EO·Atlas
Radar scatterometry
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.
Radar scatterometry is the operational coarse-resolution radar method for ocean surface wind vectors. It measures normalised radar backscatter from multiple azimuth and incidence-angle looks, then retrieves wind speed and direction with a geophysical model function rather than forming a fine-resolution image.[1] It serves ocean-surface winds, numerical weather prediction, marine forecasting, and storm monitoring where wide swath and frequent coverage matter more than local detail.
The method needs a dedicated real-aperture scatterometer geometry, stable calibration, multi-look ambiguity removal, land and ice masks, and quality control against rain and coastal contamination. It fails as a fine coastal mapper: conventional products are around 12.5-25 km, rain can bias wind retrievals, and land proximity or sea ice can contaminate the wind vector cell.[2]
Demonstrated implementations include ASCAT on Metop and SeaWinds on QuikSCAT. OSI SAF ASCAT products provide operational Level-2 wind direction and speed from Metop ASCAT at 25 km sampling, with a long operational series beginning in 2007.[2] QuikSCAT's SeaWinds instrument was a microwave radar designed for ocean near-surface wind speed and direction and provided global ocean coverage every two days.[3]
Scatterometers measure wind stress that helps estimate wind-driven surface-current components.
- HY Scatterometer
via HY-2B
HSCAT is a Ku-band scatterometer flown on HY-2B for near-surface ocean wind vectors.
- CFOSAT Scatterometer (SCAT)
via CFOSAT
CFOSAT SCAT is a Ku-band scatterometer for sea-surface wind measurements; WMO records it as inactive after degradation.
- HY-2C HY Scatterometer
via HY-2C
HY-2C HSCAT is the Ku-band scatterometer payload.
- OSCAT-3 Scatterometer
via Oceansat-3
OSCAT-3 / SCAT-3 is the Ku-band scatterometer payload on Oceansat-3.
None on record.
Measures millimetre-scale ground surface displacement by comparing phase differences between repeat SAR passes; good for subsidence, earthquake deformation, and volcanic monitoring. Single-pass interferometry from a SAR pair also measures topographic height and underlies global digital elevation models such as Copernicus DEM.
Decomposes backscatter into scattering mechanisms (surface, double-bounce, volume) using multi-polarisation data; good for forest structure estimation, urban mapping, and soil moisture retrieval.
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.
- [1]ASCAT - Advanced Scatterometeragency doc-2026-06-08
- [2]Metop-C ASCAT 25 km Windsagency doc-2026-06-08
- [3]Quick Scatterometeragency doc2010-01-072026-06-08
Edited from public sources by SpectraWorks editorial. See the data dictionary for field definitions.
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Plain text
Radar scatterometry. EO-Atlas, SpectraWorks B.V. https://eo-atlas.org/topics/methodologies/radar-scatterometry (CC BY 4.0)
BibTeX
@misc{eoatlas:topics:methodologies:radar-scatterometry,
title = {Radar scatterometry},
author = {{EO-Atlas}},
publisher = {SpectraWorks B.V.},
note = {CC BY 4.0},
url = {https://eo-atlas.org/topics/methodologies/radar-scatterometry}
}