FLEX Fluorescence Workshop 2026 - Posters Wall by Sabrina Lodadio

Instructions:

sabrinalodadio — 2026-02-27 15:42:55 UTC

- Title: poster title + author name and abstract ID

- Body text: short abstract or 2–3 sentence summary, plus contact email (optional).

- Attachment: upload the poster as a PDF or image (JPG/PNG); Padlet supports both.

ID:141 AndesFlux: First SIF ground-based observations in the western amazon flux network. Cosio et al.

ecosio7 — 2026-02-28 13:06:16 UTC

This report concerns the AmeriFlux Tambopata site (PE-TNR), in southeastern Peru. The tower registers water and carbon fluxes since 2017 in this Amazonian primary forest. Since March 2025, a FloX field spectrometer (JB Hyperspectral Devices GmbH) has been operating on the site. Unlike published reports based on satellite SIF observations of the Amazon, we observe that seasonal SIF yield at the site is primarily driven by water availability.

Assessing Plant Adaptive Strategies and Stress Tolerance via Chlorophyll Fluorescence and Photoprotective Pigment Dynamics. Montoro et al. ID142

2026-03-01 12:28:05 UTC

The work was carried out within the framework of the “Implementation of the Spanish Calibration and Validation Plan for the FLEX-S3 Mission (SpaFLEXImp)”, in Doñana (Spain) in 2025. The objective was to assess whether hyperspectral measurements could detect species adaptation to different habitats. The results demonstrate the capability of hyperspectral signatures to detect the differential adaptation of each shrub species to contrasting environments through the regulation of fluorescence and pigments.

email: amelia.montoro@csic.es

Evaluating the strength of the physiological contribution to the red and far-red SIF signal over seven sites in Europe

2026-03-01 15:49:26 UTC

Leveraging Solar-Induced Fluorescence for Mechanistic Understanding of Water and Carbon Fluxes. Yunfei Wang et al. ID201

2026-03-01 18:50:15 UTC

We introduce STEMMUS-MLR, a SIF-based ecohydrological model that integrates soil moisture dynamics to jointly estimate GPP and ET. Across diverse ecosystems, it matches eddy-covariance observations and outperforms empirical SIF approaches, reducing uncertainty in carbon–water flux estimates from site to regional scales.

email: y.wang-3@utwente.nl

Towards FLEX for inland waters: analysis of ground, airborne and spaceborne data in Lake Garda. Panizza et al. ID: 126

2026-03-01 21:17:54 UTC

This study, conducted within the FLEX-ITA project, evaluates the potential of SIF for monitoring phytoplankton dynamics in aquatic environments in support of the FLEX mission. This study focuses on dataset quality control and signal-to-noise ratio assessment of airborne sensors as a prerequisite for reliable water quality products, such as Chlorophyll-a (Chl-a) and SIF maps. Results showed robust performance (~10% mean deviation from in situ data) and demonstrated that SIF can provide complementary information on phytoplankton physiology and trophic status.

panizza.l@irea.cnr.it

Diurnal variation in solar-induced chlorophyll fluorescence and CO2 uptake of a Malaysian natural tropical forest: a tower-based study. Morozumi et al. ID 153

2026-03-01 22:17:09 UTC

Summary:

•Diurnal variations of SIF and environmental factors were analyzed in a tropical evergreen forest (AsiaFlux PSO site), including intra-canopy SIF.

•We found that understory fluorescence plays a key role in afternoon SIF patterns, influenced by VPD and light conditions.

•Leaf-level data support findings of diurnal SIF patterns.

e-mail: morozumi.tomoki@nies.go.jp

The MicroCarb Satellite Mission: Overview and Development of the SIF Retrieval

2026-03-01 22:19:17 UTC

MicroCarb is a UK-French bilateral satellite mission designed to map the sources and sinks of atmospheric CO₂, but will yield a Level 2 solar-induced chlorophyll fluorescence (SIF) product. Launched in July 2026, the mission is currently in its calibration and validation phase.

