The asymmetric geospace response to rapid changes in solar wind pressure

2021 ◽  
Author(s):  
Michael Madelaire ◽  
Karl Laundal ◽  
Jone Reistad ◽  
Spencer Hatch ◽  
Anders Ohma ◽  
...  
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Interplanetary Shock ◽  
Wind Pressure ◽  
Field Orientation ◽  
Superposed Epoch Analysis ◽  
Rapid Changes ◽  
Solar Wind Structure ◽  
Solar Wind Pressure ◽  
The Impact

<p>The geospace response to rapid changes in solar wind pressure results in a perturbation of the magnetospheric-ionospheric system. Ground magnetometer stations located at polar latitudes have long been known to measure a sudden impulse only minutes after a solar wind structure reaches the magnetopause.<br>Here a list of events associated with a step-like feature in the solar wind dynamic pressure between 1994 and 2020 is compiled based on in situ observations from ACE and Wind. Arrival time estimates are calculated using a simple propagation method and validated with a correlation analysis using SYM-H from low/mid latitude stations. A superposed epoch analysis is carried out to investigate the impact of season, interplanetary magnetic field orientation and other attributes pertaining to the interplanetary shock. All available ground magnetometer stations in SuperMAG, during each event, are used allowing for global coverage. <br>Global data coverage is important for this kind of comparative analysis as it is needed to determine changes in the systems response due to e.g. season, which might lead to an improved understanding of the magnetospheric-ionospheric-thermospheric coupling.</p>

scholarly journals Cluster observations of sudden impulses in the magnetotail caused by interplanetary shocks and pressure increases

2005 ◽  
Vol 23 (2) ◽  
pp. 609-624 ◽  
Author(s):  
K. E. J. Huttunen ◽  
J. Slavin ◽  
M. Collier ◽  
H. E. J. Koskinen ◽  
A. Szabo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Dynamic Pressure ◽  
Solar Wind Speed ◽  
Interplanetary Shock ◽  
Wind Pressure ◽  
Shock Propagation ◽  
Interplanetary Shocks ◽  
Maximum Variance ◽  
The Magnetic Field

Abstract. Sudden impulses (SI) in the tail lobe magnetic field associated with solar wind pressure enhancements are investigated using measurements from Cluster. The magnetic field components during the SIs change in a manner consistent with the assumption that an antisunward moving lateral pressure enhancement compresses the magnetotail axisymmetrically. We found that the maximum variance SI unit vectors were nearly aligned with the associated interplanetary shock normals. For two of the tail lobe SI events during which Cluster was located close to the tail boundary, Cluster observed the inward moving magnetopause. During both events, the spacecraft location changed from the lobe to the magnetospheric boundary layer. During the event on 6 November 2001 the magnetopause was compressed past Cluster. We applied the 2-D Cartesian model developed by collier98 in which a vacuum uniform tail lobe magnetic field is compressed by a step-like pressure increase. The model underestimates the compression of the magnetic field, but it fits the magnetic field maximum variance component well. For events for which we could determine the shock normal orientation, the differences between the observed and calculated shock propagation times from the location of WIND/Geotail to the location of Cluster were small. The propagation speeds of the SIs between the Cluster spacecraft were comparable to the solar wind speed. Our results suggest that the observed tail lobe SIs are due to lateral increases in solar wind dynamic pressure outside the magnetotail boundary.

scholarly journals Magnetospheric Response to Solar Wind Forcing: ULF Wave – Particle Interaction Perspective

2021 ◽  
Author(s):  
Qiugang Zong
Keyword(s):  
Solar Wind ◽  
Radiation Belt ◽  
Ring Current ◽  
Dynamic Pressure ◽  
Plasma Heating ◽  
Interplanetary Shock ◽  
Wind Forcing ◽  
Ulf Waves ◽  
Radiation Belt Electrons ◽  
The Impact

