Science.gov

Sample records for active geomagnetic conditions

  1. Impact of active geomagnetic conditions on stimulated radiation during ionospheric second electron gyroharmonic heating

    NASA Astrophysics Data System (ADS)

    Bordikar, M. R.; Scales, W. A.; Mahmoudian, A.; Kim, H.; Bernhardt, P. A.; Redmon, R.; Samimi, A. R.; Brizcinski, S.; McCarrick, M. J.

    2014-01-01

    Recently, narrowband emissions ordered near the H+ (proton) gyrofrequency (fcH) were reported in the stimulated electromagnetic emission (SEE) spectrum during active geomagnetic conditions. This work presents new observations and theoretical analysis of these recently discovered emissions. These emission lines are observed in the stimulated electromagnetic emission (SEE) spectrum when the transmitter is tuned near the second electron gyroharmonic frequency (2fce) during recent ionospheric modification experiments at the High Frequency Active Auroral Research (HAARP) facility near Gakona, Alaska. The spectral lines are typically shifted below and above the pump wave frequency by harmonics of a frequency roughly 10% less than fcH (≈ 800 Hz) with a narrow emission bandwidth less than the O+ gyrofrequency (≈ 50 Hz). However, new observations and analysis of emission lines ordered by a frequency approximately 10% greater than fcH are presented here for the first time as well. The interaction altitude for the heating for all the observations is in the range of 160 km up to 200 km. As described previously, proton precipitation due to active geomagnetic conditions is considered as the reason for the presence of H+ ions known to be a minor background constituent in this altitude region. DMSP satellite observations over HAARP during the heating experiments and ground-based magnetometer and riometer data validate active geomagnetic conditions. The theory of parametric decay instability in multi-ion component plasma including H+ ions as a minority species described in previous work is expanded in light of simultaneously observed preexisting SEE features to interpret the newly reported observations. Impact of active geomagnetic conditions on the SEE spectrum as a diagnostic tool for proton precipitation event characterization is discussed.

  2. Reconstruction of Geomagnetic activity and near-Earth interplanetary conditions over the past 167 years.

    NASA Astrophysics Data System (ADS)

    Lockwood, Mike; Nevanlinna, Heikki; Barnard, Luke; Owens, Mat; Harrison, Giles; Rouillard, Alexis; Scott, Chris; Vokhmyanin, Mikhail; Ponyavin, Dmitri; Sokolov, Sergey

    2014-05-01

    Records of geomagnetic activity have previously been used to reconstruct the conditions in near-Earth space, such as the interplanetary magnetic field (IMF), solar wind speed (Vsw) and open solar flux (OSF). Reliable geomagnetic activity records exist back until the mid-1800's, and these data provide one of the few means of inferring variations in the conditions in near-Earth space before the advent of the space age. However, there are challenges in using geomagnetic activity records to reconstruct interplanetary conditions. In particular it is necessary to ensure, as best as is possible, the homogeneity and reliability of any geomagnetic indices used. This becomes increasingly difficult further back in history, as both the quality of the data and the number of observing stations decreases. A new geomagnetic activity index, the IDV(1D) index, is presented, which is designed to be as homogeneous in its construction as possible (Lockwood et al. 2013a). This is achieved by only combining data that, by virtue of the locations of the source observatories used, have similar responses to solar wind and IMF variations. IDV(1d) employs many of the principles of the IDV index (Svalgaard and Cliver (2010)), inspired by the u index of Bartels (1932). The index uses interdiurnal variation data from Helsinki for 1845- 1890 and 1893-1896 and from Eskdalemuir from 1911 to the present. The gaps are filled using data from the Potsdam (1891-1892 and 1897-1907) and the nearby Seddin observatories (1908-1910) and intercalibration achieved using the Potsdam-Seddin sequence. The index is compared with independent, early data from European-sector stations, as well as the composite u index and the IDV index. Agreement is found to be extremely good in most cases. IDV(1D) does not suffer from the poor homogeneity of the IDV index, and is more highly correlated with the IMF, consequently it yields a more reliable reconstruction (Lockwood et al 2013b). For completeness, we use 4 different

  3. Field-Aligned Current Sheet Motion and Its Correlation with Solar Wind Conditions and Geomagnetic Activities

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Le, G.; Boardsen, S. A.; Slavin, J. A.; Strangeway, R. J.

    2008-05-01

    Field-aligned currents (FACs) are the currents flowing into and out of the ionosphere which connect to the magnetosphere. They provide an essential linkage between the solar wind - magnetosphere system and the ionosphere, and the understanding of these currents is important for global magnetosphere dynamics and space weather prediction. The three spacecraft ST-5 constellation provides an unprecedented opportunity to study in situ FAC dynamics in time scales (10 sec to 10 min) that can not be achieved previously with single spacecraft studies or large-spaced conjugate spacecraft studies. In this study, we use the magnetic field observations during the whole ST-5 mission and their corresponding solar wind conditions to study the dependence of FAC current sheet motion and intensity on solar wind conditions. FAC peak current densities show very good correlations with some solar wind parameters, including IMF Bz, dynamic pressure, Ey, and some IMF angles, but not with other parameters. Instant FAC speeds show generally much weaker dependence on solar wind conditions comparing to FAC peak current densities. This obvious uncorrelation between FAC peak current densities and speeds implies that FAC peak current densities are more consistently controlled by solar wind conditions and geomagnetic activities, while FAC speeds are more oscillatory, sometimes with higher speeds during quieter times and lower speeds during more turbulent times.

  4. Field-Aligned Current Dynamics and Its Correlation with Solar Wind Conditions and Geomagnetic Activities From Space Technology 5 Observations

    NASA Astrophysics Data System (ADS)

    Wang, Yongli; Boardsen, Scott; Le, Guan; Slavin, James; Strangeway, Robert J.

    Field-aligned currents (FACs) are the currents flowing into and out of the ionosphere which connect to the magnetosphere. They provide an essential linkage between the solar wind - magnetosphere system and the ionosphere, and the understanding of these currents is important for global magnetosphere dynamics and space weather prediction. The three spacecraft ST-5 constellation provides an unprecedented opportunity to study in situ FAC dynamics in time scales (10 sec to 10 min) that can not be achieved previously with single spacecraft studies or large-spaced conjugate spacecraft studies. In this study, we use the magnetic field observations during the whole ST-5 mission to study the dependence of FAC current sheet motion and intensity on solar wind conditions. FAC peak current densities show very good correlations with some solar wind parameters, including IMF Bz, dynamic pressure, Ey, and some IMF angles, but not with other parameters. Instant FAC speeds show generally much weaker dependence on solar wind conditions comparing to FAC peak current densities. This obvious uncorrelation between FAC peak current densities and speeds implies that FAC peak current densities are more consistently controlled by solar wind conditions and geomagnetic activities, while FAC speeds are more oscillatory, sometimes with higher speeds during quieter times and lower speeds during more turbulent times. Detailed examination of FAC current sheet speed during two major storms in the ST-5 mission will also be given to illustrate the temporal evolution of the FAC dynamics with geomagnetic storm.

  5. Tsunami related to solar and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2016-04-01

    The authors of this study wanted to verify the existence of a correlation between earthquakes of high intensity capable of generating tsunami and variations of solar and Earth's geomagnetic activity. To confirming or not the presence of this kind of correlation, the authors analyzed the conditions of Spaceweather "near Earth" and the characteristics of the Earth's geomagnetic field in the hours that preceded the four earthquakes of high intensity that have generated tsunamis: 1) Japan M9 earthquake occurred on March 11, 2011 at 05:46 UTC; 2) Japan M7.1 earthquake occurred on October 25, 2013 at 17:10 UTC; 3) Chile M8.2 earthquake occurred on April 1, 2014 at 23:46 UTC; 4) Chile M8.3 earthquake occurred on September 16, 2015 at 22:54 UTC. The data relating to the four earthquakes were provided by the United States Geological Survey (USGS). The data on ion density used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density of three different energy fractions: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV). Geomagnetic activity data were provided by Tromsø Geomagnetic Observatory (TGO), Norway; by Scoresbysund Geomagnetic Observatory (SCO), Greenland, Denmark and by Space Weather Prediction Center of Pushkov Institute of terrestrial magnetism, ionosphere and radio wave propagation (IZMIRAN), Troitsk, Moscow Region. The results of the study, in agreement with what already

  6. Dependences of statistical characteristics of NmE on the month of the year at middle and low latitudes under daytime geomagnetically quiet conditions at low solar activity

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.; Pavlova, N. M.

    2016-07-01

    Month-to-month changes in the statistical characteristics of the ionospheric E layer peak electron density NmE at medium and low geomagnetic latitudes under daytime geomagnetically quiet conditions are investigated. Critical frequencies of the ionospheric E layer measured by the middle latitude ionosonde Boulder and low latitude ionosondes Huancayo and Jicamarca at low solar activity from 1957 to 2015 have been used in the conducted statistical analysis. The mathematical expectation of NmE, standard deviation of NmE from the expectation of NmE, and NmE variation coefficient have been calculated for each month of the year. The months of the formation of extrema of these statistical parameters of NmE were found.

  7. Range indices of geomagnetic activity

    USGS Publications Warehouse

    Stuart, W.F.; Green, A.W.

    1988-01-01

    The simplest index of geomagnetic activity is the range in nT from maximum to minimum value of the field in a given time interval. The hourly range R was recommended by IAGA for use at observatories at latitudes greater than 65??, but was superceded by AE. The most used geomagnetic index K is based on the range of activity in a 3 h interval corrected for the regular daily variation. In order to take advantage of real time data processing, now available at many observatories, it is proposed to introduce a 1 h range index and also a 3 h range index. Both will be computed hourly, i.e. each will have a series of 24 per day, the 3 h values overlapping. The new data will be available as the range (R) of activity in nT and also as a logarithmic index (I) of the range. The exponent relating index to range in nT is based closely on the scale used for computing K values. The new ranges and range indices are available, from June 1987, to users in real time and can be accessed by telephone connection or computer network. Their first year of production is regarded as a trial period during which their value to the scientific and commercial communities will be assessed, together with their potential as indicators of regional and global disturbances' and in which trials will be conducted into ways of eliminating excessive bias at quiet times due to the rate of change of the daily variation field. ?? 1988.

  8. Geomagnetic activity: Dependence on solar wind parameters

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1977-01-01

    Current ideas about the interaction between the solar wind and the earth's magnetosphere are reviewed. The solar wind dynamic pressure as well as the influx of interplanetary magnetic field lines are both important for the generation of geomagnetic activity. The influence of the geometry of the situation as well as the variability of the interplanetary magnetic field are both found to be important factors. Semi-annual and universal time variations are discussed as well as the 22-year cycle in geomagnetic activity. All three are found to be explainable by the varying geometry of the interaction. Long term changes in geomagnetic activity are examined.

  9. Heart attacks and geomagnetic activity.

    PubMed

    Knox, E G; Armstrong, E; Lancashire, R; Wall, M; Haynes, R

    1979-10-18

    Malin and Srivastava reported a remarkable correlation between daily variations in the geomagnetic field strength and daily admissions to the cardio-thoracic wards of hospitals in Hyderabad and Secunderabad, for cardiac emergencies, during 1967--72. We have now carried out a similar enquiry in the West Midlands region of the UK for the years 1969--70, but were unable to confirm the Indian results.

  10. Geomagnetic Activity Forecast based on SW-M-I coupling

    NASA Astrophysics Data System (ADS)

    Nagatsuma, T.

    2009-12-01

    The geomagnetic activity shows diurnal and semiannual and solar cycle variations. The cause of these variations consists of two effects. One is the periodical change of the solar wind parameters due to a variation of the geometrical condition between the solar wind and the Earth’s magnetosphere. The other is the periodical change of the SW-M-I coupling efficiency caused by the changing of ionospheric conductivity in the polar cap region. Therefore, operational forecasting model of geomagnetic activity should take into account these variations and dependence. We have developed the empirical model for forecasting geomagnetic activity considering the change of the SW-M-I coupling efficiency. This model can reproduce Equinoctial effect and solar cycle dependence of geomagnetic activity. Further, we have found that the efficiency of SW-M-I coupling tend to be low during the low Alfven Mach number period, from the event analysis of Nov. 2003 storm. Also, we have found that the Alfven Mach number dependence exists independently form the solar wind electric field dependence based on the statistical analysis of PCN index. Since the condition of low Alfven Mach number tend to occur within the ICMEs, we are developing the empirical model with considering the Alfven Mach number dependence. We expect this modification will improve the prediction of severe geomagnetic storm. We also try to examine that our model is valid during the period of recent few years of quiet solar activity.

  11. Long-term monthly statistics of mid-latitudinal NmF2 in the Northern geographic hemisphere during geomagnetically quiet and steadily low solar activity conditions

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    2016-07-01

    Long-term mid-latitude hourly values of NmF2 measured in 1957-2015 by 10 ionosondes (Point Arguello, Wallops Is., Boulder, de l'Ebre, Rome, Ottawa, Pruhonice, Dourbes, Slough, and Juliusruh) in the Northern geographic hemisphere were processed to select periods of geomagnetically quiet and low solar activity conditions to calculate several descriptive statistics of the noon NmF2 for each month, including the mathematical expectation, most probable value, arithmetic average, and arithmetic average median. The month-to-month variability of these descriptors allowed us to identify months of a year when they reach their extremes (maxima, minima). The calculated month-to-month variations of the NmF2 statistical parameters made it possible to study the winter anomaly and spring-autumn asymmetry in these statistical parameters.

  12. Long-term monthly statistics of mid-latitudinal NmF2 in the northern geographic hemisphere during geomagnetically quiet and steadily low solar activity conditions

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.; Pavlova, N. M.

    2016-05-01

    Long-term mid-latitude hourly values of NmF2 measured in 1957-2015 by 10 ionosondes in the Northern geographic hemisphere were processed to select periods of geomagnetically quiet and low solar activity conditions to calculate several descriptive statistics of the noon NmF2 for each month, including the mathematical expectation, most probable value, arithmetic average, and arithmetic average median. The month-to-month variability of these descriptors allowed us to identify months of a year when they reach their extremes (maxima, minima). The calculated month-to-month variations of the NmF2 statistical parameters made it possible to study the winter anomaly and spring-autumn asymmetry in these statistical parameters.

  13. Review of selected geomagnetic activity indices

    NASA Technical Reports Server (NTRS)

    Allen, J. H.; Feynman, J.

    1979-01-01

    Magnetic activity indexes are reviewed. Classifications of magnetograms from single observatories and the global range of potential associated with the equivalent currents which could have produced the variations monitored at a large array of recording sides are addressed. Principal magnetic activity indexes discussed include: the auroral electrojet index and its associated indexes (AU, AL and AO) useful for auroral zone studies; the Kp, ap, aa and am indexes which are measures of midlatitude geomagnetic activity; and the Dst index of magnetic activity recorded at low latitudes. It is concluded that geomagnetic activity indexes are useful in studies of the interaction between solar activity, the interplanetary magnetic field and solar wind, the magnetosphere, ring current, field aligned currents, and ionospheric currents.

  14. Relationships of high-latitude geomagnetic variations to interplanetary plasma conditions

    SciTech Connect

    Wolfe, A. AT T Bell Laboratories, Murray Hill, NJ ); Lanzerotti, L.J.; Maclennan, C.G.; Medford, L.V. )

    1987-01-01

    As an extension of the United States program at South Pole Station to study in detail the southern magnetospheric cusp region, the authors have initiated geomagnetic studies at Iqaluit (formerly Frobisher Bay), Baffin Island, Northwest Territories, Canada. This location is approximately geomagnetically conjugate to South Pole Station under quiet geomagnetic conditions. Both sites are just inside the equatorward boundary of the dayside magnetospheric cusps in their respective hemispheres. This research includes studies of the conjugacy of geometric activity at these high latitudes, studies of the conditions under which conjugacy breaks down, and the relationship of geomagnetic variations to energy sources in the interplanetary plasma. In both hemispheres, variations in the magnetic field are measured with fluxgate magnetometers over the range from 0.0 to approximately 0.5 hertz. The field variations are measured in three orthogonal components: Geomagnetic north-south (H-component), geomagnetic east-west (D-component), and vertical (V-component). The magnetic field data are analyzed using a number of statistical techniques, including power spectra analysis. Presented here are the results of a study of hourly power spectra computed for the the H-component magnetic field data acquired at both South Pole and Iqaluit for the 30-day interval 17 July to 15 August 1985. After computing the spectra, the geomagnetic power is calculated over several different bandwidths corresponding, roughly, to frequencies related to hydromagnetic waves in the Earth's magnetosphere.

  15. Forecasting Geomagnetic Conditions in near-Earth space

    NASA Astrophysics Data System (ADS)

    Abunina, M.; Papaioannou, A.; Gerontidou, M.; Paschalis, P.; Abunin, A.; Gaidash, S.; Tsepakina, I.; Malimbayev, A.; Belov, A.; Mavromichalaki, H.; Kryakunova, O.; Velinov, P.

    2013-02-01

    Geomagnetic conditions in near-Earth space have been a constantly evolving scientific field, especially during the latest years when the dependence of our everyday life on space environment has significantly increased. The scientific community managed to implement centers for the continuous monitoring of the geomagnetic conditions which resulted into short and long term forecasting of the planetary geomagnetic index Ap. In this work, the centers that have been established and are in operational mode in Russia (IZMIRAN), Greece (Athens), Kazakhstan (Almaty) and Bulgaria (Sofia) are presented. The methods that have been used for the forecasting of Ap index are demonstrated and the forecasted results in comparison to the actual Ap measurements are also discussed.

  16. Influence of Geomagnetic and IMF conditions on High Latitude Upper Atmospheric winds and Temperatures

    NASA Astrophysics Data System (ADS)

    Dhadly, M. S.; Conde, M.; Emmert, J. T.

    2015-12-01

    We analyzed the climatological behavior of upper atmospheric winds (horizontal and vertical) and temperatures above Alaska by combining line-of-sight Doppler shifts of 630 nm optical emissions recorded during the 2011 and 2012 winters using a ground based all-sky wavelength scanning Doppler Fabry-Perot interferometer (SDI) located at Poker Flat (65.12N, 147.47W). The wide field of view covered a large geographic region above Alaska. This field was divided in software into multiple zones (115 used here), allowing independent spectra to be sampled from many directions simultaneously. As a result, it is capable of recording the wind field's spatial variations over a wide geographic region with high spatial resolution, and to resolve these variations over time. Although such climatological studies have been performed previously using satellites, models, and narrow field Fabry-Perot interferometers, there are no published climatological studies of thermospheric winds and temperatures using either SDI data or any other technique with comparable geographic coverage and resolution. Wind summary dial plots were produced to depict the climatology of the horizontal winds and temperatures for different geomagnetic conditions and orientation of interplanetary magnetic field (IMF). Results show that horizontal winds and temperatures had a strong dependence on geospace activity and orientation of IMF. The latitudinal shears in horizontal winds were stronger when geomagnetic conditions were active compared to the latitudinal shears for quiet conditions. Also, shears appeared earlier over Poker Flat when geomagnetic conditions were active. The latitudinal shears showed more dependence on IMF when geomagnetic conditions were active than they did during quieter conditions. F-region temperatures were higher under active geomagnetic conditions than during quiet conditions. They were also observed to be higher in pre-magnetic midnight sector (duskside) than they were post

  17. Forecasts of solar and geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Joselyn, Joann

    1987-01-01

    Forecasts of solar and geomagnetic activity are critical since these quantities are such important inputs to the thermospheric density models. At this time in the history of solar science there is no way to make such a forecast from first principles. Physical theory applied to the Sun is developing rapidly, but is still primitive. Techniques used for forecasting depend upon the observations over about 130 years, which is only twelve solar cycles. It has been noted that even-numbered cycles systematically tend to be smaller than the odd-numbered ones by about 20 percent. Another observation is that for the last 12 cycle pairs, an even-numbered sunspot cycle looks rather like the next odd-numbered cycle, but with the top cut off. These observations are examples of approximate periodicities that forecasters try to use to achieve some insight into the nature of an upcoming cycle. Another new and useful forecasting aid is a correlation that has been noted between geomagnetic indices and the size of the next solar cycle. Some best estimates are given concerning both activities.

