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Gobron N.,European Commission - Joint Research Center Ispra | Belward A.,European Commission - Joint Research Center Ispra | Pinty B.,European Commission - Joint Research Center Ispra | Pinty B.,Earth Observation Directorate | Knorr W.,University of Bristol
Geophysical Research Letters | Year: 2010

Earth Observation from space offers the opportunity to produce time-series of geophysical products that can be used to assess the state and changes of land surfaces. The Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) is used to monitor the state and evolution of terrestrial vegetation, and also constitutes a state variable in advanced Earth system models that contain a detailed enough description of the terrestrial biosphere. This present study reports a 12-year (1998-2009) time series of FAPAR derived from the combination of two satellite-based sensors. We find that FAPAR exhibits large-scale inter-annual variations and multi-year trends. The fraction of land grid cells showing positive anomalies, as computed by the deviation from the 12-year climatology, shows a rapid decrease in the early part of the analysis period (until 2004). Large negative anomalies can be associated with previously reported large-scale climate events, such as global land drying associated with El Nio Southern Oscillation 2000-2003, or the European drought of 2003 or recent Australian droughts The present analysis demonstrates that FAPAR is an important global variable suitable for large-scale monitoring of climate impacts on the terrestrial biosphere. Copyright 2010 by the American Geophysical Union.

Casadio S.,Serco | Arino O.,Earth Observation Directorate | Minchella A.,R.Ø.S.A.
Remote Sensing of Environment | Year: 2012

A method for the monitoring of night-time gas flaring of off-shore oil/gas extraction platforms using measurements of the Along Track Scanning Radiometer (ATSR) and the Synthetic Aperture Radar (SAR) is presented and discussed in detail. The positions of off-shore extraction sites are accurately estimated by using SAR data, while the flaring activity is estimated from night-time shortwave infrared (SWIR) radiance measured by ATSR. The North Sea area has been selected as test case and related flaring activity from 1991 to 2010 has been analysed at single site and at North Sea area scales. Results indicate a decline in the overall flaring activity during the time period considered in this work, although single sites can show positive flaring trends. The ATSR derived flaring time series has been compared to the crude oil production data provided by the US Energy Information Administration (EIA), showing very good agreement in terms of trend and seasonal behaviour. We present a simple inversion scheme aimed at the evaluation of the flame parameters (temperature and size) from night-time shortwave, middle and thermal infrared ATSR measurements, and results are discussed in detail. Finally, the possibility to estimate flaring efficiency from satellite measurements and from detailed technical information on flaring devices is envisaged. The proposed approach can be easily extended to other areas in which gas flaring from off-shore oil and gas extraction are an important economic and environmental factor. © 2012 Elsevier Inc.

Casadio S.,Serco | Arino O.,Earth Observation Directorate
Advances in Space Research | Year: 2011

The South Atlantic Anomaly (SAA) has been monitored for 19 years using the Along Track Scanning Radiometer (ATSR) series of instruments onboard the ERS-1, ERS-2 and ENVISAT ESA satellites. The time evolution of the night-time particle induced noise in the short wavelength infrared (SWIR, 1.6 μm) and visible (VIS, 0.55 μm) channels of the ATSR instrument series have been analysed. The monthly location and extension of the SAA are inferred by fitting a two-dimensional, elliptical Gaussian function to the coordinates of the night-time hot spots detected over the SAA region. The location of the centre of the SAA is found to drift westwards with an average drift rate of about 0.24 deg/year and northward with an average drift rate of about 0.12 deg/year. Irregularities are found where the drift speed is inverted and the SAA moves eastward and southward. Results indicate that, as expected, the retrieved values of SAA's strength and extension are anti-correlated with the solar activity expressed by the solar flux at 10.7 cm (F10.7). Finally, the peak-to-peak amplitude of the seasonal variation of the SAA strength, estimated from monthly VIS data, is found to be 30% of the average value with the annual to semiannual amplitude ratio of 1.38. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.

