Example of Aeolus Rayleigh-clear Level-2B HLOS winds
Introduction to Aeolus
Aeolus is the fifth satellite in the Living Planet Programme of the European Space Agency, after being launched on 22 August 2018. The mission's objective is to provide profiles of high-quality wind observations from the surface to the lower stratosphere, using a Doppler wind lidar (DWL) instrument (known as ALADIN) in a near-polar sun-synchronous, dawn-dusk orbit at around 320 km altitude. The wind information is the horizontal line-of-sight (HLOS) component, in the direction perpendicular to the satellite's velocity. The mission has surpassed its minimum lifetime of three years.
ECMWF is contracted by ESA to develop, in collaboration with KNMI, DLR and other partners of the Aeolus DISC the Aeolus Level 2B/C (L2B/C) processing software i.e. the wind retrieval. ECMWF generates the L2B products operationally and in NRT via the L2/Met PF (Level-2/Meteorological Processing Facility; a part of the mission's Ground Segment), and disseminates the products to ESA for further distribution to users. ECMWF also convert the L2B Earth Explorer format products to a WMO approved BUFR format which is provided to EUMETSAT for further distribution to the NWP/research community via the GTS and EUMETCast.
ECMWF have operationally assimilated the Aeolus L2B wind observations in ECMWF's global NWP (Numerical Weather Prediction) model since 9 January 2020, since they were proven to improve forecast skill. Aeolus winds have a positive impact on analysis and forecast quality, particularly in the tropics and polar areas, particularly where conventional wind profiles are absent.
Given that ALADIN is a High Spectral Resolution Lidar, it is also possible to derive information on atmospheric composition: cloud and aerosol optical properties (particle backscatter and extinction coefficients, via the Level-2A product).
Further information and publications on Aeolus:
- See ESA's website on Aeolus
- Aeolus on twitter
- QJRMS article about the NWP impact of Aeolus at ECMWF: https://doi.org/10.1002/qj.4142
- A conference proceedings article on some of the demonstrated scientific benefits of Aeolus: https://ieeexplore.ieee.org/abstract/document/9554267
- ECMWF web articles about ECMWF operationally assimilating Aeolus winds:
- An ECMWF Technical Memorandum on Aeolus: https://www.ecmwf.int/en/elibrary/19538-nwp-impact-aeolus-level-2b-winds-ecmwf
- Aeolus was launched on 22 August 2018; this website provided a log of progress on the satellite up until launch: https://aeolusweb.wordpress.com/
- A CAL/VAL rehearsal workshop took place in March 2017 and the presentations can be found via this web page: http://www.aeolus-calval-2017.org/
- CAL/VAL rehearsal L2B and L2C datasets are available here
- Aeolus CAL/VAL and Science workshop 2019
- Aeolus CAL/VAL and Science workshop 2020
- Aeolus 3rd anniversary conference in 2022
- Documents prepared for ESA regarding the L2B/C processing are available here; which might be useful to help understand the L2B products
- Browse the available Aeolus data from ESA's ground segment
- Automated Aeolus L2B data quality monitoring at ECMWF
- Monthly Aeolus L2B quality reports by ECMWF (search for Aeolus)
- An introductory talk on Aeolus winds from the EUMETSAT/ECMWF NWP-SAF Satellite data assimilation training course: SAT_TC_Aeolus_winds_MR_v2022.pptx
- An introductory talk about Aeolus L2B winds (possibly now obsolete): Aeolus_L2B_winds.pptx
The L2B processing software
KNMI and ECMWF develop the Aeolus Level-2B wind retrieval software, the main output of which are HLOS wind observations, which are suitable for use in NWP and meteorological research. Refer to the Algorithm Theoretical Basis document for information about the algorithms (see documentation links below).
Downloading the L2B processing software and documentation
- The Aeolus Level-2B/C processing documentation (including the Software Release Note, the Algorithm Theoretical Basis and the Input/Output Data Definitions Interface Control documents) and associated datasets (needed to test the success of the installation) is available for download: Download Aeolus L2B/C documentation and datasets
- The source code can be freely downloaded from from our website (upon acceptance of the licence terms): Download Aeolus L2B processor package
- News on updates to the software, e.g. planned deliveries, is provided here
- Aeolus L2B winds have a WMO approved BUFR template:
- Some guidance for NWP users on the L2B BUFR data
An example of real Aeolus L2B HLOS winds, from an orbit just to the west of hurricane Dorian on 1 September 2019: