Influence Of Geomagnetic Activity Research Articles

Impact of different solar extreme ultraviolet (EUV) proxies and Ap index on hmF2 trend analysis

Abstract. Long-term trend estimation in the peak height of the F2 layer, hmF2, needs the previous filtering of much stronger natural variations such as those linked to the diurnal, seasonal, and solar activity cycles. If not filtered, they need to be included in the model used to estimate the trend. The same happens with the maximum ionospheric electron density that occurs in this layer, NmF2, which is usually analyzed through the F2 layer critical frequency, foF2. While diurnal and seasonal variations can be easily managed, filtering the effects of solar activity presents more challenges, as does the influence of geomagnetic activity. However, recent decades have shown that geomagnetic activity may not significantly impact trend assessments. On the other hand, the choice of solar activity proxies for filtering has been shown to influence trend values in foF2, potentially altering even the trend's sign. This study examines the impact of different solar activity proxies on hmF2 trend estimations using data updated to 2022, including the ascending phase of solar cycle 25, and explores the effect of including the Ap index as a filtering factor. The results obtained based on two mid-latitude stations are also comparatively analyzed to those obtained for foF2. The main findings indicate that the squared correlation coefficient, r2, between hmF2 and solar proxies, regardless of the model used or the inclusion of the Ap index, is consistently lower than in the corresponding foF2 cases. This lower r2 value in hmF2 suggests a greater amount of unexplained variance, indicating that there is significant room for improvement in these models. However, in terms of trend values, foF2 shows greater variability depending on the proxy used, whereas the inclusion or exclusion of the Ap index does not significantly affect these trends. This suggests that foF2 trends are more sensitive to the choice of solar activity proxy. In contrast, hmF2 trends, while generally negative, exhibit greater stability than foF2 trends.

Seasonal dynamics of cardiovascular events in the Russian Federation

Aim. To study the seasonal dynamics of cardiovascular events (CVE) in the Russian Federation (RF) using medical and statistical data for the period 2016-2019, and also to establish an association of CVE risk with meteorological conditions.Material and methods. We used data on hospitalizations for 2016-2019 for hemorrhagic stroke (HS), ischemic stroke (IS), myocardial infarction (MI), and acute coronary syndrome (ACS).Results. Data analysis showed that the maximum number of HSs occurred in winter and spring, and the minimum in summer. The maximum number of ISs was recorded in spring and summer, while the minimum in winter and autumn. ACS occurred more often in winter and spring, MI — more often in spring. ACS was accompanied by MI in 44% of cases. In winter, the probability of HS increased with decreasing latitude.In summer, the risk of HS and IS was greater at lower air temperatures. In summer, the probability of IS and MI was associated with lower values of atmospheric pressure and partial density of oxygen (ρO2). In winter, the risk of IS increased at highr atmospheric pressure values. No convincing evidence was obtained of the influence of geomagnetic activity on the seasonal dynamics of the CVEs either throughout the Russian Federation or in the circumpolar regions.Conclusion. As a result, meteorological conditions influence the seasonal risk of CVEs. A decrease in ρO2 in summer significantly increases the CVE risk associated with ischemia, which should be taken into account when preventing CVEs.

Small‐Scale Field‐Aligned Currents of Intense Amplitude Resolved by the Swarm Satellites

AbstractIn this study we used the Level‐2 product of field‐aligned currents (FACs) from the Swarm satellites, to check the distribution characteristics of small‐scale FACs (SSFACs) of intense amplitude. Data applied covers 9 years from December 2013 to April 2023. Based on the statistical analysis on the amplitude, the SSFACs in this study is defined with amplitude larger than 20 μA/m2, which is also by two orders larger than the well‐known large‐scale R1 and R2 FACs (about 0.2 μA/m2). Such an intense amplitude indicates that it should play an important role in the magnetosphere‐ionosphere coupling. The location of the SSFACs observed is general between 60°∼80° and −80°∼−60° magnetic latitude, which is coincidently inside the auroral oval. The occurrence of the SSFACs depends on both solar activity and geomagnetic activity, and the influence of geomagnetic activity is more important than that of solar activity. By further checking the simultaneous in situ plasma density measured by Swarm, we find that the SSFACs are always associated with clear plasma density fluctuations. This suggests that the SSFACs play an important role for causing the small‐scale plasma density irregularities at auroral latitude.

