scholarly journals External surface water influence on explosive eruption dynamics, with implications for stratospheric sulfur delivery and volcano-climate feedback

2021 ◽  
Author(s):  
Colin Rowell ◽  
Mark Jellinek ◽  
Sahand Hajimirza ◽  
Thomas Aubry
Keyword(s):  
Surface Water ◽  
Hydrostatic Pressure ◽  
Mass Flux ◽  
External Surface ◽  
Volcanic Eruptions ◽  
Fold Increase ◽  
Climate Feedback ◽  
Eruption Column ◽  
Eruption Dynamics ◽  
Water Entrainment

Explosive volcanic eruptions can inject sulfur dioxide (SO2) into the stratosphere to form aerosol particles that modify Earth’s radiation balance and drive surface cooling. Eruptions involving interactions with shallow layers (< 500 m) of surface water and ice modify the eruption dynamics that govern the delivery of SO2 to the stratosphere. External surface water potentially controls the evolution of explosive eruptions in two ways that are poorly understood: (1) by modulating the hydrostatic pressure within the conduit and at the vent, and (2) through the ingestion and mixing of external water, which governs fine ash production as well as eruption column buoyancy flux. To make progress, we couple one-dimensional models of magma flow in the conduit and atmospheric column rise through a novel ”magma-water interaction” model that simulates the occurrence, extent and consequences of water entrainment depending on the depth of a surface water layer. We explore the effects of hydrostatic pressure on magma ascent in the conduit and gas decompression at the vent, and the conditions for which water entrainment drives fine ash production by quench fragmentation, eruption column collapse, or outright failure of the jet to breach the water surface. We show that the efficiency of water entrainment into the jet is the predominant control on jet behavior. For an increase in water depth of 50 to 100 m, the critical magma mass eruption rate required for eruption columns to reach the tropopause increases by an order of magnitude. Finally, we estimate that enhanced emission of fine ash leads to up to a 2-fold increase in the mass flux of particles < 125 microns to spreading umbrella clouds, together with up to a 10-fold increase in water mass flux, conditions that can enhance the removal of SO2 via chemical scavenging and ash sedimentation. Overall, compared to purely magmatic eruptions, we suggest that hydrovolcanic eruptions will be characterized by a reduced delivery of SO2 to the stratosphere. Our results thus suggest the possibility of an unrecognized volcano-climate feedback mechanism arising from modification of volcanic climate forcing by direct interaction of erupting magma with varying distributions of water and ice at the Earth’s surface.

scholarly journals Simulation and Analysis of Floodlighting Based on 3D Computer Graphics

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1042
Author(s):  
Rafał Krupiński
Keyword(s):  
Computer Graphics ◽  
External Surface ◽  
Geometric Model ◽  
Three Dimensional ◽  
Fold Increase ◽  
Luminance Level ◽  
Object Model ◽  
Geometric Mesh ◽  
Average Luminance ◽  
To Receive

The paper presents the opportunities to apply computer graphics in an object floodlighting design process and in an analysis of object illumination. The course of object floodlighting design has been defined based on a virtual three-dimensional geometric model. The problems related to carrying out the analysis of lighting, calculating the average illuminance, luminance levels and determining the illuminated object surface area are also described. These parameters are directly tied with the calculations of the Floodlighting Utilisation Factor, and therefore, with the energy efficiency of the design as well as the aspects of light pollution of the natural environment. The paper shows how high an impact of the geometric model of the object has on the accuracy of photometric calculations. Very often the model contains the components that should not be taken into account in the photometric calculations. The research on what influence the purity of the geometric mesh of the illuminated object has on the obtained results is presented. It shows that the errors can be significant, but it is possible to optimise the 3D object model appropriately in order to receive the precise results. For the example object presented in this paper, removing the planes that do not constitute its external surface has caused a two-fold increase in the average illuminance and average luminance. This is dangerous because a designer who wants to achieve a specific average luminance level in their design without optimizing the model will obtain the luminance values that will actually be much higher.

Ensemble-based data assimilation of volcanic aerosols using FALL3D+PDAF

2021 ◽  
Author(s):  
Leonardo Mingari ◽  
Andrew Prata ◽  
Federica Pardini
Keyword(s):  
Data Assimilation ◽  
Information Transfer ◽  
High Performance ◽  
Volcanic Ash ◽  
Numerical Models ◽  
Volcanic Eruptions ◽  
Column Height ◽  
Eruption Column ◽  
Operational Environment ◽  
Assimilation System

&lt;p&gt;Modelling atmospheric dispersion and deposition of volcanic ash is becoming increasingly valuable for understanding the potential impacts of explosive volcanic eruptions on infrastructures, air quality and aviation. The generation of high-resolution forecasts depends on the accuracy and reliability of the input data for models. Uncertainties in key parameters such as eruption column height injection, physical properties of particles or meteorological fields, represent a major source of error in forecasting airborne volcanic ash. The availability of nearly real time geostationary satellite observations with high spatial and temporal resolutions provides the opportunity to improve forecasts in an operational context. Data assimilation (DA) is one of the most effective ways to reduce the error associated with the forecasts through the incorporation of available observations into numerical models. Here we present a new implementation of an ensemble-based data assimilation system based on the coupling between the FALL3D dispersal model and the Parallel Data Assimilation Framework (PDAF). The implementation is based on the last version release of FALL3D (versions 8.x) tailored to the extreme-scale computing requirements, which has been redesigned and rewritten from scratch in the framework of the EU Center of Excellence for Exascale in Solid Earth (ChEESE). The proposed methodology can be efficiently implemented in an operational environment by exploiting high-performance computing (HPC) resources. The FALL3D+PDAF system can be run in parallel and supports online-coupled DA, which allows an efficient information transfer through parallel communication. Satellite-retrieved data from recent volcanic eruptions were considered as input observations for the assimilation system.&lt;/p&gt;

scholarly journals Models of explosive volcanism

1995 ◽  
Vol 2 (3/4) ◽  
pp. 269-279 ◽  
Author(s):  
A. W. Woods ◽  
S. M. Bower ◽  
M. I. Bursik
Keyword(s):  
Mass Flux ◽  
Subsonic Flow ◽  
Supersonic Jet ◽  
Explosive Volcanism ◽  
Eruption Column ◽  
Flow Temperature ◽  
Mean Size ◽  
The Mean ◽  
Size Of Particles ◽  
Residual Ash

Abstract. We describe a series of models which illustrate the controls upon the evolution of an erupting mixture of ash and gas during an explosive volcanic eruption. For large eruption rates, material typically issues from a crater as a supersonic jet which may entrain and heat sufficient air to become buoyant and form a Plinian eruption column. If a buoyant eruption column is able to form, then this column may ascend to heights of order 10-30 km, depending upon the erupted mass flux. In contrast, for low eruption rates, a shock forms in the crater and the material issues as a slow subsonic flow which generates dense hot ash flows. A new model shows that as such ash flows propagate from the vent, the density of the flow decreases mainly due to sedimentation, until ultimately the residual ash flow becomes buoyant. The distance the flow travels before becoming buoyant increases with the mass flux in the current and the mean size of particles in the current, but decreases with the flow temperature. It also depends upon the mass of air entrained into the collapsing fountain. The mass fraction of solid lifted from such ash flows into the ascending cloud depends mainly upon the mass of air entrained into the collapsing fountain near the volcanic vent. We apply our models to predict run-out distances and deposition patterns produced by erupting volcanoes.

scholarly journals Data Assimilation of Volcanic Aerosols using FALL3D+PDAF

2021 ◽  
Author(s):  
Leonardo Mingari ◽  
Arnau Folch ◽  
Andrew T. Prata ◽  
Federica Pardini ◽  
Giovanni Macedonio ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Volcanic Ash ◽  
Volcanic Eruptions ◽  
Column Height ◽  
Model Parameters ◽  
Eruption Column ◽  
Mass Loading ◽  
Multiple Model ◽  
Volcanic Aerosols ◽  
Forecast Quality

Abstract. Modelling atmospheric dispersal of volcanic ash and aerosols is becoming increasingly valuable for assessing the potential impacts of explosive volcanic eruptions on infrastructures, air quality, and aviation. Management of volcanic risk and reduction of aviation impacts can strongly benefit from quantitative forecasting of volcanic ash. However, an accurate prediction of volcanic aerosol concentrations using numerical modelling relies on proper estimations of multiple model parameters which are prone to errors. Uncertainties in key parameters such as eruption column height, physical properties of particles or meteorological fields, represent a major source of error affecting the forecast quality. The availability of near-real-time geostationary satellite observations with high spatial and temporal resolutions provides the opportunity to improve forecasts in an operational context by incorporating observations into numerical models. Specifically, ensemble-based filters aim at converting a prior ensemble of system states into an analysis ensemble by assimilating a set of noisy observations. Previous studies dealing with volcanic ash transport have demonstrated that a significant improvement of forecast skill can be achieved by this approach. In this work, we present a new implementation of an ensemble-based Data Assimilation (DA) method coupling the FALL3D dispersal model and the Parallel Data Assimilation Framework (PDAF). The FALL3D+PDAF system runs in parallel, supports online-coupled DA and can be efficiently integrated into operational workflows by exploiting high-performance computing (HPC) resources. Two numerical experiments are considered: (i) a twin experiment using an incomplete dataset of synthetic observations of volcanic ash and, (ii) an experiment based on the 2019 Raikoke eruption using real observations of SO2 mass loading. An ensemble-based Kalman filtering technique based on the Local Ensemble Transform Kalman Filter (LETKF) is used to assimilate satellite-retrieved data of column mass loading. We show that this procedure may lead to nonphysical solutions and, consequently, conclude that LETKF is not the best approach for the assimilation of volcanic aerosols. However, we find that a truncated state constructed from the LETKF solution approaches the real solution after a few assimilation cycles, yielding a dramatic improvement of forecast quality when compared to simulations without assimilation.

