Nadine Gobron

Nadine Gobron
European Commission | ec · Joint Research Centre (JRC)

PhD

About

274
Publications
64,076
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16,484
Citations
Additional affiliations
September 1994 - May 1997
University of Clermont Auvergne
Position
  • PhD
October 2002 - present
European Commission
Position
  • Project Manager

Publications

Publications (274)
Article
Full-text available
The fraction of absorbed photosynthetically active radiation (FAPAR) is one of the bio-geophysical Essential Climate Variables assessed through remote sensing observations and distributed globally by space and environmental agencies. Any reliable remote sensing product should be benchmarked against a reference, which is normally determined by means...
Article
Full-text available
Satellite products provide the best way to monitor the solar radiation reaching the Earth's surface on a global scale. However, their capability to monitor solar radiation trends needs to be constantly evaluated. This depends on their temporal stability and the accurate representation of all processes driving solar radiation. This study evaluates t...
Conference Paper
Full-text available
The fraction of photosynthetically active radiation (FAPAR) plays a crucial role in vegetation carbon capture and dynamic vegetation models, requiring accurate and long-term observations for understanding carbon dynamics. Despite advancements in satellite-derived FAPAR products, validating their accuracy remains critical. Current in-situ validation...
Article
Full-text available
Satellite and in situ sensors do not observe exactly the same measurand. This introduces a mismatch between both types of measurements in the spatial or temporal. The mismatch differences can be the dominant component in their comparison, so they have to be removed for an adequate validation of satellite products. With this aim, we propose a method...
Conference Paper
Full-text available
GBOV (Copernicus Ground-Based Observation for Validation), is an element of CLMS (Copernicus Land Monitoring Service). Its initial purpose was to support yearly validation effort of core CLMS product (TOC-R, Albedo, LAI, FAPAR, FCOVER, SSM and LST), five of whom are listed among GCOS Essential Climate Variables (ECV). GBOV has however reached a muc...
Article
Full-text available
Gridded bottom-up inventories of CO2 emissions are needed in global CO2 inversion schemes as priors to initialize transport models and as a complement to top-down estimates to identify the anthropogenic sources. Global inversions require gridded datasets almost in near-real time that are spatially and methodologically consistent at a global scale....
Article
The Global Ecosystem Dynamics Investigation (GEDI) aims to provide improved characterization of forest structure, and plant area index (PAI) is one of many variables provided in the official GEDI Level 2B (L2B) product suite. However, since release, few quantitative validation studies have been conducted. To reach Stage 1 of the validation hierarch...
Article
Full-text available
1. Digital hemispherical photography (DHP) is widely used to derive forest biophysi-cal variables including leaf, plant, and green area index (LAI, PAI and GAI), the fraction of intercepted photosynthetically active radiation (FIPAR), and the fraction of vegetation cover (FCOVER). However, the majority of software packages for processing DHP data a...
Preprint
Full-text available
Gridded bottom-up inventories of CO2 emissions are needed in global CO2 inversion schemes as priors to initialize transport models, and as a complement to top-down estimates to identify the anthropogenic sources. Global inversions require gridded datasets almost in near-real time that are spatially and methodologically consistent at a global scale....
Article
Full-text available
Monitoring snow cover to infer climate change impacts is now feasible using Earth observation data together with reanalysis products derived from Earth system models and data assimilation. Temporal stability becomes essential when these products are used to monitor snow cover changes over time. While the temporal stability of satellite products can...
Article
Full-text available
Accurate monitoring of albedo trends over snow is essential to evaluate the consequences of the global snow cover retreat on Earth’s energy budget. Satellite observations provide the best way to monitor these trends globally, but their uncertainty increases over snow. Besides, different products sometimes show diverging trends. A better assessment...
Article
Full-text available
Multiple satellite products are available to monitor the spatiotemporal dynamics of surface albedo. They are extensively assessed over snow-free surfaces but less over snow. However, snow albedo is critical for climate monitoring applications, so a better understating of the accuracy of these products over snow is needed. This work analyzes long-te...
Article
Full-text available
This article presents the evaluation of the Copernicus Sentinel-3 Ocean Land Colour Instrument (OLCI) operational terrestrial products corresponding to the green instantaneous Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) and its associated rectified channels. These products are estimated using OLCI spectral measurements acquired...
Article
Full-text available
More than half of the solar energy absorbed by land surfaces is currently used to evaporate water 1. Climate change is expected to intensify the hydrological cycle 2 and to alter evapotranspiration, with implications for ecosystem services and feedback to regional and global climate. Evapotranspiration changes may already be under way, but direct o...
