IWXXM Packages

IWXXM is built on several packages. There is not yet a formal agreement between WMO and ICAO on how the packages will be managed. For convenience, in IWXXM v2 the packages are divided into a group that is concerned with the meteorological information content (this group is labelled as 'managed by WMO'), and a group that is concerned with how the meteorological information is applied within the aviation community (this group is labelled as 'packages managed for ICAO').

Packages managed by WMO

• metce - 'Modele pour l'Echange des informations sur le Temps, le Climat et l'Eau' (METCE) - a set of foundation building blocks to support application schema in the domains of interest to WMO, notably the weather, climate, hydrology, oceanography and space weather disciplines
• Observable Property Model (OPM) - based on work by the OGC Sensor Working Group, this allows creation of definitions that are derived from the meteorological basic types
• Feature Collection Model (COLLECT) - used to represent a collection of GML feature instances of the same type of meteorological information

Packages managed for ICAO

• iwxxm - ICAO Meteorological Information Exchange Model - defines the reports required by ICAO (the equivalent of METAR/SPECI, TAF, SIGMET, AIRMET, Tropical Cyclone Advisory (TCA) and Volcanic Ash Advisory (VAA)) that are built from the components of the packages managed by WMO.

More on the packages managed by WMO

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

• metce (the WMO Logical Data Model itself)
• Observable Property Model (this may be replaced by a package being developed by OGC when the latter is finalised)
• Feature Collection Model (for aggregation of meteorological reports of the same type)

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.

Structure of metce package

The "Application Schema" includes:

• 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.

metce

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

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.

Feature Collection Model

The 'Feature Collection Model' is used to represent a collection of GML feature instances of the same type of meteorological information. The intent is to allow XML encoded meteorological information to be packaged in a way that emulates the existing data distribution practices used within the WMO Information System (WIS) and Aeronautical Fixed System (AFS).
Notes

1. The collection of meteorological information is often referred to as a bulletin.
2. XML encodings of meteorological information are defined in Part D; for example FM 205-15 EXT IWXXM-XML.

More on the packages managed by ICAO (iwxxm)

The iwxxm package, managed by ICAO provides one set of components

• iwxxm - defines the reports required by ICAO

iwxxm (ICAO Weather Information Exchange Model)

The ICAO Weather Information Exchange Model (IWXXM) package, including METAR/SPECI, TAF, SIGMET, AIRMET, Tropical Cyclone Advisory (TCA) and Volcanic Ash Advisory (VAA) reports as defined in ICAO Annex 3, 19th 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 Aeronautical Information eXchange Model (AIXM) package. The full relationship of this package with external dependencies are shown in the 'Package Dependencies' diagram.

While only six of the reports from Annex 3 are currently represented, it will be further 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.

Reports in the package - AIRMET

Meteorological advisory concerning the occurrence and/or expected occurrence of specified en-route weather phenomena which may affect the safety of aircraft operations, and of the development of those phenomena in time and space.

Reports in the package - Tropical Cyclone Advisory (TCA)

Advisories reporting the occurrence and/or expected occurrence of tropical cyclone phenomena which may affect the safety of aircraft operations, and of the development of those phenomena in time and space.

Reports in the package - Volcanic Ash Advisory (VAA)

Advisories reporting the occurrence and/or expected occurrence of specified en-route volcanic ash phenomena which may affect the safety of aircraft operations, and of the development of those phenomena in time and space.  These phenomena are reported as impacted regions of airspace.