Volcanic activity occurring in tropical moist atmospheres can promote deep convection and trigger volcanic thunderstorms. These phenomena, however, are rarely observed to last continuously for more ...than a day and so insights into the dynamics, microphysics and electrification processes are limited. Here we present a multidisciplinary study on an extreme case, where volcanically-triggered deep convection lasted for six days. We show that this unprecedented event was caused and sustained by phreatomagmatic activity at Anak Krakatau volcano, Indonesia during 22-28 December 2018. Our modelling suggests an ice mass flow rate of ~5 × 10
kg/s for the initial explosive eruption associated with a flank collapse. Following the flank collapse, a deep convective cloud column formed over the volcano and acted as a 'volcanic freezer' containing ~3 × 10
kg of ice on average with maxima reaching ~10
kg. Our satellite analyses reveal that the convective anvil cloud, reaching 16-18 km above sea level, was ice-rich and ash-poor. Cloud-top temperatures hovered around -80 °C and ice particles produced in the anvil were notably small (effective radii ~20 µm). Our analyses indicate that vigorous updrafts (>50 m/s) and prodigious ice production explain the impressive number of lightning flashes (~100,000) recorded near the volcano from 22 to 28 December 2018. Our results, together with the unique dataset we have compiled, show that lightning flash rates were strongly correlated (R = 0.77) with satellite-derived plume heights for this event.
Between 14 April and 25 May, 2010, Eyjafjallajökull volcano in Iceland erupted a large amount of fine grained ash. Dispersion models and satellite data were used to identify the location of the ash ...cloud, but accurate quantitative forecasts of the concentrations could not be made. By using multispectral satellite measurements from the Spin Enhanced Visible and Infrared Imager (SEVIRI), it is shown that quantitative estimates of the mass loadings (g m−2) can be made with a detection limit ∼0.2 g m−2, every 15 minutes. These data represent the most comprehensive coverage, in space and time, of the Eyjafjallajökull ash and its movement. A new ash concentration chart is proposed that removes the ambiguity inherent in assigning high concentrations to highly negative brightness temperature differences. Validation of satellite ash retrievals against measurements from aircraft, ground‐based lidars, and air quality data is presented. The results show a mean bias of −47 μg m−3 and standard deviation of ±154 μg m−3. The satellite ash retrievals are sufficiently accurate for use with dispersion models to constrain ash concentration forecasts. Concentrations in the dense parts of the dispersing ash cloud occasionally exceeded 4 mg m−3 (∼3% of ash‐affected pixels), and ash clouds with concentrations >2 mg m−3 covered large parts of European airspace on several occasions (∼50% of ash‐affected pixels). The statistical analysis leads naturally to a logarithmic scale for assigning ash concentration limits. We suggest that a better approach is to utilize a dosage and illustrate this using a simple model of ash deposition on jet engines.
Key Points
Quantitative satellite retrievals for volcanic ash are presented and validated
A new ash concentration chart is presented
A new concept for ash thresholds based on dosages is introduced
Mesophotic coral communities are increasingly gaining attention for the unique biological diversity they host, exemplified by the numerous mesophotic fish species that continue to be discovered. In ...contrast, many of the photosynthetic scleractinian corals observed at mesophotic depths are assumed to be depth-generalists, with very few species characterised as mesophotic-specialists. This presumed lack of a specialised community remains largely untested, as phylogenetic studies on corals have rarely included mesophotic samples and have long suffered from resolution issues associated with traditional sequence markers.
Here, we used reduced-representation genome sequencing to conduct a phylogenomic assessment of the two dominant mesophotic genera of plating corals in the Indo-Pacific and Western Atlantic, respectively, Leptoseris and Agaricia. While these genome-wide phylogenies broadly corroborated the morphological taxonomy, they also exposed deep divergences within the two genera and undescribed diversity across the current taxonomic species. Five of the eight focal species consisted of at least two sympatric and genetically distinct lineages, which were consistently detected across different methods.
