scholarly journals North-south asymmetry of geomagnetic activity and solar wind electric field

2016 ◽  
Vol 2 (1) ◽  
pp. 32-35
Author(s):  
Георгий Макаров ◽  
Georgy Makarov
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Geomagnetic Activity ◽  
Daily Variation ◽  
Magnetic Activity ◽  
Qualitative Model ◽  
Low Latitudes ◽  
The Asymmetry ◽  
South Asymmetry ◽  
Northern And Southern Hemispheres

Geomagnetic activity asymmetry in the northern and southern hemispheres is studied. It is shown, that the higher is the level of magnetic activity the greater is asymmetry. It is found, that the asymmetry of hemispheres shows itself in the 06–18-hourly component of magnetic activity daily variation, while the asymmetry in the 00–12-hourly component is completely absent. The cause of geomagnetic north-south asymmetry is supposed to be Pedersen meridional current between high and low latitudes in the ionosphere. The qualitative model of formation of asymmetry connected with the solar wind electric field is proposed.

scholarly journals North-south asymmetry of geomagnetic activity and solar wind electric field

2016 ◽  
Vol 2 (1) ◽  
pp. 44-49
Author(s):  
Георгий Макаров ◽  
Georgy Makarov
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Diurnal Variation ◽  
Geomagnetic Activity ◽  
Magnetic Activity ◽  
Qualitative Model ◽  
Middle Latitudes ◽  
The Asymmetry ◽  
South Asymmetry ◽  
Northern And Southern Hemispheres

Geomagnetic activity asymmetry in the Northern and Southern hemispheres is studied. It is shown that the higher is the level of magnetic activity the greater is the asymmetry. It is found that the asymmetry in the hemispheres manifests itself in the 06–18-hour component of magnetic activity diurnal variation, while the asymmetry in the 00–12-hourly component is completely absent. The cause of geomagnetic north-south asymmetry is supposed to be meridional Pedersen current between high and middle latitudes in the ionosphere. A qualitative model of formation of asymmetry connected with the solar wind electric field is proposed.

K indices and K-derived magnetic activity indices:  context’s reminder

2021 ◽  
Author(s):  
Aude Chambodut
Keyword(s):  
Geomagnetic Activity ◽  
Daily Variation ◽  
Geomagnetic Latitude ◽  
Magnetic Activity ◽  
Geomagnetic Disturbances ◽  
K Index ◽  
Objective Monitoring ◽  
Magnetic Observatories ◽  
Activity Indices

<p>The K index was devised by Bartels et al. (1939) to provide an objective monitoring of irregular geomagnetic activity at subauroral latitudes. K indices are based upon geomagnetic disturbances, measured in horizontal geomagnetic components at magnetic observatories, after « eliminating » the regular daily variation. An individual K index is an integer in the range 0 to 9 corresponding to a class that contains the largest range of geomagnetic disturbances (in either of the two horizontal components) during a 3-hour UT interval. Limits of range vary from one observatory to another since they depend on the corrected geomagnetic latitude of the observatory.</p><p>A great number of Space Weather applications rely on K-derived magnetic activity indices at subauroral latitudes. These historical indices; endorsed by IAGA such as Kp, aa and am; represent unprecedented homogeneous time series, up to more than 150 years, highly valuable for all studies related to long-term geomagnetic activity.</p><p>However, one has to keep in mind that local K indices and subauroral related ones (K-derived) were developed during other time, under specific societal and technological conditions.</p><p>We recall the local K indices derivation processes and characteristics to enlight possible nowadays drawbacks and their simple mitigations.</p>

scholarly journals Invariability of relationship between the polar cap magnetic activity and geoeffective interplanetary electric field

2011 ◽  
Vol 29 (8) ◽  
pp. 1479-1489 ◽  
Author(s):  
O. A. Troshichev ◽  
N. A. Podorozhkina ◽  
A. S. Janzhura
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Electric Field ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Magnetic Activity ◽  
Polar Cap ◽  
Polar Caps ◽  
The Relationship ◽  
Wind Energy Input

