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The present investigation centers on the impact of viscous dissipation and ohmic heating on the plume generated by a line heat source under the impact of an aligned magnetic field. In this study, the flow model is adapted to incorporate ohmic heating and viscous dissipation by including the respective terms in the energy equation. A mathematical model is formulated as a system of coupled partial differential equations to analyze the flow problem. Subsequently, a numerical solution is derived with stream function formulation for the system of coupled partial differential equations, which transmutes it into ordinary differential equations. To achieve this, the numerical properties of the problem are established through the utilization of the Shooting method in tandem with the MATLAB tool bvp4c. The graphical representations of both missing and specified boundary conditions depict the effects of the magnetic parameter, viscous dissipation variable, magnetic force parameter, Prandtl number, and magnetic Prandtl number. These are accompanied by a discussion of their respective physical implications. The observed results claimed that the velocity, current density, and temperature distribution decrease for enhancing magnetic parameters. Meanwhile, the skin friction and magnetic flux drop while the heat transfer rate increases with an increment in magnetic parameters. These fluid flow and heat transfer characteristics were observed to decrease for increasing viscous dissipation. The current work is novel in incorporating ohmic heating viscous dissipation in energy equations coupled with Max-well and magnetic induction equations. [ABSTRACT FROM AUTHOR]

Hydrothermal vents emit hot fluids enriched in energy sources for microbial life. Here, we compare the ecological and biogeochemical effects of hydrothermal venting of two recently discovered volcanic seamounts, Polaris and Aurora of the Gakkel Ridge, in the ice-covered Central Arctic Ocean. At both sites, persistent hydrothermal plumes increased up to 800  m into the deep Arctic Ocean. In the two non-buoyant plumes, rates of microbial carbon fixation were strongly elevated compared to background values of 0.5–1  μmol  m−3 day−1 in the Arctic deep water, which suggests increased chemoautotrophy on vent-derived energy sources. In the Polaris plume, free sulfide and up to 360  nM hydrogen enabled microorganisms to fix up to 46  μmol inorganic carbon (IC) m−3 day−1 . This energy pulse resulted in a strong increase in the relative abundance of SUP05 by 25% and Candidatus Sulfurimonas pluma by 7% of all bacteria. At Aurora, microorganisms fixed up to 35  μmol IC m−3 day−1 . Here, metal sulfides limited the bioavailability of reduced sulfur species, and the putative hydrogen oxidizer Ca. S. pluma constituted 35% and SUP05 10% of all bacteria. In accordance with this data, transcriptomic analysis showed a high enrichment of hydrogenase-coding transcripts in Aurora and an enrichment of transcripts coding for sulfur oxidation in Polaris. There was neither evidence for methane consumption nor a substantial increase in the abundance of putative methanotrophs or their transcripts in either plume. Together, our results demonstrate the dominance of hydrogen and sulfide as energy sources in Arctic hydrothermal vent plumes. [ABSTRACT FROM AUTHOR]

ABSTRACT The Northwest Himalayan region has a record of several phases of mafic magmatic activity spanning from Precambrian to Cenozoic in a dynamic tectonic setting. Here, we studied detailed petrography and new whole‐rock geochemistry of mafic volcanic and dykes from the Nagrota–Kathindi Section (NKS), Himachal region of the NW Himalaya, to understand the petrogenesis and possible tectonic setting. Both rock types have comparable mineralogical compositions (clinopyroxene + plagioclase + actinolite‐tremolite + chlorite + iron oxides ± hornblende ± epidote ± quartz ± carbonates) overprinted by greenschist to lower amphibolite facies metamorphism. The mafic volcanic and dykes of NKS exhibit subalkaline basalts to basaltic andesites and a typical tholeiite compositional character. The chondrite‐normalized rare earth element pattern exhibits similar LREE‐enrichment and strong HREE‐fractionation, whereas primitive mantle‐normalized multi‐element patterns show pronounced LILE‐enrichment of Rb, Ba, Th, LREE, and HFSE depletion of Nb, K, P, and Ti. The Zr–Y–Nb–Th relationships indicate that both rock types were derived from the plume source, whereas low Nb/La (< 1), similar high large‐ion lithophile element concentrations, and pronounced negative Nb, Zr, P, and Ti anomalies suggest that components other than mantle plume must have been involved in the generation and evolution of both rock types, that is, most likely plume and subcontinental lithosphere mantle (SCLM) interaction. The genesis of parent magma for the NKS volcanic and dykes was derived by 4%–6% and 10%–20% partial melting from the spinel + garnet lherzolite stability field. The majority of the studied samples correspond to spinel + garnet peridotite melting on (Gd/Yb)N versus CaO/Al2O3 diagram, thereby corroborating residual garnet in the mantle restite. All the basalts and dykes from the NK section did erupt/intrude in an intracontinental rift setting based on geochemical discrimination. The key petro‐tectonic processes attributed to the formation of these rocks are as follows: (i) the melting of the ascending plume by adiabatic decompression; (ii) the partial melting of this plume–SCLM source in the melting regime, which produces basaltic magma with a tholeiitic composition; and (iii) the release of heat that provides the thermal condition for melting of SCLM and interaction between upwelling mantle plume and subduction metasomatized SCLM. [ABSTRACT FROM AUTHOR]

Consideration is given to a mathematical model for the formation of hydrates in a jet flow of hydrocarbons for two initial stages (submerged jet and plume). The purpose of the mathematical modeling is to investigate the effects of various compositions of jet flow components on the dynamics of hydrate formation. The object of investigation is a jet flow of hydrocarbons occurring in technogenic spills. The current importance of this investigation is associated with the need to predict the dynamics of oil and gas propagation for cases of technogenic accidents in deepwater development of deposits. A mathematical model has been created for a jet flow for two initial stages with account for the influence of the composition of the flow components. Computational experiments have been carried out for various initial values of pressure and oil volume content in the jet with a view to assessing the dynamics of gas hydrate formation in oil emulsion. The results of the mathematical modeling included the following dependences obtained for various versions of the composition of jet flow components: dependence of the temperature and mass of the newly formed hydrate on the vertical coordinate and the dynamics of variation in the radius of the hydration shell in bubbles. As a result of comparison of the results of a laboratory experiment with the results of mathematical modeling a high-quality agreement has been obtained. [ABSTRACT FROM AUTHOR]

The intense interaction between thruster plumes and spacecraft surfaces presents substantial challenges for the advancement of space technologies. The impingement effects from a 10 N bipropellant thruster plume on a vertical instrumented plate were experimentally and numerically investigated in this study. Impingement pressure and heat flux were measured using micro differential pressure transducers and Gardon gauges, respectively, while the spatial distribution of the plume was captured using the high-speed camera. The phenomena and the distribution characteristics of plume impingement have been summarized, thereby providing a comprehensive validation dataset for subsequent predictions. Numerical simulations are conducted utilizing the coupled hybrid Computational Fluid Dynamics and Direct Simulation Monte Carlo (CFD-DSMC) algorithm. The dependence of the simulation outcomes on grid resolution was critically assessed, and the accuracy of the results was validated by comparison with experimental data. An integrated methodology, combining experimental and numerical approaches, was developed to calculate the maximum heat flux under realistic grid configurations. This method has proven to be effective and supports the accurate and efficient evaluation of intense plume impingement effects for engineering applications. • Systematic experimental data and key features of intense plume impingement effects. • Sensitivity analysis of simulated impingement data to grid configurations. • Validation of simulation methods through comparative analysis with experimental data. • Integrative approach for engineering calculation of impingement heat flux. [ABSTRACT FROM AUTHOR]

