Satellite Winds

About the data sets

Satellite SAR wind fields

Wind fields displayed on this web site are retrieved by DTU Wind Energy from satellite Synthetic Aperture Radar (SAR) observations over the ocean.

Spatial and temporal coverage

Our SAR wind archive covers the seas around Europe and other selected seas around the world during the years 2002 to present. There is a gap in the data series from April 2012 to April 2014 due to a lack of European satellite SAR data coverage.

Data delivery

Wind fields are typically available on this web site within a day after data acquisition by the satellites. Although we process raw satellite observations to wind fields as quickly as possible, we cannot always guarantee delivery on the acquisition date.

Units and conventions

The SAR wind maps show Equivalent Neutral Wind speeds at 10 m above the sea surface. Wind directions are expressed in degrees (0-360) from North using the meteorological convention (i.e. the direction that the wind is coming from). Wind directions displayed on the maps are obtained from ancillary data. We use wind directions from a global model per default.

What can be seen?

Thanks to a high spatial resolution, SAR imagery is very suitable for observation and characterization of mesoscale meteorological phenomena such as island and mountain wakes, gap flows, and synoptic fronts (C. B. Hasager et al., 2015). An extensive gallery of images and interpretations of meteorological phenomena can be found in Beal et al. (2004). Effects of large man-made structures such as offshore wind farms and platforms can also be observed in great detail (C. Hasager et al., 2015).

Examples

The examples below show some of the wind phenomena which can be detected from SAR.

Example of Mountain gravity waves

Example of Mountain gravity waves
Wind field from Sentinel 1A showing mountain gravity waves over Scotland. April 20, 2017 at 06:29 UTC.

Example of Gap flows

Example of Gap flows
Wind field from Sentinel 1B showing gap flow through the Strait of Gibraltar. March 18, 2017 at 17:13 UTC.

Example of Island wakes

Example of Island wakes
Wind field from Sentinel 1B showing island wakes in the Aegean Sea with northeasterly winds. April 18, 2017 at 04:22 UTC.

Example of Wind farm wakes

Example of Wind farm wakes
Wind field from Sentinel 1A showing wakes of large offshore wind farm in the North Sea with westerly winds. May 28, 2017 at 17:25 UTC.

Satellites and sensors

Wind fields displayed on this site are primarily retrieved from SAR data provided by the European Space Agency (ESA). A smaller collection of SAR scenes from the German Aerospace Center (DLR) can also be found in the archive. The SAR scenes are acquired by polar-orbiting satellites, which circumvents the Earth at altitudes on the order of 400-700 km.

Sentinel-1

ESA’s Sentinel-1 mission is a constellation of two satellites, each with a C-band SAR on board. Sentinel-1A was launched on 3 April 2014 and Sentinel-1B on 25 April 2016. Both sensors are operating at present. Over the ocean, Sentinel-1 data acquisition is performed in Interferometric Wide swath (IW) or Extra Wide swath (EW) mode according to pre-defined observation scenario.

ENVISAT

ESA’s ENVISAT mission was launched in 2002 and its data acquisition was terminated in April 2012. ENVISAT carried an Advanced Synthetic Aperture Radar (ASAR) operating in C-band with several different modes. The majority of Envisat ASAR scenes in this archive have been acquired in Wide Swath mode (WSM) or Global Monitoring mode (GMM) with a swath width of 400 km and variable lengths. The Image mode (IM) and Alternating Polarisation mode (APP) are suitable for ocean wind retrieval over smaller areas due to their swath width of 100 km. This archive holds a limited collection of processed data based on these modes.

TerraSAR-X

The German Aerospace Center (DLR) operates the TerraSAR-X mission since January 2008. Data are processed over selected sites as part of scientific projects and the resulting wind fields are displayed on this site. TerraSAR-X is and X-band SAR sensor with different modes. This archive contains scenes acquired in ScanSAR, Stripmap, and Spotlight mode.