On Magnetic Helicity and Field-Aligned Currents in the Polar Ionosphere

Magnetic helicity, which is a measure of twist and linkage of magnetic field lines, is a useful quantity to investigate some processes occurring in space plasmas. In particular, there is a strong link between magnetic helicity, magnetic flux structures, turbulence and dissipation. We investigate the connection between the reduced magnetic helicity and the structure of field-aligned currents in the high-latitude ionosphere using high resolution (50 Hz) magnetic data collected on board the ESA Swarm constellation. We show the existence of a clear link between the multiscale coarse-grained structure of reduced magnetic helicity and the field-aligned currents. This finding strongly supports the idea that turbulence processes might be at the origin of the observed small-scale current structures. A discussion of the relevance of our results in the framework of the filamentary nature of the field-aligned current is also presented.This work is supported by Italian PNRA under contract PNRA18_00289-A &#8220;Space weather in Polar Ionosphere: the Role of Turbulence ".

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A New View of the Solar Interface Region from the Interface Region Imaging Spectrograph (IRIS)

Solar Physics ◽

10.1007/s11207-021-01826-0 ◽

2021 ◽

Vol 296 (5) ◽

Author(s):

Bart De Pontieu ◽

Vanessa Polito ◽

Viggo Hansteen ◽

Paola Testa ◽

Katharine K. Reeves ◽

...

Keyword(s):

Solar Atmosphere ◽

Resonant Absorption ◽

Interface Region ◽

Machine Learning Techniques ◽

Small Scale ◽

Wide Range ◽

Field Lines ◽

Far Ultraviolet ◽

Imaging Spectrograph

AbstractThe Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images and spectra of the solar atmosphere since July 2013. IRIS is the highest resolution observatory to provide seamless coverage of spectra and images from the photosphere into the low corona. The unique combination of near- and far-ultraviolet spectra and images at sub-arcsecond resolution and high cadence allows the tracing of mass and energy through the critical interface between the surface and the corona or solar wind. IRIS has enabled research into the fundamental physical processes thought to play a role in the low solar atmosphere such as ion–neutral interactions, magnetic reconnection, the generation, propagation, and dissipation of waves, the acceleration of non-thermal particles, and various small-scale instabilities. IRIS has provided insights into a wide range of phenomena including the discovery of non-thermal particles in coronal nano-flares, the formation and impact of spicules and other jets, resonant absorption and dissipation of Alfvénic waves, energy release and jet-like dynamics associated with braiding of magnetic-field lines, the role of turbulence and the tearing-mode instability in reconnection, the contribution of waves, turbulence, and non-thermal particles in the energy deposition during flares and smaller-scale events such as UV bursts, and the role of flux ropes and various other mechanisms in triggering and driving CMEs. IRIS observations have also been used to elucidate the physical mechanisms driving the solar irradiance that impacts Earth’s upper atmosphere, and the connections between solar and stellar physics. Advances in numerical modeling, inversion codes, and machine-learning techniques have played a key role. With the advent of exciting new instrumentation both on the ground, e.g. the Daniel K. Inouye Solar Telescope (DKIST) and the Atacama Large Millimeter/submillimeter Array (ALMA), and space-based, e.g. the Parker Solar Probe and the Solar Orbiter, we aim to review new insights based on IRIS observations or related modeling, and highlight some of the outstanding challenges.

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Inverse cascade in the structure of substorm aurora and non-linear dynamics of field-aligned current filaments

Annales Geophysicae ◽

10.5194/angeo-29-1349-2011 ◽

2011 ◽

Vol 29 (8) ◽

pp. 1349-1354 ◽

Cited By ~ 3

Author(s):

B. V. Kozelov ◽

I. V. Golovchanskaya ◽

O. V. Mingalev

Keyword(s):