This work presents new data on the Sm–Nd age of the Ishlya (1470 ± 62 Ma) and Misaelga (1481 ± 58 Ma) mafic/ultramafic complexes distributed along the western slope of the Southern Urals. The ages obtained are close to the Calymmian–Ectasian boundary (~1400 Ma) of the International Chronostratigraphic Scale. Based on calculated data, it is shown that the area of magma generation for the melts that formed the named complexes has been located in the "head" of a plume, which is the primary cause of the Mashak "magmatic event" in the Southern Urals. [ABSTRACT FROM AUTHOR]

During the normal operation of cooling towers in nuclear power plants, water vapor with a certain temperature is discharged through the outlet of the cooling tower, which mixes with the surrounding air. A portion of this vapor condenses and forms visible plumes. This paper uses Computational fluid dynamics (CFD) numerical simulation software to simulate six nuclear power units and their supporting cooling towers at a nuclear power plant site, and studies the impact of plumes emitted from the six cooling towers under different wind directions on the radioactive diffusion of the nuclear power plant discharge. The research results indicate that when the arrangement direction of the cooling towers is consistent with the wind direction，the influence of the cooling towers on the environmental flow field extends to a distance of approximately 1 500 m in the downwind direction. When the cooling towers are located in the downwind direction of the reactor unit, the emission from the cooling towers increases the pollution diffusion factor within a 1 000 m range of the chimney. As the environmental wind speed increases, the impact of the cooling tower emissions on the diffusion of pollutants from the chimney decreases.

Abstract Laser powder bed fusion (LPBF) is an additive manufacturing technology with high practical value. In order to improve the quality of the fabricated parts, process monitoring has become a crucial solution, offering the potential to ensure manufacturing stability and repeatability. However, a cardinal challenge involves discerning a precise correlation between process characteristics and potential defects. This paper elucidates the integration of an off-axis vision monitoring mechanism via a high-speed camera focused on capturing the single-track melting phenomenon. An innovative image processing method was devised to segment the plume and spatters, while Kalman filter was employed for multi-object tracking of the spatters. The features of both the plume and spatters were extracted, and their relationship with molten states was investigated. Finally, the PSO-XGBoost algorithm was utilized to identify five molten states, achieving an accuracy of 92.16%. The novelty of this approach resides in its unique combination of plume characteristics, spatter features, and computationally efficient machine learning models, which collectively address the challenge of limited field of view prevalent in real production scenarios, thereby enhancing process monitoring efficacy. Relative to existing methodologies, the proposed PSO-XGBoost approach offers heightened accuracy, convenience, and appropriateness for the monitoring of the LPBF process. This work provides an effective and novel approach to monitor the LPBF process and evaluate the part fabrication quality for complex and changeable working conditions.

Plume are common physical phenomena in fiber laser keyhole welding and have serious negative effects on the welding process. Based on this, this paper explores the regulation law of conventional shielding gas flow on plume. The results show that the shielding gas has a very significant effect on the suppression of the slender part of the plume, and the greater the gas flow rate, the better the plume removal effect. The addition of the shielding gas makes the welding process more stable, the molten pool flows stably, and the frequency of spatter eruption is reduced. Under the experimental conditions, the optimal shielding gas flow rate is around 15 l/min, and the penetration depth and width are increased by about 10% and decreased by about 22%, respectively, compared with that without adding the shielding gas. Based on the gas flow simulation, the gas flow pressure (about 132 Pa) generated by an appropriate amount of shielding gas (about 15 l/min) can press the liquid column and spatter near the keyhole mouth into the molten pool to avoid the spatter eruption. Excessive shielding gas flow will interfere with the flow of the molten pool excessively, and the weld surface will show a serious undercut phenomenon. [ABSTRACT FROM AUTHOR]

This study focuses on how the porous medium affects the plume generated due to line heat source when an aligned magnetic field is present. For this study, the momentum equation of the flow model is modified for porous medium by including the porosity term. A mathematical model is developed as coupled partial differential equations in order to study the flow problem. Later, a numerical solution is found for the system of coupled partial differential equations that are transmuted in to ordinary differential equations. For this purpose, the numerical characteristics of the problem are derived employing a shooting approach in combination with the built-in MATLAB tool bvp4c. The graphical illustrations of missing and specified boundary conditions demonstrate the impacts of porosity parameter Ω, magnetic force parameter S, Prandtl number Pr and magnetic Prandtl number γ accompanied by a discussion of their corresponding physical implications. The novelty of this developed problem is proclaimed with justification by its emphasis on the principal characteristics of heat and fluid flow affected predominantly by the presence of a porous medium. The thorough examination of the porosity parameter Ω for missing conditions depicts that the temperature and velocity profiles enhance while current density drops for the increasing values of the porosity parameter Ω. Whereas, for specified conditions, the skin friction and magnetic flux enhance but heat transfer rate declines with increment in Ω. [ABSTRACT FROM AUTHOR]

There is considerable interest in sending a mission to Enceladus to sample its erupting materials, which are sourced from its ocean, a proposed habitable environment. However, we lack resolution between competing ascent and eruption models, which offer differing consequences and challenges for mission sampling and access strategies. We report a new Enceladus ascent and eruption model, "Cryo‐Erupt," where ascent from ocean to jet is driven by the exsolution and expansion of dissolved gases from ascending water within conduits. This mechanism shares many similarities with some forms of terrestrial activity, including explosive silicate volcanism, cold‐water geysers and "limnic" eruptions. This preliminary study suggests that this mode of ascent and eruption is viable and broadly consistent with a range of observations including the apparent co‐existence of point‐ (jet) and fissure‐ (curtain) sourced activity as well as strong contrasts in velocity and ice‐to‐vapor ratio between the plume and the jets feeding it. However, it requires the co‐existence of a sublimation plume as an additive component to the broader plume. The outcomes of the Cryo‐Erupt model differ in terms of conduit physical and chemical processes from previously proposed boiling interface eruption models, for example, predicting larger dynamic pressures and narrower conduits, which could present challenges for direct robotic access. Due to the lack of a static boiling interface or wall condensation, bulk composition is unlikely to change appreciably during ascent from the ocean‐conduit interface to the jet, potentially simplifying the interpretation of samples collected in space or on Enceladus' surface. Plain Language Summary: High‐speed jets from giant ice fissures on Saturn's moon Enceladus feed a large plume, which is of interest to scientists because it contains salts and organic compounds, which are evidence of a subsurface ocean that may possibly host life. However, it is unclear how the chemistry of the plume material (gas and grains) might be altered as this material moves from the ocean into space, and to what extent samples from the plume are representative of ocean composition. Previous models to predict this behavior mostly relied on boiling of water as the primary way that gas and droplets are ejected, but these models do not take into account all of the physics involved, and do not fully reproduce what Cassini observed at Enceladus. We propose a new model that instead invokes dissolved gas molecules expanding, similar to explosive volcanoes on Earth and essentially the same mechanism that causes cans of soda to explode upon opening if shaken. We predict that the erupting jets would largely preserve bulk ocean content and thus would be the best place to study ocean content, in contrast with the broader plume, which would have more water that has sublimated from the surface. Key Points: Recent studies on the ascent and eruption of Enceladus' plume have neglected the role of exsolution and expansion of dissolved volatilesVolatile‐driven direct ocean‐to‐jet liquid water ascent is generally consistent with observations if combined with a sublimation co‐plumeThis mode of ascent could preserve ocean bulk content in jets, leading to jet sampling strategies being preferred for future missions [ABSTRACT FROM AUTHOR]

