A Consolidated Assessment of the Impact of Aeolus Winds in Numerical Weather Prediction at ECMWF
The Aeolus ESA Earth Explorer mission’s Level-2B horizontal line-of-sight (HLOS) wind product has been operationally assimilated in ECMWF’s global data assimilation system for over three years due to its positive impact on forecast skill, which is a great success for a technology demonstration mission.
We shall present a consolidated assessment of ECMWF’s NWP impact from ECMWF, now that the mission is in its final year. Observing system experiments have been performed using reprocessed datasets covering 2018 to 2020 and NRT data for more recent periods. We have many long-period OSEs which help to identify the similarities in the patterns of forecast improvement from Aeolus in different years – giving increased confidence in that improvement. In 2018 and 2019 Aeolus had periods of decent quality winds due to reasonable signal-to-noise ratio. The lower noise in such periods results in larger magnitude positive impact. Such periods suggest the minimum impact one could expect from an operational EUMETSAT Doppler Wind Lidar follow-on mission (EPS-Aeolus), for which significantly better SNR and vertical resolution is sought. Forecast Sensitivity Observation impact results will also be presented. FSOI and OSE impact varied significantly during the mission depending on the signal levels. This allows some extrapolation to what should be possible with EPS-Aeolus expected levels of random error. At its best Aeolus FSOI was amongst the top performers per satellite instrument at ECMWF (reaching 4-5%).
If time permits, then some of the work on the monitoring and improving the L2B wind retrievals as part of the ESA funded Aeolus DISC will be presented.
