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G. G. J. Ernst - One of the best experts on this subject based on the ideXlab platform.
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Nature and significance of small volume fall deposits at composite volcanoes: Insights from the October 14, 1974 Fuego eruption, Guatemala
Bulletin of Volcanology, 2008Co-Authors: W. I. Rose, S. Self, P. J. Murrow, C. Bonadonna, A. J. Durant, G. G. J. ErnstAbstract:The first of four successive pulses of the 1974 explosive eruption of Fuego volcano, Guatemala, produced a small volume (∼0.02 km^3 DRE) basaltic sub-plinian tephra fall and flow deposit. Samples collected within 48 h after deposition over much of the dispersal area (7–80 km from the volcano) have been size analyzed down to 8 φ (4 µm). Tephra along the dispersal axis were all well-sorted ( σ _φ = 0.25–1.00), and sorting increased whereas thickness and median grain size decreased systematically downwind. Skewness varied from slightly positive near the vent to slightly negative in distal regions and is consistent with decoupling between coarse ejecta falling off the rising eruption column and fine ash falling off the windblown Volcanic Cloud advecting at the final level of rise. Less dense, vesicular coarse particles form a log normal sub-population when separated from the smaller (Md_φ
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nature and significance of small volume fall deposits at composite volcanoes insights from the october 14 1974 fuego eruption guatemala
Bulletin of Volcanology, 2008Co-Authors: William I. Rose, G. G. J. Ernst, Adam J Durant, P. J. Murrow, C. Bonadonna, Stephen SelfAbstract:The first of four successive pulses of the 1974 explosive eruption of Fuego volcano, Guatemala, produced a small volume (∼0.02 km3 DRE) basaltic sub-plinian tephra fall and flow deposit. Samples collected within 48 h after deposition over much of the dispersal area (7–80 km from the volcano) have been size analyzed down to 8 φ (4 µm). Tephra along the dispersal axis were all well-sorted (σ φ = 0.25–1.00), and sorting increased whereas thickness and median grain size decreased systematically downwind. Skewness varied from slightly positive near the vent to slightly negative in distal regions and is consistent with decoupling between coarse ejecta falling off the rising eruption column and fine ash falling off the windblown Volcanic Cloud advecting at the final level of rise. Less dense, vesicular coarse particles form a log normal sub-population when separated from the smaller (Mdφ < 3φ or < 0.125 mm), denser shard and crystal sub-population. A unimodal, relatively coarse (Mdφ = 0.58φ or 0.7 mm σ φ = 1.2) initial grain size population is estimated for the whole (fall and flow) deposit. Only a small part of the fine-grained, thin 1974 Fuego tephra deposit has survived erosion to the present day. The initial October 14 pulse, with an estimated column height of 15 km above sea level, was a primary cause of a detectable perturbation in the northern hemisphere stratospheric aerosol layer in late 1974 to early 1975. Such small, sulfur-rich, explosive eruptions may substantially contribute to the overall stratospheric sulfur budget, yet leave only transient deposits, which have little chance of survival even in the recent geologic record. The fraction of finest particles (Mdφ = 4–8φ or 4–63 µm) in the Fuego tephra makes up a separate but minor size mode in the size distribution of samples around the margin of the deposit. A previously undocumented bimodal–unimodal–bimodal change in grain size distribution across the dispersal axis at 20 km downwind from the vent is best accounted for as the result of fallout dispersal of ash from a higher subplinian column and a lower “co-pf” Cloud resulting from pyroclastic flows. In addition, there is a degree of asymmetry in the documented grain-size fallout pattern which is attributed to vertically veering wind direction and changing windspeeds, especially across the tropopause. The distribution of fine particles (<8 µm diameter) in the tephra deposit is asymmetrical, mainly along the N edge, with a small enrichment along the S edge. This pattern has hazard significance.
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Weather radar observations of the Hekla 2000 eruption Cloud, Iceland
Bulletin of Volcanology, 2004Co-Authors: Claude Lacasse, Heidi Soosalu, W. I. Rose, SigrÙn Karlsdottir, G Larsen, G. G. J. ErnstAbstract:The Hekla eruption Cloud on 26–27 February 2000 was the first Volcanic Cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflavík international airport. Real-time radar observations of the onset, advection, and waning of the eruption Cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire Volcanic Cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The Cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of ~30 to 50 m s^−1, before it reached an altitude of ~11–12 km. The evolution of the reflected Cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded Volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30–45 dBz portions of the reflected Cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption Cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and Volcanic Cloud radar map are due to the fact that the greater part of the deposit originates by fallout off the column margins and from the base of the Cloud followed by advection of falling particle in lower level winds.
