Mesoscale Features in the Global Geospace Response to the March 12, 2012 Storm

The geospace response to coronal mass ejections includes phenomena across many regions, from reconnection at the dayside and magnetotail, through the inner magnetosphere, to the ionosphere, and even to the ground. Phenomena occurring in each region are often connected to each other through the magnetic field, but that field undergoes dynamic changes during storms and substorms. Improving our understanding of the geospace response to storms requires a global picture that enables us to observe all the regions simultaneously with both spatial and temporal resolution. Using the Energetic Neutral Atom (ENA) imager on the Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) mission, a temperature map can be calculated to provide a global view of the magnetotail. These maps are combined with in situ measurements at geosynchronous orbit from GOES 13 and 15, auroral images from all sky imagers (ASIs), and ground magnetometer measurements to examine the global geospace response of a coronal mass ejection (CME) driven event on March 12th, 2012. Mesoscale features in the magnetotail are observed throughout the interval, including prior to the storm commencement and during the main phase, which has implications for the dominant processes that lead to pressure buildup in the inner magnetosphere. Auroral enhancements that can be associated with these magnetotail features through magnetosphere-ionosphere coupling are observed to appear only after global reconfigurations of the magnetic field.

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A study of the electrode/solution interface during electrochemical reactions by digital holography

Journal of the Serbian Chemical Society ◽

10.2298/jsc0610091c ◽

2006 ◽

Vol 71 (10) ◽

pp. 1091-1093 ◽

Cited By ~ 1

Author(s):

Shenhao Chen

Keyword(s):

Magnetic Field ◽

Sulfuric Acid ◽

Acid Solution ◽

Digital Holography ◽

Anodic Process ◽

Electrochemical Reactions ◽

Dynamic Changes ◽

Solution Interface ◽

The Magnetic Field

Digital holography was used to study in situ the dynamic changes of the electrode/solution interface and the solution near the electrode during the anodic process of iron in a sulfuric acid solution. The effects of chloride, bromide and iodine ions on this process were also investigated. The magnetic field also has effects on the process. The effects are discussed in combination with SEM results. .

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Observation of an inner magnetosphere electric field associated with a BBF-like flow and PBIs

Annales Geophysicae ◽

10.5194/angeo-27-1489-2009 ◽

2009 ◽

Vol 27 (4) ◽

pp. 1489-1500

Author(s):

T. Johansson ◽

J. W. Bonnell ◽

C. Cully ◽

E. Donovan ◽

J. Raeder ◽

...

Keyword(s):

Magnetic Field ◽

Electric Field ◽

Electric Fields ◽

Plasma Flow ◽

Maximum Velocity ◽

Inner Magnetosphere ◽

Ion Flow ◽

Field Activity ◽

The Magnetic Field

Abstract. Themis E observed a perpendicular (to the magnetic field) electric field associated with an Earthward plasma flow at XGSM=−9.6 RE on 11 January 2008. The electric field observation resembles Cluster observations closer to Earth in the auroral region. The fast plasma flow shared some characteristics with bursty bulk flows (BBFs) but did not meet the usual criteria in maximum velocity and duration to qualify as one. Themis C observed the same flow further downtail but Themis D, separated by only 1 RE in azimuthal direction from Themis E, did not. At the time of the electric field and ion flow event, the all-sky imager and ground-based magnetometer at Rankin Inlet observed Poleward Boundary Intensifications (PBIs) and a negative bay signature. None of the other Themis ground-based observatories recorded any significant auroral or magnetic field activity, indicating that this was a localized activity. The joint Themis in situ and ground-based observations suggest that the two observations are related. This indicates that auroral electric fields can extend to regions much farther out than previously seen in Cluster observations.

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Principal Component Gradiometer technique for removal of spacecraft-generated disturbances from magnetic field data

10.5194/gi-2020-10 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ovidiu Dragoş Constantinescu ◽

Hans-Ulrich Auster ◽

Magda Delva ◽

Olaf Hillenmaier ◽

Werner Magnes ◽

...

Keyword(s):

Magnetic Field ◽

Principal Component ◽

Field Measurements ◽

Magnetic Field Data ◽

Service Oriented ◽

Sensor Configuration ◽

Time Required ◽

First Time ◽

The Magnetic Field

Abstract. In situ measurement of the magnetic field using space borne instruments requires either a magnetically clean platform and/or a very long boom for accommodating magnetometer sensors at a large distance from the spacecraft body. This significantly drives up the costs and time required to build a spacecraft. Here we present an alternative sensor configuration and an algorithm allowing for ulterior removal of the spacecraft generated disturbances from the magnetic field measurements, thus lessening the need for a magnetic cleanliness program and allowing for shorter boom length. The proposed algorithm is applied to the Service Oriented Spacecraft Magnetometer (SOSMAG) onboard the Korean geostationary satellite GeoKompsat-2A (GK2A) which uses for the first time a multi-sensor configuration for onboard data cleaning. The successful elimination of disturbances originating from several sources validates the proposed cleaning technique.