Berger M.,Earth Observation Directorate | Moreno J.,University of Valencia | Johannessen J.A.,Nansen Environmental and Remote Sensing Center | Johannessen J.A.,University of Bergen | And 2 more authors.
Remote Sensing of Environment | Year: 2012

The spatial and temporal characteristics of the new Sentinel missions, primarily designed to provide routine multidisciplinary observations for operational services, are also very suitable for addressing some of the challenges associated with advancing Earth System sciences. The Sentinels are ensuring long-term observational commitment and will operate a range of instruments with different spectral bands and spatial resolutions with global coverage and high revisit times. The complexity of Earth System models has been increasing gradually and most simulations of future climate and Earth system evolution are based on coupled models that include aspects of physics, bio/geo-chemistry, anthropogenic impacts and even recently some elements of socioeconomic factors. Sentinels will provide unique observations to describe such coupled atmosphere, oceans, land and cryosphere and the exchanges among them into Earth System models. This paper emphasizes the indispensable value of the data provided by the family of Sentinel constellations in the context of the urgent need for improved process understanding of the Earth system. © 2012 Elsevier Inc.

Rast M.,Earth Observation Directorate | Johannessen J.,Nansen Environmental and Remote Sensing Center | Mauser W.,Ludwig Maximilians University of Munich
Surveys in Geophysics | Year: 2014

Water is our most precious and arguably most undervalued natural resource. It is essential for life on our planet, for food production and economic development. Moreover, water plays a fundamental role in shaping weather and climate. However, with the growing global population, the planet's water resources are constantly under threat from overuse and pollution. In addition, the effects of a changing climate are thought to be leading to an increased frequency of extreme weather causing floods, landslides and drought. The need to understand and monitor our environment and its resources, including advancing our knowledge of the hydrological cycle, has never been more important and apparent. The best approach to do so on a global scale is from space. This paper provides an overview of the major components of the hydrological cycle, the status of their observations from space and related data products and models for hydrological variable retrievals. It also lists the current and planned satellite missions contributing to advancing our understanding of the hydrological cycle on a global scale. Further details of the hydrological cycle are substantiated in several of the other papers in this Special Issue. © 2014 Springer Science+Business Media Dordrecht.

Ciappa A.,Earth Observation Directorate | Pietranera L.,Earth Observation Directorate
Journal of Marine Systems | Year: 2013

In this study we analysed a combination of high and coarse resolution X-band COSMO-SkyMed Synthetic Aperture Radar (SAR) scenes collected during two periods in July and September 2011 over the Terra Nova Bay (Antarctica). High resolution (5m per pixel) and lower resolution SAR (100m) acquired over intervals of the order of minutes provided both, fine details and a full large-scale view of the polynya. The analysis was supported by several Ice Surface Temperature (IST) maps per day obtained from the thermal band of Moderate Resolution Imaging Spectroradiometer (MODIS) and some additional C-band Envisat Advanced SAR (ASAR) scenes available during the July period. The dataset revealed two major openings around 2000km2 occurred in the July period and one opening around 2500km2 in the September period. The SAR analysis revealed that the polynya area is clearly distinguished from the sea ice pack offshore during the growing and closing phase. During the opening phase, the open polynya area was characterized by newly formed frazil ice organized as ice streaks parallel to the wind direction and separated by a distance of between 300 and 800m. Waves of length between 30 and 70m were noted on the streaks of frazil ice and on the frazil and grease ice accumulated at the polynya border. The early stage of the growing phase was indicated by the uniform distance of the ice streaks near the border of the polynya, while convergence was an indication that the wind was slowing down and that the growing phase was at a late stage. The closing phase was characterized by the progressive freezing of the open polynya area from the downwind border toward the coast. The results of this analysis suggest that the detection of the polynya area from thermal infrared or microwave temperatures is more effective during the growing phase, when large areas of unfrozen water are present within the polynya, than during the closing phase when large areas of thin sea-ice prevail. © 2012 Elsevier B.V.