There are various hotspots in the Atlantic Ocean, which are underlain by mantle plumes that likely cross the mantle and originate at the core‐mantle boundary. We use teleseismic core‐diffracted shear waves to look for an Ultra‐Low Velocity Zone (ULVZ) at the potential base of central Atlantic mantle plumes. Our data set shows delayed postcursory phases after the core‐diffracted shear waves. The observed patterns are consistent in frequency dependence, delay time, and scatter pattern with those caused by mega‐ULVZs previously modeled elsewhere. Synthetic modeling of a cylindrical structure on the core‐mantle boundary below St. Helena provides a good fit to the data. The preferred model is 600 km across and 20 km high, centered at approximately 15° South, 15° West, and with a 30% S‐wave velocity reduction. Significant uncertainties and trade‐offs do remain to these parameters, but a large ULVZ is needed to explain the data. The location is west of St. Helena and south of Ascension. Helium and neon isotopic systematics observed in samples from this region could point to a less‐outgassed mantle component mixed in with the dominant signature of recycled material. These observations could be explained by a contribution from the Large Low Shear Velocity Province (LLSVP). Tungsten isotopic measurements would be needed to understand whether a contribution from the mega‐ULVZ is also required at St. Helena or Ascension. Plain Language Summary: Nearly 3,000 km beneath the Atlantic to the West of the island of St. Helena, on the boundary between Earth's metal core and rocky mantle, we have discovered a new area where seismic waves diffracting along that boundary travel significantly slower than expected. This area is called an ultra‐low velocity zone. In this study, we use seismic waves which propagate along the core‐mantle boundary. The waves that interact with the ultra‐low velocity zone are scattered and become severely delayed. Using the observations, we have constrained the ultra‐low velocity zone to a broadly cylindrical structure, 600 km across, 20 km high and centered at 15° South, 15° West. The material inside is reduced by 30% in seismic shear wave velocity compared to outside. We confirmed this model by computing and comparing synthetic waveforms for a range of different ultra‐low velocity zone models. This ULVZ location is right beside or just inside a much larger region of low velocity, dubbed the African Large Low Shear‐Velocity Province (LLSVP). The observed ultra‐low velocity zone could be the base of the upwelling or mantle plume rising through the mantle and causing the hotspots of St. Helena and/or Ascension at the surface. Key Points: Observation of significant Sdiff postcursors sampling the CMB beneath the AtlanticModeling of postcursors reveals a previously unknown mega‐ULVZ situated on the CMB to the West of St. HelenaFurther measurements of St. Helena and Ascension samples are needed to identify a potential ULVZ‐associated geochemical signature [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) is an additive manufacturing technology with high practical value. In order to improve the quality of the fabricated parts, process monitoring has become a crucial solution, offering the potential to ensure manufacturing stability and repeatability. However, a cardinal challenge involves discerning a precise correlation between process characteristics and potential defects. This paper elucidates the integration of an off-axis vision monitoring mechanism via a high-speed camera focused on capturing the single-track melting phenomenon. An innovative image processing method was devised to segment the plume and spatters, while Kalman filter was employed for multi-object tracking of the spatters. The features of both the plume and spatters were extracted, and their relationship with molten states was investigated. Finally, the PSO-XGBoost algorithm was utilized to identify five molten states, achieving an accuracy of 92.16%. The novelty of this approach resides in its unique combination of plume characteristics, spatter features, and computationally efficient machine learning models, which collectively address the challenge of limited field of view prevalent in real production scenarios, thereby enhancing process monitoring efficacy. Relative to existing methodologies, the proposed PSO-XGBoost approach offers heightened accuracy, convenience, and appropriateness for the monitoring of the LPBF process. This work provides an effective and novel approach to monitor the LPBF process and evaluate the part fabrication quality for complex and changeable working conditions. [ABSTRACT FROM AUTHOR]

In 2021, more than 50 paroxysmal episodes occurred at the South-East Crater (SEC) of Mt Etna, Italy. The 23–24 March lava fountain was one of the longest episodes and began with weak Strombolian explosions, gradually transitioning to lava fountaining. The eruption intensity then dropped more slowly than in previous episodes, resulting in pulsating Strombolian explosions dominated by ash emission. Thirty-four tephra samples were used to reconstruct the fallout dispersal and estimate the total erupted mass. Grain size, textural, petrological and geochemical analyses indicate different features and were compared with the gas phase (SO2 and HCl) in the volcanic plume. By applying stochastic global optimization to simulations of the temporal evolution of the eruption column height and tephra dispersal and deposition, the total erupted mass retrieved (6.76 × 108 kg) matches well the total erupted mass estimation by the ground-based deposit (8.03 ± 2.38 × 108 kg), reducing the column height throughout the episode from 6.44 to 4.5 km above sea level and resulting in a mass eruption rate ranging from 1.96 × 105 to 8.18 × 103 kg/s. The unusual duration of the March episode and the characteristics of the erupted products point to the change in explosive style and magma fragmentation from fountaining to ash emission phases, associated with a slower magma supply inducing a change in magma rheology and a final, prolonged ash generation. Furthermore, this study showed that using observational data and the variation in eruption source parameters for numerical simulations can improve the accuracy of predicting the dispersal plume, thus mitigating the potential impact of longer paroxysmal episodes. [ABSTRACT FROM AUTHOR]

Quaternary rocks from the East and West Eifel volcanic fields in western Germany are a key suite of intraplate volcanic rocks that can provide insights into volcanism of the Central European Volcanic Province (CEVP) and into continental intraplate volcanism in general. We present a comprehensive dataset for Eifel lavas including isotope as well as major and trace element data for 59 samples covering representative compositions of the different volcanic fields. In line with previous studies, the lavas are all SiO2-undersaturated, alkaline-rich and mainly comprise primitive basanites, melilitites, and nephelinites (Mg# ≥ 57). Geochemical compositions of samples from both volcanic subfields display distinct differences in their trace-element as well as radiogenic isotope compositions, largely confirming previous subdivisions. Coupled trace-element and radiogenic Sr–Nd–Hf–Pb–Os isotope compositions can now provide firm evidence for spatially heterogeneous mantle sources and compositionally distinct magmatic pulses. Within the West Eifel Field, Sr–Nd–Pb isotope compositions of the younger (≤80 ka), ONB-suite (olivine-nephelinite-basanite) are similar to FOZO (FOcal ZOne) or the EAR (European Asthenospheric Reservoir) and resemble compositions that have been previously reported from plume-sourced ocean island basalts (OIB). In marked difference, older (700 Ma to 80 ka) volcanic rocks from the F-suite (Foidite) in the West Eifel field and from the entire east Eifel Field tap a more enriched mantle component, as illustrated by more radiogenic Sr isotope (86Sr/87Sr up to 0.705408) and variable Pb isotope compositions (206Pb/204Pb = 18.61–19.70, 207Pb/204Pb = 15.62–15.67 and 208Pb/204Pb = 38.89–39.76). Combined trace-element compositions of ONB-suite samples are in good agreement with results from batch melting models suggesting a hybrid composition of Eifel magmas formed through mixing 10% of a FOZO-like melt with 90% of a DMM-like melt, similar to melts from the Tertiary HEVF. However, radiogenic Sr–Nd–Pb isotope compositions of F-suite and EEVF and some ONB lavas require the admixture of melts from lithospheric mantle sources. Elevated Nb/Ta and Lu/Hf ratios in combination with variable 187Os/188Os ratios can now demonstrate the presence of residual carbonated eclogite components, either in the lithosphere or in the asthenospheric mantle. Finally, by combining geochemical and temporal constraints of Tertiary and Quaternary volcanism it becomes evident that CEVP volcanism in central and western Germany has resulted from compositionally distinct magmatic pulses that tap separate mantle sources. Although the presence of a mantle plume can neither be fully confirmed nor excluded, plume-like melt pulses which partially tap carbonated eclogite domains that interact to variable extents with the lithosphere provide a viable explanation for the temporal and compositional cyclicity of CEVP volcanism. [ABSTRACT FROM AUTHOR]

