The Experts below are selected from a list of 2151 Experts worldwide ranked by ideXlab platform
Djr Cherney - One of the best experts on this subject based on the ideXlab platform.
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urea and composted cattle manure affect forage yield and nutritive value in sandy soils of south central vietnam
Grass and Forage Science, 2018Co-Authors: Keenan C Mcroberts, Quirine M. Ketterings, D Parsons, T T Hai, N H Quan, Charles F Nicholson, Djr CherneyAbstract:Improved forage management can support increased production in smallholder beef systems. Our objective was to evaluate the effects of mineral nitrogen (urea) and composted cattle manure on Brachiaria cv. Mulato II yield and nutritive value in south-central coastal Vietnam. Study design was a randomized complete block on six farms (blocks), with treatments derived from the factorial combination of five rates of composted cattle manure (0, 4, 8, 12 and 24 Mg DM ha -1 year -1 ) and three urea rates (0, 60 and 120 kg N ha -1 year -1 ), split into six yearly applications. Yield was measured from 2011 to 2013 with 36-day average harvest intervals. Forage nutritive value was measured in September 2011 and December 2012. Highest yields were achieved when both compost and urea were applied at high rates. The initial yield and tiller responses to urea application were not sustained over the duration of the study when no compost was applied. Compost applied in isolation did not increase yield. Compost application increased Ash Concentration. Urea increased nutrient yield for all forage nutritive value parameters measured. Composted cattle manure combined with urea benefits grass yield, but high application rates are needed for sustained high yields on sandy soils.
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Urea and composted cattle manure affect forage yield and nutritive value in sandy soils of south‐central Vietnam
Grass and Forage Science, 2017Co-Authors: Keenan C Mcroberts, Quirine M. Ketterings, D Parsons, T T Hai, N H Quan, Charles F Nicholson, Djr CherneyAbstract:Improved forage management can support increased production in smallholder beef systems. Our objective was to evaluate the effects of mineral nitrogen (urea) and composted cattle manure on Brachiaria cv. Mulato II yield and nutritive value in south-central coastal Vietnam. Study design was a randomized complete block on six farms (blocks), with treatments derived from the factorial combination of five rates of composted cattle manure (0, 4, 8, 12 and 24 Mg DM ha -1 year -1 ) and three urea rates (0, 60 and 120 kg N ha -1 year -1 ), split into six yearly applications. Yield was measured from 2011 to 2013 with 36-day average harvest intervals. Forage nutritive value was measured in September 2011 and December 2012. Highest yields were achieved when both compost and urea were applied at high rates. The initial yield and tiller responses to urea application were not sustained over the duration of the study when no compost was applied. Compost applied in isolation did not increase yield. Compost application increased Ash Concentration. Urea increased nutrient yield for all forage nutritive value parameters measured. Composted cattle manure combined with urea benefits grass yield, but high application rates are needed for sustained high yields on sandy soils.
Simona Scollo - One of the best experts on this subject based on the ideXlab platform.
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maximum likelihood retrieval of volcanic Ash Concentration and particle size from ground based scanning lidar
IEEE Transactions on Geoscience and Remote Sensing, 2018Co-Authors: Luigi Mereu, Simona Scollo, Antonella Boselli, Saverio Mori, G Leto, F S MarzanoAbstract:An inversion methodology, named maximum-likelihood (ML) volcanic Ash light detection and ranging (Lidar) retrieval (VALR-ML), has been developed and applied to estimate volcanic Ash particle size and Ash mass Concentration within volcanic plumes. Both estimations are based on the ML approach, trained by a polarimetric backscattering forward model coupled with a Monte Carlo Ash microphysical model. The VALR-ML approach is applied to Lidar backscattering and depolarization profiles, measured at visible wavelength during two eruptions of Mt. Etna, Catania, Italy, in 2010 and 2011. The results are compared with those of Ash products derived from other parametric retrieval algorithms. A detailed comparison among these different retrieval techniques highlights the potential of VALR-ML to determine, on the basis of a physically consistent approach, the Ash cloud area that must be interdicted to flight operations. Moreover, the results confirm the usefulness of operating scanning Lidars near active volcanic vents.
