FLEX Workshop 2023 - Summary

In September, the international FLEX workshop took place at ESA's European Space Research Institute (ESRIN) in Frascati (Italy). Over the course of three days, 110 scientists and engineers reported on the technical status of FLEX, research activities and results related to validation and fluorescence research, as well as potential areas of application such as aquatic ecosystems, agriculture, and peatlands.

The first day focused on the technical aspects of FLEX. Numerous ESA representatives and scientists from around the world reported on the status of the mission, the fluorescence signal, the validation of data products and applications in aquatic ecosystems. As reported by ESA, the launch of FLEX is scheduled for mid-2026. FLEX would then be launched into the same orbit as Sentinel-3 (S3) spacecraft at an altitude of 815 km. To achieve the required temporal coregistration with S3 OLCI and SLSTR instrument measurements, FLEX will be placed at a position 6-15 seconds ahead of S3. However, which of the three Sentinel-3 will be the tandem partner for FLEX has not yet been finalized (S3A and S3B are already in orbit and S3C launch date is yet to be defined. The satellite is mainly composed of the FLORIS instrument which is at its final assembly at Leonardo (Italy) and the satellite platform that is being developed by Thales Alenia Space (France) and assembled in TAS facilities in Belfast (UK).  The FLORIS integration will be completed in Q2-2024, followed by an instrument test and calibration campaign, prior to being shipped to TAS in the UK and mating with the satellite platform. Thereafter the whole satellite will be tested against launch and space environmental loads (mechanical and thermal) and ready for launch in 2026.

The second day started with a joint live session to a parallel fluorescence workshop in China. Speakers from both workshops reported on the potential of FLEX and fluorescence for vegetation monitoring as well as the current status of the Chinese satellite systems. The other sessions focused primarily on data products and the combination of observations with models.

The workshop concluded on the third day with a focus on potential applications for the carbon and water cycle and ecosystem research. Among other things, the measurement of fluorescence to determine vegetation properties in forest ecosystems and agriculture as well as applications in the field of aquatic ecosystems and peatlands were presented.

Results

One of the most important results of the workshop was that there should be a stronger focus on research into applications for aquatic ecosystems. More data needs to be collected over coastal regions and a strategy for the calibration of FLEX measurements over water surfaces needs to be developed. In addition, ESA has simulated test datasets that should be further expanded to represent different "real world" scenarios and test machine learning algorithms. This data is to be made available by ESA in the future. At the same time, existing datasets on the FLEX campaigns should also be made accessible and made available in repositories. One example is data from aircraft campaigns with the Hyplant sensor from Forschungszentrum Jülich. It was also noted that instruments for in-situ measurements should be characterized, and protocols and uncertainties published, as the quality of those measurements is not always clear. Furthermore, the industry is encouraged to develop low-cost instruments for SIF measurements such as low-cost spectrometers and Unmanned Aerial Vehicle (UAV)-based measurement systems. Finally, the discussion started on how fluorescence data can be used holistically. The community is encouraged to explore and compare methods for data assimilation and data fusion.

Posters and presentations

The workshop was accompanied by a poster session with 37 posters from scientists, institutions, and companies.

The posters and presentations can be viewed via the workshop website:  to the workshop website

Publications and datasets

Many scientific studies and datasets were mentioned during the workshop. You can find a selection here: