Geomagnetic Field Disturbances Research Articles

Classification of Solar Plasma Flows by Analyzing Out- and Intra-Magnetospheric Magnetohydrodynamic Oscillations During Magnetic Storms

Comparison of wavelet spectrum (skeletons) local maxima for disturbed components of solar plasma flow parameters and geomagnetic field disturbances recorded along the meridional station chain during geomagnetic storm intervals is performed in the range of magnetohydrodynamic (MHD) waves. An algorithm for quantitative evaluation of analyzed skeletons consistency has been developed. It has been used to demonstrate the possibility of the type of solar wind plasma flow elaboration on unique spectral signs of Solar wind speed disturbances, density and interplanetary magnetic field. It is shown that the energy spectrum of oscillations for these parameters reflects the internal structure of the corresponding plasma formation. The skeletons application to the analysis of the interplanetary space main parameters made it possible to estimate the magnetosphere reaction time in geomagnetic field horizontal component oscillations at different latitudes on the disturbance. As a result, the distributed magnetosphere reaction over latitude was determined in the form of geomagnetic field oscillations on the disturbed solar flow parameters. It is shown that the dynamics of the components of the solar wind parameters disturbance spectra corresponding to plasma flows manifest themselves in the MHD spectra of high-latitude stations magnetograms and can be used as a diagnostic tool.

Global response of Magnetic field and Ionosonde observations to intense solar flares on 6 and 10 September 2017

Intense X-ray fluxes during solar flares are known to cause enhanced ionization in the Earth’s ionospheric D, E and F region. This sudden change of ionospheric electron density profile is serious problem to radio wave communication and navigation system. The ground magnetograms often record the sudden change in the sunlit hemisphere during the enhanced X-ray flux, due to the sudden increase in the global ionospheric current system caused by the flare-induced enhanced ionospheric conductivity. These geomagnetic field disturbances are known as ‘‘solar flare effects’’ (SFEs) or geomagnetic crochets [Campbell, 2003]. The typical SFE is increase variation on the equatorial magnetic data. On Ionosonde observation during solar flare event, the High-Frequency (HF) radio wave blackout is often detected in ionogram due to the sudden disturbance in ionosphere. Two intense X-class solar flares occurred on 6 and 10 September 2017. We investigated the magnetic field and Ionosonde responses to the intense solar flare events. Dayside magnetic field variations sudden increased due to the ionospheric disturbance resulting from solar flare. There is no response in night side magnetometer data. The magnitude of SFE (magnetic field) is independent of solar flare x-ray magnitude. We found HF radio wave blackout in ionogram at dayside Ionosonde stations. The duration of blackout is dependent of latitude and local time of Ionosonde stations. There is the different feature of ionogram at night side.

Geomagnetic Field Disturbances Caused by Heliospheric Current Sheet Crossings

The heliospheric current sheet (HCS) is modified by the solar activity. HCS is highly inclined during solar maximum and almost confined with the solar equatorial plane during solar minimum. Close to the HCS solar wind parameters as proton temperature, flow speed, proton density, etc. differ compared to the region far from the HCS. The Earth’s magnetic dipole field crosses HCS several times each month. Considering interplanetary coronal mass ejections (ICME) and high speed solar wind streams (HSS) free periods an investigation of the HCS influence on the geomagnetic field disturbances is presented. The results show a drop of the Dst index and a rise of the AE index at the time of the HCS crossings and also that the behavior of these indices does not depend on the magnetic polarity.

Anomalous effects of radioactive decay rates and capacitance values measured inside a modified Faraday cage: Correlations with space weather

Recently we reported (Milián-Sánchez V. et al., Nucl. Instrum. Methods A, 828 (2016) 210) our experimental results involving 226Ra decay rate and capacitance measurements inside a modified Faraday cage. Our measurements exhibited anomalous effects of unknown origin. In this letter we report new results regarding our investigation into the origins of the observed effects. We report preliminary findings of a correlation analysis between the radioactive decay rates and capacitance time series and space weather related variables (geomagnetic field disturbances and cosmic-ray neutron counts). A significant correlation was observed for specific data sets. The results are presented and possible implications for future work discussed.

Monitoring geomagnetic disturbance predictors using data of ground measurements of cosmic rays

Results from investigating the behavior of zonal components of the first two angular moments of the distribution of cosmic rays observed in 2015 are presented. The global survey approach developed at the Institute of Cosmophysical Research and Aeronomy, Siberian Branch, Russian Academy of Sciences, is used to determine the zonal harmonics. In this technique, the worldwide network of neutron monitors acts as a single multidirectional detector of cosmic rays. It is shown that sharp increases in the positive amplitudes of zonal harmonics, considered to be predictors of geomagnetic field disturbances with a probability of ~0.75, precede geomagnetic storms with Dst < −50 nT. A geomagnetic storm predictor becomes apparent in periods of time from several hours to 1.5 days. Geomagnetic disturbances are currently monitored in real time using the global survey approach based on data from the worldwide neutron monitor database (http://www.nmdb.eu). The initial results from forecasting can be found on the Internet (http://www.ysn.ru/~starodub/SpaceWeather/global_survey_real_time.html).

Solar flares and variation of local geomagnetic field: Measurements by the Huancayo Observatory over 2001-2010

We study the local variation of the geomagnetic field measured by the Huancayo Geomagnetic Observatory, Peru, during 2001-2010. Initially, we sought to relate the SFI values, stored daily in the NOAA's National Geophysical Data Center, with the corresponding geomagnetic index; however, no relation was observed. Nonetheless, subsequently, a comparison between the monthly geomagnetic-activity index and the monthly SFI average allowed observing a temporal correlation between these average indices. This correlation shows that the effect of the solar flares does not simultaneously appear on the corresponding magnetic indices. To investigate this, we selected the most intense X-class flares; then, we checked the magnetic field disturbances observed in the Huancayo Geomagnetic Observatory magnetograms. We found some disturbances of the local geomagnetic field in the second and third day after the corresponding solar flare; however, the disturbance strength of the local geomagnetic field is not correlated with the X-class of the solar flare. Finally, there are some disturbances of the local geomagnetic field that are simultaneous with the X-class solar flares and they show a correlation with the total flux of the solar flare.

Effect of March 9, 2016 Total Solar Eclipse on geomagnetic field variation

During solar eclipse, solar radiation to the Earth is blocked by the Moon. Thus, the ionization process in the ionosphere is disrupted, as well as the variation of geomagnetic field. The disturbance of geomagnetic field is caused by electric current in the E layer of the ionosphere. At low latitude, the current which is dominant in quiet day is the Sq currents. The blocking of solar radiation cause decrement in electron density in the blocked region. The aim of the research is to find the effect of total solar eclipse to the geomagnetic field. The measurement of the geomagnetic field variation during total solar eclipse on March 9, 2016 was carried out at the Meteorological station of BMKG in Ternate (0° 49' 45.20 "N; 127° 22' 54.00" E). By eliminating the geomagnetic disturbance that occurred in a daily geomagnetic field variation, the pattern of quiet day which is usually in a shape of smooth curve became affected. During the total solar eclipse on March 9, 2016 from 00:30 until 02:00 UT, we found that the geomagnetic field variation of the quiet day decreased by -5 nT.

Long-period geomagnetic pulsations as solar flare precursors

We compare long-period pulsations of the horizontal component of the geomagnetic field at intervals that precede extreme solar flares. To this end, we use the wavelet–skeleton technique to process the geomagnetic field disturbances recorded at magnetic stations over a wide geographical range. The synchronization times of wavelet–skeleton spectral distributions of long-period pulsations of geomagnetic oscillations over all magnetic stations are shown as normalized histograms. A few days before an intense solar flare, the histograms show extremes. This means that these extremes can be regarded as flare precursors. The same technique is used to analyze the parameters of near-Earth space. The histograms obtained in this case are free of the aforementioned extrema and, therefore, cannot point to an upcoming flare. The goal of this study is to construct a correlation–spectral method for the short-term prediction of solar flare activity.

