Magnetosphere–Ionosphere Coupling

2021 ◽  
Author(s):  
N. Achilleos ◽  
L. C. Ray ◽  
J. N. Yates
Keyword(s):  
Solar Wind ◽  
Electrical Current ◽  
Auroral Oval ◽  
Upper Atmosphere ◽  
Space Environment ◽  
Rotating Disc ◽  
Field Lines ◽  
Auroral Emissions ◽  
Rapid Rotator ◽  
Energy And Momentum

The process of magnetosphere-ionosphere coupling involves the transport of vast quantities of energy and momentum between a magnetized planet and its space environment, or magnetosphere. This transport involves extended, global sheets of electrical current, which flows along magnetic field lines. Some of the charged particles, which carry this current rain down onto the planet’s upper atmosphere and excite aurorae–beautiful displays of light close to the magnetic poles, which are an important signature of the physics of the coupling process. The Earth, Jupiter, and Saturn all have magnetospheres, but the detailed physical origin of their auroral emissions differs from planet to planet. The Earth’s aurora is principally driven by the interaction of its magnetosphere with the upstream solar wind—a flow of plasma continually emanating from the Sun. This interaction imposes a particular pattern of flow on the plasma within the magnetosphere, which in turn determines the morphology and intensity of the currents and aurorae. Jupiter, on the other hand, is a giant rapid rotator, whose main auroral oval is thought to arise from the transport of angular momentum between the upper atmosphere and the rotating, disc-like plasma in the magnetosphere. Saturn exhibits auroral behavior consistent with a solar wind–related mechanism, but there is also regular variability in Saturn’s auroral emissions, which is consistent with rotating current systems that transport energy between the magnetospheric plasma and localized vortices of flow in the upper atmosphere/ionosphere.

scholarly journals The dynamo-wind feedback loop : Assessing their non-linear interplay

2019 ◽  
Vol 15 (S354) ◽  
pp. 215-223
Author(s):  
Barbara Perri ◽  
Allan Sacha Brun ◽  
Antoine Strugarek ◽  
Victor Réville
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Coronal Holes ◽  
Coronal Magnetic Field ◽  
Space Environment ◽  
Cycle Phase ◽  
Activity Cycles ◽  
Spatio Temporal ◽  
Field Lines ◽  
The Impact

AbstractThough generated deep inside the convection zone, the solar magnetic field has a direct impact on the Earth space environment via the Parker spiral. It strongly modulates the solar wind in the whole heliosphere, especially its latitudinal and longitudinal speed distribution over the years. However the wind also influences the topology of the coronal magnetic field by opening the magnetic field lines in the coronal holes, which can affect the inner magnetic field of the star by altering the dynamo boundary conditions. This coupling is especially difficult to model because it covers a large variety of spatio-temporal scales. Quasi-static studies have begun to help us unveil how the dynamo-generated magnetic field shapes the wind, but the full interplay between the solar dynamo and the solar wind still eludes our understanding.We use the compressible magnetohydrodynamical (MHD) code PLUTO to compute simultaneously in 2.5D the generation and evolution of magnetic field inside the star via an α-Ω dynamo process and the corresponding evolution of a polytropic coronal wind over several activity cycles for a young Sun. A multi-layered boundary condition at the surface of the star connects the inner and outer stellar layers, allowing both to adapt dynamically. Our continuously coupled dynamo-wind model allows us to characterize how the solar wind conditions change as a function of the cycle phase, and also to quantify the evolution of integrated quantities such as the Alfvén radius. We further assess the impact of the solar wind on the dynamo itself by comparing our results with and without wind feedback.

scholarly journals A comparison between ion characteristics observed by the POLAR and DMSP spacecraft in the high-latitude magnetosphere

2004 ◽  
Vol 22 (3) ◽  
pp. 1033-1046 ◽  
Author(s):  
T. J. Stubbs ◽  
M. Lockwood ◽  
P. Cargill ◽  
M. Grande ◽  
B. Kellett ◽  
...  
Keyword(s):  
Solar Wind ◽  
Probability Distributions ◽  
Average Energy ◽  
Auroral Oval ◽  
Topside Ionosphere ◽  
Closed Field ◽  
Central Plasma ◽  
Ion Energies ◽  
Low Energies ◽  
Field Lines

