This data recipe guides users in creating a time-enabled multidimensional mosaic dataset using NetCDF files within the Geographic Information Systems (GIS) desktop program ArcGIS Pro. It also demonstrates how to combine multiple NetCDF files into a mosaic, and covers how to perform data prep, add data to the mosaic, build multidimensional info, and set mosaic properties. Mosaic datasets can be used in data analysis and visualizations.

The data used in this tutorial comes from NASA’s Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). If you’d like to follow along, you can download these data by clicking the following links:  

• Download via Earthdata Search 

• Direct file download: data download link 1, link 2, and link 3 

If you’d like to watch a video tutorial for this content, you can find it at NASA Earthdata’s YouTube channel.  

Note: An Earthdata Login account is needed to download these data. You can visit this tutorial to learn how to create an account. 

1. Prepare Your Data With Panoply 

Panoply is a free software that plots geo-referenced data from file types such as NetCDF, HDF, or GRIB. Download Panoply.

1. Inspect the NetCDF Files: Ensure the files contain spatial data compatible with ArcGIS Pro, such as variables with latitude, longitude, and time dimensions.
2. Consistent Variables: Ensure all NetCDF files contain the same variable(s) you want to include in the mosaic dataset. 

2. Create a File Geodatabase 

1. Open ArcGIS Pro and create a new project or open an existing one.
2. In the Catalog Pane:
   1. Right-click on your project folder and choose New > File Geodatabase.
   2. Name your geodatabase. 

3. Create a Mosaic Dataset 

1. In the Catalog Pane:
   1. Right-click on the geodatabase you just created.
   2. Choose New > Mosaic Dataset.
2. In the Create Mosaic Dataset tool:
   1. Output Location: Should be the new geodatabase.
   2. Mosaic Dataset Name: Provide a name for the mosaic dataset.
   3. Coordinate System: Set the spatial reference system appropriate for your data (e.g., WGS 1984, EPSG:4326).
3. Click Run to create the mosaic dataset.
4. The mosaic dataset should now be nested within the geodatabase, though it will be initially empty.

4. Add NetCDF Files to the Mosaic Dataset 

1. Open the Add Rasters to Mosaic Dataset tool:
   1. Go to the Analysis tab > Tools > Search for Add Rasters to Mosaic Dataset.
2. Set the following parameters:
   1. Input Mosaic Dataset: Select the mosaic dataset you created.
   2. Raster Type: Select NetCDF from the dropdown menu.
   3. Processing Templates: Leave as “Default.”
   4. Input Data: Select or browse to the file or folder containing your NetCDF files.
   5. Under Advanced Data Input Options: Include Subdirectories, check this if your NetCDF files are organized in subfolders.
   6. Enable pixel cache for faster rendering.
   7. Calculate Statistics.
3. Click Run to add the NetCDF files.

6. Visualize and Analyze the Mosaic Dataset 

1. Drag the mosaic dataset into your map.
2. Use tools like Symbology to visualize specific variables (e.g., temperature, precipitation).
3. Use analysis tools such as Temporal Profile (step 8) in ArcGIS Pro to derive insights from the dataset. 

7. Optional: Time-Enabled Visualization (If Not Auto-Read) 

If your NetCDF files include a time dimension: 

1. Right-click on the mosaic dataset in the Contents Pane and choose Properties.
2. Go to the Time tab:
   1. Enable the time dimension.
   2. Set the start time field to match the time variable in your NetCDF files.
3. Use the Time Slider to explore temporal changes. 

8. Temporal Profile 

9. Save and Document 

1. Save your project to retain the mosaic dataset configuration.
2. Document the mosaic dataset by adding metadata (right-click on the dataset in the Catalog Pane).