Search NASA⌕ Search

SEARCH · Search NASA

Results for “Eruption dynamics”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Numerical simulations of solar disturbances and their interplanetary consequences

Time-dependent MHD numerical simulations are used to study responses of the solar atmosphere and interplanetary medium to simulated solar disturbances. A number of 2D and 3D examples of coronal mass ejection (CME) simulations and some current controversies concerning the basic processes of CME initiation are discussed. Footpoint shearing motion is tested to determine whether it can provide a reasonable mechanism for CME development from arch filament configurations. Possible interplanetary consequences to CME-like disturbances are demonstrated by using 3D simulations to determine the dynamic response of the solar wind to a plasmoid injection from an eruptive filament or prominence. The possibility that a plasmoid may be generated in the interplanetary medium by a solar-generated shock that propagates through a heliospheric current sheet is discussed. Application of the 3D model for the interpretation of interplanetary scintillation observations is addressed.

Dryer, M.↗
NASA NTRS2014

Trigger of Standard and Blowout Solar Jets: I. Parametric Studies of the Magnetic Field Geometry

Context. Jets are dynamic, impulsive, well collimated plasma events developing at many different scales and in differentlayers of the solar atmosphere.Aims. Jets are believed to be induced by magnetic reconnection a process central to many astrophysical phenomena.Studying their dynamics can help us to better understand the processes acting in larger eruptive events (e.g. flares andcoronal mass ejection) as well as mass, magnetic helicity and energy transfer at all scale in the solar atmosphere. Therelative simplicity of their magnetic geometry and topology, compared with larger solar active events, makes jets idealcandidate for studying the fundamental role of reconnection in energetic events. Methods. In this study, using our state-of-the-art numerical solver ARMS, we present several parametric studies of anumerical three-dimensional magneto-hydrodynamic model of solar jet-like events. We study the impact of the magneticfield inclination and photospheric field distribution on the generation and properties of two types of observed solar jets:the so-called standard and blowout jets.Results. The present parametric studies validate our model of jets for different geometric properties of the magneticconfiguration. On one hand, a blowout jets is eventually always trigger for the range of parameters that we tested. The3D magnetic null-point configuration is a very robust structure for the energy storage and impulsive release characteristicof blowout jets. On the other hand, the existence of the standard jet depends on the magnetic geometry. We show thatthe reconnection occurring during the standard jet phase influences the properties of the trigger of the blowout jet.Conclusions. Our results allow us to better understand the energization, triggering and driving processes of standardand blowout jets. Our model allows us to predict the impulsiveness and energetics of jets in terms of the surroundingmagnetic field configuration. Finally we discuss the interpretation of standard jets and blowout jets and the physicalfactors that determine which type of jets will occur.

Pariat, E.↗
NASA NTRS2019

Volcanic Eruption Signatures in the Isotope Enabled Last Millennium Ensemble

Explosive volcanic eruptions are one of the largest natural climate perturbations, but few observational constraints exist on either the climate responses to eruptions or the properties (size, hemispheric aerosol distribution, etc.) of the eruptions themselves. Paleoclimate records are thus important sources of information on past eruptions, often through the measurement of oxygen isotopic ratios (𝛿18O) in natural archives. However, since many processes affect 𝛿18O, the dynamical interpretation of these records can be quite complex. Here we present results from new, isotope-enabled members of the Community Earth System Model Last Millennium Ensemble, documenting eruption-induced 𝛿18O variations throughout the climate system. Eruptions create significant perturbations in the 𝛿18O of precipitation and soil moisture in central/eastern North America, via excitation of the Atlantic Multidecadal Oscillation. Monsoon Asia and Australia also exhibit strong precipitation and soil 𝛿18O anomalies; in these cases, 𝛿18O may reflect changes to El Niño-Southern Oscillation phase following eruptions. Salinity and seawater 𝛿18O patterns demonstrate the importance of both local hydrologic shifts and the phasing of the El Niño-Southern Oscillation response, both along the equator and in the subtropics. In all cases, the responses are highly sensitive to eruption latitude, which points to the utility of isotopic records in constraining aerosol distribution patterns associated with past eruptions. This is most effective using precipitation 𝛿18O; all Southern eruptions and the majority (66%) of Northern eruptions can be correctly identified. This work thus serves as a starting point for new, quantitative uses of isotopic records for understanding volcanic impacts on climate.