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Transport of energetic particles from reconnecting current sheets in flaring corona to the heliosphere

10.5194/egusphere-egu21-15163 ◽

2021 ◽

Author(s):

Philippa Browning ◽

Mykola Gordovskyy ◽

Satashi Inoue ◽

Eduard Kontar ◽

Kanya Kusano ◽

...

Keyword(s):

Magnetic Field ◽

Energetic Particles ◽

Transport Processes ◽

Data Driven ◽

Current Sheets ◽

Electrons And Ions ◽

Data Driven Approach ◽

Particle Simulations ◽

The Magnetic Field

In this study, we inverstigate the acceleration of electrons and ions at current sheets in the flaring solar corona, and their transport into the heliosphere. We consider both generic solar flare models and specific flaring events with a data-driven approach. The aim is to answer two questions: (a) what fraction of particles accelerated in different flares can escape into the heliosphere?; and (b) what are the characteristics of the particle populations propagating towards the chromosphere and into the heliosphere?We use a combination of data-driven 3D magnetohydrodynamics simulations with drift-kinetic particle simulations to model the evolution of the magnetic field and both thermal and non-thermal plasma and to forward-model observable characteristics. Particles are accelerated in current sheets associated with flaring reconnection. When applied to a specific flare, the model successfully predicts observed features such as the location and relative intensity of hard X-ray sources and helioseismic source locations. This confirms the viability of the approach.Using these MHD-particle models, we will show how the magnetic field evolution and particle transport processes affect the characteristics of both energetic electrons and ions in the the inner corona and the heliosphere. The implications for interpretation of in situ measurements of energetic particles by Solar Orbiter and Parker Solar Probe will be discussed.&#160;&#160;

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Strong Southward and Northward Currents Observed in the Inner Plasma Sheet

10.5194/angeo-2019-56 ◽

2019 ◽

Author(s):

Yanyan Yang ◽

Chao Shen ◽

Yong Ji

Keyword(s):

Magnetic Field ◽

Plasma Sheet ◽

Ring Current ◽

Generation Mechanism ◽

Storm Events ◽

Current Generation ◽

Inner Magnetosphere ◽

Latitude Region ◽

Field Lines ◽

The Magnetic Field

Abstract. It is generally believed that field aligned currents (FACs) and the ring current (RC) are two dominant parts of the inner magnetosphere. However, using the Cluster spacecraft crossing of the pre-midnight inner plasma sheet in the latitude region between 10° N and 30° N, it is found that, during large storm events, in addition to FACs and the RC, there also exist strong southward and northward currents, which cannot be FACs, because the magnetic field in these regions is mainly along the XY plane. Detailed investigation shows that both magnetic field lines (MFLs) and currents in these regions highly fluctuate. When the curvature of MFLs changes direction in the XY plane, the current also alternatively switches between southward and northward. Further analysis of the current generation mechanism indicates that the most reasonable candidate for the origin of these southward and northward currents is the curvature drift of energetic particles.

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Observation of reconnection pulses by Cluster and Double Star

Annales Geophysicae ◽

10.5194/angeo-23-2921-2005 ◽

2005 ◽

Vol 23 (8) ◽

pp. 2921-2927 ◽

Cited By ~ 1

Author(s):

X. H. Deng ◽

R. X. Tang ◽

R. Nakamura ◽

W. Baumjohann ◽

T. L. Zhang ◽

...

Keyword(s):

Magnetic Field ◽

Energetic Electron ◽

Curvature Vector ◽

Double Star ◽

Neutral Sheet ◽

Inner Magnetosphere ◽

Point Analysis ◽

Earthward Flow ◽

Tailward Flow ◽

The Magnetic Field

Abstract. During a reconnection event on 7 August 2004, Cluster and Double Star (TC-1) were near the neutral sheet and simultaneously detected the signatures of the reconnection pulses. AT 22:59 UT tailward flow followed by earthward flow was detected by Cluster at about 15 RE, while earthward plasma flow followed by tailward flow was observed by TC-1 at about 10 RE. During the flow reversal from tailward to earthward, the magnetic field Bz changed sign from mainly negative values to positive, and the X component of the magnetic curvature vector switched sign from the tailward direction to the earthward direction, which indicates that the reconnection site (X-line) moved tailward past the Cluster constellation. By using multi-point analysis and observation of energetic electron and ion flux, we study the movement and structure of the current sheet and discuss the braking effect of the earthward flow bursts in the inner magnetosphere.

