TERRISCOPE: AN OPTICAL REMOTE SENSING RESEARCH PLATFORM USING AIRCRAFT AND UAS FOR THE CHARACTERIZATION OF CONTINENTAL SURFACES

ONERA is developing TERRISCOPE, a new platform to characterize the environment and the continental surfaces by optical remote sensing using manned aircrafts and UAS (Unmanned Airborne System). The objective of TERRISCOPE is to make available to the scientific community combinations of optical measurements remotely sensed with the best level state-of-the-art sensors. Different kinds of sensors have already been acquired or are still being acquired: Hyperspectral sensors (0.5–2.5 μm range), visible high resolution cameras, multispectral infrared cameras and airborne laser scanners. Each sensor is declined in two versions: one high performance for manned aircrafts and one more compact for UAS. This paper describes the whole equipment, and presents the main characteristics and performances of the carriers, the sensors and the processing chain. Possible sensors combinations on airplanes and UAS are also presented, as well as preliminary results

Emergent Functional Properties of Neuronal Networks with Controlled Topology

The interplay between anatomical connectivity and dynamics in neural networks plays a key role in the functional properties of the brain and in the associated connectivity changes induced by neural diseases. However, a detailed experimental investigation of this interplay at both cellular and population scales in the living brain is limited by accessibility. Alternatively, to investigate the basic operational principles with morphological, electrophysiological and computational methods, the activity emerging from large in vitro networks of primary neurons organized with imposed topologies can be studied. Here, we validated the use of a new bio-printing approach, which effectively maintains the topology of hippocampal cultures in vitro and investigated, by patch-clamp and MEA electrophysiology, the emerging functional properties of these grid-confined networks. In spite of differences in the organization of physical connectivity, our bio-patterned grid networks retained the key properties of synaptic transmission, short-term plasticity and overall network activity with respect to random networks. Interestingly, the imposed grid topology resulted in a reinforcement of functional connections along orthogonal directions, shorter connectivity links and a greatly increased spiking probability in response to focal stimulation. These results clearly demonstrate that reliable functional studies can nowadays be performed on large neuronal networks in the presence of sustained changes in the physical network connectivity

Cartographie de l'épaisseur des sols sous couvert forestier

Ce rapport a pour objectif de permettre à une autre personne de reprendre le travail déjà effectué sur la problèmatique de la cartographie de l'épaisseur des sols dans le bassin versant de Saint-Jean-du gard. Au cours de cette étude des choix ont été faits et des hypothèses explorées afin de préciser le sens des recherches et la méthode à suivre. Ce travail a permis l'établissement d'un système expert et au commencement de la mise en application de ce dernier. Pour atteindre ce point, différentes étapes, explicitées dans ce rapport, ont été franchies. Chacune a été plus ou moins approfondie et développée selon un compromis entre le temps et l'objectif recherché. ce travail devait être essentiellement exploratoire et avait pour but de poser les bases nécessaires à l'étude en affinant la problèmatique ainsi que la méthode pour y répondre et commencer sa réalisation dans l'idée d'être repris ensuite

Observing at-surface irradiance and albedo from space: The Tibet experiment

Monitoring the solar radiation budget on a daily basis is a prerequisite to study land surface processes, especially in climatology and hydrology, and in derived applications like drought early warning. Current space-born radiometers can provide daily observations to derive surface radiative fluxes at a spatial resolution of one square kilometer at best, which is not enough to properly take into account surface heterogeneity in many regions of the globe. As part of a major scientific initiative to study the hydrology of the Tibetan Plateau -especially known for its rough topography- this thesis focuses on developing a method to adequately estimate at-surface daily solar radiation budget over this particular area. Following a first effort to produce a time series of the radiative budget from existing satellite data products, it appeared that it is necessary to consider terrain and clouds spatial variability at the sub-pixel level when working over heterogeneous areas such as the Tibetan Plateau. Thus, the impact of spatial and temporal variability of clouds on solar radiation was investigated through a case study conducted on the field whose results demonstrate that the surface irradiance estimation would benefit from using cloud distribution instead of cloud fraction to account for the cloud cover. Furthermore, a high temporal resolution cloud cover leads to a better temporal average of the radiative fluxes. Regarding the effects of the terrain, a new sub-pixel topographic correction method is proposed and applied. It demonstrates that the integration of the sub-pixel topographic effects using high resolution DEM improves the irradiance as well as the albedo retrieval. The temporal resolution of the latter is also to consider and the use of geostationary satellite allows to increase the retrieval frequency. Based on multi-source and multi-resolution remote sensing data, the developed method provides a usable solar radiation budget dataset. Combined with the outcomes of the in-depth researches on clouds and topography, it paves the way for a new operational methodology which adequately accounts for sub-pixel heterogeneity when producing large area time series of solar radiation budget at the surface.Geoscience and Remote SensingCivil Engineering and Geoscience