Padovani P.,European Southern Observatory | Giommi P.,Earth Observation Directorate | Rau A.,Max Planck Institute for Extraterrestrial Physics
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2012

We study the quasi-simultaneous near-IR, optical, ultraviolet and X-ray photometry of 11 γ -ray selected blazars for which redshift estimates larger than 1.2 have been recently provided. Four of these objects turn out to be high-power blazars with the peak of their synchrotron emission between ~3 × 10 15 and ~10 16 Hz, and therefore of a kind predicted to exist but never seen before. This discovery has important implications for our understanding of physical processes in blazars, including the so-called 'blazar sequence', and might also help in constraining the extragalactic background light through γ -ray absorption since two sources are strongly detected even in the 10-100 GeV Fermi-LAT band. Based on our previous work and their high powers, these sources are very likely high-redshift flat-spectrum radio quasars, with their emission lines swamped by the non-thermal continuum. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Ciappa A.,Earth Observation Directorate | Pietranera L.,Earth Observation Directorate | Battazza F.,ASI
Remote Sensing of Environment | Year: 2010

The Perito Moreno Glacier (Los Glaciares National Park, Patagonia, Argentina) ice stream has been investigated using X-band SAR amplitude images collected from February to December 2009 (excluding June) at time intervals of 8 and 16. days by the COSMO SkyMed satellites. The high spatial resolution dataset (10 × 10. km swath, 1. m per pixel) reveals many details of the glacier surface and the ice velocity fields extracted from sequential image pairs by the maximum cross-correlation method cover most of the glacier area. The efficiency of the cross-correlation method improves with high spatial resolution imagery and the co-registration error of the image pair also reduces. The glacier motion detected in the period shows variability on the time scale considered, evidencing the areas of higher dynamics under different speed regimes. © 2010 Elsevier Inc.

Giommi P.,Earth Observation Directorate | Giommi P.,National institute for astrophysics | Padovani P.,National institute for astrophysics | Padovani P.,European Southern Observatory | And 2 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2013

We have recently proposed a new simplified scenario where blazars are classified as flat spectrum radio quasars (FSRQs) or BL Lacs according to the prescriptions of unified schemes, and to a varying combination of Doppler-boosted radiation from the jet, emission from the accretion disc, the broad line region and light from the host galaxy. Here we extend our approach, previously applied to radio and X-ray surveys, to the γ-ray band and, through detailed Monte Carlo simulations, compare our predictions to Fermi-Large Area Telescope (LAT) survey data. Our simulations are in remarkable agreement with the overall observational results, including the percentages of BL Lacs and FSRQs, the fraction of redshift-less objects and the redshift, synchrotron peak and γ-ray spectral index distributions. The strength and large scatter of the oft-debated observed γ-ray-radio flux density correlation are also reproduced. In addition, we predict that almost 3/4 of Fermi-LAT BL Lacs, and basically all of those without redshift determination, are actually FSRQs with their emission lines swamped by the non-thermal continuum and as such should be considered. Finally, several of the currently unassociated high Galactic latitude Fermi sources are expected to be radio-faint blazars displaying a pure elliptical galaxy optical spectrum. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Pittori C.,Earth Observation Directorate | Pittori C.,National institute for astrophysics
Nuclear Physics B - Proceedings Supplements | Year: 2013

AGILE is a scientific mission of the Italian Space Agency (ASI) with INFN, INAF e CIFS participation, devoted to gamma-ray astrophysics. The satellite is in orbit since April 23rd, 2007. Gamma-ray astrophysics above 100 MeV is an exciting field of astronomical sciences that has received a strong impulse in recent years. Despite the small size and budget, AGILE produced several important scientific results, among which the unexpected discovery of strong and rapid gamma-ray flares from the Crab Nebula. This discovery won to the AGILE PI and the AGILE Team the prestigious Bruno Rossi Prize for 2012, an international recognition in the field of high energy astrophysics. We present here the AGILE data center main activities, and we give an overview of the AGILE scientific highlights after 5 years of operations. © 2013 Elsevier B.V.

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