Influence of geomagnetic activity on the southern atmosphere and its cross‐seasonal association with SAM

AbstractThis study investigates the interannual cross‐seasonal association between the winter energetic particle precipitation, which is related to the geomagnetic activity (GA), and the southern annular mode (SAM) in the following summer by employing the ERA5 reanalysis dataset. The results reveal a marked negative correlation between these variables on an interannual timescale. Therefore, we analyse the GA signatures in the southern atmosphere and find that the evolution of SAM to the negative phase driven by GA may be caused by the following two mechanisms: First, for high GA levels, the middle and lower stratospheric polar vortex becomes weaker from October to November, with considerable changes in the stratospheric thermal structure and more anomalous planetary wave upwelling, accompanied by weakening of the circumpolar westerly. Over time, the anomalous signal from the upper layer can be transmitted downward and is conducive to inducing and strengthening the negative SAM in the following summer, which may serve as the stratospheric pathway for the geomagnetic impact on the SAM and Southern Hemisphere (SH) climate. Second, another possible way is that the preceding GA also appreciably regulates negative anomalies in the Ferrel circulation in SH, implying poleward anomalies in the direction of the pressure gradient, which promotes the development and enhancement of the negative phase of the SAM. In addition, easterly quasi‐biennial oscillation conditioning plays a positive role in the response of the southern atmosphere to geomagnetic forcing, thereby strengthening the connection between them.

Исследование влияния геомагнитной активности на функционирование систем железнодорожной автоматики в Арктической зоне России

The authors study the possible influence of geomagnetic activity of railway automatics in the Russian Arctic. For the analysis they use the indices of global and regional geomagnetic activity along with the archive of failures on the Northern section of the Oktyabrskaya railway in 2001—2006. The geomagnetic activity is found to be higher for days with failures than for days without the ones. This effect manifests itself in different types of geomagnetic disturbances, including magnetic storms, characterized by the storm index Dst, auroral activations, quantified in AE and EI indices, as well as in local index WY indicating spectral power of geomagnetic variations in milliHerz frequency range. The maximum differences for days with and without failures are obtained for index values averaged over 2—4 days. At the same time, the researchers have found no significant differences between failures for which a cause not related to geomagnetic disturbance is a priori indicated, and those for which such a cause is not identified.

Rainfall and Temperature Variations over Burkina Faso: Possible Influence of Geomagnetic Activity, Solar Activity and Associated Energies from 1975 to 2020

This study investigates climatic parameters (rainfall, and temperature) over Burkina Faso and the possible role of solar activity and its induced energies. Through morphological investigations, we analyzed solar activity indices (sunspot number, IMF, PC index, Cosmic rays) over the last three solar cycles (1975-2020). Results about interplanetary heating show that joule heating is well correlated with the dynamic pressure of the solar plasma. Climate parameters (rainfall, Temperature) variabilities are modulated by disturbances in solar activity: 1) quiet solar characterized by a drop in solar plasma’s parameters is associated with important cloud cover and consequently bring important rainfall which chills terrestrial atmosphere, 2) active solar characterized by important input energy is associated with weak incident cosmic ray consequently with low cloudiness which brings warming. Thus, the possible natural link can be suggested between solar activity and climatic parameters even if it is not the only factor of global warming.