We present an overview of the MicroCarb mission and describe the SIF retrieval algorithm and its processing workflow. We also present results from orbit simulation experiments, demonstrating the potential to deliver robust global SIF estimates from space across a range of scenarios, with suitable auxiliary retrieval characteristics.

contact: mpc24@le.ac.uk

Evaluation of remote sensing methods for non-photochemical quenching (NPQ) estimation. Jiang et al. ID: 143

hjiang31 — 2026-03-01 22:43:02 UTC

This study compared three types approaches for estimating non-photochemical quenching (NPQ) from canopy reflectance data in a maize field experiment, including model inversion, vegetation indices, and spectral fitting method. The results showed that model inversion performed poorly, while PRI-related indices had more stable and accurate NPQ estimation across temporal scales. These findings support the development of satellite-based products for ESA’s FLEX mission. email: h.jiang@utwente.nl

Intercomparison experiment of Field spectroradiometers for FLEX L2 product Validation. Jimmy A. Muela et al. ID 155

jimmuela — 2026-03-02 07:57:55 UTC

This work presents and outdoor intercomparison of Field spectroradiometers within the framework of the SpaFLEX project. The main objective of this study is to perform an outdoor intercomparison of field spectroradiometers using radiative transfer simulations with LibRadtran as a physical reference. This approach allows us to account for both climatological and technical challenges affecting field measurements and to enable the future development of a robust intercomparison protocol. Such a protocol would be essential for ensuring the consistency and reliability of field measurements, becoming a solid reference for future FLEX S-3 Level-2 Calibration and Validation activities. email: jmuepil@inta.es

SIFcam Dual Camera System for Sensing Solar-induced Fluorescence – Data Processing and Uncertainty Assessment. Pla Guerrero et al. ID 167

2026-03-02 08:28:04 UTC

SIFcam is a lightweight dual-camera UAV system for mapping solar-induced chlorophyll fluorescence (SIF) at 760 nm while capturing vegetation structure at centimeter resolution.

An updated workflow targets robust orthomosaics, comparing a post-mosaicking alignment and blending approach (WF1) with a pre-alignment, quality-selected single-pixel mosaicking approach (WF2). An uncertainty tree diagram is presented for the SIFcam and its accuracy is evaluated via DART simulations assessing effects of canopy structure and viewing/illumination geometry. A winter wheat experiment further demonstrated added value for phenotyping when combined with UAV multispectral indices. Contact:

d.pla-guerrero@fz-juelich.de

How can we benefit from TROPOSIF observations in terrestrial biosphere model development? Thum et al.

2026-03-02 08:30:50 UTC

In this work we assess the usefulness of TROPOSIF data in combination of terrestrial biosphere model QUINCY. Presented by Gregory Duveiller and Tristan Quaife in the venue. Contact: tea.thum@fmi.fi.

Advancing SIF Retrieval for FLEX: Integrating UAV Hyperspectral, FluorSpec and Radiative Transfer Modelling in Potato and Maize Systems – Camino et al. ID-108

2026-03-02 08:44:14 UTC

We validate UAV-derived SIF retrievals across nitrogen gradients in maize and potato using FLD and FluorSpec measurements. Integrating SIF within an RTM-constrained hybrid inversion framework improves retrieval of photosynthesis-related traits and supports FLEX L2B/L2C calibration and validation.

email: carlos.caminogonzalez@wur.nl

Comparative Assessment of Methods for Quantifying the Escape Probability of Red and Far-red SIF from the Leaf to the Canopy Scale (ID 147)

2026-03-02 08:57:07 UTC

Remote sensing of solar-induced chlorophyll fluorescence (SIF) provides direct insights into photosynthetic activity, but its physiological interpretation is complicated by factors such as absorbed radiation, non-photochemical quenching, canopy and atmospheric scattering, reabsorption, and sensor effects. A key challenge is accurately estimating the canopy escape probability of SIF (σF), particularly given wavelength-dependent differences between red (687 nm) and far-red (760 nm) fluorescence. Using airborne HyPlant data from the 2019 ESA FLEXSense campaign in Germany, this study compared multiple reflectance-based methods for estimating σF against a SCOPE model–based reference combined with Gaussian process regression. Results show that the far-red escape probability (σF760) can be reliably estimated, especially with the NIRvH2 and saR2F methods, whereas the red escape probability (σF687) remains uncertain, highlighting important implications for validating the upcoming FLEX satellite product.