X‐band marine radar observations and a hindcast simulation from a 3D hydrostatic model are used to provide an overview of Connecticut River (USA) ebb plume front expansion into the strong tidal crossflow of eastern Long Island Sound. The model performance is evaluated against in situ and remote sensing observations and demonstrates dominant control of the front by semidiurnal tides. The recurring frontal evolution is classified into three dynamical stages of arrest, propagation, and advection. A conceptual model that follows this progressing balance between outflow buoyancy and crossflow momentum qualitatively reproduces frontal evolution in both the radar observations and the hindcast. The majority of the residual, intertidal variability of front timing and geometry is explained by co‐varying tidal amplitude, freshwater discharge, and wind stress using a multi‐linear regression analysis of the radar observation record. Intrinsic front speeds in the modeled frontal propagation are compared with the analytical model of Benjamin (1968, https://doi.org/10.1017/s0022112068000133), with better agreement achieved after accounting for ambient near‐surface shear associated with wind forcing. Plain Language Summary: The fresh buoyant water that exits the Connecticut River mouth (USA) during each ebb tide expands as a plume, and floats above the denser waters of Long Island Sound. Currents in the Sound flow back and forth along the coast each tide, pushing the plume along the shore first to the east and then to the west. The location of the plume boundary (front) goes through a similar cycle almost every tide, initially being held stationary by eastward tidal currents, then expanding freely around slack tide, and subsequently being aided as it moves to the west by the ambient flow. Small changes to the arrival time and shape of the front are linked to changes in river discharge, tidal strength, and winds. Realistic simulations using a type of numerical model that aids coastal decision making are able to reproduce the tidal progression of front movement that was observed in 6 weeks of marine radar images of the water surface. Front movement in the numerical model also fits a simple analytical theory to a degree not previously seen on such a large scale, despite the complicating effects of wind. Key Points: Buoyant ebb plume front kinematics in a tidal cross‐flow are characterized by stages of arrest, propagation, and advectionWind, tide, and discharge variations explain modifications to the dominant semidiurnal control of the Connecticut River plume frontFront propagation in a hydrostatic numerical model reproduces both radar remote sensing observations and gravity current theory [ABSTRACT FROM AUTHOR]

Hydrothermal vents emit hot fluids enriched in energy sources for microbial life. Here, we compare the ecological and biogeochemical effects of hydrothermal venting of two recently discovered volcanic seamounts, Polaris and Aurora of the Gakkel Ridge, in the ice-covered Central Arctic Ocean. At both sites, persistent hydrothermal plumes increased up to 800 m into the deep Arctic Ocean. In the two non-buoyant plumes, rates of microbial carbon fixation were strongly elevated compared to background values of 0.5–1 μmol m−3 day−1 in the Arctic deep water, which suggests increased chemoautotrophy on vent-derived energy sources. In the Polaris plume, free sulfide and up to 360 nM hydrogen enabled microorganisms to fix up to 46 μmol inorganic carbon (IC) m−3 day−1. This energy pulse resulted in a strong increase in the relative abundance of SUP05 by 25% and Candidatus Sulfurimonas pluma by 7% of all bacteria. At Aurora, microorganisms fixed up to 35 μmol IC m−3 day−1. Here, metal sulfides limited the bioavailability of reduced sulfur species, and the putative hydrogen oxidizer Ca. S. pluma constituted 35% and SUP05 10% of all bacteria. In accordance with this data, transcriptomic analysis showed a high enrichment of hydrogenase-coding transcripts in Aurora and an enrichment of transcripts coding for sulfur oxidation in Polaris. There was neither evidence for methane consumption nor a substantial increase in the abundance of putative methanotrophs or their transcripts in either plume. Together, our results demonstrate the dominance of hydrogen and sulfide as energy sources in Arctic hydrothermal vent plumes.

The study provides novel and valuable insights into the behavior of fluid flow and heat transfer in a generated plume under the influence of an aligned magnetic field, which is a complex and less-explored area in fluid dynamics. Incorporating variable viscosity and suction effects adds to the realism and applicability of the model, as it accounts for more realistic conditions where fluid properties change with temperature and external forces influence the flow. A mathematical model is formulated as a system of coupled partial differential equations to analyze the flow dynamics. Subsequently, a numerical solution is derived with stream function formulation for the system of coupled partial differential equations, which transmuted it into ordinary differential equations. To achieve this, the numerical properties of the problem are established through the utilization of a Shooting method in tandem with the MATLAB tool bvp4c. The graphical representations of both missing and specified boundary conditions, analyzes the influences of the viscosity parameter ε, suction parameter ξ, magnetic force parameter S, Prandtl number Pr and magnetic Prandtl number γ. The impact of these parameters on the heat transfer and fluid flow is given in detail. Inclusion of suction velocity counteracted the effects of temperature-dependent viscosity. The velocity f′, current density ϕ″, temperature θ, skin friction f″ and magnetic flux ϕ′ depicted an enhanced behavior while heat transfer rate θ′ dropped with an increment in viscosity parameter ε. However, for an increasing suction parameter ξ, the reverse trend of these properties is observed as compared to the viscosity parameter ε. The inclusion of suction counteracted to the effects of variable viscosity. Understanding how heat plumes behave under magnetic fields the study aims to provide insights that can be applied to real-world scenarios, such as improving cooling systems in industrial applications, enhancing environmental safety measures, and optimizing biomedical engineering processes.

The article presents a study of the Earth’s crust and upper mantle in the Pechenga ore region, as well as areas adjacent to it in the northwestern part of the Kola region. Applying the receiver function technique to data acquired by three broadband seismic stations, we obtained one-dimensional seismic velocity distribution models to a depth of 300 km. The stations are located in the northern parts of Finland and Norway, as well as in the Pechenga region of the Russian Federation. Despite the stations being in relatively close proximity (within 100 km of each other), the velocity models turned out to be significantly different, which indicates structural discontinuity within the lithosphere. Thus, Finland station data set revealed a gradient crust-mantle transition, which is not present in the other two models. At depths of about 150 km, a low-velocity zone was discovered, associated with mid-lithospheric discontinuity, which was not found beneath the Pechenga ore region. Furthermore, the crustal structure of the Pechenga region has an anomalously high Vp/Vs ratio to a depth of about 20 km. Considering the fact that the Pechenga (Nikel) seismic station was installed in close proximity to major copper-nickel deposits, this anomaly can be interpreted as a relic of Proterozoic plume activity.

Paleomagnetic dating of the Bolshesyrsky igneous area, a thick intraplate igneous complex of Khakassia, was carried out. The complex has not been dated due to the peculiarities of the stratigraphy and the lack of suitable rocks for applying the methods of absolute geochronology. The use of the paleomagnetic method has shown that the paleomagnetic pole of the red beds, which are intruded by sills and dikes of the Bolshesyrsky area, is close to the Silurian paleomagnetic poles of Siberia and Tuva and differs sharply from the Ordovician paleomagnetic poles of these areas. That is, red-colored rocks are Silurian, and subvolcanic rocks are post-Silurian. The sharp unconformable overlapping of the red-colored and volcanic strata with the Middle Devonian sedimentary trough without igneous rocks indicates that the age of the Bolshesyrsky complex is limited to the Silurian-Early Devonian interval. The genesis of the rocks of the Bolshesyrsky magmatic area was associated with the activity of the Early Devonian Minusinsk plume.

