt lt element name TimeSeries type csml TimeSeriesType substitutionGroup gml AbstractTimeComplex gt lt complexType name TimeSeriesPropertyType gt lt sequence minOccurs 0 gt lt element ref csml TimeSeries gt lt sequence gt lt attributeGroup ref gml OwnershipAttributeGroup gt lt attributeGroup ref gml AssociationAttributeGroup gt lt complexType gt Figure 20 CSML TimeSeries Figure 21 gives an example encoding a time series of 30 fortnightly time instants in a calendar of 30 day months assumed defined elsewhere lt TimeSeries gml id times0001 gt lt timePositionList frame ndg calendar 360day gt 2007 01 15 2007 01 30 2007 02 15 2007 02 30 2007 03 15 2007 03 30 2007 04 15 2007 04 30 2007 05 15 2007 05 30 2007 06 15 2007 06 30 2007 07 15 2007 07 30 2007 08 15 2007 08 30 2007 09 15 2007 09 30 2007 10 15 2007 10 30 2007 11 15 2007 11 30 2007 12 15 2007 12 30 2008 01 15 2008 01 30 2008 02 15 2008 02 30 2008 03 15 2008 03 30 lt timeP
4. The notion of processing affordance was proposed by the workshop as a means to capture the joint concept of the operations allowed on a feature type together with the structural elements required to support them e g extracting a pseudo radiosonde is a feature type operation that requires a four dimensional gridded timeseries structure to support it Thus processing affordance may be regarded as a binding between the operations that may be performed on an object with structural properties of the object required to support those operations This matches closely the conventional UML concept of a type A Type is used to specify a domain of objects together with operations applicable to the objects without defining the physical implementation of those objects A Type may not include any methods but it may provide behavioural specifications for its operations It may also have attributes and associations that are defined solely for the purpose of specifying the behaviour of the type s operations xx The match is not exact since the attributes and associations of a type are not required to be inherited by an implementation class It was recognised at the workshop that CSML might benefit from modelling the operations supported by the sampling geometries that characterise CSML feature classes This has been implemented in CSML v2 using the conventional UML stereotype type avoiding any requirement for more radical extens
5. lt element ref csml timePositionList gt lt choice gt lt complexType gt NOTE Spatiotemporal compound coordinate reference systems are explicitly intended to be supported for coverages over spatiotemporal domains see the NOTE at GML clause 20 3 4 While the definitions above support referenceable grid geometries over such domains additional changes are required to support rectified grid and other geometries over spatiotemporal domains for instance gml offsetVector does not support temporal offsets 03 Feb 2007 58 Climate Science Modelling Language Version 2 REFERENCES i Woolf A et al 2003 Data Virtualisation in the NERC DataGrid UK e Science All Hands Meeting Nottingham UK Online http www nesc ac uk events ahm2003 AHMCD pdf 094 pdf 26 July 2004 ii A Woolf B Lawrence R Lowry K Kleese van Dam R Cramer M Gutierrez S Kondapalli S Latham D Lowe K O Neill A Stephens 2006 Data integration with the Climate Science Modelling Language Advances in Geosciences 8 83 90 Online http direct sref org 1680 7359 adgeo 2006 8 83 31 January 2007 iii Woolf A Lawrence B Lowry R Kleese van Dam K Cramer R Gutierrez M Kondapalli S Latham S and O Neill K 2005 Standards based data interoperability for the climate sciences Met Apps 12 1 9 22 doi 10 1017 51350482705001556 iv ISO 19101 Geographic information Reference mod
6. the ReferenceableGrid is used for the domain 03 Feb 2007 41 Climate Science Modelling Language Version 2 6 FILE INTEGRATION The mechanism for integrating file based data in CSML was outlined in section 1 2 There are two components to the approach 1 a conceptual model of feature types is defined and feature instances are encoded using GML omitting any content that conceptually comes from files 2 a storage descriptor schema is used to describe logical extraction of data from storage The mapping of the latter into the former is achieved using a specific xlink pattern described in section 6 2 below The CSML feature collection and storage descriptors exist in two logically separate XML documents but for convenience they may be grouped together using the CSML Dataset element as described in section 3 3 This chapter describes in detail the CSML storage descriptor and the xlink mechanism 6 1 CSML StorageDescriptor The conceptual model for the CSML StorageDescriptor is shown in Figure 40 cd StorageDescriptor descriptor 0 component Figure 40 CSML numeric array definition 03 Feb 2007 42 Climate Science Modelling Language Version 2 The following four array descriptor subclasses are defined e InlineArray an inline character encoding of array values e ArrayGenerator a formulaic expression implicitly generating array values e FileExtract value
7. conceptual modelling of important community feature types with model driven serialisation into standardised XML representations On the other hand compatibility with existing 03 Feb 2007 6 Climate Science Modelling Language Version 2 infrastructure and efficiency of storage demands the continuing use of community data formats In fact both are needed The CSML solution formalises the working habits of practitioners who don t plan their activities in terms of low level file formats but rather at a higher conceptual level For instance a researcher may wish to calculate the annual average surface temperature over continental Europe The conceptual model held by the researcher is of a field of temperature data extending over the Earth s surface and vertically and varying in time over some number of years Regardless of the actual representation of the data be it in one or more netCDF files or GRIB 2 d layers or in pages of an Excel spreadsheet it is clear that this representation can always be logically mapped onto the conceptual view otherwise the researcher s task would not be possible The mapping might not be straightforward e g it might involve extracting and aggregating arrays of data from many hundreds of files but it is logically possible Thus we arrive at the CSML model for interoperability It consist of two components Figure 3 1 a conceptual model of information capturing essential feature types ind
8. FeatureCollectioni ii ia asian rite tee eerte Ere eee ie LL ERE x v ave Poet de 16 3 2 CSML 5toraseDescmpltoto ases atom nias alb aate asi ten ec 17 3 3 CSME Dataset Wrap per za etie elia 18 3 4 Local dictionaries uui a Ed bete riali 18 SAL vPhemomenoNi s lina tere ete cett eet terti dass 18 BAD iUntdetfinitionsc uie casn ne e e EN Eb PES ua 19 obo Reference system detinitionsi irta alla 19 p EU E I A o iiaa Ee ie EAEE NETESE EA E EEEN 21 4 1 TimeValueList TimePositionListType timePositionList TimeSeries 21 4 2 CSML ReferenceableGrid eene enne enne enne erret eene rana ccoo 22 D COME PRATT CA Vesco Lea lo 25 5 1 ReferenceableGrid subclasses eere enne nennen ennt rana conos 27 5 2 CSME coverape types osos Nep mp sateen dpa uh Sel corneas 27 5 3 CSML Feature Types rara 28 Sar Pomette aiii tii 29 bi32 A TO 30 5 99 Lfjectory Feature sarei 31 5 3 4 PointCollectionFeature eee 32 5 95 vProfil Feat re e tera e pee eere trap ea 33 5 3 6 ProfileSeriesFeature eene enne ee enne ennt tret teen eere n tense tenen nnn 34 529 7 RaggedProfileSenesFesture iano 35 03 Feb 2007 Climate Science Modelling Language Version 2 53 8 Sectionbeat re n alla NER Dd e 36 Dod RageedoechonFeatute uq en nap ia 37 5 3 10 ScanningRadarFeatute AAA b o RE QE rene 38 5 3 11 Gridbeat lre ui
9. amp M A m TERR SWEBase has TimeGrid and timePositionList Sequence TM Instant TimelnstantGrid for regular temporal spacing also TimePositionList for arbitrary sequence of times Figure 28 CSML PointSeriesFeature UML model The attributes are location the spatial location from which the profile was measured The coverage domain consists of a series of time instants at which values are recorded 03 Feb 2007 30 Climate Science Modelling Language Version 2 5 3 3 TrajectoryFeature The TrajectoryFeature provides a measurement along a discrete path in time and space cd TrajectoryFeature ff 4 implement I realize parameter ReferenceableGrid ObjectType Domain geometries TrajectoryDomain Figure 29 CSML TrajectoryFeature UML model There are no intrinsic attributes of the feature type but its associated coverage is defined over a TrajectoryDomain a one dimensional irregular grid embedded within a 2 3 or 4 d compound spatiotemporal coordinate reference system Figure 25 Note the reason for using a subclass of ReferenceableGrid for the domain rather than simply using the gml MultiPointCoverage is that the former supports full spatiotemporal geometry 03 Feb 2007 31 Climate Science Modelling Language Version 2 5 3 4 PointCollectionFeature A PointCollectionFeature is a collection of distributed single datum measurements
10. and International Oceanographic Commission IOC 1 1 5 Geography Markup Language GML GML viii provides reference XML schemas for a range of conceptual building blocks from other ISO standards e g for geometry and topology x spatial xi and temporal xii reference systems coverage and gridded data xiii etc While GML is a large specification its purpose is often misunderstood GML is an XML grammar written in XML Schema for the description of application schemas as well as the transport and storage of geographic information viii The specification notes that f ew applications will require the full range of capabilities described by the GML Schema The intention with GML is that its schema constructs should be used as building blocks to provide canonical encodings for feature types designed within a particular application domain While GML elements may be used in arbitrary XML documents the main purpose is to encode datasets according to an application schema A valid GML instance document may contain 03 Feb 2007 5 Climate Science Modelling Language Version 2 feature instances or collections dictionaries of coordinate reference systems or units of measure etc or collections of topological objects 1 1 6 The model driven approach The ISO framework implements a model driven approach to data encoding Feature types and datasets are first modelled at a conceptual level usi
11. at a particular time cd PointCollectionFeature Pa parameter Figure 30 CSML PointCollectionFeature UML model The sole attribute is e time optional the time at which the collection of measurements was taken The associated coverage provides the values at the set of measurement locations and is exactly an ISO 19123 CV_DiscretePointCoverage with gml MultiPointCoverage used for encoding 03 Feb 2007 32 Climate Science Modelling Language Version 2 5 3 5 ProfileFeature A ProfileFeature provides a single profile of some parameter along a vertical line in space cd ProfileFeature E Y realize Y implement 1 parameter Figure 31 CSML ProfileFeature UML model The attributes of this feature type are e location optional the base horizontal location from which the profile measurements were taken e time optional the nominal time at which the profile measurements were made The associated coverage provides values over the set of vertical levels A CSML ProfileCoverage is used which is simply an ISO 19123 CV_DiscretePointCoverage gml MultiPointCoverage with its domain restricted to a vertical array of points 03 Feb 2007 33 Climate Science Modelling Language Version 2 5 3 6 ProfileSeriesFeature A ProfileSeriesFeature represents a time series of profiles on fixed vertical levels at a fixed location cd ProfileSeriesFeatur