A neural network system for estimation of the geomagnetic field disturbance

The paper presents our software system for estimation the degree of disturbance of the geomagnetic field. The system automatically classifies registered geomagnetic data and determines the state of the geomagnetic field for the current day. The results of approbation of the system showed the prospect of its application in problems of estimation and prediction of space weather. The system allows us to allocate weak disturbances of the geomagnetic field, which may occur before strong magnetic storms.

Evolution of the storm magnetic field disturbance around Earth's surface and the associated ring current as deduced from multiple ground observatories

AbstractBased on the continuous magnetic measurements of the multiple ground observatories, the structure of the geomagnetic field disturbance and its temporal variations have been investigated, and the evolution of the storm ring current is deduced accordingly. Assuming that the geomagnetic disturbance around the Earth's surface is approximately linearly varying in space, the spatial gradient of the corrected H (geomagnetic horizontal) component can be obtained from the multiple ground observations. It is found that the maximum difference of the corrected H component around the Earth's surface, as calculated by the gradient of the corrected H component multiplied by the Earth diameter, represents well the asymmetric index Asy‐H. The antidirection of the gradient of the corrected H component can be regarded as pointing to the position of the maximum partial ring current. It is shown that for ordinary magnetic storms with Dst &gt; −200 nT, the maximum partial ring current is located around the duskside during the main phase and the earlier stage of the recovery phase. At the later stage of the recovery phase, the position of the maximum partial ring current can possibly keep rotating eastward, indicating that the energetic electrons may play a significant role and the main ring current carriers may be the electrons at this stage. For the super storms (Dst &lt; −200 nT), the position of the maximum partial ring current is not as regular. Based on physical considerations, this investigation also provides new formulas of the definitions to the symmetric index Sym‐H and asymmetric index Asy‐H.

Geomagnetic field disturbances produced by Sychuan earthquake on April 20th 2013 (Ms=7,0)

Results of observations on location of wave disturbances registered during the preparation and development of the earthquake in the territory of China in Sychuan proovince on April 20th 2013 are analyzed. Experimental data have been obtained at the North Caucasian geophysical observatory, a part of Laboratory of Applied geophysics and volcanology of the IEPh RAS, situated in the area of the Elbrus volcanic center (North Caucasis) [Sobisevich, Gridnev et al., 2008] and the scientific stationary IZMIRAN (Karpogory, subauroral area) as well as magnetic observatories «Odessa» and «Kiev» in the territory of Ukraine. In the structure of observed abnormal magnetic disturbances in variations of the earth’s magnetic field, precursors of the earthquake, specific magnetic pseudo-wave forms of ULF range have been distinguished and partly analyzed, which reflect the processes of preparation and development of the crustal earthquake under examination. Materials on mac-roseismic and seismologic manifestations of the processes of preparation of the earthquake source as well as brief information on its tectonic location have been presented.

Geomagnetic field effects of the Chelyabinsk meteoroid

An analysis was conducted of time variations in geomagnetic field components on the day of the Chelyabinsk meteorite event (February 15, 2013) and on control days (February 12 and 16, 2013). The analysis uses the data collected by magnetic observatories in Novosibirsk, Almaty, Kyiv, and Lviv. The distance R from the explosion site to the observatories varies in the range 1200–2700 km. The flyby and explosion of the Chelyabinsk cosmic body is found to have been accompanied by variations mainly in the horizontal component of the geomagnetic field. The variations are quasi-periodic with a period of 30–40 min, an amplitude of 0.5–2 nT for R ≈ 2700−1200 km, respectively, and a duration of 2–3 h. The horizontal velocity of the geomagnetic field disturbances is close to 260–370 m/s. A theoretical model of wave disturbances is proposed. According to the model, wave disturbances in the geomagnetic field are caused (a) by the motion of the gravity wave generated in the atmosphere by the falling space body and (b) by traveling ionospheric disturbances, which modulate the ionospheric current at dynamo altitudes. The calculated amplitudes of the wave disturbances are 0.6–1.8 nT for R ≈ 2700−1200 km, respectively. The estimates are in good agreement with the observational data. Disturbances in the geomagnetic field level (geomagnetic pulsations) in the period range 1–1000 s are negligible (less than 1 nT).