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Weather radar observations of the Hekla 2000 eruption Cloud, Iceland
Bulletin of Volcanology, 2004Co-Authors: Claude Lacasse, Heidi Soosalu, W. I. Rose, G Larsen, S Karlsdottir, G. G. J. ErnstAbstract:The Hekla eruption Cloud on 26–27 February 2000 was the first Volcanic Cloud to be continuously and completely monitored advecting above Iceland, using the C-band weather radar near the Keflavík international airport. Real-time radar observations of the onset, advection, and waning of the eruption Cloud were studied using time series of PPI (plan-position indicator) radar images, including VMI normal, Echotop, and Cappi level 2 displays. The reflectivity of the entire Volcanic Cloud ranges from 0 to >60 dBz. The eruption column above the vent is essentially characterised by VMI normal and Cappi level 2 values, >30 dBz, due to the dominant influence of lapilli and ash (tephra) on the overall reflected signal. The Cloud generated by the column was advected downwind to the north-northeast. It is characterised by values between 0 and 30 dBz, and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles. Echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of ~30 to 50 m s^−1, before it reached an altitude of ~11–12 km. The evolution of the reflected Cloud was studied from the area change in pixels of its highly reflected portions, >30 dBz, and tied to recorded Volcanic tremor amplitudes. The synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18:20 to 19:00 UTC on 26 February. From 19:00 the >45 dBz and 30–45 dBz portions of the reflected Cloud decrease and disappear at about 7 and 10.5 h, respectively, after the eruption began, indicating the end of the decaying explosive phase. The advection and extent of the reflected eruption Cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h. Differences in the deposit map and Volcanic Cloud radar map are due to the fact that the greater part of the deposit originates by fallout off the column margins and from the base of the Cloud followed by advection of falling particle in lower level winds.
William I. Rose - One of the best experts on this subject based on the ideXlab platform.
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el chichon volcano april 4 1982 Volcanic Cloud history and fine ash fallout
Natural Hazards, 2009Co-Authors: William I. Rose, Adam J DurantAbstract:This retrospective study focuses on the fine silicate particles (>62 µm in diameter) produced in a large eruption that was otherwise well studied. Fine particles represent a potential hazard to aircraft, because as simple particles they have very low terminal velocities and could potentially stay aloft for weeks. New data were collected to describe the fine particle size distributions of distal fallout samples collected soon after eruption. Although, about half of the mass of silicate particles produced in this eruption of ~1 km 3 dense rock equivalent magma were finer than 62 µm in diameter, and although these particles were in a stratospheric Cloud after eruption, almost all of these fine particles fell to the ground near (>300 km) the volcano in a day or two. Particles falling out from 70 to 300 km from the volcano are mostly >62 µm in diameter. The most plausible explanation for rapid fallout is that the fine ash nucleates ice in the convective Cloud and initiates a process of meteorological precipitation that efficiently removes fine silicates. These observations are similar to other eruptions and we conclude that ice formation in convective Volcanic Clouds is part of an effective fine ash removal process that affects all or most Volcanic Clouds. The existence of pyroclastic flows and surges in the El Chichon eruption increased the overall proportion of fine silicates, probably by milling larger glassy pyroclasts. Copyright Springer Science+Business Media B.V. 2009
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sedimentological constraints on hydrometeor enhanced particle deposition 1992 eruptions of crater peak alaska
Journal of Volcanology and Geothermal Research, 2009Co-Authors: Adam J Durant, William I. RoseAbstract:Abstract Water is a dominant component of Volcanic Clouds and has fundamental control on very fine particle deposition. Particle size characteristics of distal tephra-fall (100s km from source volcano) have a higher proportion of very fine particles compared to predictions based on single particle settling rates. In this study, sedimentological analyses of fallout from for the 18 August and 16–17 September 1992 eruptions of Crater Peak, Alaska, are combined with satellite observations, and Cloud trajectory and microphysics modeling to investigate meteorological influences on particle sedimentation. Total grain size distributions of tephra fallout were reconstructed for both Crater Peak eruptions and indicate a predominance of fine particles − 2 g m − 3 (based on an estimated Cloud thickness of ~ 1000 m from trajectory modeling). Hydrometeor formation on particles in the Volcanic Cloud and subsequent sublimation may induce a Cloud base instability that leads to rapid bulk ( en masse ) sedimentation of very fine particles through a mammatus-like mechanism.
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hydrometeor enhanced tephra sedimentation constraints from the 18 may 1980 eruption of mount st helens
Journal of Geophysical Research, 2009Co-Authors: William I. Rose, Adam J Durant, Andrei M Sarnawojcicki, Steven Carey, A C M VolentikAbstract:[1] Uncertainty remains on the origin of distal mass deposition maxima observed in many recent tephra fall deposits. In this study the link between ash aggregation and the formation of distal mass deposition maxima is investigated through reanalysis of tephra fallout from the Mount St. Helens 18 May 1980 (MSH80) eruption. In addition, we collate all the data needed to model distal ash sedimentation from the MSH80 eruption Cloud. Four particle size subpopulations were present in distal fallout with modes at 2.2 Φ, 4.2 Φ, 5.9 Φ, and 8.3 Φ. Settling rates of the coarsest subpopulation closely matched predicted single-particle terminal fall velocities. Sedimentation of particles <100 μm was greatly enhanced, predominantly through aggregation of a particle subpopulation with modal diameter 5.9 ± 0.2 Φ (19 ± 3 μm). Mammatus on the MSH80 Cloud provided a mechanism to transport very fine ash particles, with predicted atmospheric lifetimes of days to weeks, from the upper troposphere to the surface in a matter of hours. In this mechanism, ash particles initiate ice hydrometeor formation high in the troposphere. Subsequently, the Volcanic Cloud rapidly subsides as mammatus develop from increased particle loading and Cloud base sublimation. Rapid fallout occurs as the Cloud passes through the melting level in a process analogous to snowflake aggregation. Aggregates sediment en masse and form the distal mass deposition maxima observed in many recent Volcanic ash fall deposits. This work provides a data resource that will facilitate tephra sedimentation modeling and allow model intercomparisons.