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Volcanic Ash Concentration during the 12 August 2011 Etna eruption
Geophysical Research Letters, 2015Co-Authors: Simona Scollo, Antonella Boselli, Mauro Coltelli, Giuseppe Leto, Gianluca Pisani, Michele Prestifilippo, Nicola Spinelli, Xuan WangAbstract:Mount Etna, in Italy, is one of the most active volcanoes in the world and an ideal laboratory to improve volcano Ash monitoring and forecasting. During the volcanic episode on 12 August 2011, an eruption column rose up to several kilometers above sea level (asl), and the volcanic plume dispersed to the southeast. From the video-surveillance system, we were able to estimate variations in the column height (peak value of 9.5 ± 0.5 km above sea level) with time. We derived the time-varying discharge rate (peak value of 60 m3 s−1) and determined the Ash Concentration using a volcanic Ash dispersal model. The modeled Ash Concentration was compared with lidar measurements using different particle effective radius, and differences are within the error bars. Volcanic Ash Concentrations range from 0.5 to 35.5 × 10−3 g m−3. The comparison highlights that to improve volcanic Ash forecasting during volcanic crises it is necessary to take into account the time-varying discharge rate of explosive eruptions.
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A statistical approach to evaluate the tephra deposit and Ash Concentration from PUFF model forecasts
Journal of Volcanology and Geothermal Research, 2010Co-Authors: Simona Scollo, Mauro Coltelli, Michele Prestifilippo, Rorik Peterson, G. SpataAbstract:Abstract In this paper we present a new statistical approach which provides tephra deposit load and Ash Concentration using PUFF, a Lagrangian model widely used to forecast volcanic Ash dispersal during volcanic crisis. We perform a parametric study in order to analyze the influence of each input parameter on model outputs. For this test, we simulate two eruptive scenarios similar to the 2001 ( Scenario 1 ) and 1998 ( Scenario 2 ) Etna eruptions using high resolution weather data and a domain of 170 × 170 km. Results show that for both scenarios, we are able to calculate the tephra deposit load and Ash Concentration but the use of millions of particles is required. Specifically, up to 33 and 220 millions of particles were necessary to accurately predict the tephra deposit and Ash Concentration in air, respectively. This is approximately two orders of magnitude larger than the values typically considered running PUFF. The parametric study shows that the horizontal diffusion coefficient, the time step of the simulations, the topography and the standard deviation of the particle distribution greatly affect the model outputs. We also validate the model by best-fit procedures. Results show a good comparison between field data of the 2001 Etna eruption and PUFF simulations, being inside 5 and 1/5 times the observed data, comparable with results of Eulerian models. This work will allow to reliably outline the areas of contaminated airspace using PUFF or any other Lagrangian model in order to define the No Fly Zone and ensure the safety aviation operations as required after the Eyjafjallajokull eruption.
F.s. Marzano - One of the best experts on this subject based on the ideXlab platform.
