OPeNDAP

The OPenDAP web app supports the OPeNDAP service for Multidimensional (NetCDF) resources or Composite resources with NetCDF file type. The OPeNDAP service in HydroShare is available only for the associated resource types shared in "Public" or “Published” status. OPeNDAP app enables users to access and subset the NetCDF file stored in HydroShare through an OPeNDAP data access form in a web browser or using existing OPeNDAP client software for data visualization or analysis. This will allow users to easily subset, visualize or analyze the shared dataset without downloading the whole file from HydroShare to local computers.

Example Uses of the App

OPeNDAP app can be opened from the “Web Apps” tab or “Open with” dropdown on the resource landing page of the associated HydroShare resources. We provide three use cases of how to use the OPeNDAP app and the OPeNDAP client software for data subset, visualization and analysis.

 

Use case 1: creating a new subset NetCDF file

An example use of opening the app directly could be that a HydroShare user wants to get a subset of the original dataset as a new NetCDF file. This workflow would look like this:

  1. Open the app from the resource landing page (example resource here). The resource type should be Multidimensional (NetCDF) resource or Composite resource with NetCDF  file type in it.The resource should be shared as “Public” or “Published”.
  2. The OPeNDAP data access form is shown (See Figure 1).
  3. Specify the variable and dimensions for data subset.
  4. Click “Get NetCDF3” or “Get NetCDF4”

Figure 1 OPeNDAP data access form for example Multidimensional (NetCDF) resource

 

Use case 2: resource visualization with Panoply

Panoply is an OPeNDAP client software for data visualization. Users can download and install it on the local PC. An example use is to access and visualize a Multidimensional (NetCDF) resource with Panoply without downloading the file to local PC. This workflow would look like this:

  1. Open the app and copy the Data URL from the OPeNDAP data access form. (See Figure 1)
  2. Open the Panoply software. Click File -> Open Remote Dataset. (See Figure 2)
  3. Paste the Data URL in the input window (See Figure 3)
  4. On the left panel, click a variable name for visualization (e.g. SWE). Click “Create Plot” and choose the plot type. Then click “Create” (See Figure 4 and Figure 5)

Figure 2 Add Remote dataset in Panoply


Figure 3 Paste the OPeNDAP Data URL in Panoply

 

Figure 4 Create a 2D plot for a variable in Panoply

 

Figure 5 Use Panoply to visualize the Multidimensional (NetCDf) resource in HydroShare



Use case 3: resource data analysis with NCO

NCO is an OPeNDAP client software for data processing and analysis. Users can download and install it on the local PC. An example use is to access and analyze the shared dataset with NCO without downloading the file from HydroShare. This workflow would look like this:

  1. Open the app and copy the Data URL from the OPeNDAP data access form. (See Figure 1)
  2. Write NCO commands to analyze the shared data using the Data URL for data access. (See Figure 6 and Figure 7)
  3. Share the code and result NetCDF files as new resource  in HydroShare for others to validate the work to support research reproducibility.

Figure 6 Example code using NCO commands to analyze the example resource

 

Figure 7 Visualization of the new results created by NCO commands

 

Credits, Authors, Contributors and Contacts

This app was created by the collaboration of USU and RENCI from HydroShare team.