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nature and significance of small volume fall deposits at composite volcanoes insights from the october 14 1974 fuego eruption guatemala
Bulletin of Volcanology, 2008Co-Authors: William I. Rose, G. G. J. Ernst, Adam J Durant, P. J. Murrow, C. Bonadonna, Stephen SelfAbstract:The first of four successive pulses of the 1974 explosive eruption of Fuego volcano, Guatemala, produced a small volume (∼0.02 km3 DRE) basaltic sub-plinian tephra fall and flow deposit. Samples collected within 48 h after deposition over much of the dispersal area (7–80 km from the volcano) have been size analyzed down to 8 φ (4 µm). Tephra along the dispersal axis were all well-sorted (σ φ = 0.25–1.00), and sorting increased whereas thickness and median grain size decreased systematically downwind. Skewness varied from slightly positive near the vent to slightly negative in distal regions and is consistent with decoupling between coarse ejecta falling off the rising eruption column and fine ash falling off the windblown Volcanic Cloud advecting at the final level of rise. Less dense, vesicular coarse particles form a log normal sub-population when separated from the smaller (Mdφ < 3φ or < 0.125 mm), denser shard and crystal sub-population. A unimodal, relatively coarse (Mdφ = 0.58φ or 0.7 mm σ φ = 1.2) initial grain size population is estimated for the whole (fall and flow) deposit. Only a small part of the fine-grained, thin 1974 Fuego tephra deposit has survived erosion to the present day. The initial October 14 pulse, with an estimated column height of 15 km above sea level, was a primary cause of a detectable perturbation in the northern hemisphere stratospheric aerosol layer in late 1974 to early 1975. Such small, sulfur-rich, explosive eruptions may substantially contribute to the overall stratospheric sulfur budget, yet leave only transient deposits, which have little chance of survival even in the recent geologic record. The fraction of finest particles (Mdφ = 4–8φ or 4–63 µm) in the Fuego tephra makes up a separate but minor size mode in the size distribution of samples around the margin of the deposit. A previously undocumented bimodal–unimodal–bimodal change in grain size distribution across the dispersal axis at 20 km downwind from the vent is best accounted for as the result of fallout dispersal of ash from a higher subplinian column and a lower “co-pf” Cloud resulting from pyroclastic flows. In addition, there is a degree of asymmetry in the documented grain-size fallout pattern which is attributed to vertically veering wind direction and changing windspeeds, especially across the tropopause. The distribution of fine particles (<8 µm diameter) in the tephra deposit is asymmetrical, mainly along the N edge, with a small enrichment along the S edge. This pattern has hazard significance.
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atmospheric chemistry of a 33 34 hour old Volcanic Cloud from hekla volcano iceland insights from direct sampling and the application of chemical box modeling
Journal of Geophysical Research, 2006Co-Authors: William I. Rose, D E Hunton, B E Anderson, G A Millard, Tamsin A Mather, Clive Oppenheimer, Brett F Thornton, Terrence M Gerlach, Albert A ViggianoAbstract:[1] On 28 February 2000, a Volcanic Cloud from Hekla volcano, Iceland, was serendipitously sampled by a DC-8 research aircraft during the SAGE III Ozone Loss and Validation Experiment (SOLVE I). It was encountered at night at 10.4 km above sea level (in the lower stratosphere) and 33–34 hours after emission. The Cloud is readily identified by abundant SO2 (≤1 ppmv), HCl (≤70 ppbv), HF (≤60 ppbv), and particles (which may have included fine silicate ash). We compare observed and modeled Cloud compositions to understand its chemical evolution. Abundances of sulfur and halogen species indicate some oxidation of sulfur gases but limited scavenging and removal of halides. Chemical modeling suggests that Cloud concentrations of water vapor and nitric acid promoted polar stratospheric Cloud (PSC) formation at 201–203 K, yielding ice, nitric acid trihydrate (NAT), sulfuric acid tetrahydrate (SAT), and liquid ternary solution H2SO4/H2O/HNO3 (STS) particles. We show that these Volcanically induced PSCs, especially the ice and NAT particles, activated volcanogenic halogens in the Cloud producing >2 ppbv ClOx. This would have destroyed ozone during an earlier period of daylight, consistent with the very low levels of ozone observed. This combination of volcanogenic PSCs and chlorine destroyed ozone at much faster rates than other PSCs that Arctic winter. Elevated levels of HNO3 and NOy in the Cloud can be explained by atmospheric nitrogen fixation in the eruption column due to high temperatures and/or Volcanic lightning. However, observed elevated levels of HOx remain unexplained given that the Cloud was sampled at night.
Stefano Corradini - One of the best experts on this subject based on the ideXlab platform.