Integrating solar-induced chlorophyll fluorescence (SIF), land surface temperature (LST) and vegetation indices for machine learning-based drought stress detection in a forest. McKeever et al. (ID 170).

2026-03-02 09:50:46 UTC

This study explores the integration of SIF, LST and hyperspectral vegetation indices from airborne HyPlant data to detect physiological drought stress at an irrigation-manipulation site in the Scots pine forest of Pfynwald, Switzerland. Using these remote sensing features together with in-situ measurements of soil water potential, leaf-level gas exchange and sap flow, we train machine learning models that identify drought-stress patterns consistent with seasonal drought patterns and the treatment layout. Contact: s.mckeever@fz-juelich.de.

On the use of the FLoX spectrometer for validating FLEX data over water. Bresciani et al. ID: 125

2026-03-02 10:21:14 UTC

This study, conducted within the PHY2FLEX project, investigates the use of SIF to assess phytoplankton physiology, estimate Chlorophyll-a, and support satellite calibration and validation. With two field campaigns conducted in October 2025 in Venice Lagoon and Lake Garda, with synchronized EnMAP acquisitions, allowed to collect radiometric and water quality data using the FloX spectrometer and other instruments. Results showed that FloX reliably captured fluorescence signals consistent with other sensors and EnMAP data, confirming its suitability for aquatic fluorescence retrieval.

bresciani.m@irea.cnr.it

A multi-scale spatial sampling strategy for FLEX product validation within the SpaFLEX project. Gómez-Giráldez et al. ID:158

2026-03-02 10:49:38 UTC

A multi-scale spatial sampling strategy is developed for FLEX-S3 product validation across heterogeneous Mediterranean ecosystems.
Optimal elementary sampling unit (ESU) allocation integrates finite population correction and Neyman optimal allocation.
Within-ESU variability is quantified at 4 cm resolution using hyperspectral imagery, with PRI and ChIRE as independent proxies for reflectance and fluorescence.
A hierarchical upscaling chain with uncertainty propagation bridges point measurements to the 300 × 300 m FLEX pixel scale, meeting mission accuracy requirements.

Error Budget Tool: A Diagnostic Framework for SIF Retrieval Algorithm. Chierichetti et al. ID 189

pietrochierichetti — 2026-03-02 13:55:54 UTC

Error Budget Tool (EBT) is a diagnostic framework developed to quantify the impact of instrumental error sources on SIF retrieval within the FLEX Level-2 processing chain. The tool enables fast and controlled simulations, ranging from ideal noise-free to realistic instrument configurations. A simplified instrumental noise model is implemented to assess the effects of ARG, RSRA, RXRA, and photon noise on key SIF products, including O₂-A, O₂-B, red and far-red peaks, and spectrally integrated SIF. Results from synthetic TDS scenes show that photon noise is the dominant contributor to retrieval dispersion, while ARG introduces systematic bias. Noise-free simulations demonstrate excellent agreement between refrence and retrieved SIF, confirming that the L2B algorithm is fully compliant under ideal conditions. Overall, the EBT provides an effective and lightweight framework to identify dominant error sources and support targeted refinements of the FLEX Level-2 SIF processor.

email: pietro.chierichetti@unimib.it

DART-based canopy-to-photosystem downscaling of deciduous forest airborne far-red solar-induced fluorescence. Regaieg et al. ID 183

2026-03-02 15:28:17 UTC

This work presents a top-of-canopy level to photosystem level SIF downscaling method based on the 3D radiative transfer model DART and applied on HyPlant SIF acquisitions over a deciduous beech forest stand. The method relies on accurately simulating the forest stand in DART using retrieved canopy traits from HyPlant hyperspectral acquisition and a Convolutional Neural Network trained on synthetic training data generated in DART. Then, these retrievals are used to forward simulate the top-of-canopy SIF in DART and estimating the photosystem-level Fluorescence Quantum Efficiency per pixel.