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TyWRRS - Microwave and optical active remote sensing signatures of volcanic Ash clouds from ground
2012 Tyrrhenian Workshop on Advances in Radar and Remote Sensing (TyWRRS), 2012Co-Authors: F.s. Marzano, Errico Picciotti, Luigi Mereu, Saverio Mori, Mario Montopoli, Giovanni MartucciAbstract:Active remote sensing retrieval from ground, in terms of detection, estimation and sensitivity, of volcanic Ash plumes is not only dependent on the sensors' specifications, but also on the range and Ash cloud distribution. The minimum detectable signal can be increased, for a given system and Ash plume scenario, by decreasing the observation range and increasing the operational frequency using a multi-sensor approach, but also exploiting possible polarimetric capabilities. This work, starting from the results of a previous study and from above mentioned issues, is aimed at quantitatively assessing the optimal choices for microwave and millimeter-wave radar systems with a dual-polarization capability for real-time Ash cloud remote sensing to be used in combination with an optical lidar. The physical-electromagnetic model of Ash particle distributions is systematically reviewed and extended to include non-spherical particle shapes, vesicular composition, silicate content and orientation phenomena. The radar and lidar scattering and absorption response is simulated and analyzed in terms of self-consistent polarimetric signatures for Ash classification purposes and correlation with Ash Concentration and mean diameter for quantitative retrieval aims. A sensitivity analysis to Ash Concentration, as a function of sensor specifications, range and Ash category, is carried out trying to assess the expected multi-sensor multi-spectral system performances and limitations.
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Synthetic Signatures of Volcanic Ash Cloud Particles From X-Band Dual-Polarization Radar
IEEE Transactions on Geoscience and Remote Sensing, 2012Co-Authors: F.s. Marzano, G. Vulpiani, Errico Picciotti, Mario MontopoliAbstract:Weather radar retrieval, in terms of detection, estimation, and sensitivity, of volcanic Ash plumes is dependent not only on the radar system specifications but also on the range and Ash cloud distribution. The minimum detectable signal can be increased, for a given radar and Ash plume scenario, by decreasing the observation range and increasing the operational frequency and also by exploiting possible polarimetric capabilities. For short-range observations in proximity of the volcano vent, a compact portable system with relatively low power transmitter may be evaluated as a suitable compromise between observational and technological requirements. This paper, starting from the results of a previous study and from the aforementioned issues, is aimed at quantitatively assessing the optimal choices for a portable X-band system with a dual-polarization capability for real-time Ash cloud remote sensing. The physical-electromagnetic model of Ash particle distributions is systematically reviewed and extended to include nonspherical particle shapes, vesicular composition, silicate content, and orientation phenomena. The radar backscattering response at X-band is simulated and analyzed in terms of self-consistent polarimetric signatures for Ash classification purposes and correlation with Ash Concentration for quantitative retrieval aims. An X-band radar system sensitivity analysis to Ash Concentration, as a function of radar specifications, range, and Ash category, is carried out in trying to assess the expected system performances and limitations.
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Weather Radar Remote Sensing of Volcanic Ash Clouds for Aviation Hazard and Civil Protection Applications
Integrated Ground-Based Observing Systems, 2010Co-Authors: F.s. MarzanoAbstract:The potential of ground-based microwave weather radar systems for volcanic Ash cloud detection and quantitative retrieval is evaluated. A prototype algorithm for volcanic Ash radar retrieval (VARR) is discussed. Starting from measured single-polarization reflectivity, the statistical inversion technique to retrieve Ash Concentration and fall rate is based on two cascade steps: (i) classification of eruption regime and volcanic Ash category and (ii) estimation of Ash Concentration and fall rate. An application of the VARR technique is finally shown taking into consideration the eruption of the Grimsvotn volcano in Iceland on November 2004. Volume scan data from a Doppler C-band radar, located at 260 km from the volcano vent, are processed by means of the VARR algorithm. Examples of the achievable VARR products are presented and discussed.
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IGARSS - Microwave radar remote sensing of Plinian volcanic Ash clouds for aviation hazard and civil protection applications
2007 IEEE International Geoscience and Remote Sensing Symposium, 2007Co-Authors: F.s. Marzano, S. Barbieri, Errico Picciotti, G. VulpianiAbstract:The potential of ground-based microwave weather radar systems for volcanic Ash cloud detection and quantitative retrieval is evaluated. A prototype algorithm for volcanic Ash radar retrieval (VARR) is discussed. Starting from measured single-polarization reflectivity, the statistical inversion technique to retrieve Ash Concentration and fall rate is based on two cascade steps: i) classification of eruption regime and volcanic Ash category; ii) estimation of Ash Concentration and fall rate. An application of the VARR technique is finally shown taking into consideration the eruption of the Grimsvotn volcano in Iceland on Nov. 2004. Volume scan data from a Doppler C-band radar, located at 260 km from the volcano vent, are processed by means of the VARR algorithm. Examples of the achievable VARR products are presented and discussed.