Abstract. Solar wind forcing, e.g. interplanetary shock and/or solar wind dynamic pressure pulses impact on the Earth’s magnetosphere manifests many fundamental important space physics phenomena including producing electromagnetic waves, plasma heating and energetic particle acceleration. This paper summarizes our present understanding of the magnetospheric response to solar wind forcing in the aspects of radiation belt electrons, ring current ions and plasmaspheric plasma physics based on in situ spacecraft measurements, ground-based magnetometer data, MHD and kinetic simulations. Magnetosphere response to solar wind forcing, is not just a “one-kick” scenario. It is found that after the impact of solar wind forcing on the Earth’s magnetosphere, plasma heating and energetic particle acceleration started nearly immediately and could last for a few hours. Even a small dynamic pressure change of interplanetary shock or solar wind pressure pulse can play a non-negligible role in magnetospheric physics. The impact leads to generate series kind of waves including poloidal mode ultra-low frequency (ULF) waves. The fast acceleration of energetic electrons in the radiation belt and energetic ions in the ring current region response to the impact usually contains two contributing steps: (1) the initial adiabatic acceleration due to the magnetospheric compression; (2) followed by the wave-particle resonant acceleration dominated by global or localized poloidal ULF waves excited at various L-shells. Generalized theory of drift and drift-bounce resonance with growth or decay localized ULF waves has been developed to explain in situ spacecraft observations. The wave related observational features like distorted energy spectrum, boomerang and fishbone pitch angle distributions of radiation belt electrons, ring current ions and plasmaspheric plasma can be explained in the frame work of this generalized theory. It is worthy to point out here that poloidal ULF waves are much more efficient to accelerate and modulate electrons (fundamental mode) in the radiation belt and charged ions (second harmonic) in the ring current region. The results presented in this paper can be widely used in solar wind interacting with other planets such as Mercury, Jupiter, Saturn, Uranus and Neptune, and other astrophysical objects with magnetic fields.

scholarly journals Induced and Permanent Magnetism on the Moon: Structural and Evolutionary Implications

1971 ◽  
Vol 2 ◽  
pp. 173-188
Author(s):  
C. P. Sonett ◽  
P. Dyal ◽  
D. S. Colburn ◽  
B. F. Smith ◽  
G. Schubert ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Dynamic Pressure ◽  
Wind Pressure ◽  
Dark Side ◽  
The Moon ◽  
Permanent Magnetic Field ◽  
Crustal Layer ◽  
Induced Field ◽  
Solar Wind Pressure

AbstractIt is shown that the Moon possesses an extraordinary response to induction from the solar wind due to a combination of a high interior electrical conductivity together with a relatively resistive crustal layer into which the solar wind dynamic pressure forces back the induced field. The dark side response, devoid of solar wind pressure, is approximately that expected for the vacuum case. These data permit an assessment of the interior conductivity and an estimate of the thermal gradient in the crustal region. The discovery of a large permanent magnetic field at the Apollo 12 site corresponds approximately to the paleomagnetic residues discovered in both Apollo 11 and 12 rock samples The implications regarding an early lunar magnetic field are discussed and it is shown that among the various conjectures regarding the early field the most prominent are either an interior dynamo or an early approach to the Earth though no extant model is free of difficulties.

Effects of the solar wind dynamic pressure on the accelerated cometary ions in the magnetosphere of comet 67P

2020 ◽  
Author(s):  
Aniko Timar ◽  
Zoltan Nemeth ◽  
Karoly Szego ◽  
Melinda Dósa ◽  
Balazs Nagy
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Dynamic Spectrum ◽  
Low Energy ◽  
Wind Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Medium Energy ◽  
Solar Wind Pressure ◽  
The Relationship ◽  
Comet 67P