12. gridPoints GridPointDescription DataType GridOrdinateDescription coordAxisLabel string coordAxisValues SpatialOrTemporal PositionList gridAxesSpanned int 1 sequenceRule CV SequenceRule Union SpatialOrTemporalPositionList spatialPositionList GM_PointArray timePositionList Sequence lt TM_Instant gt This possibly needs to be a lt lt Type gt gt i e can have identity under GML rules E 2 4 10 identity is not possible for lt lt Union gt gt stereotypes So may need to break conventional GML rules and have this derive from AbstractGMLType in the gridOrdinate Set lt GridOrdinateDescription gt DataType GridPointDescription pointPositions GM_PointArray sequenceRule CV SequenceRul Since GML doesn t yet support mixed spatiotemporal positions in practice GridPointDescription can only be used for purely spatial grids Should GM_MultiPoint be used instead of GM_PointArray In principle we re just modelling the unordered collection of points that make up the domain of the grid however in order to assign them via CV_SequenceRule to the grid coordinates we need to assign an ordering and therefore GM_PointArray is used Figure 23 UML model for CSML ReferenceableGrid implementation 03 Feb 2007 24 Climate Science Modelling Language Version 2 5 CSML FEATURE TYPES The general model for all CSML feature
13. gt float lt numericType gt lt expression gt 0 5 50000 lt expression gt lt ArrayGenerator gt Figure 42 XML encoding example for ArrayGenerator TBD Need to define precise syntax and semantics of expression Perhaps based on simple MATLAB like multi d array expressions NB There are use cases where a parametrised expression is needed with the parameters coming from external storage e g model sigma levels defined by coefficients in a file 6 1 4 FileExtract Numeric values may be defined in file based storage The FileExtract and its subclasses are used for this purpose The following attribute is defined e fileName a pathname to the file The class is subclassed for NASA Ames netCDF GRIB and CDML files 6 1 4 1 NASAAmesExtract A NASAAmesExtract is used where data is being extracted from a NASA Ames format file The following attributes provide the minimal information required to identify the data to be extracted e variableName the name of the variable in the NASA Ames file e index there is no requirement for NASA Ames variable names to be unique In the event of duplication the index attribute allows a specific instance to be identified An example is given in Figure 43 lt NASAAmesExtract gt lt arraySize gt 526 lt arraySize gt lt numericType gt double lt numericType gt lt fileName gt data BADC macehead mh960607 asv lt fileName gt lt variableName gt coefficient a1 lt variableName gt lt NAS
14. phenomenonDictionary Dictionary 0 1 uomDictionary Dictionary 0 1 featureMember da FeatureType CSMLFeatureMember Figure 9 CSML FeatureCollection The FeatureCollection contains optional local definitions of units reference systems and phenomena as well as a collection of feature instances Since a FeatureCollection also derives from the gml AbstractFeatureType it inherits the following standard object attributes id a handle for the feature collection within the CSML document metaDataProperty may be used to link to a metadata record describing the feature collection description a text description of the feature collection identifier an identifier unique within the application domain to be used in references to the feature collection together with a mandatory authority code name a descriptive label for the feature collection with optional authority boundedBy a bounding envelope for the spatiotemporal extent of the feature collection An example skeleton XML encoding is outlined in Figure 10 CSMLFeatureCollection gml id FeatureCollection gt lt gml description gt Test CSML feature collection lt gml description gt lt gml identifier codeSpace http ndg nerc ac uk gt FC000000001 lt gml identifier gt 03 Feb 2007 16 Climate Science Modelling Language Version 2 lt gml name gt NDG Feature Collection lt gml name gt lt gml boundedBy gt lt gml EnvelopeWithTimePeriod srsName
15. points in a defined sequence order it is repeated for each axis of the coordinate system Furthermore if these coordinate values are uniform along one or more axes of the grid they do not need to be repeated over those grid axes Thus for the common case where a grid is aligned with the coordinate system axes but has non equally spaced grid point locations the coordinate values of grid points need only be specified along relevant grid axes and not over all grid points csml GridOrdinateDescription is defined as follows lt element name GridOrdinateDescription type csml GridOrdinateDescriptionType substitutionGroup gml AbstractObject gt lt complexType name GridOrdinateDescriptionType gt lt annotation gt lt documentation gt GridOrdinateDescription defines grid point locations over entire Grid for a single spatial or temporal coordinate axis lt documentation gt lt annotation gt lt sequence gt lt element name coordAxisLabel type NCName gt lt element name coordAxisValues type csml SpatialOrTemporalPositionListPropertyType gt lt element name gridAxesSpanned type gml NCNameList gt 03 Feb 2007 56 Climate Science Modelling Language Version 2 lt element name sequenceRule type gml SequenceRuleType gt lt sequence gt lt complexType gt lt complexType name GridOrdinateDescriptionPropertyType gt lt sequence gt lt element ref csml GridOrdinateDescription gt lt sequenc
16. urn EPSG geographicCRS 4979 gt lt gml lowerCorner gt 10 15 0 lt gml lowerCorner gt lt gml upperCorner gt 30 65 5000 lt gml upperCorner gt lt gml timePosition gt 1998 01 01 lt gml timePosition gt lt gml timePosition gt 2003 12 31 lt gml timePosition gt lt gml EnvelopeWithTimePeriod gt lt gml boundedBy gt lt featureMember gt lt feature instance gt lt featureMember gt lt featureMember gt lt another feature instance gt lt featureMember gt lt CSMLFeatureCollection gt Figure 10 Example skeleton XML encoding of CSML feature collection The local dictionaries for reference systems phenomena and units of measure are each structured as GML dictionaries as detailed in section 3 4 The collection of feature instances follows the standard GML mechanism viii 9 1 10 by defining the featureMember association to an AbstractFeatureMember 3 2 CSML StorageDescriptor GML provides two mechanisms for defining property content either inline or by reference via xlink see viii 7 2 3 CSML exploits the by reference device together with a speculative pattern on the use of xlink to assert that property content is derived from legacy storage However there is not generally a direct mapping between storage data models e g netCDF or GRIB files or relational tables and the conceptual feature types of CSML thus an additional model is needed for defining blocks of content paramet
17. AAmesExtract gt Figure 43 Encoding for NASAAmesExtract 03 Feb 2007 44 Climate Science Modelling Language Version 2 6 1 4 2 NetCDFExtract Only a variable name attribute is required in addition to the file name to identify an extract of data from a netCDF file e variableName the netCDF variable defining the contents of this numerical array An example is shown in Figure 44 NetCDFExtract gml id feat04azimuth gt lt arraySize gt 10000 lt arraySize gt lt fileName gt radar_data nc lt fileName gt lt variableName gt az lt variableName gt lt NetCDFExtract gt Figure 44 Encoding of NetCDFExtract 6 1 4 3 GRIBExtract The GRIBExtract class represents data extracted from a GRIB format file In order to uniquely identify the data required the following parameters are used e parameterCode the GRIB parameter code for the GRIB record to be extracted e recordNumber since a GRIB file can contain any number of records of the same parameter the specific record number may be indicated e fileOffset as an alternative to specifying the record number an explicit offset within the file to the start of the required GRIB record may be specified this avoids having to step through the file over earlier records until the required record is found An XML example is shown in Figure 45 lt GRIBExtract gt lt arraySize gt 320 160 lt arraySize gt lt numericT ype gt double lt numericT ype gt lt fileName gt e40 gg
18. Climate Science Modelling Language Version 2 CLIMATE SCIENCE MODELLING LANGUAGE VERSION 2 USER S MANUAL 03 Feb 2007 03 Feb 2007 Climate Science Modelling Language Version 2 TABLE OF CONTENTS Table ot Contents asa aerea lean nada Document Change Tog oed teta aeta iena Te Introduction RR raro e eee std coun ieu eig deese tete eet E ee ERE LP seeds 1 1 Standards based data modelling o oa 1 1 1 Domain Reference Model corona eerte cnn nrcnnn cons ti Be at res 3 NN LAS Application schenid pi a LIA Governance Issues ill aaa ai 1 1 5 Geography Markup Language GML 5e dia ea 1 1 6 The modelsdriven approach as ustioni 1 2 An interoperability model for legacy dat 1 3 Feature type principles for the climate sciences sssscsssssssssrssssssssssseseseseeeeeeeseserereres 1 9 1 gt dente data types oce ean end lid 1 3 2 Soft typing on phenomenon A 1 39 93 CONV ENON GE portrayal ico 1 4 The Observations and Measurements pattern sss 2 CSML v2 modelling principles and changes from CSML v1 ii 11 2 1 More explicitfeature types uenerat tomi uta ticis E Nis t eee 11 2 2 Observations and Measurements pattern s ra ieri 11 2 3 Behaviour of feature types the processing affordance pattern 12 2 4 Dataset Str cture dl ese ee a a coc o a dea o es 14 95 SCGSNIEDatasetziss cete tnim aria dan his 16 3 1 CSME
19. E E z ge 100 ae 100 E y 20 8 LATITUDE 3 wo c Q a wa 100 DE 100 E LONGITUDE Figure 47 Logically global data stored in separate physical files The xlink specification describes two models for linking an extended xlink and a simple xlink These are illustrated schematically in Figure 48 and Figure 49 extended xlink role title P 7 0 remote resource arcrole title ocal resource D 8 show role href title role label rtitlel Figure 48 Extended xlink 03 Feb 2007 47 Climate Science Modelling Language Version 2 simple xlink arc arcrole show Figure 49 Simple xlink An extended xlink enables multiple resources to be logically linked together with numerous metadata assertions concerning the nature of the resources and the links One model might have been top use such an extended xlink to perform the kinds of multi file aggregations provided by the CSML StorageDescriptor However it is unlikely that the arc traversal rules are sufficiently flexible and it seems easiest to manage aggregation parameterised reading of data files etc in a separate schema and define a single clean use of xlink for linking to it Thus we focus on the smaller problem of using a simple xlink to assert that logical content within a GML instance is encapsulated in a CSML ArrayDescriptor The elements of a simple xlink are as follows Figure 49 e href must specify a U
