Aeolus Calibration and Validation (Cal/Val) activities are performed to quantify the mission's system response (calibration) to known signal inputs and to verify the performance by comparison with independent sources of data (validation).
The Atmospheric Laser Doppler Instrument (ALADIN), onboard the Aeolus mission, is a Direct Detection Doppler Wind Lidar operating in the ultra-violet spectral region (355 nm).
The lidar is aimed 35° from nadir and 90° to the satellite track (on the side away from the Sun), in order to transmit and receive light perpendicular to the speed of the satellite. This allows ALADIN to determine the east-west horizontal component of the wind along most of its orbit around the Earth.
The receiver analyses the Doppler shift of the backscattered signal with respect to the frequency of the transmitted laser pulse and as a function of time. In this way, it is possible to determine the wind at various altitudes above the surface.
Two optical receivers measure the frequency of the light backscattered along the instrument line of sight by molecules (‘Rayleigh signal’), and particles, ice crystals and water droplets (‘Mie signal’). This is then compared with the frequency of the emitted light pulses.
The following Aeolus products are available to all users:
- Level 1B: Preliminary HLOS (Horizontal Line of Sight) wind observations and useful signals for Rayleigh and Mie receivers. Standard atmospheric correction, receiver response and initial bias corrections applied.
- Level 2B: Scientific wind product for users. Geo-located consolidated HLOS wind observation with actual atmospheric correction and further bias corrections applied.
- Level 2C: Aeolus assisted wind fields resulting from NWP (Numerical Weather Prediction) assimilation processing. Data co-located time and space with Aeolus wind observations.
Access to the Aeolus aerosol/cloud product is limited to dedicated expert groups until its public release:
- Level 2A: Scientific aerosol/cloud profile product. Geo-located consolidated backscatter and extinction profiles, backscatter-to-extinction ratio per observation, scene classification. Furthermore, attenuated backscatter on measurement level.
Read more about Aeolus products:
- Aeolus Sensor and Product Description
- Aeolus L1B Algorithm Theoretical Baseline Document
- Aeolus L1B Input/Output Data Definitions Interface Control Document
- Aeolus L2B Algorithm Theoretical Baseline Document
- Aeolus L2B/2C Processor Input/Output Data Definitions Interface Control Document
- Additional documents about Aeolus Calibration and Validation products on the Aeolus Cal/Val AO page
Major processor releases are scheduled twice per year. The current Aeolus Near Real Time (NRT) data products are available in the latest processor baseline B11. The main product quality improvements to the previous processor are described in this technical note.
Additionally, a fully homogeneous dataset of L1B and L2B products is available in baseline 10, which covers the time period from 20 April to 8 October 2020 as well as the reprocessed dataset from 28 June until 31 December 2019.
A number of tools are available for visualising, processing and analysing Aeolus data.
Data visualisation tools
VirES for Aeolus
VirES for Aeolus is a highly interactive data manipulation and retrieval interface for ESA's Aeolus mission products. It includes tools for studying various atmospheric parameters, in space and time, measured by the Aeolus satellite.
CODA and HARP
The ESA Common Data Access (CODA) and HARP tools have been developed for reading atmospheric data from the ESA Envisat satellite, and have been extended to read Aeolus data in the common Earth Explorer File Format.
Satellite and orbit visualisation tools
ESOV - the Earth Observation Swath and Orbit Visualisation tool - provides the means to visualise the instrument swaths of all ESA Earth Observation Satellites and assist in understanding where and when satellite measurements are made and ground contact is possible.
EVDC Orbit Prediction Tool
The EVDC Orbit Prediction Tool generates and visualises satellite's overpasses, including Aeolus. Temporal overpasses can be calculated for any time period - either past or future - for any location.
SAMI (Satellite Mission Editor & Player) is a freely available software application for visualisation of high-resolution 3D and 2D scenarios of ESA Earth Observation satellites.
Command line executables
The Earth Observation CFI Software is a collection of precompiled C libraries for timing, coordinate conversions, orbit propagation, satellite pointing calculations, and target visibility calculations.
The ESA framework for Aeolus data quality assurance is the Aeolus DISC (Data, Innovation and Science Cluster), including processor evolution, quality monitoring and a central role in calibration, validation and NWP impact assessment. It consists of expert centres and teams located in Germany, UK, France, Italy and the Netherlands and is led by the German Aerospace Center (DLR).
Aeolus Quality Control Reports on L1B/Instrument, L2A and L2B products are currently available to Aeolus Cal/Val teams and will become publicly available after public data release.
Announcement of opportunity
An announcement of opportunity is open for calibration and validation (cal/val) teams to apply for Aeolus data. The aim of the call is to invite new groups to participate in Aeolus cal/val activities, and as such the teams will have early access to Aeolus data products before their public release.