Stronger geomagnetic fields may be a risk factor of male suicides

Some previous studies have shown a positive relation between geomagnetic disturbances and an increased incidence of suicide. If such a relation exists, stronger geomagnetic fields may affect the number of suicides, because stronger geomagnetic fields generally cause larger geomagnetic field disturbances. Therefore, we here investigated the relation between local geomagnetic field magnetic flux density and the standardized morbidity ratios (SMR) for suicide by each prefecture in Japan. Monthly suicide data for each prefecture in the period January 1999 to December 2008 was obtained, and it was found that a total of 216 171 male individuals and 85 154 female individuals committed suicide during this period. A multiple linear regression analysis was carried out with a backward elimination procedure. The SMR for suicide by each prefecture was taken as the response variable and the explanatory variables were each prefecture's local geomagnetic field magnetic flux density (nT), north latitude (°), monthly mean unemployment rate (%), monthly mean air pressure (hPa), monthly mean air temperature (°C), monthly mean humidity (%), and monthly total day length (hours). Analyses were carried out separately for each sex. In the multiple linear regression analysis for male subjects, the local geomagnetic field magnetic flux density (nT), monthly mean unemployment rate (%), and monthly mean humidity (%) were associated with the incidence of suicide, but in the multiple linear regression analysis of female subjects, only north latitude was associated with that. In this study, we generated a hypothesis that stronger geomagnetic fields affect the number of cases of male suicide.

On extreme geomagnetic storms

Extreme geomagnetic storms are considered as one of the major natural hazards for technology-dependent society. Geomagnetic field disturbances can disrupt the operation of critical infrastructures relying on space-based assets, and can also result in terrestrial effects, such as the Quebec electrical disruption in 1989. Forecasting potential hazards is a matter of high priority, but considering large flares as the only criterion for early-warning systems has demonstrated to release a large amount of false alarms and misses. Moreover, the quantification of the severity of the geomagnetic disturbance at the terrestrial surface using indices as Dst cannot be considered as the best approach to give account of the damage in utilities. High temporal resolution local indices come out as a possible solution to this issue, as disturbances recorded at the terrestrial surface differ largely both in latitude and longitude. The recovery phase of extreme storms presents also some peculiar features which make it different from other less intense storms. This paper goes through all these issues related to extreme storms by analysing a few events, highlighting the March 1989 storm, related to the Quebec blackout, and the October 2003 event, when several transformers burnt out in South Africa.

Global distributions of storm-time ionospheric currents as seen in geomagnetic field variations

To investigate temporal and spatial evolution of global geomagnetic field variations from high-latitude to the equator during geomagnetic storms, we analyzed ground geomagnetic field disturbances from high latitudes to the magnetic equator. The daytime ionospheric equivalent current during the storm main phase showed that twin-vortex ionospheric currents driven by the Region 1 field-aligned currents (R1 FACs) are intensified significantly and expand to the low-latitude region of ~30° magnetic latitude. Centers of the currents were located around 70° and 65° in the morning and afternoon, respectively. Corresponding to intensification of the R1 FACs, an enhancement of the eastward/westward equatorial electrojet occurred at the daytime/nighttime dip equator. This signature suggests that the enhanced convection electric field penetrates to both the daytime and nighttime equator. During the recovery phase, the daytime equivalent current showed that two new pairs of twin vortices, which are different from two-cell ionospheric currents driven by the R1 FACs, appear in the polar cap and mid latitude. The former led to enhanced northward B z (NBZ) FACs driven by lobe reconnection tailward of the cusps, owing to the northward interplanetary magnetic field (IMF). The latter was generated by enhanced Region 2 field-aligned currents (R2 FACs). Associated with these magnetic field variations in the mid-latitudes and polar cap, the equatorial magnetic field variation showed a strongly negative signature, produced by the westward equatorial electrojet current caused by the dusk-to-dawn electric field.