  18. Solar activity geomagnetic field and terrestrial weather

    NASA Technical Reports Server (NTRS)

    Knight, J. W.; Sturrock, P. A.

    1976-01-01

    Spectral analysis is used as an independent test of the reported association between interplanetary-magnetic-field structure and terrestrial weather. Spectra of the Ap geomagnetic activity index and the vorticity area index for the years from 1964 to 1970 are examined for common features that may be associated with solar-related phenomena, specifically for peaks in the power spectra of both time series with periods near 27.1 days. The spectra are compared in three ways, and the largest peak with the smallest probability estimate is found to occur at a period of 27.49 days. This result is considered to be statistically significant at the 98% level. It is concluded that the period derived from the Ap spectrum is related to solar rotation and that the analysis provides supporting evidence for a connection between the vorticity area index and solar activity.

  19. Forecasting geomagnetic activities from the Boyle Index

    NASA Astrophysics Data System (ADS)

    Bala, R.; Reiff, P. H.

    2010-12-01

    The Boyle Index (BI), Φ =10-4}( {v{2}/{km/sec) + 11.7({(B)/(nT)})sin 3}{(θ /2) kV, has been successful in predicting the geomagnetic activity since its inception in October 2003. It is available in near-real-time from http://space.rice.edu/ISTP/wind.html and provides space weather predictions of geomagnetic indices (Kp, Dst and the AE) in real time through neural network algorithms. In addition, it provides free email alerts to its 700+ subscribers whenever the magnetospheric activity levels exceed certain pre-defined thresholds. We are constantly improving our algorithms, in the interest of either including more data or improving the accuracy and lead-time of forecasts. For example, with the inclusion of two more years of data (2008 and 2009) in the training, we have the advantage of modeling one of the deepest solar minimums, which has been exceptionally low in terms of the activity level. Our algorithms have been successful in capturing the effects of ``preconditioning" and the non-linearity in the solar wind parameters (for example, see figure 1). This paper presents our new attempts to include the effects of solar turbulence by incorporating the standard deviations in the solar wind parameters along with the BI, for greater the turbulence the higher the energy input into the magnetosphere as some of the previous studies have shown. Furthermore, we will also present how 3-hour averaged 1-hour sliding window scheme have improved our predictions with lead times of 3 hours or longer. Our predictions from a recent activity, 03 August 2010.

  20. Is motivation influenced by geomagnetic activity?

    PubMed

    Starbuck, S; Cornélissen, G; Halberg, F

    2002-01-01

    To eventually build a scientific bridge to religion by examining whether non-photic, non-thermic solar effects may influence (religious) motivation, invaluable yearly world wide data on activities from 1950 to 1999 by Jehovah's Witnesses on behalf of their church were analyzed chronobiologically. The time structure (chronome) of these archives, insofar as it is able to be evaluated in yearly means for up to half a century, was assessed. Least squares spectra in a frequency range from one cycle in 42 to one in 2.1 years of data on the average number of hours per month spent in work for the church, available from 103 different geographic locations, as well as grand totals also including other sites, revealed a large peak at one cycle in about 21 years. The non-linear least squares fit of a model consisting of a linear trend and a cosine curve with a trial period of 21.0 years, numerically approximating that of the Hale cycle, validated the about 21.0-year component in about 70% of the data series, with the non-overlap of zero by the 95% confidence interval of the amplitude estimate. Estimates of MESOR (midline-estimating statistic of rhythm, a rhythm (or chronome) adjusted mean), amplitude and period were further regressed with geomagnetic latitude. The period estimate did not depend on geomagnetic latitude. The about 21.0-year amplitude tends to be larger at low and middle than at higher latitudes and the resolution of the about 21.0-year cycle, gauged by the width of 95% confidence intervals for the period and amplitude, is higher (the 95% confidence intervals are statistically significantly smaller) at higher than at lower latitudes. Near-matches of periods in solar activity and human motivation hint that the former may influence the latter, while the dependence on latitude constitutes evidence that geomagnetic activity may affect certain brain areas involved in motivation, just as it was earlier found that it is associated with effects on the electrocardiogram

  1. Major geomagnetic storm due to solar activity (2006-2013).

    NASA Astrophysics Data System (ADS)

    Tiwari, Bhupendra Kumar

    Major geomagnetic storm due to solar activity (2006-2013). Bhupendra Kumar Tiwari Department of Physics, A.P.S.University, Rewa(M.P.) Email: - btiwtari70@yahoo.com mobile 09424981974 Abstract- The geospace environment is dominated by disturbances created by the sun, it is observed that coronal mass ejection (CME) and solar flare events are the causal link to solar activity that produces geomagnetic storm (GMS).CMEs are large scale magneto-plasma structures that erupt from the sun and propagate through the interplanetary medium with speeds ranging from only a few km/s to as large as 4000 km/s. When the interplanetary magnetic field associated with CMEs impinges upon the earth’s magnetosphere and reconnect occur geomagnetic storm. Based on the observation from SOHO/LASCO spacecraft for solar activity and WDC for geomagnetism Kyoto for geomagnetic storm events are characterized by the disturbance storm time (Dst) index during the period 2006-2013. We consider here only intense geomagnetic storm Dst <-100nT, are 12 during 2006-2013.Geomagnetic storm with maximum Dst< -155nT occurred on Dec15, 2006 associated with halo CME with Kp-index 8+ and also verify that halo CME is the main cause to produce large geomagnetic storms.

  2. Loss of Geosynchronous Relativistic Electrons By Emic Wave Scattering Under Quiet Geomagnetic Conditions

    NASA Astrophysics Data System (ADS)

    Kim, K. H.; Hyun, K.; Lee, E.; Lee, D. H.

    2014-12-01

    We have examined relativistic electron flux losses at geosynchronous orbit under quiet geomagnetic conditions. One 3-day period, from 11 to 13 October 2007, was chosen for analysis because geomagnetic conditions were very quiet (3-day average of Kp < 1), and significant losses of geosynchronous relativistic electrons were observed. During this interval, there was no geomagnetic storm activity. Thus, the loss processes associated with geomagnetic field modulations caused by ring current buildup can be excluded. The >2 MeV electron flux at geosynchronous orbit shows typical diurnal variations with a maximum near noon and a minimum near midnight for each day. The flux level of the daily variation significantly decreased from first day to third day for the 3-day period by a factor of >10. The total magnetic field strength (BT) of the daily variation on the third day, however, is comparable to that on the first day. Unlike electron flux decreases, the flux of protons with energies between 0.8 and 4 MeV adiabatically responses to the daily variation of BT. That is, there is no significant decrease of the proton flux when the electron flux decreases. During the interval of quiet geomagnetic conditions, well-defined electromagnetic ion cyclotron (EMIC) waves were detected at geosynchronous spacecraft. Low-altitude polar orbiting spacecraft observed the precipitation of energetic protons and relativistic electrons in the interval of EMIC waves enhancement. From these observations, we suggest that the EMIC waves at geosynchronous orbit cause pitch-angle scattering and electron loss to the atmosphere under quiet geomagnetic conditions.

  3. Loss of geosynchronous relativistic electrons by EMIC wave scattering under quiet geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Hyun, K.; Kim, K.-H.; Lee, E.; Kwon, H.-J.; Lee, D.-H.; Jin, H.

    2014-10-01

    We have examined relativistic electron flux losses at geosynchronous orbit under quiet geomagnetic conditions. One 3 day period, from 11 to 13 October 2007, was chosen for analysis because geomagnetic conditions were very quiet (3 day average of Kp< 1), and significant losses of geosynchronous relativistic electrons were observed. During this interval, there was no geomagnetic storm activity. Thus, the loss processes associated with geomagnetic field modulations caused by ring current buildup can be excluded. The >2 MeV electron flux at geosynchronous orbit shows typical diurnal variations with a maximum near noon and a minimum near midnight for each day. The flux level of the daily variation significantly decreased from first day to third day for the 3 day period by a factor of >10. The total magnetic field strength (BT) of the daily variation on the third day, however, is comparable to that on the first day. Unlike electron flux decreases, the flux of protons with energies between 0.8 and 4 MeV adiabatically responses to the daily variation of BT. That is, there is no significant decrease of the proton flux when the electron flux decreases. During the interval of quiet geomagnetic conditions, well-defined electromagnetic ion cyclotron (EMIC) waves were detected at geosynchronous spacecraft. Low-altitude polar-orbiting spacecraft observed the precipitation of energetic protons and relativistic electrons in the interval of EMIC waves enhancement. From these observations, we suggest that the EMIC waves at geosynchronous orbit cause pitch angle scattering and relativistic electron losses to the atmosphere under quiet geomagnetic conditions.

  4. Periodic substorm activity in the geomagnetic tail

    NASA Technical Reports Server (NTRS)

    Huang, C. Y.; Eastman, T. E.; Frank, L. A.; Williams, D. J.

    1983-01-01

    On 19 May 1978 an anusual series of events is observed with the Quadrispherical LEPEDEA on board the ISEE-1 satellite in the Earth's geomagnetic tail. For 13 hours periodic bursts of both ions and electrons are seen in all the particle detectors on the spacecraft. On this day periodic activity is also seen on the ground, where multiple intensifications of the electrojets are observed. At the same time the latitudinal component of the interplanetary magnetic field shows a number of strong southward deflections. It is concluded that an extended period of substorm activity is occurring, which causes repeated thinnings and recoveries of the plasma sheet. These are detected by ISEE, which is situated in the plasma sheet boundary layer, as periodic dropouts and reappearances of the plasma. Comparisons of the observations at ISEE with those at IMP-8, which for a time is engulfed by the plasma sheet, indicate that the activity is relatively localized in spatial extent. For this series of events it is clear that a global approach to magnetospheric dynamics, e.g., reconnection, is inappropriate.

  5. Solar Activity, Different Geomagnetic Activity Levels and Acute Myocardial Infarction

    NASA Astrophysics Data System (ADS)

    Dimitrova, Svetla; Jordanova, Malina; Stoilova, Irina; Taseva, Tatiana; Maslarov, Dimitar

    Results on revealing a possible relationship between solar activity (SA) and geomagnetic activity (GMA) and acute myocardial infarction (AMI) morbidity are presented. Studies were based on medical data covering the period from 1.12.1995 to 31.12.2004 and concerned daily distribution of patients with AMI diagnose (in total 1192 cases) from Sofia region on the day of admission at the hospital. Analysis of variance (ANOVA) was applied to check the significance of GMA intensity effect and the type of geomagnetic storms, those caused by Magnetic Clouds (MC) and by High Speed Solar Wind Streams (HSSWS), on AMI morbidity. Relevant correlation coefficients were calculated. Results revealed statistically significant positive correlation between considered GMA indices and AMI. ANOVA revealed that AMI number was signifi- cantly increased from the day before (-1st) till the day after (+1st) geomagnetic storms with different intensities. Geomagnetic storms caused by MC were related to significant increase of AMI number in comparison with the storms caused by HSSWS. There was a trend for such different effects even on -1st and +1st day.

  6. Solar wind turbulence as a driver of geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Ikechukwu Ugwu, Ernest Benjamin; Nneka Okeke, Francisca; Ugonabo, Obiageli Josephine

    2016-07-01

    We carried out simultaneous analyses of interplanetary and geomagnetic datasets for the period of (solar Maunder) least (2009) and maximum (2002) solar activity to determine the nature of solar wind turbulence on geomagnetic activity using AE, ASY-D, and ASY-H indices. We determined the role played by Alfvénic fluctuations in the solar wind so as to find out the nature of the turbulence. Our analyses showed that solar wind turbulence play a role in geomagnetic processes at high latitudes during periods of low and high solaractivity but does not have any effect at mid-low latitudes.

  7. A Study on local geomagnetic activity trend and singularity with geomagnetic data at Cheongyang Magnetic Observatory, Korea

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Jeon, Y.; Ryoo, S.

    2011-12-01

    The KMA(Korea Meteorological Administration) has installed and operated the geomagnetic observatory at Cheongyang-gun, Chungcheongnam-do, Korea which started in April, 2009. As Cheongyang geomagnetic observatory, it has been automatically observing total-, X-, Y- and Z-component data at 1-sec interval and storing in real-time. The National Institute of Meteorological Research, which belongs to KMA, proceeded with their work on the production of K-index that is used for geomagnetic activity observation. In addition, we detect the starting and ending of geomagnetic storm as typical thing of global geomagnetic field change and utilize it for showing current status of geomagnetic storm occurrence. It has been reported that geomagnetic storm occurred seven times during from April, 2010 to July, 2011. It was 5 of the maximum K-index value during geomagnetic storm occurrence period and thought mostly to have been caused by coronal hole and CME(Coronal Mass Ejection). Yet the geomagnetic storm has not been had much of an impact locally. At Cheongyang Observatory, a significantly disturbed geomagnetic data was seen as related to the Tohoku, Japan Earthquake, Mw 9.0, on March 11, 2011. Compared to seismic wave data at Seosan seismic observatory 60km away from Cheongyang geomagnetic observatory, we identified the signal involved to the Tohoku, Japan Earthquake. The power spectral density of the disturbed signal has the dominant frequency band of about 0.05 to 0.1 Hz. We should proceed additional study about this in detail.

  8. Thermosphere Response to Geomagnetic Variability during Solar Minimum Conditions

    NASA Astrophysics Data System (ADS)

    Forbes, Jeffrey; Gasperini, Federico; Zhang, Xiaoli; Doornbos, Eelco; Bruinsma, Sean; Haeusler, Kathrin; Hagan, Maura

    2015-04-01

    The response of thermosphere mass density to variable geomagnetic activity at solar minimum is revealed as a function of height utilizing accelerometer data from GRACE near 480 km, CHAMP near 320 km, and GOCE near 260 km during the period October-December, 2009. The GOCE data at 260 km, and to some degree the CHAMP measurements at 320 km, reveal the interesting feature that the response maximum occurs at low latitudes, rather than at high latitudes where the geomagnetic energy input is presumed to be deposited. The latitude distribution of the response is opposite to what one might expect based on thermal expansion and/or increase in mean molecular weight due to vertical transport of N2 at high latitudes. We speculate that what is observed reflects the consequences of an equatorward meridional circulation with downward motion and compressional heating at low latitudes. A numerical simulation using the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM) is used to assist with this diagnosis. At 480 km GRACE reveals maximum density responses at high southern (winter) latitudes, consistent with recent interpretations in terms of compositional versus temperature effects near the oxygen-helium transition altitude during low solar activity.

  9. Geomagnetic activity and polar surface air temperature variability

    NASA Astrophysics Data System (ADS)

    Seppälä, A.; Randall, C. E.; Clilverd, M. A.; Rozanov, E.; Rodger, C. J.

    2009-10-01

    Here we use the ERA-40 and ECMWF operational surface level air temperature data sets from 1957 to 2006 to examine polar temperature variations during years with different levels of geomagnetic activity, as defined by the A p index. Previous modeling work has suggested that NO x produced at high latitudes by energetic particle precipitation can eventually lead to detectable changes in surface air temperatures (SATs). We find that during winter months, polar SATs in years with high A p index are different than in years with low A p index; the differences are statistically significant at the 2-sigma level and range up to about ±4.5 K, depending on location. The temperature differences are larger when years with wintertime Sudden Stratospheric Warmings (SSWs) are excluded. We take into account solar irradiance variations, unlike previous analyses of geomagnetic effects in ERA-40 and operational data. Although we cannot conclusively show that the polar SAT patterns are physically linked by geomagnetic activity, we conclude that geomagnetic activity likely plays a role in modulating wintertime surface air temperatures. We tested our SAT results against variation in the Quasi Biennial Oscillation, the El Niño Southern Oscillation and the Southern Annular Mode. The results suggested that these were not driving the observed polar SAT variability. However, significant uncertainty is introduced by the Northern Annular Mode, and we cannot robustly exclude a chance linkage between sea surface temperature variability and geomagnetic activity.

  10. Secular trends in storm-level geomagnetic activity

    USGS Publications Warehouse

    Love, J.J.

    2011-01-01

    Analysis is made of K-index data from groups of ground-based geomagnetic observatories in Germany, Britain, and Australia, 1868.0-2009.0, solar cycles 11-23. Methods include nonparametric measures of trends and statistical significance used by the hydrological and climatological research communities. Among the three observatory groups, German K data systematically record the highest disturbance levels, followed by the British and, then, the Australian data. Signals consistently seen in K data from all three observatory groups can be reasonably interpreted as physically meaninginful: (1) geomagnetic activity has generally increased over the past 141 years. However, the detailed secular evolution of geomagnetic activity is not well characterized by either a linear trend nor, even, a monotonic trend. Therefore, simple, phenomenological extrapolations of past trends in solar and geomagnetic activity levels are unlikely to be useful for making quantitative predictions of future trends lasting longer than a solar cycle or so. (2) The well-known tendency for magnetic storms to occur during the declining phase of a sunspot-solar cycles is clearly seen for cycles 14-23; it is not, however, clearly seen for cycles 11-13. Therefore, in addition to an increase in geomagnetic activity, the nature of solar-terrestrial interaction has also apparently changed over the past 141 years. ?? Author(s) 2011.

  11. The geomagnetic cutoff rigidities at high latitudes for different solar wind and geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Chu, W.; Qin, G.

    2016-01-01

    Studying the access of the cosmic rays (CRs) into the magnetosphere is important to understand the coupling between the magnetosphere and the solar wind. In this paper we numerically studied CRs' magnetospheric access with vertical geomagnetic cutoff rigidities using the method proposed by Smart and Shea (1999). By the study of CRs' vertical geomagnetic cutoff rigidities at high latitudes we obtain the CRs' window (CRW) whose boundary is determined when the vertical geomagnetic cutoff rigidities drop to a value lower than a threshold value. Furthermore, we studied the area of CRWs and found out they are sensitive to different parameters, such as the z component of interplanetary magnetic field (IMF), the solar wind dynamic pressure, AE index, and Dst index. It was found that both the AE index and Dst index have a strong correlation with the area of CRWs during strong geomagnetic storms. However, during the medium storms, only AE index has a strong correlation with the area of CRWs, while Dst index has a much weaker correlation with the area of CRWs. This result on the CRW can be used for forecasting the variation of the cosmic rays during the geomagnetic storms.

  12. Statistical analysis and verification of 3-hourly geomagnetic activity probability predictions

    NASA Astrophysics Data System (ADS)

    Wang, Jingjing; Zhong, Qiuzhen; Liu, Siqing; Miao, Juan; Liu, Fanghua; Li, Zhitao; Tang, Weiwei

    2015-12-01

    The Space Environment Prediction Center (SEPC) has classified geomagnetic activity into four levels: quiet to unsettled (Kp < 4), active (Kp = 4), minor to moderate storm (Kp = 5 or 6), and major to severe storm (Kp > 6). The 3-hourly Kp index prediction product provided by the SEPC is updated half hourly. In this study, the statistical conditional forecast models for the 3-hourly geomagnetic activity level were developed based on 10 years of data and applied to more than 3 years of data, using the previous Kp index, interplanetary magnetic field, and solar wind parameters measured by the Advanced Composition Explorer as conditional parameters. The quality of the forecast models was measured and compared against verifications of accuracy, reliability, discrimination capability, and skill of predicting all geomagnetic activity levels, especially the probability of reaching the storm level given a previous "calm" (nonstorm level) or "storm" (storm level) condition. It was found that the conditional models that used the previous Kp index, the peak value of BtV (the product of the total interplanetary magnetic field and speed), the average value of Bz (the southerly component of the interplanetary magnetic field), and BzV (the product of the southerly component of the interplanetary magnetic field and speed) over the last 6 h as conditional parameters provide a relative operating characteristic area of 0.64 and can be an appropriate predictor for the probability forecast of geomagnetic activity level.

  13. Low-latitude Pi2 pulsations during intervals of quiet geomagnetic conditions (Kp≤1)

    NASA Astrophysics Data System (ADS)

    Kwon, H.-J.; Kim, K.-H.; Jun, C.-W.; Takahashi, K.; Lee, D.-H.; Lee, E.; Jin, H.; Seon, J.; Park, Y.-D.; Hwang, J.