Stevenson, S.↗
NASA NTRS2017

Prominence Eruption Initiated by Helical Kink Instability of an Embedded Flux Rope

We study the triggering mechanism of a limb-prominence eruption and the associated coronal mass ejection (CME) near AR 12342 using Solar Dynamics Observatory and Large Angle and Spectrometric Coronagraph/Solar Heliospheric Observatory observations. The prominence is seen with an embedded flux thread (FT) at one end and bifurcates from the middle to a different footpoint location. The morphological evolution of the FT is similar to that of an unstable flux rope (FR), which we regard as a prominence-embedded FR. The FR twist exceeds the critical value. In addition, the morphology of the prominence plasma in 304 Å images marks the helical nature of the magnetic skeleton, with a total of 2.96 turns along arc length. The potential field extrapolation model indicates that the critical height of the background magnetic field gradient falls within the inner corona (105 Mm), which is consistent with the extent of coronal plasma loops. These results suggest that the helical kink instability in the embedded FR caused the slow rise of the prominence to the height of the torus instability domain. Moreover, the differential emission measure analysis unveils heating of the prominence plasma to coronal temperatures during an eruption, suggesting reconnection-related heating underneath the upward rising embedded FR. The prominence starts with a slow rise motion of 10 km s(exp. -1), which is followed by fast and slow acceleration phases that have an average acceleration of 28.9 m s(exp. -2) and 2.4 m s(exp. -2) in C2 and C3 field of view, respectively. As predicted by previous numerical simulations, the observed synchronous kinematic profiles of the CME leading edge and the core support the involved FR instability in the prominence initiation.

Vemareddy, P.↗
NASA NTRS1992

Departure solutions of the unsteady thin-layer and full Navier-Stokes equations solved using streamline curvature based iteration techniques

The development of a thorough understanding of the mechanisms for vortex eruptions from viscous layers, which are believed to be associated with phenomena such as dynamic stall onset and transition, is crucial if accurate models of such phenomena are to be formulated. The development of such models may, in turn, allow for the possibility that such effects could be accounted for during the design of various aerodynamic devices such as wings, helicopter rotors, and turbomachinery blading and thus lead to designs which are stall free or stall resistant and which have better stall-recovery properties. The present investigation is being conducted as part of an effort to develop analytical and numerical tools which can be used to help improve our understanding of the vortex-eruption mechanism at high Reynolds numbers. The addition of the normal-momentum equation to the classical unsteady boundary-layer equations is crucial according to recent asymptotic analyses of the vortex-eruption problem and is a key feature of the analyses being developed by the present authors. The purpose of this paper is as follows: to describe departure solution behavior observed when using unsteady, streamline-curvature based solution procedures in which nontrivial transverse pressure gradient effects are included; and to show that special treatment of the time-derivative of the normal velocity is needed to eliminate the ill-posed solution behavior, which is observed when small spatial and temporal step sizes are used.

Barnett, M.↗
NASA NTRS2020

The Role of the SO2 Radiative Effect in Sustaining the Volcanic Winter and Soothing the Toba Impact on Climate

Volcanic eruptions are an important climate driver. The impact of Pinatubo-sized eruptions has been observed and is well constrained. The magnitude and duration of volcanic winter effects after super-eruptions such as Toba remain disputed due to disagreement between the strong cooling predicted by models, and much milder climate perturbations according to the paleo data. Here we present a re-evaluated climate impact of a Toba-sized super-eruption based on up-to-date GISS ModelE simulations. In this study, we account for all known primary mechanisms that govern the evolution of the volcanic plume and their nonlinear interactions. The SO2 radiative effects are evaluated for the first time in coupled climate simulations with the interactive atmospheric chemistry module. We found that SO2 effects on photochemistry, dynamics, and radiative forcing are especially prominent. Due to strong absorption in ultraviolet, SO2 feedback on photochemistry partially offsets the limiting effect associated with aerosol microphysical processes. SO2 greenhouse warming soothes the radiative cooling exerted by sulfate aerosols. SO2 absorption in the shortwave and longwave causes radiative heating and lofting of the volcanic plume, and boosts the efficiency of SO2 impact on photochemistry. Our analysis shows that SO2 lifetime and magnitude of effects scale up and increase with the amount of emitted material. For a Pinatubo-sized eruption, SO2 feedbacks on chemistry and dynamics are relevant only during the initial stage of the volcanic plume evolution, while local SO2 concentrations are high. For a Toba-sized eruption, SO2 effects are as important as sulfate aerosols, and produce a less extreme volcanic winter.