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Volcanic Cloud Top Height Estimation Using the Plume Elevation Model Procedure Applied to Orthorectified Landsat 8 Data. Test Case: 26 October 2013 Mt. Etna Eruption
Remote Sensing, 2019Co-Authors: Marcello De Michele, Stefano Corradini, Luca Merucci, Daniel Raucoules, Giuseppe Salerno, Pasquale Sellitto, Elisa CarboniAbstract:In this study, we present a method for extracting the Volcanic Cloud top height (VCTH) as a plume elevation model (PEM) from orthorectified Landsat 8 data (Level 1). A similar methodology was previously applied to raw Landsat-8 data (Level 0). But level 0 data are not the standard product provided by the National Aeronautics and Space Administration (NASA)/United States Geological Survey (USGS). Level 0 data are available only on demand and consist on 14 data stripes multiplied by the number of multispectral bands. The standard product for Landsat 8 is the ortho image, available free of charge for end-users. Therefore, there is the need to adapt our previous methodology to Level 1 Landsat data. The advantages of using the standard Landsat products instead of raw data mainly include the fast -ready to use- availability of the data and free access to registered users, which is of major importance during Volcanic crises. In this study, we adapt the PEM methodology to the standard Landsat-8 products, with the aim of simplifying the procedure for routine monitoring, offering an opportunity to produce PEM maps. In this study, we present the method. Our approach is applied to the 26 October 2013 Mt. Etna episodes comparing results independent VCTH measures from the spinning enhanced visible and infrared imager (SEVIRI) and the moderate resolution imaging spectroradiometer (MODIS).
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proximal monitoring of the 2011 2015 etna lava fountains using msg seviri data
Geosciences, 2018Co-Authors: Stefano Corradini, Lorenzo Guerrieri, Luca Merucci, Simona Scollo, Valerio Lombardo, Massimo Musacchio, Michele Prestifilippo, Malvina Silvestri, G Spata, Dario StelitanoAbstract:From 2011 to 2015, 49 lava fountains occurred at Etna volcano. In this work, the measurements carried out from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instrument, on board the Meteosat Second Generation (MSG) geostationary satellite, are processed to realize a proximal monitoring of the eruptive activity for each event. The SEVIRI measurements are managed to provide the time series of start and duration of eruption and fountains, Time Averaged Discharge Rate (TADR) and Volcanic Plume Top Height (VPTH). Due to its temperature responsivity, the eruptions start and duration, fountains start and duration and TADR are realized by exploiting the SEVIRI 3.9 μm channel, while the VPTH is carried out by applying a simplified procedure based on the SEVIRI 10.8 μm brightness temperature computation. For each event, the start, duration and TADR have been compared with ground-based observations. The VPTH time series is compared with the results obtained from a procedures-based on the Volcanic Cloud center of mass tracking in combination with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectories. The results indicate that SEVIRI is generally able to detect the start of the lava emission few hours before the ground measurements. A good agreement is found for both the start and the duration of the fountains and the VPTH with mean differences of about 1 h, 50 min and 1 km respectively.
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multisatellite multisensor observations of a sub plinian Volcanic eruption the 2015 calbuco explosive event in chile
IEEE Transactions on Geoscience and Remote Sensing, 2018Co-Authors: F S Marzano, Stefano Corradini, Luca Merucci, Mario Montopoli, Luigi Mereu, Arve Kylling, D Cimini, Dario StelitanoAbstract:A-train satellite data, acquired during the Calbuco volcano (Chile) sub-Plinian eruption in April 2015, are discussed to explore the complementarity of spaceborne observations in the microwave (MW), thermal infrared (TIR), and visible wavelengths for both near-source plume and distal ash Clouds. The analysis shows that TIR-based detection techniques are not suitable near the Volcanic vent where rising convective columns are associated with large optical depths. Detection and parametric estimates of near-source tephra mass loading and plume height from MW radiometric data, available 69 min after the eruption onset, are proposed. Results indicate a maximum plume altitude of about 21 km above the sea level and an ash mass of $3.65 \times 10^{10}$ kg, in agreement with mass values obtained from empirical formulas, but less than proximal–distal mass deposit of $1.86 \times 10^{11}$ kg. This discrepancy may be explained by extrapolating Advanced Technology Microwave Sounder-based estimates to 6 h, thus obtaining a total mass of about $1.90 \times 10^{11}$ kg. Distal Volcanic Cloud retrievals are derived from TIR imagery and results show a good agreement between Moderate-Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) retrievals of total mass taking into account the overpass time shift. If only the overlapping pixels between MODIS and VIIRS are considered, the respective estimates are $1.90 \times 10^{9}$ kg and $1.80 \times 10^{9}$ kg. TIR radiometric estimates of distal ash Cloud height and mass loadings are also compared with Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations lidar retrievals. For low-to-medium optically thick ash Cloud, average Cloud-Aerosol Lidar with Orthogonal Polarization-derived mass loading is about 0.8 g/m2 against 0.4 g/m2 from VIIRS and 1.4 g/m2 from MODIS.