    2013-10-01

    It has been reported that Pi2 pulsations can be excited under extremely quiet geomagnetic conditions (Kp=0). However, there have been few comprehensive reports of Pi2 pulsations in such a near ground state magnetosphere. To understand the characteristics of quiet-time Pi2 pulsations, we statistically examined Pi2 events observed on the nightside between 1800 and 0600 local time at the low-latitude Bohyun (BOH, L = 1.35) station in South Korea. We chose year 2008 for analysis because geomagnetic activity was unusually low in that year. A total of 982 Pi2 events were identified when Kp≤1. About 80% of the Pi2 pulsations had a period between 110 and 300 s, which significantly differs from the conventional Pi2 period from 40 to 150 s. Comparing Pi2 periods and solar wind conditions, we found that Pi2 periods decrease with increasing solar wind speed, consistent with the result of Troitskaya (1967). The observed wave properties are discussed in terms of plasmaspheric resonance, which has been proposed for Pi2 pulsations in the inner magnetosphere. We also found that Pi2 pulsations occur quasi-periodically with a repetition period of ˜23-38 min. We will discuss what determines such a recurrence time of Pi2 pulsations under quiet geomagnetic conditions.

  14. Statistical Analysis of TEC Enhancements during Geomagnetic Disturbances in Extreme Solar Conditions

    NASA Astrophysics Data System (ADS)

    Su, F.

    2014-12-01

    In the past decades, a remarkable set of comprehensive studies and review articles enriched theresearch of the Earth's ionospheric response to geomagnetic disturbances[Prolss, 1995; Buonsanto,1999; Mendillo, 2006]. However, comparative studies of TEC response during geomagnetic disturbances in solar minimum and solar maximum have not been reported yet. Here we present some new results of TEC enhancements during geomagnetic disturbancesin extreme solar maximum and deep solar minimum. The JPL TEC maps from 12/01/2000 to 12/31/2003 during high solar activity and from 01/01/2007 to 12/31/2010 during low solar activity are used. The deviation of TEC is defined as the differences between TEC and TECq, which represents the 27-day sliding smooth median. The geomagnetic disturbances selected have peaks of geomagnetic index Ap>20. We found that the winter anomaly appears in both extreme solar cycle conditions and has longer-lived patterns than other seasons.The nighttime enhancement is more significant in solar maximum than solar minimum. The mean duration of TEC enhancements is longer in solar minimum than solar maximum. The mean delay at the beginning of positive anomaly responds fastest at around 1500 LT and slowest at around midnight during solar minimum.The mean intensity of enhancements is stronger at higher latitudes and weaker at lower latitudes, and the mean delay is smaller at higher latitudes and larger at lower latitudes in both extreme solar cycle conditions. Acknowledgments: Thiswork was supportedby the National Natural Science Foundation of China under Grants 41204107. We thank JPL and Word Data Center for Geomagnetism at Kyoto University for making available the data. Prolss, G. W., Ionospheric F region storms, in Handbook of Atmospheric Electrodynamics, vol. 2, edited by H. Volland, pp. 195 - 248, CRC Press,Boca Raton, Fla., 1995. Buonsanto, M., Ionospheric storm: A review,Space Science Review, vol. 88, pp. 563 - 601, 1999. Mendillo, M.: Storms in the

  15. Upper Thermosphere Winds and Temperatures in the Geomagnetic Polar Cap: Solar Cycle, Geomagnetic Activity, and Interplanetary Magnetic Field Dependencies

    NASA Technical Reports Server (NTRS)

    Killeen, T. L.; Won, Y.-I.; Niciejewski, R. J.; Burns, A. G.

    1995-01-01

    central polar cap (greater than approx. 80 magnetic latitude) antisunward wind speed is found to be a strong function of both solar and geomagnetic activity. The polar cap temperatures show variations in both solar and geomagnetic activity, with temperatures near 800 K for low K(sub p) and F(sub 10.7) and greater than about 2000 K for high K(sub p) and F(sub 10.7). The observed temperatures are significantly greater than those predicted by the mass spectrometer/incoherent scatter model for high activity conditions. Theoretical analysis based on the NCAR TIGCM indicates that the antisunward upper thermospheric winds, driven by upstream ion drag, basically 'coast' across the polar cap. The relatively small changes in wind velocity and direction within the polar cap are induced by a combination of forcing terms of commensurate magnitude, including the nonlinear advection term, the Coriolis term, and the pressure gradient force term. The polar cap thennospheric thermal balance is dominated by horizontal advection, and adiabatic and thermal conduction terms.

  16. Theoretical effects of geomagnetic activity on thermospheric tides

    SciTech Connect

    Fesen, C.G.; Richmond, A.D.; Roble, R.G.

    1993-09-01

    The theoretical effects of auroral activity on thermospheric tides during equinox solar cycle minimum are investigated using simulations from the National Center for Atmospheric Research thermosphere-ionosphere general circulation model. One set of model runs examined the effects of increasing levels of geomagnetic activity on the neutral horizontal winds and temperatures. A second set of model runs examined the generation of diurnal and semidiurnal waves in the neutral horizontal winds and temperatures by solar forcing, auroral forcing, and waves propagating vertically from the lower atmosphere. The model simulations were made for four levels of geomagnetic activity, parameterized principally by the total hemispheric power index and the potential drop across the polar cap. The resulting neutral horizontal wind and temperature fields were examined at geographic latitudes of 17.5{degrees}N, 42.5{degrees}N, and 67.5{degrees}N at 70{degrees}W longitude. The modeled response to the level of geomagnetic activity varies with altitude and latitude: the effects tend to maximize at high altitudes and high latitudes and penetrate lower in altitude as geomagnetic activity increases. The simulated mean temperatures increase and the mean winds become more southward and westward at all latitudes with increasing auroral activity. In the upper thermosphere, the model diurnal temperature amplitudes decrease with increasing activity, while the diurnal meridional wind amplitudes increase. The modeled semidiurnal winds are strongly affected by the level of geomagnetic activity, while the semidiurnal temperatures are not. Analysis of the second set of model simulations focusing on the generation of the tidal waves indicates that the tidal response to auroral activity is largely determined by the interference between the waves due to upward propagating tides and in situ solar forcing and those generated by the auroral momentum and energy sources. 28 refs., 19 figs.

  17. The risk characteristics of solar and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Podolska, Katerina

    2016-04-01

    The main aim of this contribution is a deeper analysis of the influence of solar activity which is expected to have an impact on human health, and therefore on mortality, in particular civilization and degenerative diseases. We have constructed the characteristics that represent the risk of solar and geomagnetic activity on human health on the basis of our previous analysis of association between the daily numbers of death on diseases of the nervous system and diseases of the circulatory system and solar and geomagnetic activity in the Czech Republic during the years 1994 - 2013. We used long period daily time series of numbers of deaths by cause, long period time series of solar activity indices (namely R and F10.7), geomagnetic indicies (Kp planetary index, Dst) and ionospheric parameters (foF2 and TEC). The ionospheric parameters were related to the geographic location of the Czech Republic and adjusted for middle geographic latitudes. The risk characteristics were composed by cluster analysis in time series according to the phases of the solar cycle resp. the seasonal insolation at mid-latitudes or the daily period according to the impact of solar and geomagnetic activity on mortality by cause of death from medical cause groups of death VI. Diseases of the nervous system and IX. Diseases of the circulatory system mortality by 10th Revision of International Classification of Diseases WHO (ICD-10).

  18. A method of predictions geomagnetic activity based on a coronal model of relations between solar and geomagnetic activities

    NASA Technical Reports Server (NTRS)

    Halenka, J.

    1979-01-01

    A method developed to predict both disturbed and quiet geomagnetic periods is described. The method uses solar situations along the CM with the key role of filaments, giving indirect evidence of types of directly unobservable coronal structures above them. The time lag, not to be interpreted in terms of propagation speed, between the CM activity and the commencement of the geomagnetic response is about one to two days. Solar phenomena serve as indicators within approximately 10 deg of the CM and up to the zone of high latitude filaments.

  19. Linking geomagnetic activity and polar surface air temperature variability

    NASA Astrophysics Data System (ADS)

    Seppala, Annika

    ERA-40 and ECMWF operational surface level air temperature (SAT) data sets from 1957 to 2006 were used to examine polar temperature variations during years with different levels of geomagnetic activity, as defined by the Ap index. Previous modelling work has suggested that NOx produced at high latitudes by energetic particle precipitation can eventually lead to detectable changes in polar SATs. We find that during winter months, ERA-40 and ECMWF polar SATs in years with high Ap index are different than in years with low Ap index; the differences are statistically significant at the 2-sigma level and range up to about ±4.5 K, de-pending on location. The temperature differences are larger when years with wintertime Sudden Stratospheric Warmings are excluded. Solar irradiance variations were taken into account in the analysis. Although using the re-analysis and operational data sets it was not possible to conclusively show that the polar SAT patterns are physically linked by geomagnetic activity, we conclude that geomagnetic activity likely plays a role in modulating polar wintertime surface air temperature patterns. The SAT results were tested against variation in the Quasi Biennial Oscillation (QBO), the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode n (SAM). The results suggested that these were not driving the observed polar SAT variability. However, significant uncertainty is introduced by the Northern Annular Mode (NAM) and we could not robustly exclude a chance linkage between sea surface temperature (SST) variability and geomagnetic activity. Examining the physical link between geomagnetic activity and polar surface temperature variability patterns using atmospheric models is an ongoing task.

  20. Long-term monthly statistics of the mid-latitude ionospheric E-layer peak electron density in the Northern geographic hemisphere during geomagnetically quiet and steadily low solar activity conditions

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    2016-07-01

    Long-term hourly values of the ionospheric E-layer peak electron density, NmE, measured during the time period of 1957-2014 by 4 mid-latitude ionosondes (Wallops Island, Boulder, de l'Ebre, and Rome) in the Northern geographic hemisphere were processed to select periods of geomagnetically quiet and low solar activity conditions to calculate several descriptive statistics of NmE close to noon for each month in a year, including the mathematical expectation of NmE, the standard deviations of NmE from the mathematically expected NmE, and the NmE variation coefficient. The month-to-month variability of these descriptors allowed us to identify months of a year when they reach their extremes (maxima, minima). We found that the most probable NmE cannot be considered as the best statistical parameter among the most probable NmE and the mathematically expected NmE in statistical studies of month-to-month variations of NmE. Depending on a choice of an ionosonde and a month, the calculated NmE variation coefficient changes from 5 to 12 %.

  1. Heliospheric and Geomagnetic Modulation of Galactic Cosmic Ray under Quiet and disturbed interplanetary conditions during Solar cycle 20-23.

    NASA Astrophysics Data System (ADS)

    Kalu, F. D.

    2015-12-01

    The modulation of galactic cosmic rays (GCR) within the heliosphere leads to a reduction in the GCR count rates during period of high solar activity and conversely. Data from three geomagnetic observatories and three Neutron monitors (in close proximity to the geomagnetic stations) have been studied. The monthly residuals of the geomagnetic field components with respect to quiet time conditions from these three stations have been computed and compared with the cosmic ray count rates. The modulations of the GCR during quiet and disturbed interplanetary conditions have been investigated with a view to better understand the role of the global merged interaction regions and coronal mass ejections to the GCR modulation. From first-order partial correlation, we found that removing the influence of the total IMF-B, (especially during quiet conditions), and the influence of SW dynamic pressure (during disturbed conditions) generally enhances the correlation of the residual geomagnetic field with the GCR significantly. The influence of the more subtle parameters like speed, Bz component and proton density were masked by these dominant parameters. Results from this work are important for the modeling of long term GCR variability.

  2. Heliospheric and geomagnetic modulation of galactic cosmic rays under quiet and disturbed interplanetary conditions during solar cycles 20-23

    NASA Astrophysics Data System (ADS)

    Chukwudi Okpala, Kingsley

    2015-08-01

    The modulation of galactic cosmic rays (GCR) within the heliosphere leads to a reduction in the GCR count rates during period of high solar activity and conversely. Data from three geomagnetic observatories and three Neutron monitors (in close proximity to the geomagnetic stations) have been studied. The monthly residuals of the geomagnetic field components with respect to quiet time conditions from these three stations have been computed and compared with the cosmic ray count rates. The modulations of the GCR during quiet and disturbed interplanetary conditions have been investigated with a view to better understand the role of the global merged interaction regions and intense magnetic fields to the GCR modulation. From first-order partial correlation, we found that removing the influence of the total IMF-B, (especially during quiet conditions) and the influence of SW dynamic pressure (during disturbed conditions) generally enhances the correlation of the residual geomagnetic field with the GCR significantly. The influence of the more subtle parameters like speed, Bz component and proton density were masked by these dominant parameters. Results from this work are important for the modeling of long term GCR variability.

  3. ISEE 3 observations during the CDAW 8 intervals - Case studies of the distant geomagnetic tail covering a wide range of geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Slavin, J. A.; Owen, C. J.; Cowley, S. W. H.; Galvin, A. B.; Sanderson, T. R.; Scholer, M.

    1989-01-01

    Observations made by the ISEE 3 spacecraft in the distant geomagnetic tail during the eight CDAW 8 intervals are discussed, along with their relation to concurrent geomagnetic activity. This extensive multiinstrument case study of distant tail data covers a wide range of geomagnetic conditions from extended intervals of magnetic quiet with isolated substorms to prolonged periods of intense disturbance. Plasmoids are observed in the distant tail following disturbance enhancements, the time of their appearance being generally consistent with disconnection from the near-earth region at the time of the enhancement. Their structure is entirely consistent with the neutral line model. However, not all enhancements in geomagnetic activity result in the observation of plasmoids. In particular, the CDAW 8 data suggest that, during extended intervals of strong activity, a continuous neutral line may reside in the near-earth tail and some disturbance enhancements may then relate to an increase in the reconnection rate at a preexisting neutral line, rather than to new neutral line and plasmoid formation.

  4. Spring-fall asymmetry of substorm strength, geomagnetic activity and solar wind: Implications for semiannual variation and solar hemispheric asymmetry

    USGS Publications Warehouse

    Mursula, K.; Tanskanen, E.; Love, J.J.

    2011-01-01

    We study the seasonal variation of substorms, geomagnetic activity and their solar wind drivers in 1993-2008. The number of substorms and substorm mean duration depict an annual variation with maxima in Winter and Summer, respectively, reflecting the annual change of the local ionosphere. In contradiction, substorm mean amplitude, substorm total efficiency and global geomagnetic activity show a dominant annual variation, with equinoctial maxima alternating between Spring in solar cycle 22 and Fall in cycle 23. The largest annual variations were found in 1994 and 2003, in the declining phase of the two cycles when high-speed streams dominate the solar wind. A similar, large annual variation is found in the solar wind driver of substorms and geomagnetic activity, which implies that the annual variation of substorm strength, substorm efficiency and geomagnetic activity is not due to ionospheric conditions but to a hemispherically asymmetric distribution of solar wind which varies from one cycle to another. Our results imply that the overall semiannual variation in global geomagnetic activity has been seriously overestimated, and is largely an artifact of the dominant annual variation with maxima alternating between Spring and Fall. The results also suggest an intimate connection between the asymmetry of solar magnetic fields and some of the largest geomagnetic disturbances, offering interesting new pathways for forecasting disturbances with a longer lead time to the future. Copyright ?? 2011 by the American Geophysical Union.

  5. Spring-fall asymmetry of substorm strength, geomagnetic activity and solar wind: Implications for semiannual variation and solar hemispheric asymmetry

    USGS Publications Warehouse

    Marsula, K.; Tanskanen, E.; Love, J.J.

    2011-01-01

    We study the seasonal variation of substorms, geomagnetic activity and their solar wind drivers in 1993–2008. The number of substorms and substorm mean duration depict an annual variation with maxima in Winter and Summer, respectively, reflecting the annual change of the local ionosphere. In contradiction, substorm mean amplitude, substorm total efficiency and global geomagnetic activity show a dominant annual variation, with equinoctial maxima alternating between Spring in solar cycle 22 and Fall in cycle 23. The largest annual variations were found in 1994 and 2003, in the declining phase of the two cycles when high-speed streams dominate the solar wind. A similar, large annual variation is found in the solar wind driver of substorms and geomagnetic activity, which implies that the annual variation of substorm strength, substorm efficiency and geomagnetic activity is not due to ionospheric conditions but to a hemispherically asymmetric distribution of solar wind which varies from one cycle to another. Our results imply that the overall semiannual variation in global geomagnetic activity has been seriously overestimated, and is largely an artifact of the dominant annual variation with maxima alternating between Spring and Fall. The results also suggest an intimate connection between the asymmetry of solar magnetic fields and some of the largest geomagnetic disturbances, offering interesting new pathways for forecasting disturbances with a longer lead time to the future.

  6. Effects of geomagnetic activity variations on the physiological and psychological state of functionally healthy humans: Some results of Azerbaijani studies

    NASA Astrophysics Data System (ADS)

    Babayev, Elchin S.; Allahverdiyeva, Aysel A.

    There are collaborative and cross-disciplinary space weather studies in the Azerbaijan National Academy of Sciences conducted with purposes of revealing possible effects of solar, geomagnetic and cosmic ray variability on certain technological, biological and ecological systems. This paper describes some results of the experimental studies of influence of the periodical and aperiodical changes of geomagnetic activity upon human brain, human health and psycho-emotional state. It also covers the conclusions of studies on influence of violent solar events and severe geomagnetic storms of the solar cycle 23 on the mentioned systems in middle-latitude location. It is experimentally established that weak and moderate geomagnetic storms do not cause significant changes in the brain's bioelectrical activity and exert only stimulating influence while severe disturbances of geomagnetic conditions cause negative influence, seriously disintegrate brain's functionality, activate braking processes and amplify the negative emotional background of an individual. It is concluded that geomagnetic disturbances affect mainly emotional and vegetative spheres of human beings while characteristics reflecting personality properties do not undergo significant changes.

  7. Active experiments in the ionosphere and geomagnetic field variations

    NASA Astrophysics Data System (ADS)

    Sivokon, V. P.; Cherneva, N. V.; Khomutov, S. Y.; Serovetnikov, A. S.

    2014-11-01

    Variations of ionospheric-magnetospheric relation energy, as one of the possible outer climatology factors, may be traced on the basis of analysis of natural geophysical phenomena such as ionosphere artificial radio radiation and magnetic storms. Experiments on active impact on the ionosphere have been carried out for quite a long time in Russia as well. The most modern heating stand is located in Alaska; it has been used within the HAARP Program. The possibility of this stand to affect geophysical fields, in particular, the geomagnetic field is of interest.

  8. Modelling total electron content during geomagnetic storm conditions using empirical orthogonal functions and neural networks

    NASA Astrophysics Data System (ADS)

    Uwamahoro, Jean Claude; Habarulema, John Bosco

    2015-12-01

    It has been shown in ionospheric research that modelling total electron content (TEC) during storm conditions is a big challenge. In this study, TEC modelling was performed over Sutherland (32.38°S, 20.81°E, 41.09°S geomagnetic), South Africa, during storm conditions, using a combination of empirical orthogonal function (EOF) and regression analyses techniques. The neural network (NN) technique was also applied to the same TEC data set, and its output was compared with TEC modeled using the EOF model. TEC was derived from GPS observations, and a geomagnetic storm was defined for Dst≤-50 nT. The hour of the day and the day number of the year, F10.7p and A indices, were chosen as inputs for the modeling techniques to take into account diurnal and seasonal variation of TEC, solar, and geomagnetic activities, respectively. Both EOF and NN models were developed using GPS TEC data for storm days counted from 1999 to 2013 and tested on different storms. For interpolation, the EOF and NN models were validated on storms that occurred during high and low solar activity periods (storms of 2000 and 2006), while for extrapolation the validation was done for the storms of 2014 and 2015, identified based on the provisional Dst index data. A comparison of the modeled TEC with the observed TEC showed that both EOF and NN models perform well for storms with nonsignificant ionospheric TEC response and storms that occurred during period of low solar activity. For storms with significant TEC response, TEC magnitude is well captured during the nighttime and early morning, but short-term features, TEC enhancement, and depression are not sufficiently captured by the models. Statistically, the NN model performs 12.79% better than the EOF model on average, over all storm periods considered. Furthermore, it has been shown that the EOF and NN models developed for a specific station can be used to estimate TEC over other locations within a latitudinal and longitudinal coverage of 8.7

  9. Origins of the semiannual variation of geomagnetic activity in 1954 and 1996

    NASA Astrophysics Data System (ADS)

    Cliver, E.; Svalgaard, L.; Ling, A.