20. RI that resolves to a remote resource e role describes the meaning of the remote resource in the context of the link e title describes the meaning of the remote resource in a human readable fashion e arcrole describes the meaning of the link from the local resource GML property element to the remote resource corresponds to the RDF notion of a property starting resource HAS arc role ending resource e show used to communicate the desired presentation of the remote resource on traversal from the starting resource may take one of the values new replace embed other none 6 2 2 Use of xlink in CSML The pattern for xlink use in CSML exploits several of the available xlink attributes and is illustrated in Figure 50 03 Feb 2007 48 Climate Science Modelling Language Version 2 lt someGMLElement xlink arcrole hasRemoteContentEmbeddedAt localXpath xlink href storageDescriptor portion xlink role storageSchemaldentifier xlink show embed gt Figure 50 xlink pattern used in CSML The href attribute points to a portion of a storage artefact it could take any of several forms e g e netCDFFile variable for identifying an individual variable within a netCDF file e RDBMS SQLQuery for performing a SQL query against a relational source e GRIBFile recordNum for identifying a particular record in a GRIB file e CSMLStorageDescriptor arrayID for identifying a partic
21. al determinant of the scientific uses to which they may be put Moreover the properties of the instruments used to generate data themselves place constraints on their interpretation e g as regards accuracy precision calibration required post processing etc These two factors the scientific utility of a sampling regime and the limitations of an observing process lead to a natural scientifically important classification of data types along these axes Quite often the two are highly correlated certain instruments generate certain samplings and so scientific communities of practice adopt more abstract conceptual information classes that nevertheless reflect artefacts of sampling or instrument type This is particularly evident in the climate sciences where broad information classes based on measurement set geometry and topology have almost universal acceptance The following examples are illustrative The US National Oceanographic and Atmospheric Administration NOAA is developing a plan for a Global Earth Observing Integrated Data Environment GEO IDE to integrate measurements data and products and create interoperability across data management systems In the GEO IDE Concept of Operations https www nosc noaa gov dmc docs NOAA_ GEO IDE_CONOPS v3 3 pdf the following structural data types are defined Grids Moving sensor multidimensional fields Time series Profiles Trajectories Geospatial Framework Data Point Data Meta
22. as1992010100rsn grb lt fileName gt lt parameterCode gt 203 lt parameterCode gt lt recordNumber gt 5 lt recordNumber gt lt fileOffset gt 289412 lt fileOffset gt lt GRIBExtract gt Figure 45 XML encoding for GRIBExtract TBD Need to think about and say something about thinned grids etc Initially probably user application interpolates onto whatever grid size specified in arraySize 6 1 4 4 CDMLExtract Conceptually this is modelled the same as a netCDF file Only a variable name attribute is required in addition to the file name to identify an extract of data from a file set described through CDML e variableName the CDML variable defining the contents of this numerical array An example is shown in Figure 44 lt CDMLExtract gml id feat10gridtemp gt lt arraySize gt 360 180 10000 lt arraySize gt lt fileName gt era40 cdmi lt fileName gt 03 Feb 2007 45 Climate Science Modelling Language Version 2 lt variableName gt temperature lt variableName gt lt CDMLExtract gt Figure 46 Encoding of CDMLExtract 6 1 5 AggregatedArray The composite pattern is applied so that an array descriptor may be an aggregation of other array descriptors Arrays may be aggregated along either an existing dimension thus maintaining the dimensionality of the arrays or along a new dimension thus creating an n 1 dimensional array from n dimensional arrays The following properties are used e aggType a
23. asses 5 3 CSML Feature Types We now consider in turn the respective CSML feature types 03 Feb 2007 Climate Science Modelling Language Version 2 5 3 1 PointFeature The CSML PointFeature represents a single point measurement at a fixed position in space and optionally time and is modelled as shown in Figure 27 cd PointFeature Y CV DiscreteCoverage Discrete Coverages CV_DiscretePointCoverage find DirectPosition Integer Sequence lt CV_PointValuePair gt list Set lt CV_PointValuePair gt locate DirectPosition Set lt CV_PointValuePair gt implement parameter Need to separate out time from coverage domain as GML does not allow compound spatiotemporal position Figure 27 CSML PointFeature UML model The attributes are e location spatial location of the point measurement e time optional time of the point measurement The coverage domain consists of the single point location of the measurement 03 Feb 2007 29 Climate Science Modelling Language Version 2 5 3 2 PointSeriesFeature The CSML PointSeriesFeature represents a time series of single datum measurements at a fixed location in space cd PointSeriesFeature Fa A Uu implement em realize 1 parameter TM_Conplex EM Need efficient implementation of ObjectType Sequence TM Instant some kind Domain geometries TimeSeries of TimePositionList NB O
24. character string indicating aggregation along either an existing or new array dimension e aggIndex the dimension index along which aggregation is performed For example two 100x200 arrays may be aggregated along the existing index 1 to produce a 200x200 array or along the existing index 2 to produce a 100x400 array Aggregation along a new dimension 1 would create a 2x100x200 array along a new dimension 2 would create a 100x2x200 array etc 6 2 xlink pattern for linking stored data 6 2 1 Introduction to xlink A common pattern with file based data and part of the motivation for CSML is that semantic information structures of interest often need to be logically assembled within and across files The structures of interest or feature types under the ISO framework don t necessarily correspond directly with the data models or layouts within files What is required is a different view onto the data than that provided by existing file structures Note that this type of integration is provided implicitly in the relational model queries can select and join data across tables in any way required CSML starts by asking what the information structures of interest are with no notice taken of the storage mechanisms These information structures are formalised as feature types and may be represented as GML instances However content typically numerical within these feature instances is logica
25. data The ESRI ArcMarine Data Model for marine data includes classes like Instant Location Series Time Series Profile Line Track Sounding Survey Ir Regularly Interpolated Surfaces Mesh Volume etc File formats such as netCDF and NASA Ames utilise data models that reflect these structures e g netCDF four dimensional gridded lat lon height time variables or NASA Ames time series at a point Based on this observation CSML feature types are classified primarily around geometric and topologic structure and not the semantics of the observable or measurand This is consistent with the governance principle of Atkinson It would for example be outside the scope of CSML to define highly specialised feature types for universal exchange of met observations SYNOPs METARs etc The definition of such specialised feature types is rightly the domain of international organisations such as the WMO It is expected however that transformations would be possible from such specialised feature types to those of more general ambition defined here The CSML feature types do not carry any explicit topologic descriptions at present However GML provides rich schemas for describing topology a requirement may arise in the future to add this information to CSML 03 Feb 2007 8 Climate Science Modelling Language Version 2 1 3 2 Soft typing on phenomenon If two features are structurally identical except for the physical phenom
26. dentifier and optional name An example XML encoding is shown in Figure 13 this may provide the immediate content of a gml dictionaryEntry 03 Feb 2007 18 Climate Science Modelling Language Version 2 lt swe Phenomenon gml id rainfall gt lt gml description gt Liquid precipitation measured with raingauge lt gml description gt lt gml identifier codeSpace http ndg nerc ac uk gt gauge_rainfall lt gml identifier gt lt gml name gt rainfall lt gml name gt lt swe Phenomenon gt Figure 13 XML encoding of Phenomenon 3 4 1 2 CompositePhenomenon A composite phenomenon may be defined for example vector winds Each component is itself a Phenomenon Example XML encodings may be found in xvii 3 4 1 3 ConstrainedPhenomenon A phenomenon with multiple components derived by applying constraints to some base phenomenon may be characterised as a ConstrainedPhenomenon For example multi spectral radiance bands apply wavelength constraints to a base radiance phenomenon particle size distributions are classified by bands of particle size range Example XML encodings may be found in xvii 3 4 2 Unit definitions Normally units defined by external authorities are used see section XXX for an example encoding of the udunits system of units often used in the atmospheric sciences If local units need to be defined the GML units schema is used viii 17 2 An example XML encoding is shown in Figure 14 and may provid
27. e 5 implement ReferenceableGrid parameter ObjectType Domain geometries ProfileSeriesDomain ProfileSeriesDomain is 2 d z and t Figure 32 CSML ProfileSeriesFeature UML model The feature type has a single attribute e location optional the horizontal location at which the profiles were measured The profile values are provided as a gridded coverage ProfileSeriesCoverage over a two dimensional height time spatiotemporal domain ProfileSeriesDomain specialising ReferenceableGrid 03 Feb 2007 34 Climate Science Modelling Language Version 2 5 3 7 RaggedProfileSeriesFeature A RaggedProfileSeriesFeature is a time series of unequal length profiles but on fixed vertical levels at a fixed location cd RaggedProfileSeriesFeature E implement realize 7 ReferenceableGrid ObjectT ype Domain geometries parameter ProfileSeriesDomain ProfileSeriesDomain is 2 d z and t Figure 33 CSML RaggedProfileSeriesFeature UML model There are two attributes e location optional the horizontal location at which the profiles were measured e profileLength the number of valid measurements per profile for the series The measured profile values are provided through a ProfileSeriesCoverage but where values at missing vertical levels on each profile are ignored It is assumed implicitly that these missing values occur at the extreme end of t