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The Use of High-Resolution Pléiades Images to Extract Volcanic-Cloud Top Heights and Plume Elevation Models: examples on Mount Etna (Italy) and Mount Ontake (Japan)
2017Co-Authors: Marcello De Michele, Stefano Corradini, Daniel Raucoules, Luca MerucciAbstract:Accurate and spatially-detailed knowledge of Volcanic Cloud Top Height (VCTH) and velocity is crucial in vol-canology. As an example, the ash/gas dispersion in the atmosphere, their impact and lifetime around the globe, greatly depends on the injection altitude. The VCTH is critical for ash dispersion modelling and air traffic security. Furthermore, the Volcanic plume height during explosive volcanism is the primary parameter for estimating mass eruption rate. Satellite remote sensing offers a comprehensive and safe way to estimate VCTH. Recently, it has been shown that high spatial resolution optical imagery from Landsat-8 OLI sensor can be used to extract Volcanic Cloud Top Height with a precision of 250 meters and an accuracy or ∼300m (de Michele et al., 2016). This method allows to extract a Plume Elevation Model (PEM) by jointly measuring the parallax between two optical bands acquired with a time lag varying from 0.1 to 2.5 seconds depending on the bands chosen and the sensors employed. The measure of the parallax is biased because the Volcanic Cloud is moving between the two images acquisitions, even if the time lag is short. The precision of our measurements is enhanced by compensating the parallax by measuring the velocity of the Volcanic Cloud in the perpendicular-to-epipolar direction (which is height independent) and correcting the initial parallax measurement. In this study, we push this methodology forward. We apply it to the very high spatial resolution Pleiades data (1m pixel spacing) provided by the French Space Agency (CNES). We apply the method on Mount Etna, during the 05 September 2015 eruptive episode and on Mount On-take eruption occurring on 30 September 2014. We are able to extract VCTH as a PEM with high spatial resolution and improved precision. Since Pléiades has an improved revisit time (1day), our method has potential for routine monitoring of Volcanic plumes in clear sky conditions and when the VCTH is higher than meteo Clouds.
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real time retrieval of Volcanic Cloud particles and so 2 by satelliteusing an improved simplified approach
Atmospheric Measurement Techniques, 2016Co-Authors: Sergio Pugnaghi, Lorenzo Guerrieri, Stefano Corradini, Luca MerucciAbstract:Abstract. Volcanic plume removal (VPR) is a procedure developed to retrieve the ash optical depth, effective radius and mass, and sulfur dioxide mass contained in a Volcanic Cloud from the thermal radiance at 8.7, 11, and 12 µm. It is based on an estimation of a virtual image representing what the sensor would have seen in a multispectral thermal image if the Volcanic Cloud were not present. Ash and sulfur dioxide were retrieved by the first version of the VPR using a very simple atmospheric model that ignored the layer above the Volcanic Cloud. This new version takes into account the layer of atmosphere above the Cloud as well as thermal radiance scattering along the line of sight of the sensor. In addition to improved results, the new version also offers an easier and faster preliminary preparation and includes other types of Volcanic particles (andesite, obsidian, pumice, ice crystals, and water droplets). As in the previous version, a set of parameters regarding the Volcanic area, particle types, and sensor is required to run the procedure. However, in the new version, only the mean plume temperature is required as input data. In this work, a set of parameters to compute the Volcanic Cloud transmittance in the three quoted bands, for all the aforementioned particles, for both Mt. Etna (Italy) and Eyjafjallajokull (Iceland) volcanoes, and for the Terra and Aqua MODIS instruments is presented. Three types of tests are carried out to verify the results of the improved VPR. The first uses all the radiative transfer simulations performed to estimate the above mentioned parameters. The second one makes use of two synthetic images, one for Mt. Etna and one for Eyjafjallajokull volcanoes. The third one compares VPR and Look-Up Table (LUT) retrievals analyzing the true image of Eyjafjallajokull volcano acquired by MODIS aboard the Aqua satellite on 11 May 2010 at 14:05 GMT.
Luca Merucci - One of the best experts on this subject based on the ideXlab platform.
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Volcanic Cloud Top Height Estimation Using the Plume Elevation Model Procedure Applied to Orthorectified Landsat 8 Data. Test Case: 26 October 2013 Mt. Etna Eruption
Remote Sensing, 2019Co-Authors: Marcello De Michele, Stefano Corradini, Luca Merucci, Daniel Raucoules, Giuseppe Salerno, Pasquale Sellitto, Elisa CarboniAbstract:In this study, we present a method for extracting the Volcanic Cloud top height (VCTH) as a plume elevation model (PEM) from orthorectified Landsat 8 data (Level 1). A similar methodology was previously applied to raw Landsat-8 data (Level 0). But level 0 data are not the standard product provided by the National Aeronautics and Space Administration (NASA)/United States Geological Survey (USGS). Level 0 data are available only on demand and consist on 14 data stripes multiplied by the number of multispectral bands. The standard product for Landsat 8 is the ortho image, available free of charge for end-users. Therefore, there is the need to adapt our previous methodology to Level 1 Landsat data. The advantages of using the standard Landsat products instead of raw data mainly include the fast -ready to use- availability of the data and free access to registered users, which is of major importance during Volcanic crises. In this study, we adapt the PEM methodology to the standard Landsat-8 products, with the aim of simplifying the procedure for routine monitoring, offering an opportunity to produce PEM maps. In this study, we present the method. Our approach is applied to the 26 October 2013 Mt. Etna episodes comparing results independent VCTH measures from the spinning enhanced visible and infrared imager (SEVIRI) and the moderate resolution imaging spectroradiometer (MODIS).
