In response to the growing need for a modern, up-to-date technology for exchanging meteorological data, Data Modeling is tasked with developing logical data models for products that serve the nation's weather enterprise. These models, which describe the content and relationships of meteorological data, can be expressed in any number of physical data models, and in this effort, it is XML (eXtensible Markup Language), a widely recognized standard for data interchange over the Internet.

MDL's role is to create logical data models and corresponding OGC/ISO compliant XML schemas of meteorological products that serve the nation's needs for weather data. 

Weather Schema Development by MDL

This page provides a brief introduction to the various GML-based XML schemas used to encode products that originate in the United States. These schemas fall into two general categories: schemas governed by the United States exclusively; and extensions to schemas governed by other Standards Development Organizations (SDO).

The World Meteorological Organization (WMO) and the International Civil Aviation Organization (ICAO) have jointly developed an XML package named the ICAO Meteorological Information Exchange Model (IWXXM) that represents meteorological information that is compatible with both WMO and aviation systems. The IWXXM is currently comprised of three packages named "ISO 19136 GML", METCE and AIXM.

Weather Schema Extensions for IWXXM (IWXXM-US)

Developed by MDL, the schemas in the IWXXM-US namespace along with corresponding UML models are to support the United States' Federal Aviation Administration's (FAA) filed differences of the five Traditional Alphanumeric Codes--AIRMET, METAR, SIGMET, SPECI and TAF--as detailed in various United States operational meteorological agencies' handbooks, directives and instructions. Thus, the IWXXM-US schemas supplement--not replace--the IWXXM schemas. Since version 2.0 and subsequent releases, the IWXXM schemas allowed for arbitrary content to appear in the resulting IWXXM XML documents. Schemas in the IWXXM-US namespace provides the required XML constructs to encode the unique content of the United States aeronautical products. Further documentation on how IWXXM and extended content schemas, such as IWXXM-US, work together is available here.

The authoritative location of IWXXM-US schemas, examples of IWXXM-US content appearing in IWXXM XML documents, and the UML models are hosted on these pages. The following documents provide information and examples on the IWXXM-US XML data types:

Weather Schemas Governed by the United States (USWX)

A set of UML models and associated schemas under a "USWX" namespace were developed by MDL to support XML encoding of meteorological products issued by the United States and not found in ICAO Annex 3. The list of products selected to be transformed into XML were determined exclusively by Federal Aviation Administration's NextGen project requirements. Schemas, XML examples and documentation for USWX products are hosted on these pages.