Coarse Grained ◽

Small Scale ◽

Inverse Cascade ◽

Non Linear ◽

Substorm Activity ◽

Field Aligned Current ◽

Current Filaments ◽

Scaling Features ◽

Linear Interactions ◽

Auroral Luminosity

Abstract. We investigate time evolution of scaling index αA that characterizes auroral luminosity fluctuations at the beginning of substorm expansion. With the use of UVI images from the Polar satellite, it is shown that αA typically varies from values less than unity to ~1.5, increasing with breakup progress. Similar scaling features were previously reported for fluctuations at smaller scales from all-sky TV observations. If this signature is interpreted in terms of non-linear interactions between scales, it means that the power of small-scale fluctuations is transferred with time to larger scales, a kind of the inverse cascade. Scaling behavior in the aurora during substorm activity is compared with that in the field-aligned currents simulated numerically in the model of non-linear interactions of Alfvénic coherent structures, according to the Chang et al. (2004) scenario. This scenario also suggests an inverse cascade, manifesting in clustering of small-scale field-aligned current filaments of the same polarity and formation of "coarse-grained" structures of field-aligned currents.

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A model of the plasma flow and current in Saturn's polar ionosphere under conditions of strong Dungey cycle driving

Annales Geophysicae ◽

10.5194/angeo-24-1029-2006 ◽

2006 ◽

Vol 24 (3) ◽

pp. 1029-1055 ◽

Cited By ~ 16

Author(s):

C. M. Jackman ◽

S. W. H. Cowley

Keyword(s):

Flow Pattern ◽

Hubble Space Telescope ◽

Plasma Source ◽

Closed Field ◽

Current Layer ◽

Polar Ionosphere ◽

Solar Wind Interaction ◽

Outer Magnetosphere ◽

Field Aligned Current ◽

Field Lines

Abstract. We propose a simple model of the flow and currents in Saturn's polar ionosphere. This model is motivated by theoretical reasoning, and guided quantitatively by in situ field and flow data from space missions, ground-based IR Doppler measurements, and Hubble Space Telescope images. The flow pattern consists of components which represent (1) plasma sub-corotation in the middle magnetosphere region resulting from plasma pick-up and radial transport from internal sources; (2) the Vasyliunas-cycle of internal plasma mass-loss down the magnetospheric tail at higher latitudes; and (3) the polar Dungey-cycle flow driven by the solar wind interaction. Upstream measurements of the interplanetary magnetic field (IMF) indicate the occurrence of both extended low-field rarefaction intervals with essentially negligible Dungey-cycle flow, and few-day high-field compression regions in which the Dungey-cycle voltage peaks at a few hundred kV. Here we model the latter conditions when the Dungey-cycle is active, advancing on previous axi-symmetric models which may be more directly applicable to quiet conditions. For theoretical convenience the overall flow pattern is constructed by adding together two components - a purely rotational flow similar to previous axi-symmetric models, and a sun-aligned twin vortex representing the dawn-dusk asymmetry effects associated with the Vasyliunas-and Dungey-cycle flows. We calculate the horizontal ionospheric current associated with the flow and the field-aligned current from its divergence. These calculations show that a sheet of upward-directed field-aligned current flows at the boundary of open field lines which is strongly modulated in local-time by the Dungey-cycle flows. We then consider implications of the field-aligned current for magnetospheric electron acceleration and aurorae using two plasma source populations (hot outer magnetospheric electrons and cool dense magnetosheath electrons). Both sources display a strong dawn-dusk asymmetry in the accelerating voltages required and the energy fluxes produced, resulting from the corresponding asymmetry in the current. The auroral intensities for the outer magnetosphere source are typically ~50 kR at dawn and ~5 kR at dusk, in conformity with recent auroral observations under appropriate conditions. However, those for the magnetosheath source are much smaller. When the calculated precipitating electron energy flux values are integrated across the current layer and around the open closed field line boundary, this yields total UV output powers of ~10 GW for the hot outer magnetosphere source, which also agrees with observations.

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An extended TRANSCAR model including ionospheric convection: simulation of EISCAT observations using inputs from AMIE

Annales Geophysicae ◽

10.5194/angeo-23-419-2005 ◽

2005 ◽

Vol 23 (2) ◽

pp. 419-431 ◽

Cited By ~ 27

Author(s):

P.-L. Blelly ◽

C. Lathuillère ◽

B. Emery ◽

J. Lilensten ◽

J. Fontanari ◽

...