<p>Rosetta observed medium-energy ions around comet 67P/Churyumov-Gerasimenko while orbiting deep inside the coma. These ions are thought to be accelerated towards the anti-sunward direction by some acceleration mechanism in the outer regions of the cometary magnetosphere. They usually reach energies up to 100-1000 eV and undergo deceleration in the dense neutral coma surrounding the nucleus. These ions usually appear in the ion dynamic spectrum as a new population rising from the low energy background, their energy peaking around 1000 eV and then decreasing until the population disappears again. We investigated the properties of these ions, as well as the relationship between the solar wind pressure and the energy of the medium-energy ions to discover the cause of the observed time variation. We show that there is a correlation between the solar wind dynamic pressure around the comet and the energy of the accelerated ions.</p>

Magnetospheric Response to Solar Wind Forcing: ULF Waves – Particle interaction Perspective 

2021 ◽  
Author(s):  
Qiugang Zong
Keyword(s):  
Solar Wind ◽  
Radiation Belt ◽  
Ring Current ◽  
Dynamic Pressure ◽  
Plasma Heating ◽  
Interplanetary Shock ◽  
Wind Forcing ◽  
Ulf Waves ◽  
Radiation Belt Electrons ◽  
The Impact

<p>Solar wind forcing, e.g. interplanetary shock and/or solar wind dynamic pressure pulses impact on the Earth’s magnetosphere manifests many fundamental important space physics phenomena including producing electromagnetic waves, plasma heating and energetic particle acceleration. This paper summarizes our present understanding of the magnetospheric response to solar wind forcing in the aspects of radiation belt electrons, ring current ions and plasmaspheric plasma physic based on in situ spacecraft measurements, ground-based magnetometer data, MHD and kinetic simulations.</p><p>Magnetosphere response to solar wind forcing, is not just “one-kick” scenario. It is found that after the impact of solar wind forcing on the Earth’s magnetosphere, plasma heating and energetic particle acceleration started nearly immediately and could last for a few hours. Even a small dynamic pressure change of interplanetary shock or solar wind pressure pulse can play a non-negligible role in magnetospheric physics. The impact leads to generate series kind of waves including poloidal mode ultra-low frequency (ULF) waves. The fast acceleration of energetic electrons in the radiation belt and energetic ions in the ring current region response to the impact usually contain two contributing steps: (1) the initial adiabatic acceleration due to the magnetospheric compression; (2) followed by the wave-particle resonant acceleration dominated by global or localized poloidal ULF waves excited at various L-shells.</p><p>Generalized theory of drift and drift-bounce resonance with growth or decay localized ULF waves have been developed to explain in situ spacecraft observations. The wave related observational features like distorted energy spectrum, boomerang and fishbone pitch angle distributions of radiation belt electrons, ring current ions and plasmaspheric plasma can be explained in the frame work of this generalized theory. It is worthy to point out here that poloidal ULF wave is much more efficient to accelerate and modulate electrons (fundamental mode) in the radiation belt and charged ions (second harmonic) in the ring current region. The results presented in this paper can be widely used in solar wind interacting with other planets such as Mercury, Jupiter, Saturn, Uranus and Neptune, and other astrophysical objects with magnetic fields.</p>

scholarly journals Geomagnetic field fluctuations during the passage at the Earth’s orbit of the tail of the 15–16 July 2000 ejecta

2002 ◽  
Vol 20 (8) ◽  
pp. 1143-1152 ◽  
Author(s):  
P. Francia ◽  
S. Lepidi ◽  
K. Yumoto
Keyword(s):  
Solar Wind ◽  
Local Time ◽  
Geomagnetic Field ◽  
Dynamic Pressure ◽  
Recovery Phase ◽  
Wind Pressure ◽  
Mhd Waves ◽  
Time Interval ◽  
Field Fluctuations ◽  
Solar Wind Pressure