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proximal monitoring of the 2011 2015 etna lava fountains using msg seviri data
Geosciences, 2018Co-Authors: Stefano Corradini, Lorenzo Guerrieri, Luca Merucci, Simona Scollo, Valerio Lombardo, Massimo Musacchio, Michele Prestifilippo, Malvina Silvestri, G Spata, Dario StelitanoAbstract:From 2011 to 2015, 49 lava fountains occurred at Etna volcano. In this work, the measurements carried out from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instrument, on board the Meteosat Second Generation (MSG) geostationary satellite, are processed to realize a proximal monitoring of the eruptive activity for each event. The SEVIRI measurements are managed to provide the time series of start and duration of eruption and fountains, Time Averaged Discharge Rate (TADR) and Volcanic Plume Top Height (VPTH). Due to its temperature responsivity, the eruptions start and duration, fountains start and duration and TADR are realized by exploiting the SEVIRI 3.9 μm channel, while the VPTH is carried out by applying a simplified procedure based on the SEVIRI 10.8 μm brightness temperature computation. For each event, the start, duration and TADR have been compared with ground-based observations. The VPTH time series is compared with the results obtained from a procedures-based on the Volcanic Cloud center of mass tracking in combination with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back-trajectories. The results indicate that SEVIRI is generally able to detect the start of the lava emission few hours before the ground measurements. A good agreement is found for both the start and the duration of the fountains and the VPTH with mean differences of about 1 h, 50 min and 1 km respectively.
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multisatellite multisensor observations of a sub plinian Volcanic eruption the 2015 calbuco explosive event in chile
IEEE Transactions on Geoscience and Remote Sensing, 2018Co-Authors: F S Marzano, Stefano Corradini, Luca Merucci, Mario Montopoli, Luigi Mereu, Arve Kylling, D Cimini, Dario StelitanoAbstract:A-train satellite data, acquired during the Calbuco volcano (Chile) sub-Plinian eruption in April 2015, are discussed to explore the complementarity of spaceborne observations in the microwave (MW), thermal infrared (TIR), and visible wavelengths for both near-source plume and distal ash Clouds. The analysis shows that TIR-based detection techniques are not suitable near the Volcanic vent where rising convective columns are associated with large optical depths. Detection and parametric estimates of near-source tephra mass loading and plume height from MW radiometric data, available 69 min after the eruption onset, are proposed. Results indicate a maximum plume altitude of about 21 km above the sea level and an ash mass of $3.65 \times 10^{10}$ kg, in agreement with mass values obtained from empirical formulas, but less than proximal–distal mass deposit of $1.86 \times 10^{11}$ kg. This discrepancy may be explained by extrapolating Advanced Technology Microwave Sounder-based estimates to 6 h, thus obtaining a total mass of about $1.90 \times 10^{11}$ kg. Distal Volcanic Cloud retrievals are derived from TIR imagery and results show a good agreement between Moderate-Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) retrievals of total mass taking into account the overpass time shift. If only the overlapping pixels between MODIS and VIIRS are considered, the respective estimates are $1.90 \times 10^{9}$ kg and $1.80 \times 10^{9}$ kg. TIR radiometric estimates of distal ash Cloud height and mass loadings are also compared with Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations lidar retrievals. For low-to-medium optically thick ash Cloud, average Cloud-Aerosol Lidar with Orthogonal Polarization-derived mass loading is about 0.8 g/m2 against 0.4 g/m2 from VIIRS and 1.4 g/m2 from MODIS.
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The Use of High-Resolution Pléiades Images to Extract Volcanic-Cloud Top Heights and Plume Elevation Models: examples on Mount Etna (Italy) and Mount Ontake (Japan)
2017Co-Authors: Marcello De Michele, Stefano Corradini, Daniel Raucoules, Luca MerucciAbstract:Accurate and spatially-detailed knowledge of Volcanic Cloud Top Height (VCTH) and velocity is crucial in vol-canology. As an example, the ash/gas dispersion in the atmosphere, their impact and lifetime around the globe, greatly depends on the injection altitude. The VCTH is critical for ash dispersion modelling and air traffic security. Furthermore, the Volcanic plume height during explosive volcanism is the primary parameter for estimating mass eruption rate. Satellite remote sensing offers a comprehensive and safe way to estimate VCTH. Recently, it has been shown that high spatial resolution optical imagery from Landsat-8 OLI sensor can be used to extract Volcanic Cloud Top Height with a precision of 250 meters and an accuracy or ∼300m (de Michele et al., 2016). This method allows to extract a Plume Elevation Model (PEM) by jointly measuring the parallax between two optical bands acquired with a time lag varying from 0.1 to 2.5 seconds depending on the bands chosen and the sensors employed. The measure of the parallax is biased because the Volcanic Cloud is moving between the two images acquisitions, even if the time lag is short. The precision of our measurements is enhanced by compensating the parallax by measuring the velocity of the Volcanic Cloud in the perpendicular-to-epipolar direction (which is height independent) and correcting the initial parallax measurement. In this study, we push this methodology forward. We apply it to the very high spatial resolution Pleiades data (1m pixel spacing) provided by the French Space Agency (CNES). We apply the method on Mount Etna, during the 05 September 2015 eruptive episode and on Mount On-take eruption occurring on 30 September 2014. We are able to extract VCTH as a PEM with high spatial resolution and improved precision. Since Pléiades has an improved revisit time (1day), our method has potential for routine monitoring of Volcanic plumes in clear sky conditions and when the VCTH is higher than meteo Clouds.