AbstractThis present research concerns with the study of two-dimensional, steady, magnetohydrodynamic free convection flow in a plume generated due to horizontal line heat source. The aligned magnetic field is applied at the vertical component of plume. The mathematical model of the governing flow problem is based on coupled nonlinear partial differential equations. Later, the system of partial differential equations is transformed into system of ordinary differential equations by using appropriate form of stream function formulation. For computational results, a Shooting technique along with bvp4c algorithm for MATLAB is employed to estimate the missing conditions in flow model. The effects of variation in Prandtl number., magnetic force parameter S, and magnetic Prandtl number γ on the velocity, current density, and temperature profile are illustrated in graphical manner along with their physical impacts. The novelty of current work is that the magnetic field has its strong impact on the vertical component of plume generated due to heat source. It is observed that, with the increase in the parameter S, the missing conditions, the velocity, current density, and temperature decreased. Whereas, the specified conditions, the skin friction f″ and magnetic flux ϕ′ drop while heat transfer rate θ′ enhanced with increment in parameter S. [ABSTRACT FROM AUTHOR]

Whistler mode waves in the plasmasphere and plumes drive significant losses of energetic electrons from the Earth's radiation belts into the upper atmosphere. In this study, we conducted a survey of amplitude‐dependent whistler wave properties and analyzed their associated background plasma conditions and electron fluxes in the plasmasphere and plumes. Our findings indicate that extremely large amplitude (>400 pT) whistler waves (a) tend to occur at L > 4 over the midnight‐dawn‐noon sectors and have small wave normal angles; (b) are more likely to occur during active geomagnetic conditions associated with higher fluxes of anisotropic electrons at 10 s keV energies; and (c) tend to occur at higher latitudes up to 20° with increasing amplitude. These results suggest that extremely large amplitude whistler waves in the plasmasphere and plumes could be generated locally by injected electrons during substorms and further amplified when propagating to higher latitudes. Plain Language Summary: Whistler mode waves are known as one of the primary drivers of precipitating energetic electrons from the Earth's radiation belts into the upper atmosphere. We utilize plasma wave observations from the Van Allen Probes mission and conduct a survey of whistler mode waves inside the plasmasphere and plumes, which are plasma regions surrounding the Earth and filled with high‐density cold electrons. Statistical results indicate that extremely large amplitude whistler waves are more likely to occur at large L shells (L shell is defined as the distance from magnetic field lines to the center of the Earth at the magnetic equator) in the post‐midnight sectors during active geomagnetic conditions associated with high fluxes of tens of keV electrons exhibiting anisotropic pitch angle distributions (with a flux peak in the direction that is perpendicular to the background magnetic field). These waves tend to occur at higher latitudes with increasing amplitude. Results suggest that these waves could be generated locally by injected electrons during substorm activity and may be further amplified when propagating to higher latitudes. Key Points: Van Allen Probes wave measurements are used to statistically analyze the whistler waves in the plasmasphere or plume regionsExtremely large amplitude (>400 pT) whistler waves tend to occur at L shells >4 over 0–18 hr MLT with small wave normal angles (<10°)Larger amplitude whistler waves are observed during more active substorm activities and higher magnetic latitudes [ABSTRACT FROM AUTHOR]

The process of separating stages is crucial for multistage rockets, directly influencing the success of the launch plan. Different separation timing methods alter the flow field structure within the interlevel zone at separation, influencing the separation of the two-stage rockets. This paper employs the SST k-ω turbulence model to investigate the structure of the flow field and its aerodynamic and motion characteristics under different nozzle baffle opening and separation times, taking into account variable properties, supersonic compressibility, and the upstream–downstream interference. First, we examined the standard flow field structure, considering the engine jet, the lateral jet between stages, and the disturbance from the external supersonic inflow. Then, we discussed the displacement characteristics and axial force coefficient curves of the first and second steps of the separation process. Finally, we explored the impact of baffle opening and separation times on the flow field structure and axial force coefficients of the two stages at the onset of separation. For the flow field structure, a delay in the baffle opening and separation moment led to a gradual increase in downstream and separation regions until they stabilized after a certain range. However, the axial force coefficients displayed different behavior before and after the design point. [ABSTRACT FROM AUTHOR]

The Beyşehir-Hoyran Nappes, one of the tectonostratigraphic units of the Taurides, are thought to be originated from the Izmir-Ankara Ocean (northern branch of Neotethys). In this study, Late Paleozoic rock units from the blocks of Beyşehir-Hoyran Nappes were studied in detail using foraminiferal assemblages in two different locations from the southwest of Karaman City (southern Turkey). In both places, blocks/slices and pebbles of various origins are embedded within a highly sheared matrix of Late Cretaceous Age, and the whole unit can be regarded as a sedimentary mélange. The ages of the blocks from the southwest of Karaman City range from the Late Serpukhovian (Late Mississippian) to Late Capitanian (Middle Permian) with some depositional breaks (e.g., Bashkirian, Kasimovian). Combined with the previous data from the Mersin Mélange, which also include the remnants of the Beyşehir-Hoyran Nappes, our new findings suggest that a shallowing-upward sequence, characterized by a shallow water environment with foraminifera-bearing limestones, was deposited over the Tournaisian pelagic sequence in the Beyşehir-Hoyran Nappes till the Early Moscovian (Early Middle Pennsylvanian). This shallowing-upward sequence in the Beyşehir-Hoyran Nappes could be related to the Late Paleozoic Glaciation on the Gondwana supercontinent (Glacial II), which resulted in a sea-level drop and deposition of platform carbonates during the Viséan–Early Moscovian (Middle Mississippian to Early Middle Pennsylvanian) time interval. The absence of the main part of the Middle-Upper Pennsylvanian deposits (continental phase during the Middle Moscovian–Middle Gzhelian) in the Beyşehir-Hoyran Nappes can be mainly attributed to the occurrence of a mantle plume and partially to the effect of Late Paleozoic Gondwanan Glaciation (Glacial III). Progressive uplifting by the buoyant mantle plume material has resulted in rifting at the center of the basin where the Beyşehir-Hoyran Nappes have deposited. The rifting process led to tectonic destabilization of the platform in the basin, causing accumulation of the Upper Gzhelian (uppermost Pennsylvanian) detrital limestone with broken and abraded foraminiferal shells. Following this, deep basinal conditions prevailed during the Late Asselian–Kungurian (Early Permian), as revealed in the Mersin Mélange, where radiolarian cherts are associated with continental within-plate lavas of extreme incompatible trace element enrichment. Similar processes were responsible for the continual deposition of detrital limestones in the same basin until the end of Late Capitanian (Middle Permian). Based on all these, the uplifting process followed by rift-related volcanic rocks and detrital limestones can be interpreted as the opening of the Izmir-Ankara Ocean (northern Neotethys). [ABSTRACT FROM AUTHOR]

Context. Microwave stub filters are widely used in radio engineering and telecommunication systems, as well as in technical information protection systems due to simplicity of design, possibility of realization in microstrip design and manufacturability in mass production. For synthesis of stub filters nowadays traditional methods based on transformation of low-frequency prototype filters on LC-elements into filtering structures on elements with distributed parameters are used. The transformations used are approximate and provide satisfactory results for narrowband stub filters. In this connection there is a necessity in development of direct synthesis methods for stub filters, excluding various approximations and providing obtaining of amplitude-frequency characteristics with optimal shape for any bandwidths. Objective. The purpose of the study is to develop a method for direct synthesis of stub band-pass filters and low-pass filters with Chebyshev amplitude-frequency response in the passband. Method. The procedure of direct synthesis includes the formulation of relations for filter functions of plume structures, selection of approximating functions of Chebyshev type for filter functions and formation of a system of nonlinear equations for calculation of parameters of filter elements. Results. A method for the direct synthesis of stub bandpass and lowpass filters with Chebyshev response is developed. Conclusions. Scientific novelty of the work consists in the development of a new method of direct synthesis of l stub filters. The method, in contrast to approximate traditional methods of synthesis of microwave filters, is exact, and the obtained solutions of synthesis problems are optimal. The experiments confirmed the performance of the proposed method and the optimality of the obtained solutions. Prospects for further research suggest adapting the method to the synthesis of filter structures with more complex resonators compared to stubs. [ABSTRACT FROM AUTHOR]