Abstract. We study here the injection and transport of ions in the convection-dominated region of the Earth's magnetosphere. The total ion counts from the CAMMICE MICS instrument aboard the POLAR spacecraft are used to generate occurrence probability distributions of magnetospheric ion populations. MICS ion spectra are characterised by both the peak in the differential energy flux, and the average energy of ions striking the detector. The former permits a comparison with the Stubbs et al. (2001) survey of He2+ ions of solar wind origin within the magnetosphere. The latter can address the occurrences of various classifications of precipitating particle fluxes observed in the topside ionosphere by DMSP satellites (Newell and Meng, 1992). The peak energy occurrences are consistent with our earlier work, including the dawn-dusk asymmetry with enhanced occurrences on the dawn flank at low energies, switching to the dusk flank at higher energies. The differences in the ion energies observed in these two studies can be explained by drift orbit effects and acceleration processes at the magnetopause, and in the tail current sheet. Near noon at average ion energies of ≈1keV, the cusp and open LLBL occur further poleward here than in the Newell and Meng survey, probably due to convection- related time-of-flight effects. An important new result is that the pre-noon bias previously observed in the LLBL is most likely due to the component of this population on closed field lines, formed largely by low energy ions drifting earthward from the tail. There is no evidence here of mass and momentum transfer from the solar wind to the LLBL by non-reconnection coupling. At higher energies ≈2–20keV), we observe ions mapping to the auroral oval and can distinguish between the boundary and central plasma sheets. We show that ions at these energies relate to a transition from dawnward to duskward dominated flow, this is evidence of how ion drift orbits in the tail influence the location and behaviour of the plasma populations in the magnetosphere. Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetosphere-ionosphere interactions; magnetospheric configuration and dynamic)

scholarly journals Spiral structures and regularities in magnetic field variations and auroras

2012 ◽  
Vol 3 (1) ◽  
pp. 1-31 ◽  
Author(s):  
Y. I. Feldstein ◽  
L. I. Gromova ◽  
M. Förster ◽  
A. E. Levitin
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Current System ◽  
Temporal Distribution ◽  
Auroral Oval ◽  
Auroral Zone ◽  
Upper Atmosphere ◽  
Polar Coordinates ◽  
Magnetospheric Substorms ◽  
Field Lines

Abstract. The conception of spiral shaped precipitation regions, where solar corpuscles penetrate the upper atmosphere, was introduced into geophysics by C. Störmer and K. Birkeland at the beginning of the last century. Later, in the course of the XX-th century, spiral distributions were disclosed and studied in various geophysical phenomena. Most attention was devoted to spiral shapes in the analysis of regularities pertaining to the geomagnetic activity and auroras. We review the historical succession of perceptions about the number and positions of spiral shapes, that characterize the spatial-temporal distribution of magnetic disturbances. We describe the processes in the upper atmosphere, which are responsible for the appearance of spiral patterns. We considered the zones of maximal aurora frequency and of maximal particle precipitation intensity, as offered in the literature, in their connection with the spirals. We discuss the current system model, that is closely related to the spirals and that appears to be the source for geomagnetic field variations during magnetospheric substorms and storms. The currents in ionosphere and magnetosphere constitute together with field-aligned (along the geomagnetic field lines) currents (FACs) a common 3-D current system. At ionospheric heights, the westward and eastward electrojets represent characteristic elements of the current system. The westward electrojet covers the longitudinal range from the morning to the evening hours, while the eastward electrojet ranges from afternoon to near-midnight hours. The polar electrojet is positioned in the dayside sector at cusp latitudes. All these electrojets map along the magnetic field lines to certain plasma structures in the near-Earth space. The first spiral distribution of auroras was found based on observations in Antarctica for the nighttime-evening sector (N-spiral), and later in the nighttime-evening (N-spiral) and morning (M-spiral) sectors both in the Northern and Southern Hemispheres. The N- and M-spirals drawn in polar coordinates form an oval, along which one observes most often auroras in the zenith together with a westward electrojet. The nature of spiral distributions in geomagnetic field variations was unabmibuously interpreted after the discovery of the spiral's existence in the auroras had been established and this caused a change from the paradigm of the auroral zone to the paradigm of the auroral oval. Zenith forms of auroras are found within the boundaries of the auroral oval. The oval is therefore the region of most frequent precipitations of corpuscular fluxes with auroral energy, where anomalous geophysical phenomena occur most often and with maximum intensity. S. Chapman and L. Harang identified the existence of a discontinuity at auroral zone latitudes (Φ ∼ 67°) around midnight between the westward and eastward electrojets, that is now known as the Harang discontinuity. After the discovery of the auroral oval and the position of the westward electrojet along the oval, it turned out, that there is no discontinuity at a fixed latitude between the opposite electrojets, but rather a gap, the latitude of which varies smoothly between Φ ∼ 67° at midnight and Φ ∼ 73° at 20:00 MLT. In this respect the term ''Harang discontinuity'' represents no intrinsic phenomenon, because the westward electrojet does not experience any disruption in the midnight sector but continues without breaks from dawn to dusk hours.