Sergey Osipov↗
NASA NTRS1994

Two-dimensional simulation of Pinatubo aerosol and its effect on stratospheric ozone

This paper presents time-dependent simulations of the response of the stratosphere to the injection into the atmosphere of massive amounts of sulfur during the eruption of Mt. Pinatubo (The Philippines) in June 1991. The study is based on a coupled two-dimensional chemical-dynamical-radiative model to which a microphysical model for sulfate aerosol formation and fate has been added. The study suggests that, during the first year (July 1991 to June 1992) following the volcanic eruption, the observed changes in the ozone amount integrated between 65 deg S and 65 deg N were caused primarily by changes in the meridional circulation (associated with heating by the volcanic cloud in the tropics) and in the photolysis rate of molecules such as ozone (associated with backscattering of light by the cloud). During the second year after the eruption, as the aerosol was dispersed at all latitudes and, in particular, reached the polar region, the largest contribution to ozone reduction resulted from the heterogeneous chemical conversion of N2O5 and ClONO2 on the surface of the aerosol particles. The conversion of the latter compound, and hence the magnitude of the calculated ozone depletion, is highly dependent on the temperature in the lower stratosphere. Despite the fact that the surface area provided by aerosol particles decreased during the second year following the eruption, the calculated ozone depletion remained significant because the conversion of N2O5 is insensitive to the aerosol surface area density for values larger than 1-10 sq microns/cu cm (depending on latitude). The predicted reduction in ozone at 20 km in March during the third year (July 1993 to June 1994) of the model integration is smaller by a factor of 2 than it was during the second year.

Tie, Xuexi↗
NASA NTRS1979

Dynamics of volcanic plumes on Io

Ballistic and aerodynamic models are proposed to explain the dynamics of the volcanic plumes on Io. A ballistic model, which assumes that eruptive gas and solid-particle flows become completely and permanently decoupled over a small distance as compared with the maximum particle height, is shown to be unable to account for the observed shape of Plume 3. An aerodynamic model which assumes the entrainment and transportation of solid particles by the gas flow into the central portion of the top of the plume, with ballistic particle trajectories only after passage through the first part of their descent, is then developed. The model accounts for plume shape by the formation of a weak decompression shock near the edge of the plume stalk, which constrains horizontal expansion until a sufficient altitude is reached. Calculated plume dimensions are then compared with observations of Ionian Plumes 1 and 3.

Cook, A. F.↗
NASA NTRS2011

Prominences: The Key to Understanding Solar Activity

Prominences are spectacular manifestations of both quiescent and eruptive solar activity. The largest examples can be seen with the naked eye during eclipses, making prominences among the first solar features to be described and catalogued. Steady improvements in temporal and spatial resolution from both ground- and space-based instruments have led us to recognize how complex and dynamic these majestic structures really are. Their distinguishing characteristics - cool knots and threads suspended in the hot corona, alignment along inversion lines in the photospheric magnetic field within highly sheared filament channels, and a tendency to disappear through eruption - offer vital clues as to their origin and dynamic evolution. Interpreting these clues has proven to be contentious, however, leading to fundamentally different models that address the basic questions: What is the magnetic structure supporting prominences, and how does so much cool, dense plasma appear in the corona? Despite centuries of increasingly detailed observations, the magnetic and plasma structures in prominences are poorly known. Routine measurements of the vector magnetic field in and around prominences have become possible only recently, while long-term monitoring of the underlying filament-channel formation process also remains scarce. The process responsible for prominence mass is equally difficult to establish, although we have long known that the chromosphere is the only plausible source. As I will discuss, however, the motions and locations of prominence material can be used to trace the coronal field, thus defining the magnetic origins of solar eruptions. A combination of observations, theory, and numerical modeling must be used to determine whether any of the competing theories accurately represents the physics of prominences. I will discuss the criteria for a successful prominence model, compare the leading models, and present in detail one promising, comprehensive scenario for prominence formation and evolution that could answer the two questions posed above.

Karpen, Judy T.↗
NASA NTRS2021

From Pseudostreamer Jets to Coronal Mass Ejections:: Observations of the Breakout Continuum