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real time retrieval of Volcanic Cloud particles and so 2 by satelliteusing an improved simplified approach
Atmospheric Measurement Techniques, 2016Co-Authors: Sergio Pugnaghi, Lorenzo Guerrieri, Stefano Corradini, Luca MerucciAbstract:Abstract. Volcanic plume removal (VPR) is a procedure developed to retrieve the ash optical depth, effective radius and mass, and sulfur dioxide mass contained in a Volcanic Cloud from the thermal radiance at 8.7, 11, and 12 µm. It is based on an estimation of a virtual image representing what the sensor would have seen in a multispectral thermal image if the Volcanic Cloud were not present. Ash and sulfur dioxide were retrieved by the first version of the VPR using a very simple atmospheric model that ignored the layer above the Volcanic Cloud. This new version takes into account the layer of atmosphere above the Cloud as well as thermal radiance scattering along the line of sight of the sensor. In addition to improved results, the new version also offers an easier and faster preliminary preparation and includes other types of Volcanic particles (andesite, obsidian, pumice, ice crystals, and water droplets). As in the previous version, a set of parameters regarding the Volcanic area, particle types, and sensor is required to run the procedure. However, in the new version, only the mean plume temperature is required as input data. In this work, a set of parameters to compute the Volcanic Cloud transmittance in the three quoted bands, for all the aforementioned particles, for both Mt. Etna (Italy) and Eyjafjallajokull (Iceland) volcanoes, and for the Terra and Aqua MODIS instruments is presented. Three types of tests are carried out to verify the results of the improved VPR. The first uses all the radiative transfer simulations performed to estimate the above mentioned parameters. The second one makes use of two synthetic images, one for Mt. Etna and one for Eyjafjallajokull volcanoes. The third one compares VPR and Look-Up Table (LUT) retrievals analyzing the true image of Eyjafjallajokull volcano acquired by MODIS aboard the Aqua satellite on 11 May 2010 at 14:05 GMT.
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sulphur dioxide as a Volcanic ash proxy during the april may 2010 eruption of eyjafjallajokull volcano iceland
Atmospheric Chemistry and Physics, 2011Co-Authors: Helen Thomas, A J PrataAbstract:Abstract. The Volcanic ash Cloud from the eruption of Eyjafjallajokull volcano in April and May 2010 resulted in unprecedented disruption to air traffic in Western Europe causing significant financial losses and highlighting the importance of efficient Volcanic Cloud monitoring. The feasibility of using SO 2 as a tracer for the ash released during the eruption is investigated here through comparison of ash retrievals from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) with SO 2 measurements from a number of infrared and ultraviolet satellite-based sensors. Results demonstrate that the eruption can be divided into an initial ash-rich phase, a lower intensity middle phase and a final phase where considerably greater quantities both ash and SO 2 were released. Comparisons of ash-SO 2 dispersion indicate that despite frequent collocation of the two species, there are a number of instances throughout the eruption where separation is observed. This separation occurs vertically due to the more rapid settling rate of ash compared to SO 2 , horizontally through wind shear and temporally through volcanological controls on eruption style. The potential for the two species to be dispersed independently has consequences in terms of aircraft hazard mitigation and highlights the importance of monitoring both species concurrently.
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Volcanic ash and so2 in the 2008 kasatochi eruption retrievals comparison from different ir satellite sensors
Journal of Geophysical Research, 2010Co-Authors: Stefano Corradini, Luca Merucci, A J Prata, Alessandro PisciniAbstract:[1] The Kasatochi 2008 eruption was detected by several infrared satellite sensors including Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High Resolution Radiometer (AVHRR), and Atmospheric Infrared Sounder (AIRS). In this work a comparison between the Volcanic Cloud SO2 and ash retrievals derived from these instruments has been undertaken. The SO2 retrieval is carried out by using both the 7.3 and 8.7 μm absorption features while ash retrieval exploits the 10–12 μm atmospheric window. A radiative transfer scheme is also used to correct the Volcanic ash effect on the 8.7 μm SO2 signature. As test cases, three near-contemporary images for each sensor, collected during the first days of the eruption, have been analyzed. The results show that the Volcanic SO2 and ash are simultaneously present and generally collocated. The MODIS and AVHRR total ash mass loadings are in good agreement and estimated to be about 0.5 Tg, while the AIRS retrievals are slightly lower and equal to about 0.3 Tg. The AIRS and MODIS 7.3 μm SO2 mass loadings are also in good agreement and vary between 0.3 and 1.2 Tg, while the MODIS ash corrected 8.7 μm SO2 masses vary between 0.4 and 2.7 Tg. The mass increase with time confirms the continuous SO2 injection in the atmosphere after the main explosive episodes. Moreover the difference between the 7.3 and 8.7 μm retrievals suggests a vertical stratification of the Volcanic Cloud. The results also confirm the importance of the ash correction; the corrected 8.7 μm SO2 total masses are less than 30–40% of the uncorrected values.
