Synthetic aperture radar sensitivity to forest changes: A simulations-based study for the Romanian forests

Natural and anthropogenic disturbances pose a significant threat to forest condition. Continuous, reliable and accurate forest monitoring systems are needed to provide earlywarning of potential declines in forest condition. To address that need, state-of-the-art simulationsmodelswere used to evaluate the utility of C-, L- and P-band synthetic aperture radar (SAR) sensors within an integrated Earth-Observation monitoring system for beech, oak and coniferous forests in Romania. The electromagnetic simulations showed differentiated sensitivity to vegetation water content, leaf area index, and forest disturbance depending on SAR wavelength and forest structure. C-band data was largely influenced by foliage volume and therefore may be useful for monitoring defoliation. Changes in water content modulated the C-band signal by b1 dBwhichmay be insufficient for a meaningful retrieval of drought effects on forest. Cband sensitivity to significant clear-cuts was rather low (1.5 dB). More subtle effects such as selective logging or thinning may not be easily detected using C- or L-band data with the longer P-band needed for retrieving small intensity forest disturbances. Overall, the simulations emphasize that additional effort is needed to overcome current limitations arising from the use of a single frequency, acquisition time and geometry by tapping the advantages of dense time series, and by combining acquisitions from active and passive sensors. The simulation results may be applicable to forests outside of Romania since the forests types used in the study have similar morphological characteristics to forests elsewhere in Europe.Romanian National Agency for Scientific Research and Innovation Authorit

The European Space Agency BIOMASS mission: Measuring forest above-ground biomass from space

The primary objective of the European Space Agency's 7th Earth Explorer mission, BIOMASS, is to determine the worldwide distribution of forest above-ground biomass (AGB) in order to reduce the major uncertainties in calculations of carbon stocks and fluxes associated with the terrestrial biosphere, including carbon fluxes associated with Land Use Change, forest degradation and forest regrowth. To meet this objective it will carry, for the first time in space, a fully polarimetric P-band synthetic aperture radar (SAR). Three main products will be provided: global maps of both AGB and forest height, with a spatial resolution of 200 m, and maps of severe forest disturbance at 50 m resolution (where “global” is to be understood as subject to Space Object tracking radar restrictions). After launch in 2022, there will be a 3-month commissioning phase, followed by a 14-month phase during which there will be global coverage by SAR tomography. In the succeeding interferometric phase, global polarimetric interferometry Pol-InSAR coverage will be achieved every 7 months up to the end of the 5-year mission. Both Pol-InSAR and TomoSAR will be used to eliminate scattering from the ground (both direct and double bounce backscatter) in forests. In dense tropical forests AGB can then be estimated from the remaining volume scattering using non-linear inversion of a backscattering model. Airborne campaigns in the tropics also indicate that AGB is highly correlated with the backscatter from around 30 m above the ground, as measured by tomography. In contrast, double bounce scattering appears to carry important information about the AGB of boreal forests, so ground cancellation may not be appropriate and the best approach for such forests remains to be finalized. Several methods to exploit these new data in carbon cycle calculations have already been demonstrated. In addition, major mutual gains will be made by combining BIOMASS data with data from other missions that will measure forest biomass, structure, height and change, including the NASA Global Ecosystem Dynamics Investigation lidar deployed on the International Space Station after its launch in December 2018, and the NASA-ISRO NISAR L- and S-band SAR, due for launch in 2022. More generally, space-based measurements of biomass are a core component of a carbon cycle observation and modelling strategy developed by the Group on Earth Observations. Secondary objectives of the mission include imaging of sub-surface geological structures in arid environments, generation of a true Digital Terrain Model without biases caused by forest cover, and measurement of glacier and icesheet velocities. In addition, the operations needed for ionospheric correction of the data will allow very sensitive estimates of ionospheric Total Electron Content and its changes along the dawn-dusk orbit of the mission

