Modelling the volcanic ash plume from Eyjafjallajökull eruption (May 2010) over Europe: evaluation of the benefit of source term improvements and of the assimilation of aerosol measurements

Numerical dispersion models are used operationally worldwide to mitigate the effect of volcanic ash on aviation. In order to improve the representation of the horizontal dispersion of ash plumes and of the 3D concentration of ash, a study was conducted using the MOCAGE model during the European Natural Airborne Disaster Information and Coordination System for Aviation (EUNADICS-AV) project. Source term modelling and assimilation of different data were investigated. A sensitivity study of source term formulation showed that a resolved source term, using the FPLUME plume rise model in MOCAGE, instead of a parameterised source term, induces a more realistic representation of the horizontal dispersion of the ash plume. The FPLUME simulation provides more concentrated and focused ash concentrations in the horizontal and the vertical dimensions than the other source term. The assimilation of Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth has an impact on the horizontal dispersion of the plume, but this effect is rather low and local compared to source term improvement. More promising results are obtained with the continuous assimilation of ground-based lidar profiles, which improves the vertical distribution of ash and helps in reaching realistic values of ash concentrations. Using this configuration, the effect of assimilation may last for several hours and it may propagate several hundred kilometres downstream of the lidar profiles.

Estimating the Volcanic Ash Plume Course, PM2.5 Emissions, and Environmental Impacts Based on the December 4, 2021, Mount Semeru Eruption

Recently on the December 4, 2021 at 03:00 PM, 3676 m high Mount Semeru located in the East parts of Java Island has erupted. To our best knowledge, an immediate and rapid systematic analysis of the volcanic ash plume courses, PM2.5 emissions, and environmental impacts based on Mount Semeru eruption has not been implemented so far. Then, this research aims to provide and fill the research gap on the rapid assessment of recent Mount Semeru eruption. From the result, it is clearly visible that for 12 hours the volcanic ash plume course was eastward. The volcanic ash plume can travel a distance of 0–10 km to the North and South directions, and more than 10 km to the East direction. The size of the volcanic ash plume was large at 02:00 AM on December 5, 2021. The smallest size of a volcanic ash plume was recorded at 09:00 PM on December 4, 2021. Most parts of the ash plume (55.98%) or equals 39.01 km2 contain fallen volcanic material amounts ranged from 1 kg/m2 to 10 kg/m2. The fallen volcanic material amount peaked between 08:00 PM and 11:00 PM. Based on the estimation, the PM2.5 content in the atmosphere increased after the eruption. The mean of PM2.5 before the eruption was 48.5 ± 19.3(95%CI: 29.2 to 67.8 ug/m3). While after eruption the mean of PM2.5 was 79.4 ± 32.2(95%CI: 47.2 to112 ug/m3). It indicated that the Mount Semeru eruption has increased the PM2.5 equals 63.65%.

Classifying Major Explosions and Paroxysms at Stromboli Volcano (Italy) from Space

Stromboli volcano has a persistent activity that is almost exclusively explosive. Predominated by low intensity events, this activity is occasionally interspersed with more powerful episodes, known as major explosions and paroxysms, which represent the main hazards for the inhabitants of the island. Here, we propose a machine learning approach to distinguish between paroxysms and major explosions by using satellite-derived measurements. We investigated the high energy explosive events occurring in the period January 2018–April 2021. Three distinguishing features are taken into account, namely (i) the temporal variations of surface temperature over the summit area, (ii) the magnitude of the explosive volcanic deposits emplaced during each explosion, and (iii) the height of the volcanic ash plume produced by the explosive events. We use optical satellite imagery to compute the land surface temperature (LST) and the ash plume height (PH). The magnitude of the explosive volcanic deposits (EVD) is estimated by using multi-temporal Synthetic Aperture Radar (SAR) intensity images. Once the input feature vectors were identified, we designed a k-means unsupervised classifier to group the explosive events at Stromboli volcano based on their similarities in two clusters: (1) paroxysms and (2) major explosions. The major explosions are identified by low/medium thermal content, i.e., LSTI around 1.4 °C, low plume height, i.e., PH around 420 m, and low production of explosive deposits, i.e., EVD around 2.5. The paroxysms are extreme events mainly characterized by medium/high thermal content, i.e., LSTI around 2.3 °C, medium/high plume height, i.e., PH around 3330 m, and high production of explosive deposits, i.e., EVD around 10.17. The centroids with coordinates (PH, EVD, LSTI) are: Cp (3330, 10.7, 2.3) for the paroxysms, and Cme (420, 2.5, 1.4) for the major explosions.

