ADM Aeolus – Measuring the wind from space with a laser for the first time

Aeolus is part of ESA's 'Living Planet' programme, for which Germany is the foremost partner and contributor. The Space Administration of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in Bonn manages the German contributions to ESA on behalf of the Federal Government: "The years-long, complex development of this laser system – which works in the ultraviolet spectral range – means that Europe has achieved a technological and scientific breakthrough," says Walther Pelzer, member of the DLR Executive Board. "I am delighted that German expertise from industry and science has not only paved the way for this breakthrough, but has also made a decisive contribution towards a ground-breaking prototype for future operational systems, thus supporting the plans of the World Meteorological Organization (WMO)."

With Aeolus, and the Aladin laser system in particular, medium-term weather forecasts – looking up to 15 days ahead – will see significant improvements: "Above all, an exact understanding of weather dynamics in the tropics and over the Pacific helps us to make more reliable predictions of severe and sudden storms at our latitudes," says Albrecht von Bargen, DLR coordinator of the German contributions to the analysis and processing of Aeolus data. Previously, weather services have had to base their predictions on comparatively sparse and localised wind data. There is little coverage of the oceans, Africa, South America and the polar regions. Many extreme weather events, such as hurricanes, which can cause extensive damage even in Germany and elsewhere in Europe, occur between the subtropics and the subpolar latitudes. The European Centre for Medium-Range Weather Forecasts (ECMWF) – run by European national meteorological services – will process the Aeolus data and make it available to the European national meteorological services. "As such, Aeolus fills a truly important gap," von Bargen says.

On board Aeolus, Aladin (Atmospheric laser doppler instrument) is based on lidar (light detection and ranging) technology, meaning the measurement of distances and atmospheric properties using laser light. "Aladin sends short UV light pulses to the Earth's surface. Using a telescope, the signals scattered by the molecules, clouds and dust particles are then detected again so that the duration of the radiation and its frequency can be evaluated. This allows us to derive global wind profiles, from the ground through to altitudes of 30 kilometres," explains Oliver Reitebuch from the DLR Institute of Atmospheric Physics in Oberpfaffenhofen. "We have demonstrated the technical and scientific capabilities using a lidar prototype over the course of several campaigns with our Falcon research aircraft." Even before the start of the satellite mission, DLR scientists were able to obtain measurement data using an instrument similar to Aladin, thus enabling them to demonstrate and test the recording of wind speeds. Following the launch of Aeolus, Reitebuch and his colleagues plan to continue with the aircraft-based measurements and fly beneath the satellite to validate the accuracy of its wind measurements.