Atmospheric Wind Observation

Atmospheric wind observation from space addresses a longstanding gap in global meteorology: the distribution of wind at multiple levels throughout the atmosphere, and at the ocean surface, cannot be measured adequately by conventional in-situ methods alone. Radiosondes and aircraft wind reports provide accurate localised profiles but cover only a fraction of the globe, leaving the open ocean, the southern hemisphere, and the tropical mid-troposphere chronically undersampled. These gaps propagate into numerical weather prediction (NWP) models, reducing forecast accuracy in data-sparse regions and degrading the quality of climate reanalyses that depend on a globally consistent wind record.

Spaceborne instruments address this gap through several complementary physical approaches, each sensitive to a different wind-bearing signal.

Doppler wind lidar (DWL) measures the frequency shift of backscattered ultraviolet laser pulses from aerosols and molecules, yielding direct line-of-sight wind profiles from the surface up to approximately 30 kilometres. ESA Aeolus, which carried the ALADIN DWL instrument and operated from 2018 until 2023, was the first spaceborne demonstration of this technique and produced measurable improvements in NWP forecast skill when its wind profiles were assimilated at ECMWF. ^[1][2] A follow-on mission is in development to continue and expand the profile record.

Radar scatterometry infers ocean-surface wind vectors from the normalised radar cross section of centimetre-scale capillary waves. C-band and Ku-band radar beams illuminate the sea surface at multiple azimuth angles, and a geophysical model function relates the backscatter pattern to near-surface wind speed and direction. Instruments in operational service include the ASCAT scatterometers on the MetOp series of satellites. ^[3] Scatterometers also operate on the HY-2 and CFOSAT satellites. EUMETSAT's MetOp-SG constellation is planned to carry an advanced C-band scatterometer; its operational entry date had not been publicly confirmed at the time of last review.

Atmospheric motion vectors (AMVs) are proxy wind observations derived by tracking the displacement of clouds and water-vapour features between successive satellite images. Rather than measuring air motion directly, AMVs infer wind by assuming that a tracked feature moves with the local ambient flow. Geostationary meteorological satellites observe the same area every ten to fifteen minutes, producing dense AMV fields particularly in the tropics and mid-latitudes. ^[4] Research into three-dimensional AMV retrieval, using multi-angle or stereo observations, is extending the technique toward height-resolved wind vectors. ^[5]

Additional spaceborne approaches contribute to or are emerging for this problem, including passive microwave radiometry, SAR-derived ocean surface winds, GNSS reflectometry, Doppler cloud radar, and radio occultation.

This topic covers spaceborne meteorological wind measurement for NWP and forecasting. It is distinct from the wind-siting topic, which addresses land-surface terrain analysis and wind-resource mapping for siting wind energy installations.