Forward and Inverse Modeling for Synthetic Aperture Radar Observables in Bistatic Configuration. Applications in Forest Remote Sensing

Forest observation worldwide is paramount in many fields of study, not only regarding environment applications - whether at a global or local scale (carbon cycle and climate stakes, ecosystems health) - but also towards anthropogenic activities (forestry, detection related to military or rescue purposes). Though vast, with about one third of earth’s land surface, its importance lies rather in its highly sensitive nature versus climate or human pressure, which thereby strengthen the need of observation and monitoring. Within this scope, remote sensing technique can’t be overlooked and takes truly part in a better understanding of Earth System Science. Prominent among these, radar is favoured by supplying its own illumination (as a active system) and by the all-whether as well as medium penetration capabilities of microwaves. Radar remote sensing is thereby particularly relevant to probe forest structure, all the more with the Pol-InSAR acquisition which enables to localize by means of the interferometric height retrieval, the polarimetric information about the medium scattering nature, and this on top of the imaging product. As testified by the fertile number of campaigns as well as studies to cope with its current limitations, one can truly assert the golden age of SAR use, among which the bistatic configuration comes within this scope of growing improvements. Although revisited several times, its potential towards forest remote sensing and by means of biPol-InSAR acquisition haven’t been assessed so far. Besides, the current resurgence for bistatic, favored by noticeable technical advances and well illustrated by several successful airbone and hybrid spaceborne campaigns makes the well known geometrical, opportunistic and discretion advantages of a receive only sensor more and more attractive. For all that, such acquisition haven’t been achieved yet in the framework of forest remote sensing (especially at suitable frequencies such as P or L band), our investigation will be thus based forward electromagnetic simulation. Indeed, the latter finds a great importance to understand and foresee the scattering behaviour, all the more that bistatic as well as forest diversity widen considerably the possible set of configurations. For that purpose, MIPERS -Multistatic Interferometric and Polarimetric model for Remote Sensing- based on a coherent and discrete formulation, has been developed to cope not only with the multistatic geometry -and the subsequent imaging constrains- but also with possible sparse forests including man-made structures by means of an original multi-zone approach. Theoretical validations but also confrontations with experimental monostatic data with temperate forests have been performed and emphasize - jointly to a sensitivity analysis - the importance of specific ground truth elements. Moreover, simulations have been achieved in order to set forth specific scattering behaviour intrinsic to a given bistatic geometry. On top of symmetry properties and polarization effects which turn out to be relevant to discriminate coherent and distributed targets (coming thereby with interesting detection applications), the sensitivity of the scattering mechanisms towards the bistatic configuration has been used with the aim of improving the main retrieval methods currently used in monostatic, that is the P-HV approach or the Pol-InSAR one. For the latter, an ad-hoc inversion scheme has been developed to cope not only with the extension to bistatic but also with an improved description of the forest model, particularly for what concerns the structured medium and the coupling terms between volume and ground scatterers. Whether for this quantitative inversion approach involving descriptive parameters or for biomass retrieval directly based on polarimetric radiometry, optimal bistatic configurations have been set forth in the light of simulations analysis, coming thereby with the planning of experimental campaigns as further prospects

Modélisation directe et inverse des observables radar à synthèse d'ouverture en configuration bistatique. Applications à la télédétection des milieux forestiers

