389 research outputs found
Aerosol Direct Radiative Effect in the Po Valley Region Derived from AERONET Measurements
The aerosol direct radiative effect (ADRE) affecting the Po Valley and the adjacent North Adriatic Sea is studied using 10-year series of measurements collected at two AERONET sites located in the western part of the Valley (Ispra), and on a platform (AAOT) offshore Venice. This region is characterized by a high, mostly continental, aerosol load with comparable average aerosol optical thickness (AOT) at both locations (0.21 at 500 nm) and more absorbing aerosols at Ispra. A dynamic aerosol model accounting for the changes in scattering phase function with AOT is used for radiative transfer calculations, together with boundary conditions representative of terrestrial and marine surfaces. A sensitivity analysis allows the construction of an error budget for the daily ADRE estimates, found to be of the order of 20% and
mostly due to uncertainties on aerosol single scattering albedo and AOT. The daily radiative efficiencies, normalized by AOT at 500 nm, increase from December to June, from -17 to -24 W m-2 AOT-1 at top-of-atmosphere (TOA) and -33 to -72 W m-2 AOT-1 at surface for the Po Valley, and from -15 to -32 (TOA) and -35 to -65 W W m-2 AOT-1 (surface) for the AAOT site. The average of log-transformed ADRE for TOA, surface and atmosphere are -5.2, -12.2 and +6.8 W m-2 for the Po Valley case, and -6.5, -13.0 and +6.5 W m-2 for the AAOT site but these values can be much higher for individual days. Concurrent clear-sky days give indications on the regional atmospheric heating spatial gradients.
Differences between the atmospheric ADRE at the two locations
average 6.3 W m-2 with a gradient positive towards the inner
valley in 65% of the cases. This study confirms the importance of
duly considering the radiative impact of aerosols on the regional
climate.JRC.H.3-Global environement monitorin
Assessment of Global Ocean Colour Products against In-situ Datasets
Ocean colour from satellite has given over the last two decades another dimension to ecosystem studies and marine biology, providing key information on the timing and spatial distribution of phytoplankton blooms, and the magnitude of primary production. Remote observations of ocean colour from space represent therefore a major tool directly related to the marine biogeochemical distributions and associated processes.
One of the goals of the European GMES Integrated Project MERSEA is to provide an accurate and consistent stream of ocean colour data, by exploiting the products made available in a number of individual missions launched by various space agencies. In this context, validation exercises, done via the direct comparison of satellite derived quantities with in situ measurements, represents a critical component in establishing the accuracy of the remotely-sensed data.
In this study we present a validation of Chlorophyll-a concentration derived from SeaWiFS and MODIS sensors, against in situ measurements retrieved from three different datasets (NODC, SeaBASS, JODC). The results of this comparison are well in line with previous analysis conducted on SeaWiFS, both from the point of view of the global statistics than for most of the regional results, and the uncertainties are lower than the value of 0.35 often considered as the objective for Chlorophyll-a distributions.
The SeaWiFS global average of RMS difference (for log-transformed values) shows an uncertainty of 0.29, while it is is slightly higher for MODIS (0.31), a difference likely partly due to a smaller statistical basis. The agreement is better for open ocean regions (RMSD reduced
to 0.26 and 0.27 for SeaWiFS and MODIS respectively) than for coastal areas.
An important objective of this work, that goes beyond the scope of the present report, was to develop the validation procedure and protocols for further analyses regularly reviewing validation results to take into account successive reprocessing and other sensors, as well as including additional in situ data sets.JRC.H.3-Global environement monitorin
Marine and Coastal Information Systems for Europe and Africa
Marine Information Systems for Europe (EMIS, http://emis.jrc.ec.europa.eu/) and Africa (AMIS, http://amis.jrc.ec.europa.eu/) have been recently developed at the Joint Research Centre of the European Commission to provide the Users with an appropriate set of bio-physical information, of importance to conduct water quality assessment, resource monitoring and climate change studies in the coastal and marine waters. These systems are simple and easy-to-use mapping tool applications, created for the publication and dissemination of African and European marine information via the web. Both systems rely mostly on Earth Observation data from optical and thermal sensors, processed according to standard (i.e., space agency-related) and in-house peer-reviewed algorithms, as well modeled data, to generate indicators for global diagnostic of the coastal state and analyses of changes in marine ecosystems. In addition, the systems supply the users with basic navigation and interrogation tools with a range of time-series and statistical analysis generated automatically in a format ready for publication / reporting, and enabling decision makers to make full and lasting use of this information.JRC.H.5-Land Resources Managemen
RTM-IDL 1.0. Unified Routines to Define a Coupled Water-atmosphere System and Drive Radiative Transfer Model (FEM, Hydrolight)
