ICE observations of Comet Giacobini-Zinner

The first spacecraft encounter with a comet took place on 11 September 1985 when the International Cometary Explorer spacecraft passed through the tail of Comet Giacobini-Zinner at a distance of 7800 km from the nucleus. It provided the first definitive in-situ information concerning the interaction of a cometary atmosphere with the flowing solar-wind plasma, and the results of initial analyses are reviewed in this paper. Large-scale mhd aspects of the interaction largely conform to prior expectation. The flow surrounding the comet is mass-loaded and slowed by situ ionization and pick-up of heavy cometary neutrals, and the solar-wind magnetic field consequently becomes draped around the obstacle, and forms an induced magnetotail. Substantial evidence exists for the permanent presence of a weak shock lying in the subsolar mass-loaded region upstream from the comet, through whether the spacecraft itself passed through shocks on the cometary flanks remains controversial. There is no doubt, however, that a sharp boundary was observed both inbound and outbound (centred on ca. 09h29 and 12h20 U.T.) whose width is an energetic heavyion Larmor radius ( ca. 10 4 km), where the flow is deflected away from the comet and slowed, and where the magnetic field and plasma become compressed and very turbulent. The location of this boundary is also consistent with that expected for a weak shock based upon the known Giacobini-Zinner water-molecule production rate. An unexpected feature of the interaction was the extreme levels of field and plasma turbulence, and broadband wave activity observed in the region of massloaded flow.

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HelioSwarm: The Nature of Turbulence in Space Plasmas

10.5194/egusphere-egu21-12092 ◽

2021 ◽

Author(s):

Harlan Spence ◽

Kristopher Klein ◽

HelioSwarm Science Team

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Large Scale ◽

Solar Wind Plasma ◽

Turbulent Energy ◽

Space Plasmas ◽

Plasma Parameters ◽

Astrophysical Plasmas ◽

Ion Distributions ◽

Background Magnetic Field

Recently selected for phase A study for NASA&#8217;s Heliophysics MidEx Announcement of Opportunity, the HelioSwarm Observatory proposes to transform our understanding of the physics of turbulence in space and astrophysical plasmas by deploying nine spacecraft to measure the local plasma and magnetic field conditions at many points, with separations between the spacecraft spanning MHD and ion scales.&#160;&#160;HelioSwarm resolves the transfer and dissipation of turbulent energy in weakly-collisional magnetized plasmas with a novel configuration of spacecraft in the solar wind. These simultaneous multi-point, multi-scale measurements of space plasmas allow us to reach closure on two science goals comprised of six science objectives: (1) reveal how turbulent energy is transferred in the most probable, undisturbed solar wind plasma and distributed as a function of scale and time; (2) reveal how this turbulent cascade of energy varies with the background magnetic field and plasma parameters in more extreme solar wind environments; (3) quantify the transfer of turbulent energy between fields, flows, and ion heat; (4) identify thermodynamic impacts of intermittent structures on ion distributions; (5) determine how solar wind turbulence affects and is affected by large-scale solar wind structures; and (6) determine how strongly driven turbulence differs from that in the undisturbed solar wind.&#160;

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Statistical relations between in-situ measured Bz component and thermospheric density variations

10.5194/egusphere-egu21-4773 ◽

2021 ◽

Author(s):

Sofia Kroisz ◽

Lukas Drescher ◽

Manuela Temmer ◽

Sandro Krauss ◽

Barbara Süsser-Rechberger ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Satellite Orbit ◽

Solar Wind Plasma ◽

Statistical Investigation ◽

Neutral Density ◽

Special Focus ◽

Short Term

Through advanced statistical investigation and evaluation of solar wind plasma and magnetic field data, we investigate the statistical relation between the magnetic field Bz component, measured at L1, and Earth&#8217;s thermospheric neutral density. We will present preliminary results of the time series analyzes using in-situ plasma and magnetic field measurements from different spacecraft in near Earth space (e.g., ACE, Wind, DSCOVR) and relate those to derived thermospheric densities from various satellites (e.g., GRACE, CHAMP). The long and short term variations and dependencies in the solar wind data are related to variations in the neutral density of the thermosphere and geomagnetic indices. Special focus is put on the specific signatures that stem from coronal mass ejections and stream or corotating interaction regions.&#160; The results are used to develop a novel short-term forecasting model called SODA (Satellite Orbit DecAy). This is a joint study between TU Graz and University of Graz funded by the FFG Austria (project &#8220;SWEETS&#8221;).

