EO·Atlas
SAR backscatter imaging
Synthetic-aperture radar amplitude imaging: measures the surface normalized radar cross-section (sigma-nought) at high spatial resolution, day-night and cloud-independent. The base SAR sensing method underlying ocean wind retrieval, wave-mode spectra, flood mapping, and change detection.
SAR backscatter imaging is the base active-radar method for all-weather surface imaging. It uses a synthetic-aperture radar payload to form calibrated amplitude images of surface backscatter at metre-to-tens-of-metres scale, independent of daylight and most cloud conditions.[1] It serves flooding, sea ice, oil spill screening, maritime surveillance, and the downstream SAR wind and wave methods that start from SAR image products.
The method needs radiometric calibration, incidence-angle metadata, polarisation metadata, and enough antenna, power, downlink, and processing margin for imaging modes. Interpretation fails when geometry dominates the target signal: layover, shadow, foreshortening, speckle, wind roughening, wet-surface effects, and incidence-angle variation can all look like real surface change unless the product is terrain-corrected and normalised.
Demonstrated implementations include Sentinel-1 C-SAR, ALOS-2 PALSAR-2, and ICEYE X-band SAR. C-SAR provides C-band SAR modes including Interferometric Wide swath imaging at 250 km swath and 5 x 20 m ground resolution.[1] PALSAR-2 adds L-band SAR with spotlight, stripmap, and ScanSAR modes plus single, dual, compact, and full-polarisation options.[2] ICEYE provides X-band SAR imaging modes for repeat commercial monitoring, with sub-metre tasking modes and day-night, all-weather operation.[3]
SAR ocean products can provide local ocean surface velocity context, but the canonical row is broader SAR backscatter rather than a Doppler-current method.
- C-SAR
via Sentinel-1A
Sentinel-1 C-SAR is an operational C-band synthetic-aperture radar imaging payload; this edge covers calibrated SAR amplitude/backscatter imagery as the base acquisition method.
- PALSAR-2
via ALOS-2
ALOS-2 PALSAR-2 is an L-band synthetic-aperture radar imaging payload; this edge covers SAR amplitude/backscatter imaging in L-band.
- ICEYE X-band SAR
via ICEYE-X1
ICEYE X-band SAR provides operational SAR imaging modes; this edge covers amplitude/backscatter SAR imagery rather than interferometric or polarimetric derivatives.
- MONITORED AI
MONITORED AI processes SAR imagery (Sentinel-1, TerraSAR-X, PAZ, ICEYE) with bounding-box object detection to identify vessel positions; pipeline includes background suppression, composite geo-image creation, and two detection models (large/medium + small non-metallic vessel)
- MetaSAR-C
WaddenSAR 2022 and SARSense campaigns confirmed C-band SAR backscatter imaging
- MetaSAR-L
BelSAR 2018 Belgium campaign demonstrated L-band SAR backscatter imaging over agricultural fields
- MetaSAR-X
- Ground SAR Processor
- Guardian
Guardian X-band SAR in stripmap/spotlight mode; defence ISR application, not EO
Measures millimetre-scale ground surface displacement by comparing phase differences between repeat SAR passes; good for subsidence, earthquake deformation, and volcanic monitoring.
Decomposes backscatter into scattering mechanisms (surface, double-bounce, volume) using multi-polarisation data; good for forest structure estimation, urban mapping, and soil moisture retrieval.
Real-aperture radar that measures normalized radar cross-section from multiple azimuth angles to retrieve ocean surface wind vectors (speed and direction) over wide swaths at ~12-25 km resolution. Distinct from SAR: non-imaging, coarse-resolution, optimised for global daily wind fields.
- [1]Sentinel-1 Instrumentagency doc2026-06-08
- [2]ALOS-2 Sensor: PALSAR-2agency doc2026-06-08
- [3]ICEYE SAR dataoperator engineering2026-06-08
Edited from public sources. Last reviewed date pending by SpectraWorks editorial. See the data dictionary for field definitions.