    2004-01-01

    . We investigate the cause of the unusually strong semiannual variation of geomagnetic activity observed in the solar minimum years of 1954 and 1996. For 1996 we separate the contributions of the three classical modulation mechanisms (axial, equinoctial, and Russell-McPherron) to the six-month wave in the index and find that all three contribute about equally. This is in contrast to the longer run of geomagnetic activity (1868-1998) over which the equinoctial effect accounts for 70% of the semiannual variation. For both 1954 and 1996, we show that the Russell-McPherron effect was enhanced by the Rosenberg-Coleman effect (an axial polarity effect) which increased the amount of the negative (toward Sun) [positive (away from Sun)] polarity field observed during the first [second] half of the year; such fields yield a southward component in GSM coordinates. Because this favourable condition occurs only for alternate solar cycles, the marked semiannual variation in 1954 and 1996 is a manifestation of the 22-year cycle of geomagnetic activity. The 11-year evolution of the heliospheric current sheet (HCS) also contributes to the strong six-month wave during these years. At solar minimum, the streamer belt at the base of the HCS is located near the solar equator, permitting easier access to high speed streams from polar coronal holes when the Earth is at its highest heliographic latitudes in March and September. Such an axial variation in solar wind speed was observed for 1996 and is inferred for 1954.

  10. Geomagnetic responses to the solar wind and the solar activity

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1975-01-01

    Following some historical notes, the formation of the magnetosphere and the magnetospheric tail is discussed. The importance of electric fields is stressed and the magnetospheric convection of plasma and magnetic field lines under the influence of large-scale magnetospheric electric fields is outlined. Ionospheric electric fields and currents are intimately related to electric fields and currents in the magnetosphere and the strong coupling between the two regions is discussed. The energy input of the solar wind to the magnetosphere and upper atmosphere is discussed in terms of the reconnection model where interplanetary magnetic field lines merge or connect with the terrestrial field on the sunward side of the magnetosphere. The merged field lines are then stretched behind earth to form the magnetotail so that kinetic energy from the solar wind is converted into magnetic energy in the field lines in the tail. Localized collapses of the crosstail current, which is driven by the large-scale dawn/dusk electric field in the magnetosphere, divert part of this current along geomagnetic field lines to the ionosphere, causing substorms with auroral activity and magnetic disturbances. The collapses also inject plasma into the radiation belts and build up a ring current. Frequent collapses in rapid succession constitute the geomagnetic storm.

  11. Prediction of Geomagnetic Activity and Key Parameters in High-Latitude Ionosphere-Basic Elements

    NASA Technical Reports Server (NTRS)

    Lyatsky, W.; Khazanov, G. V.

    2007-01-01

    Prediction of geomagnetic activity and related events in the Earth's magnetosphere and ionosphere is an important task of the Space Weather program. Prediction reliability is dependent on the prediction method and elements included in the prediction scheme. Two main elements are a suitable geomagnetic activity index and coupling function -- the combination of solar wind parameters providing the best correlation between upstream solar wind data and geomagnetic activity. The appropriate choice of these two elements is imperative for any reliable prediction model. The purpose of this work was to elaborate on these two elements -- the appropriate geomagnetic activity index and the coupling function -- and investigate the opportunity to improve the reliability of the prediction of geomagnetic activity and other events in the Earth's magnetosphere. The new polar magnetic index of geomagnetic activity and the new version of the coupling function lead to a significant increase in the reliability of predicting the geomagnetic activity and some key parameters, such as cross-polar cap voltage and total Joule heating in high-latitude ionosphere, which play a very important role in the development of geomagnetic and other activity in the Earth s magnetosphere, and are widely used as key input parameters in modeling magnetospheric, ionospheric, and thermospheric processes.

  12. The persistence of equatorial spread F - an analysis on seasonal, solar activity and geomagnetic activity aspects

    NASA Astrophysics Data System (ADS)

    Sreeja, V.; Devasia, C. V.; Ravindran, Sudha; Sridharan, R.

    2009-02-01

    The persistence (duration) of Equatorial Spread F (ESF), which has significant impact on communication systems, is addressed. Its behavior during different seasons and geomagnetic activity levels under the solar maximum (2001) and minimum (2006) conditions, is reported using the data from the magnetic equatorial location of Trivandrum (8.5° N; 77° E; dip 0.5° N) in India. The study reveals that the persistence of the irregularities can be estimated to a reasonable extent by knowing the post sunset F region vertical drift velocity (Vz) and the magnetic activity index Kp. Any sort of advance information on the possible persistence of the ionospheric irregularities responsible for ESF is important for understanding the scintillation morphology, and the results which form the first step in this direction are presented and discussed.

  13. Cosmic rays, conditions in interplanetary space and geomagnetic variations during solar cycles 19-24

    NASA Astrophysics Data System (ADS)

    Biktash, Lilia

    2016-07-01

    We have studied conditions in interplanetary space, which can have an influence on galactic and solar cosmic rays (CRs). In this connection the solar wind and interplanetary magnetic field parameters and CRs variations have been compared with geomagnetic activity represented by the equatorial Dst and Kp indices beginning from 1955 to the end 2015. The indices are in common practice in the solar wind-magnetosphere-ionosphere interaction studies and they are the final product of this interaction. The important drivers in interplanetary medium which have effect on cosmic rays as CMEs (coronal mass ejections) and CIRs (corotating interaction regions) undergo very strong changes during their propagation to the Earth. Correlation of sunspot numbers and long-term variations of cosmic rays do not adequately reflect peculiarities concerned with the solar wind arrival to 1 AU also. Moreover records of in situ space measurements of the IMF and most other indicators of solar activity cover only a few decades and have a lot of gaps for calculations of long-term variations. Because of this, in such investigations, the geomagnetic indices have some inestimable advantage as continuous series other the solar wind measurements. We have compared the yearly average variations of the indices and of the solar wind parameters with cosmic ray data from Moscow, Climax, Halekala and Oulu neutron monitors during the 20-24 solar cycles. During the descending phases of the solar cycles the long-lasting solar wind high speed streams occurred frequently and were the primary contributors to the recurrent Dst variations and had effects on cosmic rays variations. We show that long-term Dst and Kp variations in these solar cycles were correlated with cosmic ray count rates and can be used for prediction of CR variations. Climate change in connection with evolution of CRs variations is discussed.

  14. A Geomagnetic Precursor Technique for Predicting the Solar Activity Cycle

    NASA Astrophysics Data System (ADS)

    Sobel, E. I.; Rabin, D. M.

    2015-12-01

    The Western hemisphere has been recording sunspot numbers since Galileo discovered sunspots in the early 17th century, and the roughly 11-year solar cycle has been recognized since the 19th century. However, predicting the strength of any particular cycle remains a relatively imprecise task. This project's aim was to update and improve a forecasting technique based on geomagnetic precursors of future solar activity The model is a refinement of R. J. Thompson's 1993 paper that relates the number of geomagnetically disturbed days, as defined by the aa and Ap indices, to the sum of the sunspot number in the current and the previous cycle, Rn + Rn-1.[1] The method exploits the fact that two cycles coexist for some period on the Sun near solar minimum and therefore that the number of sunspots and disturbed days during the declining phase of one cycle gives an indication of the following cycle's strength. We wrote and updated IDL software procedures to define disturbed days with varying threshold values and graphed Rn + Rn-1 against them. The aa threshold was derived from the Ap threshold. After comparing the graphs for Ap values from 20 to 50, an Ap threshold of 30 and the corresponding aa threshold of 44 were chosen as yielding the best correlation. Confidence regions were computed to provide a quantitative uncertainty on future predictions. The 80% confidence region gives a range of ±40 in sunspot number. [1] Thompson, R. J. (1993). A technique for predicting the amplitude of the solar cycle. Solar Physics, 148, 2, 383-388.

  15. Lagged association between geomagnetic activity and diminished nocturnal pain thresholds in mice.

    PubMed

    Galic, M A; Persinger, M A

    2007-10-01

    A wide variety of behaviors in several species has been statistically associated with the natural variations in geomagnetism. To examine whether changes in geomagnetic activity are associated with pain thresholds, adult mice were exposed to a hotplate paradigm once weekly for 52 weeks during the dark cycle. Planetary A index values from the previous 6 days of a given hotplate session were correlated with the mean response latency for subjects to the thermal stimulus. We found that hotplate latency was significantly (P < 0.05) and inversely correlated (rho = -0.25) with the daily geomagnetic intensity 3 days prior to testing. Therefore, if the geomagnetic activity was greater 3 days before a given hotplate trial, subjects tended to exhibit shorter response latencies, suggesting lower pain thresholds or less analgesia. These results are supported by related experimental findings and suggest that natural variations in geomagnetic intensity may influence nociceptive behaviors in mice. PMID:17657732

  16. Variations of terrestrial geomagnetic activity correlated to M6+ global seismic activity

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2013-04-01

    From the surface of the Sun, as a result of a solar flare, are expelled a coronal mass (CME or Coronal Mass Ejection) that can be observed from the Earth through a coronagraph in white light. This ejected material can be compared to an electrically charged cloud (plasma) mainly composed of electrons, protons and other small quantities of heavier elements such as helium, oxygen and iron that run radially from the Sun along the lines of the solar magnetic field and pushing into interplanetary space. Sometimes the CME able to reach the Earth causing major disruptions of its magnetosphere: mashed in the region illuminated by the Sun and expanding in the region not illuminated. This interaction creates extensive disruption of the Earth's geomagnetic field that can be detected by a radio receiver tuned to the ELF band (Extreme Low Frequency 0-30 Hz). The Radio Emissions Project (scientific research project founded in February 2009 by Gabriele Cataldi and Daniele Cataldi), analyzing the change in the Earth's geomagnetic field through an induction magnetometer tuned between 0.001 and 5 Hz (bandwidth in which possible to observe the geomagnetic pulsations) was able to detect the existence of a close relationship between this geomagnetic perturbations and the global seismic activity M6+. During the arrival of the CME on Earth, in the Earth's geomagnetic field are generated sudden and intensive emissions that have a bandwidth including between 0 and 15 Hz, an average duration of 2-8 hours, that preceding of 0-12 hours M6+ earthquakes. Between 1 January 2012 and 31 December 2012, all M6+ earthquakes recorded on a global scale were preceded by this type of signals which, due to their characteristics, have been called "Seismic Geomagnetic Precursors" (S.G.P.). The main feature of Seismic Geomagnetic Precursors is represented by the close relationship that they have with the solar activity. In fact, because the S.G.P. are geomagnetic emissions, their temporal modulation depends

  17. Effects of geomagnetic activity and atmospheric power variations on quantitative measures of brain activity: Replication of the Azerbaijani studies

    NASA Astrophysics Data System (ADS)

    Mulligan, Bryce P.; Hunter, Mathew D.; Persinger, Michael A.

    2010-04-01

    This study replicates and extends the observations by Babayev and Allahveriyeva that changes in right hemispheric electroencephalographic activity are correlated with increases in geomagnetic activity. During the geomagnetically quiet interface between solar cycle 23 and 24 quantitative electroencephalographic (QEEG) measurements were completed for normal young adults in three separate experiments involving about 120 samples over 1.5 years. The most consistent, moderate strength correlations occurred for the changes in power within the gamma and theta ranges over the right frontal lobe. Real-time measures of atmospheric power obtained from polar orbiting satellites showed similar effects. The preferential involvement of the right frontal lobe and the regions subject to its inhibition with environmental energetic changes are consistent with the behavioural correlations historically associated with these conditions. They include increased incidence of emotional lability, erroneous reconstruction of experiences, social confrontations, and unusual perceptions.

  18. Geomagnetic Activity Forecasting Model based on SW-M-I coupling

    NASA Astrophysics Data System (ADS)

    Nagatsuma, Tsutomu; Kunitake, Manabu

    Prediction of geomagnetic activity is one of the fundamental issues of space weather forecast. We are developing geomagnetic activity forecasting model based on the solar wind -magneto-sphere -ionosphere (SW-M-I) coupling. The key point of our forecasting model is ionosphereic conductivity dependence of the coupling function. We have found that the efficiency of SW-M-I coupling is not constant but has a dependence of ionospheric conductivity within the polar cap. Therefore, operational forecasting model of geomagnetic activity should take into account these variations and dependence. Our model can explain the diurnal and semiannual and solar cycle variations of geomagnetic activity from solar wind parameter and F10.7 index. We also examine the possibility of using inner heliospheric solar wind data such as STEREO data for a few days advance of geomagnetic activity forecast. Based on the comparison between ACE and STEREO data, we have found that the solar wind velocity can be predicted from the STEREO data well, but the Bz component of interplanetary magnetic field (IMF) is difficult to predict rather than the magnitude of IMF. This suggests that the probabilistic approach is needed for the mid-term geomagnetic forecast. We will introduce the future direction of our geomagnetic activity forecasting model in our talk.

  19. Solar and geomagnetic activity, extremely low frequency magnetic and electric fields and human health at the Earth's surface

    NASA Astrophysics Data System (ADS)

    Palmer, S. J.; Rycroft, M. J.; Cermack, M.

    2006-09-01

    The possibility that conditions on the Sun and in the Earth’s magnetosphere can affect human health at the Earth’s surface has been debated for many decades. This work reviews the research undertaken in the field of heliobiology, focusing on the effect of variations of geomagnetic activity on human cardiovascular health. Data from previous research are analysed for their statistical significance, resulting in support for some studies and the undermining of others. Three conclusions are that geomagnetic effects are more pronounced at higher magnetic latitudes, that extremely high as well as extremely low values of geomagnetic activity seem to have adverse health effects and that a subset of the population (10-15%) is predisposed to adverse health due to geomagnetic variations. The reported health effects of anthropogenic sources of electric and magnetic fields are also briefly discussed, as research performed in this area could help to explain the results from studies into natural electric and magnetic field interactions with the human body. Possible mechanisms by which variations in solar and geophysical parameters could affect human health are discussed and the most likely candidates investigated further. Direct effects of natural ELF electric and magnetic fields appear implausible; a mechanism involving some form of resonant absorption is more likely. The idea that the Schumann resonance signals could be the global environmental signal absorbed by the human body, thereby linking geomagnetic activity and human health is investigated. Suppression of melatonin secreted by the pineal gland, possibly via desynchronised biological rhythms, appears to be a promising contender linking geomagnetic activity and human health. There are indications that calcium ions in cells could play a role in one or more mechanisms. It is found to be unlikely that a single mechanism can explain all of the reported phenomena.

  20. Investigation of Fast and Slow CMEs Effect on Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Donmez, Burcin; Kilcik, Ali

    2016-07-01

    Here we investigate the relationship between the fast (v>800 km/s) and slow (v<400 km/s) coronal mass ejections (CMEs) and geomagnetic Ap and Dst indices during the last two solar cycles (cycle 23 and 24). In result of our analysis we found following results 1) Fast CMEs show much better relationship with geomagnetic Ap and Dst indices compared to slow ones, 2) Similar to geomagnetic indices, the number of fast CMEs decreased seriously during solar cycle 24th, while the number of slow CMEs are almost the same during the investigated whole time interval (1996 through 2016).

  1. Effect of enhanced geomagnetic activity on hypothermia and mortality in rats

    NASA Astrophysics Data System (ADS)

    Bureau, Y. R. J.; Persinger, M. A.; Parker, G. H.

    1996-12-01

    The hypothesis was investigated that variability in the severity of limbic seizure-induced hypothermia in rats was affected by ambient geomagnetic activity. Data were obtained in support of this hypothesis. The depth of the hypothermia was significantly ( P < 0.001) reduced if the ambient geomagnetic activity exceeded 35 nT to 40 nT. Mortality during the subsequent 5 days was increased when the geomagnetic activity was > 20 nT. The magnitude of the effect was comparable to the difference between exposure to light or to darkness during the 20 h after the induction of limbic seizures.

  2. Solar activity and human health at middle and low geomagnetic latitudes in Central America

    NASA Astrophysics Data System (ADS)

    Mendoza, Blanca; Sánchez de La Peña, Salvador

    2010-08-01

    The study of the possible effect of solar variability on living organisms is one of the most controversial issues of present day science. It has been firstly and mainly carried on high latitudes, while at middle and low latitudes this study is rare. In the present review we focused on the work developed at middle and low geomagnetic latitudes of America. At these geomagnetic latitudes the groups consistently dedicated to this issue are mainly two, one in Cuba and the other in Mexico. The Cuban and Mexican studies show that at such latitudes there are biological consequences to the solar/geomagnetic activity, coinciding in four points: (1) the male population behave differently from the female population, (2) the most vulnerable age group to geomagnetic perturbations is that of ⩾65 years old, (3) there is a tendency for myocardial infarctions (death or occurrence) to increase one day after a geomagnetic Ap index large value or during the day of the associated Forbush decrease, and (4) the myocardial infarctions (death or occurrence) increase as the geomagnetic perturbation increases. Additionally, the Cuban group found seasonal periodicities from their data, and also that increases of female myocardial infarctions occurred before and after the day of the geomagnetic disturbance. The Mexican group found that the male sex is more vulnerable to geomagnetic perturbations and that the myocardial infarction deaths present the conspicuous cycle of ˜7 days.

  3. Towards more reliable long-term indices of geomagnetic activity: correcting a new inhomogeneity problem in early geomagnetic data

    NASA Astrophysics Data System (ADS)

    Holappa, Lauri; Mursula, Kalevi

    2016-07-01

    For the time before the space era our knowledge of the centennial evolution of solar wind (SW) and interplanetary magnetic field (IMF) is based on proxies derived from geomagnetic indices. The reliability of these proxies is dependent on the homogeneity of magnetic field data. In this paper we study the interhourly (IHV) and interdiurnal (IDV_{1d}) variability indices calculated from the data of two British observatories, Eskdalemuir and Lerwick, and compare them to the corresponding indices of the German Niemegk observatory. We find an excess of about 14 ± 4% (5.8 ± 2%) and 27 ± 10% (15 ± 6%) in the IHV (IDV_{1d}) in the indices of Eskdalemuir and Lerwick in 1935-1969. The timing of this excess accurately coincides with instrument changes made in these observatories, strongly supporting the interpretation that the excess is indeed caused by instrument related inhomogeneities in the data of Eskdalemuir and Lerwick. We show that the detected excess notably modifies the long-term trend of geomagnetic activity and the centennial evolution of IMF strength and solar wind speed estimated using these indices. We note that the detected inhomogeneity problem may not be limited to the data of the two studied observatories, but may be quite common to long series of geomagnetic measurements. These results question the reliability of the present measures of the centennial change in solar wind speed and IMF.

  4. Study of Fractal Features of Geomagnetic Activity Through an MHD Shell Model

    NASA Astrophysics Data System (ADS)

    Dominguez, M.; Nigro, G.; Munoz, V.; Carbone, V.

