Download and Visualize NISAR SAR Data in QGIS Without Coding

NISAR (NASA-ISRO SAR) is a joint mission between NASA and the Indian Space Research Organisation (ISRO) that provides Synthetic Aperture Radar (SAR) data for monitoring ice movement, sea level rise, vegetation dynamics, ecosystems, and natural hazards. The satellite was launched in July 2025, and sample data became available in late January 2026. NISAR generates tens of terabytes of data per day, making it one of the most data-intensive Earth observation missions to date.

In this tutorial, I walk through how to use the NASA Earthdata QGIS plugin to search, download, and visualize NISAR data products directly in QGIS, no coding required.

What You Will Need¶

• QGIS installed via Pixi (follow the plugin installation instructions rather than using your system QGIS installation)

• A NASA Earthdata account (free registration)

• An internet connection to search and download data

NISAR Data Overview¶

Before diving in, I recommend reviewing the NISAR Data User Guide from the Alaska Satellite Facility (ASF). It is an excellent and comprehensive resource for understanding the mission and its data products.

NISAR data is organized into processing levels:

• Level 1: Raw or minimally processed data. Not georeferenced, so it is difficult to visualize on a map. Skip this unless you know how to process SAR data from scratch.

• Level 2: Geocoded products, including polarimetric covariance data (GCOV). These are georeferenced and ready to visualize.

• Level 3: Higher-level derived products such as soil moisture maps. Smaller file sizes and easier to interpret.

The sample data currently available covers locations in Antarctica (for ice movement monitoring) and parts of Africa (for vegetation monitoring).

Install the NASA Earthdata Plugin¶

Follow the installation instructions on GitHub to set up QGIS with Pixi and install the plugin. The plugin requires specific dependencies (such as oaccess), so using Pixi ensures everything works correctly.

Once QGIS is open:

1. Go to Plugins > Manage and Install Plugins.

2. Search for NASA Earthdata.

3. Click Install Plugin.

After installation, find the plugin under the NASA Earthdata menu. I recommend clicking Check for Updates to make sure you have the latest version with bug fixes and new features.

Authenticate with NASA Earthdata¶

You need a NASA Earthdata account to download data. If you do not have one, register at urs.earthdata.nasa.gov.

To authenticate in QGIS:

1. Go to NASA Earthdata > Settings.

2. Enter your username and password.

3. Click Test Credentials to verify.

Alternatively, the plugin can use a .netrc file stored in your home directory. Once you authenticate the first time, the credentials are saved locally so you do not need to enter them again.

Search for NISAR Data¶

1. Open the NASA Earthdata plugin from the menu.

2. Optionally add a basemap (e.g., Google Satellite) for spatial reference.

3. In the search box, type nisar and press Enter.

4. Select a data product from the dropdown. For this tutorial, try:

   • Level 2 GCOV (geocoded polarimetric covariance) for high-resolution SAR imagery

   • Level 3 for derived products like soil moisture

5. Click Use Map Extent to limit the search to the current map view, or leave it to search globally.

6. Adjust the date range if needed. Since sample data is limited, a broad date range (within the past year) works well.

7. Click Search.

The search results appear as footprints on the map and in a list below. Click any result to highlight its footprint in yellow and zoom to it. The list shows file sizes, which can range from under 1 GB to nearly 7 GB depending on the product and coverage area.

Download Data¶

1. Select the data product you want from the search results.

2. Click Download (or Download Specific Rows for individual files).

3. Choose a download directory (e.g., your Downloads folder).

4. Wait for the download to complete. Larger files may take several minutes.

The downloaded files use the .h5 (HDF5) format.

Convert H5 to NetCDF for Visualization¶

QGIS can open H5 files, but the georeferencing information is not preserved correctly. If you drag an H5 file directly into QGIS, the data layer will appear at coordinates 0,0 in the middle of the ocean instead of its actual location.

The fix is simple: rename the file extension from .h5 to .nc (NetCDF). The underlying data format is compatible, and QGIS reads the georeferencing correctly from NetCDF files.

1. Select the .h5 file in your file manager.

2. Copy and paste the file (or simply rename it).

3. Change the extension from .h5 to .nc.

Now drag the .nc file into QGIS. Select the data layer you want to visualize (e.g., a specific polarization band for Level 2 data, or soil moisture for Level 3 data) and click Add Layer. The data should overlay correctly on the map within the expected footprint.

Adjust the Visualization¶

The data may appear very dark initially because the default color stretch does not match the data range. To fix this:

1. Double-click the layer to open Layer Properties.

2. Go to the Symbology tab.

3. Under Min/Max Value Settings, change the method to Cumulative Count Cut (which uses percentiles to set the display range).

4. Click Apply.

The data should now display with much better contrast, revealing the spatial patterns in the SAR imagery.

For Level 2 GCOV data, the resolution is approximately 20 meters, providing detailed views of surface features. For Level 3 soil moisture data, you can identify spatial patterns where brighter areas represent higher soil moisture values and darker areas represent lower values. Urban areas may appear as no-data zones since soil moisture retrieval does not apply there.

Compare Datasets with the Swipe Tool¶

QGIS has swipe plugins (such as MapSwipe) that let you compare two layers side by side. This is useful for comparing SAR data against a satellite basemap:

1. Install a swipe plugin from the QGIS Plugin Manager.

2. Select the SAR data layer and the basemap layer.

3. Activate the swipe tool to slide between the two layers interactively.

Export to GeoTIFF¶

If you need to share the data or do further processing, you can export the layer to GeoTIFF:

1. Right-click the layer in the Layers panel.

2. Select Export > Save As.

3. Choose GeoTIFF as the format.

From there, you can convert to Cloud-Optimized GeoTIFF (COG) for web hosting, or process the data further with Python or other tools.

Resources¶

• NASA Earthdata QGIS Plugin: github.com/opengeos/qgis-nasa-earthdata-plugin

• NISAR Data User Guide (ASF): nisar-docs.asf.alaska.edu

• NISAR Mission: nisar.jpl.nasa.gov

• NASA Earthdata: earthdata.nasa.gov

This tutorial covers the basics of getting started with NISAR data. As more data products become available after the calibration phase, I plan to create additional tutorials exploring specific applications like ice movement analysis and vegetation monitoring. If you run into any issues with the plugin, feel free to open an issue on the GitHub repository.