Preprint
Full-text available
Monitoring snow cover extent is now feasible using Earth Observation (EO) data together with reanalysis products (derived from earth system model and data assimilation) to infer climate change impacts. Temporal stability is essential but can be altered by the combination of multiple satellite sensors and their degradation, or by the assimilation of...
Article
A framework is proposed for assessing the physical consistency between two terrestrial Essential Climate Variables (ECVs) products retrieved from Earth Observation at global scale. The methodology assessed the level of agreement between the temporal variations of Leaf Area Index (LAI) and Fraction of Absorbed Photosynthetically Active Radiation (FA...
Article
Full-text available
This document intends to identify the requirements applicable to the calibration and validation (Cal/Val) activities for the optical missions of the Copernicus Space Component. These optical missions can be further classified as Surface Colour and Surface Temperature missions. Missions dedicated to atmosphere composition are addressed in a specific...
Article
Full-text available
The Sentinel-2 Level 2 Prototype Processor (SL2P) is made available to users for the retrieval of vegetation biophysical variables including leaf area index (LAI) from Multispectral Instrument (MSI) data within the Sentinel Application Platform (SNAP). A limited number of validation exercises have indicated SL2P LAI retrievals frequently meet user...
Article
Full-text available
This paper aims to assess the relationship between the surface reflectance derived from ground based and aircraft measurements. The parameters of the Rahman–Pinty–Verstraete (RPV) and Ross Thick-LiSparse (RTLS) kernel based bi-directional reflectance distribution functions (BRDF), have been derived using actual measurements of the hemispherical-dir...
Article
Full-text available
With a growing number of Earth observation (EO) products available through operational programmes such as the European Union's Copernicus, there is increasing emphasis on product accuracy and uncertainty, necessitating evaluation against in situ reference measurements. Whilst existing reference datasets have proven a valuable resource, they incorpo...
Conference Paper
Full-text available
Soil Moisture Product of the Ground-Based Observations for Validation (GBOV) of Copernicus Global Land Products Project Lopez-Baeza E 1 , Albero Peralta E 1 , Benlloch Casaban A 1 , Martinez Diaz B 1 , Asensi Ortega V 1 , Lerebourg C 2 , Bai G 2 , Ronco E 2 , Bruniquel V 2 , Gobron N 3 , Clerici M 3 , Lanconelli C 3 1 University of Valencia, Burj...
Article
Satellite remotely sensed fraction of photosynthetically active radiation (FPAR) products are widely used in land-surface monitoring and modeling, especially for estimating global terrestrial photosynthetic activity through light use efficiency (LUE) models. PAR absorbed by active chlorophyll (APARchl) is directly linked to vegetation photosynthesi...
Article
Full-text available
Surface albedo is a fundamental radiative parameter as it controls the Earth’s energy budget and directly affects the Earth’s climate. Satellite observations have long been used to capture the temporal and spatial variations of surface albedo because of their continuous global coverage. However, space-based albedo products are often affected by err...
Article
Full-text available
NOAA platforms provide the longest period of terrestrial observation since the 1980s. The progress in calibration, atmospheric corrections and physically based land retrieval offers the opportunity to reprocess these data for extending terrestrial product time series. Within the Quality Assurance for Essential Climate Variables (QA4ECV) project, th...
Conference Paper
The Copernicus Ground-Based Observations for Validation (GBOV) service aims to develop and distribute robust in-situ datasets from a selection of ground-based monitoring sites for a systematic and quantitative validation of Earth Observation (EO) land products. The EO land products of particular interest are those from the Copernicus Global Land Se...
Article
The High resOlution Land Atmosphere surface Parameters from Space (HOLAPS) programme provides a modeling system to maximize the use of satellite-based products and ensure internally consistent estimation of surface water and energy fluxes. Leaf area index (LAI) and land surface albedo are two key parameters for estimation of latent and sensible hea...
Article
Full-text available
Drought in Australia has widespread impacts on agriculture and ecosystems. Satellite-based Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) has great potential to monitor and assess drought impacts on vegetation greenness and health. Various FAPAR products based on satellite observations have been generated and made available to the...
Poster
Full-text available
Radiative forcings are modeled using 3 Earth Observation land surface albedo (MCD43C3, GlobAlbedo and Copernicus Global Land Services) and 5 burnt area (FireCCIv4, FireCCIv5, MCD45C5, MCD64C6 and Copernicus Global Land Services) products, and the ERA5 downward Solar radiation at the Surface. Results are summarized by vegetation cover type using the...