Synthetic aperture radar (SAR) turns out to be particularly powerful in forest remote sensing, benefiting from micro-waves properties jointly to operational assets. Nevertheless, the interpretation of SAR measurements regarding in-situ parameters is not straightforward and originates many fields of research, such as the bistatic configuration. The success of recent airborne campaigns (e.g joint ONERA-DLR acquisition) or hybrid ones illustrates certain resurgence for bistatic, mostly fostered by system and strategic advantages. Yet, the physical potential of bistatic observables remains poorly known, particularly for forest monitoring. Initiated by that question, the thesis aims at investigating optimal bistatic configurations in order to ease and improve the retrieval problem, keeping in mind the operational feasibility. For such topic, electromagnetic modeling is of the greatest importance, as shown with the development of the simulator MIPERS which assets regarding existing models evince all their relevance for the understanding of the new observables. Based on theoretical and phenomenological results supported by our simulations, innovative extensions of monostatic reference algorithms based on the backscatter or on vectorial interferometry have been set forth, in order to estimate the biomass directly or through forest model descriptive parameters. On top of experimental bistatic campaigns, also set forward are promising prospects on multistatic acquisitions.Le radar à synthèse d'ouverture (RSO) constitue un instrument unique en télédétection des forêts, fort des propriétés physiques micro-ondes en sus d'atouts opérationnels. Néanmoins, l'utilisation de la sensibilité des mesures SAR aux variables d'intérêts in-situ n'est pas triviale et constitue de multiples axes de recherche dont l'étude de la configuration bistatique. Le succès de récentes acquisitions aéroportées (e.g campagne conjointe ONERA-DLR) ou hybrides témoigne d'une certaine résurgence pour la géométrie bistatique, principalement mis en avant pour des considérations opérationnelles. La question du potentiel physique des observables bistatiques reste cependant peu traitée. La thèse s'inscrit dans cet objectif, via l'étude de configurations bistatiques optimales pour améliorer l'inversion de paramètres in-situ d'intérêts, tout en considérant leur faisabilité. Dans ce cadre, la modélisation électromagnétique est fondamentale, illustrée ici par le développement du simulateur ad-hoc MIPERS dont les originalités par rapport aux modèles existants ont démontré toute leur importance pour analyser ces nouvelles observables. Des extensions novatrices des algorithmes de référence en monostatique basées sur l'intensité et l'interférométrie vectorielle pour une estimation directe de la biomasse ou via l'inversion de paramètres descriptifs de modèles de forêts sont alors proposées, à l'issue de formulations théoriques supportées par les résultats de simulations. Outre de futures campagnes expérimentales bistatiques, sont aussi mises en avant les perspectives innovantes de configurations multistatiques

La construction d’une Europe de la recherche et ses effets sur les relations scientifiques transatlantiques

International audienceDans les discours sur la science, les coopérations transatlantiques occupent une place importante depuis la deuxième guerre mondiale. Elles ont été souvent considérées sous deux angles : celui du rattrapage et celui de la formation. Les jeunes chercheurs vont aux Etats-Unis pour apprendre les nouvelles techniques (voire théories), pour accéder aux équipements de pointe ou pour se former, l’attrait du post-doctorat américain étant dans un certain nombre de disciplines assez fort.Ces visions diffèrent suivant les domaines, mais ce qui nous a frappé dans les relectures effectuées pour cette conférence, reste leur très grande stabilité sans que soient pris en compte deux phénomènes centraux : d’une part les quelques 60 ans de construction européenne, dans laquelle la science a souvent joué un rôle pilote ; et d’autre part l’évolution très forte des domaines scientifiques qui catalysent la croissance des activités scientifiques.Cette présentation se centre sur le domaine actuel qui catalyse la croissance des publications scientifiques, les nano sciences et technologies, pour poser la question de la place des relations transatlantiques dans les dynamiques à l’œuvre

On the use of virtual ground scatterers to localize double and triple bounce scattering mechanisms for bistatic SAR

International audienceIn Radar remote sensing, the electromagnetic (em) modeling of scattering contributions from natural or man-made scatterers has often to deal with coupling scattering mechanisms due to the underlying reflecting surface (ground or water). For the monostatic configuration, this contribution is commonly associated with the so-called double bounce scattering mechanism, which is also known to be located in synthetic aperture radar (SAR) images at the vertical projection of the scatterer onto the ground. To explore this phenomenon in the more general case of bistatic SAR but also for triple bounce scattering, a new formalism using virtual scatterers is introduced in this paper. Based upon image theory and on far-field assumption, these virtual points are defined by simple interaction scatterers located on the reflecting surface, and involving the same traveling wave path than the considered scattering mechanism. Depending only on the incidence and scattering angles, elegant formulae in their simplicity are highlighted to construct these fictitious scatterers. The resulting reduction of multiple to simple interaction scattering mechanisms simplifies the finding of their location within bistatic SAR images, generalizing thereby migration effects associated to coupling mechanisms in the bistatic configuration

Globalisation of corporate invention.