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Predictions of local ground geomagnetic field fluctuations during the 7-10 November 2004 events studied with solar wind driven models

Annales Geophysicae ◽

10.5194/angeo-23-3095-2005 ◽

2005 ◽

Vol 23 (9) ◽

pp. 3095-3101 ◽

Cited By ~ 12

Author(s):

P. Wintoft ◽

M. Wik ◽

H. Lundstedt ◽

L. Eliasson

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Flow Direction ◽

Strong Dependence ◽

Solar Wind Plasma ◽

Magnetic Field Data ◽

Solar Wind Magnetic Field ◽

Solar Wind Flow ◽

Field Fluctuations ◽

Ground Magnetic

Abstract. The 7-10 November 2004 period contains two events for which the local ground magnetic field was severely disturbed and simultaneously, the solar wind displayed several shocks and negative Bz periods. Using empirical models the 10-min RMS and at Brorfelde (BFE, 11.67° E, 55.63° N), Denmark, are predicted. The models are recurrent neural networks with 10-min solar wind plasma and magnetic field data as inputs. The predictions show a good agreement during 7 November, up until around noon on 8 November, after which the predictions become significantly poorer. The correlations between observed and predicted log RMS is 0.77 during 7-8 November but drops to 0.38 during 9-10 November. For RMS the correlations for the two periods are 0.71 and 0.41, respectively. Studying the solar wind data for other L1-spacecraft (WIND and SOHO) it seems that the ACE data have a better agreement to the near-Earth solar wind during the first two days as compared to the last two days. Thus, the accuracy of the predictions depends on the location of the spacecraft and the solar wind flow direction. Another finding, for the events studied here, is that the and models showed a very different dependence on Bz. The model is almost independent of the solar wind magnetic field Bz, except at times when Bz is exceptionally large or when the overall activity is low. On the contrary, the model shows a strong dependence on Bz at all times.

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Magnetospheric Processes Possibly Related to the Origin of Cosmic Rays

Symposium - International Astronomical Union ◽

10.1017/s0074180900074921 ◽

1981 ◽

Vol 94 ◽

pp. 373-391

Author(s):

Gerhard Haerendel

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Small Scale ◽

Shear Stresses ◽

Acceleration Process ◽

Dayside Magnetopause ◽

Field Lines ◽

The Magnetic Field ◽

Auroral Particles

Two processes are discussed which violate the frozen-in condition in a highly conducting plasma, reconnection and the auroral acceleration process. The first applies to situations in which . It plays an important role in the interaction of the solar wind with the Earth's magnetic field and controls energy input into as well as energetic particle release from the magnetosphere. Detailed in situ studies of the process on the dayside magnetopause reveal its transient and small-scale nature. The auroral acceleration process occurs in the low magnetosphere (β « 1) and accompanies sudden releases of magnetic shear stresses which exist in large-scale magnetospheric-ionospheric current circuits. The process is interpreted as a kind of breaking. The movements of the magnetospheric plasma which lead to a relief of the magnetic tensions occur in thin sheets and are decoupled along the magnetic field lines by parallel electric potential drops. It is this voltage that accelerates the primary auroral particles. The visible arcs are then traces of the magnetic breaking process at several 1000 km altitude.

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Interplanetary magnetic field rotations followed from L1 to the ground: the response of the Earth's magnetosphere as seen by multi-spacecraft and ground-based observations

Annales Geophysicae ◽

10.5194/angeo-29-1549-2011 ◽

2011 ◽

Vol 29 (9) ◽

pp. 1549-1569 ◽

Cited By ~ 6

Author(s):