Purpose: Aero-engine exhaust plume length can be more than the aircraft length, making it easier to detect and track by infrared seeker. Aim of this study is to analyze the effect of free stream Mach number (M∞) on length of potential core of plume. Also, change in infrared (IR) signature of plume and aircraft surface with variation in elevation angle (θ) is examined. Design/methodology/approach: Convergent divergent (CD) nozzle is located outside the rear fuselage of the aircraft. A two dimensional axisymmetric computational fluid dynamics (CFD) study was carried out to study effect of M∞ on potential core. The CFD data with aircraft and plume was then used for IR signature analysis. The sensor position is changed with respect to aircraft from directly bottom towards frontal section of aircraft. The IR signature is studied in mid wave IR (MWIR) and long wave IR (LWIR) band. Findings: The potential plume core length and width increases as M∞ increases. At higher altitudes, the potential core length increases for a fixed M∞. The plume emits radiation in the MWIR band, whereas the aerodynamically heated aircraft surface emits IR in the LWIR band. The IR signature in the MWIR band continuously decreases as the sensor position changes from directly bottom towards frontal. In the LWIR band the IR signature initially decreases as the sensor moves from the directly bottom to the frontal, as the sensor begins to see the wing leading edges and nose cone, the IR signature in the LWIR band slightly increases. Originality/value: The novelty of this study comes from the data reported on the effect of free stream Mach number on the potential plume core and variation of the overall IR signature of aircraft with change in elevation angle from directly below towards frontal section of aircraft. [ABSTRACT FROM AUTHOR]

Abstract There are various hotspots in the Atlantic Ocean, which are underlain by mantle plumes that likely cross the mantle and originate at the core‐mantle boundary. We use teleseismic core‐diffracted shear waves to look for an Ultra‐Low Velocity Zone (ULVZ) at the potential base of central Atlantic mantle plumes. Our data set shows delayed postcursory phases after the core‐diffracted shear waves. The observed patterns are consistent in frequency dependence, delay time, and scatter pattern with those caused by mega‐ULVZs previously modeled elsewhere. Synthetic modeling of a cylindrical structure on the core‐mantle boundary below St. Helena provides a good fit to the data. The preferred model is 600 km across and 20 km high, centered at approximately 15° South, 15° West, and with a 30% S‐wave velocity reduction. Significant uncertainties and trade‐offs do remain to these parameters, but a large ULVZ is needed to explain the data. The location is west of St. Helena and south of Ascension. Helium and neon isotopic systematics observed in samples from this region could point to a less‐outgassed mantle component mixed in with the dominant signature of recycled material. These observations could be explained by a contribution from the Large Low Shear Velocity Province (LLSVP). Tungsten isotopic measurements would be needed to understand whether a contribution from the mega‐ULVZ is also required at St. Helena or Ascension.

Based on the data of long-term coastal and expeditionary observations, the structure and dynamics of transitional waters in the system of the Dnieper-Bug estuary (the DBE) before the destruction of the Kakhovka HPP are considered as the basis for the future description of changes in the hydrological regime. Average annual and seasonal maps and vertical sections of temperature and salinity are drafted. The article analyzes the main factors of formation and distribution of transitional waters such as river runoff, salinity (density) contrast and surface wind. A number of dimensional and dimensionless criteria and indicators of the transitional water dynamics within and outside the DBE are calculated and analyzed. The analysis of previous studies of river water transformation in the North-Western part of the Black Sea (NWBS) and dynamics of floating plumes in other areas of the World Ocean's coastal zone allows us to establish a 14 P.S.U. isohaline as the outer limit for transitional waters of the NWBS. According to the monitoring data of 1992-2020, the highest degree of desalination of the DBE and output of transition water from the Kinburn Strait was observed in spring, under the conditions of increasing volume of river runoff and predominant wind from the east. At the same time, the increasing repeatability of the south wind contributed to pushing the plume towards the coastal area outside the estuary. In summer, the influence of open sea waters on the DBE increased due to decreasing river runoff and increasing frequency of westerly winds. According to theoretical criteria, under low-wind conditions, the estuary produces a surface-advective plume affected by buoyancy and Coriolis force, with no effect of friction in the bottom boundary layer. The distance over which such plume spreads, even in summer, does not exceed half way from the Kinburn Strait to the Odesa Bay. The ingress thereto of transitional waters of the DBE in spring and autumn can be facilitated by accompanying wind currents. The main factor of the plume's summer dynamics includes both westerly wind and the currents it generates. The latter prevent the spread of transitional waters to the west along the coast, pushing them towards the estuary and to the south off it. This does not negate the possibility of a different plume behavior due to the increasing volume of river runoff and synoptic variability of the wind field during certain years and months.

The problem of hyperbasites origin is one of the widely discussed topics in geology. This is because they often appear when no expected. Their development does not correspond to the general regularities of the geological complexes’ development. Therefore, when problematic instances of hyperbasites appear, discussion is inevitable. This is due to the imperfections of existing concepts, which are not without flaws. The essence of this concept lies in the fact that during the rotation of the Earth around its axis, geodynamic forces are formed. The hyperbasites complex by its nature belongs to deep igneous formations formed at the initial stage of development of volcano-plutonic processes, where the composition of magmatic products was not subject to decomposition. In general, the origin of igneous rocks is associated with deep anomalous processes, which were formed under the influence of geodynamic forces, where decompression of mantle matter occurs, causing a catastrophic increase in the volume of mantle matter, as well as the associated development of volcanoplutonic processes. Hyperbasites are formed both in divergent and convergent zones of the Earth’s crust. The main factor for their formation is high pressure – deep thermodynamic conditions, where there are no favorable thermodynamic conditions for the complete separation of magmatic melts by composition. The emergence of hypermafic rocks on the surface is associated with geotectonic or denudation processes. Denudation processes can expose only those hypermafic formations that are located at the site of formation. These zones include ancient platforms, sheets, terranes, etc., which were cut by deep erosion processes. As for those hyperbasic formations that are classified as alpinotype hyperbasites, they were moved to the structure of the Alps-Himalayan folded zone from the basement with a collision with subsequent geotectonic processes, where they formed in the bed of the Paleotethys Ocean, both in the process of divergence and convergence. The noted pattern of formation and the mechanism of formation of alpine-type hyperbasites clearly corresponds to the patterns of development of geodynamic forces in the face of the Earth, also with natural laws, which are the main factors in the evolution of the Earth’s crust. From the standpoint of KDEZK, the origin, mechanism of formation, as well as the form of distribution of alpinotype hypermafic rocks of the Lesser Caucasus occurred in the Paleotethys bed, under different thermodynamic conditions and at depths. Further, as a result of the collision, it participated in the formation of folded zones of the Lesser Caucasus. Within the Lesser Caucasus, two genetic types of hypermafic rocks are exposed. Some of them correspond to the convergent zone of the Tethys paleocean, while others correspond to divergent zones. In terms of ore content, the most promising are those hypermafic rocks that are genetically related to convergent zones.