Communication consultable sur Internet : http://iri.jrc.ec.europa.eu/concord-2010/papers/schoen.pdfInternational audienceThe Corporate Invention Board project, which aims at characterizing the nature and the extent of technological globalisation, gives the possibility to track and analyze the transformation of global patents portfolio of industrial groups overtime. It also identifies the geographic origin of patents' protected inventions. The Corporate Invention Board complements the "Industrial R&D Investment Scoreboard" produced by Institute for Prospective Technological Studies. The industrial R&D Investment Scoreboard, an annual study of the European Commission, analyzes the performances of the 2000 industrial companies (1000 based within the European Union, 1000 outside) with the most important annual R&D investments. Through priority patents' statistics, the Corporate Invention Board focuses on the outputs of these R&D investments. Thus, the Corporate Invention Board provides information on technologies and on localisation of these investments. The Corporate Invention Board project has developed an original database which combines information extracted from the "Patstat" patent database and from the "Orbis" financial database. The first data compilation performed within the Corporate Invention Board project has demonstrated the feasibility of combining financial and patent data at a largescale for characterising corporate technological strategies. Additionally, a userfriendly access to Corporate Invention Board data has been proposed through a website (www.CorporateInventionBoard.eu). Two methodological adjustments, which will be implemented before summer 2010, should fix the main shortcoming

Measuring the globalisation of Corporate Invention

Synthèse de la communication consultable sur Internet : http://www.enid-europe.org/conference/abstracts/Schoen%20(innovation).pdfPublic policies regarding globalisation of R&D have a limited evidence base. Two major reasons explain that situation. In the first place, analysts in policy - and academics- circles are still far from understanding properly the dynamics of globalisation of industrial R&D (OECD 2008). How does a firm combine the various motives for locating its R&D locations? What are their respective weights? Many key questions remain to date unanswered. Secondly, the lack of quantitative and qualitative characterisation makes it often difficult for policy designer to go beyond anecdotal evidence; the quality of available data on R&D internationalization remains weak (IPTS 2007). This paper tackles this second difficulty. It focuses on the inventive component of R&D. It aims at characterising quantitatively to what extent firms make use of the global technological pool of competencies across the world rather than accessing knowledge locally relying on domestic proximity. This research uses an original very large data set for testing the main hypothesis explored in the field of international generation of technology concerning the structural and technological business features that facilitate the globalisation of R&D

Network characteristics of highly co-active researchers

Synthèse de la communication consultable sur Internet : http://www.cwts.nl/pdf/BookofAbstracts2010_version_15072010.pdfCo-activity, defined as a researcher joint production of scientific articles and patents of invention, is an interesting focus for studying how scientific and technological research networks connect. Building on Stefano Breschia and Christian Catalini's approach, this study analyses the research networks linking scientists working in an open science environment and researchers involved in the private technology domain. As the study previously mentioned, it combines data on scientific co-authorship with data on patent coinvention, at the level of individual researchers, for two science-intensive technology fields: heterogeneous catalysis and pharmaco-genomics. But this research departs from Breschia and Catalina's work in the process chosen for setting up of the body of data: i.e. in the delineation procedure. This research characterises at a finely grained level the scientific papers and patents produced by a group of core researchers, highly visible in their respective field, that are selected through an expert-based process

Bistatic Pol-InSAR Scenario and Evaluation By Forest Scattering Simulations

Performing estimation of height and extinction coe