Assessment of the Earth’s Cold Plasmatrough Modeling by Using Van Allen Probes/EMFISIS and Arase/PWE Electron Density Data

AbstractThe Space Weather Integrated Forecasting Framework (SWIFF) Plasmasphere Model (SPM) is a 3D kinetic model of the plasmasphere coupled to the ionosphere. This combined system has been routinely used to evaluate principally the plasmapause formation and evolution, and the plasmasphere’s dynamics. The model contains analytical equations for the plasmasphere and plasmatrough regions that have been empirically determined using observations of satellite and ground‐based data. In the present work, a revision of the plasmatrough equations is proposed using electron density data from the Van Allen Probes mission and paying particular attention to the spatiotemporal variation as well as to geomagnetic activity influence. Comparisons are performed with other parametrizations and with electron density data from the Arase mission. This assessment demonstrates that the plasmatrough electron density was slightly underestimated with respect to the new observations, in particular for high L values (L > 3) and high geomagnetic activity. In addition, the overall performance of the new parametrization follows a satisfactory general trend despite a large variability of density data observed in the plasmatrough. The plasmatrough is separated from the refilling zone in the model by considering vestigial and outer edge plasmapause positions.

A New Model for Ionospheric Total Electron Content: The Impact of Solar Flux Proxies and Indices

AbstractWe present a new high‐resolution empirical model for the ionospheric total electron content (TEC). TEC data are obtained from the global navigation satellite system (GNSS) receivers with a 1° × 1° spatial resolution and 5‐min temporal resolution. The linear regression model is developed at 45°N, 0°E for the years 2000–2019 with 30‐min temporal resolution, unprecedented for typical empirical ionospheric models. The model describes dependency of TEC on solar flux, season, geomagnetic activity, and local time. Parameters describing solar and geomagnetic activity are evaluated. In particular, several options for solar flux input to the model are compared, including the 10.7 cm solar radio flux (F10.7), the Mg II core‐to‐wing ratio, and formulations of the solar extreme ultraviolet flux (EUV). Ultimately, the extreme ultraviolet flux presented by the Flare Irradiance Spectral Model, integrated from 0.05 to 105.05 nm, best represents the solar flux input to the model. TEC time delays to this solar parameter on the order of several days as well as seasonal modulation of the solar flux terms are included. The Ap3 index and its history are used to reflect the influence of geomagnetic activity. The root mean squared error of the model (relative to the mean TEC observed in the 30‐min window) is 1.9539 TECu. A validation of this model for the first 3 months of 2020 shows excellent agreement with data. The new model shows significant improvement over the International Reference Ionosphere 2016 (IRI‐2016) when the two are compared during 2008 and 2012.

Экзогенные факторы фрагментации ядерной ДНК сперматозоидов быков‑производителей

Herd reproduction is the most important indicator of the economic efficiency of the industry. Assisted reproductive technology, especially artificial insemination, is widely used in dairy farming. When using this method, tens of thousands of cows and heifers are inseminated with the seed of a single bull, therefore, the used biomaterial must meet high requirements, since the use of low-quality sperm products can lead to multi-million losses. The reproductive performance of breeding bulls depends on numerous biotic and abiotic factors. breeding bulls depends on numerous biotic and abiotic factors. The purpose of the study the influence of meteorological factors on the biological usefulness of sperm from bulls of different breeds. A multidimensional dispersion analysis of the effect of temperature and geomagnetic activity on the quality of spermatozoa was performed. The results of multidimensional dispersion analysis show that the combination of temperature factors with geomagnetic activity has a statistically significant effect on the content of spermatozoa with abnormal movement in the fresh seed and on the activity of spermatozoa (p<0,05). Geomagnetic activity (K-index ≥5,0) leads to an increase in the proportion of spermatozoa with pathological morphology. This trend was observed regardless of the season of the year. During the summer period, on days with increased geomagnetic activity, the content of spermatozoa with pathology increased by 66% compared to the period when there is no magnetic disturbance. Under the influence of geomagnetic activity, the proportion of spermatozoa with abnormal movement increased – such spermatozoa in the ejaculate contained an average of 10,2%, depending on the season and temperature, this indicator varied from 6 to 21,5%. High geomagnetic activity and temperature lead to an increase in the proportion of spermatozoa with a violation of the structure of nDNA.