    2013-12-01

    Studies on complexity have been of great interest in plasma physics, because they provide new insights and reveal possible universalities on issues such as geomagnetic activity, turbulence in laboratory plasmas, physics of the solar wind, etc. [1, 2]. In particular, various studies have discussed the relationship between the fractal dimension, as a measure of complexity, and physical processes in magnetized plasmas such as the Sun's surface, the solar wind and the Earth's magnetosphere, including the possibility of forecasting geomagnetic activity [3, 4, 5]. Shell models are low dimensional dynamical models describing the main statistical properties of magnetohydrodynamic (MHD) turbulence [6]. These models allow us to describe extreme parameter conditions hence reaching very high Reynolds (Re) numbers. In this work a MHD shell model is used to describe the dissipative events which are taking place in the Earth's magnetosphere and causing geomagnetic storms. The box-counting fractal dimension (D) [7] is calculated for the time series of the magnetic energy dissipation rate obtained in this MHD shell model. We analyze the correlation between D and the energy dissipation rate in order to make a comparison with the same analysis made on the geomagnetic data. We show that, depending on the values of the viscosity and the diffusivity, the fractal dimension and the occurrence of bursts exhibit correlations similar as those observed in geomagnetic and solar data, [8] suggesting that the latter parameters could play a fundamental role in these processes. References [1] R. O. Dendy, S. C. Chapman, and M. Paczuski, Plasma Phys. Controlled Fusion 49, A95 (2007). [2] T. Chang and C. C. Wu, Phys. Rev. E 77, 045401 (2008). [3] R. T. J. McAteer, P. T. Gallagher, and J. Ireland, Astrophys. J. 631, 628 (2005). [4] V. M. Uritsky, A. J. Klimas, and D. Vassiliadis, Adv. Space Res. 37, 539 (2006). [5] S. C. Chapman, B. Hnat, and K. Kiyani, Nonlinear Proc. Geophys. 15, 445 (2008). [6] G

  5. Geomagnetic activity influences the melatonin secretion at latitude 70 degrees N.

    PubMed

    Weydahl, A; Sothern, R B; Cornélissen, G; Wetterberg, L

    2001-01-01

    Factors other than light may affect variations in melatonin, including disturbances in the geomagnetic field. Such a possibility was tested in Alta, Norway, located at latitude 70 degrees N, where the aurora borealis is a result of large changes in the horizontal component (H) of the geomagnetic field. Geomagnetic disturbances are felt more strongly closer to the pole than at lower latitudes. Also noteworthy in Alta is the fact that the sun does not rise above the horizon for several weeks during the winter. To examine whether changes in geomagnetic activity influence the secretion of melatonin, saliva was collected from 25 healthy subjects in Alta several times during the day-night and at different times of the year. Single cosinor analyses yielded individual estimates of.the circadian amplitude and MESOR of melatonin. A 3-hour mean value for the local geomagnetic activity index, K, was used for approximately the same 24-hour span. A circadian rhythm was found to characterize both melatonin and K, the peak in K (23:24) preceding that of melatonin (06:08). During the span of investigation, a circannual variation also characterized both variables. Correlation analyses suggest that changes in geomagnetic activity had to be of a certain magnitude to affect the circadian amplitude of melatonin. If large enough (> 80 nT/3 h), changes in geomagnetic activity also significantly decreased salivary melatonin concentration. PMID:11774869

  6. Synchronization of heart rate indices of human and Pc5 pulsations in the geomagnetic quiet conditions

    NASA Astrophysics Data System (ADS)

    Zenchenko, Tatiana

    Geomagnetic pulsations with duration of the period over 150 seconds (Pc5-6) are present in the magnetosphere almost constantly. Unlike other types of geomagnetic pulsations, they are characterized by high amplitudes reaching in auroral latitudes 30-100 nT, and even 300 - 600 nT in time of significant geomagnetic disturbances [1]. To date, it is generally accepted that the classic morning and afternoon Pc5 pulsations in the magnetosphere are toroidal Alfven resonance vibrations of the geomagnetic field lines [2, 3]. It was revealed that the basic oscillation periods, presented in heart rate variability of healthy subjects, in conditions of rest, at each time point substantially coincide with the periods of oscillation of the X-vector components of the geomagnetic field in the frequency range of Pc5-6 pulsations. Synchronization effect was observed in approximately 60% of cases [4]. The above statement is based on the results of more than 100 experiments (recording time from 60 to 200 min), conducted in the period 2011-2013 in various research groups [4]. In total, 37 volunteers in the age range 18-65 yrs took part in the experiments. Experiments were performed in Pushchino and Khimki (Moscow region), Arkhangelsk, Tomsk, Sofia (Bulgaria), as well as at the station Starorusskaya (Leningrad region). The geomagnetic data were obtained from INTERMAGNET network (http://ottawa.intermagnet.org/Welcom_e.php). From a biophysical point of view, the observed effects of timing fluctuations of heart rate of healthy subjects with the oscillations of the magnetic induction vector of the GMF could be an effective tool for solving one of the most actual problems in heliobiophysics, namely the identification of specific physiological mechanisms of biosystems response to low-intensity variations external factors. 1. Pilipenko V.A., Kleimenova N.G., Kozyreva O.V., Yumoto K., Bitterly G. Geomagnetism and aeronomy, 1997, V. 37, №.3, P. 64-76 2. Chen L. and Hasegawa A. J.Geophys. Res

  7. Geomagnetic activity associated with Earth passage of interplanetary shock disturbances and coronal mass ejections

    SciTech Connect

    Gosling, J.T.; McComas, D.J.; Phillips, J.L.; Bame, S.J. )

    1991-05-01

    Previous work indicates that virtually all transient shock wave disturbances in the solar wind are driven by fast coronal mass ejection events (CMEs). Using a recently appreciated capability for distinguishing CMEs in solar wind data in the form of counterstreaming solar wind electron events, this paper explores the overall effectiveness of shock wave disturbances and CMEs in general in stimulating geomagnetic activity. The study is confined to the interval from mid-August 1978 through mid-October 1982, spanning the last solar activity maximum, when ISEE 3 was in orbit about the L1 Lagrange point 220 R{sub e} upstream from Earth. The authors find that all but one of the 37 largest geomagnetic storms in that era were associated with Earth passage of CMEs and/or shock disturbances, with the large majority of these storms being associated with interplanetary events where Earth encountered both a shock and the CME driving the shock (shock/CME events). Although CMEs and/or shock disturbances were increasingly the cause of geomagnetic activity as the level of geomagnetic activity increased, many smaller geomagnetic disturbances were unrelated to these events. Further, approximately half of all CMEs and half of all shock disturbances encountered by Earth did not produce any substantial geomagnetic activity as measured by the planetary geomagnetic index Kp. The geomagnetic effectiveness of Earth directed CMEs and shock wave disturbances was directly related to the flow speed, the magnetic field magnitude, and the strength of the southward (GSM) field component associated with the events. The initial speed of a CME close to the Sun appears to be the most crucial factor in determining if an earthward directed event will be effective in exciting a large geomagnetic disturbance.

  8. Improvements in short-term forecasting of geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Bala, Ramkumar; Reiff, Patricia

    2012-06-01

    We have improved our space weather forecasting algorithms to now predict Dst and AE in addition to Kp for up to 6 h of forecast times. These predictions can be accessed in real time at http://mms.rice.edu/realtime/forecast.html. In addition, in the event of an ongoing or imminent activity, e-mail "alerts" based on key discriminator levels have been going out to our subscribers since October 2003. The neural network-based algorithms utilize ACE data to generate full 1, 3, and 6 h ahead predictions of these indices from the Boyle index, an empirical approximation that estimates the Earth's polar cap potential using solar wind parameters. Our models yield correlation coefficients of over 0.88, 0.86, and 0.83 for 1 h predictions of Kp, Dst, and AE, respectively, and 0.86, 0.84, and 0.80 when predicting the same but 3 h ahead. Our 6 h ahead predictions, however, have slightly higher uncertainties. Furthermore, the paper also tests other solar wind functions—the Newell driver, the Borovsky control function, and adding solar wind pressure term to the Boyle index—for their ability to predict geomagnetic activity.

  9. Geomagnetic activity during the previous day is correlated with increased consumption of sucrose during subsequent days: is increased geomagnetic activity aversive?

    PubMed

    Galic, M A; Persinger, M A

    2004-06-01

    In five separate blocks over a period of several months for 33 female rats the amount of geomagnetic activity during the day before ad libitum access to 10% sucrose or water was positively correlated with the volume of sucrose consumed per 24-hr. period. The strength of the correlation (.62 to .77) declined over the subsequent 10 days from between .12 to -.18 and resembled an extinction curve. In a subsequent experiment four rats exposed to 5 nT to 8 nT, 0.5-Hz magnetic fields that ceased for 30 min. once every 4 hr. for 4 days consumed 11% more sucrose than the four rats exposed to no field. We suggest that the initial consumption of 10% sucrose may have been reinforced because it diminished the aversive physiological effects associated with the increased geomagnetic activity. However, over the subsequent days, as geomagnetic activity decreased or habituation occurred, negative reinforcement did not maintain this behavior.

  10. Innovative techniques to analyze time series of geomagnetic activity indices

    NASA Astrophysics Data System (ADS)

    Balasis, Georgios; Papadimitriou, Constantinos; Daglis, Ioannis A.; Potirakis, Stelios M.; Eftaxias, Konstantinos

    2016-04-01

    Magnetic storms are undoubtedly among the most important phenomena in space physics and also a central subject of space weather. The non-extensive Tsallis entropy has been recently introduced, as an effective complexity measure for the analysis of the geomagnetic activity Dst index. The Tsallis entropy sensitively shows the complexity dissimilarity among different "physiological" (normal) and "pathological" states (intense magnetic storms). More precisely, the Tsallis entropy implies the emergence of two distinct patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a higher degree of organization, and (ii) a pattern associated with normal periods, which is characterized by a lower degree of organization. Other entropy measures such as Block Entropy, T-Complexity, Approximate Entropy, Sample Entropy and Fuzzy Entropy verify the above mentioned result. Importantly, the wavelet spectral analysis in terms of Hurst exponent, H, also shows the existence of two different patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a fractional Brownian persistent behavior (ii) a pattern associated with normal periods, which is characterized by a fractional Brownian anti-persistent behavior. Finally, we observe universality in the magnetic storm and earthquake dynamics, on a basis of a modified form of the Gutenberg-Richter law for the Tsallis statistics. This finding suggests a common approach to the interpretation of both phenomena in terms of the same driving physical mechanism. Signatures of discrete scale invariance in Dst time series further supports the aforementioned proposal.

  11. An association between geomagnetic activity and dream bizarreness.

    PubMed

    Lipnicki, Darren M

    2009-07-01

    Daily disturbances of the earth's magnetic field produce variations in geomagnetic activity (GMA) that are reportedly associated with widespread effects on human health and behaviour. Some of these effects could be mediated by an established influence of GMA on the secretion of melatonin. There is evidence from unrelated research that melatonin influences dream bizarreness, and it is hypothesised here that there is an association between GMA and dream bizarreness. Also reported is a preliminary test of this hypothesis, a case study in which the dreams recorded over 6.5 years by a young adult male were analysed. Reports of dreams from the second of two consecutive days of either low or high GMA (K index sum < or =6 or > or = 28) were self-rated for bizarreness on a 1-5 scale. Dreams from low GMA periods (n=69, median bizarreness=4) were found to be significantly more bizarre than dreams from high GMA periods (n=85, median bizarreness=3; p=0.006), supporting the hypothesised association between GMA and dream bizarreness. Studies with larger samples are needed to verify this association, and to determine the extent to which melatonin may be involved. Establishing that there is an association between GMA and dream bizarreness would have relevance for neurophysiological theories of dreaming, and for models of psychotic symptoms resembling bizarre dream events.

  12. A nonlinear dynamical analogue model of geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Klimas, A. J.; Baker, D. N.; Roberts, D. A.; Fairfield, D. H.; Buechner, J.

    1992-01-01

    Consideration is given to the solar wind-magnetosphere interaction within the framework of deterministic nonlinear dynamics. An earlier dripping faucet analog model of the low-dimensional solar wind-magnetosphere system is reviewed, and a plasma physical counterpart to that model is constructed. A Faraday loop in the magnetotail is considered, and the relationship of electric potentials on the loop to changes in the magnetic flux threading the loop is developed. This approach leads to a model of geomagnetic activity which is similar to the earlier mechanical model but described in terms of the geometry and plasma contents of the magnetotail. The model is characterized as an elementary time-dependent global convection model. The convection evolves within a magnetotail shape that varies in a prescribed manner in response to the dynamical evolution of the convection. The result is a nonlinear model capable of exhibiting a transition from regular to chaotic loading and unloading. The model's behavior under steady loading and also some elementary forms of time-dependent loading is discussed.

  13. Group planarian sudden mortality: Is the threshold around global geomagnetic activity ≥K6?

    PubMed Central

    Murugan, Nirosha J; Karbowski, Lukasz M; Mekers, William Ft; Persinger, Michael A

    2015-01-01

    Sudden deaths in groups of animals have been observed by field and laboratory biologists. We have measured mortalities in large group-housed planarian during the infrequent periods of very intense geomagnetic activity. In 13 separate episodes over the last 5 y we have observed the sudden death in our laboratory of hundreds of planarian if their density was about 1 worm per cc and the global geomagnetic activity was K≥6 the day before or the day of the observation of the mortality. Such mortality never occurred in other conditions or days. Both estimates of the "magnetic moment" of a planarian in magnetic fields above this threshold of sustained magnetic flux density as well as the magnetic energy within the planarian volume predict values that could affect phenomenon associated with the total numbers of pH-dependent charges within each worm. These conditions could affect the Levin-Burr bioelectrical signals and networks that affect patterning information and sustainability in whole living systems. The establishment of a central reservoir for the report of these transient events might allow Life Scientists to more fully appreciate the impact of these pervasive global stimuli upon dense groups of animals. PMID:27066174

  14. [Dependence of acoustic-motor reaction of healthy individuals from geomagnetic activity].

    PubMed

    Hryhor'ev, P E; Poskotynova, L V; Tsandekov, P A; Vaĭserman, A M

    2009-01-01

    During February-April, 2008 using special computer test, a daily monitoring of simple acoustic-motor reaction was carried out in 18 healthy tested individuals. We found a significant decrease in the speed of acoustic-motor reaction the day before and the same day geomagnetic disturbance occurred, as well as the same and 2-3 days after a geomagnetic calm occurred. Presumably, either an essential increase or a decreases of geomagnetic activity are adverse factors for the functional state of a central nervous system. PMID:19526866

  15. Experimental evidence in support of Joule heating associated with geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Devries, L. L.

    1971-01-01

    High resolution accelerometer measurements in the altitude region 140 to 300 km from a satellite in a near-polar orbit during a period of extremely high geomagnetic activity indicate that Joule heating is the primary source of energy for atmospheric heating associated with geomagnetic activity. This conclusion is supported by the following observational evidence: (1) There is an atmospheric response in the auroral zone which is nearly simulataneous with the onset of geomagnetic activity, with no significant response in the equatorial region until several hours later; (2) The maximum heating occurs at geographic locations near the maximum current of the auroral electrojet; and (3) There is evidence of atmospheric waves originating near the auroral zone at altitudes where Joule heating would be expected to occur. An analysis of atmospheric response time to this heat shows time delays are apparently independent of altitude but are strongly dependent upon geomagnetic latitude.

  16. Terminator field-aligned current system: Its dependencies on solar, seasonal, and geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Schunk, R. W.; Eccles, V.; Scherliess, L.; Sojka, J. J.; Gardner, L. C.

    2015-12-01

    A new field-aligned current system in the high-latitude ionosphere was reported recently by Zhu et al. (2014). The current system develops and evolves along the ionospheric terminator and it is thus termed as the terminator field-aligned currents. The discovery was based on the reconstructions from the Ionospheric Dynamics and Electrodynamics Data Assimilation Model (IDED-DA) with the ingestion of observational measurements. In this presentation, we show the results of a follow-on study using the IDED-DA, in which the solar, seasonal, and geomagnetic dependencies of the terminator field-aligned currents are explored. The new current system is the first field-aligned current system in the high-latitude ionosphere that is not directly driven by the magnetospheric dynamics and has an ionospheric origin. A systematic study of its electrodynamic and plasma dynamics as well as dependencies on various solar-terrestrial conditions will help us to explore the active role of the ionosphere in the magnetosphere-ionosphere coupling and improve the physical understanding of the electrodynamics and plasma dynamics of many small-scale structures in the polar ionosphere.

  17. Long-term prediction of solar and geomagnetic activity daily time series using singular spectrum analysis and fuzzy descriptor models

    NASA Astrophysics Data System (ADS)

    Mirmomeni, M.; Kamaliha, E.; Shafiee, M.; Lucas, C.

    2009-09-01

    Of the various conditions that affect space weather, Sun-driven phenomena are the most dominant. Cyclic solar activity has a significant effect on the Earth, its climate, satellites, and space missions. In recent years, space weather hazards have become a major area of investigation, especially due to the advent of satellite technology. As such, the design of reliable alerting and warning systems is of utmost importance, and international collaboration is needed to develop accurate short-term and long-term prediction methodologies. Several methods have been proposed and implemented for the prediction of solar and geomagnetic activity indices, but problems in predicting the exact time and magnitude of such catastrophic events still remain. There are, however, descriptor systems that describe a wider class of systems, including physical models and non-dynamic constraints. It is well known that the descriptor system is much tighter than the state-space expression for representing real independent parametric perturbations. In addition, the fuzzy descriptor models as a generalization of the locally linear neurofuzzy models are general forms that can be trained by constructive intuitive learning algorithms. Here, we propose a combined model based on fuzzy descriptor models and singular spectrum analysis (SSA) (FD/SSA) to forecast a number of geomagnetic activity indices in a manner that optimizes a fuzzy descriptor model for each of the principal components obtained from singular spectrum analysis and recombines the predicted values so as to transform the geomagnetic activity time series into natural chaotic phenomena. The method has been applied to predict two solar and geomagnetic activity indices: geomagnetic aa and solar wind speed (SWS) of the solar wind index. The results demonstrate the higher power of the proposed method-- compared to other methods -- for predicting solar activity.

  18. ISEE 3 observations during the CDAW 8 intervals: Case studies of the distant geomagnetic tail covering a wide range of geomagnetic activity

    SciTech Connect

    Richardson, I.G.; Owen, C.J.; Cowley, S.W.H. ); Galvin, A.B. ); Sanderson, T.R. ); Scholer, M. ); Slavin, J.A. ); Zwickl, R.D. )

    1989-11-01

    The data obtained by the ISEE 3 spacecraft during the eight Coordinated Data Analysis Workshop 8 (CDAW 8) intervals provide an excellent opportunity to study the structure and dynamics of the distant geomagnetic tail under a wide range of geomagnetic activity ranging from intervals of magnetic quiet punctuated by isolated substorms to extended intervals of strong disturbance. By examining the properties of the plasma sheet, evidence has been found for the persistence of reconnection in the tail during long intervals of magnetic quiet, with the neutral line lying {approx}100 to 200 R{sub E} or more downtail. The suggestion that the distant tail plasma sheet is populated exclusively by tailward moving closed flux tubes under quiet geomagnetic conditions is therefore not supported. However, a slow plasma sheet regime is also found during such conditions, in which closed flux tubes move slowly tailward in a thick region adjacent to the magnetopause, presumably due to some form of viscous momentum transfer from the magnetosheath. This process does not appear to simultaneously transfer mass into the tail, and there is some indication that the Kelvin-Helmholtz instability is involved. The observations strongly suggest that the closed flux tubes originate from the closed field line plasma sheet region earthward of the neutral line rather than, for example, from the near-Earth low-latitude boundary layer. Plasmoids are observed in the distant tail following disturbance enhancements, the time of their appearance being generally consistent with disconnection from the near-Earth region at the time of the enhancement. Their structure is entirely consistent with the neutral line model.

  19. Excitation of electromagnetic ion cyclotron waves under different geomagnetic activities: THEMIS observation and modeling

    NASA Astrophysics Data System (ADS)

    Zhou, Qinghua; Xiao, Fuliang; Shi, Jiankui; Yang, Chang; He, Yihua; Tang, Lijun

    2013-01-01

    Understanding excitation of electromagnetic ion cyclotron (EMIC) waves remains a considerable scientific challenge in the magnetospheric physics. Here we adopt correlated data from the Thermal Emission Imaging System (THEMIS) spacecraft under low (Kp = 1+) and medium (Kp = 4) geomagnetic activities to investigate the favorable conditions for the excitation of EMIC waves. We utilize a sum of bi-Maxwellian components and kappa components to fit the observed ion (6-25 keV) distributions collected by the electrostatic analyzer (ESA) onboard the THEMIS spacecraft. We show that the kappa distribution models better and more smoothly with the observations. Then we evaluate the local growth rate and path-integrated gain of EMIC waves by bi-Maxwellian and kappa distributions, respectively. We demonstrate that the path-integrated wave gain simulated from the kappa distribution is consistent with observations, with intensities 24 dB in H+ band and 33 dB in He+ band. However, bi-Maxwellian distribution tends to overestimate the wave growth rate and path-integrated gain, with intensities 49 dB in H+ band and 48 dB in He+ band. Moreover, compared to the He+ band, a higher proton anisotropy is needed to excite the H+ band waves. The current study presents a further observational support for the understanding of EMIC wave instability under different geomagnetic conditions and suggests that the kappa-type distributions representative of the power law spectra are probably ubiquitous in space plasmas.