Effect of Passive Surface Water Flux Meter Design on Water and Solute Mass Flux Estimates

2009 ◽  
Vol 14 (12) ◽  
pp. 1334-1342 ◽  
Author(s):  
Julie C. Padowski ◽  
Erin A. Rothfus ◽  
James W. Jawitz ◽  
Harald Klammler ◽  
Kirk Hatfield ◽  
...  
Keyword(s):  
Surface Water ◽  
Mass Flux ◽  
Water Flux

Monitoring super-volcanoes: geophysical and geochemical signals at Yellowstone and other large caldera systems

2006 ◽  
Vol 364 (1845) ◽  
pp. 2055-2072 ◽  
Author(s):  
Jacob B Lowenstern ◽  
Robert B Smith ◽  
David P Hill
Keyword(s):  
North America ◽  
Ground Water ◽  
Mass Flux ◽  
Volcanic Eruptions ◽  
Scientific Study ◽  
Volcanic Events ◽  
Long Valley ◽  
Show Evidence ◽  
The Difference ◽  
The Many

Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of the ground, and considerable heat and mass flux. Because many active and extinct calderas show evidence for repetition of large eruptions, such systems demand detailed scientific study and monitoring. Two calderas in North America, Yellowstone (Wyoming) and Long Valley (California), are in areas of youthful tectonic complexity. Scientists strive to understand the signals generated when tectonic, volcanic and hydrothermal (hot ground water) processes intersect. One obstacle to accurate forecasting of large volcanic events is humanity's lack of familiarity with the signals leading up to the largest class of volcanic eruptions. Accordingly, it may be difficult to recognize the difference between smaller and larger eruptions. To prepare ourselves and society, scientists must scrutinize a spectrum of volcanic signals and assess the many factors contributing to unrest and toward diverse modes of eruption.

scholarly journals Atmospheric processes affecting the separation of volcanic ash and SO<sub>2</sub> in volcanic eruptions: inferences from the May 2011 Grímsvötn eruption

2017 ◽  
Vol 17 (17) ◽  
pp. 10709-10732 ◽  
Author(s):  
Fred Prata ◽  
Mark Woodhouse ◽  
Herbert E. Huppert ◽  
Andrew Prata ◽  
Thor Thordarson ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Early Stage ◽  
Volcanic Eruptions ◽  
Radiation Balance ◽  
Eruption Column ◽  
Density Currents ◽  
Volcanic Emissions ◽  
Main Column ◽  
The Masses ◽  
High Level

Abstract. The separation of volcanic ash and sulfur dioxide (SO2) gas is sometimes observed during volcanic eruptions. The exact conditions under which separation occurs are not fully understood but the phenomenon is of importance because of the effects volcanic emissions have on aviation, on the environment, and on the earth's radiation balance. The eruption of Grímsvötn, a subglacial volcano under the Vatnajökull glacier in Iceland during 21–28 May 2011 produced one of the most spectacular examples of ash and SO2 separation, which led to errors in the forecasting of ash in the atmosphere over northern Europe. Satellite data from several sources coupled with meteorological wind data and photographic evidence suggest that the eruption column was unable to sustain itself, resulting in a large deposition of ash, which left a low-level ash-rich atmospheric plume moving southwards and then eastwards towards the southern Scandinavian coast and a high-level predominantly SO2 plume travelling northwards and then spreading eastwards and westwards. Here we provide observational and modelling perspectives on the separation of ash and SO2 and present quantitative estimates of the masses of ash and SO2 that erupted, the directions of transport, and the likely impacts. We hypothesise that a partial column collapse or sloughing fed with ash from pyroclastic density currents (PDCs) occurred during the early stage of the eruption, leading to an ash-laden gravity intrusion that was swept southwards, separated from the main column. Our model suggests that water-mediated aggregation caused enhanced ash removal because of the plentiful supply of source water from melted glacial ice and from entrained atmospheric water. The analysis also suggests that ash and SO2 should be treated with separate source terms, leading to improvements in forecasting the movement of both types of emissions.

scholarly journals Marked increase in leptospirosis infections in humans and dogs in the Netherlands, 2014

2016 ◽  
Vol 21 (17) ◽  
Author(s):  
Roan Pijnacker ◽  
Marga G.A. Goris ◽  
Margreet J.M. te Wierik ◽  
Els M. Broens ◽  
Joke W.B. van der Giessen ◽  
...  
Keyword(s):  
Surface Water ◽  
Occupational Exposure ◽  
The Netherlands ◽  
Symptom Onset ◽  
Direct Contact ◽  
Early Recognition ◽  
Fold Increase ◽  
Annual Average ◽  
Water Contact ◽  
Mild Winter