28. e gt lt attributeGroup ref gml OwnershipAttributeGroup gt lt complexType gt The element csml coordAxisLabel names the coordinate system axis for which grid point locations are being defined It should be consistent with the axis labels used for the CRS associated through the gml srsName attribute of the parent csml ReferenceableGrid csml coordAxisValues lists grid point locations for the relevant coordinate system axis Both spatial and temporal coordinate system axes are supported The element csml gridAxesSpanned lists those grid axes along which this coordinate varies and for which grid point locations are being prescribed It will not normally include any grid axes along which all grid points have the same value for the coordinate being defined EXAMPLE 3 Consider a two dimensional grid with axes x y aligned with the longitude and latitude axes of the associated coordinate system Then the longitude coordinate varies only along the x grid axis and the latitude coordinate varies only along the y grid axis The element csml sequenceRule specifies the order in which the coordinate values are being specified over the grid axes spanned EXAMPLE 4 The csml ReferenceableGrid of EXAMPLE 1 may be encoded using csml GridOrdinateDescription as follows gml ReferenceableGrid gml id ID001 srsName urn ogc def crs EPSG 6 6 4326 dimension 2 gt lt gml limits gt lt gml GridEnvelope gt lt gml low gt 0 0 lt gml low gt lt gml h
29. e the content for a gml dictionaryEntry element gml UnitDefinition gml id psu gt gml description Conventional practical salinity units lt gml description gt lt gml identifier codeSpace http ndg nerc ac uk units gt practical_salinity_units lt gml identifier gt lt gml name gt practical salinity units lt gml name gt lt gml quantityType gt sea water salinity lt gml quantityType gt lt gml catalogSymbol codeSpace http ndg nerc ac uk units gt psu lt gml catalogSymbol gt lt gml UnitDefinition gt Figure 14 XML encoding of unit definition 3 4 3 Reference system definitions For defining coordinate reference systems the schemas of GML chapter 13 spatial based on xi and 15 temporal based on xii are used and should be consulted for details Briefly a coordinate reference system is defined by both a coordinate system and a datum Figure 15 Coordinate reference system 0 Coordinate system Figure 15 Conceptual model for coordinate reference system taken from ISO 19111 A coordinate system is defined by an ordered set of axes including their directions and units A datum provides the reference for the axes A number of coordinate system subclasses are 03 Feb 2007 19 Climate Science Modelling Language Version 2 specified by GML for instance geographic horizontal latitude longitude projected for map projections vertical and engineering for local application e g relative to a mo
30. eSeriesFeature RaggedProfileSeriesFeature SectionFeature RaggedSectionFeature Scanning RadarFeature GridFeature GridSeriesFeature SwathFeature 03 Feb 2007 Description Single point measurement Time series of single datum measurements at a fixed location in space Measurement along a discrete path in time and space Collection of distributed single datum measurements at a particular time Single profile of some parameter along a vertical line in space Time series of profiles on fixed vertical levels at a fixed location Time series of unequal length profiles but on fixed vertical levels at a fixed location Series of profiles from positions along a trajectory in time and space Series of profiles of unequal length along a trajectory in time and space Backscatter profiles along a look direction at fixed elevation but rotating in azimuth Single time snapshot of a gridded field Time series of gridded parameter fields Two dimensional grid of data along a satellite ground path Example raingauge measurement tidegauge rainfall timeseries surface salinity along a ship s cruise track atmospheric aerosols along an aircraft s flight path 2m temperatures measured at weather stations across the UK at 0600z wind sounding XBT CTD radiosonde vertical radar timeseries thermistor chain timeseries repeat daily balloon soundings of atmospheric temperature from the same location shi
31. eableGrid structure for the domain geometry 03 Feb 2007 39 Climate Science Modelling Language Version 2 5 3 12 GridSeriesFeature A GridSeriesFeature represents a time series of gridded parameter fields cd GridSeriesFeature ps implement ReferenceableGrid parameter ObjectType Domain geometries GridSeriesDomain Figure 38 CSML GridSeriesFeature UML model The feature type has no particular attributes The gridded time series of values are provided through a three or four dimensional gridded coverage under an associated spatiotemporal compound coordinate reference system Figure 25 03 Feb 2007 40 Climate Science Modelling Language Version 2 5 3 13 SwathFeature The CSML SwathFeature represents a two dimensional grid of data along a satellite ground path cd SwathFeature Se E implement realize Y Y Should have bounding polygon though not implemented in GML Perhaps should restrict associated coverage to a two dimensional subclass of ReferenceableGrid Figure 39 CSML SwathFeature UML model The feature type attributes are e eqCrossLon optional the equator crossing longitude for the satellite pass e eqCrossTime optional the equator crossing time for the satellite pass The observed swath values are provided through a two dimensional gridded coverage over the earths surface
32. el v Andrew Woolf Bryan Lawrence Jeremy Tandy Keiran Millard Dominc Lowe Sam Pepler 2006 Feature types as an integration bridge in the climate sciences AGU Fall Meeting San Diego Dec 2006 Eos Trans AGU 87 52 Fall Meet Suppl Abstract IN53C 02 vi ISO 19109 Geographic information Rules for application schema vii ISO 19110 Geographic information Methodology for feature cataloguing viii ISO 19136 Geographic information Geography Markup Language OGC GML version 3 1 1 document number 03 105r1 online http portal opengeospatial org files artifact_id 4700 31 January 2007 ix Atkinson R 2004 Next steps to interoperability Mechanisms for semantic interoperability EOGEO Workshop University College London 23 25 June 2004 Online http y eogeo org files eogeo2004 eogeo 2004 full atkinson ppt 31 January 2007 x ISO 19107 Geographic information Spatial schema xi ISO 19111 Geographic information Spatial referencing by coordinates xii ISO 19108 Geographic information Temporal schema xiii ISO 19123 Geographic information Schema for coverage geometry and functions xiv ISO 19103 Geographic information Conceptual schema language xv ISO 19118 Geographic information Encoding xvi UK MetOffice 2006 OGC Web Services and GML Modelling for Operational Meteorology Communiqu
33. emType gml TimePositionUnion gt lt simpleType gt Figure 17 CSML TimeValueList By direct analogy with gml TimePositionType the CSML TimePositionListType Figure 18 supplements the TimeValueList with frame and calendar attributes to support multiple time coordinate systems lt complexType name TimePositionListT ype gt lt annotation gt lt documentation gt By direct analogy with gml TimePositionType adds attributes to csml TimeValueList to support multiple time coordinate systems see GML 3 2 sect 15 2 2 7 lt documentation gt lt annotation gt lt simpleContent gt lt extension base csml TimeValueList gt lt attribute name frame type anyURI default ISO 8601 gt lt attribute name calendarEraName type string gt lt attribute name indeterminatePosition type gml TimelndeterminateValueType gt lt extension gt lt simpleContent gt lt complexType gt Figure 18 CSML TimePositionListType Once more by analogy with gml timePosition a CSML element timePositionList is defined Figure 19 lt element name timePositionList type csml TimePositionListType gt lt annotation gt lt documentation gt By direct analogy with gml timePosition creates a list version of the same see GML 3 2 sect 15 2 2 7 lt documentation gt lt annotation gt lt element gt Figure 19 CSML timePositionList An application of these definitions is the CSML TimeSeries object Figure 20 03 Feb 2007 21
34. ence These classes may be leveraged to build intelligent services for data subsetting aggregation processing etc As well CSML provide a wrapper mechanism to encapsulate legacy file based data exposing them instead through the conceptual view The motivation and context to CSML has been given in i ii Some key elements are reviewed below 1 1 Standards based data modelling An emerging series of international standards for geospatial data metadata and services iii provides a timely basis for meeting the CSML data integration requirements ii The series comprising some 40 standards is being developed by Technical Committee 211 Geographic Information and Geomatics of the International Organisation for Standardisation ISO 1 1 1 Domain Reference Model The overall scope of these standards is outlined in ISO 19101 iv which introduces the Domain Reference Model an abstract information architecture for geospatial data infrastructures At the core of the model is a geospatial Dataset A Dataset contains Feature instances see section 1 1 2 below and related objects and is described by Metadata Geographic information services operate on a Dataset while the logical structure and semantic content of a Dataset is described through an Application schema see section 1 1 3 below 1 1 2 Features A cornerstone of CSML is to use the feature model as its key to integratio
35. enon of interest temperature salinity wind vector humidity etc then they are modelled in CSML as the same feature type For example both a vertical wind profile and an atmospheric temperature sounding have similar characteristics in terms of attributes and data handling operations that may be performed differing primarily in the distinguishing physical parameter vector wind vs temperature Their representations are collapsed in CSML into the same feature type This principle soft typing on phenomenon has been identified as appropriate for GML modelling of coverage type data in operational meteorology xvi 1 3 3 Conventional portrayal Most climate science data has a conventional portrayal used by practitioners e g model output is typically displayed as shaded 2 d slices an atmospheric sounding as a line graph against height in the vertical a marine temperature section as a 2 d contoured field against depth and ship track distance etc A workable minimum granularity for CSML feature types is determined by applying a discriminant of sensible plotting there should be sufficient detail within a feature type and sufficient difference between feature types to enable in principle unsupervised rendering in the conventional manner This criterion is somewhat loose and it remains to be seen in practice the extent to which it is satisfied with the feature types chosen In that sense the principle may play a more im
36. ents model from xvii DataType TypedValue AnyDefinition ObjectT ype Phenomenon property ScopedName value Any AnyDefinition identifier ScopedName base name GenericName 0 remarks CharacterString 0 1 SI 1 component ObjectType ObjectType ConstrainedPhenomenon CompoundPhenomenon otherConstraint CharacterString 0 singleConstraint TypedValue 0 dimension Integer ObjectType CompositePhenomenon ObjectType PhenomenonSeries constraintList Sequence lt TypedValue gt 1 otherConstraint CharacterString 0 Figure 5 The O amp M Phenomenon model from xvii 03 Feb 2007 10 Climate Science Modelling Language Version 2 2 CSML V2 MODELLING PRINCIPLES AND CHANGES FROM CSML V1 Version Two of CSML includes a number of significant improvements over Version One xviii xix These are outlined here 2 1 More explicit feature types CSML v1 used a composite domain pattern to separate the feature type geometry into a reference component and a complement For example a ship s cruise track provides a reference geometry from which CTD measurements are taken along a complementary vertical geometry down through the water column In addition the reference geometry was overloaded in CSML v1 with some sophisticated heuristics required to infer the information class For ins
