Animating NetCDF Data in ArcMap
Tim Whiteaker, CRWR
NetCDF is a data format and library designed to store multidimensional arrays of scientific data, and is widely used in the atmospheric sciences and oceanography. Unidata, a largely NSF funded program under the University Corporation for Atmospheric Research (UCAR), is the “home” of netCDF and provides the following definition:
NetCDF (network Common Data Form) is an interface for array-oriented data access and a library that provides an implementation of the interface. The netCDF library also defines a machine-independent format for representing scientific data. Together, the interface, library, and format support the creation, access, and sharing of scientific data. <http://www.unidata.ucar.edu/software/netcdf/>
ArcGIS version 9.2 introduces support for working with netCDF files. With the new Multidimension Tools toolbox, you can create raster layers, feature layers, and table views from netCDF data in ArcMap, or convert feature, raster, and table data to netCDF.
The Multidimension Tools toolbox is new for ArcGIS 9.2
Also new in ArcGIS 9.2 is the Animation toolbar and Animation Manager, which supports the animation of data through space and time.
This document walks you through the procedure for downloading and animating netCDF data in ArcMap. The exercise uses precipitation model forecasts from NCEP’s North American Mesoscale model.
To complete this exercise, your computer must have
An ArcMap document (netCDF.mxd) and basemap data (Continents.shp) have been prepared for you. This data may be downloaded here: NetCDF.zip.
This zip file also includes the netCDF file (NAM_CONUS_12km_20060721_1200.grib2.nc) shown in the screenshots in this exercise. In the exercise, you will download your own netCDF file. However, NAM_CONUS_12km_20060721_1200.grib2.nc is provided for reference, and may come in handy if the netCDF server used in the exercise is down.
The National Centers for Environmental Prediction (NCEP) produce the North American Mesoscale model (also known as the North American Model or NAM), which predicts climate variables up to 84 hours into the future. The model is run every six hours, with a catalog of results published at:
Note: The 8080 server is meant for a modest academic community. If you want to use it more often than just trying it out, contact firstname.lastname@example.org and let them know who you are and what your planned use is.
In this portion of the exercise, you will download a netCDF
file of total precipitation data (in millimeters) from the
Note: If you do not have a high speed Internet connection, or if the netCDF server is down, you may skip to the Adding NetCDF Data to ArcMap section of the exercise and use the NAM_CONUS_12km_20060721_1200.grib2.nc file that was included in the zip file for this exercise.
NetcdfServer provides a user interface for extracting a portion of a grib2 dataset. You will use NetcdfServer to download total precipitation data from within the dataset.
For the bounding box and forecast hours, you will accept the defaults in order to download data for the entire prediction time range and the entire model area.
You have now downloaded predicted precipitation data from
With the Multidimension Tools, you can visualize netCDF data as a feature layer, raster layer, or table view in ArcMap. In this portion of the exercise, you will add the precipitation data to ArcMap as a netCDF raster layer.
Next, you will use the Animation Manager to animate the precipitation data through each time step.
The Animation Manager in ArcGIS 9.2 is a powerful utility with features for creating various types of animations in ArcMap. More information and tutorials about animating in ArcMap can be found in the ArcGIS Desktop Help in the Mapping and Visualization heading.
In this portion of the exercise, you will use the Animation Manager to animate the netCDF precipitation raster through time. The first step is to create a new animation track and keyframes.
In the Create Animation Keyframe window that opens, you will create a new track for your animation, and create the start and end keyframes within the track. These are the minimal keyframes required for an animation.
The next step is to use the Animation Manager to calculate the time stamps for the start and end keyframes, and specify the duration of each frame.
There is no need to specify an End Time field, because our data occur at regular steps. You would specify the End Time field for data with irregular time steps. See the ArcGIS help for more information.
Now you’re ready to animate the data.
The display will animate the precipitation data through time. A text label shows the current time stamp for the data, and the progress bar at the bottom of the ArcMap display shows the total progress of the animation.
Congratulations! You have downloaded precipitation data in netCDF format, added the data to ArcMap as a raster layer, and animated the data through time. Be sure to peruse the NCEP catalog for more information about available datasets, and check out the ArcGIS Help for more information about customizing animations in ArcMap.
Phone: (512) 471-0570
These materials may be used for study, research, and education, but
please credit the authors and the Center for Research in Water Resources, The