Keyword(s):

Large Scale ◽

Frictional Heating ◽

Polar Ionosphere ◽

Energy Inputs ◽

Early Afternoon ◽

High Latitude Ionosphere ◽

Field Lines ◽

Moment Approach ◽

The Magnetic Field ◽

Good Agreement

Abstract. The TRANSCAR ionospheric model was extended to account for the convection of the magnetic field lines in the auroral and polar ionosphere. A mixed Eulerian-Lagrangian 13-moment approach was used to describe the dynamics of an ionospheric plasma tube. In the present study, one focuses on large scale transports in the polar ionosphere. The model was used to simulate a 35-h period of EISCAT-UHF observations on 16-17 February 1993. The first day was magnetically quiet, and characterized by elevated electron concentrations: the diurnal F2 layer reached as much as 1012m-3, which is unusual for a winter and moderate solar activity (F10.7=130) period. An intense geomagnetic event occurred on the second day, seen in the data as a strong intensification of the ionosphere convection velocities in the early afternoon (with the northward electric field reaching 150mVm-1) and corresponding frictional heating of the ions up to 2500K. The simulation used time-dependent AMIE outputs to infer flux-tube transports in the polar region, and to provide magnetospheric particle and energy inputs to the ionosphere. The overall very good agreement, obtained between the model and the observations, demonstrates the high ability of the extended TRANSCAR model for quantitative modelling of the high-latitude ionosphere; however, some differences are found which are attributed to the precipitation of electrons with very low energy. All these results are finally discussed in the frame of modelling the auroral ionosphere with space weather applications in mind.

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The role of collective identifications in family processes of post-trauma reconstruction: An exploratory study with Kurdish refugee families and their diasporic community

Kurdish Studies ◽

10.33182/ks.v5i2.440 ◽

2017 ◽

Vol 5 (2) ◽

pp. 107-133 ◽

Cited By ~ 7

Author(s):

Ruth Kevers ◽

Peter Rober ◽

Lucia De Haene

Keyword(s):