Abstract. In this work we present the analysis of the geomagnetic field fluctuations observed at different ground stations (approximately along two latitudinal arrays, separated by several hours in local time) during the passage at the Earth’s orbit of the tail of the 15–16 July 2000 coronal ejecta. The time interval of interest is characterized by northward interplanetary magnetic field conditions and several changes in the solar wind dynamic pressure. We found at all stations, both in the local morning and in the local evening, simultaneous and highly coherent waves at the same discrete frequencies (~ 1.8 and ~ 3.6 mHz) and suggest a possible interpretation in terms of global compressional modes driven by an impulsive variation of the solar wind pressure. Along the array situated in the morning sector, at the highest latitudes, the higher frequency mode seems to couple with the local field line resonance; on the other hand, along the array situated in the evening sector, the characteristics of the observed fluctuations suggest that the highest latitude station could be located at the footprint of open field lines. Our results also show that solar wind pressure variations observed during the recovery phase of the storm do not find correspondence in the geomagnetic field variations, regardless of local time and latitude; conversely, some hours later continuous solar wind pressure variations find a close correspondence in the geomagnetic field variations at all stations.Key words. Magnetospheric physics (solar wind-magnetosphere interaction; MHD waves and instabilities)

scholarly journals On the excitation of ULF waves by solar wind pressure enhancements

2006 ◽  
Vol 24 (11) ◽  
pp. 3161-3172 ◽  
Author(s):  
P. T. I. Eriksson ◽  
L. G. Blomberg ◽  
S. Schaefer ◽  
K.-H. Glassmeier
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Travelling Waves ◽  
Low Frequency ◽  
Compressional Wave ◽  
Wave Mode ◽  
Wind Pressure ◽  
Wave Number ◽  
Toroidal Mode ◽  
Solar Wind Pressure

Abstract. We study the onset and development of an ultra low frequency (ULF) pulsation excited by a storm sudden commencement. On 30 August 2001, 14:10 UT, the Cluster spacecraft are located in the dayside magnetosphere and observe the excitation of a ULF pulsation by a threefold enhancement in the solar wind dynamic pressure. Two different harmonics are observed by Cluster, one at 6.8 mHz and another at 27 mHz. We observe a compressional wave and the development of a toroidal and poloidal standing wave mode. The toroidal mode is observed over a narrow range of L-shells whereas the poloidal mode is observed to have a much larger radial extent. By looking at the phase difference between the electric and magnetic fields we see that for the first two wave periods both the poloidal and toroidal mode are travelling waves and then suddenly change into standing waves. We estimate the azimuthal wave number for the 6.8 mHz to be m=10±3. For the 27 mHz wave, m seems to be several times larger and we discuss the implications of this. We conclude that the enhancement in solar wind pressure excites eigenmodes of the geomagnetic cavity/waveguide that propagate tailward and that these eigenmodes in turn couple to toroidal and poloidal mode waves. Thus our observations give firm support to the magnetospheric waveguide theory.

Photometry of dayside auroras during solar minimum 1This article is part of a Special issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

2012 ◽  
Vol 90 (8) ◽  
pp. 753-758 ◽  
Author(s):  
D.J. McEwen ◽  
G.G. Sivjee
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Solar Minimum ◽  
Dynamic Pressure ◽  
Wind Pressure ◽  
Special Issue ◽  
Solar Wind Pressure ◽  
The Many ◽  
Airglow Intensity

An examination is made of Antarctic dayside auroras to establish how they relate to solar wind strength under the quiet conditions of the recent extended solar minimum when the solar wind pressure was weak and the interplanetary magnetic field Bz is small. It is found that, during the many days of observation, the aurora is detected even with the most stable and quiet conditions. On such occasions the 630 nm OI emission can be as low as 50 R, but is unambiguously and continuously detectable through each noon. This is above an airglow intensity of about 30 R. For these quiet conditions there is no evident relation between the solar wind dynamic pressure or interplanetary magnetic field Bz and dayside auroral intensity. This suggests that there is no effective reconnection under these minimal conditions and the particle source for the dayside aurora could be within the magnetosphere.

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