wiki:tickets/277

Proposed updates to the CIM Grid logical data model

Creator: Phil
Date: 16 July 2009
Trac Ticket: #277

Objective of this Proposal

This wiki page outlines proposed updates to the CIM Grid data model. It is proposed that the changes, if considered desirable, are incorporated into the next formal release of the CIM conceptual model and any XML application schemas derived from it.

The proposed changes are in response to email correspondence on the Metafor and Curator mailing lists.

1. Addition of constructionMethod attribute to GridTile class

ClassGridTile
AttributeconstructionMethod
Data TypeString
ObligationOptional
Value DomainControlled vocabulary initially comprising the following values: ['Arakawa A', 'Arakawa B', 'Arakawa C', 'Arakawa D', 'Arakawa CD', 'Rotated Arakawa E', 'Randall Z', 'Charney-Phillips', 'Lorenz', 'L Grid', 'Equivalent CP Grid']
PurposeTo enable the method of construction of a earth system model grid to be characterised succinctly. This may then facilitate search operations for specific grid types.

Discussion Points

(Phil, 16/07/09) Should this attribute be attached to the GridTile class or the GridMosaic class? In some cases the construction method carries (implied) information about the horizontal and/or vertical staggering between the subgrids making up a model (super)grid, or the data fields based upon it. Hence it may make more sense for this attribute to be associated with GridMosaic objects.

Decision

Defer to subsequent CIM release. Seek further usage requirements and applications from Balaji and others.

2. Addition of verticalResolution attribute to GridTile class

ClassGridTile
AttributeverticalResolution
Data TypeString
ObligationOptional
Value DomainFree text
PurposeProvides a place to specify a free text description of the vertical resolution of a grid tile.

Discussion Points

(Phil, 16/07/09) The motivation for this new attribute is to mirror the distinction made in other metadata schemes (e.g.  DIF) between horizontal and vertical resolution. In the current CIM Grid data model (v1.1), the resolution attribute on the GridTile class was (I think) intended to be used solely to describe horizontal resolution (see next entry), though it could of course double up for both.

(Sylvia, 22/07/09) ESG has had a verticalResolution property for just this purpose. As I recall, the reason we were not pushing to have this in the grid UML was because Balaji's program will not be providing us with vertical grid information, at least it does not now.

Decision

Accepted.

3. Rename resolution attribute to horizontalResolution on GridTile class

ClassGridTile
AttributehorizontalResolution
Data TypeString
ObligationOptional
Value DomainFree text
PurposeProvides a place to specify a free text description of the horizontal resolution of a grid tile.

Discussion Points

(Phil, 16/07/09) The renaming of this attribute is contingent upon acceptance of the verticalResolution property (see previous entry). If the decision is to continue to use the single resolution attribute then this change is unnecessary.

(SJM, 22/07/09) I have no issue with this at all.

Decision

Accepted.