scholarly journals Origin of Solar Rotational Periodicity and Harmonics Identified in the Interplanetary Magnetic Field B z $B_{z}$ Component Near the Earth During Solar Cycles 23 and 24

Solar Physics ◽  
2019 ◽  
Vol 294 (4) ◽  
Author(s):  
Kyung-Eun Choi ◽  
Dae-Young Lee
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Solar Cycles ◽  
The Earth

scholarly journals Cellular automata model of magnetospheric-ionospheric coupling

2003 ◽  
Vol 21 (9) ◽  
pp. 1931-1938 ◽  
Author(s):  
B. V. Kozelov ◽  
T. V. Kozelova
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cellular Automata ◽  
Interplanetary Magnetic Field ◽  
Control Parameter ◽  
Energy Content ◽  
Nonlinear Phenomena ◽  
Cellular Automata Model ◽  
The Earth ◽  
Magnetospheric Tail

Abstract. We propose a cellular automata model (CAM) to describe the substorm activity of the magnetospheric-ionospheric system. The state of each cell in the model is described by two numbers that correspond to the energy content in a region of the current sheet in the magnetospheric tail and to the conductivity of the ionospheric domain that is magnetically connected with this region. The driving force of the system is supposed to be provided by the solar wind that is convected along the two boundaries of the system. The energy flux inside is ensured by the penetration of the energy from the solar wind into the array of cells (magnetospheric tail) with a finite velocity. The third boundary (near to the Earth) is closed and the fourth boundary is opened, thereby modeling the flux far away from the tail. The energy dissipation in the system is quite similar to other CAM models, when the energy in a particular cell exceeds some pre-defined threshold, and the part of the energy excess is redistributed between the neighbouring cells. The second number attributed to each cell mimics ionospheric conductivity that can allow for a part of the energy to be shed on field-aligned currents. The feedback between "ionosphere" and "magnetospheric tail" is provided by the change in a part of the energy, which is redistributed in the tail when the threshold is surpassed. The control parameter of the model is the z-component of the interplanetary magnetic field (Bz IMF), "frozen" into the solar wind. To study the internal dynamics of the system at the beginning, this control parameter is taken to be constant. The dynamics of the system undergoes several bifurcations, when the constant varies from - 0.6 to - 6.0. The Bz IMF input results in the periodic transients (activation regions) and the inter-transient period decreases with the decrease of Bz. At the same time the onset of activations in the array shifts towards the "Earth". When the modulus of the Bz IMF exceeds some threshold value, the transition takes place from periodic to chaotic dynamics. In the second part of the work we have chosen as the source the real values of the z-component of the interplanetary magnetic field taken from satellite observations. We have shown that in this case the statistical properties of the transients reproduce the characteristic features observed by Lui et al. (2000).Key words. Magnetospheric physics (magnetosphere-ionosphere interactions) – Space plasma physics (nonlinear phenomena)

scholarly journals Jets in the Magnetosheath: IMF Control of Where They Occur

2019 ◽  
Author(s):  
Laura Vuorinen ◽  
Heli Hietala ◽  
Ferdinand Plaschke
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Spatial Distribution ◽  
Interplanetary Magnetic Field ◽  
Cone Angle ◽  
Time History ◽  
Bow Shock ◽  
The Earth ◽  
Parallel Side ◽  
History Of

Abstract. Magnetosheath jets are localized regions of plasma that move faster towards the Earth than the surrounding magnetosheath plasma. Due to their high velocities, they can cause indentations when colliding into the magnetopause and trigger processes such as magnetic reconnection and magnetopause surface waves. We statistically study the occurrence of these jets in the subsolar magnetosheath using measurements from the five Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and OMNI solar wind data from 2008–2011. We present the observations in the BIMF-vSW plane and study the spatial distribution of jets during different interplanetary magnetic field (IMF) orientations. Jets occur downstream of the quasi-parallel bow shock approximately 9 times as often as downstream of the quasi-perpendicular shock, suggesting that foreshock processes are responsible for most jets. For oblique IMF, with 30°–60° cone angle, the occurrence increases monotonically from the quasi-perpendicular side to the quasi-parallel side. This study offers predictability for the numbers and locations of jets observed during different IMF orientations allowing us to better forecast the formation of these jets and their impact on the magnetosphere.

scholarly journals Solar Cycle Variation of Cosmic ray Intensity along with Interplanetary and Solar Wind Plasma Parameters

2008 ◽  
Vol 45 (3) ◽  
pp. 63-68 ◽  
Author(s):  
Rajesh Mishra ◽  
Rekha Agarwal ◽  
Sharad Tiwari
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Cosmic Ray ◽  
Solar Wind Plasma ◽  
Solar Cycles ◽  
Plasma Parameters ◽  
Solar Cycle Variation ◽  
Cosmic Ray Intensity