37. ependent of storage details an interoperable skeleton with 2 amechanism for mapping stored file based data into feature instances to provide the content adding digital flesh to the conceptual bones 10111001001011 Conceptual skeleton 01010001001010 111010111100 1110010101100 01010100100101 00101110110101 00110111010010 10111001011010 10000101111101 11001010101001 01010111010101 0111 010 Storage md 11010101110101 mapping Figure 3 The CSML interoperability model for legacy data This two component model for interoperability is represented in CSML through two schemas a GML application schema for feature instances and a storage descriptor schema for describing the logical extraction and aggregation of data from storage with the mapping between them being achieved through the use of xlink described in section 6 2 2 and usually does in this example 03 Feb 2007 7 Climate Science Modelling Language Version 2 1 3 Feature type principles for the climate sciences We examine here some of the guiding principles behind the choice of feature types in CSML 1 3 1 Scientific data types Physical processes occur in the natural world across a wide spectrum of spatial and temporal scales and considerable science informs the design of experimental sampling strategies It should be no surprise conversely that the geometry and topology of observation sets are a fundament
38. er 1 2 gt Linear lt csml sequenceRule gt lt csml GridOrdinateDescription gt lt csml gridOrdinate gt csml GridCoordinatesTable lt csml coordTransformTable gt lt csml ReferenceableGrid gt Figure 53 CSML ReferenceableGrid using GridOrdinateDescription for geolocation NOTE In this example the formatting of the coordinate values within the csml coordinateList is not relevant for XML processing NOTE In this example longitude coordinates of grid points are uniform along the y axis of the grid see Figure 8 and so the corresponding csml gridOrdinate needs only to specify values along the x axis i e the grid axis spanned is x Latitude values however vary along both grid axes and so are specified over both grid axes in the defined sequence order In order to support compound spatiotemporal coordinate reference systems coordinate values are specified using a cs SpatialOrTemporalPositionList element name SpatialOrTemporalPositionList type csml SpatialOrTemporalPositionListT ype substitutionGroup gml AbstractObject gt lt complexType name SpatialOrTemporalPositionListType gt lt annotation gt lt documentation gt SpatialOrTemporalPositionList allows efficient lists of either spatial or temporal positions lt documentation gt lt annotation gt lt choice gt lt element name coordinateList gt lt simpleType gt lt list temType double gt lt simpleType gt lt element gt
39. es in the coordinateList are stored in the lon variable of a netCDF file myfile nc Then the following application of xlink asserts this in CSML 6 Note that this is not conformant with the semantics of the URI specification which requires the fragment portion after the separator to be evaluated only after the entire resource has been retrieved In this case it provides merely a convenient syntax understood to be targeted at some application near the data that can interpret the fragment portion 03 Feb 2007 49 Climate Science Modelling Language Version 2 lt csml gridOrdinate gt lt csml GridOrdinateDescription gt lt csml coordAxisLabel gt Geodetic longitude lt csml coordAxisLabel gt lt csml coordAxisValues xlink arcrole http ndg nerc ac uk xlinkUsage insert SpatialOrT emporalPositionList coordinateList xlink href file myfile nc lon xlink role http ndg nerc ac uk fileFormat netcd xlink show embed gt lt csml SpatialOrTemporalPositionList gt lt csml coordinateList srsNamez WGS84 lt csml SpatialOrTemporalPositionList gt lt csml coordAxisValues gt lt csml gridAxesSpanned gt x lt csml gridAxesSpanned gt lt csml sequenceRule axisOrder 1 gt Linear lt csml sequenceRule gt lt csml GridOrdinateDescription gt lt csml gridOrdinate gt The arcrole asserts that the netCDF lon variable should be inserted at the relative XPath location SpatialOrTemporalPosit
40. fordance operations implement realize parameter ReferenceableGrid ObjectT ype Domain geometries ScanningRadarDomain Figure 36 CSML ScanningRadarFeature UML model There is one attribute for a ScanningRadarFeature e elevation optional the fixed elevation of the radar scanning beam The radar measured values are provided in a ScanningRadarCoverage This has a domain that is a two dimensional grid in a coordinate reference system with axes of azimuth and range Thus the coverage domain is modelled Figure 25 as a specialisation ScanningRadarDomain of a ReferenceableGrid that must be associated to such a coordinate reference system CSML provides the specialised AzimuthRangeCRSType for this purpose restricting an EngineeringCRS to consist of a polar coordinate system gml polarCS and a specialised engineering datum the CSML azimuthRangeDatum 03 Feb 2007 38 Climate Science Modelling Language Version 2 5 9 1 GridFeature A CSML GridFeature represents a single time snapshot of a gridded field cd GridFeature Y A implement parameter Figure 37 CSML GridFeature UML model The single attribute is e time the time of the gridded field The field values are provided as a coverage ReferenceableGridCoverage over an irregular grid of any dimension embedded within a coordinate space of any dimension It uses directly the Referenc
41. gage with the community concerned Various points of agreement must be established what are 1 the information objects that should be modelled as features 2 the precise definition of feature types i e their attributes associations and behaviours 3 common dictionaries e g for physical units coordinate references systems physical phenomena definitions etc and 4 maintenance procedures for agreed definitions Governance also is an important control for typing granularity of features ix A priori it is not always obvious to a designer of feature types how strongly typed they should be see Figure 1 In general the more specialised the feature types the greater will be the number required to capture the spectrum of information types used by the community weakly typed strongly typed SondeProfile AtmosphericTemperatureSounding instrument measuredParameter measuredParameter lt Measurement gt instrument RADIOSONDE lt instrument gt measuredParameter TEMPERATURE lt measuredParameter gt lt Measurement gt lt SondeProfile gt measuredParameter TEMPERATURE lt measuredParameter gt lt SondeProfile gt lt AtmosphericTemperatureSounding gt Figure 1 Typing granularity from ii Within the climate science community bodies that might be expected to hold a mandate for maintaining detailed Feature Type Catalogues include the UN agencies World Meteorological Organisation WMO
42. h an associated 2 physical parameter and the 3 value of this parameter as a CSML coverage Thus for example a CSML Grid Feature may be measuring the parameter temperature with the temperature values supplied though a gridded coverage Union procedure Procedure cd O amp M FeatureT ype observ ation Observ ation featureOfInterest observedProperty AnyDefinition parameter ObjectType phenomenon Phenomenon Figure 6 The Observations and Measurements view of CSML These three components then provide directly the O amp M feature of interest observed property and observation result respectively Not explicitly modelled in CSML is the O amp M procedure used to generate the result 2 3 Behaviour of feature types the processing affordance pattern A UK MetOffice sponsored workshop xvi on GML modelling for operational meteorology recognised that mere GML modelling and representation of data types omitted an important element of the General Feature Model the operations that may be performed on an object For instance a four dimensional timeseries of gridded NWP data supports an operation to extract from it a pseudo radiosonde observation This is easy enough to model conceptually 03 Feb 2007 12 Climate Science Modelling Language Version 2 e g through an operation extractRadiosonde on the UML feature class but is not represented in the GML serialisation
43. he profile in each case i e the seafloor end of a marine profile taken from the surface or the up most height levels for an atmospheric sounding from the earth The motivation for the use of a ProfileSeriesCoverage for this purpose is not cleanly conceptual but has a significant encoding efficiency benefit i e repeating vertical measurement locations don t need to be repeated in the encoding 4 An alternative approach could specify the start and end index rather than total profile length for each profile in the series 03 Feb 2007 35 Climate Science Modelling Language Version 2 5 3 8 SectionFeature A SectionFeature provides a series of profiles from positions along a trajectory in time and space cd SectionFeature implement 4 realize 4 ReferenceableGrid parameter ObjectType Domain geometries SectionDomain Figure 34 CSML SectionFeature UML model The following attributes are defined e stationLocations optional an array of locations along the trajectory at which profile measurements are taken e stationTimes optional the list of times at which the profiles were taken The values along the section are available in a CSML SectionCoverage with a domain that is a two dimensional grid embedded in three dimensional space and with one axis aligned vertically Figure 25 03 Feb 2007 36 Climate Science Modelling Language Version 2 5 3 9 RaggedSect
44. igh gt 7 4 lt gml high gt lt gml GridEnvelope gt lt gml limits gt lt gml axisLabels gt x y lt gml axisLabels gt lt csml coordTransformTable gt lt csml GridCoordinatesTable gt lt csml gridOrdinate gt lt csml GridOrdinateDescription gt lt csml coordAxisLabel gt Geodetic longitude lt csml coordAxisLabel gt lt csml coordAxisValues gt lt csml SpatialOrTemporalPositionList gt lt csml coordinateList gt 13 5 24 9 32 4 37 7 41 5 46 8 54 4 65 7 lt gml coordinateList gt lt csml SpatialOrTemporalPositionList gt lt sml coordAxisValues gt lt csml gridAxesSpanned gt x lt csml gridAxesSpanned gt lt csml sequenceRule axisOrder 1 gt Linear lt csml sequenceRule gt lt csml GridOrdinateDescription gt lt csml gridOrdinate gt lt csml gridOrdinate gt lt csml GridOrdinateDescription gt lt csml coordAxisLabel gt Geodetic latitude lt csml coordAxisLabel gt lt csml coordAxisValues gt lt csml SpatialOrTemporalPositionList gt lt csml coordinateList gt 53 1 48 7 46 2 44 7 43 9 43 3 43 1 44 0 46 2 43 2 41 5 40 6 40 2 40 0 40 3 41 7 37 1 36 1 35 6 35 5 35 7 36 0 37 1 39 5 30 4 30 2 30 4 30 7 31 1 32 0 33 8 37 2 03 Feb 2007 57 Climate Science Modelling Language Version 2 24 3 24 8 25 3 26 0 26 6 27 7 29 7 33 4 lt csml coordinateList gt lt csml SpatialOrTemporalPositionList gt lt csml coordAxisValues gt lt csml gridAxesSpanned gt x y lt csml gridAxesSpanned gt lt csml sequenceRule axisOrd