email: oregaieg@uni-bonn.de

Multi-scale LAI and fAPAR estimations for biotic stress attribution (FLEX cal/val). Preidl et al. ID193

2026-03-02 15:45:38 UTC

This work proposes a calibration and validation (cal/val) approach for the FLEX mission, as part of the FLEXvalGER consortium, focusing on multi-scale estimation of LAI and fAPAR to improve attribution of biotic forest stress. An integrated DHP and PAR sensor network, combined with UAV and satellite upscaling, is designed to validate L2C products, quantify uncertainties, and distinguish structural canopy effects from physiological stress reflected in SIF. Contact: sebastian.preidl@julius-kuehn.de

SIFcam - Advancing a Research Prototype Towards a Scalable Platform with potential for FLEX validation

2026-03-02 16:27:07 UTC

Floronics, a research-driven start-up, is advancing SIFcam from a validated research prototype towards a scalable, flexible platform over the next two years. Planned developments include further hardware miniaturization, improved functionality such as geotagging and WiFi interface, stable radiometric performance, and a consolidated processing chain for automated SIF mapping. These efforts aim to provide standardized, robust, high-resolution SIF data sets that support FLEX calibration and validation activities, process-based model development, and applications in plant phenotyping and precision agriculture.

e-mail: l.kremer@fz-juelich.de

tristanharmel — 2026-03-02 17:33:44 UTC

Simultaneous retrieval of water quality and fluorescence properties from FLEX-Sentinel-3 synergy. Mukherjee, S. and Harmel, T.

ID 144

Comparative analysis of full-spectrum SIF Principal Component Reconstruction versus SpecFit. Morata et al. ID175

2026-03-02 18:22:07 UTC

This study uses PCA reconstruction approach to retrieve the full solar-induced fluorescence (SIF) emission spectrum (640–850 nm) from measurements in the O₂ absorption bands. Using simulated and field datasets, PCrec is evaluated against SpecFit at canopy level and leaf-clip measurements at leaf level, comparing with other retrieval methods, demonstrating comparable or improved accuracy while reducing computational cost by an order of magnitude. The results highlight the potential of PCA-based reconstruction for efficient full-spectrum SIF estimation and its suitability for upcoming fluorescence missions and airborne products. miguel.morata@uv.es

Assessing the impact of an explicit representation of the nitrogen cycle on SIF and GPP dynamics simulated by a Land Surface Model across European sites. Tuffery et al. ID: 178

2026-03-02 18:24:29 UTC

We recently implemented the ORCHIDEE fluorescence module in a new model version that explicitly represents the nitrogen cycle. Here, we compare and evaluate prior simulations of APAR, GPP, and SIF from two versions of the ORCHIDEE model (with and without the nitrogen cycle) at two sites, Mieming (FAIR) and Leinefelde, using data from the AustroSIF database. This study is the first step toward a joint assimilation of both GPP and SIF.

email : leo.tuffery@lsce.ipsl.fr

Measuring nighttime altitude-dependent O2A absorption bands deepening over an illuminated greenhouse. Genesio et al. ID133

2026-03-02 19:03:45 UTC

Here we show an experiment aiming at testing the capabilities of night-time acquisition from PRISMA satellite to identify fluorescence emission from an illuminated greenhouse. Simultaneous airborne fluorescence acquisitions at different altitudes enabled to measure the altitude-dependent atmospheric transmittance in the O2A and O2B bands.

FLEX Mission Support in Heterogeneous Ecosystems: Integrated Proximal Sensing and Ground-Based Monitoring at Majadas de Tiétar. Alonso et al. ID 186

2026-03-02 19:06:06 UTC

The Majadas de Tiétar station (ICOS/FLUXNET ES-LMa) is a long-term observatory in an open Quercus ilex dehesa forest, combining eddy covariance, meteorological, soil and tree-scale measurements to quantify and partition carbon, water and energy fluxes between tree and grass layers. It is being upgraded with proximal remote sensing (FLOX, SWIR, thermal and multispectral cameras) to monitor chlorophyll fluorescence, canopy water content and surface temperature, support TSEB/3SEB modelling, and contribute to ESA FLEX calibration/validation and upscaling activities within SPAFLEX. Contact: alonso@ceam.es