The repeated observation of genetically divergent lineages associated with mesophotic depths highlights that there may be many more mesophotic-specialist coral species than currently acknowledged and that an urgent assessment of this largely unstudied biological diversity is warranted.
Satellite instruments have been providing measurements of global volcanic emissions of sulfur dioxide (SO2) since 1978, based on observations in the ultraviolet (UV), infrared (IR) and microwave ...spectral bands. We review recent advances in satellite remote sensing of volcanic gases, focusing on increased instrument sensitivity to tropospheric SO2 emissions and techniques to determine volcanic plume altitude. A synthesis of ~36years of global UV, IR and microwave satellite measurements yields an updated assessment of the volcanic SO2 flux to the upper troposphere and lower stratosphere (UTLS) between 1978 and 2014 (~1–2Tg/yr). The present availability of multiple UV and IR satellite SO2 products provides increased confidence in calculated SO2 loadings for many eruptions. We examine the temporal and latitudinal distribution of volcanic SO2 emissions and reassess the relationship between eruptive SO2 discharge and eruption magnitude, finding a first-order correlation between SO2 emission and volcanic explosivity index (VEI), but with significant scatter. Based on the observed SO2-VEI relation, we estimate the fraction of eruptive SO2 emissions released by the smallest eruptions (~0.48Tg/yr), which is not recorded by satellite observations. A detailed breakdown of the sources of measured SO2 emissions reveals intuitively expected correlations between eruption frequency, SO2 loading and volcanic degassing style. We discuss new constraints on e-folding times for SO2 removal in volcanic plumes, and highlight recent measurements of volcanic hydrogen chloride (HCl) injections into the UTLS. An analysis of passive volcanic emissions of SO2 detected in Ozone Monitoring Instrument (OMI) SO2 data since 2004 provides new insight into the location and stability of the dominant sources of volcanic SO2 over the past decade. Since volcanic SO2 emissions constitute a random, highly variable perturbation to the atmosphere-climate system, continued monitoring of volcanic SO2 emissions from space by multiple UV and IR instruments to extend the current multi-decadal record is essential, and near-global, geostationary measurements of SO2 may be available by the end of the current decade.
•New synthesis of ~36years of satellite measurements of volcanic degassing.•New publicly available database of volcanic sulfur dioxide (SO2) emissions measured by satellite remote sensing.•Review of satellite measurements of SO2 and other volcanic gases including hydrogen chloride and hydrogen sulfide.•Updated assessment of the volcanic SO2 flux to the upper troposphere and lower stratosphere (UTLS) between 1978 and 2014.•New satellite-based constraints on the strongest sources of passive volcanic degassing.
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 SO₂) 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 SO₂ observations of the spread of volcanic clouds.
Mount Kelut (Indonesia) erupted explosively around 15:50 UT on 13 February 2014 sending ash and gases into the stratosphere. Satellite ash retrievals and dispersion transport modeling are combined ...within an inversion framework to estimate the volcanic ash source term and to study ash transport. The estimated source term suggests that most of the ash was injected to altitudes of 16–17 km, in agreement with space‐based lidar data. Modeled ash concentrations along the flight track of a commercial aircraft that encountered the ash cloud indicate that it flew under the main ash cloud and encountered maximum ash concentrations of 9 ± 3 mg m−3, mean concentrations of 2 ± 1 mg m−3over a period of 10–11 min of the flight, giving a dosage of 1.2 ± 0.3 g s m−3. Satellite data could not be used directly to observe the ash cloud encountered by the aircraft, whereas inverse modeling revealed its presence.
Key Points
Combining satellite retrievals and modeling gives valuable information
Volcanic ash source term is constrained by satellite observations
Estimates of modeled ash concentrations encountered by a commercial aircraft
•Experimental results of a novel rotary active magnetic refrigerator are obtained.•Experiments are compared to predictions from a 1D numerical AMR model.•Performance is evaluated considering ...parasitic losses for a range of conditions.•A cooling power of 200W is produced at a span of 16.8K with a COP of 0.69.•The attained overall second-law efficiency is around 5%.
