PRISM Metadata Issues

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PRISM Metadata Issues

• Loïs Steenman-Clark
• NCAS
• Department of Meteorology
• University of Reading, UK

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PRISM
PRISM European funded project 2001 2004
- Aims to provide the European Earth System
Modelling Community with a common
software infrastructure -
http//www.prism.enes.org
PSI - PRISM Support Initiative -
Multi-institute supported project to further the
PRISM infrastructure - Forum for
discussion, organisation of meetings workshop
A common software infrastructure
implies adherence to standards and use of
metadata
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• From the PRISM Exeter
• metadata meeting, March 2006
• Outcomes
• adoption of gridspec for the horizontal grid
  definition
• need for a standard controlled vocabulary for
  some semantic metadata eg horizontal grids
• precise definitions and conformity check needed
  of keywords used in Earth System metadata
• a better understanding of the vocabulary used
  for the elements
• in an Earth System Model framework

In a PRISM context
PRISM Infrastructure
Simulation start time - end time

model
component
Coupler OASIS
component
Application, when compiled
data
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• From the PRISM Exeter metadata meeting, March
  2006

• Things the meeting ducked out of
• dealing with vertical grids (CF for now)
• time metadata (use CF where possible)
• coupling framework metadata
• aggregation and management of metadata

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Metadata for PRISM
PMIOD
gridspec
component
NMM
gridspec
component
NMM
PMIOD
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• Couplers can be
• internal, hardwired into the modelling
  framework
• for example, the Unified Model
• generic, can be used within a framework, or
  standalone
• for example, OASIS
• bespoke, created on the fly within a
  modelling or coupling framework,
• for example, FLUME

difficult to have a coupling framework metadata
standard to accommodate all these possibilities
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As was agreed at the Exeter metadata meeting -
rather than analysing a gridspec file and
determining a local name for the grid, the
gridpsec would contain semantic metadata using a
controlled vocabulary.
Controlled vocabulary - used by different
communities
gridspec
Standard definition - used by couplers, grid
generators
With clear definitions different coupler metadata
should be interchangeable
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• Can we identify what semantic metadata for
  couplers or coupling frameworks needs to be
  standardised?
• From IPCC
• Coupling details PRISM
• What components are coupled together? SCC
• Variables exchanged? SMIOC (CF standard)
• frequency of coupling PSMILe /SMIOC
• conservation SMIOC but not yet available
• Are there other useful semantic metadata that are
  generic to all couplers and
• coupling frameworks?
• transformation/interpolation names OASIS
• exchange grid gridspec
• Who would manage this collective semantic
  metadata for coupling?

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• What areas of the PRISM syntactic metadata are
  under consideration?
• Constraint management
• We need to be able to express the limitations
  or restrictions or interactions of the
  component or the coupler. FLUME has an prototype
  constraint language in XML, is this the way to
  go?
• Technical metadata
• Within a coupling framework the elements
  componentscoupler need to share information
  about the parallel distribution of the grid, for
  example, on the computing platform.

• Aggregation of metadata
• As with the gridspec how do we combine and join
  the different
• metadata sources together?

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Next steps for PRISM metadata Working with
other coupling frameworks (ESMF,
FLUME) Development of controlled
vocabularies Discussion of dictionary
definitions for syntactic metadata
attributes Implementing metadata version control