• Version 1.0 (of which this is the first release candidate) is the initial version of metce, and is intended to meet ICAO aviation requirement to support Amendment 76 to ICAO Annex 3 that will allow bilateral exchange of the information traditionally exchanged in TAF, METAR or SPECI in XML (for those states in a position to do so).
• Later versions of metce will be developed to support more WMO Programmes, addressing weather, water and climate information exchange.
• The metce model references WMO code tables (defined in WMO 306, Manual on Codes)through registries (referred to through the URIs http://data.wmo.int/def/....) that are are not yet implemented. The example XML instances show how these are structured. The registers are expected to be included with RC2.
• iwxxm is an application schema being developed by ICAO to represent TAF, METAR, SPECI and SIGMET, and is included in this release candidate.
• Each of the models in this release candidate is provided as a UML conceptual model and a XML schema physical model derived from the UML.
• The approach taken conforms to ISO 19109 ("Geographic information — Rules for application schema") and OGC 10-025r1 "Observations and Measurements - XML implementation" (OMXML).
• Place-holders are used to illustrate where URIs (Uniform Resource Identifiers) will be used in the final release - although the final URIs will resolve as URLs, the indicative versions in RC1 do not have corresponding web pages. These place-holders may not be unique, and they may take on other meanings in the future.

metce

metce provides a set of foundation building blocks that can be built into an application schema; iwxxm is the first example.

The WMO Logical Data Model (known as metce)is implemented in three parts:

• metce (the WMO Logical Data Model itself)
• Meteorological basic types (these are fundamental concepts at the logical level of the GML Measure class)
• Observable Property Model (this may be replaced by a package being developed by OGC when the latter is finalised)

Meteorological basic types

Package 'Meteorological basic types' contains:

• a palette of classes specialising Measure (or subclasses thereof) for meteorological, hydrological and oceanographic physical properties;
• a palette of «CodeList» classes for expressing nominal values of meteorological, hydrological and oceanographic physical properties; and
• various other common basic types used in describing meteorological phenomena.

As GML is currently specified, Measure (from ISO 19103 Basic types) cannot be specialised. Therefore, the definition of quantity-value classes such as AirTemperature as specialisations of Measure is illegal with respect to GML.

For this reason 'Meteorological basic types' is published as a separate package outside the scope of METCE.

As a complement to "ISO 19103 Basic types", "Meteorological basic types" will provide a set of classes and XML types required to describe the physical quantities of interest to meteorologists.

Observable Property Model

The 'Observable Property Model' provides a framework for qualifying or constraining physical properties. For example, the model enables a standard physical property such as "air temperature" to be qualified as "daily maximum air temperature" by specifying an aggregation period of 24-hours using the "maximum" statistical function.

This model is derived from work undertaken in the OGC Sensor Web Enablement SWG.

As an interim measure, the WMO Logical Model includes the Observable Property Model. Further discussions on the governance arrangements of this model are pending.

metce (Modèle pour l'Échange des informations sur le Temps, le Climat et l'Eau)

The WMO Logical Data Model is intended to support the entire scope of WMO concerns: weather, climate and water. To reflect this scope, the WMO Logical Data Model is named 'Modèle pour l'Échange des informations sur le Temps, le Climat et l'Eau' (METCE). In English, it may also be known as the ‘METeorological Community Exchange’ model.

WMO METCE is intended to provide conceptual definitions of meteorological phenomena, entities and concepts in order to underpin semantic interoperability in the weather, climate and water domain.

The «Application Schema» includes:
specialisations of OM_Observation, OM_ComplexObservation and OM_DiscreteCoverageObservation classes (from ISO 19156)
a concrete implementation of OM_Process (from ISO 19156)
a number of meteorological feature types and categorisation schemes thereof.

The 'WMO METCE' «Application Schema» will typically be imported to provide a baseline conceptual model framework upon which community-specific Application Schema are based.

The iwxxm package, managed by ICAO provides two sets of components

• iwxxm - defines the reports required by ICAO
• saf - Simplified Aviation Features, that allow items such as airports, or runways to be described to the level of detail required for reporting aviation weather

iwxxm (ICAO Weather Information Exchange Model)

The ICAO Weather Information Exchange Model (IWXXM) package, including METAR, SPECI, TAF, and SIGMET reports as defined in ICAO Annex 3, 17th edition. These four reports are essential operational meteorology products used to enable safe and efficient air travel worldwide.

Structure of iwxxm package

This package builds upon the ISO 19100 family (ISO TC211) and WMO standard meteorological modeling constructs. Additionally, the constructs in this application schema refer to a number of aviation constructs such as FIR, Aerodrome, and Runway from the Simple Aviation Features package. The full relationship of this package with external dependencies are shown in the 'Package Dependencies' diagram.

While only four of the reports from Annex 3 are currently represented, this may be expanded in a future version.

Reports in the package - METAR/SPECI

Observation of meteorological conditions made at an aerodrome throughout the day. METARs may also include short-term forecasts of meteorological conditions

Reports in the package - TAF

Routine aerodrome forecasts of meteorological conditions

Reports in the package - SIGMET

Meteorological advisory concerning the occurrence and/or expected occurrence of weather phenomena which may affect the safety of aircraft operations, such as severe thunderstorms or turbulence

saf (Simple Aviation Features) package

Simplified features from the aviation domain, such as aerodrome and runway. These features are not intended for storage or transmission, merely simplified variants of aviation concepts that can be referenced from other packages.

The structure of the pages within the wiki that support this consultation is shown below.

• AvXML-1.0RC1-Info
  • AvXML-1.0RC1-Names
• AvXML-1.0RC1-FAQ
• AvXML-1.0RC1-Issues
• AvXML-1.0RC1-Table4678
  • AvXML-1.0RC1-Wx
• AvXML-1.0RC1-teleconf
  • AvXML-1.0RC1-Reg
  • AvXML-1.0RC1-Register
• AvXML-1.0RC1-tutorial
  • AvXML-1/0RC1-ObsProp-MetarOb
  • AvXML-1.0RC1-tutorial-example
  • AvXML-1.0RC1-tutorial-VA-sigmet