A set of IDL routines to define a coupled water-atmosphere system and to drive Radiative Transfer simulations is described. This application takes advantage of IDL 6.0 Object Oriented Programming features in order to allow unified description of the physical system, independent of the code to drive, and to ease the maintenance of and the adaptation to a specific model (FEM, Hydrolight, ...). A common library of routines to analyse the results of the simulations is also implemented.JRC.H.5-Rural, water and ecosystem resource
Representing Aerosol Optical Properties with Theoretical Modelling and Global Observations
Aerosols are an important factor in biogeochemical cycles, climate variability and air quality. In the context of monitoring the marine ecosystems, a proper definition of the inherent optical properties of the aerosols is needed to perform radiative transfer simulations. These are useful to build inversion schemes, that will quantify the aerosol load and type and define the spectral signature of the ocean surface, and to quantify the aerosol direct radiative effect. This report describes tools that link size distribution of aerosol particles, assumed homogeneous spheres, and refractive index to optical properties through Mie theory. Then, it provides a brief survey of generic aerosol models, that is completed by a broad review of the measurements that are relevant for the definition of aerosol optical properties.JRC.H.5-Rural, water and ecosystem resource
Application of an improved version of the erosion potential method in alpine areas
the assessment of erosive processes is of great importance in environmental engineering, resource management and land planning. in this paper the empirical approach known as erosion Potential Method (EPM) was improved to simplify the identifi- cation of the involved parameters. in addition, EPM suitability for alpine watersheds, where the average yearly temperature may be below 0°C, was discussed. the advantages of distributed ap- proaches rather than lumped methodologies were tested. EPM was then implemented in a distributed form for a set of 31 catch- ments located in alta valtellina (northern italy) in order to cap- ture the spatial variability of the parameters and the intensity of the erosion processes. the results obtained for these catchments were positively compared to long-term sedimentation data from three reservoirs and from a turbidimetric station
CCD-based imaging and 3D space--time mapping of terahertz fields via Kerr frequency conversion
We investigate the spatially and temporally resolved four-wave mixing of terahertz (THz) fields and optical pulses in large-bandgap dielectrics, such as diamond. We show that it is possible to perform beam profiling and spaceâtime resolved mapping of THz fields by encoding the spatial information into an optical signal, which can then be recorded by a standard CCD camera
Robot-aided therapy for upper limbs in patients with stroke-related lesions. Brief report of a clinical experience
This study was aimed at verifying the improvement on the motor impairment and functionality in 19 patients with chronic hemiparesis after stroke treated with a robot-aided rehabilitation protocol using the ReoGoâą system (Motorika Medical Ltd, Israel), and at evaluating the persistence of the effects after 1 month. The study also focused on the actual possibility of administering the robot-aided therapy with the ReoGoâą for the upper limbs and on the patients' degree of acceptance and compliance with the treatment. Subjects underwent an assessment prior to the start of the rehabilitation project (T-1), one at the start (T0), one at the end of the treatment (T1) and one after one month from the end of the treatment (T2). The following tests were administered: (i) Fugl-Meyer (FM) upper limb; Ashworth scale (AS); Functional Independence Measure (FIMâą) (T-1 - T2); (ii) strength evaluation; Visual Analogue Scale (VAS) for pain; Frenchay Arm test (FAT); Box and Block test (BBT); Timed Up and Go (TUG) test (T0 - T2). Additionally, the Euro-QoL questionnaire and a VAS for the treatment satisfaction were administered to the subjects. Non-statistical difference of scores at T-1 and T0 on almost the entire battery of tasks suggested a stable patients' performance prior to the start of the rehabilitation. With the exception of the Medical Research Council (MRC) and the AS sub-scales measuring -as appropriate- strength and spasticity of the shoulder, triceps and wrist, all scores showed a significant increase between T0 and T1. The improvement on the pain could not be proved significant (p = 0.10). A significant increase between T0 and T2 was found for all assessment scores, with the exception of the MRC for external shoulder rotators (p = 0.05) and of the AS for shoulder (p = 0.32) and wrist (p = 0.08). Substantial stability was observed between T1 and T2. Patients were capable of completing the treatment and showed good participant satisfaction. This pilot study led to the finding of a clinical improvement and excellent patients compliance. It is possible that the learning process experienced by the patients was robot-dependent, especially in consideration of the general maintenance of the achievements observed on all activities
Terahertz Faraday rotation in a magnetic liquid: High magneto-optical figure of merit and broadband operation in a ferrofluid
We report on the demonstration of a high figure of merit (FOM) Faraday rotation in a liquid in the terahertz (THz) regime. Using a ferrofluid, a high broadband rotation (11 mrad/mm) is experimentally demonstrated in the frequency range of 0.2â0.9 THz at room temperature. Given the low absorption of the liquid, a high magneto-optical figure of merit (5-16ârad.cm/T) is obtained
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