Aeolus+Processes
In August 2018, after nearly two decades of development, the European Space Agency launched the Aeolus mission, https://www.esa.int/Applications/Observing_the_Earth/FutureEO/Aeolus, the first spaceborne observations of the global wind profiles. Even though Aeolus was designed as a demonstrator mission, its horizontal line-of-sight (HLOS) winds have been assimilated in all major global numerical weather prediction (NWP) models with positive impact on the forecasts. For example, the evaluation of Aeolus forecast impact in the ECMWF operational system and in the observing system experiments show that Aeolus' impact on short-range forecasts has a similar magnitude to that of other satellite observations, this despite Aeolus accounting for less than 1% of the assimilated observations. The key question for scientific exploration is why Aeolus, despite its random errors being 2-3 times greater (in the Rayleigh channel) than the background errors and that of radiosondes, is beneficial for NWP in every global weather forecasting centre? What atmospheric processes and which shortcomings of the NWP models are being improved by Aeolus winds? These and other questions are now investigated in an ESA-funded project in collaboration with ECMWF.