ON THE CHARACTER OF AN ARTIFICIAL SATELLITE DRAG UNDER VARIOUS STATES OF SOLAR AND GEOMAGNETIC ACTIVITY

Purpose: The artificial satellites drag in the atmosphere remains an urgent problem to date. In this work, the artificial satellites data are used in order to study the atmosphere state under various manifestations of solar and geomagnetic activity. The selected satelites were moving uncontrollable being good indicators of the upper atmosphere state. The B-star (drag term) drag coefficient is used in this work. This term is used in the SGP and SDP models to take into account the resistance of the atmosphere to the satelite orbital motion. The data of the drag of two artificial satellites, one moving in elliptical and the other in circular orbits at midlatitudes (orbital plane angles of 58°-60°) were considered. These data include the end of the 23rd solar activity cycle, as well as the growth, the maximum and the decay phases of the 24th solar cycle (years 2005–2017). Seven periods of anomalous drag of the satellites were analyzed. They are: 4 monthly periods (two in 2005 and two in 2011) and 3 yearly periods (within 19.07.2014 to 22.08.2015), five-year long (2005–2010) and six-year long (2011–2017) periods. Design/methodology/approach: The periodogram analysis was made. This allowed to reveal the periodic processes in changes in the state of the atmosphere of different duration. The correlation coefficients of the B-star drag term with the indices of solar and geomagnetic activity were calculated. The analysis of extreme drag of the satellites in the periods of the increased solar and geomagnetic activity (intervals of observation lasting a month) was made. Findings: Using the solar and geomagnetic data we found that some month-long part of the anomalous drag periods were followed by flares on the Sun and the arrival of the coronal mass ejections into the near-Earth space. At time intervals of yearlong observations the highest values (0.5-0.7) were obtained for the coefficients of the B-star parameter correlation with the solar activity indices – solar radiation at the wavelength of 10.7 cm, F10.7, and Lyman alpha radiation, Lα. At monthly time intervals, the largest values of the correlation coefficients were obtained for the B-stars with the electron fluxes with energies above 0.6 and 2 MeV, E, (0.3-0.5), the Lyman alpha radiation, Lα, (0.58–0.73 for a сircular orbit satellite), and the solar constant, TSI, (0.3–0.6), as well as the geomagnetic storms intensity index, Dst , (0.66–0.69). Periodogram calculations show the presence of a whole spectrum of periods in the deceleration of a circular orbit satellite and a dedicated period for an elliptical orbit satellite. Conclusions: The B-star drag term dependences on the indices of solar and geomagnetic activity during some periods of their intensification for the 23–24 cycles of solar activity are considered. The periodogram analysis made together with the analysis of the conditions and parameters of space weather allows to see the general and more detailed picture of the solar and geomagnetic activity influence on the change in the motion of the satellite in the atmosphere. The B-star drag term helps to consider only the atmosphere influence on the artificial satellite movement in the near-Earth space. Key words: artificial satellite, atmosphere, artificial satellite drag, solar activity, geomagnetic activity, space weather

Influence of Geomagnetic Activity on Derivation of Temperatures From Meteor Wind Radars

AbstractEchoes from meteor trails can be analyzed to derive diffusion coefficient and thereafter estimates of neutral temperatures, typically around 90 km altitude. The method entails some assumptions and, usually, use of model pressures. Even so, variations in derived temperatures have been assumed to be representative and indicators of other mesospheric processes. However, we now find that the observed variations, seen as enhancements, are very closely associated with enhancements in geomagnetic activity. Here we introduce a metric for describing geomagnetic activity (as an alternative to, e.g., the k‐index) and suggest a methodology for near‐real‐time correction of results.