Interaction between plasma structures in an unstable ionospheric plasma

A vortex structure renders additional stability to plasma irregularities stretched along magnetic field lines. Plasma irregularities extended over several tens of kilometers are registered with rocket and satellite equipment in the topside ionosphere. The registered scale of irregularities depends on the spatial and time resolution of the equipment used. Irregular structures were registered in the ionosphere during experiments with barium clouds and jets, when a plasma irregularity separated into strata extended over several meters and several kilometers across the geomagnetic field. It has been indicated that plasma vortices can be generated in an unstable plasma in a situation when its quasi-neutrality is disturbed. Local geomagnetic field disturbances will be caused by the appearance of a proper vortex magnetic field. Plasma vortices can interact in an inhomogeneous plasma with an unstable electron component. Such interactions are related to the transformation of the phase volume of free electrostatic oscillations in the frequency-wave vector space.

Days of “Zero” level geomagnetic activity accompanied by the high neutron activity and dynamics of some medical events—Antipodes to geomagnetic storms

The links of many medical-biological events with high levels of geomagnetic activity (GMA) are widely discussed. In recent years, several medical phenomena were described in inverse distribution by time with GMA. Also a concurrent to GMA and solar activity force-cosmic ray activity (CRA) and closely related high energy neutron and proton fluxes are studied as a forces dominating at low GMA and solar activity in relation to considered medical events. The aim of this study was to explore the distribution of some important medical events on days with “Zero” GMA levels, accompanied by high CRA (neutron activity). Medical event data of the Grand Baku region (more than 3 mln inhabitants), Azerbaijan, with daily distribution on the time 1 Dec. 2002-31 Dec. 2007 was compared to daily GMA Kp indices in general (Kp > 0, 1837 days) and 34 days daily GMA indices Kp = 0. Daily CRA data was also compared using neutron monitoring data from two stations. Daily averaged data and their standard deviations on the mentioned GMA levels were compared and statistical significance was established. Results revealed a significant rise in the number of emergencies (n = 1,567,576) and total deaths number (n = 46,360) at the days of “Zero” GMA level. These days were accompanied by significant rise of CRA (neutron activity). For Sudden Cardiac Deaths (SCD, n = 1615) and cerebral stroke (CVA, n =10,054) the increase achieved strong trend to significance level. Acute Myocardial Infarction occurrence (morbidity) and trauma were also absolutely more registered at days with “Zero” GMA level, despite the small number of such days. The average Infection numbers show an inverse relationship with absolutely high registry at the “Zero” GMA level days. Study linking environmental physical activity levels and the human medical data shows that geomagnetic field variations accompanied by the increased level of cosmic ray activity, can have either direct or indirect adverse effects on human health and physiology, even when the magnitude of the geomagnetic field disturbance is extremely small or even is equal to zero. On days of “Zero” daily Kp indices describing Geomagnetic Activity, accompanied by high Cosmic Ray Activity (neutron activity), more medical emergencies and total death number (daily) occurred. Sudden Cardiac Deaths and Cerebral Stroke numbers show a strong trend to significant rise. Absolute increase of number of Acute Myocardial Infarction and less Infections, not achieving statistical significance, was also observed. These results are additional data for considering Cosmic Ray Activity (neutron activity) as an additional factor involved in time distribution of human medical events.