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Satellite detection of hazardous Volcanic Clouds and the risk to global air traffic
Natural Hazards, 2009Co-Authors: A J PrataAbstract:Remote sensing instruments have been used to identify, track and in some cases quantify atmospheric constituents from space-borne platforms for nearly 30 years. These data have proven to be extremely useful for detecting hazardous ash and gas (principally SO_2) Clouds emitted by volcanoes and which have the potential to intersect global air routes. The remoteness of volcanoes, the sporadic timings of eruptions and the ability of the upper atmosphere winds to quickly spread ash and gas, make satellite remote sensing a key tool for developing hazard warning systems. It is easily recognized how powerful these tools are for hazard detection and yet there has not been a single instrument designed specifically for this use. Instead, researchers have had to make use of instruments and data designed for other purposes. In this article the satellite instruments, algorithms and techniques used for ash and gas detection are described from a historical perspective with a view to elucidating their value and shortcomings. Volcanic Clouds residing in the mid- to upper-troposphere (heights above 5 km) have the greatest potential of intersecting air routes and can be dispersed over many 1,000s of kilometres by the prevailing winds. Global air traffic vulnerability to the threat posed by Volcanic Clouds is then considered from the perspectives of satellite remote sensing, the upper troposphere mean wind circulation, and current and forecast air traffic density based on an up-to-date aircraft emissions inventory. It is concluded that aviation in the Asia Pacific region will be increasingly vulnerable to Volcanic Cloud encounters because of the large number of active volcanoes in the region and the increasing growth rate of air traffic in that region. It is also noted that should high-speed civil transport (HSCT) aircraft become operational, there will be an increased risk to Volcanic debris that is far from its source location. This vulnerability is highlighted using air traffic density maps based on NOx emissions and satellite SO_2 observations of the spread of Volcanic Clouds.
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circumpolar transport of a Volcanic Cloud from hekla iceland
Journal of Geophysical Research, 2008Co-Authors: S A Carn, A J Prata, S KarlsdottirAbstract:[1] Hekla volcano (Iceland) erupted on 17 August 1980 and emplaced a sulfur dioxide (SO2) Cloud into the north polar stratosphere at a maximum altitude of ∼15 km. The SO2 is tracked using satellite data from the ultraviolet (UV) Nimbus-7 Total Ozone Mapping Spectrometer (N7/TOMS) and the infrared (IR) High-resolution Infrared Radiation Sounder (HIRS/2) on the NOAA TIROS Operational Vertical Sounder (TOVS) platform. The eruption emitted ∼0.5–0.7 Tg of SO2, which later split into three distinct Clouds, one of which circled the North Pole at the perimeter of an atypically persistent Arctic cyclone for six days, impacting airspace on three continents. Separate Clouds drifted across eastern Russia, Alaska, and Canada. Maximum SO2 columns derived from TOMS and HIRS/2 accurately define the Volcanic Cloud's path and fit trajectories produced by the NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, providing confidence in the model. When combined with the SO2 measurements, trajectory altitudes derived from HYSPLIT provide robust estimates of the altitudes of the SO2 Clouds (8–15 km), which would be elusive using either the satellite data or the trajectory model in isolation. Near-coincident, spectrally discrete UV and IR retrievals are compared in the Volcanic Cloud and indicate good agreement between TOMS and HIRS/2 SO2 columns for pixels with similar viewing geometry. Hekla eruptions, which follow a pattern of early explosive venting of Volcanic gases with significant stratospheric injection, could play a role in promoting Arctic ozone loss, depending on the phase of the North Atlantic Oscillation during the eruption.
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long range transport and fate of a stratospheric Volcanic Cloud from soufriere hills volcano montserrat
Atmospheric Chemistry and Physics, 2007Co-Authors: A J Prata, S A Carn, Andreas Stohl, J KerkmannAbstract:Volcanic eruptions emit gases, ash particles and hydrometeors into the atmosphere, occasionally reaching heights of 20 km or more, to reside in the stratospheric overworld where they affect the radiative balance of the atmosphere and the Earth's climate. Here we use satellite measurements and a Lagrangian particle dispersion model to determine the mass loadings, vertical penetration, horizontal extent, dispersion and transport of Volcanic gases and particles in the stratosphere from the Volcanic Cloud emitted during the 20 May 2006 eruption of Soufriere Hills volcano, Montserrat, West Indies. Infrared, ultraviolet and microwave radiation measurements from two polar orbiters are used to quantify the gases and particles, and track the movement of the Cloud for 23 days, over a distance of ~18 000 km. Approximately, 0.1±0.01 Tg(S) was injected into the stratosphere in the form of SO 2 : the largest single sulphur input to the stratosphere in 2006. Microwave Limb Sounder measurements indicate an enhanced mass of HCl of ~0.003–0.01 Tg. Geosynchronous satellite data reveal the rapid nature of the stratospheric injection and indicate that the eruption Cloud contained ~2 Tg of ice, with very little ash reaching the stratosphere. These new satellite measurements of Volcanic gases and particles can be used to test the sensitivity of climate to Volcanic forcing and assess the impact of stratospheric sulphates on climate cooling.