45. imension Positioning Valuation lt lt Type gt gt lt lt Type gt gt CV RectifiedGrid CV GridValuesMatrix origin DirectPosition Positioning values Sequencee lt Record gt sequencingRule CV SequenceRule startSequence CV GridCoordinates offsetVectors Sequence lt Vector gt coordConv g CV_GridCoordinate DirectPosition invCoordConvip DirectPosition CV_GridCoordinate CoordinateReferenceSystem lt lt Type gt gt CV_ReferenceableGrid coordTransform g CV_GridCoordinate DirectPosition lt lt Abstract gt gt invCoordTransform p DirectyPosition CV_GridCoordinate SC_CRS from Spatial Referencing by Coordinates Figure 22 ISO 19123 classes of quadrilateral grid geometry The text from this change proposal is reproduced in the Annex at section 10 of this manual but Figure 23 below shows the UML model for CSML s implementation Instance examples are given in Figure 52 and Figure 53 of the Annex 03 Feb 2007 23 Climate Science Modelling Language Version 2 cd ReferenceableGrid ObjectT ype ReferenceableGrid Grid id ID coordTransformTable GridCoodinatesT abl AxisName string 1 limits GridEnvelope zAbstractGeometry ssName anyURI AbstractGML description CharacterString 0 1 name GenericName 0 Union GridCoodinatesTable
46. ionFeature A RaggedSectionFeature is a series of profiles of unequal length along a trajectory in time and space cd RaggedSectionFeature E implement 1 4 realize 4 parameter ReferenceableGrid ObjectT ype Domain geometries SectionDomain Figure 35 CSML RaggedSectionFeature UML model It has the following attributes e stationLocations optional an array of locations along the trajectory at which profile measurements are taken e stationTimes optional the list of times at which the profiles were taken e profileLength the number of valid measurements per profile for the series The measured profile values along the section are provided through a SectionCoverage but where values at missing vertical levels on each profile are ignored It is assumed implicitly that these missing values occur at the extreme end of the profile in each case i e the seafloor end of a marine profile taken from the surface or the up most height levels for an atmospheric sounding from the earth 5 An alternative approach could specify the start and end index rather than total profile length for each profile in the series 03 Feb 2007 37 Climate Science Modelling Language Version 2 5 3 10 ScanningRadarFeature A ScanningRadarFeature provides backscatter profiles along a look direction at fixed elevation but rotating in azimuth cd ScanningRadarFeature Pi Need to add af
47. ionList coordinateList relative to the coordAxisValues start element Such an XPath mechanism is needed since not all GML properties allow the by reference pattern csml coordinateList here is one example The show attribute with its value of embed means that the file based content should logically be embedded within the CSML instance document 03 Feb 2007 50 Climate Science Modelling Language Version 2 7 TOOLING 03 Feb 2007 51 Climate Science Modelling Language Version 2 8 SCHEMAS 03 Feb 2007 52 Climate Science Modelling Language Version 2 9 EXAMPLES 03 Feb 2007 53 Climate Science Modelling Language Version 2 10 APPENDIX GML CHANGE REQUEST FOR REFERENCEABLEGRID 10 1 ReferenceableGrid A referenceable grid is associated with a transform between grid coordinates and coordinates in an external coordinate reference system Unlike a rectified grid this relationship cannot be characterised through an affine transformation It is instead provided in a table relating the grid points to coordinates in the external coordinate reference system The grid lines in the external coordinate reference system need not be straight or orthogonal and the grid cells may be of different shapes and sizes EXAMPLE 1 Figure 51 shows an example of a referenceable grid Figure 51 ReferenceableGrid example Two mechanisms are provided to specify the transformation table either listing
48. ions to the general modelling paradigm Figure 7 shows the CSML modelling of processing affordance through a UML type realised by a feature 03 Feb 2007 13 Climate Science Modelling Language Version 2 cd Abstract CSML Feature ve CV_Coverage Discrete Coverages CV_DiscreteCoverage locate DirectPosition Set lt CV_GeometryValuePair gt implement realize domainSet parameter Figure 7 Implementation of processing affordance in CSML through UML type Two other modelling points are worth noting from Figure 7 CSML defines specialised domain geometries for its respective coverages and the CSML coverage classes are logical implementations of the ISO 19123 CV_DiscreteCoverage coverage class hierarchy 2 4 Dataset structure As mentioned above section 1 2 CSML marries a conceptual features view of information with a mechanism for mapping onto this view legacy file based data In CSML v1 both components were part of the one schema and included together in a CSML i e GML instance document However the storage descriptor component cannot validly extend any semantic construct provided within GML there is nothing in GML concerned with data storage artefacts Thus in CSML v2 the CSML feature types and GML application schema are separated from the storage descriptor schema An instance of the CSML application schema is a valid GML document that may refer using an
49. lement gt gt ing the more abstract CV_DiscreteCoverage This should be regarded asa transtional state that will be revised once the fully a implement spatiotemporal domains enabled A S by ISO FDIS 19111 2006 E become integrated through the implement implement implement implement cimplement remainder of the ISO 19100 series Not clear whether GridSeriesCoverage and ProfileSeriesCoverage should be modelled as lt lt implement gt gt ing CV DiscreteGridPointCoverage or CV DiscreteCoverage In principle CV Grid ISO 19123 can be associated to any SC CRS defined by ISO 19111 Since ISO FDIS 19111 2006 E supports fully spatiotemporal CRS then the CV Grid should allow temporal axes And then both of these CSML coverage types are lt lt implement gt gt ations of CV DiscreteGridPointCoverage Howvere the same counter arguments apply here as for ProfileSeriesCoverage and TrajectoryCoverage with respect to CV DiscretePointCoverage vs CV DiscreteCoverage i e lack of GML support of ISO FDIS 19111 2006 E ISO 19107 implicit spatial assumption In any case for now leave asis since adopting a similar approach as ProfileSeriesCoverage TrajectoryCoverage here would mean rejecting the premise that ReferenceableGrid is an implementation of CV Grid and therefore csml ReferenceableGrid derives from gml Grid and this is a major step backwards Figure 26 CSML coverage cl
50. lly derived from files but may need to be extracted and aggregated in complex ways in order to map into the feature instance A simple example is illustrated in Figure 47 where a feature type might represent a global field of sea surface temperature but the data either side of the equator is stored in two separate physical files The CSML StorageDescriptor described above provides a mechanism for describing the logical extraction and aggregation of data across multiple files What is needed as well is a mechanism for asserting that a resulting such logical chunk of data logically provides the content for part of an XML feature instance Fortunately such a mechanism exists already although it is poorly tested best practice is far from resolved and its use for this purpose was almost certainly never envisaged in GML The XML Linking Language xlink xxii allows elements to be inserted into XML documents in order to create and describe links between resources It allows XML documents to assert linking relationships among more than two resources and associate metadata with a link GML explicitly supports the use of xlink in the by reference pattern for property values viii 7 2 3 1 the value of the property is available elsewhere and is identified by the value of an xlink href attribute on the property element 03 Feb 2007 46 Climate Science Modelling Language Version 2 80 N a Q E z LATITUD
51. n v Defined broadly as an abstraction of a real world phenomena a feature may represent any important aspect of a universe of discourse and may be characterised in terms of its attributes associations with other features and operations that may be performed the so called General Feature Model vi In essence features provide an object view of data and may occur as both types and instances Feature type definitions may be stored for re use in catalogues ISO 19110 vii Since features encapsulate important data semantics within communities of practice such Feature Type Catalogues may be regarded as semantics repositories within an overall information architecture Feature instances are the primary constituents of geospatial Datasets 1 1 3 Application schema While feature types define individual information classes a Dataset is described with an Application schema iv vi It defines the logical structure and semantic content of a dataset and specifies the allowable feature types that may be contained CSML is an application schema of the Geography Markup Language GML viii see section 1 1 5 below 1 1 4 Governance issues The integration framework outlined above aims to capture semantics of important community information types To be successful any attempt to apply this framework must 1 http www isotc211 org 03 Feb 2007 4 Climate Science Modelling Language Version 2 en
52. n ogc def crs EPSG 6 6 4326 dimension 2 gt lt gml limits gt lt gml GridEnvelope gt lt gml low gt 0 0 lt gml low gt lt gml high gt 7 4 lt gml high gt lt gml GridEnvelope gt lt gml limits gt lt gml axisLabels gt x y lt gml axisLabels gt lt csml coordTransformTable gt lt csml GridCoordinatesTable gt lt csml gridPoints gt lt csml GridPointDescription gt lt gml posList gt 13 5 53 1 24 948 7 32 446 2 37 7 44 7 41 543 9 46 8 43 3 54 443 1 65 7 44 0 13 546 2 24 943 2 32 441 5 37 740 6 41 540 2 46 840 0 54 440 3 65 7 41 7 13 5 37 1 24 936 1 32 435 6 37 735 5 41 535 7 46 836 0 54 437 1 65 7 39 5 13 5 30 4 24 9 30 2 32 4 30 4 37 7 30 7 41 531 1 46 8 32 0 54 433 8 65 7 37 2 13 5 24 3 24 9 24 8 32 4 25 3 37 726 0 41 5266 46 8 27 7 54 4 29 7 65 7 33 4 lt gml posList gt lt gml sequenceRule axisOrder 1 2 gt Linear lt gml sequenceRule gt lt csml GridPointDescription gt lt csml gridPoints gt lt csml GridCoordinatesTable gt lt csml coordTransformTable gt lt csml ReferenceableGrid gt Figure 52 CSML ReferenceableGrid using GridPointDescription for geolocation NOTE In this example the formatting of the grid point locations within the gml posList is for illustrative purposes only and not relevant for XML processing 10 3 GridOrdinateDescription GridOrdinateDescriptionType GridOrdinateDescriptionPropertyType A csml GridOrdinateDescription lists the values of a single coordinate system axis over the grid