Performance results for a novel rotary active magnetic regenerator (AMR) and detailed numerical model of it are presented. The experimental device consists of 24 regenerators packed with gadolinium (Gd) spheres rotating inside a four-pole permanent magnet with magnetic field of 1.24T. A parametric study of the temperature span, cooling power, coefficient of performance (COP) and efficiency of the system was carried out over a range of different hot reservoir temperatures, volumetric flow rates and cooling powers. Detailed modeling of the AMR using a 1D model was performed and compared with the experimental results. An overall mapping of the thermal losses of the system was performed, and good agreement between the experimental and numerical results was found when parasitic heat losses were subtracted from the modeling results. The performance of the system was evaluated via the COP, the exergetic-equivalent cooling power (ExQ), and the overall second law efficiency, η2nd. Losses mapping indicated that friction and thermal leakage to the ambient are the most important contributors to the reduction of the system performance. Based on modeling results, improvements on the flow distributor design and reduction of the cold end thermal parasitic losses are expected to enhance the efficiency of the system. For an operating frequency of 1.5Hz, a volumetric flow rate of 400L/h, a hot reservoir temperature of 297.7K, and thermal loads of 200 and 400W, the obtained temperature spans, ΔTS, were 16.8K and 7.1K, which correspond to COPs of 0.69 and 1.51, respectively. The maximum overall second-law efficiency was 5.6% for a ΔTS of 12.9K at 500L/h and 400W.
Volcanic ash and sulphur dioxide masses from the November 2005 eruption of Karthala volcano, Comoros Islands, are simultaneously retrieved using rapid‐scan, multispectral infrared measurements from ...the Spin Enhanced Visible and Infrared Imager on board the Meteosat Second Generation geosynchronous satellite. Retrievals are made every 15 min, which show that the ash and SO2 separate in the vertically sheared atmosphere producing a fast moving upper level (∼12 km) SO2 cloud, a slower moving middle level (∼8 km) ash cloud and a boundary layer (<3 km) SO2 plume. The total mass of fine ash is 0.1 ± 0.05 Tg (SiO2), the upper level SO2 mass is 0.19 ± 0.01 Tg (S) while the boundary layer SO2 mass is 0.009 ± 0.01 Tg (S). These are the first simultaneous satellite measurements of ash and SO2 from an erupting volcano and confirm previous ideas about vertical separation. We suggest care must be exercised when using SO2 as a tracer for volcanic ash in aviation hazard warning systems.
Scorpion venom causes renal injury and affects vascular ion-channels function. Centruroides margaritatus scorpion is found in Colombia and is frequently the cause of envenomation accidents; however, ...its renal impact has never been investigated.
To evaluate the effects of C. margaritatus venom (CmV) on renal parameters using isolated rat kidney and renal cell culture models.
Wistar rats (n = 5, weighing 240-300 g) were first perfused with Krebs-Henseleit solution containing 6 g 100 mL-1 bovine serum albumin. After 30 minutes, the kidneys were perfused with CmV to a final concentration of 10 μgmL-1; evaluation was performed by measuring Perfusion Pressure (PP), Renal Vascular Resistance (RVR), Urinary Flow (UF), Glomerular Filtration Rate (GFR), and percentage of electrolyte tubular transport. Moreover, kidney histological analyses and cell cytotoxicity in renal tubule epithelial cells (MDCK) and proximal tubular cells (LLC-MK2) were assessed.
CmV increased PP and RVR 60 min after perfusion. On the other hand, UF, GFR, and the percentages of sodium, potassium and chloride tubular transport decreased after experimental envenomation. UF dropped after 120 min, while GFR and percentage of electrolyte tubular transport diminished after 60, 90 and 120 min. CmV was not toxic to MDCK cell line but reduced the viability of LLC-MK2 cells at concentrations ranging from 6.25 to 200 μgmL-1. Histological analyses disclosed hydropic degeneration, edema, and protein deposits. Flow cytometry disclosed that cell death occurred predominantly by necrosis.
Our results suggest that C. margaritatus venom can trigger renal impairment, mainly in the proximal kidney tubule.
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