M. Volwerk ◽

J. Berchem ◽

Y. V. Bogdanova ◽

O. D. Constantinescu ◽

M. W. Dunlop ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Dynamic Pressure ◽

Earth’S Magnetosphere ◽

Solar Wind Magnetic Field ◽

Earth's Magnetosphere ◽

High Dynamic ◽

First Time ◽

Current Systems ◽

The Magnetic Field

Abstract. A study of the interaction of solar wind magnetic field rotations with the Earth's magnetosphere is performed. For this event there is, for the first time, a full coverage over the dayside magnetosphere with multiple (multi)spacecraft missions from dawn to dusk, combined with ground magnetometers, radar and an auroral camera, this gives a unique coverage of the response of the Earth's magnetosphere. After a long period of southward IMF Bz and high dynamic pressure of the solar wind, the Earth's magnetosphere is eroded and compressed and reacts quickly to the turning of the magnetic field. We use data from the solar wind monitors ACE and Wind and from magnetospheric missions Cluster, THEMIS, DoubleStar and Geotail to investigate the behaviour of the magnetic rotations as they move through the bow shock and magnetosheath. The response of the magnetosphere is investigated through ground magnetometers and auroral keograms. It is found that the solar wind magnetic field drapes over the magnetopause, while still co-moving with the plasma flow at the flanks. The magnetopause reacts quickly to IMF Bz changes, setting up field aligned currents, poleward moving aurorae and strong ionospheric convection. Timing of the structures between the solar wind, magnetosheath and the ground shows that the advection time of the structures, using the solar wind velocity, correlates well with the timing differences between the spacecraft. The reaction time of the magnetopause and the ionospheric current systems to changes in the magnetosheath Bz seem to be almost immediate, allowing for the advection of the structure measured by the spacecraft closest to the magnetopause.

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The solar wind angular-momentum flux observed during Solar Orbiter's first orbit

10.5194/egusphere-egu21-6306 ◽

2021 ◽

Author(s):

Daniel Verscharen ◽

David Stansby ◽

Adam Finley ◽

Christopher Owen ◽

Timothy Horbury ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Angular Momentum ◽

Momentum Flux ◽

Large Scale ◽

Magnetic Field Data ◽

Proton Data ◽

Scale Properties ◽

Orbiter Mission

The Solar Orbiter mission is currently in its cruise phase, during which the spacecraft's in-situ instrumentation measures the solar wind and the electromagnetic fields at different heliocentric distances.&#160;We evaluate the solar wind angular-momentum flux by combining proton data from the Solar Wind Analyser (SWA) Proton-Alpha Sensor (PAS) and magnetic-field data from the Magnetometer (MAG) instruments on board Solar Orbiter during its first orbit. This allows us to evaluate the angular momentum in the protons in addition to that stored in magnetic-field stresses, and compare these to previous observations from other spacecraft. We discuss the statistical properties of the angular-momentum flux and its dependence on solar-wind properties.&#160;Our results largely agree with previous measurements of the solar wind&#8217;s angular-momentum flux in the inner heliosphere and demonstrate the potential for future detailed studies of large-scale properties of the solar wind with the data from Solar Orbiter.

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Satellite observations of currents and waves in space plasmas

Laser and Particle Beams ◽

10.1017/s0263034600005425 ◽

1988 ◽

Vol 6 (3) ◽

pp. 503-511 ◽

Cited By ~ 2

Author(s):

T. A. Potemra ◽

M. J. Engebretson ◽

L. J. Zanetti ◽

R. E. Erlandson ◽

P. F. Bythrow

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Geomagnetic Field ◽

Large Scale ◽

Field Experiments ◽

Outer Space ◽

Solar Wind Plasma ◽

Field Configuration ◽

The Earth ◽

Field Lines

When viewed from outer space, the earth's magnetic field does not resemble a simple dipole, but is severely distorted into a comet-shaped configuration by the continuous flow of solar wind plasma. A complicated system of currents flows within this distorted magnetic field configuration called the ‘magnetosphere’ (See figure 1). For example, the compression of the geomagnetic field by the solar wind on the dayside of the earth is associated with a large-scale current flowing across the geomagnetic field lines, called the ‘Chapman-Ferraro’ or magnetopause current. The magnetospheric system includes large-scale currents that flow in the ‘tail’, the ring current that flows at high altitudes around the equator of the earth, field-aligned ‘Birkeland’ currents that flow along geomagnetic field lines into and away from the two auroral regions, and a complex system of currents that flows completely within the layers of the ionosphere, the earth's ionized atmosphere. The intensities of these various currents reach millions of amperes and are closely related to solar activity. The geomagnetic field lines can also oscillate, like giant vibrating strings, at specified resonant frequencies. The effects of these vibrations, sometimes described as ‘standing Alfvén waves’, have been observed on the ground in magnetic field recordings dating back to the beginning of the century. Observations of currents and waves with satellite-borne magnetic field experiments have provided a new perspective on the complicated plasma processes that occur in the magnetosphere. Some of the new observations are described here.