53. ng a conceptual schema language UML xiv The conceptual UML model then provides an interoperable view of data independent of actual representation For canonical encoding and exchange an automated mapping to XML is defined see xv and Annexes E and F of GML viii Indeed apart from some historical quirks GML itself is little more than the programmatic XML realisation of UML conceptual models defined in other ISO standards CSML provides an additional mechanism for mapping file based data onto a GML instance as described next 1 2 An interoperability model for legacy data The ambition of CSML to provide standards based interoperable information models for the climate sciences is in tension with the reality of data management praxis in this domain very large volume often tera scale file based data in proprietary or ad hoc but efficient formats with a considerable legacy of existing often elaborate operational infrastructure built around them It is infeasible on numerous grounds to imagine warehousing existing data into a new interoperable XML representation CSML attempts to strike a middle ground Figure 2 and is proposed as a best practice approach for similar problem domains GML CSML Interoperability netCDF GRIB etc o Representation efficiency Figure 2 Interoperability vs efficiency in the climate sciences The goal of interoperability suggests the standards based approach described above
54. opertyType A csml GridPointDescription lists the location of grid points explicitly as a sequence of direct positions in an external coordinate reference system in a defined sequence order csml GridPointDescription is defined as follows lt element name GridPointDescription type csml GridPointDescriptionType substitutionGroup gml AbstractObject gt lt complexType name GridPointDescriptionType gt lt annotation gt lt documentation gt GridPointDescription defines grid point locations over entire Grid by listing direct positions in given sequence order lt documentation gt lt annotation gt lt sequence gt lt group ref gml geometricPositionListGroup gt lt element name sequenceRule type gml SequenceRuleType gt lt sequence gt lt complexType gt lt complexType name GridPointDescriptionPropertyType gt lt sequence gt lt element ref gml GridPointDescription gt lt sequence gt lt attributeGroup ref gml OwnershipAttributeGroup gt lt complexType gt 03 Feb 2007 55 Climate Science Modelling Language Version 2 The element group gml geometricPositionListGroup contributes a gml posList to the content model providing a list of direct positions for all grid point locations in the sequence order specified by gml sequenceRule EXAMPLE 2 The csml ReferenceableGrid of EXAMPLE 1 may be encoded using a csml GridPointDescription as follows csml ReferenceableGrid gml id ID001 srsName ur
55. or together into a CSML Dataset The structure was shown earlier in Figure 8 3 4 Local dictionaries As described in section 3 1 above a CSML FeatureCollection may include local definitions of reference systems phenomena and units of measure using the gml Dictionary structure viii 816 Figure 12 as the child of csml crsDictionary csml phenomenonDictionary or csml uomDictionary elements respectively Each of the three types of dictionary are described below The following standard properties are available for a GML Dictionary id description identifier name gml Dictionary gml id CSML Local CRS Dictionary gt lt gml identifier codeSpace http ndg nerc ac uk gt CRS0000001 lt gml identifier gt lt gml dictionaryEntry gt lt gml dictionaryEntry gt lt gml dictionaryEntry gt lt gml dictionaryEntry gt lt gml Dictionary gt Figure 12 XML structure of GML dictionary 3 4 1 Phenomenon CSML feature types are representations of a physical phenomenon temperature wind salinity etc The definition of physical phenomena is referred typically to external authorities for instance see section XXX for an example GML encoding of the CF standard name table widely used in atmospheric sciences However local definitions may be prescribed based on the O amp M conceptual model of Figure 5 3 4 1 1 Phenomenon A phenomenon definition is characterised by a local id optional description namespace qualified i
56. ositionList gt lt TimeSeries gt Figure 21 CSML TimeSeries example 4 2 CSML ReferenceableGrid ISO 19123 defines three classes of quadrilateral grid geometry a non geo referenced Grid CV_Grid a grid with regular spacing CV_RectifiedGrid and a grid with irregular spacing CV_ReferenceableGrid Figure 22 GML however provides implementations only of CV_Grid gml Grid and CV_RectifiedGrid gml RectifiedGrid The case of grid geometries with unequal spacing has no GML encoding mechanism However this type of geometry is crucial in the climate sciences the following is a non exhaustive indicative list of examples e weather models with an enhanced resolution over some region of interest 03 Feb 2007 22 Climate Science Modelling Language Version 2 e ocean models with displaced poles to avoid the meridional convergence singularity e boundary fit models e g for coastal dynamics or river flow e non rectified remote sensed imagery CSML provides an implementation of the ISO 19123 CV_ReferenceableGrid and this has been submitted to OGC as a GML change request in document number 06 160 xxi lt lt Type gt gt CV_Grid dimension Integer axisNames Sequence lt CharacterString gt extent CV_GridEnvelope dimension lt origin CRS theSC_CoordinateSystem dimension offsetVectors gt size dimension offsetVectors gt forAlI dimension self origin CRS 1heSC CoordinateSystem d
57. pborne ADCP marine CTD measurements along a ship s cruise track weather radar gridded analysis field numerical weather prediction model ocean general circulation model AVHRR satellite imagery 26 Climate Science Modelling Language Version 2 5 1 ReferenceableGrid subclasses The CSML ReferenceableGrid structure plays an important role in modelling the geometry of the feature types A number of the CSML coverage domain geometries derive from CSML ReferenceableGrid restricting on dimensionality of the grid or coordinate reference system or both Figure 25 illustrates the ReferenceableGrid subclasses used in CSML cd ReferenceableGrid subclasses q 2 d Grid 2 d Grid 2 d Azimth Range CRS 8 d spatial CRS Grid One grid axis aligned with CRS Z axis ObjectT ype ReferenceableGrid coordTransformT able GridCoodinatesT able Grid ObjectT ype AxisName string 1 ScanningRadarDomain limits GridEnvelope 3 LAbstractGeometry ObjectType vA i i srsName anyURI SectionDomain T zAbstractGML description CharacterString 0 1 id ID io name GenericName 0 Z SC_EngineeringCRi A X CRS AzimuthRangeCR 1 d Grid 2 3 or 4 d composite CRS 1 2 or 3 d spatial 1 d temporal ObjectType ProfileSeriesDomain SF Grae Ew 8 or 4 d compositeCRS 2 or 3 d spatial 1 d temporal 2 d Grid 2 d composi
58. portant role in evaluation than in design 1 4 The Observations and Measurements pattern The Open Geospatial Consortium s Observations and Measurements best practice paper xvii provides a conceptual model and encoding for observations and measurements Under this model an observation is an event whose result is an estimate of the value of some property of a feature of interest obtained using a specified procedure Figure 4 Each of the major classes in the model may be specialised for a particular application domain The observed property of an observation may be modelled using the O amp M Phenomenon taxonomy Figure 5 03 Feb 2007 9 Climate Science Modelling Language Version 2 precedingEvent m followingEvent m FeatureType DataT ype Event TypedValue eventParameter TypedValue 0 property ScopedName time TM_Object value Any Union Procedure procedureType ProcedureSystem procedureUse ProcedureEvent procedure AnyDefinition ObjectType generatedObservation Phenomenon FeatureType Observ ation 1 quality DQ_Element 0 1 Definition must be of a responsible CI ResponsibleParty 0 1 phenomenon that is a property result Any of the featureOfinterest observedProperty propertyValueProvider gatureOfInterest Anyldentifiable Object FeatureType AnyldentifiableFeature Figure 4 The Observations and Measurem
59. rically derived from one or more storage elements This is the CSML StorageDescriptor schema instantiated in an XML document logically separate from the CSML FeatureCollection but closely related to it through xlink references between the two Figure 8 The details of the StorageDescriptor are described in section 6 1 while the use of xlink is outlined in section 6 2 Figure 11 shows a skeleton XML encoding for the CSML StorageDescriptor lt CSMLStorageDescriptor gt lt descriptor gt 03 Feb 2007 17 Climate Science Modelling Language Version 2 lt descriptor gt lt descriptor gt lt descriptor gt lt CSMLStorageDescriptor gt Figure 11 Skeleton XML encoding for CSML StorageDescriptor 3 3 CSML Dataset wrapper The CSML FeatureCollection is a valid GML collection of features and can form the root of valid GML instance document On the other had the CSML StorageDescriptor does not inherit from any GML construct and may not form any part of a valid GML instance Logically the CSML FeatureCollection and StorageDescriptor are root elements of two separate XML documents However the two documents are in fact closely related the StorageDescriptor describes the construction from stored data of logical feature instances in the FeatureCollection From a maintenance perspective it is essential that they be tightly coupled A simple convenience schema is therefore defined which wraps a FeatureCollection and StorageDescript
60. s extracted from file based storage e AggregatedArray an aggregation of two or more arrays along an existing or new dimension In addition a numeric or regular expression transformation can be applied to any of the above as appropriate 6 1 1 ArrayDescriptor This is the abstract base class for all CSML numeric array descriptors The following attributes are defined and inherited by all concrete classes e arraySize a sequence of integers specifying the dimensions of the array being defined e uom units of measure This is required whenever the array descriptor is used for a coverage rangeSet when used for the domainSet the coordinate axis units are specified in the parent geometry object e numericType a string float double short int defining the numeric type to which the values should be cast in a user application e numericTransform an expression providing a mathematical transformation to be applied to the numeric values defined by this descriptor e regExpTransform a regular expression providing a textual transformation to be applied to the direct character based data defined by this descriptor e g where inline values are supplied or the file is ASCII encoded This is applied before any cast to a numerical type within the user application 6 1 2 InlineArray This class is used for specifying values as direct inline XML content The only attribute is e values a list of values any simple t
61. sientas cche 39 5 3 12 GridSeriesEeature inier eee ede sees Cte eee ir nee dactilares 40 5 3 13 Swath Ca ture i i tn CE D Ge ene Eod 41 0 Ele ICAO a M n 42 6 1 CSML 5totase Descriptor sacs eni peto DH a 42 611 AbstractArrayDesctiptot usto o erede tha dp tu tenet o ne e money 43 61 2 Inl eAIEAVenoeei OE II ope vi oii pee IR HR RH 43 6 1 3 PITA Generato lee 44 6 14 AbstractEileBxtract aet nive te eeclesie db 44 05 Aggregated Arta uten tex AAA M REIR UR ete vi QR 46 6 2 Msc a 46 o TOUR 51 B BXampless ti 52 9 Appendix GML Change request for ReferenceableGfid avion 54 9 1 ReferenceableGrid iiec titre eter tette rime aceite ite a deese ree nde 54 9 2 GridPointDescription GridPointDescriptionType GridPointDescriptionProperty DVDe ini alari 55 9 3 GridOrdinateDescription GridOrdinateDescriptionType GrdOrdinateDescHphonPropertyIype uil 56 References emassa tte e nete en a E d Da Ce eed re e eee die et dee hen Es 59 DOCUMENT CHANGE LOG Revision history Document version Contributors Date Changes 0 1 Andrew Woolf 2005 01 09 CSML Version One 0 2 Andrew Woolf CSML Version Two Dominic Lowe 03 Feb 2007 3 Climate Science Modelling Language Version 2 1 INTRODUCTION The Climate Science Modelling Language CSML provides a standards based semantic model and encoding for representing a range of conceptual information classes of relevance to climate sci