Thematic Analysis ◽

Exploratory Study ◽

Meaning Making ◽

Family Processes ◽

Small Scale ◽

Refugee Families ◽

Family Contexts ◽

Diasporic Community ◽

And Coping

While collective identifications of diasporic Kurds have attracted considerable scholarly interest, their possible role in familial processes of post-trauma reconstruction has hardly been studied. The aim of this article is therefore to develop an explorative understanding of the deployment and meaning of collective identifications in intimate family contexts by examining the interconnectedness between the transmission of cultural and political belonging and post-trauma meaning-making and coping in Kurdish refugee families. After contextualising diasporic Kurds’ collective identifications through an ethnographic depiction of the Kurdish diasporic community in Belgium, this article reports on findings from a small-scale, exploratory study with five Kurdish refugee families in Belgium. Thematic analysis of family and parent interviews indicates how cultural and political identifications may operate as sources of (1) dealing with cultural bereavement and loss; (2) commemorating trauma; and (3) reversing versus reiterating trauma. Overall, this study’s findings support an explorative understanding of collective identifications as meaningful resources in families’ post-trauma reconstruction.ABSTRACT IN KURMANJIRola nasnameyên komelî di pêvajoyên malbatî yên vesazkirina paş-trawmayê de: Xebateke raveker li ser malbatên kurd ên penaber û civakên wan ên dîasporayêTevî ku nasnameyên komelî yên kurdên dîasporayê ta radeyeke baș bûye mijara lêkolînan, rola wan a muhtemel di pêvajoyên malbatî yên vesazkirina (selihandin) paş-trawmayê qet nehatine vekolîn. Lewma armanca vê gotarê ew e têgihiştineke raveker pêş bixe li ser rol û wateya nasnameyên komelî yên di çarçoveya mehremiya malbatê de, ku vê yekê jî dê bi rêya vekolîna wê têkiliya rijd bike ya di navbera neqlkirina aidiyetên çandî-siyasî û rêyên sazkirina wateyê û serederîkirina li dû trawmayê di nav malbatên kurd ên penaber de. Piştî diyarkirina çarçoveya nasnameya komelî ya Kurdên diasporayê bi rêya teswîreke etnografîk a cemaeta diasporaya Kurd li Belçîkayê, ev gotar encamên ji xebateke biçûk a bi pênc malbatên kurd ên penaber ên li Belçîkayê pêşkêş dike. Tehlîla babetî ya hevpeyvînên ligel malbatan û dayik û bavan nîşan dide ka çawa nasnameyên çandî û siyasî dikarin bibin çavkanî ji bo (1) serederîkirina bi mehrûmiyeta çandî û windahiyên xwe; (2) bibîranîna trawmayê; û (3) kêmrengkirin an, beramber vê yekê, dubarekirina trawmayê. Bi giştî, encamên vê xebatê wê têgihiştineke raveker tesdîq dikin ku nasnameyên kolektîf çavkaniyên kêrhatî ne di vesazkirina paş-trawmayê ya malbatan de. ABSTRACT IN SORANIDewrî nasname bekomellekan le prose binemalleyîyekanî sazkirdinewey paş-trawmayîda: lêkollîneweyekî şirovekarî binemalle penabere kurdekan û civatî ewan le diyasporaLe katêkda nasname bekomellekanî kurdekanî diyaspora le layen şarezakanewe giringîyekî berçawî pê drawe û serincî ewanî bo lay xoyî rakêşawe, bellam sebaret be egerî dewrî prose binemalleyîyekanî sazkirdinewey paş-tirawma be degmen lêkollîneweyek encam drawe. Ke wate, amancî em wutare perepêdan be têgeyîştinêkî şirovekarane lemerr bekarhênan û manay nasname bekomellekan le bestênekanî têkellawîy binemalleyîdaye, ke le rêgey peywendîy nêwan rewtî gwastineweyî grêdraweyî kultûrî û siyasî, sazbûnî mana û herweha rahatin legell kêşekanî qonaẍî paş tirawma le binemalle kurde penaberekanda taqî krawetewe. Dway awirrdanewe le civakî diyasporay kurd le Belcîka, nasname bekomellekanî kurdekanî diyaspora le bestênî xoyda xwêndinewey bo krawe û bem gêreye lem wutareda lêkollîneweyekî şirovekarane bo qebareyekî biçûk le pênc binemalley kurdî penaber le Belcîka dekrê û encamekanî billaw dekrêtewe. Şîkarîyekî babetiyaney wutuwêj legell binemalle û dayk û bawkekan nîşanî dedat ke çon dekrê nasname kultûrî û siyasîyekan wek serçaweyek bo em sê mijare derbikewn: (1) gîrodebûn be ledestçûn û bizirbûnî kultûr; (2) webîrhênanewey tirawma; û (3) pêçewanebûnî tirawma leberamber dûbarebûneweyda. Beşêweyekî giştî, encamekanî em lêkollîneweye piştgîrî le têgeyîştinêkî şirovekarane le nasname bekomellekan dekat ke wekû serçaweyekî giring bo sazkirdinewey binemallekan le dway qonaẍî paş-tirawma seyr dekrêt.

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GOELRO plan is 100 years old

Elektrichestvo ◽

10.24160/0013-5380-2020-12-4-9 ◽

2020 ◽

Vol 12 (12) ◽

pp. 4-9

Author(s):

Pavel A. BUTYRIN ◽

Keyword(s):

Agricultural Production ◽

Historical Context ◽

Soviet Period ◽

Small Scale ◽

Efficient Production ◽

Soviet Republic ◽

Starting Conditions ◽

Per Capita ◽

State Plan

The historical context in which the State Plan for Electrification of Russia (GOELRO) was developed, establishment of the GOELRO Commission, the GOELRO Plan content, the specific features of its implementation, and the role of the plan in the soviet period of Russia’s history are considered. Attention is paid to the electrification plants of other countries and territories of all inhabited continents, and to the participation of states in the electrification of countries and regions with small-scale and agricultural production in the 1920 s. The specific features pertinent to the electrification of the Russian Socialist Federative Soviet Republic are pointed out, namely, low starting conditions (in 1923, the energy consumption per capita in Russia was 100 times lower than that in Norway), its being state-owned in nature and revolutionary in its purpose: to get done with the main upheavals in the country and to shift the national economy for fore efficient production. The role of V.I. Lenin and G.M. Krzhizhanovsky, who were the initiators of the electrification of Russia, is analyzed in detail. A conclusion is drawn about the need to study both the GOELRO Plan itself and the specific features and circumstances of its implementation within the framework of training modern specialists in electrical engineering.

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