Rheological layering of the tectonosphere of the South China Sea (SCS) on the crust—rigid (the depth interval of 5–30 km), viscous subcrustal (the depth interval of 30–70 km), rigid lower lithospheric (50–90 km), astenospheric (80–150 km) and rigid subastenospheric (the depth interval is more than 150 km)—is established. Distributions of the density inhomogeneities related to the main tectonic events in the SCS are caused by the Paleo-Pacific's convergence, and later, the oceanic Philippine Plate, with the Philippine archipelago and later, with the Asian margin. In this zone, based on density contrast distributions in the tectonosphere, Cenozoic processes of a subduction, stretching, transform shift and structure of the central type of the probable plume nature are traced, which form an evolutionary sequence: back-arc, or paleoceanic spreading → Philippine subduction → NE-stretching with discplacement → formation of a central type of structure, probably with a plume origin. The structures caused by convergence of the Asian continent with the Indo-Australian Plate are isolated from the West Pacific margin, and underthrusting of rigid lithospheric plates from the south under the lithosphere of the marginal sea reflects traces of a more ancient collision of fragments of Gondwana with the Asian continent. [ABSTRACT FROM AUTHOR]

The interaction between aerosols and clouds is one of the major uncertainties in past climate change, affecting the accuracy of future climate projections. Ship tracks, trails left in clouds through the addition of aerosol in the ship exhaust plume, have become a key observational tool for constraining aerosol‐cloud interactions. However, many expected tracks remain undetected, presenting a significant gap in current knowledge of aerosol forcing. Here we leverage a plume‐parcel model to simulate the impact of aerosol dispersion for 2,957 cases off California's coast on cloud droplet number concentration (CDNC) enhancements. Plume‐parcel models show a large sensitivity to updraft uncertainties, which are found to be a primary control on track formation. Using these plume‐parcel models, updraft values consistent with observed CDNC enhancements are recovered, suggesting that relying solely on cloud‐top radiative cooling may overestimate in‐cloud updrafts by around 50%, hence overstating the cloud sensitivity to aerosols. Plain Language Summary: Here we investigate the interactions between aerosols and clouds and their impact on climate change. Ship tracks were used to study these interactions, and aerosol emissions from ships were modeled. It was shown that the increase in cloud droplets from ship aerosol was highly sensitive to the speed of the updraft in the clouds. A method was developed to fit the updraft to the observed cloud enhancements; the resultant updrafts were smaller than current estimates, suggesting that the clouds may be less sensitive to aerosols than previously thought. Key Points: Using ship emission data, a plume‐parcel model was implemented to study aerosol availability and cloud sensitivity in ship track formationCloud droplet number enhancements are very sensitive to uncertainties in the in‐cloud updraftThe retrieved plume‐parcel‐based updrafts suggest that clouds may be less sensitive to aerosols than implied by other estimates [ABSTRACT FROM AUTHOR]

Measurements of Sulak River plume parameters in the Caspian Sea conducted from June 2 to 7, 2023, concurrently with satellite survey allowed tracing changes in water turbidity (WT) and suspended particulate matter (SPM) concentration in the near-mouth zone after the arrival of mudflow masses into the sea. Heavy rains in the mountains of Dagestan on May 31, 2023, caused mudflows, which entered, in particular, the Sulak River. Two days later, on June 2, mud masses, together with river water, flowed into the Caspian Sea. In the near-mouth zone, WT values exceeded 1000 NTU, which was beyond the allowable threshold of a portable turbidimeter employed for turbidity measurements. On June 2, 4, 5 and 7, quasi-synchronously with satellite imaging, measurements were conducted from a small boat using various oceanographic equipment. They were accompanied with water sampling for further determination of SPM concentration and mineral composition. The linear dependence revealed between WT and SPM concentration made it possible to calculate WT that could not be measured in situ: it amounted to 1247 NTU at SPM concentration of 1097.4 g/m3. Satellite data were used to compile WT maps using the Dogliotti 2015 algorithm. The results of satellite observations and in situ measurements showed that, within 2 days, WT and SPM concentration at the nearest to the river mouth station dropped sixfold and continued to decrease to the average values for this area in early June. Determined by X-ray phase analysis, the mineral composition of suspended solids on the day of mudflow arrival into the sea was represented mainly by clay minerals, their content reaching 75%. Later, by June 7, the mineral composition returned to the average values and the content of clay minerals did not exceed 44%. [ABSTRACT FROM AUTHOR]

On 29 September 2022 Juno's low‐light sensitive Stellar Reference Unit (SRU) captured a high‐resolution (256–340 m/pixel) broadband (450–1,100 nm) visible image of Europa's icy surface during the first close flyby of the Jovian moon since Galileo's last encounter in 2000. Collected at a sub‐spacecraft altitude of 412 km while the surface was illuminated only by Jupiter‐shine (incidence angle: 48–51°), the SRU image reveals a 3 × 104 km2 region between ∼0°–6°N and 43.5°–51°W in remarkable detail at the highest resolution to date. Prior coverage by Galileo under high‐sun conditions at 1 km resolution led to the characterization of the terrain as ridged plains with undifferentiated linea. The SRU image reveals a much richer and more complex picture. Intricate networks of cross‐cutting ridges and lineated bands surround an intriguing 37 km (east‐west) by 67 km (north‐south) chaos feature with a concentric fracture system, depressed matrix margins, and low‐albedo materials potentially associated with brine infiltration. The morphology and local relief of the chaos feature are consistent with formation in the collapse of ice overlying a salt‐rich lens of subsurface water. Low‐albedo deposits, similar to features previously associated with hypothesized cryovolcanic plume activity, flank nearby ridges. The SRU's high‐resolution view of many types of features in a single image allows us to explore their regional context and greatly improve the geologic mapping of this part of Europa's surface. The image reveals several relatively youthful features in a potentially dynamic region, providing baselines for candidate locations that future missions can investigate for present day surface activity. Plain Language Summary: On 29 September 2022, the Juno spacecraft performed the first close flyby of Jupiter's icy moon Europa in generation. The low‐light sensitive Juno SRU navigation camera was used to photograph a part of the surface that was lit only by sunlight scattered off Jupiter, from a spacecraft‐to‐surface distance of 412 km. This innovative use of a high‐resolution star camera designed to detect dim stars produced Juno's highest resolution image of Europa, and provides the highest resolution coverage of the targeted region to date. The imaged area is revealed to be incredibly complex and rich with many different types of terrains and features. Dark stains that may be associated with plumes, and an area of ice shell disruption nicknamed "the Platypus," are compelling targets for future missions to investigate possible present day surface activity. Key Points: Juno's Stellar Reference Unit imaged Europa's surface at high resolution while it was illuminated by Jupiter‐shineThe image reveals a feature‐rich region between 0°–6°N and 43.5°–51°W with hints of relatively recent activityA young 37 km by 67 km chaos feature and some low‐albedo deposits adjacent to double ridges may be associated with subsurface liquid water [ABSTRACT FROM AUTHOR]

The problem of hyperbasites origin is one of the widely discussed topics in geology. This is because they often appear when no expected. Their development does not correspond to the general regularities of the geological complexes' development. Therefore, when problematic instances of hyperbasites appear, discussion is inevitable. This is due to the imperfections of existing concepts, which are not without flaws. The essence of this concept lies in the fact that during the rotation of the Earth around its axis, geodynamic forces are formed. The hyperbasites complex by its nature belongs to deep igneous formations formed at the initial stage of development of volcano-plutonic processes, where the composition of magmatic products was not subject to decomposition. In general, the origin of igneous rocks is associated with deep anomalous processes, which were formed under the influence of geodynamic forces, where decompression of mantle matter occurs, causing a catastrophic increase in the volume of mantle matter, as well as the associated development of volcanoplutonic processes. Hyperbasites are formed both in divergent and convergent zones of the Earth's crust. The main factor for their formation is high pressure - deep thermodynamic conditions, where there are no favorable thermodynamic conditions for the complete separation of magmatic melts by composition. The emergence of hypermafic rocks on the surface is associated with geotectonic or denudation processes. Denudation processes can expose only those hypermafic formations that are located at the site of formation. These zones include ancient platforms, sheets, terranes, etc., which were cut by deep erosion processes. As for those hyperbasic formations that are classified as alpinotype hyperbasites, they were moved to the structure of the Alps-Himalayan folded zone from the basement with a collision with subsequent geotectonic processes, where they formed in the bed of the Paleotethys Ocean, both in the process of divergence and convergence. The noted pattern of formation and the mechanism of formation of alpine-type hyperbasites clearly corresponds to the patterns of development of geodynamic forces in the face of the Earth, also with natural laws, which are the main factors in the evolution of the Earth's crust. From the standpoint of KDEZK, the origin, mechanism of formation, as well as the form of distribution of alpinotype hypermafic rocks of the Lesser Caucasus occurred in the Paleotethys bed, under different thermodynamic conditions and at depths. Further, as a result of the collision, it participated in the formation of folded zones of the Lesser Caucasus. Within the Lesser Caucasus, two genetic types of hypermafic rocks are exposed. Some of them correspond to the convergent zone of the Tethys paleocean, while others correspond to divergent zones. In terms of ore content, the most promising are those hypermafic rocks that are genetically related to convergent zones. [ABSTRACT FROM AUTHOR]