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Volcanic Ash Cloud Retrieval by Ground-Based Microwave Weather Radar
IEEE Transactions on Geoscience and Remote Sensing, 2006Co-Authors: F.s. Marzano, S. Barbieri, G. Vulpiani, W.i. RoseAbstract:The potential of ground-based microwave weather radar systems for volcanic Ash cloud detection and quantitative retrieval is evaluated. The relationship between radar reflectivity factor, Ash Concentration, and fall rate is statistically derived for various eruption regimes and Ash sizes by applying a radar-reflectivity microphysical model. To quantitatively evaluate the Ash detectability by weather radars, a sensitivity analysis is carried out by simulating synthetic Ash clouds and varying Ash Concentration and size as a function of the range. Radar specifications are taken from typical radar systems at S-, C-, and X-band. A prototype algorithm for volcanic Ash radar retrieval (VARR) is discussed. Starting from measured single-polarization reflectivity, the statistical inversion technique to retrieve Ash Concentration and fall rate is based on two cascade steps, namely: 1) classification of eruption regime and volcanic Ash category and 2) estimation of Ash Concentration and fall rate. Expected accuracy of the VARR algorithm estimates is evaluated using a synthetic data set. An application of the VARR technique is finally shown, taking into consideration the eruption of the Grinodotacutemsvoumltn volcano in Iceland on November 2004. Volume scan data from a Doppler C-band radar, which is located at 260 km from the volcano vent, are processed by means of the VARR algorithm. Examples of the achievable VARR products are presented and discussed
Estela Ángela Collini - One of the best experts on this subject based on the ideXlab platform.
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Volcanic Ash forecast using ensemble-based data assimilation: an ensemble transform Kalman filter coupled with the FALL3D-7.2 model (ETKF–FALL3D version 1.0)
Geoscientific Model Development, 2020Co-Authors: Soledad Osores, Arnau Folch, Juan Ruiz, Estela Ángela ColliniAbstract:Abstract. Quantitative volcanic Ash cloud forecasts are prone to uncertainties coming from the source term quantification (e.g., the eruption strength or vertical distribution of the emitted particles), with consequent implications for an operational Ash impact assessment. We present an ensemble-based data assimilation and forecast system for volcanic Ash dispersal and deposition aimed at reducing uncertainties related to eruption source parameters. The FALL3D atmospheric dispersal model is coupled with the ensemble transform Kalman filter (ETKF) data assimilation technique by combining Ash mass loading observations with Ash dispersal simulations in order to obtain a better joint estimation of the 3-D Ash Concentration and source parameters. The ETKF–FALL3D data assimilation system is evaluated by performing observing system simulation experiments (OSSEs) in which synthetic observations of fine Ash mass loadings are assimilated. The evaluation of the ETKF–FALL3D system, considering reference states of steady and time-varying eruption source parameters, shows that the assimilation process gives both better estimations of Ash Concentration and time-dependent optimized values of eruption source parameters. The joint estimation of Concentrations and source parameters leads to a better analysis and forecast of the 3-D Ash Concentrations. The results show the potential of the methodology to improve volcanic Ash cloud forecasts in operational contexts.