Influence of the Ionosphere on the Parameters of the GPS Navigation Signals during a Geomagnetic Substorm

The influence of geomagnetic activity on slips of navigation signals of the global positioning system (GPS), as well as an increase in the amplitude of jumps in the total electron content at high latitudes, has been studied in detail. It is shown that the navigation signal of the L2 frequency is subject to more frequent malfunctions than the L1 frequencies, both in calm conditions and during geomagnetic disturbances. The probability of total electron content jumps is higher than the probability of phase slips at the L1 and L2 frequencies. The maximum disruptions and the frequency of large jumps in the total electron content are observed during the recovery phase of the geomagnetic substorm. The data from the whole-sky camera, magnetometers, and the interplanetary magnetic field used in this study make it possible to monitor the time evolution of a substorm and to study it in detail. The indicated features of the signal behavior are apparently caused by the precipitation of auroral particles, which usually occur during geomagnetic substorms in high latitude regions.

A note on the statistical evidence for an influence of geomagnetic activity on Northern Hemisphere seasonal-mean stratospheric temperatures using the Japanese 55-year Reanalysis

Abstract. We employ JRA-55 (Japanese 55-year Reanalysis), a recent second-generation global reanalysis providing data of high quality in the stratosphere, to examine whether a distinguishable effect of geomagnetic activity on Northern Hemisphere stratospheric temperatures can be detected. We focus on how the statistical significance of stratospheric temperature differences may be robustly assessed during years with high and low geomagnetic activity. Two problems must be overcome. The first is the temporal autocorrelation of the data, which is addressed with a correction of the t statistics by means of the estimate of the number of independent values in the series of correlated values. The second is the problem of multiplicity due to strong spatial autocorrelations, which is addressed by means of a false discovery rate (FDR) procedure. We find that the statistical tests fail to formally reject the null hypothesis, i.e. no significant response to geomagnetic activity can be found in the seasonal-mean Northern Hemisphere stratospheric temperature record.

Effect of Ap-Index of Geomagnetic Activity on S&P 500 Stock Market Return

Geomagnetic activity with global influence is an essential object of space weather research and is a significant link in the section of the solar wind-magnetospheric coupling process. Research so far provides strong evidence that geomagnetic activity affects stock investment decisions by influencing human health, mood, and human behaviours. Therefore, this research investigates the empirical association between geomagnetic activity and stock market return. Overall, we find that geomagnetic activity exerts a negative influence on the return of the US stock market. Further, market liquidity effectively magnifies the effect of geomagnetic activity. Inconsistent with previous literature, this effect is not mainly caused by the semiannual variation of geomagnetic activity. Our research contributes to the introduction of geomagnetic indices to financial economics studies on the impact of geomagnetic activity influence on stock market return.

МНОЖЕСТВЕННЫЕ КОРРЕЛЯЦИОННЫЕ МОДЕЛИ ЗАВИСИМОСТИ ПОТОКОВ ИЗЛУЧЕНИЯ КОСМИЧЕСКИХ РАДИОИСТОЧНИКОВ В ДЕКАМЕТРОВОМ ДИАПАЗОНЕ ОТ ЭКСТРЕМАЛЬНЫХ ПРОЯВЛЕНИЙ КОСМИЧЕСКОЙ ПОГОДЫ