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Study of the applicability of the curlometer technique with the four Cluster spacecraft in regions close to Earth

Annales Geophysicae ◽

10.5194/angeo-30-597-2012 ◽

2012 ◽

Vol 30 (3) ◽

pp. 597-611 ◽

Cited By ~ 9

Author(s):

S. Grimald ◽

I. Dandouras ◽

P. Robert ◽

E. Lucek

Keyword(s):

Magnetic Field ◽

Current Density ◽

Ring Current ◽

Current System ◽

Sufficient Conditions ◽

Magnetic Activity ◽

Inner Magnetosphere ◽

Good Proxy ◽

The Magnetic Field ◽

Magnetospheric Current System

Abstract. Knowledge of the inner magnetospheric current system (intensity, boundaries, evolution) is one of the key elements for the understanding of the whole magnetospheric current system. In particular, the calculation of the current density and the study of the changes in the ring current is an active field of research as it is a good proxy for the magnetic activity. The curlometer technique allows the current density to be calculated from the magnetic field measured at four different positions inside a given current sheet using the Maxwell-Ampere's law. In 2009, the CLUSTER perigee pass was located at about 2 RE allowing a study of the ring current deep inside the inner magnetosphere, where the pressure gradient is expected to invert direction. In this paper, we use the curlometer in such an orbit. As the method has never been used so deep inside the inner magnetosphere, this study is a test of the curlometer in a part of the magnetosphere where the magnetic field is very high (about 4000 nT) and changes over small distances (ΔB = 1nT in 1000 km). To do so, the curlometer has been applied to calculate the current density from measured and modelled magnetic fields and for different sizes of the tetrahedron. The results show that the current density cannot be calculated using the curlometer technique at low altitude perigee passes, but that the method may be accurate in a [3 RE; 5 RE] or a [6 RE; 8.3 RE] L-shell range. It also demonstrates that the parameters used to estimate the accuracy of the method are necessary, but not sufficient conditions.

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Planar magnetic structures in coronal mass ejection-driven sheath regions

Annales Geophysicae ◽

10.5194/angeo-34-313-2016 ◽

2016 ◽

Vol 34 (2) ◽

pp. 313-322 ◽

Cited By ~ 27

Author(s):

Erika Palmerio ◽

Emilia K. J. Kilpua ◽

Neel P. Savani

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Coronal Mass Ejection ◽

Leading Edge ◽

Formation Mechanisms ◽

Single Plane ◽

Magnetic Structures ◽

Automated Method ◽

Mass Ejection ◽

The Magnetic Field

Abstract. Planar magnetic structures (PMSs) are periods in the solar wind during which interplanetary magnetic field vectors are nearly parallel to a single plane. One of the specific regions where PMSs have been reported are coronal mass ejection (CME)-driven sheaths. We use here an automated method to identify PMSs in 95 CME sheath regions observed in situ by the Wind and ACE spacecraft between 1997 and 2015. The occurrence and location of the PMSs are related to various shock, sheath, and CME properties. We find that PMSs are ubiquitous in CME sheaths; 85 % of the studied sheath regions had PMSs with the mean duration of 6 h. In about one-third of the cases the magnetic field vectors followed a single PMS plane that covered a significant part (at least 67 %) of the sheath region. Our analysis gives strong support for two suggested PMS formation mechanisms: the amplification and alignment of solar wind discontinuities near the CME-driven shock and the draping of the magnetic field lines around the CME ejecta. For example, we found that the shock and PMS plane normals generally coincided for the events where the PMSs occurred near the shock (68 % of the PMS plane normals near the shock were separated by less than 20° from the shock normal), while deviations were clearly larger when PMSs occurred close to the ejecta leading edge. In addition, PMSs near the shock were generally associated with lower upstream plasma beta than the cases where PMSs occurred near the leading edge of the CME. We also demonstrate that the planar parts of the sheath contain a higher amount of strong southward magnetic field than the non-planar parts, suggesting that planar sheaths are more likely to drive magnetospheric activity.

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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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Cleaning magnetometer data using multi sensor configuration

10.5194/egusphere-egu2020-17741 ◽

2020 ◽

Author(s):

Dragos Constantinescu ◽

Hans-Ulrich Auster ◽

Magda Delva ◽

Olaf Hillenmaier ◽

Werner Magnes ◽

...

Keyword(s):

Magnetic Field ◽

Field Measurements ◽

Sensor Arrangement ◽

Magnetometer Data ◽

Service Oriented ◽

Sensor Configuration ◽

First Time ◽

The Magnetic Field ◽

Magnetic Cleanliness

Measuring the in situ magnetic field using space borne instruments requires either a magnetically clean platform and/or a very long boom for accommodating magnetometers sensors at a large distance from the spacecraft body. This significantly drives up the costs and time for building the spacecraft. Here we present an alternative sensor configuration and an algorithm allowing for ulterior removing of the spacecraft generated disturbances from the magnetic field measurements, thus lessening the need for a magnetic cleanliness program.The Service Oriented Spacecraft Magnetometer (SOSMAG) onboard the Korean Geostationary Satellite GEO-KOMPSAT-2A (GK-2A) uses for the first time a multi-sensor configuration for onboard data cleaning. To remove the AC disturbances, a combination of the measurements from sensors placed at different positions from the disturbance sources is processed onboard. Sensor biases due to daily temperature variations are also removed using the specific SOSMAG sensor arrangement.&#160;&#160;

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