Towards a FLEX sensor fusion system for monitoring gradual global land cover change. Masiliūnas, ID 173

2026-03-02 21:08:44 UTC

I propose a new framework to fuse FLEX data with Sentinel-3 and Sentinel-2 to achieve on-demand global land cover monitoring with high spectral, temporal and spatial resolution, and include gradual change via land cover fractions. The framework, called Land Cover Analysis and Research System (LCARS), will aim to be computationally light and interpretable by making use of existing products as much as possible, fully open and on-demand, reusing existing land cover mapping software and built on openEO. Please reach out if you would like to collaborate: dainius.masiliunas@wur.nl

Validation strategy of FLEX surface reflectance and irradiance using autonomous ground reference data. Zimmermann et al.

2026-03-03 08:10:42 UTC

The FLEX bottom of atmosphere products surface apparent reflectance and at-surface solar irradiance will be validated using autonomous ground reference data supplied by the LANDHYPERNET and INSIF networks. The validation itself is based on a comparison metric, where the difference between the FLEX products and the reference datasets should be smaller than the combined extended uncertainty of both. When computing the difference between satellite and ground reference data, it is important that the measurands are as similar as possible, i.e. they must be harmonised spatially, spectrally, angularly and temporally.

LANDHYPERNET is an automated network of hyperspectral radiometers, providing multi-angular reflectance measurements for satellite validation. The instrument consists of 2 sensors, covering VNIR to SWIR range. The VNIR data is collected at a wavelength range of 380 – 1000 nm with 0.5 nm sampling and 3 nm resolution, while the SWIR sensor measures in between 1000 – 1680 nm with 3 nm sampling and 10 nm resolution. Reflectance measurements are taken with a field of view (FOV) of 5° and irradiance measurements with a 180° FOV.

INSIF (International Network of Sun Induced Chlorophyll fluorescence) is a network providing processed FLOX (fluorescence box) measurements. It provides measurements from 650 – 800 nm with a 0.17 nm sampling and 0.3 nm resolution and from 400 – 950 nm with 0.65 nm sampling and 1.5 nm resolution. FLOX has a dual FOV allowing it to measure upwelling radiance (FOV: 25°) and downwelling irradiance (FOV: 180°) simultaneously.

The harmonisation approach will require the following steps (fully for reflectance, partially for irradiance): In the spectral harmonisation the dataset with the finer resolution will be convolved to the one with the coarser resolution, i.e. FLEX to HYPERNETS or FLOX to FLEX. For spatial harmonisation, Sentinel-2 data will be analysed to find the least variable, hence best suited region of interest (ROI) and quantify the spatial variability. The angular and temporal correction will be done using a BRDF model and linear interpolation. Each of those steps will introduce additional uncertainties, which will propagated together with the input uncertainties of FLEX, FLOX and HYPERNETS.

In this contribution, we will present the strategy and tools under development to validate the afore mentioned bottom of atmosphere FLEX products starting from ground data using FLEX simulated data.

email: astrid.zimmermann@npl.co.uk

Towards an emulation-based SIF retrieval method for FLEX data. Buffat et al. ID15

2026-03-03 09:56:52 UTC

The FLuorescence EXplorer (FLEX) mission will deliver the first global Sun-Induced Fluorescence (SIF) product at 300 m spatial resolution enabling field-scale analysis. However, its low temporal sampling rate limits its utility for time-critical applications. To bridge this gap, we propose the use of a sensor-agnostic SIF retrieval method to combine the FLEX SIF product with estimates from other spaceborne hyperspectral sensors.

