Aeolus: ESA’s wind mission. Status and future challenges

The European Space Agency (ESA)’s wind mission, Aeolus, was launched on 22 August 2018. It is a member of the ESA Earth Explorer family and its main objective is to demonstrate the potential of Doppler wind Lidars in space for improving weather forecast and to understand the role of atmospheric dynamics in climate variability. Aeolus carries a single instrument called ALADIN: a high sophisticated spectral resolution Doppler wind Lidar which operates at 355 which is the first of its kind to be flown in space.

Aeolus provides profiles of single horizontal line-of-sight winds (primary product) in near-real-time (NRT), and profiles of atmospheric backscatter and extinction. The instrument samples the atmosphere from about 30 km down to the Earth’s surface, or down to optically thick clouds. The required precision of the wind observations is 1-2.5 m/s in the troposphere and 3-5 m/s in the stratosphere while the systematic error requirement be less than 0.7 m/s. The mission spin-off product includes information about aerosol and cloud layers. The satellite flies in a polar dusk/dawn orbit (6 am/pm local time), providing ~16 orbits per 24 hours with an orbit repeat cycle of 7 days. Global scientific payload data acquisition is guaranteed with the combined usage of Svalbard and Troll X-band receiving stations.

After almost five years in orbit and despite some performance issues related to its instrument ALADIN, Aeolus has achieved all its scientific objectives and gone beyond its original designed life-time in space. Positive impact on the weather forecast has been demonstrated by multiple NWP centres world-wide, with four European meteorological centres now are assimilating Aeolus winds operationally, paving the way to its successor: EPS-Aeolus. Aeolus data is being used with success over a number of innovative research streams with growing scientific impact on literature.

The status of the Aeolus mission will be presented including the last main challenge to re-enter the satellite from space with an assisted scenario instead of an uncontrolled one, as initially foreseen by design.