WCS Outline

From Earth Science Information Partners (ESIP)

General Description of Atmospheric Model Evaluation Network (AMEN)

Drawing from the GEO Work Plan (Task DA-09-02d)Task

Demonstrate the use of web services to compare global and regional atmospheric models (including atmospheric chemistry/air quality models). Apply to a variety of Earth observations from distributed archives using standardized approaches to evaluate and improve model performance. Draw upon and contribute to the work of the Task Force on Hemispheric Transport of Air Pollution under the Convention on Long-range Transboundary Air Pollution, the IGAC-SPARC Atmospheric Chemistry and Climate Initiative, AeroCOM, and the Air Quality Model Evaluation International Initiative.

HTAP Data Network Pilot

Explain TF HTAP, participating nodes http://wiki.esipfed.org/index.php/HTAP_GEOSS

The GEOSS air quality community and its projects has promoted the use of CF-netCDF as the binary incoming of data both for storage as well as for transmission of AQ-relevant data between servers and clients. The CF-netCDF data standard and the OGS WCS, WFS and WMS data access protocols constitutes a complete package for establishing a network of interoperable data finders, servers and clients.

The network Common Data Form (netCDF) binary data encoding standard

The NetCDF (network Common Data Form) can be used to store and communicate multidimensional data, such as arising from Earth Observations and models. The NetCDF data model is particularly well suited for storing related arrays containing atmospheric and oceanic data and models. Climate and Forecast Metadata Conventions (CF) are used in conjunction with NetCDF as a means of specifying the semantic information. The semantic metadata is conveyed internally within the NetCDF datasets which makes NetCDF is self documenting. This means that it can associate various physical quantities (such as location, pressure and temperature) with spatio-temporal locations (such as points at specific latitudes, longitudes, vertical levels, and times).

This standard has been formally recognized by US Government NASA and NOAA standards bodies. Recently, UCAR has introduced NetCDF as a candidate OGC standard to encourage broader international use and greater interoperability among clients and servers interchanging data in binary form. This is the initial step in a longer-term plan for establishing CF-netCDF as an OGC standard for binary encoding. This will enable standard delivery of data in binary form via several OGC service interface standards, including the OGC Web Coverage Service (WCS), Web Feature Service (WFS), and Sensor Observation Service (SOS) Interface Standards.

For the past two decades, with the help of the U.S. National Science Foundation, netCDF was maintained and actively supported by the University Corportion for Atmospheric Research (UCAR) .  NetCDF is a set of software libraries and machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data. NetCDF has a strong and user community Unidata is supported by the U.S. National Science Foundation for the past 25 years.

       Explain TF HTAP, participating nodes
       uFIND Interface
       ufind/facets - http://datafedwiki.wustl.edu/images/0/04/IGARSS_InternationalAQCommunity.ppt

Development and Conventions and Standards


Web Coverage Service (WCS) Implementation Specification.OGC 07-067r5

A WCS provides access to potentially detailed and rich sets of geospatial information, in forms that are useful for client-side rendering, multi-valued coverages, and input into scientific models and other clients. The WCS may be compared to the OGC Web Map Service (WMS) and the Web Feature Service (WFS); like them it allows clients to choose portions of a server's information holdings based on spatial constraints and other criteria. Unlike the WMS [OGC 06-042], which portrays spatial data to return static maps (rendered as pictures by the server), the Web Coverage Service provides available data together with their detailed descriptions; defines a rich syntax for requests against these data; and returns data with its original semantics (instead of pictures) which may be interpreted, extrapolated, etc. – and not just portrayed. Unlike WFS [OGC 04-094], which returns discrete geospatial features, the Web Coverage Service returns coverages representing space-varying phenomena that relate a spatio-temporal domain to a (possibly multidimensional) range of properties.

The Web Coverage Service provides three operations: GetCapabilities, DescribeCoverage, and GetCoverage. The GetCapabilities operation returns an XML document describing the service and brief descriptions of the coverages that clients may request. Clients would generally run the GetCapabilities operation and cache its result for use throughout a session, or reuse it for multiple sessions. When the GetCapabilities operation does not return such descriptions, then equivalent information must be available from a separate source, such as an image catalog.

The DescribeCoverage operation lets clients request a full description of one or more coverages served by a particular WCS server. The server responds with an XML document that fully describes the identified coverages.

The GetCoverage operation is normally run after GetCapabilities and DescribeCoverage operation responses have shown what requests are allowed and what data are available. The GetCoverage operation returns a coverage (that is, values or properties of a set of geographic locations), encoded in a well-known coverage format. Its syntax and semantics bear some resemblance to the WMS GetMap and WFS GetFeature requests, but several extensions support the retrieval of coverages rather than static maps or discrete features.

WCS Introduction

1 Scope This document specifies how a Web Coverage Service (WCS) describes and delivers multi-dimensional coverage data over the World Wide Web. This version of the Web Coverage Service is limited to describing and requesting grid (or "simple‖) coverages. Grid coverages have a domain comprised of regularly spaced locations along 0, 1, 2, or 3 axes of a spatial coordinate reference system. Their domain may also have a time dimension, which may be regularly or irregularly spaced. A coverage defines, at each location in the domain, a set of fields that may be scalar-valued (such as elevation), or vector-valued (such as brightness values in different parts of the electromagnetic spectrum). These fields (and their values) are known as the range of the coverage. The WCS interface, while limited in this version to regular grid coverages, is designed to extend in future versions to other coverage types defined in OGC Abstract Specification Topic 6, "The Coverage Type" [OGC 00-106].

Development of CF Naming Convention and CF Consistency Tools

WCS Server Software for Grid and Point Data

WCS Server StationPoint Data

WCS Server Cube Data


Clients Nodes and User Interfaces

FZ Juelich


NASA Giovanni