Anatomy of a Paroxysmal Lava Fountain at Etna Volcano: The Case of the 12 March 2021, Episode

On 13 December 2020, Etna volcano entered a new eruptive phase, giving rise to a number of paroxysmal episodes involving increased Strombolian activity from the summit craters, lava fountains feeding several-km high eruptive columns and ash plumes, as well as lava flows. As of 2 August 2021, 57 such episodes have occurred in 2021, all of them from the New Southeast Crater (NSEC). Each paroxysmal episode lasted a few hours and was sometimes preceded (but more often followed) by lava flow output from the crater rim lasting a few hours. In this paper, we use remote sensing data from the ground and satellite, integrated with ground deformation data recorded by a high precision borehole strainmeter to characterize the 12 March 2021 eruptive episode, which was one of the most powerful (and best recorded) among that occurred since 13 December 2020. We describe the formation and growth of the lava fountains, and the way they feed the eruptive column and the ash plume, using data gathered from the INGV visible and thermal camera monitoring network, compared with satellite images. We show the growth of the lava flow field associated with the explosive phase obtained from a fixed thermal monitoring camera. We estimate the erupted volume of pyroclasts from the heights of the lava fountains measured by the cameras, and the erupted lava flow volume from the satellite-derived radiant heat flux. We compare all erupted volumes (pyroclasts plus lava flows) with the total erupted volume inferred from the volcano deflation recorded by the borehole strainmeter, obtaining a total erupted volume of ~3 × 106 m3 of magma constrained by the strainmeter. This volume comprises ~1.6 × 106 m3 of pyroclasts erupted during the lava fountain and 2.4 × 106 m3 of lava flow, with ~30% of the erupted pyroclasts being remobilized as rootless lava to feed the lava flows. The episode lasted 130 min and resulted in an eruption rate of ~385 m3 s−1 and caused the formation of an ash plume rising from the margins of the lava fountain that rose up to 12.6 km a.s.l. in ~1 h. The maximum elevation of the ash plume was well constrained by an empirical formula that can be used for prompt hazard assessment.

A mosaic of phytoplankton responses across Patagonia, the southeast Pacific and the southwest Atlantic to ash deposition and trace metal release from the Calbuco volcanic eruption in 2015

Following the eruption of the Calbuco volcano in April 2015, an extensive ash plume spread across northern Patagonia and into the southeast Pacific and southwest Atlantic oceans. Here, we report on field surveys conducted in the coastal region receiving the highest ash load following the eruption (Reloncaví Fjord). The fortuitous location of a long-term monitoring station in Reloncaví Fjord provided data to evaluate inshore phytoplankton bloom dynamics and carbonate chemistry during April–May 2015. Satellite-derived chlorophyll a measurements over the ocean regions affected by the ash plume in May 2015 were obtained to determine the spatial–temporal gradients in the offshore phytoplankton response to ash. Additionally, leaching experiments were performed to quantify the release from ash into solution of total alkalinity, trace elements (dissolved Fe, Mn, Pb, Co, Cu, Ni and Cd) and major ions (F−, Cl−, SO42-, NO3-, Li+, Na+, NH4+, K+, Mg2+ and Ca2+). Within Reloncaví Fjord, integrated peak diatom abundances during the May 2015 austral bloom were approximately 2–4 times higher than usual (up to 1.4 × 1011 cells m−2, integrated to 15 m depth), with the bloom intensity perhaps moderated due to high ash loadings in the 2 weeks following the eruption. Any mechanistic link between ash deposition and the Reloncaví diatom bloom can, however, only be speculated on due to the lack of data immediately preceding and following the eruption. In the offshore southeast Pacific, a short-duration phytoplankton bloom corresponded closely in space and time to the maximum observed ash plume, potentially in response to Fe fertilisation of a region where phytoplankton growth is typically Fe limited at this time of year. Conversely, no clear fertilisation on the same timescale was found in the area subject to an ash plume over the southwest Atlantic where the availability of fixed nitrogen is thought to limit phytoplankton growth. This was consistent with no significant release of fixed nitrogen (NOx or NH4) from Calbuco ash. In addition to the release of nanomolar concentrations of dissolved Fe from ash suspended in seawater, it was observed that low loadings (< 5 mg L−1) of ash were an unusually prolific source of Fe(II) into chilled seawater (up to 1.0 µmol Fe g−1), producing a pulse of Fe(II) typically released mainly during the first minute after addition to seawater. This release would not be detected (as Fe(II) or dissolved Fe) following standard leaching protocols at room temperature. A pulse of Fe(II) release upon addition of Calbuco ash to seawater made it an unusually efficient dissolved Fe source. The fraction of dissolved Fe released as Fe(II) from Calbuco ash (∼ 18 %–38 %) was roughly comparable to literature values for Fe released into seawater from aerosols collected over the Pacific Ocean following long-range atmospheric transport.

