Sentinel-1 Bursts: ASF services offering direct access inside an SLC

Sentinel-1 is a C-band SAR satellite operated by the European Space Agency (ESA) that provides regular coverage of the entire globe on a 12-day repeat cycle. The Alaska Satellite Facility (ASF) provides a mirror archive of this dataset in the cloud that is free and open. Sentinel-1 uses the Terrain Observation with Progressive Scans SAR (TOPSAR) technique that acquires data in small bursts, which are then aggregated into frames that a user downloads. A typical Single-Look Complex (SLC) product consists of 25-30 bursts. However, Sentinel-1 SLC products are often 4 GB or larger in size, and cover an area of more than 250 square kilometers. A user doing interferometric (InSAR) time series analysis will often need to download many scenes, and because of their size, this will require significant processing time and local storage. Moreover, SLC framing is not always consistent over successive acquisitions, meaning often multiple adjacent frames are needed, complicating the process of identifying scenes.

As part of ASF's mission to make Sentinel-1 data easier to use, ASF now offers the ability to download SLC bursts directly. Most InSAR users have an interest in areas covered by only a handful of busts, so allowing download and processing by burst has the potential to cut the download volume and processing times by more than an order of magnitude. This saves the user time and effort, as well as requiring much less local compute infrastructure. In addition, bursts with the same ID and swath number represent measurements at the exact same location on the Earth, allowing for easier generation of co-located time-series image stacks.

This poster will provide a technical overview of bursts, including the new identification scheme released by ESA, as well as describing the interfaces that ASF now offers that allow searching for and downloading data directly by burst, including information on the necessary metadata that a user will need in order to process locally.