  20. Cosmic Rays during Intense Geomagnetic Conditions and their Solar / Interplanetary features

    NASA Astrophysics Data System (ADS)

    Kaushik, Subhash Chandra

    In this study we discuss the behavior of cosmic rays during the phase of highly intense or ultra intense geomagnetic storms, as shocks driven by energetic coronal mass ejections (CME’s) and other interplanetary (IP) transients are mainly responsible for initiating large and intense geomagnetic storms. Observational results indicate that galactic cosmic rays (CR) coming from deep surface interact with these abnormal solar and IP conditions and suffer modulation effects. In this paper a systematic study has been performed to analyze the CRI variation during super storms i.e. very intense geomagnetic storms with Dst index ≥ -300 nT. The neutron monitor data of three stations Oulu (Rc = 0.77 GV), Climax (Rc = 2.97 GV) and Huancayo (Rc = 13.01 GV) well distributed over different latitudes and hourly values of IMF parameters derived from satellite observations near Earth IP medium from OMNI Data base is used for the period spanning over solar cycles 20, 21, 22 and 23. It is found that AP and AE indices show rise before the forward turnings of IMF, while the Dst index shows a classic storm time decrease. The analysis indicates that the magnitude of all the responses depends on BZ component of IMF being well correlated with solar maximum and minimum periods. Transient decrease in cosmic ray intensity with slow recovery is observed during the storm phase duration.

  1. Short-term forecasting regional model to predict M(3000)F2 over the European sector: Comparisons with the IRI model during moderate, disturbed, and very disturbed geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Pietrella, M.

    2014-07-01

    The hourly measurements of M(3000)F2 (M(3000)F2meas) and the hourly quiet-time values of M(3000)F2 (M(3000)F2QT) relative to the ionospheric observatories of Poitiers, Lannion, Dourbes, Slough, Rome, Juliusruh, Kaliningrad, Uppsala, Lyckesele, Sodankyla, and Kiruna as well as the hourly time-weighted accumulation series derived from the geomagnetic planetary index ap (ap(τ), were considered during the period January 1957-December 2003 and used for the development of 11 short-term forecasting local models (STFLM) of M(3000)F2. Under the assumption that the ionospheric disturbance index ln(M(3000)F2meas/M(3000)F2QT) is correlated to the integrated geomagnetic index ap(τ), a set of regression coefficients were established over 12 months and 24 h for each of the 11 observatories under consideration and used as input to calculate the short-term ionospheric forecasting of M(3000)F2 for three different ranges of geomagnetic activity. The 11 short-term forecasting local models all together constitute a single short-term forecasting regional model (STFRM) of M(3000)F2. The monthly median predictions of M(3000)F2 provided by the IRI model at the 11 local stations were used to make some comparisons with the predictions of M(3000)F2 carried out by the STFRM. The results showed that: (1) under moderate geomagnetic activity there are no significantly differences between STFRM and IRI performance because quiet geomagnetic conditions are not so diverse from moderate geomagnetic conditions; (2) under disturbed geomagnetic activity, performances of STFRM significantly better than IRI emerge only in some cases; (3) the STFRM's performances are always significantly better than those provided by IRI under very disturbed geomagnetic activity, consequently the operative use of the STFRM could be valuable in providing short-term forecasting maps of M(3000)F2 over the European area during very disturbed geomagnetic conditions.

  2. Latitudinal variation of 732.0 nm dayglow emission under geomagnetic storm conditions

    NASA Astrophysics Data System (ADS)

    Singh, Vir; Dharwan, Maneesha

    2016-07-01

    A comprehensive model is developed to study 732.0 nm dayglow emission. The Solar2000 EUV (extreme ultraviolet) flux model, neutral atmosphere model (NRLMSISE-00), latest transition probabilities and updated reaction rate coefficients are incorporated in the present model. The modeled volume emission rates (VER) are compared with the measurements as provided by Atmosphere Explorer-C satellite, Dynamics Explorer-2 spacecraft and WINDII measurements. The model is found in very good agreement with the measurements. This model is used to study the effects of geomagnetic storm on the 732.0 nm dayglow emission at various latitudes in northern hemisphere. It is found that the VER decreases as the latitude increases. The decrease in VER from low to mid latitudes is due to the decrease in atomic oxygen number density with latitude. The zenith intensity at the maximum geomagnetic activity is about 15% higher than the zenith intensity before the start of the geomagnetic storm in equatorial region. However, no appreciable change in the zenith intensity is found at higher latitudes (above 50° N). Further a negative correlation is found between the volume emission rate and DST index at all latitudes.

  3. Performance evaluation of selected ionospheric delay models during geomagnetic storm conditions in low-latitude region

    NASA Astrophysics Data System (ADS)

    Venkata Ratnam, D.; Sarma, A. D.; Satya Srinivas, V.; Sreelatha, P.

    2011-06-01

    Investigation of space weather effects on GPS satellite navigation systems is very crucial in high-precision positional applications such as aircraft landings and missile guidance, etc. The geomagnetic storms can drastically affect the total electron content (TEC) of the ionosphere even in low latitudes, especially for Indian region as it comes under low-latitude region. Hence, the performance of three prominent ionospheric models is investigated for adverse ionospheric conditions using 17 GPS TEC stations data. The models characterized the ionospheric disturbances due to two magnetic storms well.

  4. The dependence on geomagnetic conditions and solar wind dynamic pressure of the spatial distributions of EMIC waves observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Saikin, A. A.; Zhang, J.-C.; Smith, C. W.; Spence, H. E.; Torbert, R. B.; Kletzing, C. A.

    2016-05-01

    A statistical examination on the spatial distributions of electromagnetic ion cyclotron (EMIC) waves observed by the Van Allen Probes against varying levels of geomagnetic activity (i.e., AE and SYM-H) and dynamic pressure has been performed. Measurements taken by the Electric and Magnetic Field Instrument Suite and Integrated Science for the first full magnetic local time (MLT) precession of the Van Allen Probes (September 2012-June 2014) are used to identify over 700 EMIC wave events. Spatial distributions of EMIC waves are found to vary depending on the level of geomagnetic activity and solar wind dynamic pressure. EMIC wave events were observed under quiet (AE ≤ 100 nT, 325 wave events), moderate (100 nT < AE ≤ 300 nT, 218 wave events), and disturbed (AE > 300 nT, 228 wave events) geomagnetic conditions and are primarily observed in the prenoon sector (~800 < MLT ≤ ~1100) at L ≈ 5.5 during quiet activity times. As AE increases to disturbed levels, the peak occurrence rates shift to the afternoon sector (1200 < MLT ≤ 1800) between L = 4 and L = 6. A majority of EMIC wave events (~56%) were observed during nonstorm times (defined by SYM-H). Consistent with the quiet AE levels, nonstorm EMIC waves are observed in the prenoon sector. EMIC waves observed through the duration of a geomagnetic storm are primarily located in the afternoon sector. High solar wind pressure (Pdyn > 3 nPa) correlates to mostly afternoon EMIC wave observations.

  5. Influence of solar wind variability on geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Garrett, H. B.; Dessler, A. J.; Hill, T. W.

    1974-01-01

    A statistical study of solar wind data from the Explorer 33 satellite shows that interplanetary magnetic field irregularities are enhanced in the interaction region where a fast solar wind stream overtakes a slower solar wind stream. Comparison with geomagnetic AE and ap indexes further shows that these interplanetary irregularities enhance the level of geomagnetic disturbances. Thus while substorm occurrence is highly correlated with the dawn-dusk component of the solar wind electric field, the amplitude of the substorms is an increasing function of the variance in the interplanetary field. This result can be interpreted as a capacitative effect of the magnetopause that allows a time-varying solar wind electric field to penetrate the magnetosphere more effectively than a static solar wind electric field.

  6. Did Geomagnetic Activity Challenge Electric Power Reliability During Solar Cycle 23? Evidence from the PJM Regional Transmission Organization in North America

    NASA Technical Reports Server (NTRS)

    Forbes, Kevin F.; Cyr, Chris St

    2012-01-01

    During solar cycle 22, a very intense geomagnetic storm on 13 March 1989 contributed to the collapse of the Hydro-Quebec power system in Canada. This event clearly demonstrated that geomagnetic storms have the potential to lead to blackouts. This paper addresses whether geomagnetic activity challenged power system reliability during solar cycle 23. Operations by PJM Interconnection, LLC (hereafter PJM), a regional transmission organization in North America, are examined over the period 1 April 2002 through 30 April 2004. During this time PJM coordinated the movement of wholesale electricity in all or parts of Delaware, Maryland, New Jersey, Ohio, Pennsylvania, Virginia, West Virginia, and the District of Columbia in the United States. We examine the relationship between a proxy of geomagnetically induced currents (GICs) and a metric of challenged reliability. In this study, GICs are proxied using magnetometer data from a geomagnetic observatory located just outside the PJM control area. The metric of challenged reliability is the incidence of out-of-economic-merit order dispatching due to adverse reactive power conditions. The statistical methods employed make it possible to disentangle the effects of GICs on power system operations from purely terrestrial factors. The results of the analysis indicate that geomagnetic activity can significantly increase the likelihood that the system operator will dispatch generating units based on system stability considerations rather than economic merit.

  7. Geomagnetic activity associated with earth passage of interplanetary shock disturbances and coronal mass ejections

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.; Mccomas, D. J.; Phillips, J. L.; Bame, S. J.

    1991-01-01

    Coronal mass ejection events (CMEs) are important occasional sources of plasma and magnetic field in the solar wind at 1 AU, accounting for approximately 10 percent of all solar wind measurements in the ecliptic plane during the last solar activity maximum. Using a recently appreciated capability for distinguishing CMEs in solar wind data in the form of counterstreaming solar wind electron events, this paper explores the overall effectiveness of shock wave disturbances and CMFs in general in stimulating geomagnetic activity. The study is confined to the interval from mid-August 1978 through mid-October 1982, spanning the last solar activity maximum, when ISEE 3 was in orbit about the L1 Lagrange point 220 Re upstream from earth. It is found that all but one of the 37 largest geomagnetic storms in that era were associated with earth passage of CMEs and/or shock disturbances, with the large majority of these storms (27 out of 37) being associated with interplanetary events where earth encountered both a shock and the CME driving the shock (shock/CME events). Although CMEs and/or shock disturbances were increasingly the cause of geomagnetic activity as the level of geomagnetic activity increased, many smaller geomagnetic disturbances were unrelated to these events.

  8. Reaction of physiological factors on the solar-geomagnetic activity (the physical mechanisms)

    NASA Astrophysics Data System (ADS)

    Avakyan, Sergey; Voronin, Nikolai; Dubarenko, Konstantin

    , combined consideration of geo-electromagnetic radiation with carrier microwave frequency whose amplitude is modulated with the low-frequency (informational) component, is very promising. Indeed, in the Earth ionosphere the Schumann resonator is located between the Earth’s surface and the ionosphere region at the heights of 100 to 150 km (under Е-layer), while the Alfven resonator is substantially larger and occupies the entire F-region of the ionosphere, up to its upper part at the heights roughly 1000 km above the surface. Since virtually all characteristics of the ionosphere medium are specified by solar activity (and also by geomagnetic activity - at high latitudes, and even, in the case of the principal magnetic storms, at middle latitudes), the parameters of both resonators, in particular, such as the functional frequencies and Q-factor, reflect the current level of the activities, including their most powerful manifestations in cosmic weather perturbations: solar flares and geomagnetic storms. The experimental data related to helio-geo-biocorrelations indicate that the impact of solar flares, and, which is more important, of magnetic storms on patients with cardiovascular and cerebral circulation pathology is based on the increase of the blood viscosity under the influence of the amplified microwave radiation of the ionosphere, immunodisfunction develops due to deterioration of the quality of leukocytes under the same conditions as above, and the excitatory system is affected with microwave resonance at the frequencies of VLF - ELF amplitude modulation in Schumann (at frequencies above 7 Hz) and Alfven (at frequencies below 6 Hz and down to minor fractions of a Hertz) bands, which are close to basic rhythms of human brain. Indeed, these resonators display a set of basic frequencies: 6 - 7 to 40 Hz (Schumann’s) and 0,1 to 6 Hz (Alfven’s). In the first case, the resonance frequencies (roughly equal to 7.7, 13.8, 19.7, and 26.7 Hz) are consistent with Alpha, Beta

  9. Effect of geomagnetic activity on equatorial radio VHF scintillations and spread F

    SciTech Connect

    Rastogi, R.G.; Mullen, J.P.; MacKenzie, E.

    1981-05-01

    The paper discusses the occurrence of scintillations of ATS 3 (137 MHz) beacons recorded at Huancayo on geomagnetically quiet and disturbed days during the years 1969--1976 and compared the results with the corresponding occurrence of range and frequency spread F at Huancayo. During the equinoctial months and the December solstical months the geomgnetic activity reduces the equatorial scintillations during premidnight hours but increases their occurrence during the postmidnight hours. These features are very similar to the effect of geomagnetic activity on the occurrence of the range type of equatorial spread F rather than on the occurrence of frequency spread, which decreases for any hour of the night during geomagnetic active periods. During the June solsticial months, the occurrence of both scintillations and spread F is very much reduced; however, both the phenomena are more frequent on disturbed than on quiet days for any of the hours of the night. These effects are consistently the same for any of the years within the solar cycle. It is suggested that the equatorial radio scintillations at 137 MHz during the nighttime are produced primarily by the occurrence of the range type of spread F. The geomagnetic effects are due to the modifications of the equatorial electric field by the geomagnetic disturbance and thereby affect the development of F region irregularities causing scintillations.

  10. Persistence in recurrent geomagnetic activity and its connection with Space Climate

    NASA Astrophysics Data System (ADS)

    Diego, P.; Storini, M.; Laurenza, M.

    2010-06-01

    Recurrent geomagnetic activity is mainly linked to the passage of interplanetary corotating solar wind structures in the near-Earth space. We studied geomagnetic recurrences for which an enhanced value of the autocorrelation coefficient exists between the data of two adjacent Bartels rotations in aa, Kp, Dst, AE time series, for the period 1954-2007, covering about 5 solar cycles (from cycle 19 to cycle 23). A new index (P), based on autocorrelation analysis, has been introduced to estimate also the duration up to seven Bartels rotations of each solar structure (or group of structures) producing geomagnetic recurrences with high autocorrelation (correlation coefficient ≥ 0.3). We could infer whether recurrent geomagnetic activity is due to successive short-lived (at least 2 Bartels rotations) or to long-lasting corotating structures (up to 7 or more Bartels rotations). Generally, time periods characterized by recurrent geomagnetic activity are longer during the descending phase of even-numbered cycles (20, 22). Nevertheless, we found that recurrences determined by long-lived interplanetary structures are detected mainly in the descending phase of cycles 19 and 23. Finally, we point out that the average levels of the computed indices during the descending phase of each solar cycle show a significant anticorrelation with the sunspot area integrated over the subsequent cycle, giving new insights for Space Climate forecast.

  11. Formation of Polar Ionospheric Tongue of Ionization during Minor Geomagnetic Disturbed Conditions

    NASA Astrophysics Data System (ADS)

    Liu, J.; Wang, W.; Burns, A. G.; Yue, X.; Zhang, S.; Zhang, Y.

    2015-12-01

    Previous investigations of ionospheric storm-enhanced density (SED) and tongue of ionization (TOI) focused mostly on the behavior of TOI during intense geomagnetic storms. Little attention has been paid to the spatial and temporal variations of TOI during weak to moderate geomagnetic disturbed conditions. we investigate the source and development of TOI during a moderate geomagnetic storm on 14 October 2012.Multi-instrumental observations including GPS total electron content (TEC), Defense Meteorological SatelliteProgram(DMSP) in situ measured total ion concentration and ion drift velocity, SuperDARN measured polar ionconvection patterns, and electron density profiles from the Poker Flat Incoherent Scatter Radar (PFISR) have been utilized in the current analysis. GPS TEC maps show salient TOI structures persisting for about 5 h over high latitudes of North America on 14 October 2012 in the later recovery phase of the storm when the magnitudes of IMF By and Bz were less than 5 nT. The PFISR electron density profiles indicate that the extra ionization for TEC enhancements mainly occurred in the topside ionosphere with no obvious changes in the bottom side ionosphere and vertical plasma drifts. Additionally, there were no signatures of penetration electric fields in the equatorial electrojet data and upward ion drifts at high latitudes. At the same time, strong subauroral polarization streams with ion drift speeds exceeding 2.5 km/s carried sunward fluxes and migrated toward lower latitudes for about 5° based on the DMSP cross-track driftmeasurements. Based on those measurements,we postulate that the combined effects of initial build-up of ionization at midlatitudes through daytime production of ionization and equatorward (or less poleward than normal daytime) neutral wind reducing downward diffusion along the inclined filed lines, and an expanded polar ion convection pattern and its associated horizontal plasma transport are important in the formation of the TOI.

  12. Formation of polar ionospheric tongue of ionization during minor geomagnetic disturbed conditions

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Nakamura, Takuji; Liu, Libo; Wang, Wenbin; Balan, Nanan; Nishiyama, Takanori; Hairston, Marc R.; Thomas, E. G.

    2015-08-01

    Previous investigations of ionospheric storm-enhanced density (SED) and tongue of ionization (TOI) focused mostly on the behavior of TOI during intense geomagnetic storms. Little attention has been paid to the spatial and temporal variations of TOI during weak to moderate geomagnetic disturbed conditions. In this paper we investigate the source and development of TOI during a moderate geomagnetic storm on 14 October 2012. Multi-instrumental observations including GPS total electron content (TEC), Defense Meteorological Satellite Program (DMSP) in situ measured total ion concentration and ion drift velocity, SuperDARN measured polar ion convection patterns, and electron density profiles from the Poker Flat Incoherent Scatter Radar (PFISR) have been utilized in the current analysis. GPS TEC maps show salient TOI structures persisting for about 5 h over high latitudes of North America on 14 October 2012 in the later recovery phase of the storm when the magnitudes of IMF By and Bz were less than 5 nT. The PFISR electron density profiles indicate that the extra ionization for TEC enhancements mainly occurred in the topside ionosphere with no obvious changes in the bottomside ionosphere and vertical plasma drifts. Additionally, there were no signatures of penetration electric fields in the equatorial electrojet data and upward ion drifts at high latitudes. At the same time, strong subauroral polarization streams with ion drift speeds exceeding 2.5 km/s carried sunward fluxes and migrated toward lower latitudes for about 5° based on the DMSP cross-track drift measurements. Based on those measurements, we postulate that the combined effects of initial build-up of ionization at midlatitudes through daytime production of ionization and equatorward (or less poleward than normal daytime) neutral wind reducing downward diffusion along the inclined filed lines, and an expanded polar ion convection pattern and its associated horizontal plasma transport are important in the

  13. Statistical Characteristics of EMIC Waves Observed at Geosynchronous Orbit during Quiet Geomagnetic Conditions

    NASA Astrophysics Data System (ADS)

    Park, J. S.; Kim, K. H.; Lee, D. H.; Lee, E.; Jin, H.

    2014-12-01

    It is generally accepted that the electromagnetic ion cyclotron (EMIC) waves can be generated under the conditions of anisotropic (T⊥ > T∥) and energetic (larger than a few tens keV) ion population. Such conditions are expected when the magnetospheric convection is enhanced or when the magnetosphere is compressed by solar wind dynamic pressure enhancement. Even in the absence of strong magnetospheric convection or strong solar wind dynamic pressure enhancements, we have observed EMIC waves at geosynchronous orbit. In this study, we report the GOES observations of the EMIC waves excited during quiet geomagnetic conditions (Kp ≤ 1) in the period from January 2007 to December in 2008. Unlike previous studies, the occurrence rate of quiet time EMIC waves is dominant in morning-to-afternoon sector. We will examine the source of free energy to excite quiet time EMIC waves and also examine wave's characteristics.

  14. Empirical regional models for the short-term forecast of M3000F2 during not quiet geomagnetic conditions over Europe

    NASA Astrophysics Data System (ADS)

    Pietrella, M.