Modelling the volcanic ash plume from Eyjafjallajökull eruption (May 2010) over Europe: evaluation of the benefit of source term improvements and of the assimilation of aerosol measurements

Numerical dispersion models are used operationally worldwide to mitigate the effect of volcanic ash on aviation. In order to improve the representation of the horizontal dispersion of ash plumes and of the 3D concentration of ash, a study was conducted using the MOCAGE model during the EUNADICS-AV project. Source term modelling and assimilation of different data were investigated. A sensitivity study to source term formulation showed that a resolved source term, using the FPLUME plume-rise model in MOCAGE, instead of a parameterised source term, induces a more realistic representation of the horizontal dispersion of the ash plume. The FPLUME simulation provides more concentrated and focused ash concentrations in the horizontal and the vertical dimensions than the other source term. The assimilation of MODIS Aerosol Optical Depth has an impact on the horizontal dispersion the plume, but this effect is rather low and local, compared to source term improvement. More promising results are obtained with the continuous assimilation of ground-based lidar profiles, which improves the vertical distribution of ash and helps to reach realistic values of ash concentrations. The improvement can remain several hours after and several hundred kilometers away downstream to the assimilated profiles.

PUFF Model Prediction of Volcanic Ash Plume Dispersal for Sakurajima Using MP Radar Observation

In this study, a real-time volcanic ash plume prediction by the PUFF system was applied to the Sakurajima volcano (which erupted at 17:24 Japan Standard Time (JST) on 8 November 2019), using the direct observation of the multi-parameter (MP) radar data installed at the Sakurajima Volcano Research Center. The MP radar showed a plume height of 5500 m a.s.l. around the volcano. The height was higher than the 4000 m by the PUFF system, but was lower than the observational report of 6500 m by the Japan Meteorological Agency in Kagoshima. In this study, ash particles by the MP radar observation were assimilated to the running PUFF system operated by the real-time emission rate and plume height, since the radar provides accurate plume height. According to the simulation results, the model prediction has been improved in the shape of the ash cloud with accurate plume top by the new MP radar observation. The plume top is corrected from 4000 m to 5500 m a.s.l., and the three-dimensional (3D) ash dispersal agrees with the observation. It was demonstrated by this study that the direct observation of MP radar obviously improved the model prediction, and enhanced the reliability of the prediction model.

A mosaic of phytoplankton responses across Patagonia, the SE Pacific and SW Atlantic Ocean to ash deposition and trace metal release from the Calbuco 2015 volcanic eruption

Following the April 2015 eruption of the Calbuco volcano, an extensive ash plume spread across northern Patagonia and into the SE Pacific and SW Atlantic Ocean. Here we report the results of field surveys conducted in the marine region receiving the highest ash load following the eruption (Reloncaví Fjord). The fortuitous location of a long-term monitoring station in Reloncaví Fjord provided data to evaluate inshore phytoplankton bloom dynamics and carbonate chemistry during April–May 2015. Satellite derived chlorophyll-a measurements over the ocean regions affected by the ash plume in May 2015 were obtained to determine the spatial-temporal gradient in offshore phytoplankton response to ash. Additionally, leaching experiments were performed to quantify the release of total alkalinity, trace elements (Fe, Mn, Pb, Co, Cu, Ni and Cd) and major ions (Fl, Cl, SO4, NO3, Li, Na, NH4, K, Mg, Ca) from ash into solution. Within Reloncaví Fjord, integrated peak diatom abundances during the May 2015 austral bloom were higher than usual (up to 1.4 × 1011 cells m−2, integrated to 15 m depth), with the bloom intensity perhaps moderated due to high ash loadings in the two weeks following the eruption. In the offshore SE Pacific, a short duration phytoplankton bloom corresponded closely in space and time to the maximum observed ash plume, potentially in response to Fe-fertilization of a region where phytoplankton growth is typically Fe-limited at this time of year. Conversely, no clear fertilization was found in the area subject to an ash plume over the SW Atlantic where the availability of fixed nitrogen is thought to limit phytoplankton growth which was consistent with no significant release of fixed nitrogen from ash. In addition to release of nanomolar concentrations of dissolved Fe from ash suspended in seawater, it was observed that low loadings (

Design and Preliminary Testing of the Volcanic Ash Plume Receiver Network

The presence of volcanic ash in the signal path between a GPS satellite and a ground-based receiver strongly correlates with a decrease in GPS signal strength. This effect has been seen in data collected from GPS sites located near active volcanoes; however, the sparse placement of existing GPS sites limits the applicability of this technique as an ash plume detection method to relatively few well-instrumented volcanoes. This deficiency has motivated the development of a low-cost distributed sensor system based on navigation-grade GPS receivers, which can take advantage of attenuated GPS signals to increase the quality and availability of real-time ash plume observations during an eruption. This GPS-based system has been designed specifically to meet remote sensing needs while operating autonomously in difficult conditions and minimizing on-site infrastructure requirements. Prototypes of this system have undergone long-term testing and the data collected from this testing have been used to develop the additional processing steps necessary to account for the different behavior of navigation grade GPS equipment compared to the geodetic equipment used at existing GPS sites.