In the Netherlands, 97 human leptospirosis cases were notified in 2014. This represents a 4.6-fold increase in autochthonous cases (n = 60) compared with the annual average between 2010 and 2013. Most cases had symptom onset between June and November. This marked increase in humans coincided with an increase of leptospirosis in dogs. In 2014, 13 dogs with leptospirosis were reported, compared with two to six dogs annually from 2010 to 2013. The majority of the autochthonous cases (n = 20) were linked to recreational exposure, e.g. swimming or fishing, followed by occupational exposure (n = 15). About sixty per cent (n = 37) of the autochthonous cases were most likely attributable to surface water contact, and 13 cases to direct contact with animals, mainly rats. A possible explanation for this increase is the preceding mild winter of 2013–2014 followed by the warmest year in three centuries, possibly enabling rodents and Leptospira spp. to survive better. A slight increase in imported leptospirosis was also observed in Dutch tourists (n = 33) most of whom acquired their infection in Thailand (n = 18). More awareness and early recognition of this mainly rodent-borne zoonosis by medical and veterinary specialists is warranted.

scholarly journals Aerosol effects on the cloud-field properties of tropical convective clouds

2013 ◽  
Vol 13 (1) ◽  
pp. 2997-3029 ◽  
Author(s):  
S.-S. Lee ◽  
G. Feingold
Keyword(s):  
Frequency Distribution ◽  
Mass Flux ◽  
Temporal Evolution ◽  
Precipitation Amount ◽  
Fold Increase ◽  
Convective Clouds ◽  
Condensed Water ◽  
Microphysical Processes ◽  
Aerosol Effects ◽  
Convective Mass Flux

Abstract. Aerosol effects on condensed water and precipitation in a tropical cloud system driven by deep convective clouds are investigated for two-dimensional simulations of two-day duration. Although an assumed ten-fold increase in aerosol concentration results in a similar temporal evolution of mean precipitation and a small (9%) difference in cumulative precipitation between the high- and low-aerosol cases, the characteristics of the convection are much more sensitive to aerosol. The convective mass flux, and temporal evolution and frequency distribution of the condensed water path WP (sum of liquid and ice water paths) differ significantly between unperturbed and aerosol-perturbed simulations. There are concomitant differences in the relative importance of individual microphysical processes and the frequency distribution of the precipitation rate (P). With increasing aerosol, (i) the convective mass flux increases, leading to increases in condensation, cloud liquid, and accretion of cloud liquid by precipitation; (ii) autoconversion of cloud water to rain water decreases; (iii) the WP spatial distribution becomes more homogeneous; (iv) there is an increase in the frequencies of high and low WP and P and a decrease in these frequencies at the mid-range of WP and P. Thus while aerosol perturbations have a negligible influence on total precipitation amount, for the case considered, they do have substantial influence on the spatiotemporal distribution of convection and precipitation.

scholarly journals Past 220 year bipolar volcanic signals: remarks on common features of their source volcanic eruptions

2002 ◽  
Vol 35 ◽  
pp. 217-223 ◽  
Author(s):  
Mika Kohno ◽  
Yoshiyuki Fujii
Keyword(s):  
Ice Sheets ◽  
Ice Cores ◽  
Background Level ◽  
Volcanic Eruptions ◽  
Column Height ◽  
Eruption Column ◽  
Low Latitudes ◽  
Explosive Volcanic Eruptions ◽  
The Antarctic ◽  
Santa Maria

AbstractDuring the past 220 years, prominent signals of non-sea salt sulfate ion (nssSO42–) concentration exceeding the background level, including both marine biogenic and anthropogenic SO42–, were found in shallow ice cores from site H15 in East Antarctica and Site-J in southern Greenland. They were mostly correlated with past explosive volcanic eruptions. on the basis of this result and published results of shallow ice cores and snow pits at various locations on the Antarctic and Greenland ice sheets, eight common signals were found, of which six were assigned to the following explosive eruptions: El Chichόn, Mexico, in 1982; Agung, Indonesia, in 1963; Santa Maria, Guatemala, in 1902; Krakatau, Indonesia, in 1883; Cosiguina, Nicaragua, in 1835; an unknown volcano between 1831 and 1834; Tambora, Indonesia, in 1815; and an unknown volcano in 1809. Volcanic eruptions which have a potential to imprint their signals in both the Antarctic and Greenland ice sheets were characterized by (1) location in low latitudes between 20˚N and 10˚ S, and (2) eruption column height ≥25 km, corresponding to a volcanic explosivity index (VEI) ≥5.

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