Solar Cycle Variation of Cosmic ray Intensity along with Interplanetary and Solar Wind Plasma ParametersGalactic cosmic rays are modulated at their propagation in the heliosphere by the effect of the large-scale structure of the interplanetary medium. A comparison of the variations in the cosmic ray intensity data obtained by neutron monitoring stations with those in geomagnetic disturbance, solar wind velocity (V), interplanetary magnetic field (B), and their product (V' B) near the Earth for the period 1964-2004 has been presented so as to establish a possible correlation between them. We used the hourly averaged cosmic ray counts observed with the neutron monitor in Moscow. It is noteworthy that a significant negative correlation has been observed between the interplanetary magnetic field, product (V' B) and cosmic ray intensity during the solar cycles 21 and 22. The solar wind velocity has a good positive correlation with cosmic ray intensity during solar cycle 21, whereas it shows a weak correlation during cycles 20, 22 and 23. The interplanetary magnetic field shows a weak negative correlation with cosmic rays for solar cycle 20, and a good anti-correlation for solar cycles 21-23 with the cosmic ray intensity, which, in turn, shows a good positive correlation with disturbance time index (Dst) during solar cycles 21 and 22, and a weak correlation for cycles 20 and 23.

scholarly journals The mean solar magnetic field as an indicator of the interplanetary magnetic field

1996 ◽  
Vol 39 (4) ◽  
Author(s):  
J. Bremer
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Structure Data ◽  
Solar Magnetic Field ◽  
Private Communication ◽  
Sector Structure ◽  
Ionospheric Effect ◽  
Ionospheric Response ◽  
The Earth ◽  
The Mean

The Mean Solar Magnetic Field (MSMF) measured daily by ground based observations at the Standford Observatory shows similar structures like the Interplanetary Magnetic Field (IMF) near the Earth about 5 to 7 days later. The ionospheric effect in the mid-latitude F2-region due to such MSMF changes is most marked for strong MSMF changes from anti to pro sectors. The mean ionospheric response is very similar to the results obtained earlier with IMF sector structure data derived from Svalgaard (1976) and Wilcox (1982, private communication). Therefore, the MSMF data can successfully be used to predict the mean IMF sector structure and the mean ionospheric response 5 to 7 days in advance.

Extreme event theory applied to the solar wind

2021 ◽  
Author(s):  
Carlos Larrodera ◽  
Lidia Nikitina ◽  
Consuelo Cid
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Space Weather ◽  
Extreme Event ◽  
Extreme Value Distribution ◽  
Value Theory ◽  
Extreme Value ◽  
Parameter Analysis ◽  
Solar Cycles

<p>Society’s dependence on technology has increased during the past years. Therefore, understanding the hazardous events including space weather events that lead to technological problems is now critical. As solar wind is the driver of space weather, identifying extreme solar wind is important. In this work extreme value theory is used to characterize the solar wind parameters most relevant to space weather: interplanetary magnetic field strength and proton speed. This is done using an extreme value distribution for all data above a certain threshold for each parameter. Analysis demonstrates that these thresholds are around 900 km/s for the proton speed and around 95 nT for the interplanetary magnetic field. Based on 20 years of solar wind data, we made an estimation for the interplanetary magnetic field and solar wind proton speed with return periods corresponding to 4 and 6 solar cycles with a 99% confidence interval.</p>

scholarly journals Jets in the magnetosheath: IMF control of where they occur

2019 ◽  
Vol 37 (4) ◽  
pp. 689-697 ◽  
Author(s):  
Laura Vuorinen ◽  
Heli Hietala ◽  
Ferdinand Plaschke
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Spatial Distribution ◽  
Interplanetary Magnetic Field ◽  
Cone Angle ◽  
Time History ◽  
Bow Shock ◽  
The Earth ◽  
Parallel Side ◽  
History Of

Abstract. Magnetosheath jets are localized regions of plasma that move faster towards the Earth than the surrounding magnetosheath plasma. Due to their high velocities, they can cause indentations when colliding into the magnetopause and trigger processes such as magnetic reconnection and magnetopause surface waves. We statistically study the occurrence of these jets in the subsolar magnetosheath using measurements from the five Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and OMNI solar wind data from 2008 to 2011. We present the observations in the BIMF–vSW plane and study the spatial distribution of jets during different interplanetary magnetic field (IMF) orientations. Jets occur downstream of the quasi-parallel bow shock approximately 9 times as often as downstream of the quasi-perpendicular shock, suggesting that foreshock processes are responsible for most jets. For an oblique IMF, with 30–60∘ cone angle, the occurrence increases monotonically from the quasi-perpendicular side to the quasi-parallel side. This study offers predictability for the numbers, locations, and magnetopause impact rates of jets observed during different IMF orientations, allowing us to better forecast the formation of these jets and their impact on the magnetosphere.

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