Abstract Whistler mode waves in the plasmasphere and plumes drive significant losses of energetic electrons from the Earth's radiation belts into the upper atmosphere. In this study, we conducted a survey of amplitude‐dependent whistler wave properties and analyzed their associated background plasma conditions and electron fluxes in the plasmasphere and plumes. Our findings indicate that extremely large amplitude (>400 pT) whistler waves (a) tend to occur at L > 4 over the midnight‐dawn‐noon sectors and have small wave normal angles; (b) are more likely to occur during active geomagnetic conditions associated with higher fluxes of anisotropic electrons at 10 s keV energies; and (c) tend to occur at higher latitudes up to 20° with increasing amplitude. These results suggest that extremely large amplitude whistler waves in the plasmasphere and plumes could be generated locally by injected electrons during substorms and further amplified when propagating to higher latitudes.

In order to survive, animals often need to navigate a complex odor landscape where odors can exist in airborne plumes. Several odor plume properties change with distance from the odor source, providing potential navigational cues to searching animals. Here, we focus on odor intermittency, a temporal odor plume property that measures the fraction of time odor is above a threshold at a given point within the plume and decreases with increasing distance from the odor source. We sought to determine if mice can use changes in intermittency to locate an odor source. To do so, we trained mice on an intermittency discrimination task. We establish that mice can discriminate odor plume samples of low and high intermittency and that the neural responses in the olfactory bulb can account for task performance and support intermittency encoding. Modulation of sniffing, a behavioral parameter that is highly dynamic during odor-guided navigation, affects both behavioral outcome on the intermittency discrimination task and neural representation of intermittency. Together, this work demonstrates that intermittency is an odor plume property that can inform olfactory search and more broadly supports the notion that mammalian odor-based navigation can be guided by temporal odor plume properties.

Video cameras provide vital information on volcanic plumes from explosive eruptions, such as plume height, for monitoring and research. These images must be calibrated to get accurate quantitative data. However, the presence of wind complicates any calibration as the plume may no longer lie in the image plane, i.e. a plane perpendicular to the camera’s line-of-sight. Here, we present a simple new tool to correct for the effect of wind on the position and height of a volcanic plume as determined from imagery by rotating the image plane to be in the direction of the wind. We show the importance of accounting for the effect of wind on the maximum plume height determined from videos for two case-studies; a Vulcanian explosion from Sabancaya volcano, Peru, and a sustained plume from Mount Etna, Italy. This tool can improve the accuracy of quantitative information extracted from images of volcanic plumes, and should prove useful for both research and monitoring purposes.

Abstract The interaction between aerosols and clouds is one of the major uncertainties in past climate change, affecting the accuracy of future climate projections. Ship tracks, trails left in clouds through the addition of aerosol in the ship exhaust plume, have become a key observational tool for constraining aerosol‐cloud interactions. However, many expected tracks remain undetected, presenting a significant gap in current knowledge of aerosol forcing. Here we leverage a plume‐parcel model to simulate the impact of aerosol dispersion for 2,957 cases off California's coast on cloud droplet number concentration (CDNC) enhancements. Plume‐parcel models show a large sensitivity to updraft uncertainties, which are found to be a primary control on track formation. Using these plume‐parcel models, updraft values consistent with observed CDNC enhancements are recovered, suggesting that relying solely on cloud‐top radiative cooling may overestimate in‐cloud updrafts by around 50%, hence overstating the cloud sensitivity to aerosols.

New models of the deep velocity structure of the crust and upper mantle are presented for the Khibiny–Lovozero tectonic cluster located in the Kola Peninsula. The artifacts of plume-lithospheric interactions, which evolved in the region from the Proterozoic to the Paleozoic, are discussed. The velocity structure of the Imandra–Varzuga rift structure, the Khibiny and Lovozero intrusions, and the adjacent Archean part of the Fennoscandian Shield is compared in detail. A significant discontinuity of the crustal and upper mantle structure, as well as the structure and the depth of the crustal–mantle transition, is shown. The presence of a zone of lower seismic velocities in the upper mantle related to the mid-lithospheric discontinuity is revealed. The peculiarities of the structure of the Moho discontinuity and the upper mantle in the area of the Khibiny and Lovozero intrusions are interpreted for the first time as artifacts of the plume process. [ABSTRACT FROM AUTHOR]

This paper presents a calculation method and algorithm, as well as numerical results of studying chemically reacting turbulent jets based on three-dimensional parabolic systems of Navier–Stokes equations for multicomponent gas mixtures. Continuity equations are used to calculate the mass imbalance when solving with constant pressure, and with variable pressures, with the equations of motion and continuity. Diffusion combustion of a propane–butane mixture flowing from a square-shaped nozzle in a submerged flow of an air oxidizer is numerically studied. Pressure variability significantly affects the velocity (temperature) profiles in the initial sections of the jet, and, when moving away from the nozzle exit, the pressure effect can be considered imperceptible, but the plume length is longer than that at constant pressure, but it does not significantly affect the shape of the plume. The saddle-shaped behavior of the longitudinal velocity in the direction of the major axis is numerically obtained for large initial values of the turbulence kinetic energy of the main jet. The presented method allows studying nonreacting and reactive turbulent jets flowing from a rectangular nozzle. [ABSTRACT FROM AUTHOR]

Driving wind and slope of terrain can increase the rate of surface fire propagation. Previous physical modelling under higher driving wind (3–12.5 m/s) on slopes (Innocent et al., IJWF, 2023, 32(4), pp. 496–512 and 513–530) demonstrated that the averaged rate of fire spread (RoS) varied from that of empirical models. This study investigates the potential for better agreement at lower wind velocities (0.1 and 1 m/s), since empirical models are typically developed from experimental studies conducted under benign wind conditions. The same physical model WFDS is used. The results are analysed to understand the behaviour of various parameters (RoS, fire isochrone progression, fire intensity, flame dynamics, and heat fluxes) across different slopes. The RoS–slope angle relationship closely fits an exponential model, aligning with the findings from most experimental studies. The relative RoSs are aligned more closely with the Australian and Rothermel models' slope corrections for 0.1 and 1 m/s, respectively. The relationship between flame length and fire intensity matches predictions from an empirical power–law correlation. Flame and plume dynamics reveal that the plume rises at a short distance from the ignition line and fire propagation is primarily buoyancy-driven. The Byram number analysis shows buoyancy-dominated fire propagation at these lower wind velocities. Convective heat fluxes are found to be more significant at greater upslopes. The study confirmed that "lighter & drier" fuel parameters accelerated the fire front movement, increasing the RoS by approximately 57–60% compared to the original parameters. Overall, this study underscores the nuanced interplay of wind speed, slope, and other factors in influencing grassfire behaviour, providing valuable insights for predictive modelling and firefighting strategies. [ABSTRACT FROM AUTHOR]