Radar scatterometry

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]