Poster
Full-text available
In this benchmark we present the comparison results between Sentinel-3 Synergy L2 reflectance and Sentinel-3 OLCI L2 rectified reflectances for the RED and NIR spectral bands. The methodology evaluates the spatial and temporal consistency of the correlation and bias in images over 3 areas characterised by different land cover types during a 6 month...
Poster
Full-text available
Satellite land-products require a continuous validation activity which is generally based on the comparison with reference surface observations. Despite the increasing efforts of the monitoring networks to adopt up-to-date observation strategies, a certain degree of uncertainty affects in-situ benchmark, as well as the remote sensing retrievals. Th...
Article
This paper presents a framework for assessing the physical consistency between time-series of several satellite-based surface albedo and burned area products at global scale. The methodology evaluates the level of agreement of temporal change between these two Essential Climate Variables (ECVs) taking into account their uncertainties. Several confi...
Article
Full-text available
Data from Earth observation (EO) satellites are increasingly used to monitor the environment, understand variability and change, inform evaluations of climate model forecasts, and manage natural resources. Policymakers are progressively relying on the information derived from these datasets to make decisions on mitigating and adapting to climate ch...
Article
Full-text available
In 2017, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-reached new record highs. The annual global average carbon dioxide concentration at Earth's surface for 2017 was 405.0 ± 0.1 ppm, 2.2 ppm greater than for 2016 and the highest in the modern atmospheric measurement record and in ice cor...
Article
Full-text available
This paper presents results of using multi-sensor and multi-angular constraints in the generic Earth Observation-Land Data Assimilation System (EO-LDAS) for reproducing arbitrary bandsets of hyperspectral reflectance at the top-of-canopy (TOC) level by merging observations from multispectral sensors with different spectral characteristics. This is...
Article
Full-text available
Application of remote sensing datasets in modelling phenology of heterotrophic animals has received little attention. In this work, we compare the predictive power of remote sensing versus temperature-derived variables in modelling peak flight periods of herbivorous insects, as exemplified by nocturnal moths. Moth phenology observations consisted o...
Preprint
Full-text available
Data from Earth Observation (EO) satellites are increasingly used to monitor the environment, understand variability and change, inform evaluations of climate model forecasts and manage natural resources. Policy makers are progressively relying on the information derived from these datasets to make decisions on mitigating and adapting to climate ch...
Conference Paper
This paper proposes benchmark of synergy products against third-party mission. This is based on a modified version of the gamma index that could be suitable for fitness-for-purpose assessment given that one can choose various criteria depending on applications. We present results for assessing the surface spectral consistency between atmosphericall...
Conference Paper
This paper proposes a benchmarking method for land products inter-comparison. This is based on a modified version of the gamma index that could be suitable for fitness-for-purpose assessment given that one can choose various criteria depending on applications. The method is first presented and then applied to several land ECVs. We also present resu...
Conference Paper
This paper presents a novel framework for assessing the physical consistency between two terrestrial Essential Climate Variables (ECVs) products retrieved from Earth Observation at global scale. The proposed methodology assesses for the level of temporal and spatial agreement between products of different ECV's by applying a multi-temporal data app...
Presentation
Full-text available
The Quality Assurance for Essential Climate Variables (QA4ECV, FP7 project n. 607405, www.qa4ecv.eu) project generates quality-assured multi-decadal Climate Data Records for 3 atmospheric ECV precursors (NO2, HCHO, and CO) and 3 land ECVs (albedo, LAI, and FAPAR), with full uncertainty metrics for every pixel ready for model ingestion. This paper...
Conference Paper
Full-text available
One of the objectives of the EU-FP7 project QA4ECV (Qual-ity Assurance for Essential Climate variables, www.qa4ecv.eu, under contract N o 607405) project is to produce a long and consistent data record of global surface albedo. Thus, level-1 and level-2 data from several sensors, namely NOAA-AVHRR, several geostationary satellites and MODIS have be...
Article
Full-text available
Global long-term Satellite-based leaf area index (LAI) products have been generated and applied widely for understanding the feedbacks between climate and terrestrial vegetation. However, these long-term LAI products are not internally consistent over time and also not consistent with each other, which means they might be not suitable for serving a...
Article
Full-text available
Ch 7. Regional Climates: f. Europe and the Middle East
Article
Full-text available
The Fraction of Absorbed Photosynthetically-Active Radiation (FAPAR) is an important parameter in climate and carbon cycle studies. In this paper, we use the Earth Observation Land Data Assimilation System (EO-LDAS) framework to retrieve FAPAR from observations of directional surface reflectance measurements from the Multi-angle Imaging SpectroRadi...