    2013-10-01

    Twelve empirical local models have been developed for the long-term prediction of the ionospheric characteristic M3000F2, and then used as starting point for the development of a short-term forecasting empirical regional model of M3000F2 under not quiet geomagnetic conditions. Under the assumption that the monthly median measurements of M3000F2 are linearly correlated to the solar activity, a set of regression coefficients were calculated over 12 months and 24 h for each of 12 ionospheric observatories located in the European area, and then used for the long-term prediction of M3000F2 at each station under consideration. Based on the 12 long-term prediction empirical local models of M3000F2, an empirical regional model for the prediction of the monthly median field of M3000F2 over Europe (indicated as RM_M3000F2) was developed. Thanks to the IFELM_foF2 models, which are able to provide short-term forecasts of the critical frequency of the F2 layer (foF2STF) up to three hours in advance, it was possible to considerer the Brudley-Dudeney algorithm as a function of foF2STF to correct RM_M3000F2 and thus obtain an empirical regional model for the short-term forecasting of M3000F2 (indicated as RM_M3000F2_BD) up to three hours in advance under not quiet geomagnetic conditions. From the long-term predictions of M3000F2 provided by the IRI model, an empirical regional model for the forecast of the monthly median field of M3000F2 over Europe (indicated as IRI_RM_M3000F2) was derived. IRI_RM_M3000F2 predictions were modified with the Bradley-Dudeney correction factor, and another empirical regional model for the short-term forecasting of M3000F2 (indicated as IRI_RM_M3000F2_BD) up to three hours ahead under not quiet geomagnetic conditions was obtained. The main results achieved comparing the performance of RM_M3000F2, RM_M3000F2_BD, IRI_RM_M3000F2, and IRI_RM_M3000F2_BD are (1) in the case of moderate geomagnetic activity, the Bradley-Dudeney correction factor does not

  15. On cosmic rays flux variations in midlatitudes and their relations to geomagnetic and atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Morozova, Anna; Blanco, Juan Jose; Mendes Ribeiro, Paulo Fernando

    The cosmic rays flux is globally modulated by the solar cycle and shows anti-correlation with the sunspot number. Near to the Earth it is modulated by the solar wind and the Earth's magnetic field. The analysis of the secondary cosmic rays produced when they interact in the low stratosphere allows extracting information about solar wind structures surrounding Earth's orbit, the magnetic field of the Earth and the temperature of the stratosphere. Recently, a new cosmic ray detector, the TRAGALDABAS, composed by RPC (Resistive Plate Chamber) planes, has been developed and installed to go deeper into the understanding of the cosmic rays arriving to the Earth surface. An international collaboration has been organized for keeping the detector operative and for analyzing the data. Here we present the analysis of the cosmic rays flux variations measured by two cosmic rays detectors of different types located in Spain (Castilla-La Mancha Neutron Monitor - CaLMa - in Guadalajara and TRAGALDABAS in Santiago de Compostela) and their comparison to changes both in the geomagnetic field components measured by the Coimbra Geomagnetic Observatory (Portugal) and in the atmospheric conditions (tropo- and stratosphere) measured by Spanish and Portuguese meteorological stations. The study is focused on a number of recent cosmic rays events and pays specific attention to the comparison of the CaLMa series and the preliminary TRAGALDABAS data.

  16. Real-time Neural Network predictions of geomagnetic activity indices

    NASA Astrophysics Data System (ADS)

    Bala, R.; Reiff, P. H.

    2009-12-01

    The Boyle potential or the Boyle Index (BI), Φ (kV)=10-4 (V/(km/s))2 + 11.7 (B/nT) sin3(θ/2), is an empirically-derived formula that can characterize the Earth's polar cap potential, which is readily derivable in real time using the solar wind data from ACE (Advanced Composition Explorer). The BI has a simplistic form that utilizes a non-magnetic "viscous" and a magnetic "merging" component to characterize the magnetospheric behavior in response to the solar wind. We have investigated its correlation with two of conventional geomagnetic activity indices in Kp and the AE index. We have shown that the logarithms of both 3-hr and 1-hr averages of the BI correlate well with the subsequent Kp: Kp = 8.93 log10(BI) - 12.55 along with 1-hr BI correlating with the subsequent log10(AE): log10(AE) = 1.78 log10(BI) - 3.6. We have developed a new set of algorithms based on Artificial Neural Networks (ANNs) suitable for short term space weather forecasts with an enhanced lead-time and better accuracy in predicting Kp and AE over some leading models; the algorithms omit the time history of its targets to utilize only the solar wind data. Inputs to our ANN models benefit from the BI and its proven record as a forecasting parameter since its initiation in October, 2003. We have also performed time-sensitivity tests using cross-correlation analysis to demonstrate that our models are as efficient as those that incorporates the time history of the target indices in their inputs. Our algorithms can predict the upcoming full 3-hr Kp, purely from the solar wind data and achieve a linear correlation coefficient of 0.840, which means that it predicts the upcoming Kp value on average to within 1.3 step, which is approximately the resolution of the real-time Kp estimate. Our success in predicting Kp during a recent unexpected event (22 July ’09) is shown in the figure. Also, when predicting an equivalent "one hour Kp'', the correlation coefficient is 0.86, meaning on average a prediction

  17. Statistical analysis of the relationships of solar, geomagnetic and human activities

    NASA Astrophysics Data System (ADS)

    Gil, Agnieszka; Alania, Michael; Modzelewska, Renata

    Data of galactic cosmic rays, solar and geomagnetic activities, solar wind parameters and car accident events (CAE) in Poland have been analyzed in order to reveal the statistical relationships among them for the period of 1990- 2007. Cross correlation, cross spectrum and filters method have been used to analyze data of the galactic cosmic ray intensity, the solar wind (SW) velocity, DST, Kp index of geomagnetic activity and CAE in Poland. For some epochs of the above-mentioned period there is found a consistent relationship between CAE, parameters of solar and geomagnetic activities in various periodicities; e.g. the periodicity of 7 days is clearly revealed in CAE, in galactic cosmic rays, SW, solar and geomagnetic activities, especially for the minimum epoch of solar activity. We suppose that there is not excluded that the 7 day periodicity is partially related with the human social activities. The periodicity of 3.5 days, generally found only in the series of CAE data, more or less should be ascribed to the social activities, besides we have not an explicit physical-biological explanation of this effect.

  18. Forecasting geomagnetic activity indices using the Boyle index through artificial neural networks

    NASA Astrophysics Data System (ADS)

    Balasubramanian, Ramkumar

    2010-11-01

    Adverse space weather conditions affect various sectors making both human lives and technologies highly susceptible. This dissertation introduces a new set of algorithms suitable for short term space weather forecasts with an enhanced lead-time and better accuracy in predicting Kp, Dst and the AE index over some leading models. Kp is a 3-hour averaged global geomagnetic activity index good for midlatitude regions. The Dst index, an hourly index calculated using four ground based magnetic field measurements near the equator, measures the energy of the Earth's ring current. The Auroral Electrojet indices or AE indices are hourly indices used to characterize the global geomagnetic activity in the auroral zone. Our algorithms can predict these indices purely from the solar wind data with lead times up to 6 hours. We have trained and tested an ANN (Artificial Neural Network) over a complete solar cycle to serve this purpose. Over the last couple of decades, ANNs have been successful for temporal prediction problems amongst other advanced non-linear techniques. Our ANN-based algorithms receive near-real-time inputs either from ACE (Advanced Composition Explorer), located at L1, and a handful of ground-based magnetometers or only from ACE. The Boyle potential, phi = 10-4 (vkm/sec)2+ 11.7BnT sin3 (theta/2) kV, or the Boyle Index (BI) is an empirically-derived formula that approximates the Earth's polar cap potential and is easily derivable in real time using the solar wind data from ACE. The logarithms of both 3-hour and 1-hour averages of the Boyle Index correlate well with the subsequent Kp, Dst and AE: Kp = 8.93 log 10 - 12.55. Dst = 0.355 - 6.48, and AE = 5.87 - 83.46. Inputs to our ANN models have greatly benefitted from the BI and its proven record as a forecasting parameter since its initiation in October, 2003. A preconditioning event tunes the magnetosphere to a specific state before an impending geomagnetic storm. The neural net not only improves the

  19. Two-step forecast of geomagnetic storm using coronal mass ejection and solar wind condition

    PubMed Central

    Kim, R-S; Moon, Y-J; Gopalswamy, N; Park, Y-D; Kim, Y-H

    2014-01-01

    To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz ≤ −5 nT or Ey ≥ 3 mV/m for t≥ 2 h for moderate storms with minimum Dst less than −50 nT) and a Dst model developed by Temerin and Li (2002, 2006) (TL model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90%) than the forecasts based on the TL model (87%). However, the latter produces better forecasts for 24 nonstorm events (88%), while the former correctly forecasts only 71% of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80%) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (∩), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81%) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (∪), all geomagnetic storms are correctly forecasted. PMID:26213515

  20. No covariation between the geomagnetic activity and the incidence of acute myocardial infarction in the polar area of northern Sweden

    NASA Astrophysics Data System (ADS)

    Messner, T.; Häggström, I.; Sandahl, I.; Lundberg, V.

    2002-05-01

    This study was undertaken to investigate whether there was any relation between the aurora borealis (measured as the geomagnetic activity) and the number of acute myocardial infarctions (AMI) in the northern, partly polar, area of Sweden. The AMI cases were collected from The Northern Sweden MONICA (multinational MONItoring of trends and determinants of CArdiovascular disease) AMI registry between 1985 and 1998, inclusive, and the information on the geomagnetic activity from continuous measurements at the Swedish Institute of Space Physics, Kiruna. In the analyses, both the relation between the individual AMI case and ambient geomagnetic activity, and the relation between the mean daily K index and the daily number of AMI cases were tested. We found no statistically significant relation between the number of fatal or non-fatal AMI cases, the number of sudden deaths or the number of patients with chest pain without myocardial damage, and geomagnetic activity. Our data do not support a relation between the geomagnetic activity and AMI.

  1. Evaluation of a new paleosecular variation activity index as a diagnostic tool for geomagnetic field variations

    NASA Astrophysics Data System (ADS)

    Panovska, Sanja; Constable, Catherine

    2015-04-01

    Geomagnetic indices like Dst, K and A, have been used since the early twentieth century to characterize activity in the external part of the modern geomagnetic field and as a diagnostic for space weather. These indices reflect regional and global activity and serve as a proxy for associated physical processes. However, no such tools are yet available for the internal geomagnetic field driven by the geodynamo in Earth's liquid outer core. To some extent this reflects limited spatial and temporal sampling for longer timescales associated with paleomagnetic secular variation, but recent efforts in both paleomagnetic data gathering and modeling activity suggest that longer term characterization of the internal geomagnetic weather/climate and its variability would be useful. Specifically, we propose an index for activity in paleosecular variation, useful as both a local and global measure of field stability during so-called normal secular variation and as a means of identifying more extreme behavior associated with geomagnetic excursions and reversals. To date, geomagnetic excursions have been identified by virtual geomagnetic poles (VGPs) deviating more than some conventional limit from the geographic pole (often 45 degrees), and/or by periods of significant intensity drops below some critical value, for example 50% of the present-day field. We seek to establish a quantitative definition of excursions in paleomagnetic records by searching for synchronous directional deviations and lows in relative paleointensity. We combine paleointensity variations with deviations from the expected geocentric axial dipole (GAD) inclination in a single parameter, which we call the paleosecular variation (PSV) activity index. This new diagnostic can be used on any geomagnetic time series (individual data records, model predictions, spherical harmonic coefficients, etc.) to characterize the level of paleosecular variation activity, find excursions, or even study incipient reversals

  2. Prediction of Geomagnetic Activity and Key Parameters in High-latitude Ionosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Lyatsky, Wladislaw; Tan, Arjun; Ridley, Aaron

    2007-01-01

    Prediction of geomagnetic activity and related events in the Earth's magnetosphere and ionosphere are important tasks of US Space Weather Program. Prediction reliability is dependent on the prediction method, and elements included in the prediction scheme. Two of the main elements of such prediction scheme are: an appropriate geomagnetic activity index, and an appropriate coupling function (the combination of solar wind parameters providing the best correlation between upstream solar wind data and geomagnetic activity). We have developed a new index of geomagnetic activity, the Polar Magnetic (PM) index and an improved version of solar wind coupling function. PM index is similar to the existing polar cap PC index but it shows much better correlation with upstream solar wind/IMF data and other events in the magnetosphere and ionosphere. We investigate the correlation of PM index with upstream solar wind/IMF data for 10 years (1995-2004) that include both low and high solar activity. We also have introduced a new prediction function for the predicting of cross-polar-cap voltage and Joule heating based on using both PM index and upstream solar wind/IMF data. As we show such prediction function significantly increase the reliability of prediction of these important parameters. The correlation coefficients between the actual and predicted values of these parameters are approx. 0.9 and higher.

  3. Greater electroencephalographic coherence between left and right temporal lobe structures during increased geomagnetic activity.

    PubMed

    Saroka, Kevin S; Caswell, Joseph M; Lapointe, Andrew; Persinger, Michael A

    2014-02-01

    Interhemispheric coherence for 19 channel EEG activity collected over a three year period from 184 men and women who relaxed in a quiet, darkened chamber showed significant increased coherence between caudal temporal regions for the 11 Hz frequency band during increased (>∼8 nT) global geomagnetic activity at the time of measurement. Detailed analyses from source-localization indicated that a likely origin was the parahippocampal regions whose net differences at 10, 11 and 12 Hz intervals were significantly correlated with geomagnetic activity. Analyses of residuals to obtain a "purer" measure of parahippocampal contributions indicated that interhemispheric temporal lobe coherence across unit increments between 1 and 40 Hz revealed the most statistically significant peaks at 7.5 Hz and 19.5 Hz. These weak but reliable correlations between global geomagnetic activity and the degree of inter-temporal lobe coherence for normal people relaxing in a dark, quiet area are consistent with the results of multiple studies indicating that intrusive experiences such as "presences" or "hallucinations" are more frequent when global geomagnetic activity increases above ∼15-20 nT.

  4. A New Polar Magnetic Index of Geomagnetic Activity and its Application to Monitoring Ionospheric Parameters

    NASA Technical Reports Server (NTRS)

    Lyatsky, Wladislaw; Khazanov, George V.

    2008-01-01

    For improving the reliability of Space Weather prediction, we developed a new, Polar Magnetic (PM) index of geomagnetic activity, which shows high correlation with both upstream solar wind data and related events in the magnetosphere and ionosphere. Similarly to the existing polar cap PC index, the new, PM index was computed from data from two near-pole geomagnetic observatories; however, the method for computing the PM index is different. The high correlation of the PM index with both solar wind data and events in Geospace environment makes possible to improve significantly forecasting geomagnetic disturbances and such important parameters as the cross-polar-cap voltage and global Joule heating in high latitude ionosphere, which play an important role in the development of geomagnetic, ionospheric and thermospheric disturbances. We tested the PM index for 10-year period (1995-2004). The correlation between PM index and upstream solar wind data for these years is very high (the average correlation coefficient R approximately equal to 0.86). The PM index also shows the high correlation with the cross-polar-cap voltage and hemispheric Joule heating (the correlation coefficient between the actual and predicted values of these parameters is approximately 0.9), which results in significant increasing the prediction reliability of these parameters. Using the PM index of geomagnetic activity provides a significant increase in the forecasting reliability of geomagnetic disturbances and related events in Geospace environment. The PM index may be also used as an important input parameter in modeling ionospheric, magnetospheric, and thermospheric processes.

  5. Global Cosmic Ray Intensity Changes, Solar Activity Variations and Geomagnetic Disturbances as North Atlantic Hurricane Precursors

    NASA Astrophysics Data System (ADS)

    Kavlakov, S. P.

    It was shown that specific changes of the sunspots (SS) number, cosmic ray (CR) intensity and geomagnetic activity indices AP and KP were statistically noticeable in the interval of 30 days before the appearance of a cyclonic rotational system over the North Atlantic, developing gradually in a major hurricane.

  6. Revisiting geomagnetic activity at auroral latitudes: No need for regular quiet curve removal for geomagnetic activity indices based on hourly data

    NASA Astrophysics Data System (ADS)

    Martini, Daniel; Argese, Chiara; Di Loreto, Massimo; Mursula, Kalevi

    2016-07-01

    The main objective of our study is to determine if the regular quiet daily curve (QDC) subtraction is a necessary procedure in quantifying the irregular geomagnetic variations at auroral latitudes. We define the hourly ΔH index, the absolute hour-to-hour deviation in nanotesla of the hourly geomagnetic horizontal component, which assigns each sample to sample deviation as geomagnetic activity without separating the "regular" and "irregular" parts of the daily magnetic field evolution. We demonstrate that the hourly gradient of the regular Sq variation is very small with respect to the irregular part, and a bulk of the nominal daily variation is actually part of the variation driven by solar wind and interplanetary magnetic field and traditionally classified as irregular. Therefore, attempts to subtract QDC can lead to a larger error, often caused by residual deviations between the used different mathematical and methodological tools and corresponding presumptions themselves. We show that ΔH provides the best and most consistent results at most timescales with the highest effective resolution among the studied indices. We also demonstrate that the ΔH index may equally be useful as a quick-look near-real-time index of space weather and as a long-term index derived from hourly magnetometer data for space climate studies.

  7. Are secular correlations between sunspots, geomagnetic activity, and global temperature significant?

    USGS Publications Warehouse

    Love, J.J.; Mursula, K.; Tsai, V.C.; Perkins, D.M.

    2011-01-01

    Recent studies have led to speculation that solar-terrestrial interaction, measured by sunspot number and geomagnetic activity, has played an important role in global temperature change over the past century or so. We treat this possibility as an hypothesis for testing. We examine the statistical significance of cross-correlations between sunspot number, geomagnetic activity, and global surface temperature for the years 1868-2008, solar cycles 11-23. The data contain substantial autocorrelation and nonstationarity, properties that are incompatible with standard measures of cross-correlational significance, but which can be largely removed by averaging over solar cycles and first-difference detrending. Treated data show an expected statistically- significant correlation between sunspot number and geomagnetic activity, Pearson p < 10-4, but correlations between global temperature and sunspot number (geomagnetic activity) are not significant, p = 0.9954, (p = 0.8171). In other words, straightforward analysis does not support widely-cited suggestions that these data record a prominent role for solar-terrestrial interaction in global climate change. With respect to the sunspot-number, geomagnetic-activity, and global-temperature data, three alternative hypotheses remain difficult to reject: (1) the role of solar-terrestrial interaction in recent climate change is contained wholly in long-term trends and not in any shorter-term secular variation, or, (2) an anthropogenic signal is hiding correlation between solar-terrestrial variables and global temperature, or, (3) the null hypothesis, recent climate change has not been influenced by solar-terrestrial interaction. ?? 2011 by the American Geophysical Union.

  8. Trends of ionospheric irregularities over African low latitude region during quiet geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Mungufeni, Patrick; Habarulema, John Bosco; Jurua, Edward

    2016-02-01

    The occurrence patterns of ionospheric irregularities during quiet geomagnetic conditions over the African low latitude region were analysed. GNSS-derived Total Electron Content of the ionosphere data during the period 2001-2012 were used. The data were obtained from Libreville, Gabon (0.35°N, 9.68°E, geographic, 8.05°S, magnetic), Mbarara, Uganda (0.60°S, 30.74°E, geographic, 10.22°S, magnetic), and Malindi, Kenya (2.99°S, 40.19°E, geographic, 12.42°S, magnetic). The rate of change of total electron content index greater than 0.5 TECU/Min were considered as severe ionospheric irregularities. For most of the time, the strength of ionospheric irregularities in March equinox were greater than those during September equinox over East Africa and an opposite observation was made over West Africa. These asymmetries might be due to the direction of the meridional winds during equinoxes over the different stations. Severity of ionospheric irregularity reduced from west towards the east. This might have been related to the decreasing geomagnetic field strength from east towards the west. This is the first study that reveals the equinoctial asymmetry is different in the West and East African sectors. Moreover, the importance of this study lies in the fact that it has used extensive data to examine the isolated and un-explained earlier observations of equinoctial asymmetry and longitudinal variation of ionospheric irregularities over the African low latitude region.

