Burst-Based InSAR for Sentinel-1 On Demand

 Single Look Complex  (SLC) data is required to generate interferograms from Sentinel-1 Synthetic Aperture Radar (SAR) data. Most InSAR processing uses the  Interferometric Wide Swath (IW)  SLC products produced by the European Space Agency (ESA), which package individual radar bursts together into larger scenes. These IW SLC products include three sub-swaths, each containing many individual burst SLCs.

ASF has developed a method of  extracting the individual SLC bursts  from IW SLC products, which allows users to process interferograms for each individual SLC burst. While ASF has offered  InSAR On Demand  processing for Sentinel-1 IW products for many years, we now also offer  burst-based InSAR products On Demand !

Working at the burst level of the Sentinel-1 SLC data provides a couple key benefits:

1. Bursts are consistently geolocated through time The coverage of a burst is the same for every orbit of the satellite, so you can be confident that every burst with the same  Full Burst ID  in a stack of acquisitions will cover the same geographic location. In contrast, the framing of the IW SLCs is not consistent through time, so when using IW SLCs as the basis for InSAR, scene pairs do not always fully overlap.

2. Bursts cover a smaller geographic area IW SLC products are extremely large, and, in many cases, only a small portion of the image is of interest. You can process only the bursts that cover your specific area of interest, which significantly decreases the time and cost required to generate InSAR products.

Refer to the  Sentinel-1 Bursts tutorial  to learn more about how  ASF extracts burst-level products  from Sentinel-1 IW and EW SLCs.

The Sentinel-1 Burst InSAR products are generated using the Jet Propulsion Laboratory's  ISCE2 software . ASF is committed to transparency in product development, and we are pleased to be able to offer an InSAR product that leverages open-source software for processing.

For those who would prefer to work at the scale of a full IW SLC, our original  On Demand InSAR  products are still available. These products have a larger footprint, and are generated using  GAMMA software .

The process of ordering burst-based InSAR is very similar to ordering  On-Demand InSAR for full Sentinel-1 SLC scenes . The key difference is that you search for Sentinel-1 bursts by selecting the S1 Bursts dataset rather than searching the standard Sentinel-1 dataset.

On Demand users are given an allotment of 10,000 credits per month to use for processing jobs, and each type of On Demand job costs a different number of credits, as shown in the  Credit Cost Table .

More information about the credit system is available  here . If you have any questions or comments, contact ASF at uso@asf.alaska.edu.

This tutorial will focus on using ASF's Vertex Data Search to find and submit burst InSAR jobs, but for those who are interested in using a programmatic approach, the  HyP3 Python SDK and API  offer support for burst-based InSAR processing.

A Burst InSAR job is submitted for On-Demand processing as a pair of Sentinel-1 bursts to be used to generate the interferogram. There are currently two methods of selecting and submitting scene pairs in Vertex: the  Baseline  and  SBAS  search interfaces.

The  Baseline  tool is most appropriate for selecting specific individual pairs to use for interferometry. This is often useful when generating an interferogram for a discrete event, such as an earthquake. Once you find a good acquisition to use as the reference scene, use the Baseline tool to find appropriate secondary scenes.

The  SBAS  tool is designed to compile a series of many InSAR pairs that covers a long period of time. This time series approach is often used when monitoring long-term processes such as groundwater subsidence or magma chamber dynamics.

In both cases, you will start with a  Geographic Search  in Vertex to find a reference scene that you want to use for InSAR. You can then select the  Baseline tool  to find another scene to pair with it to generate a single interferogram, or the  SBAS tool  to compile a time series of InSAR pairs that cover the same footprint as the reference scene.

Scroll through the tutorial below to learn how to find Sentinel-1 bursts in ASF's Vertex Data Search portal

Use the navigation bar at the top of the screen to access the Baseline or SBAS tutorials directly if you're already familiar with the Vertex search interface

Once you've selected a reference burst using the Geographic Search in Vertex, you'll need a secondary burst to match with it to generate an interferogram. Because bursts have the same footprint on each pass, bursts acquired on different dates with the same Full Burst ID will always overlap well.

The  perpendicular baseline  indicates the distance between the imaging platform locations during the two acquisitions. The phase difference measurements will be better if the scenes are acquired from very similar locations in space. The Baseline tool finds and lists all the bursts that are suitable for pairing with the reference burst to generate an interferogram.

Scroll through the tutorial below to learn how to use the  Baseline Tool  to pick InSAR pairs for processing

Time series analysis of InSAR products is often used to monitor landscape or geophysical processes, determine rates of change, gain insight into the characteristics of deformation, and correct for atmospheric impacts or other noise signals. One common method for time series analysis is the Small BAseline Subset (SBAS) approach.

SBAS uses a series of many interferograms generated from SAR images acquired over an extended time period, with each individual InSAR pair having a relatively short time interval between acquisitions. A range of short baselines are used, allowing for pairs to overlap each other, and for each reference scene to be paired with multiple secondary scenes.

The  SBAS Tool  in Vertex assists users in compiling a list of burst pairs suitable for use in SBAS analysis.

Scroll through the tutorial below to learn how to use the  SBAS tool  to find and submit a time series of InSAR burst pairs for On Demand processing

Click the arrows or swipe to move through the slideshow, which demonstrates the steps involved in working with Custom Pairs

Set processing parameters and submit jobs for processing

Search for your On Demand products, check processing status, view browse images, resubmit expired jobs

Download On Demand products individually or in bulk

The Burst InSAR products are downloaded in zip archives, which include GeoTIFFs of the interferograms, ancillary files that can be used for reference or further processing, and accompanying documentation. To explore a sample product, click the button below to download the product zip file for the example featured in this tutorial.

If you are new to ASF's On Demand Burst InSAR products, open the README file included in the zip file to find out more information about the files included in the product package. It can be read either as a text file or in a Markdown viewer/editor.

Refer to our  Sentinel-1 Burst InSAR Product Guide  for additional information on the On Demand Burst InSAR processing workflow and options, files included in the product package, and guidance for usage.

Updated 21 March 2025

Support for submitting multi-burst InSAR jobs directly in Vertex is currently under development. Stay tuned for updates!

Sentinel-1 SLC bursts from along the same path can be merged together to generate a single interferogram, which is very useful when the area of interest you'd like to observe spans multiple bursts or crosses Sentinel-1 IW SLC boundaries.

Multi-burst InSAR uses the  burst2safe Python package  to package sets of up to 15 contiguous, along-track bursts into a single pair of reference and secondary files in ESA's  SAFE file format . This pair of SAFE files is then used to generate the interferogram.

You are now able to submit multi-burst jobs via the  HyP3 API  and  Python SDK , though multi-burst processing is not yet supported in  Vertex . Refer to the  Sentinel-1 Burst InSAR Product Guide  for more information on multi-burst InSAR.