Article
Full-text available
This paper proposes a benchmarking method for assessing the level of spatio-temporal variability of Essential Climate Variable (ECV) products against a reference taking into account acceptance criteria in terms of intensity and physical distance tolerances. This is based on a modified version of the gamma index that could be suitable for fitness-fo...
Article
Full-text available
Earth observation (EO) land surface products have been demonstrated to provide a constraint on the terrestrial carbon cycle that is complementary to the record of atmospheric carbon dioxide. We present the Joint Research Centre Two-stream Inversion Package (JRC-TIP) for retrieval of variables characterising the state of the vegetation–soil system....
Chapter
EO-LDAS is a system that helps to interpret spectral observations over land surface to provide an optimal estimate of state variables. Several sensor observations can be used together despite their difference in spatial and spectral resolution and acquisition frequencies. The system is based on a variational data assimilation (DA) scheme together w...
Article
Full-text available
Earth Observation (EO) land products have been demonstrated to provide a constraint on the terrestrial carbon cycle that is complementary to the record of atmospheric carbon dioxide. We present the Joint Research Centre Two-stream Inversion Package (JRC-TIP) for retrieval of variables characterising the state of the vegetation-soil system. The syst...
Conference Paper
Full-text available
Validation of satellite-based retrievals of land surface albedo using in-situ measurements is essential to identify differences between them, to improve retrieval algorithms and to assess conformity to accuracy requirements. Differences between in-situ and satellite-based retrievals depend on the actual difference and their associated uncertainties...
Article
Full-text available
Land surface albedo defines the fraction of short-wave radiation reflected by the Earth's surface and controls the surface energy balance; thus, it is important for environmental and climate scientific communities. Remote sensing is the only means to globally map land surface albedo, however for it to be of use to the aforementioned communities, it...
Article
Full-text available
This report is the response to a request by the Committee on Space Research of the International Council for Science to prepare a roadmap on observation and integrated Earth-system science for the coming ten years. Its focus is on the combined use of observation sand modelling to address the functioning, predictability and projected evolution of in...
Conference Paper
This paper introduces a methodology to infer the physical consistency of different remote sensing satellite-based products using the gamma index metrics. In this work the capabilities of the gamma index as a suitable consistency indicator of different satellite products are shown. The method is used in order to support the Copernicus Climate Change...
Conference Paper
This paper presents the concept and first results of the Copernicus Climate Change Service Fitness-for-Purpose (C3S F4P) project. The main goal aims at evaluating the efficiency and overall performance of the service, mainly with regard to users information needs and high level requirements. This project will also assess the fitness-for- purpose of...
Conference Paper
The 4th MERIS data reprocessing should start in the first quarter of 2016. It is focused on the alignment, as far as possible, of the MERIS and Sentinel-3/OLCI data processing chains in order to ensure a continuity of the products derived from these two instruments. A major evolution of this reprocessing is related to the data formatting: the Envi...
Article
Full-text available
Satellite-based retrievals of land surface albedo are essential for climate and environmental modelling communities. To be of use, satellite-retrievals are required to comply to given accuracy requirements, mainly achieved through comparison with in situ measurements. Differences between in situ and satellite-based retrievals depend on their actual...
Article
Full-text available
The RAdiative transfer Model Intercomparison (RAMI) activity focuses on the benchmarking of canopy radiative transfer (RT) models. For the current fourth phase of RAMI, six highly realistic virtual plant environments were constructed on the basis of intensive field data collected from (both deciduous and coniferous) forest stands as well as test si...
Article
Full-text available
The RAdiative transfer Model Intercomparison (RAMI) activity focuses on the benchmarking of canopy radiative transfer (RT) models. For the current fourth phase of RAMI, six highly realistic virtual plant environments were constructed on the basis of intensive field data collected from (both deciduous and coniferous) forest stands as well as test si...
Conference Paper
Full-text available
The Earth Observation Land Data Assimilation System (EO-LDAS) is a system that allows interpreting spectral observations of the land surface to provide an optimal estimate of the Earth surface state. It allows a consistent combination of observations from different sensors despite the difference in spatial and spectral resolution and acquisition fr...
Conference Paper
Full-text available
EO-LDAS is a system that allows one to interpret spectral observations of the land surface to provide an optimal estimate of state of the Earth. It allows a consistent combination of observations from different sensors despite the difference in spatial and spectral resolution and acquisition frequencies. The system is based on a variational data as...
Article
Understanding the environmental and biotic drivers of respiration at the ecosystem level is a prerequisite to further improve scenarios of the global carbon cycle. In this study we investigated the relevance of physiological phenology, defined as seasonal changes in plant physiological properties, for explaining the temporal dynamics of ecosystem r...