AEOLUS-DISC

General project description

The Aeolus DISC (Data, Innovation, and Science Cluster) is an international expert consortium of research laboratories dedicated to the European Space Agency (ESA) Earth Explorer mission Aeolus. The Aeolus satellite was operated between 2018 and 2023 and carried the first UltraViolet (UV) Doppler Wind Lidar in space : Atmospheric LAser Doppler Instrument (ALADIN). Despite being initially designed to measure Earth’s wind on a global scale, the Aeolus mission also provided aerosol profiling around our planet up to 30 km altitude optimizing the High Spectral Resolution (HSR) capacity of ALADIN. This helps characterizing the optical properties of aerosol layers over the globe and their interaction with clouds, even above oceans and within the tropics where lidar observations are limited.

As part of ESA’s data processing chain and quality framework, the Aeolus DISC contributions cover a wide range of topics such as instrumental aspects, laser-atmosphere interactions or aircraft campaign. This also includes maintenance and improvement of the Aeolus processors for aerosol and clouds product as for wind product. Examples of the Aeolus DISC main tasks are given below :

• Algorithm refinement and instrument performance monitoring

• Quality assessment and validation of Aeolus aerosol and wind products

• Support for in-situ data campaign and synthesis of Calibration / Validation (Cal/Val) results

The Aeolus mission surpassed the scientific expectations and exceeded the planned life in orbit. The operational phase of the mission ended on 28 July 2023 after a series of last achievements : end-of-life experiments were conducted to support future lidar missions such as EarthCARE or Aeolus-2, and the first assisted re-entry into the Earth’s atmosphere was successfully monitored. Since then, the new phase of the mission focuses on providing the best quality aerosol/wind products for the atmospheric science community to support novel applications for aerosol science and strengthen the mission positive impacts on numerical weather prediction.

Contribution of TROPOS 

As part of the Aeolus DISC consortium, TROPOS provided continuous reference measurements all over the world with PollyNET ground stations for the validation of aerosol and cloud products Level-2A (L2A), and wind products Level-2B (L2B). This has contributed to the evaluation of the algorithms performance from the beginning until the end of the mission. TROPOS is taking part in the L2A aerosol optical properties product development, supporting scientific applications of the Aeolus reprocessed dataset. The activity implies preparation of the processor codes and update of technical documentation.

The main points of contact are Dr. Sebastian Bley and Ph.D candidate Dimitri Trapon. Sebastian Bley is involved in the support activities to the Cal/Val teams as scientific coordinator. He has expertise in cloud remote sensing and synergies between space-borne imagers and lidars. Dimitri Trapon is responsible of maintenance and improvement of the L2A prototype processor for aerosol/cloud optical properties products. He has expertise in the Aeolus aerosol retrieval algorithm and instrument performance monitoring.

TROPOS contributes to the success of the mission, taking advantage of the institute's experience in atmospheric particles measurement and classification using lasers operating at multiple wavelengths. The expertise of both Clouds, Aerosols and Radiation (CAR) and Lidar Applications (LA) workgroups from the Remote Sensing of Atmospheric Processes Department (RSD) are being used to assess the quality of the Aeolus products and improve their contributions to aerosol science. The Aeolus dataset are gradually disseminated to public from the ESA Aeolus Online Dissemination System at https://aeolus-ds.eo.esa.int/oads/access/. More information about the Level 2A aerosol/cloud optical properties product can be found at ESA eogateway: https://earth.esa.int/eogateway/catalog/aeolus-l2a-aerosol-cloud-optical-product.

Project info

Funding Angency: European Space Agency (ESA)

Funding number:

TROPOS AEOLUS Cost Unit R10051200
ESA contract No. 4000126336/18/I-BG
(Aeolus Data Innovation and Science Cluster (DISC) – Phase E2)
ESA subcontract No. D/553/67342749 To ESA contract No. 4000144330/24/I-AG 
(Aeolus Data Innovation and Science Cluster (DISC) – Phase F1)

Official project page

ESA Aeolus DISC 

Further links

ESA Aeolus mission

ESA introducing Aeolus

ESA Aeolus Online Dissemination System

Publications

Baars, H.,  Radenz, M.,  Floutsi, A. A.,  Engelmann, R.,  Althausen, D.,  Heese, B., Ansmann, A., Flament, T., Dabas, A., Trapon, D., Reitebuch, O., Bley, S., Wandinger, U. (2021). Californian wildfire smoke over Europe: A first example of the aerosol observing capabilities of Aeolus compared to ground-based lidar. Geophysical Research Letters, 48, e2020GL092194. https://doi.org/10.1029/2020GL092194

Flament, T., Trapon, D., Lacour, A., Dabas, A., Ehlers, F., and Huber, D.: Aeolus L2A Aerosol Optical Properties Product: Standard Correct Algorithm and Mie Correct Algorithm, Atmos. Meas. Tech., 14, 7851–7871, https://doi.org/10.5194/amt-14-7851-2021, 2021.

Trapon, D., Baars, H., Floutsi, A., Bley, S., Lacour, A., Flament, T., Dabas, A., Nehrir, A. R., Ehlers, F., and Huber, D.: Cross validations of the Aeolus aerosol products and new developments with airborne high spectral resolution lidar measurements above the Tropical Atlantic during JATAC, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-462, 2025. 

Exemplary mesurement cases

Californian wildfire smoke over Europe

In early September 2020, massive smoke plumes emitted from severe Californian wildfires were transported east across the United States. Signatures of smoke in the top troposphere have been observed by Aeolus (Fig. 2a) for more than one week during the long range transport above the Atlantic Ocean. Key optical properties such as extinction coefficient or extinction-to-backscatter ratio and their evolution in time have been measured by Aeolus. The high values reported within the L2A products derived with Standard Correct Algorithm (SCA) and Maximum Likelihood Estimation (MLE) point to dark particles and provide further evidence for biomass burning. Smoke residuals were compared to ground-based multiwavelength Raman polarization and water-vapor lidar Polly^XT above West of Europe (Fig. 2b), showing increase in backscatter light (Fig. 2c) confirming the transport above the Atlantic Ocean (Baars et al., 2021).

Stratospheric aerosols from Hunga Tonga volcanic eruption

On 15 January 2022 the Hunga-Tonga Volcano located in South Pacific Ocean emitted a huge amount of particles which penetrated the stratosphere. Due to Aeolus' flexibility, range bin setting has been adapted to measure up to 30 km altitude and one of the volcanic aerosol plumes has been observed drifting west. Signatures of stratospheric aerosols were clearly visible in Near Real Time (NRT) L2A product labelled baseline 2A13. SCA co-polar total attenuated backscatter for particles given at finer horizontal scale measurement (~ 6 km with January 2022 settings) revealed mean values of order ~2^⁻3 to ~3^⁻3 km ⁻¹ sr ⁻¹ for the fresh aerosols filament observed at ~ 25 km altitude (Fig. 3b). It has been successfully compared to the parallel signal derived from NASA CALIOP/CALIPSO satellite observations (Fig. 3c) for orbit sections with minimum geolocation offset above the Pacific Ocean (Fig. 3a). Particulate lidar ratios retrieved by the MLE algorithm on coarser horizontal scale observation of ~90km (e.g. right) reached ~50sr +/- 20sr which was valid when comparing to the literature. Latitudinal zonal mean of key optical parameters look promising to assess the global distribution of the aerosol layer when circumnavigating the Earth in Southern hemisphere.