Wide-Area Analysis-Ready Radar Backscatter Composites

Abstract

The benefits of composite products are well known to users of data from optical sensors: cloud-cleared composite reflectance or index products are commonly used as an analysis-ready data (ARD) layer. No analogous composite products are currently in widespread use that is based on spaceborne radar satellite backscatter signals. Here, we present a methodology to produce wide-area ARD composite backscatter images. They build on the existing heritage of geometrically and radiometrically terrain corrected level 1 products. By combining backscatter measurements of a single region seen from multiple satellite tracks (incl. ascending and descending), they are able to provide wide-area coverage with low latency. The analysis-ready composite backscatter maps provide flattened backscatter estimates that are geometrically and radiometrically corrected for slope effects. A mask layer annotating the local quality of the composite resolution is introduced. Multiple tracks are combined by weighting each observation by its local resolution, generating seamless wide-area backscatter maps suitable for applications ranging from wet snow monitoring to land cover classification or short-term change detection.

Drying conditions in Switzerland – indication from a 35-year Landsat time-series analysis of vegetation water content estimates to support SDGs

“…Sentinel-2; Landsat-5, -7, -8) and radar (e.g. Sentinel-1) satellite EO data (Giuliani et al, 2017;Giuliani, Chatenoux, Honeck, & Richard, 2018;Small, Rohner, Miranda, Rüetschi, & Schaepman, 2021;Truckenbrodt et al, 2019). The SDC facilitates national-scale analyses of large volume of spatially aligned and consistently calibrated satellite EO data.…”

A Sentinel-1 Backscatter Datacube for Global Land Monitoring Applications

“…The latter representation of backscatter is superior to the former in mountainous regions because it accounts for terrain-related changes in the radar illumination area. This minimises radiometric terrain effects, which is beneficial to SAR applications particularly over undulating and rugged terrain [21,22]. Therefore, the Committee of Earth Observation Satellites (CEOS) has selected γ • rt f over σ • in its ARD standard for normalised radar backscatter.…”

Cloud Optimized Raster Encoding (CORE): A Web-Native Streamable Format for Large Environmental Time Series

“…For example, scientists at the Swiss Federal Research Institute WSL aspire to provide open and easy access to modified Copernicus data for Switzerland (www.copernicus.eu, accessed on 10 August 2021), with a special interest in contemporary high-resolution data of the Sentinel missions [9]. Cloud-cleared composite reflectance or index products provided as analysis ready data (ARD) will relieve users from costly preprocessing steps [10,11]. The data volume produced by the Sentinel missions is quite significant, with one single compressed (.zip) tile having around 1 GB.…”