62. tance a ProfileSeries feature represented a series of profile measurements away from some reference geometry The reference geometry could be a single point with a series of angular look directions for a scanning radar or a series of time instants for a vertical sounding radar time series or a full trajectory in time and space for a marine section along a ship s cruise track In CSML v2 the six core feature types of CSML v1 have been refactored into a series of 13 more explicit feature types as per Table 1 In addition a Swath feature has been added Table 1 CSML feature type changes v1 to v2 CSML v1 feature type CSML v2 feature type Point Point PointSeries PointSeries Trajectory PointCollection Profile Profile ProfileSeries RaggedProfileSeries ProfileSeries Section RaggedSection ScanningRadar Grid Grid GridSeries GridSeries Swath 2 2 Observations and Measurements pattern CSML v1 used only the Phenomenon class of the O amp M model CSML v2 however is re factored to be fully compatible with the model and the infrastructure being developed around it e g web services including the Sensor Observation Service and instrument descriptions using SensorML 03 Feb 2007 11 Climate Science Modelling Language Version 2 The general O amp M pattern was described earlier in section 1 4 and Figure 4 It is applied in CSML by modelling the following three components Figure 6 1 a CSML feature type wit
63. te CRS 1 d spatial ObjectType 1 d temporal TrajectoryDomain CIS ObjectType ridSeriesDomain crs SC_CompoundCRS CRS SpatioTemporalCRS Crs Figure 25 ReferenceableGrid subclasses for distinct CSML coverage geometries 5 2 CSML coverage types As mentioned above CSML feature types are distinguished primarily on the geometry of their coverage domain for reasons discussed in section 1 3 1 Figure 26 illustrates the modelling of these coverages and shows the relationship to ISO 19123 coverage classes CSML coverages are regarded as implementations of the ISO coverage classes 03 Feb 2007 27 Climate Science Modelling Language Version 2 cd Coverage Types 7 domainElement collection 9 collection NB In principle the domains of both TrajectoryCoverage and rangeElement PointSeriesCoverage are gt sequences of GM_Pointsin a spatiotemporal CRS and since the CV_PointValuePair hasa GM_Point geometry should lt lt implement gt gt CV DiscretePointCoverage However it is only the new implement revision of ISO 19111 that supports spatiotemporal CRS and the existing ISO 19107 GM Point is implicitly assumed to be located in a spatial CRS In particular GML s implementation of GM_Point Implement gml Point does not support spatiotemporal coordinates Therefore these coverage types are modelled here as lt lt imp
64. the grid point locations explicitly as a sequence of direct positions in a defined sequence order csml GridPointDescription 10 2 or listing the coordinate values for each coordinate system axis separately over the grid point locations csml GridOrdinateDescription 10 3 The latter allows efficiency for the common case where an axis of the referenceable grid is aligned with a coordinate system axis The csml ReferenceableGrid implements ISO 19123 CV_ReferenceableGrid see D 2 11 and ISO 19123 2005 8 10 and is defined as an extension to gml Grid by adding a csml coordTableTransform property of type csml GridCoordsTableType lt element name ReferenceableGrid type gml ReferenceableGridT ype substitutionGroup gml Grid gt lt complexType name ReferenceableGridType gt lt annotation gt lt documentation gt An implementation of CV_ReferenceableGrid of ISO 19123 The association role crs to the SC_CRS to which it is referenceable is implemented using the gml SRSReferenceGroup attributeGroup inherited from gml Grid lt documentation gt lt annotation gt lt complexContent gt extension base gml GridType gt lt sequence gt lt element name coordTransformTable type csml GridCoordinatesTablePropertyType gt lt sequence gt lt extension gt 03 Feb 2007 54 Climate Science Modelling Language Version 2 lt complexContent gt lt complexType gt A property type for the csml ReferenceableGrid is also defined
65. types was illustrated earlier and is reproduced here for convenience cd Abstract CSML Feature CV_Coverage Discrete Coverages CV_DiscreteCoverage locate DirectPosition Set lt CV_GeometryValuePair gt implement domainSet parameter Important elements to note are e A CSML Feature Type realises a type representing a processing affordance Thus the operations of the type are inherited and in the CSML application of this pattern attributes of the type are copied down not strictly required by UML e A CSML Feature Type represents some observed or simulated physical parameter modelled through the O amp M Phenomenon class taxonomy e The value of this parameter is provided by a CSML coverage A coverage is conceptually a mapping from some spatiotemporal domain to a value range Figure 24 e CSML feature types are distinguished primarily on the basis of the geometry of the coverage domain There is a strong relationship between these sampling geometries and the Feature Type operations that are afforded 03 Feb 2007 25 Climate Science Modelling Language Version 2 Figure 24 GML coverage model Range attribute values B The set of 13 CSML Feature Types are listed in Table 2 below Table 2 CSML Feature Types Feature type PointFeature PointSeriesFeature TrajectoryFeature PointCollectionFeature ProfileFeature Profil
66. ular ArrayDescriptor instance within a CSML StorageDescriptor document The role specifies the nature of the storage resource g it could provide a mime type or be a well known URI identifying a particular resource type A CSML StorageDescriptor will be identified through the URI http ndg nerc ac uk fileFormat csmlStorageDescriptor The arcrole attribute specifies the nature of the storage artefact relative to the CSML element from which the xlink originates CSML exploits the syntax of URI and bends the semantics to assert that the logical content described by the storage descriptor should be logically inserted into the CSML document at a point given by a particular relative XPath The mechanism is best illustrated by example Consider a GML ReferenceableGrid instance A portion might look as follows lt csl gridOrdinate gt lt csml GridOrdinateDescription gt lt csml coordAxisLabel gt Geodetic longitude lt csml coordAxisLabel gt lt csml coordAxisValues gt lt csml SpatialOrTemporalPositionList gt lt csml coordinateList srssName WGS84 gt 13 5 24 9 32 4 37 7 41 5 46 8 54 4 65 7 lt csml coordinateList gt lt csml SpatialOrTemporalPositionList gt lt csml coordAxisValues gt lt csml gridAxesSpanned gt x lt csml gridAxesSpanned gt lt csml sequenceRule axisOrder 1 gt Linear lt csml sequenceRule gt lt csml GridOrdinateDescription gt lt csml gridOrdinate gt Suppose however that the longitude valu
67. ving platforms Temporal reference systems are subclassed as shown in Figure 16 An ordinal reference system is used for instance for specifying time relative to geological eras A temporal coordinate system refers a time instance to an origin while calendars and clocks specify an absolute date and time with respect to a defined calendar system TM_ReferenceSystem name RS Identifier domainOfValidity 0 EX Extent 3 TM_Calendar TM_Clock fu orators M CoordlnateSyste Figure 16 Temporal reference systems from ISO 19108 XML encodings for defining reference systems are provided in GML viii and not reproduced here 03 Feb 2007 20 Climate Science Modelling Language Version 2 4 UTILITY TYPES CSML defines some utility types not provided by GML These are described here 4 1 TimeValueList TimePositionListType timePositionList TimeSeries CSML has a requirement to represent efficient lists of time instants Several constructs are defined for this purpose mostly by analogy with existing GML structures A csml TimeValueList is defined as a list of gml TimePositionUnion Figure 17 This enables a compact representation for a list of time positions lt simpleType name TimeValueList gt lt annotation gt lt documentation gt Provides a list of GML s TimePositionUnion see GML 3 2 sect 15 2 2 7 lt documentation gt lt annotation gt list it
68. xlink mechanism to CSML storage descriptors in a logically separate document 3 With the sole exception of a very limited and inadequate representation of coverage range data which if encoded within a single record interleaved but not band sequential etc file may be referenced through the gml File element 03 Feb 2007 14 Climate Science Modelling Language Version 2 For purposes of maintenance and convenience a simple wrapping schema provides a root Dataset element that includes both a GML document and a storage descriptor document Figure 8 These various elements are described in more detail in the next chapter lt Dataset gt lt csml FeatureCollection gt lt csml FeatureColleckion gt lt csml StorageDescriptor gt lt csml StorageDescriptor gt lt Dataset gt Figure 8 CSML v2 Dataset structure 03 Feb 2007 15 Climate Science Modelling Language Version 2 3 CSML DATASET A brief overview of the CSML Dataset structure was given above 2 4 It is described here in more detail A CSML Dataset consists of two components a CSML FeatureCollection and a CSML StorageDescriptor 3 1 CSML FeatureCollection A CSML FeatureCollection is modelled as shown in Figure 9 As required by GML viii 9 1 10 2 3 a feature collection is modelled itself as a feature type E de cd Feature Collection J FeatureT ype CSMLFeatureCollection crsDictionary Dictionary 0 1
69. ype An example XML encoding is shown in Figure 41 This example utilises all the optional attributes and demonstrates both the regular expression and numeric transformation The result of this array descriptor is a five by two array of temperatures ranging from 6 to 14 with the final two values equal lt InlineArray gt lt arraySize gt 5 2 lt arraySize gt lt uom gt udunits xml degreeC lt uom gt lt numericType gt float lt numericType gt lt regExpTransform gt s 10 9 ge lt regExpTransform gt lt numericTransform gt 5 lt numericTransform gt lt values gt 1 23456789 10 lt values gt 03 Feb 2007 43 Climate Science Modelling Language Version 2 lt InlineArray gt Figure 41 InlineArray for value array TBD need to define precise syntax and semantics for numericTransform and regExpTransform use flexible perl regexp model 6 1 3 ArrayGenerator If the numeric values in an array follow a simple pattern it is more efficient to encode them implicitly through a formulaic expression The ArrayGenerator class provides this facility One attribute is defined e expression provides a formulaic expression defining values to be generated implicitly An example XML encoding is shown in Figure 42 This example generates a sequence of 10001 values representing five minute increments in time from zero lt ArrayGenerator gt lt arraySize gt 10001 lt arraySize gt lt uom gt udunits xml minute lt uom gt lt numericType

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