The EFDC+ code has been upgraded to allow allows the export of NetCDF-CF (NetCDF- Climate and Forecast) formatted data. This development has been conducted with the goal of providing allows EFDC+ output that can to be read and displayed on web servers.
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• Establish an interface standard that simplifies the design of new software for accessing geoscience data.
The new version of EFDC+ is able to export the native output in NetCDF-CF format for Windows and Linux. EE_Explorer, the pre- and post-processor for EFDC+ can also convert EFDC *.OUT files to netCDF .nc files, including the derived WQ parameters. EFDC+ currently exports 44 parameters to NetCDF format as listed at the end of this document..
EFDC+ for EE10, exports the NetCDF files at the same interval that it produces the EFDC Model model linkages files, which is set in the tab for Timing and Linkage | Linkage | NetCDF.
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Figure 1. NetCDF Setting.
Then, the user can select which parameters they want to output from the water column or the sediment bed. Some options for the sediment bed are not yet enabled and will be added to EE in future releases.
In the File Creation frame, the user is given the option of EFDC+ generating a Single File, or Multiple Daily Files.The Multiple Daily Files option provides one netCDF file for each one day (24 hours) of model output. NetCDF files (.nc files) are placed in the #output folder along with the EFDC output. The snapshots for the NetCDF files determined by the setting for the interval for the EE linkage file and the user can change the snapshot interval by changing the EE linkage options, Note that linkage frequency should be 10 minutes or more for proper display in ArcGIS tools. After setting these options the user should save their model and run EFDC+, which will then export the NetCDF .nc files to the #output folder.
Note that the calendar date is the default date in the NetCDF output.
1.1 Displaying NetCDF Output
There are a number of options available to the user for displaying netCDF output such as using ArcGIS, or using web-based tools such as ncWMS. Some of these are outlined here to help the user to become familiar with these tools.
1.1.1. Convert to Text
To convert the .nc file to s text file, the user can download the ncdump.exe tool and follow step-by-step instruction in UNIDATA.
1.1.2. Using ArcMap
A detailed guidance video for visualizing NetCDF output using ArcMap has been prepared by DSI and made available here: https://www.youtube.com/watch?v=vgT7dN4UK44
The basic steps involve selecting the ArcToolbox > Multidimensional Tools > Make NetCDF Feature Layer
Figure 2. ArcGIS reading the NetCDF file.
1.1.3. Using NCWMS
ncWMS is a Web Map Service for geospatial data that are stored in CF-compliant NetCDF files. The intention is to create a WMS that requires minimal configuration: the source data files should already contain most of the necessary metadata. ncWMS is developed and maintained by the Reading e-Science Centre at the University of Reading, UK. The latest version is 1.3, released in August 2014.
ncWMS is implemented in Java as a web application. To install ncWMS you simply place the WAR (Web ARchive) file in your application server of choice (e.g. Tomcat).
ncWMS relies heavily on the Java NetCDF interface from Unidata. This library does a lot of the work of metadata and data extraction. In particular the GridDatatype class is frequently used to provide a high-level interface to gridded geospatial NetCDF files. The library will also read from NetCDF files on HTTP servers and from OPeNDAP servers. From http://godiva.reading.ac.uk/ncWMS2/Godiva3.html
ncWMS loads native netCDF files and displays them on a web browser. To make the output the same as EE8 would require further adjustment to the tool. For the purposes of this demonstration, the basic display of the output is shown in the next section.
1.1.4. Using Ocean Data View
Ocean Data View (ODV) is a software package for the interactive exploration, analysis, and visualization of oceanographic and other geo-referenced profile, time-series, trajectory or sequence data.
ODV supports the netCDF format and lets you explore and visualize CF, COARDS, GDT, and CDC compliant netCDF datasets. This works with netCDF files on your local machine as well as with remote netCDF files served by an OPeNDAP server.
1.2 Examples of Model Output
1.2.1. Water Quality Model
To demonstrate the netCDF output is consistent with the data viewed in EE, a number of comparisons have been made for different models. Examples of an output from the West Lake WQ model in EE, ArcGIS and ncWMS are shown in Figure 3, Figure 4 and Figure 5 respectively. Note that the West Lake model may be downloaded from the EE website.
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Figure 3. EE display of EFDC+ output – DO at 137.001
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