The association between solar particle events, geomagnetic storms, and hospital admissions for myocardial infarction

Eruptive activity of the Sun produces intensive fluxes of energetic particles and disturbances in geomagnetic field. It has been found that solar and geomagnetic activities affect the cardiovascular system. In this study, we investigated whether solar particle events (SPE) and geomagnetic storms (GS) affect risk of emergency hospitalization for first-time myocardial infarction (MI). The effect of environmental variables is analyzed separately for MI with and without elevation of ST segment in electrocardiogram. A case-crossover study design was used to analyze MI in 2,008 hospitalized patients at the Hospital of Kaunas University of Medicine, Lithuania, from January 1, 2004 to December 31, 2005. We evaluated the associations between SPE, GS, and daily number of emergency hospital admission for MI by Poisson regression, controlling for seasonal variation, weekdays, and meteorological factors. During days of SPE in conjunction with GS, the risk of hospital admissions for MI with ST elevation increased by 39 % (RR = 1.39; 95 % CI 1.02–1.91). Two days after SPE that going till GS, the risk of admission for MI without ST elevation increased by 54 % (RR = 1.54; 95 % CI 1.05–2.24). The major GS without increased proton flux with particle energies >10 MeV does not increase the risk of admission for MI without ST elevation. Only GS occurred after SPE increased the risk of admission for MI without ST elevation. These findings suggest that SPE going till GS or SPE in conjunction with GS affect on cardiovascular system. The environmental factors have different effects on the risk of myocardial infarction with and without ST elevation.

Space weather hazards and their impact on human cardio-health state parameters on Earth

Recent multi-disciplinary heliobiological and biometeorological researches reveal that the human organism is sensitive to environmental physical activity changes and reacts to them through variations of the physiological parameters of the human body. In this study, electrocardiograms of functionally healthy persons, who were digitally registered at the Laboratory of Heliobiology located in the Medical Centre INAM (Baku, Azerbaijan), were studied in relation to different levels of cosmic ray activity and geomagnetic field disturbances. In total, 1,673 daily digital data of heart rate values and time series of beat-to-beat heart rate intervals (RR intervals) were registered for the time period July 15, 2006–March 31, 2008, which includes the period of December 2006, when intense cosmic ray events and strong geomagnetic disturbances occurred. The statistical significance of the influence of geomagnetic activity levels and cosmic ray intensity variations on heart rate and RR intervals was estimated. Results revealed that heart rate increase and RR intervals variations were more pronounced for high levels of geomagnetic activity and large cosmic ray intensity decreases, whereas very small or even minimum cosmic ray intensity variations did not affect heart rate dynamics. Moreover, heart rate increased on the days before, during and after geomagnetic storms with high intensities and on the days preceding, and following cosmic ray intensity decreases.

Possible Ionospheric Electromagnetic Perturbations Induced by the Ms7.1 Yushu Earthquake

The power spectrum density (PSD) of magnetic field in the ELF/VLF band recorded by the experiment IMSC onboard the DEMETER satellite were used to study the Ms7.1 Yushu earthquake taking place on April 13, 2010 in China. The results indicate that possible ionospheric electromagnetic perturbations occurring 4 days before the earthquake in the frequency range [370–897 Hz]. Along the orbit 30880_up, which passed over the epicenter area on 9 April, enhanced PSD value of magnetic field at 410 Hz was detected both over the epicentral area and its conjugate point in the southern hemisphere. While on revisited orbits during other days (before and after the earthquake) the magnetic field spectra remained at a relatively low level. In order to be sure that the electromagnetic disturbances were induced by this Yushu earthquake, relative variations of the magnetic field in the ELF/VLF range [370–897 Hz] were calculated and compared with the normal background during 3 years (2007, 2008 and 2009) in the time interval from Jan. 1st to Apr. 30 and in the area [23°N–43°N, 86°E–106°E]. The results show that the normal level of magnetic field in this area is relatively low (~10−7 nT2/Hz), but a large increase occurred from Apr. 1st to Apr. 14 which exceeds 5σb. After the earthquake, the magnetic field in the ELF/VLF range gradually decreased. In order to exclude the influence of geomagnetic field activity, we selected only the data recorded during magnetically quiet local night-times. In addition, artificial noises were also removed from the dataset used in the present paper. Therefore the observed perturbations were independent of geomagnetic field disturbances, and might be attributed to seismic activity.