Web Map Service (WMS) provides a simple HTTP interface for requesting geo-registered map images from one or more distributed geospatial databases. Web Coverage Service (WCS) defines a standard interface and operations that enable interoperable access to geospatial "coverages".

Through the ORNL DAAC OGC services users can:

• Preview ORNL DAAC data files
• Download data files in user-defined spatial extent, projection, resolution, and format

The Capabilities documents for the ORNL OGC services are:

• OGC WMS v1.1.1
• OGC WCS v1.0.0

The ORNL DAAC has also developed a data download interface based on the ORNL DAAC OGC Web services. Click here to access this interface. An explanation of this ORNL DAAC OGC data download interface is provided below.

Visualization / Download Interface

The data visualization/download interface consists of:

1. Metadata section
2. Data Preview section
3. WCS download parmeters section
4. OGC request URL section

Explanation of the various components is provided below:

[1] Pan the current map left, right, bottom, or up.

[2] Zoom in, Zoom out, or Zoom to full extent.

[3] Use mouse to pan the current map extent to left, right, bottom, or up.

[4] "Select Subset Extent" tool. When this tool is activated, users can draw a rectangle to select a region as the spatial extent for data download through WCS.

[5] "Drag to Zoom" tool. When this tool is activated, users can draw a rectangle to zoom the map to the selected region.

[6] Preview image of a selected time step of the data granule. By default, the preview image of first time step is displayed.

[7] An orange color rectangle showing the region selected using the "Select Subset Extent" tool.

[8] A blue color rectangle showing the spatial extent of the data granule.

[9] Click to open the map controls box, through which users can hide or show layers on the map widget, including: background layer, data layer, selected region box, and native spatial bounding box. An example of the map controls box looks like:

[10] Background Map.

[11] Link to a legend image of the data granule. The legend image is generated using WMS's GetLegendGraphic method. An example of the legend is below:

[12] Change the color scheme to match the min-max range of the data granule. By default, the min-max range of the entire dataset is used. By turning "Enhance Image Display" on, the color scheme will be changed to use value range of the data granule.

[13] The "OGC Requests Section" contains URL links to each WCS,WMS request: GetMap,GetCapabilities, DescribeCoverage, and the most recent GetCoverage request. The GetCapabilities request will get the whole Capabilities XML document. The DescribeCoverage request will get the coverage description XML document for the current data granule.

[14] This box lists all the supported projections for this data granule. By default the data granule's native projection is selected. Users can select any other projection from the list. The data preview image will also be projected into the selected projection and the spatial resolution and spatial extent information will also be updated.

[15] If a data granule contains multiple time steps, this button will appear. This tool displays all the time steps at certain user specified interval.