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Solar Wind Disconnects Venus's Magnetotail

Eos ◽

10.1029/2016eo054773 ◽

2016 ◽

Vol 97 ◽

Author(s):

Aleida Higginson

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Wind Magnetic Field ◽

Polarity Reversals ◽

The Magnetic Field

Polarity reversals in the solar wind magnetic field disconnect the magnetic field trailing behind Venus, allowing ions from the atmosphere to escape.

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The solar wind between 0.1 and 1 AU: Parker Solar Probe - BepiColombo radial alignment and BepiColombo - ACE magnetic alignment

10.5194/epsc2021-66 ◽

2021 ◽

Author(s):

Tommaso Alberti ◽

Anna Milillo ◽

Daniel Heyner ◽

Lina Z. Hadid

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Wind Plasma ◽

Radial Dependence ◽

Magnetic Alignment ◽

Field Observations ◽

Similar Nature ◽

Self Similar ◽

High Order Statistics ◽

The Magnetic Field

At the beginning of September 2020 ACE and BepiColombo spent several hours in an interesting magnetically connected configuration, while at the end of the same month Parker Solar Probe (PSP) and BepiColombo were radially aligned. Being PSP orbiting near 0.1 AU, BepiColombo near 0.6 AU, and ACE at 1 AU, these geometries are of particular interest for investigating the evolution of solar wind properties at different heliocentric distances by observing the same solar wind plasma parcels.&#160; In this contribution we use magnetic field observations from pairs of spacecraft to characterize both the topology of the magnetic field at different heliocentric distances (scalings and high-order statistics) and how it evolves when moving from near-Sun to far-Sun locations. We observe a breakdown of the statistical self-similar nature of the solar wind plasma due to an increase of the intermittency level when moving away from the Sun. These results support previous evidences on the radial dependence of solar wind scaling behavior and can open a novel framework for modeling magnetic field topological changes across the Heliosphere.

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Analysis of the Internal structure of the Streamer Blow Out Observed by the Parker Solar Probe during the First Solar Encounter

10.5194/egusphere-egu2020-22182 ◽

2020 ◽

Author(s):

Teresa Nieves-Chinchilla ◽

Adam Szabo ◽

Kelly E. Korreck ◽

Nathalia Alzate ◽

Laura A. Balmaceda ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Internal Structure ◽

Flux Rope ◽

Internal Force ◽

Slow Solar Wind ◽

Angle Distribution ◽

The Hours ◽

The Magnetic Field

We present an analysis of the internal structure of a coronal mass ejection (CME)&#160;detected by in situ&#160;instruments onboard the Parker Solar Probe (PSP) spacecraft during its first solar&#160;encounter. On 2018 November 11 at 23:53 UT, the FIELDS magnetometer measured an increase&#160;in strength of the magnetic field as well as a coherent change in the field direction. The SWEAP&#160;instrument simultaneously detected the low proton temperature and signatures of bi-directionality in&#160;the electron pitch angle distribution (PAD). These signatures are indicative of a CME embedded in the&#160;slow solar wind. In conjunction with PSP was the STEREO A spacecraft, which enabled the remote&#160;observation of a streamer blow-out by the SECCHI suite of instruments. The source at the Sun of&#160;the slow and well-structured&#160;flux-rope was identified in an overlying streamer.Our detailed inspection of the internal transient structure magnetic properties suggests high complexity&#160;in deviations from an ideal&#160;flux rope 3D topology. Reconstructions of the magnetic field&#160;conguration reveal a highly distorted structure consistent with the highly elongated `bubble' observed&#160;remotely. A double-ring substructure observed in the SECCHI-COR2 eld of view (FOV) is&#160;suggestive of a double internal&#160;flux rope. Furthermore, we describe a scenario in which mixed topology&#160;of a closed&#160;flux rope is combined with the magnetically open structure, which helps explain the&#160;flux&#160;dropout observed in the measurements of the electron PAD. Our justication for this is the plethora&#160;of structures observed by the EUV imager (SECCHI-EUVI) in the hours preceding the streamer blowout&#160;evacuation. Finally, taking advantage of the unique observations from PSP, we explore the first&#160;stages of the effects of coupling with the solar wind and the evolutionary processes in the magnetic&#160;structure. We found evidence of bifurcated current sheets in the structure boundaries suggestive of&#160;magnetic reconnection. Our analysis of the internal force imbalance indicates that internal Lorentz&#160;forces continue to dominate the evolution of the structure in the COR2 FOV and serves as the main&#160;driver of the internal&#160;flux rope distortion as detected in situ at PSP solar distance.

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