ID: 144 Simultaneous retrieval of water quality and fluorescence properties from FLEX-Sentinel-3 synergy

2026-03-03 10:14:14 UTC

This study, conducted within the PHY2FLEX project, presents an optical remote-sensing framework to evaluate the synergistic Sentinel-3 OLCI and FLEX-FLORIS product for retrieving water quality indicators, including chlorophyll concentration and physiological proxies such as fluorescence quantum yield. The approach exploits blue-green spectral information from S3-OLCI alongside high-resolution red-NIR measurements from FLEX-FLORIS to resolve Sun-Induced Fluorescence (SIF). A radiative-transfer-based inverse model is developed to jointly estimate optically active water constituents, SIF quantum yield and fluorescence attenuation. The framework is evaluated using simulated and in situ/satellite datasets convolved to 0.5 nm, 3 nm, and the S3+FLEX fused spectral configurations. Validation against synthetic and field data demonstrates comparable or improved performance in chlorophyll and quantum yield retrieval relative to ultra-fine (0.5 nm) spectral resolution. Overall, the study attempts to contribute in advancement of real-time retrieval of bio-optical parameters through Sentinel+FLEX synergy.

email: soham.mukherjee@magellium.fr

Downscaling Solar-Induced Fluorescence in Complex Forest Canopies using 3D Radiative Transfer Modelling. ID 164

sajasalattna1993 — 2026-03-03 11:01:11 UTC

This study employs a physically based approach combining airborne imaging spectroscopy, 3D Discrete Anisotropic Radiative Transfer (DART) modelling, and machine learning to scale HyPlant canopy-level SIF radiance of deciduous, coniferous, and mixed forest stands down to leaf and photosystem levels. The downscaled SIF signal, indicating forest photosynthetic activity, can act as an early warning signal of abiotic/biotic stress impacts and support adaptive forest management under global warming conditions

email: s.salattna@fz-juelich.de

ID 174: SIFFI: Bayesian solar-induced fluorescence algorithm for remote sensing of vegetation

2026-03-03 12:59:58 UTC

- We present a novel SIF retrieval algorithm, SIFFI, designed to jointly retrieve the full SIF emission spectrum and surface reflectance without imposing parametric constraints on the spectral shape of the retrieved signal.

- SIFFI is applicable at both top-of-canopy (TOC) and TOA levels, enabling its use across a wide range of measurement platforms, from ground-based instruments to different satellite sensors.

- At TOC level, SIFFI is successfully applied to measured data from a Fluorescence Box (FloX) instrument. At TOA-level, SIFFI is able to provide accurate retrievals using simulated

datasets both under perfect atmospheric correction and when the atmospheric state is inaccurately characterized during the retrieval process with the latter achieved by utilizing the Approximation Error (AE) method.

Chlorophyll Fluorescence Measurements Across Scales at the Sodankylä ESA-FMI SUPERSITE, Honkanen et al. ID: 121.

2026-03-03 13:02:29 UTC

This poster presents multi-scale chlorophyll fluorescence measurements conducted in Sodankylä. Observations include airborne measurements (Piccolo), tower and canopy measurements (Flox and Piccolo), bog measurements (Flox), and active needle-level measurements (Monipam). Contact: marika.honkanen@fmi.fi

Use of Chlorophyll Fluorescence for Early Detection of Viral Infection in Sweet Potato Plants. ID: 161

2026-03-03 14:31:56 UTC

Interpreting vegetation spectral signals under biotic stress remains challenging. Viral infections often disrupt photosynthesis, reducing photochemical efficiency (ΦPSII)

and altering nonphotochemical and fluorescence quenching dynamics. However, these early physiological changes may be missed by broadband structural indices. Highresolution

measurements of pigment absorption and chlorophyll fluorescence provide key insights into energy partitioning. This study evaluates if these metrics—and their

derivatives—can improve early detection of viral infections in field-grown Ipomoea batatas. Email: julio.marchante@uv.es

Understanding Non-linear Chlorophyll Fluorescence Dynamics for Water Stress Detection. ID: 140

2026-03-03 14:36:03 UTC

This study explores how the nonlinear

dynamics between chlorophyll

fluorescence and photosynthetic

efficiency shift under distinct

environmental stress scenarios. Across

three experimental designs, we

characterize dynamic responses under

varying light and abiotic stress

conditions, with drought serving as a

baseline, to enhance the physiological

interpretation of FLEX-derived SIF

observations. Email: cynthia.chardi@uv.es

FLORES: Mechanistically tracking forest photosynthesis and transpiration through multiscale chlorophyll fluorescence signals