scholarly journals A space hurricane over the Earth’s polar ionosphere

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qing-He Zhang ◽  
Yong-Liang Zhang ◽  
Chi Wang ◽  
Kjellmar Oksavik ◽  
Larry R. Lyons ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Upper Atmosphere ◽  
Electron Precipitation ◽  
Polar Ionosphere ◽  
Solar Wind Density ◽  
Strong Electron ◽  
Energy And Momentum ◽  
Zero Flow ◽  
Rain Precipitation

AbstractIn Earth’s low atmosphere, hurricanes are destructive due to their great size, strong spiral winds with shears, and intense rain/precipitation. However, disturbances resembling hurricanes have not been detected in Earth’s upper atmosphere. Here, we report a long-lasting space hurricane in the polar ionosphere and magnetosphere during low solar and otherwise low geomagnetic activity. This hurricane shows strong circular horizontal plasma flow with shears, a nearly zero-flow center, and a coincident cyclone-shaped aurora caused by strong electron precipitation associated with intense upward magnetic field-aligned currents. Near the center, precipitating electrons were substantially accelerated to ~10 keV. The hurricane imparted large energy and momentum deposition into the ionosphere despite otherwise extremely quiet conditions. The observations and simulations reveal that the space hurricane is generated by steady high-latitude lobe magnetic reconnection and current continuity during a several hour period of northward interplanetary magnetic field and very low solar wind density and speed.

scholarly journals Transpolar aurora: time evolution, associated convection patterns, and a possible cause

2005 ◽  
Vol 23 (5) ◽  
pp. 1917-1930 ◽  
Author(s):  
L. G. Blomberg ◽  
J. A. Cumnock ◽  
I. I. Alexeev ◽  
E. S. Belenkaya ◽  
S. Yu. Bobrovnikov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Auroral Oval ◽  
Plasma Convection ◽  
Ionosphere Plasma ◽  
Auroral Electrons ◽  
Field Lines ◽  
Convection Patterns ◽  
Auroral Emissions ◽  
Set Up

Abstract. We present two event studies illustrating the detailed relationships between plasma convection, field-aligned currents, and polar auroral emissions, as well as illustrating the influence of the Interplanetary Magnetic Field's y-component on theta aurora development. The transpolar arc of the theta aurorae moves across the entire polar region and becomes part of the opposite side of the auroral oval. Electric and magnetic field and precipitating particle data are provided by DMSP, while the POLAR UVI instrument provides measurements of auroral emissions. Ionospheric electrostatic potential patterns are calculated at different times during the evolution of the theta aurora using the KTH model. These model patterns are compared to the convection predicted by mapping the magnetopause electric field to the ionosphere using the Paraboloid Model of the magnetosphere. The model predicts that parallel electric fields are set up along the magnetic field lines projecting to the transpolar aurora. Their possible role in the acceleration of the auroral electrons is discussed. Keywords. Ionosphere (Plasma convection; Polar ionosphere) – Magnetospheric physics (Magnetosphereionosphere interactions)

scholarly journals Saturn's polar ionospheric flows and their relation to the main auroral oval

2004 ◽  
Vol 22 (4) ◽  
pp. 1379-1394 ◽  
Author(s):  
S. W. H. Cowley ◽  
E. J. Bunce ◽  
R. Prangé
Keyword(s):  
Solar Wind ◽  
Open Field ◽  
Auroral Oval ◽  
Closed Field ◽  
Polar Cap ◽  
Space Telescope ◽  
Planetary Rotation ◽  
Dayside Magnetopause ◽  
Field Lines ◽  
Upward Current