PACS numbers: 95.55.Jz, 95.85.Bh, 96.50.Wx Purpose: Investigation of the effects of the influence of solar and geomagnetic activity on the condition of the Earth’s upper atmosphere by the method of “transmission through” it with the radiation of cosmic radio sources. Design/methodology/approach: Monitoring of the fluxes of powerful galactic and extragalactic radio sources is carried out at the URAN-4 radio telescope of the Odesa Observatory of the Institute of Radio Astronomy of the NAS of Ukraine since 1987 till now. The monitoring program includes radio galaxies 3C274, 3C405 and supernova remnants 3C144, 3C461. Changes of fluxes of radiation sources at decameter waves are determined by the condition of an ionosphere resulted due to space weather variation. Findings: The models of multiple correlation dependence of fluxes of radio sources on the factors forming space weather for the periods of extreme conditions of the solar and geomagnetic activity are considered. The explanatory variables are divided into three groups: indices of solar activity, flows of particles, magnetic field components. Over 60 models of the multiple correlation dependence were calculated. Values of a multiple coefficient of correlation within 0.86 to 0.99 were obtained. The greatest contribution to the quantity of a multiple coefficient of correlation give: solar radio emission at the wave of 10.7 cm (F10.7), the total area of groups of spots (Sp), flows of electrons (E) and protons (P). Conclusions: Monitoring of fluxes of space radio sources made at the “URAN-4” radio telescope makes it possible to “transmit through” the Earth ionosphere above the radio telescope and determines the integral effect of the solar and geomagnetic activity influence on it. The great amount of the data observed with using the “URAN-4” radio telescope allows more detailed study of the influence of space weather effects in the ionosphere to be made in our next works. Key words: upper atmosphere, solar activity, geomagnetic activity, space weather Manuscript submitted 26.06.2018 Radio phys. radio astron. 2018, 23(3): 189-202 REFERENCES 1. RYABOV, M. I., PANISHKO, S. K. and GUGLYA, L. I., 2011. Space weather impacts on the Earth’s upper atmosphere according to the monitoring of powerful radio sources fluxes at the URAN-4 radio telescope (Institute of Radio Astronomy, NAS of Ukraine). Odessa Astronomical Publications . vol. 24, pp. 159–161. (in Russian). 2. SOBITNIAK, L. I., RYABOV, M. I., SUKHAREV, A. L. and PANISHKO, S. K., 2017. Structure of variability indexes of cosmic weather as applied to data monitoring of fluxes of radio sources at the “URAN-4” radio telescope. Radio Phys. Radio Astron . vol. 22, no. 4, pp. 294–303 (in Russian). DOI: https://doi.org/10.15407/rpra22.04.294 3. BOROVIKOV, V. A., 2001. STATISTICA: The art of data analysis on a computer . St. Petersburg: Piter Publ. (in Russian). 4. BRUZEK, A. and DURRANT, C. J., eds., 1977. Illustrated glossary for solar and solar-terrestrial physics . Dordrecht, Boston: D. Reidel Pub. Co. DOI: https://doi.org/10.1007/978-94-010-1245-4 5. IVANOV-KHOLODNYI, G. S. and NIKOLSKY, G. M., 1969. The Sun and Ionosphere. Short wave solar radiation and its effect on the ionosphere . Moscow, Russia: Nauka Publ. (in Russian). 6. RUSSELL, C. T. and MCPHERRON, R. L., 1973. Semiannual Variation of Geomagnetic Activity. J. Geophys. Res. Space Phys . vol. 78, is. 1, pp. 92–108. DOI: https://doi.org/10.1029/JA078i001p00092 7. ZELENYI, L. M. and VESELOVSKIY, I. S., eds., 2008. Plasma heliogeophysics . Moscow, Russia: Fizmatlit Publ. vol. 1-2. (in Russian). 8. MIROSHNICHENKO, L. I., 2011. Physics of the Sun and solar-terrestrial connections . Moscow, Russia: Universitetskaya Kniga Publ. (in Russian). 9. OBRIDKO, V. N. and NAGOVITSYN, YU. A., 2017. Solar activity, cyclicity and prediction methods . St. Petersburg: VVM Publ. (in Russian).

Influence of geomagnetic activity on mesopause temperature over Yakutia

Abstract. The long-term temperature changes of the mesopause region at the hydroxyl molecule OH (6-2) nighttime height and its connection with the geomagnetic activity during the 23rd and beginning of the 24th solar cycles are presented. Measurements were conducted with an infrared digital spectrograph at the Maimaga station (63∘ N, 129.5∘ E). The hydroxyl rotational temperature (TOH) is assumed to be equal to the neutral atmosphere temperature at the altitude of ∼ 87 km. The average temperatures obtained for the period 1999 to 2015 are considered. The season of observations starts at the beginning of August and lasts until the middle of May. The maximum of the seasonally averaged temperatures is delayed by 2 years relative to the maximum of the solar radio emission flux (wavelength of 10.7 cm), and correlates with a change in geomagnetic activity (Ap index). Temperature grouping in accordance with the geomagnetic activity level showed that in years with high activity (Ap > 8), the mesopause temperature from October to February is about 10 K higher than in years with low activity (Ap < = 8). Cross-correlation analysis showed no temporal shift between geomagnetic activity and temperature. The correlation coefficient is equal to 0.51 at the 95 % level.