The magnetic breakout model, in which reconnection in the corona leads to destabilization of a filament channel, explains numerous features of eruptive solar events, from small-scale jets to global-scale coronal mass ejections (CMEs). The underlying multipolar topology, pre-eruption activities, and sequence of magnetic-reconnection onsets (first breakout, then flare) of many observed fast CMEs/eruptive flares are fully consistent with the model. Recently, we have demonstrated that most observed coronal-hole jets in fan/spine topologies also are induced by breakout reconnection at the null point above a filament channel (with or without a filament).For these two types of eruptions occurring in similar topologies, the key question is, why do some events generate jets while others form CMEs? We focused on the initiation of eruptions in large bright points/small active regions that were located in coronal holes and clearly exhibited null-point (fan/spine) topologies: such configurations are referred to as pseudostreamers. We analyzed and compared SDO/AIA,SOHO/LASCO, and RHESSI observations of three events. Our analysis of the events revealed two new observable signatures of breakout reconnection prior to the explosive jet/CME outflows and flare onset: coronal dimming and the opening-up of field lines above the breakout current sheet. Most key properties were similar among the selected erupting structures, thereby eliminating region size, photospheric field strength, magnetic configuration, and pre-eruptive evolution as discriminating factors between jets and CMEs. We consider the factors that contribute to the different types of dynamic behavior, and conclude that the determining factor is the ratio of the magnetic free energy associated with the filament channel compared to the energy associated with the overlying flux inside and outside the pseudostreamer dome. Our results imply that a pseudostreamer eruption must be fast in order to produce an interplanetary CME.

Sun↗
NASA NTRS2023

Plasmoids, Flows, and Jets During Magnetic Reconnection in a Failed Solar Eruption

We report a detailed analysis of a failed eruption and flare in active region 12018 on 2014 April 3 using multiwavelength observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly, IRIS, STEREO, and Hinode/Solar Optical Telescope. At least four jets were observed to emanate from the cusp of this small active region (large bright point) with a null-point topology during the 2 hr prior to the slow rise of a filament. During the filament slow rise multiple plasma blobs were seen, most likely formed in a null-point current sheet near the cusp. The subsequent filament eruption, which was outside the IRIS field of view, was accompanied by a flare but remained confined. During the explosive flare reconnection phase, additional blobs appeared repetitively and moved bidirectionally within the flaring region below the erupting filament. The filament kinked, rotated, and underwent leg–leg reconnection as it rose, yet it failed to produce a coronal mass ejection. Tiny jet-like features in the fan loops were detected during the filament slow rise/preflare phase. We interpret them as signatures of reconnection between the ambient magnetic field and the plasmoids leaving the null-point sheet and streaming along the fan loops. We contrast our interpretation of these tiny jets, which occur within the large-scale context of a failed filament eruption, with the local nanoflare-heating scenario proposed by Antolin et al.

Sun: jets↗
NASA NTRS2019

A CME-Producing Solar Eruption from the Interior of an Emerging Bipolar Active Region

In a negative-polarity coronal hole, magnetic flux emergence, seen by the Solar Dynamics Observatory's {SDO) Helioseismic Magnetic lmager (HMI), begins at approximately 19:00 UT on March 3, 2016. The emerged magnetic field produced sunspots, which NOAA numbered 12514 two days later. The emerging magnetic field is largely bipolar with the opposite-polarity fluxes spreading apart overall, but there is simultaneously some convergence and cancellation of opposite-polarity flux at the polarity inversion line (PIL) inside the emerging bipole. In the first fifteen hours after emergence onset, three obvious eruptions occur, observed in the coronal EUV images from SDO's Atmospheric Imaging Assembly (AIA). The first two erupt from separate segments of the external PIL between the emerging positve-polarity flux and the extant surrounding negative-polarity flux, with the exploding magnetic field being prepared and triggered by flux cancellation at the external PIL. The emerging bipole shows obvious overall left-handed shear and/or twist in its magnetic field. The focus of th is poster is the third and largest eruption, which comes from inside the emerging bipole and blows it open to produce a CME observed by SOHO/LASCO. That eruption is preceded by flux cancellation at the emerging bipole's interior PIL, cancellation that plausibly builds a sheared and twisted flux rope above the interior PIL and finally triggers the blow-out eruption of the flux rope via photospheric-convection•driven slow tether-cutting reconnection of the legs of the sheared core field, low above the interior PIL, as proposed by van Ballegooijen & Martens (1989) and Moore & Roumeliotis (1992). The production of this eruption is a (perhaps rare) counterexample to solar eruptions that result from external collisional shearing between opposite polarities from two distinct emerging and/or emerged bipoles (Chintzoglou et al. 2019).

Adams, M. L.↗
NASA NTRS1992

Circumnuclear pileups of dust and gas in M82

Red H-alpha and R-band CCD images of the M82 galaxy were obtained and compared with corresponding NIR S III forbidden-line and I-band images and with a smaller Br-gamma infrared-array image of the central 500 pc. Results furnish evidence of circumnuclear pileup in M82, probably toroidal in form, which is dynamically linked to the central (bilobal) starburst and which is now collimating the subsequent eruptions and emergent radiation.

