Vertex¶
Vertex is ASF’s web-based method to search for NISAR data products. Because search parameters for SAR differ from other types of Earth observation data, it can be helpful to use a platform that is tailored specifically for SAR data. This is useful for those who are less familiar with SAR data products and may need more guidance to find the appropriate data products for their use case.
Using Vertex to Access NISAR Data¶
1. Search for NISAR data¶
Navigate to Vertex and set the Search Type to Geographic Search and select NISAR from the Dataset menu. Press Search to explore search results.
Figure 1:Click on the “Dataset” button and select “NISAR” to search for NISAR products.
2. Filter for desired products¶
To search for a specific geographic region, click on the left-most Area of Interest button to choose to draw a point, line, polygon, box, circle, or to upload a geospatial file. Toggle on drawing mode to draw a region of interest, then press Search to update the search for the new region of interest.
Figure 2:Choose a shape and draw an area of interest for a geographic search.
To search for products in a specific date range, open the Filters panel and specify a start and end date to define the search range.
Figure 3:The option to filter by date pops up after clicking on “Filters”
NISAR-specific filters are available to more precisely search for NISAR data products. Refer to the Vertex Getting Started User Guide for a comprehensive list of filters and search options.
Figure 4:NISAR-specific filters in Vertex.
Product Filters are listed in Table 1. Science Products are organized by product level, and multiple selections are allowed. For a complete list of NISAR products, including detailed descriptions and specifications, refer to Data Products Overview.
Table 1:Product Filters for NISAR Products
| Product Filters | Description |
|---|---|
| Science Product | Specific product type, grouped by product level. Multiple selections allowed. |
| Product Configuration | Specific processing pipelines. Multiple selections allowed. |
Observational Filters allow users to refine search results by polarization, direction, instrument, frame coverage, and/or range bandwidth, as described in Table 2. For information about NISAR bands, frequencies, and polarization, see NISAR Instrumentation. Note that only L-band data are available through Vertex. S-band data are provided through ISRO’s Bhoonidhi.
Table 2:Observational Filters for NISAR Products
| Observational Filters | Description |
|---|---|
| Main Band Polarization | Frequency A polarizations. Multiple selections allowed. |
| Side Band Polarization | Frequency B polarizations. Multiple selections allowed. |
| Direction | Orbit direction (ascending, descending). |
| Instrument | Currently, only L-Band SAR available. |
| Frame Coverage | Full or Partial frame coverage. |
| Range Bandwidth | Range bandwidth in MHz. Multiple selections allowed. |
| Joint Observation Only | Toggle on for simultaneous L- and S-Band acquisitions. |
Users can also search by Track and Frame. Note that “Track” is also known as “Path” or “Relative Orbit” for other satellite missions, such as Sentinel-1. Searching for a specific track and frame will return scenes that align consistently over a specific area. The NISAR track-frame map for available NISAR data is available on the NISAR Mission website.
3. Download data¶
Data are free and available to download through Vertex. Once the desired scene is selected, a list of files will appear on the right-hand side of the screen (or below the scene details on a narrow browser window). The HDF5 file, listed first, contains the science data and imagery. To learn more about HDF5 files, see What is HDF5?.
Click the download icon next to the HDF5 file name to save to your computer. You will be prompted to sign in with your Earthdata Login (EDL) account if you have not already. For more information about EDL accounts, see Accessing Data Using EDL Accounts.
Figure 5:All product files associated with a GCOV product. The HDF5 file, listed first, contains the science data and imagery, and can be downloaded directly by clicking the download icon, circled in red.