The Effects of Space and Terrestrial Weather Factors on Arterial Stiffness and Endothelial Function in Humans

A differential evolution algorithm was used to detect the biotropic influence of geomagnetic activity on several parameters of human vascular tone. Studies of the characteristics of vascular tone in healthy volunteers showed that arterial stiffness and endothelial function, as well as blood pressure and heart rate, depend on the geomagnetic and, in most cases, weather conditions. The pulse wave velocity (PWV) was measured to characterize the arterial stiffness and was found to be the most sensitive to the effects of space weather parameters. The strength of the effect of geomagnetic activity was for the first time observed to depend on the configuration of terrestrial weather parameters. A linear correlation between the K index of geomagnetic activity and PWV was estimated at r =–0.44 (p = 0.0003), although the relationship was detectable exclusively in the case of certain terrestrial weather parameters. Endothelial dysfunction and the pulse-rate response to variations in geomagnetic activity implicated nitrogen monoxide in body adaptation to variations in geomagnetic activity.

Evaluation of the Influence of Geomagnetic Activity on Metrological Characteristics of Inclinometric Information Measuring Systems

The influence of geomagnetic activity on the metrological characteristics of inclinometric informationmeasuring systems was studied. The necessity of introducing indices of geomagnetic activity with the aim of formalizing this influence and clarifying the metrological characteristics of inclinometer equipment is substantiated. A step-by-step methodology for calculating the introduced indices is proposed and described. We numerically calculate and estimate the proposed indexes on the basis of real models of geomagnetic activity over a 72-hour time period. The obtained results are analyzed.

Influence of geomagnetic activity and atmospheric pressure in hypertensive adults.

We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

Induction effects of geomagnetic disturbances in the geo-electric field variations at low latitudes

Abstract. In this study we examined the influences of geomagnetic activity on the Earth surface electric field variations at low latitudes. During the International Equatorial Electrojet Year (IEEY) various experiments were performed along 5° W in West Africa from 1992 to 1995. Among other instruments, 10 stations equipped with magnetometers and telluric electric field lines operated along a meridian chain across the geomagnetic dip equator from November 1992 to December 1994. In the present work, the induced effects of space-weather-related geomagnetic disturbances in the equatorial electrojet (EEJ) influence area in West Africa were examined. For that purpose, variations in the north–south (Ex) and east–west (Ey) components of telluric electric field were analyzed, along with that of the three components (H, D and Z) of the geomagnetic field during the geomagnetic storm of 17 February 1993 and the solar flare observed on 4 April 1993. The most important induction effects during these events are associated with brisk impulses like storm sudden commencement (ssc) and solar flare effect (sfe) in the geomagnetic field variations. For the moderate geomagnetic storm that occurred on 17 February 1993, with a minimum Dst index of −110 nT, the geo-electric field responses to the impulse around 11:00 LT at LAM are Ex = 520 mV km−1 and Ey = 400 mV km−1. The geo-electric field responses to the sfe that occurred around 14:30 LT on 4 April 1993 are clearly observed at different stations as well. At LAM the crest-to-crest amplitude of the geo-electric field components associated with the sfe are Ex = 550 mV km−1 and Ey = 340 mV km−1. Note that the sfe impact on the geo-electric field variations decreases with the increasing distance of the stations from the subsolar point, which is located at about 5.13° N on 4 April. This trend does not reflect the sfe increasing amplitude near the dip equator due the high Cowling conductivity in the EEJ belt.