Waller, William H.↗
NASA NTRS2019

IRIS Observations of Magnetic Interactions in the Solar Atmosphere Between Preexisting and Emerging Magnetic Fields. II. UV Emission Properties

Multiwavelength ultraviolet (UV) observations by the Interface Region Imaging Spectrograph satellite in active region NOAA 12529 have recently pointed out the presence of long-lasting brightenings, akin to UV bursts, and simultaneous plasma ejections occurring in the upper chromosphere and transition region during secondary flux emergence. These signatures have been interpreted as evidence of small-scale, recurrent magnetic reconnection episodes between the emerging flux region (EFR) and the preexisting plage field. Here we characterize the UV emission of these strong, intermittent brightenings and study the surge activity above the chromospheric arch filament system (AFS) overlying the EFR. We analyze the surges and the cospatial brightenings observed at different wavelengths. We find an asymmetry in the emission between the blue and red wings of the Si iv λ1402 Å and Mg ii k λ2796.3 lines, which clearly outlines the dynamics of the structures above the AFS that form during the small-scale eruptive phenomena. We also detect a correlation between the Doppler velocity and skewness of the Si iv λλ1394 and 1402 line profiles in the UV burst pixels. Finally, we show that genuine emission in the Fe xii λ1349.4 line is cospatial to the Si iv brightenings. This definitely reveals a pure coronal counterpart to the reconnection event.

Guglielmino, Salvo L.↗
NASA NTRS2019

A CME-Producing Solar Eruption from the Interior of a Twisted, Emerging Bipole

In a negative-polarity coronal hole, magnetic flux emergence, seen by the Solar Dynamics Observatory's (SDO) Helioseismic Magnetic Imager (HMI), begins at approximately 19:00 UT on March 3, 2016. The emerged magnetic field produced sunspots with penumbrae by 3:00 UT on March 4, which are a part of NOAA 12514. The emerging magnetic field is largely bipolar with the opposite-polarity fluxes spreading apart overall, but there is simultaneously some convergence and cancellation of opposite-polarity flux at the polarity inversion line (PIL) inside the emerging bipole. The emerging bipole shows obvious overall left-handed shear and/or twist in its magnetic field and corresponding clockwise rotation of the two poles of the bipole about each other as the bipole emerges. The eruption comes from inside the emerging bipole and blows it open to produce a CME observed by SOHO/LASCO. That eruption is preceded by flux cancellation at the emerging bipole's interior PIL, cancellation that plausibly builds a sheared and twisted flux rope above the interior PIL and fnally triggers the blow-out eruption of the flux rope via photospheric-convection-driven, slow tether-cutting reconnection of the legs of the sheared core field, low above the interior PIL, as proposed by van Ballegooijen and Martens (1989, ApJ, 343, 971) and Moore and Roumeliotis (1992, in Eruptive Solar Flares, ed. Z. Svestka, B.V. Jackson, and M.E. Machado [Berlin:Springer], 69). The production of this eruption is a (perhaps rare) counterexample to solar eruptions that result from external collisional shearing between opposite polarities from two distinct emerging and/or emerged bipoles (Chintzoglou et al., 2019, ApJ, 871:67).

Adams, Mitzi L.↗
NASA NTRS1996

Dynamical Evolution of a Coronal Streamer-Flux Rope System: 2. A Self-Consistent Non-Planar Magnetohydrodynamic Simulation

The dynamical response of a helmet streamer to a flux rope escape from the sub-photosphere is examined in a physically self-consistent manner within the approximation of axisymmetric three-dimensional magnetohydrodynamics (i.e., so-called '2 1/2 D'). In contrast to the previous planar analyses of Paper 1 (Wu, Guo, and Wang), the present study shows, with the inclusion of out-of-plane components of magnetic and velocity fields, that the magnetic configuration represents a helical flux rope instead of a planar bubble as shown in Paper 1. Because of this more physically-realistic configuration, we are able to examine the dynamical evolution of the helical flux rope's interaction with the helmet streamer. This process leads to the formation of two parts of the solar mass ejection: (i) the expulsion of the helmet dome due to eruption of this flux rope, and (ii) the flux rope's eruption itself. When this two-part feature propagates out to the interplanetary space, it exhibits all the physical characteristics of observed interplanetary magnetic clouds. These numerical simulations also show that the dynamical behavior of the streamer-flux rope system has three distinct states: (i) quasi-equilibrium, (ii) non-equilibrium, and (iii) eruptive state depending on the energy level of the flux rope.

Wu, S. T.↗