Quantifying the impact of cloud cover on ground radiation flux measurements using hemispherical images

Linking observed or estimated ground incoming solar radiation with cloud coverage is difficult since the latter is usually poorly described in standard meteorological observation protocols. To investigate the benefits of detailed observation and characterization of cloud coverage and distribution, a fieldwork campaign has been set up in order to collect data about cloud cover conditions and daily evolution to directly analyse their impacts on solar radiation fluxes. To do so, daytime hemispherical images have been collected at a very high frequency, simultaneously to ground measurements of solar radiation fluxes in a scientific station close to Lake NamCo, China. After calibration, one of the main tasks was the classification of those hemispherical images and the extraction of meaningful indices to describe the cloud cover, such as cloud fraction or cloud cover distribution. The classification is based on automatic detection of threshold on the red channel histogram. The results show that several cloud indices could be successfully derived from the hemispherical images, even if very thin clouds can be difficult to detect. The indices are then correlated to the measured solar radiation values and the impact of cloud cover on surface radiation fluxes were analysed. This analysis highlights that, more than the cloud fraction, the cloud distribution in the hemisphere is of importance when modelling radiation fluxes in the solar domain

Multi-annual data products on turbulent heat fluxes at the local and continental scale using AATSR and fy-2 data

This paper summarizes the results of studies carried in the framework of the Dragon 2 Program - Project 5322 Key Eco-Hydrological Parameters Retrieval and Land Data Assimilation System Development in a Typical Inland River Basin of Chinas Arid Region. The investigations were focused on monitoring the fluxes of energy and water at the land-atmosphere interface across a range of spatial scales, using multi-spectral radiometric data collected by space-borne imaging radiometers. At the local scale a new approach to parameterize heat and vapour fluxes was developed and applied using Computational Fluid Dynamics to describe state and dynamics of the boundary layer over the heterogeneous and 3D structured land surface. An airborne scanning LIDAR was used to capture in detail surface geometry. Over the large area of the Qinghai-Tibet Plateau a land-atmospheric model was used to characterize the atmospheric Planetary Boundary Layer. The effect of land surface heterogeneity and structure on the exchange of heat and water was captured using the bi-angular observations of brightness temperature provided by the AATSR imaging radiometer. The heat and water flux densities were calculated hourly with Feng-Yun C, D and E VISSR data over the Qinghai-Tibet Plateau and the headwaters of main rivers around it.</p

Simultaneous enrichment and optical detection of low levels of stressed Escherichia coli O157:H7 in food matrices

International audienceAims: Rapid detection of enterohaemorrhagic E. coli O157:H7 in large range of stress conditions occurring in food processing. Methods and Results: Detection of E. coli O157:H7 in various food processing stress conditions using surface plasmon resonance imaging (SPRi) technique on an antibody microarray was evaluated. The direct detection method based on the culture/capture/measure (CCM) process consists of detecting bacteria during an enrichment step, which significantly decreases the overall assay duration. In optimized culture conditions, this method allows the specific detection of low CFU ml À1 in <7 h. Detection of bacteria directly in contaminated food samples was also conducted. Conclusions: The CCM technique using an antibody microarray is a label-free immunoassay that allows rapid detection of E. coli O157:H7 in both food processing stress conditions and complex food matrices. Significance and Impact of the Study: The assay is promising for detecting E. coli O157:H7 at different steps of food and drink processing and during storage. SPRi appears to be a suitable and powerful detection method for routine quality controls in food industry with important economic and societal impact

Improved Surface Reflectance from Remote Sensing Data with Sub-Pixel Topographic Information

Several methods currently exist to efficiently correct topographic effects on the radiance measured by satellites. Most of those methods use topographic information and satellite data at the same spatial resolution. In this study, the 30 m spatial resolution data of the Digital Elevation Model (DEM) from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) are used to account for those topographic effects when retrieving land surface reflectance from satellite data at lower spatial resolution (e.g., 1 km). The methodology integrates the effects of sub-pixel topography on the estimation of the total irradiance received at the surface considering direct, diffuse and terrain irradiance. The corrected total irradiance is then used to compute the topographically corrected surface reflectance. The proposed method has been developed to be applied on various kilometric pixel size satellite data. In this study, it was tested and validated with synthetic Landsat data aggregated at 1 km. The results obtained after a sub-pixel topographic correction are compared with the ones obtained after a pixel level topographic correction and show that in rough terrain, the sub-pixel topography correction method provides better results even if it tends to slightly overestimate the retrieved land surface reflectance in some cases.Geoscience & Remote SensingCivil Engineering and Geoscience