2026-03-03 14:52:08 UTC

The FLORES project will develop an innovative mechanistic approach (MLR-USO) for tracking gross primary production and transpiration of European forests. A groundbreaking aspect of FLORES is its multi-scale approach that deploys unmanned aerial vehicle (UAV)-mounted SIF sensor (AirFloX) over forests, effectively bridging the critical observational gap between fine leaf-level processes and broader scale observations from satellite platforms. A fleet of UAV (LiDAR, thermal, multispectral), GNSS-T antennas on the ground, and field-based spectrometer (FloX) will complement leaf-level measurements of model parameters, enabling model application at the canopy and stand scales. Eddy covariance will serve as validation datasets before applying the model at large scales with TROPOMI and later FLEX. Contact: q.beauclaire@uliege.be

High-spatial-resolution gross primary production estimation from Sentinel-2: A baseline for future SIF integration. De Clerck et al. ID110

2026-03-03 15:47:05 UTC

Highlights:

• Hybrid vs. data driven models for high spatial resolution (20m) Gross Primary

Productivity from Sentinel-2 reflectance

• Optimizing Gaussian processes regression models with Active Learning for 10 Plant Functional Types

• Incorporation of meteorological, soil and DEM variables

• Validation against eddy covariance flux towers in Europe and US

• Scalable workflow in Google Earth Engine / openEO for accessible and reproducible carbon monitoring

email: emma.clerck@uv.es

Airborne system design and data acquisition campaigns for the SpaFLEX project within the Spanish Cal/Val plan of ESA’s FLEX mission. Muñoz et al. ID172

2026-03-04 10:42:28 UTC

The calibration and validation of FLEX require the use of airborne systems capable of providing estimates of the SIF observable. One such system is INTA's

Hadwall Chlorophyll Fluorescence Imager.

The overall objective of the SpaFLEX project is to develop a Spanish Cal/Val plan for FLEX products. This plan includes the selection of representative test sites, measurement protocols, and uncertainty calculations for Level 2 products. Airborne campaigns provide essential medium scale data over large areas with high efficiency, enabling the improvement of algorithms and models that estimate the propagation of fluorescence and reflectance. This work describes the integration of an airborne system and the campaign carried out in October 2025.

Contact: munozsf@inta.es

SpaFLEX Procedure for Propagating in-situ Sun-induced Chlorophyll Fluorescence and Reflectance Uncertainty in Cal/Val FLEX L2 Products. Peón et al. ID 150

2026-03-04 10:57:03 UTC

SpaFLEX project is implementing a comprehensive Calibration and Validation (Cal/Val) plan for the FLEX-S3 mission

The uncertainty propagation of in-situ fluorescence (SIF) and surface reflectance (Ref) for the 300x300 m area representing a FLEX pixel is performed using the Law of Propagation of Uncertainties and Monte Carlo methods, in successives steps using CoMet-Punpy tool (Community Metrology Toolkit - Propagation of UNcertainties in Python)

This work presents the uncertainty estimation of in-situ SIF and Ref measurements for two Cal/Val plots in the recent Cal/Val campaign carried out in July 2025 in SpaFLEX Cal/Val test site of Doñana (Huelva, Spain)

FLEX radiometry monitoring using VICALOPS service. Berthelot B. et al. ID135

2026-03-04 16:24:17 UTC

VICALOPS is the European Space Agency's (ESA) new service dedicated to monitoring the radiometric performance of satellite sensors. It integrates various vicarious calibration methods that leverage reflectance from bright desert surfaces, snow, deep convective clouds (DCC), atmospheric molecules, and sunglint. The system synthesizes results by combining data from these methods to provide a comprehensive overview of sensor calibration and stability.

The VICALOPS service has been set up to monitor the radiometric performance of the FLEX FLORIS sensor using stable desert sites and deep convective clouds. Seven spectral windows, selected to avoid strong gaseous absorption features, are used to ensure robust and consistent radiometric assessments. Time series derived from these windows enable the detection of radiometric drifts and support the long-term monitoring of sensor stability throughout the mission lifetime.

email: beatrice.berthelot@magellium.fr