58 research outputs found

    A NEW CLIMATOLOGY OF THE AEROSOLS BASED ON THEIR INHERENT OPTICAL PROPERTIES FOR THE MERIS ATMOSPHERIC CORRECTIONS OVER OCEAN

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    ABSTRACT In the classical scheme of atmospheric corrections over oceans, the derivation of aerosol path radiances in the visible region is achieved using aerosol models deduced from the spectral dependency of atmospheric signals in the near-infrared domain. Standard models are generally included in the aerosol climatology, but the latter is not sufficient to describe variety of aerosols encountered over coastal areas. One way to extend this climatology consists in the generation of additional models. Coastal and inland CIMEL stations from AERONET (AErosol RObotic NETwork) offer an extensive data set of aerosol characteristics in marine environment through solar extinction and sky radiance measurements. Data collected by 25 stations during several years have been processed with an iterative method of aerosol phase functions retrieval developed at ULCO, to build-up a very large database (~7000 sequences). Statistical methods applied on this data set allowed to discard the wrong sequences and to suggest a classification in aerosol models through their inherent optical properties

    Retrieval of pine forest biomass using JPL AIRSAR data

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    The analysis of Jet Propulsion Laboratory (JPL) Airborne Synthetic Aperture Radar (AIRSAR) data over the Landes forest in South-West France revealed strong correlation between L- and especially P-band sigma degrees and the pine forest biomass. To explain the physical link of radar backscatter to biomass, a polarimetric backscattering model was developed and validated. Then the model was used in a simulation study to predict sigma degree sensitivity to undesired canopy and environmental parameters. Main results concerning the data analysis, modeling, and simulation at P-band are reported

    Non-Hodgkin's lymphoma of the sino-nasal tract in children

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    Childhood head and neck cancers are relatively uncommon. Of all head and neck cancers occurring in children, non-Hodgkin\u2032s lymphoma (NHL) is the most common, others being rhabdomyosarcoma and nasopharyngeal carcinoma. In the head and neck region, sinuses are the second commonest primary site of NHL after neck lymph nodes. These can be of several different types depending on the predominant cell type and histologic appearance, the most common histological variant being diffuse large B-cell lymphoma. In an attempt to simplify the classification and to develop a universally acceptable classification and staging, they have been classified and staged numerous times over the last three decades, adding more confusion to the topic. Clinical presentations vary according to the histological type. The low grade lymphomas present with a nasal cavity or para-nasal sinus mass associated with obstructive symptoms and/or lymphadenopathy, while high grade lymphomas present with aggressive signs and symptoms including non-healing ulcer, epistaxis, septal perforation and bony destruction. The primary treatment consists of chemotherapy and / or radiation therapy, which is able to achieve remission in two-third of the patients, however, prognosis remains poor with cumulative five-year survival rates at about 30% for all the types of sino-nasal NHLs. Newer targeted therapy (monoclonal antibodies) and combination therapies (including stem cells) are currently being tested in order to improve survival rates in these patients. This article aims at providing an overview of clinico-epidemiologic characteristics, staging system currently in use, management, prognosis and possibilities of future research in the field of childhood sinonasal NHLs

    European Radiometry Buoy and Infrastructure (EURYBIA): A Contribution to the Design of the European Copernicus Infrastructure for Ocean Colour System Vicarious Calibration

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    In the context of the Copernicus Program, EUMETSAT prioritizes the creation of an ocean color infrastructure for system vicarious calibration (OC-SVC). This work aims to reply to this need by proposing the European Radiometry Buoy and Infrastructure (EURYBIA). EURYBIA is designed as an autonomous European infrastructure operating within the Marine Optical Network (MarONet) established by University of Miami (Miami, FL, USA) based on the Marine Optical Buoy (MOBY) experience and NASA support. MarONet addresses SVC requirements in different sites, consistently and in a traceable way. The selected EURYBIA installation is close to the Lampedusa Island in the central Mediterranean Sea. This area is widely studied and hosts an Atmospheric and Oceanographic Observatory for long-term climate monitoring. The EURYBIA field segment comprises off-shore and on-shore infrastructures to manage the observation system and perform routine sensors calibrations. The ground segment includes the telemetry center for data communication and the processing center to compute data products and uncertainty budgets. The study shows that the overall uncertainty of EURYBIA SVC gains computed for the Sentinel-3 OLCI mission under EUMETSAT protocols is of about 0.05% in the blue-green wavelengths after a decade of measurements, similar to that of the reference site in Hawaii and in compliance with requirements for climate studies

    Wind-induced resuspension in a shallow lake from Medium Resolution Imaging Spectrometer (MERIS) full-resolution reflectances

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    A lack of empirical evidence impedes assessment of the spatial and temporal extent of critical conditions for recurring high turbidity in large wind-exposed shallow lakes. Here spatiotemporal variation in total suspended matter (TSM) concentration was captured by processing 30 Envisat Medium Resolution Imaging Spectrometer (MERIS) images of a shallow lake (Markermeer) with a spectral matching algorithm. The TSM maps showed elevated downwind concentrations for moderate winds (from 4 to 9 m

    Scaling up Semi-Arid Grassland Biochemical Content from the Leaf to the Canopy Level: Challenges and Opportunities

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    Remote sensing imagery is being used intensively to estimate the biochemical content of vegetation (e.g., chlorophyll, nitrogen, and lignin) at the leaf level. As a result of our need for vegetation biochemical information and our increasing ability to obtain canopy spectral data, a few techniques have been explored to scale leaf-level biochemical content to the canopy level for forests and crops. However, due to the contribution of non-green materials (i.e., standing dead litter, rock, and bare soil) from canopy spectra in semi-arid grasslands, it is difficult to obtain information about grassland biochemical content from remote sensing data at the canopy level. This paper summarizes available methods used to scale biochemical information from the leaf level to the canopy level and groups these methods into three categories: direct extrapolation, canopy-integrated approach, and inversion of physical models. As for semi-arid heterogeneous grasslands, we conclude that all methods are useful, but none are ideal. It is recommended that future research should explore a systematic upscaling framework which combines spatial pattern analysis, canopy-integrated approach, and modeling methods to retrieve vegetation biochemical content at the canopy level
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