Abstract. The PC (polar cap) index characterizing the solar wind energy input into the magnetosphere is calculated with use of parameters α, β, and φ, determining the relationship between the interplanetary electric field (EKL) and the value of magnetic activity δF in the polar caps. These parameters were noted as valid for large and small EKL values, and as a result the suggestion was made (Troshichev et al., 2006) that the parameters should remain invariant irrespective of solar activity. To verify this suggestion, the independent sets of calibration parameters α, β, and φ were derived separately for the solar maximum (1998–2001) and solar minimum (1997, 2007–2009) epochs, with a proper choice of a quiet daily variation (QDC) as a level of reference for the polar cap magnetic activity value. The results presented in this paper demonstrate that parameters α, β, and φ, derived under conditions of solar maximum and solar minimum, are indeed in general conformity and provide consistent (within 10 % uncertainty) estimations of the PC index. It means that relationship between the geoeffective solar wind variations and the polar cap magnetic activity responding to these variations remains invariant irrespective of solar activity. The conclusion is made that parameters α, β, and φ derived in AARI#3 version for complete cycle of solar activity (1995–2005) can be regarded as forever valid.

scholarly journals Dawn-dusk asymmetry in particles of solar wind origin within the magnetosphere

2001 ◽  
Vol 19 (1) ◽  
pp. 1-9 ◽  
Author(s):  
T. J. Stubbs ◽  
M. Lockwood ◽  
P. Cargill ◽  
J. Fennell ◽  
M. Grande ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Lower Energy ◽  
Closed Field ◽  
Fermi Acceleration ◽  
Ion Composition ◽  
Convection Electric Field ◽  
Magnetospheric Configuration And Dynamics ◽  
The Asymmetry ◽  
Curvature Gradient

Abstract. Solar wind/magnetosheath plasma in the magnetosphere can be identified using a component that has a higher charge state, lower density and, at least soon after their entry into the magnetosphere, lower energy than plasma from a terrestrial source. We survey here observations taken over 3 years of He2+ ions made by the Magnetospheric Ion Composition Sensor (MICS) of the Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) instrument aboard POLAR. The occurrence probability of these solar wind ions is then plotted as a function of Magnetic Local Time (MLT) and invariant latitude (7) for various energy ranges. For all energies observed by MICS (1.8–21.4 keV) and all solar wind conditions, the occurrence probabilities peaked around the cusp region and along the dawn flank. The solar wind conditions were filtered to see if this dawnward asymmetry is controlled by the Svalgaard-Mansurov effect (and so depends on the BY component of the interplanetary magnetic field, IMF) or by Fermi acceleration of He2+ at the bow shock (and so depends on the IMF ratio BX /BY ). It is shown that the asymmetry remained persistently on the dawn flank, suggesting it was not due to effects associated with direct entry into the magnetosphere. This asymmetry, with enhanced fluxes on the dawn flank, persisted for lower energy ions (below a "cross-over" energy of about 23 keV) but reversed sense to give higher fluxes on the dusk flank at higher energies. This can be explained by the competing effects of gradient/curvature drifts and the convection electric field on ions that are convecting sunward on re-closed field lines. The lower-energy He2+ ions E × B drift dawnwards as they move earthward, whereas the higher energy ions curvature/ gradient drift towards dusk. The convection electric field in the tail is weaker for northward IMF. Ions then need less energy to drift to the dusk flank, so that the cross-over energy, at which the asymmetry changes sense, is reduced.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; magnetopause, cusp, and boundary layers) – Space plasma physics (charged particle motion and acceleration)

scholarly journals Solar Wind Parameters and Its Geoefficiency During Minimums of Four Solar Cycles

2021 ◽  
Vol 31 (4) ◽  
pp. 508-514
Author(s):  
Vitalii Degtyarev ◽  
Georgy Popov ◽  
Svetlana Chudnenko
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Activity ◽  
Geomagnetic Activity ◽  
Statistical Processing ◽  
Magnetic Activity ◽  
Solar Cycles ◽  
Deep Minimum ◽  
Significant Difference ◽  
Solar Wind Parameters