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Volcanic Ash forecast using ensemble-based data assimilation: the Ensemble Transform Kalman Filter coupled with FALL3D-7.2 model (ETKF-FALL3D, version 1.0)
2019Co-Authors: Soledad Osores, Arnau Folch, Juan Ruiz, Estela Ángela ColliniAbstract:Abstract. Quantitative volcanic Ash cloud forecasts are prone to uncertainties coming from the source term quantification (e.g. eruption strength or vertical distribution of the emitted particles), with consequent implications on operational Ash impact assessment. We present an ensemble-based data assimilation and forecast system for volcanic Ash dispersal and deposition aimed at reducing uncertainties related to eruption source parameters. The FALL3D atmospheric dispersal model is coupled with the Ensemble Transform Kalman Filter (ETKF) data assimilation technique by combining Ash mass loading observations with Ash dispersal simulations in order to obtain a better joint estimation of 3D Ash Concentration and source parameters. The ETKF-FALL3D data assimilation system is evaluated performing Observation System Simulation Experiments (OSSE) in which synthetic observations of fine Ash mass loadings are assimilated. The evaluation of the ETKF-FALL3D system considering reference states of steady and time-varying eruption source parameters shows that the assimilation process gives both better estimations of Ash Concentration and time-dependent optimized values of eruption source parameters. The joint estimation of Concentrations and source parameters leads to a better analysis and forecast of the 3D Ash Concentrations. Results show the potential of the methodology to improve volcanic Ash cloud forecasts in operational contexts.
D Parsons - One of the best experts on this subject based on the ideXlab platform.
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urea and composted cattle manure affect forage yield and nutritive value in sandy soils of south central vietnam
Grass and Forage Science, 2018Co-Authors: Keenan C Mcroberts, Quirine M. Ketterings, D Parsons, T T Hai, N H Quan, Charles F Nicholson, Djr CherneyAbstract:Improved forage management can support increased production in smallholder beef systems. Our objective was to evaluate the effects of mineral nitrogen (urea) and composted cattle manure on Brachiaria cv. Mulato II yield and nutritive value in south-central coastal Vietnam. Study design was a randomized complete block on six farms (blocks), with treatments derived from the factorial combination of five rates of composted cattle manure (0, 4, 8, 12 and 24 Mg DM ha -1 year -1 ) and three urea rates (0, 60 and 120 kg N ha -1 year -1 ), split into six yearly applications. Yield was measured from 2011 to 2013 with 36-day average harvest intervals. Forage nutritive value was measured in September 2011 and December 2012. Highest yields were achieved when both compost and urea were applied at high rates. The initial yield and tiller responses to urea application were not sustained over the duration of the study when no compost was applied. Compost applied in isolation did not increase yield. Compost application increased Ash Concentration. Urea increased nutrient yield for all forage nutritive value parameters measured. Composted cattle manure combined with urea benefits grass yield, but high application rates are needed for sustained high yields on sandy soils.
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Urea and composted cattle manure affect forage yield and nutritive value in sandy soils of south‐central Vietnam
Grass and Forage Science, 2017Co-Authors: Keenan C Mcroberts, Quirine M. Ketterings, D Parsons, T T Hai, N H Quan, Charles F Nicholson, Djr CherneyAbstract:Improved forage management can support increased production in smallholder beef systems. Our objective was to evaluate the effects of mineral nitrogen (urea) and composted cattle manure on Brachiaria cv. Mulato II yield and nutritive value in south-central coastal Vietnam. Study design was a randomized complete block on six farms (blocks), with treatments derived from the factorial combination of five rates of composted cattle manure (0, 4, 8, 12 and 24 Mg DM ha -1 year -1 ) and three urea rates (0, 60 and 120 kg N ha -1 year -1 ), split into six yearly applications. Yield was measured from 2011 to 2013 with 36-day average harvest intervals. Forage nutritive value was measured in September 2011 and December 2012. Highest yields were achieved when both compost and urea were applied at high rates. The initial yield and tiller responses to urea application were not sustained over the duration of the study when no compost was applied. Compost applied in isolation did not increase yield. Compost application increased Ash Concentration. Urea increased nutrient yield for all forage nutritive value parameters measured. Composted cattle manure combined with urea benefits grass yield, but high application rates are needed for sustained high yields on sandy soils.