Abstract. We consider the flows and currents in Saturn's polar ionosphere which are implied by a three-component picture of large-scale magnetospheric flow driven both by planetary rotation and the solar wind interaction. With increasing radial distance in the equatorial plane, these components consist of a region dominated by planetary rotation where planetary plasma sub-corotates on closed field lines, a surrounding region where planetary plasma is lost down the dusk tail by the stretching out of closed field lines followed by plasmoid formation and pinch-off, as first described for Jupiter by Vasyliunas, and an outer region driven by the interaction with the solar wind, specifically by reconnection at the dayside magnetopause and in the dawn tail, first discussed for Earth by Dungey. The sub-corotating flow on closed field lines in the dayside magnetosphere is constrained by Voyager plasma observations, showing that the plasma angular velocity falls to around half of rigid corotation in the outer magnetosphere, possibly increasing somewhat near the dayside magnetopause, while here we provide theoretical arguments which indicate that the flow should drop to considerably smaller values on open field lines in the polar cap. The implied ionospheric current system requires a four-ring pattern of field-aligned currents, with distributed downward currents on open field lines in the polar cap, a narrow ring of upward current near the boundary of open and closed field lines, and regions of distributed downward and upward current on closed field lines at lower latitudes associated with the transfer of angular momentum from the planetary atmosphere to the sub-corotating planetary magnetospheric plasma. Recent work has shown that the upward current associated with sub-corotation is not sufficiently intense to produce significant auroral acceleration and emission. Here we suggest that the observed auroral oval at Saturn instead corresponds to the ring of upward current bounding the region of open and closed field lines. Estimates indicate that auroras of brightness from a few kR to a few tens of kR can be produced by precipitating accelerated magnetospheric electrons of a few keV to a few tens of keV energy, if the current flows in a region which is sufficiently narrow, of the order of or less than ~1000 km (~1° latitude) wide. Arguments are also given which indicate that the auroras should typically be significantly brighter on the dawn side of the oval than at dusk, by roughly an order of magnitude, and should be displaced somewhat towards dawn by the down-tail outflow at dusk associated with the Vasyliunas cycle. Model estimates are found to be in good agreement with data derived from high quality images newly obtained using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, both in regard to physical parameters, as well as local time effects. The implication of this picture is that the form, position, and brightness of Saturn's main auroral oval provide remote diagnostics of the magnetospheric interaction with the solar wind, including dynamics associated with magnetopause and tail plasma interaction processes. Key words. Magnetospheric physics (auroral phenomena, magnetosphere-ionosphere interactions, solar windmagnetosphere interactions)

scholarly journals Juno observations of spot structures and a split tail in Io-induced aurorae on Jupiter

Science ◽  
2018 ◽  
Vol 361 (6404) ◽  
pp. 774-777 ◽  
Author(s):  
A. Mura ◽  
A. Adriani ◽  
J. E. P. Connerney ◽  
S. Bolton ◽  
F. Altieri ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Energy ◽  
Auroral Oval ◽  
Upper Atmosphere ◽  
Vortex Street ◽  
Infrared Observations ◽  
High Energy Electrons ◽  
Galilean Moons ◽  
Field Lines ◽  
Magnetohydrodynamic Interaction

Jupiter’s aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet’s magnetic field lines. A northern and a southern main auroral oval are visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots, the extended tail is split in two. Both of Ganymede’s footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede’s magnetosphere. These features suggest that the magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated.

Quantitative surface damage studies by H.R.E.M.

1989 ◽  
Vol 47 ◽  
pp. 632-633
Author(s):  
S. R. Singh ◽  
H. J. Fan ◽  
L. D. Marks
Keyword(s):  
Solar Wind ◽  
Quantitative Analysis ◽  
Surface Science ◽  
Surface Damage ◽  
Space Environment ◽  
Oxygen Desorption ◽  
The Past ◽  
Diffusion Controlled ◽  
Original Observation ◽  
Substantial Interest

Since the original observation that the surfaces of materials undergo radiation damage in the electron microscope similar to that observed by more conventional surface science techniques there has been substantial interest in understanding these phenomena in more detail; for a review see. For instance, surface damage in a microscope mimics damage in the space environment due to the solar wind and electron beam lithographic operations.However, purely qualitative experiments that have been done in the past are inadequate. In addition, many experiments performed in conventional microscopes may be inaccurate. What is needed is careful quantitative analysis including comparisons of the behavior in UHV versus that in a conventional microscope. In this paper we will present results of quantitative analysis which clearly demonstrate that the phenomena of importance are diffusion controlled; more detailed presentations of the data have been published elsewhere.As an illustration of the results, Figure 1 shows a plot of the shrinkage of a single, roughly spherical particle of WO3 versus time (dose) driven by oxygen desorption from the surface.

Characteristics of the solar wind controlled auroral emissions

1998 ◽  
Vol 103 (A8) ◽  
pp. 17543-17557 ◽  
Author(s):  
K. Liou ◽  
P. T. Newell ◽  
C.-I. Meng ◽  
M. Brittnacher ◽  
G. Parks
Keyword(s):  
Solar Wind ◽  
Auroral Emissions
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