Recently a number of publications have appeared on the long and deep minimum in cycle 23 of solar activity. This interest is due to the fact that it turned out to be the longest and deepest in terms of the number of sunspots in the entire era of space exploration. The features of the minimum of cycle 23 of solar activity and the beginning of cycle 24 made it possible to assume that in the coming decades, a minimum of solar activity similar to the Dalton or Maunder minimum, leading to a global change in the earth's climate, may occur. Such assumptions make a detailed study of the influence of the minimum of solar cycle 23 on the parameters of the solar wind and the interplanetary magnetic field, as well as a comparison of this influence with similar manifestations in the three previous cycles very urgent. The work carried out statistical processing and analysis of data available in print and on the Internet on the indices of solar activity (W and F10.7), on geomagnetic activity, as well as on the parameters of the solar wind and interplanetary field. In contrast to other similar studies, when choosing time intervals for all cycles, only one — 12 months was used, which made it possible to exclude annual and semi-annual variations in solar wind parameters. For the considered minima of solar activity, the geoeffectiveness of the disturbed fluxes ICME, CIR, and Sheath was considered. A monotonic and very significant decrease in the geoeffectiveness of the ICME streams was found. Data processing on the hourly average values of the solar wind parameters at the minima of geomagnetic activity for 4 cycles confirmed the significant difference between cycle 23 and the previous ones in the behavior of the magnetic field. The cycle-by-cycle decrease in the geoeffectiveness of coronal ejections discussed in the press deserves a more detailed analysis using extensive data on magnetic activity indices.

A software-computational neural network tool for predicting the electromagnetic state of the polar magnetosphere, taking into account the process that simulates its slow loading by the kinetic energy of the solar wind

2021 ◽  
Author(s):  
NIKOLAY BARKHATOV ◽  
SERGEY REVUNOV
Keyword(s):  
Solar Wind ◽  
Geomagnetic Activity ◽  
Magnetic Activity ◽  
Integral Parameter ◽  
Magnetospheric Substorms ◽  
Wide Range ◽  
Close Relationship ◽  
High Latitude Ionosphere ◽  
Western Electric ◽  
Intellectual Properties

The auroral activity indices AU, AL, AE, introduced into geophysics at the beginning of the space era, although they have certain drawbacks, are still widely used to monitor geomagnetic activity at high latitudes. The AU index reflects the intensity of the eastern electric jet, while the AL index is determined by the intensity of the western electric jet. There are many regression relationships linking the indices of magnetic activity with a wide range of phenomena observed in the Earth's magnetosphere and atmosphere. These relationships determine the importance of monitoring and predicting geomagnetic activity for research in various areas of solar-terrestrial physics. The most dramatic phenomena in the magnetosphere and high-latitude ionosphere occur during periods of magnetospheric substorms, a sensitive indicator of which is the time variation and value of the AL index. Currently, AL index forecasting is carried out by various methods using both dynamic systems and artificial intelligence. Forecasting is based on the close relationship between the state of the magnetosphere and the parameters of the solar wind and the interplanetary magnetic field (IMF). This application proposes an algorithm for describing the process of substorm formation using an instrument in the form of an Elman-type ANN by reconstructing the AL index using the dynamics of the new integral parameter we introduced. The use of an integral parameter at the input of the ANN makes it possible to simulate the structure and intellectual properties of the biological nervous system, since in this way an additional realization of the memory of the prehistory of the modeled process is provided.

Low and middle latitude thermosphere and ionosphere responses to geomagnetic activity

2021 ◽  
Author(s):  
Wenbin Wang ◽  
Qian Wu ◽  
Dong Ling
Keyword(s):  
Solar Wind ◽  
Electric Fields ◽  
Geomagnetic Activity ◽  
Middle Latitude ◽  
High Latitudes ◽  
Satellite Mission ◽  
Neutral Winds ◽  
Low Latitudes ◽  
Energy And Momentum ◽  
Induced Changes

<p>Solar wind and its embedded interplanetary magnetic field (IMF) affects Earth’s upper atmosphere by changing high-latitude ionospheric convection patter, producing auroral precipitation and depositing energy and momentum at high latitudes. These processes are greatly enhanced during geomagnetically active periods.  The geomagnetic activity induced changes at high latitudes are then transmitted to middle and low latitudes. In this work we employ the recently developed Multiscale Atmosphere-Geospace Environment (MAGE) model to simulate the non-linear electrodynamic and dynamic processes by which solar wind and IMF affect low and middle latitude thermosphere and ionosphere during geomagnetically active periods, including the stream interaction region event that happened in September 2020.  We examine the changes in ionospheric electric fields caused by penetration electric fields and neutral wind dynamo, as well as changes in neutral winds, temperature, composition  and ionospheric plasma densities. Model results are compared with  data from recent satellite mission, including COSMIC 2, GOLD and ICON to obtain new insight in the physical processes in the global thermosphere ionosphere responses to disturbed solar wind and IMF driving conditions.</p>

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