  9. The effect of solar-geomagnetic activity during and after admission on survival in patients with acute coronary syndromes

    NASA Astrophysics Data System (ADS)

    Vencloviene, Jone; Babarskiene, Ruta; Milvidaite, Irena; Kubilius, Raimondas; Stasionyte, Jolanta

    2014-08-01

    A number of studies have established the effects of solar-geomagnetic activity on the human cardio-vascular system. It is plausible that the heliophysical conditions existing during and after hospital admission may affect survival in patients with acute coronary syndromes (ACS). We analyzed data from 1,413 ACS patients who were admitted to the Hospital of Kaunas University of Medicine, Lithuania, and who survived for more than 4 days. We evaluated the associations between active-stormy geomagnetic activity (GMA), solar proton events (SPE), and solar flares (SF) that occurred 0-3 days before and after admission, and 2-year survival, based on Cox's proportional-hazards model, controlling for clinical data. After adjustment for clinical variables, active-stormy GMA on the 2nd day after admission was associated with an increased (by 1.58 times) hazard ratio (HR) of cardiovascular death (HR = 1.58, 95 % CI 1.07-2.32). For women, geomagnetic storm (GS) 2 days after SPE occurred 1 day after admission increased the HR by 3.91 times (HR = 3.91, 95 % CI 1.31-11.7); active-stormy GMA during the 2nd-3rd day after admission increased the HR by over 2.5 times (HR = 2.66, 95 % CI 1.40-5.03). In patients aged over 70 years, GS occurring 1 day before or 2 days after admission, increased the HR by 2.5 times, compared to quiet days; GS in conjunction with SF on the previous day, nearly tripled the HR (HR = 3.08, 95 % CI 1.32-7.20). These findings suggest that the heliophysical conditions before or after the admission affect the hazard ratio of lethal outcome; adjusting for clinical variables, these effects were stronger for women and older patients.

  10. The effect of solar-geomagnetic activity during and after admission on survival in patients with acute coronary syndromes.

    PubMed

    Vencloviene, Jone; Babarskiene, Ruta; Milvidaite, Irena; Kubilius, Raimondas; Stasionyte, Jolanta

    2014-08-01

    A number of studies have established the effects of solar-geomagnetic activity on the human cardio-vascular system. It is plausible that the heliophysical conditions existing during and after hospital admission may affect survival in patients with acute coronary syndromes (ACS). We analyzed data from 1,413 ACS patients who were admitted to the Hospital of Kaunas University of Medicine, Lithuania, and who survived for more than 4 days. We evaluated the associations between active-stormy geomagnetic activity (GMA), solar proton events (SPE), and solar flares (SF) that occurred 0-3 days before and after admission, and 2-year survival, based on Cox's proportional-hazards model, controlling for clinical data. After adjustment for clinical variables, active-stormy GMA on the 2nd day after admission was associated with an increased (by 1.58 times) hazard ratio (HR) of cardiovascular death (HR=1.58, 95 % CI 1.07-2.32). For women, geomagnetic storm (GS) 2 days after SPE occurred 1 day after admission increased the HR by 3.91 times (HR=3.91, 95 % CI 1.31-11.7); active-stormy GMA during the 2nd-3rd day after admission increased the HR by over 2.5 times (HR=2.66, 95 % CI 1.40-5.03). In patients aged over 70 years, GS occurring 1 day before or 2 days after admission, increased the HR by 2.5 times, compared to quiet days; GS in conjunction with SF on the previous day, nearly tripled the HR (HR=3.08, 95 % CI 1.32-7.20). These findings suggest that the heliophysical conditions before or after the admission affect the hazard ratio of lethal outcome; adjusting for clinical variables, these effects were stronger for women and older patients.

  11. The effect of solar-geomagnetic activity during and after admission on survival in patients with acute coronary syndromes.

    PubMed

    Vencloviene, Jone; Babarskiene, Ruta; Milvidaite, Irena; Kubilius, Raimondas; Stasionyte, Jolanta

    2014-08-01

    A number of studies have established the effects of solar-geomagnetic activity on the human cardio-vascular system. It is plausible that the heliophysical conditions existing during and after hospital admission may affect survival in patients with acute coronary syndromes (ACS). We analyzed data from 1,413 ACS patients who were admitted to the Hospital of Kaunas University of Medicine, Lithuania, and who survived for more than 4 days. We evaluated the associations between active-stormy geomagnetic activity (GMA), solar proton events (SPE), and solar flares (SF) that occurred 0-3 days before and after admission, and 2-year survival, based on Cox's proportional-hazards model, controlling for clinical data. After adjustment for clinical variables, active-stormy GMA on the 2nd day after admission was associated with an increased (by 1.58 times) hazard ratio (HR) of cardiovascular death (HR=1.58, 95 % CI 1.07-2.32). For women, geomagnetic storm (GS) 2 days after SPE occurred 1 day after admission increased the HR by 3.91 times (HR=3.91, 95 % CI 1.31-11.7); active-stormy GMA during the 2nd-3rd day after admission increased the HR by over 2.5 times (HR=2.66, 95 % CI 1.40-5.03). In patients aged over 70 years, GS occurring 1 day before or 2 days after admission, increased the HR by 2.5 times, compared to quiet days; GS in conjunction with SF on the previous day, nearly tripled the HR (HR=3.08, 95 % CI 1.32-7.20). These findings suggest that the heliophysical conditions before or after the admission affect the hazard ratio of lethal outcome; adjusting for clinical variables, these effects were stronger for women and older patients. PMID:24018849

  12. The study of the midlatitude ionospheric response to geomagnetic activity at Nagycenk Geophysical Observatory

    NASA Astrophysics Data System (ADS)

    Berényi, Kitti; Kis, Árpád; Barta, Veronika; Novák, Attila

    2016-04-01

    Geomagnetic storms affect the ionospheric regions of the terrestrial upper atmosphere, causing several physical and chemical atmospheric processes. The changes and phenomena, which can be seen as a result of these processes, generally called ionospheric storm. These processes depend on altitude, term of the day, and the strength of solar activity, the geomagnetic latitude and longitude. The differences between ionospheric regions mostly come from the variations of altitude dependent neutral and ionized atmospheric components, and from the physical parameters of solar radiation. We examined the data of the ground-based radio wave ionosphere sounding instruments of the European ionospheric stations (mainly the data of Nagycenk Geophysical Observatory), called ionosonde, to determine how and what extent a given strength of a geomagnetic disturbance affect the middle latitude ionospheric regions in winter. We chose the storm for the research from November 2012 and March 2015. As the main result of our research, we can show significant differences between the each ionospheric (F1 and F2) layer parameters on quiet and strong stormy days. When we saw, that the critical frequencies (foF2) increase from their quiet day value, then the effect of the ionospheric storm was positive, otherwise, if they drop, they were negative. With our analysis, the magnitude of these changes could be determined. Furthermore we demonstrated, how a full strong geomagnetic storm affects the ionospheric foF2 parameter during different storm phases. It has been showed, how a positive or negative ionospheric storm develop during a geomagnetic storm. For a more completed analysis, we compared also the evolution of the F2 layer parameters of the European ionosonde stations on a North-South geographic longitude during a full storm duration. Therefore we determined, that the data of the ionosonde at Nagycenk Geophysical Observatory are appropriate, it detects the same state of ionosphere like the

  13. Lunisolar tidal waves, geomagnetic activity and epilepsy in the light of multivariate coherence.

    PubMed

    Mikulecky, M; Moravcikova, C; Czanner, S

    1996-08-01

    The computed daily values of lunisolar tidal waves, the observed daily values of Ap index, a measure of the planetary geomagnetic activity, and the daily numbers of patients with epileptic attacks for a group of 28 neurology patients between 1987 and 1992 were analyzed by common, multiple and partial cross-spectral analysis to search for relationships between periodicities in these time series. Significant common and multiple coherence between them was found for rhythms with a period length over 3-4 months, in agreement with seasonal variations of all three variables. If, however, the coherence between tides and epilepsy was studied excluding the influence of geomagnetism, two joint infradian periodicities with period lengths of 8.5 and 10.7 days became significant. On the other hand, there were no joint rhythms for geomagnetism and epilepsy when the influence of tidal waves was excluded. The result suggests a more primary role of gravitation, compared with geomagnetism, in the multivariate process studied. PMID:9181091

  14. PCA Analysis of the Geomagnetic Field at Mid-Latitude Regions during High Solar Activity

    NASA Astrophysics Data System (ADS)

    Natali, Maria Paula; Meza, Amalia Margarita

    2016-07-01

    Our study is focused on the analysis of the geomagnetic variability of the H, D and Z components in the Northern hemisphere at mid-latitudes. We analyze two different local times, noon and night, recorded by 22 permanent observatories distributed over Europe and North America during a period of four years of high solar activity comprising 2000-2003. We used Principal Component Analysis (PCA) in order to identify the spatial and temporal variations of the geomagnetic field components. This technique produces a quite compact representation of the data by defining an orthonormal base derived from correlation within the data set. This helps us to identify possible causes of seasonal variations and anomalies, linking them with already observed currents. In fact, the analysis of PCA amplitudes and modes support our interpretation of the spectral and statistical features of the geomagnetic field. Using the first two modes we reconstruct more than 90% of the original signal for the European and North American region. The obtained results reconfirm the existence of a latitudinal dependence in the geomagnetic components during nighttime hours, associated with the ring current. During noon, the first mode represent the dominant component of the current originated by the ionosphere, while the second mode show the presence of a longitudinal variation at both sides of the longitudes with zero declination for Europe and North America.

  15. Two-Step Forecast of Geomagnetic Storm Using Coronal Mass Ejection and Solar Wind Condition

    NASA Technical Reports Server (NTRS)

    Kim, R.-S.; Moon, Y.-J.; Gopalswamy, N.; Park, Y.-D.; Kim, Y.-H.

    2014-01-01

    To forecast geomagnetic storms, we had examined initially observed parameters of coronal mass ejections (CMEs) and introduced an empirical storm forecast model in a previous study. Now we suggest a two-step forecast considering not only CME parameters observed in the solar vicinity but also solar wind conditions near Earth to improve the forecast capability. We consider the empirical solar wind criteria derived in this study (Bz = -5 nT or Ey = 3 mV/m for t = 2 h for moderate storms with minimum Dst less than -50 nT) (i.e. Magnetic Field Magnitude, B (sub z) less than or equal to -5 nanoTeslas or duskward Electrical Field, E (sub y) greater than or equal to 3 millivolts per meter for time greater than or equal to 2 hours for moderate storms with Minimum Disturbance Storm Time, Dst less than -50 nanoTeslas) and a Dst model developed by Temerin and Li (2002, 2006) (TL [i.e. Temerin Li] model). Using 55 CME-Dst pairs during 1997 to 2003, our solar wind criteria produce slightly better forecasts for 31 storm events (90 percent) than the forecasts based on the TL model (87 percent). However, the latter produces better forecasts for 24 nonstorm events (88 percent), while the former correctly forecasts only 71 percent of them. We then performed the two-step forecast. The results are as follows: (i) for 15 events that are incorrectly forecasted using CME parameters, 12 cases (80 percent) can be properly predicted based on solar wind conditions; (ii) if we forecast a storm when both CME and solar wind conditions are satisfied (n, i.e. cap operator - the intersection set that is comprised of all the elements that are common to both), the critical success index becomes higher than that from the forecast using CME parameters alone, however, only 25 storm events (81 percent) are correctly forecasted; and (iii) if we forecast a storm when either set of these conditions is satisfied (?, i.e. cup operator - the union set that is comprised of all the elements of either or both

  16. Strength of the Archean geomagnetic field and effectiveness of magnetic shielding from the young active Sun

    NASA Astrophysics Data System (ADS)

    Tarduno, J. A.

    2008-05-01

    The strength of Earth's early magnetic field is important for understanding the evolution of the core, surface environment, atmosphere and life. Paleointensity analyses of single silicate crystals indicate that the strength of the geomagnetic field 3.2 billion years ago was within 50% of the modern value (Tarduno et al., 2007), but for even earlier times it is unknown. Two ideas have been offered: (1) the geomagnetic field started shortly after core formation, and the subsequent field strength has been within a factor of 2-3 of the modern value since its initiation; (2) the field was at null values ~3.9 billion years ago and commenced thereafter. The latter scenario relies on a hypothesis to explain the amount and isotopic composition of nitrogen found in soils of the Moon; this lunar nitrogen may have been derived from Earth's atmosphere via the solar wind (Ozima et al., 2005) in the absence of geomagnetic field that would otherwise shield atmospheric erosion. The possibility of a delayed dynamo onset (Labrosse et al., 2007) will be discussed, as will our efforts to address the presence/absence of the geomagnetic field between 3.2 and 3.9 billion years ago using the terrestrial rock record. The available constraints on ancient magnetic shielding will be reviewed in light of the radiation and particle flux associated with the active young Sun. (References: Labrosse et al., A crystallizing dense magma ocean at the base of the Earth's mantle, Nature, 450, 866-868, 2007; Ozima, M., et al., Terrestrial nitrogen and noble gases in lunar soils, Nature, 436, 655-659, 2005; Tarduno, J.A. et al., Geomagnetic field strength 3.2 billion years ago recorded by single silicate crystals, Nature, 446, 657-660, 2007.)

  17. Statistical correlation of low-altitude ENA emissions with geomagnetic activity from IMAGE/MENA observations

    NASA Astrophysics Data System (ADS)

    Mackler, D. A.; Jahn, J.-M.; Perez, J. D.; Pollock, C. J.; Valek, P. W.

    2016-03-01

    Plasma sheet particles transported Earthward during times of active magnetospheric convection can interact with exospheric/thermospheric neutrals through charge exchange. The resulting Energetic Neutral Atoms (ENAs) are free to leave the influence of the magnetosphere and can be remotely detected. ENAs associated with low-altitude (300-800 km) ion precipitation in the high-latitude atmosphere/ionosphere are termed low-altitude emissions (LAEs). Remotely observed LAEs are highly nonisotropic in velocity space such that the pitch angle distribution at the time of charge exchange is near 90°. The Geomagnetic Emission Cone of LAEs can be mapped spatially, showing where proton energy is deposited during times of varying geomagnetic activity. In this study we present a statistical look at the correlation between LAE flux (intensity and location) and geomagnetic activity. The LAE data are from the MENA imager on the IMAGE satellite over the declining phase of solar cycle 23 (2000-2005). The SYM-H, AE, and Kp indices are used to describe geomagnetic activity. The goal of the study is to evaluate properties of LAEs in ENA images and determine if those images can be used to infer properties of ion precipitation. Results indicate a general positive correlation to LAE flux for all three indices, with the SYM-H showing the greatest sensitivity. The magnetic local time distribution of LAEs is centered about midnight and spreads with increasing activity. The invariant latitude for all indices has a slightly negative correlation. The combined results indicate LAE behavior similar to that of ion precipitation.

  18. Reaction of physiological factors on the solar-geomagnetic activity (the physical mechanisms)

    NASA Astrophysics Data System (ADS)

    Avakyan, Sergey; Voronin, Nikolai; Dubarenko, Konstantin

    , combined consideration of geo-electromagnetic radiation with carrier microwave frequency whose amplitude is modulated with the low-frequency (informational) component, is very promising. Indeed, in the Earth ionosphere the Schumann resonator is located between the Earth’s surface and the ionosphere region at the heights of 100 to 150 km (under Е-layer), while the Alfven resonator is substantially larger and occupies the entire F-region of the ionosphere, up to its upper part at the heights roughly 1000 km above the surface. Since virtually all characteristics of the ionosphere medium are specified by solar activity (and also by geomagnetic activity - at high latitudes, and even, in the case of the principal magnetic storms, at middle latitudes), the parameters of both resonators, in particular, such as the functional frequencies and Q-factor, reflect the current level of the activities, including their most powerful manifestations in cosmic weather perturbations: solar flares and geomagnetic storms. The experimental data related to helio-geo-biocorrelations indicate that the impact of solar flares, and, which is more important, of magnetic storms on patients with cardiovascular and cerebral circulation pathology is based on the increase of the blood viscosity under the influence of the amplified microwave radiation of the ionosphere, immunodisfunction develops due to deterioration of the quality of leukocytes under the same conditions as above, and the excitatory system is affected with microwave resonance at the frequencies of VLF - ELF amplitude modulation in Schumann (at frequencies above 7 Hz) and Alfven (at frequencies below 6 Hz and down to minor fractions of a Hertz) bands, which are close to basic rhythms of human brain. Indeed, these resonators display a set of basic frequencies: 6 - 7 to 40 Hz (Schumann’s) and 0,1 to 6 Hz (Alfven’s). In the first case, the resonance frequencies (roughly equal to 7.7, 13.8, 19.7, and 26.7 Hz) are consistent with Alpha, Beta

  19. On the high correlation between long-term averages of solar wind speed and geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Crooker, N. U.; Feynman, J.; Gosling, J. T.

    1977-01-01

    Six-month and yearly averages of solar-wind speed from 1962 to 1975 are shown to be highly correlated with geomagnetic activity as measured by averages of the Ap index. On the same time scale the correlation between the southward component of the interplanetary magnetic field and geomagnetic activity is poor. Previous studies with hourly averages gave opposite results. The better correlation with the southward component on an hourly time scale is explained by its large variation compared with the relatively constant solar-wind speed. However, on a yearly time scale the magnitude of the variations in both parameters are about the same. This problem can be solved by invoking an energy transfer mechanism which is proportional to the first power of the southward component and a higher power of the solar-wind speed.

  20. [A comprehensive analysis of incidence of myocardial infarction in Vladikavkaz depending on solar and geomagnetic activity].

    PubMed

    Botoeva, N K; Khetarugova, l G; Rapoport, S I

    2013-01-01

    The data on myocardial infarction morbidity in Vladikavkaz for 2007-2010 were analysed with reference to solar and geomagnetic activity. Time series of morbidity in men and women were constructed and their seasonal constituent was distinguished. It was found that the number of myocardial infarctions increases on day with enhanced geomagnetic activity especially among subjects aged 50-69 years. Regression analysis of the relationship between the number of sunspots and myocardial infarctions yielded the equation of piecewise linear regression showing that 42% of the cases were due to the changes in the number of sunspots. Medium strength negative correlation was found between the number of myocardial infarctions and the recurrence index of Bz-component of the interplanetary magnetic field. It suggests an important role of chaotic dynamics of external factors in the development of myocardial infarction. PMID:25696947

  1. Geomagnetic activity during 10 - 11 solar cycles that has been observed by old Russian observatories.

    NASA Astrophysics Data System (ADS)

    Seredyn, Tomasz; Wysokinski, Arkadiusz; Kobylinski, Zbigniew; Bialy, Jerzy

    2016-07-01

    A good knowledge of solar-terrestrial relations during past solar activity cycles could give the appropriate tools for a correct space weather forecast. The paper focuses on the analysis of the historical collections of the ground based magnetic observations and their operational indices from the period of two sunspot solar cycles 10 - 11, period 1856 - 1878 (Bartels rotations 324 - 635). We use hourly observations of H and D geomagnetic field components registered at Russian stations: St. Petersburg - Pavlovsk, Barnaul, Ekaterinburg, Nertshinsk, Sitka, and compare them to the data obtained from the Helsinki observatory. We compare directly these records and also calculated from the data of the every above mentioned station IHV indices introduced by Svalgaard (2003), which have been used for further comparisons in epochs of assumed different polarity of the heliospheric magnetic field. We used also local index C9 derived by Zosimovich (1981) from St. Petersburg - Pavlovsk data. Solar activity is represented by sunspot numbers. The correlative and continuous wavelet analyses are applied for estimation of the correctness of records from different magnetic stations. We have specially regard to magnetic storms in the investigated period and the special Carrington event of 1-2 Sep 1859. Generally studied magnetic time series correctly show variability of the geomagnetic activity. Geomagnetic activity presents some delay in relation to solar one as it is seen especially during descending and minimum phase of the even 11-year cycle. This pattern looks similarly in the case of 16 - 17 solar cycles.

  2. Geomagnetic activity that corresponds to the median of the F2-layer critical frequency at various latitudes

    NASA Astrophysics Data System (ADS)

    Deminov, M. G.; Deminova, G. F.

    2016-09-01

    On the basis of the F2-layer critical frequency foF2 for the noon at some European stations for 1958-2005, it is found that the geomagnetic activity corresponding to the foF2 median is systematically lower than that averaged over the month; the difference increases with an increase in latitude. Moreover, the dispersion of geomagnetic activity for the foF2 median at relatively high latitudes is lower than at middle latitudes. These regularities are related to the fact that high geomagnetic activity usually leads to a distinct deviation of foF2 from the typical average value, i.e., from the foF2 median, and such deviation is more substantial at relatively high latitudes. That is why the geomagnetic activity for the foF2 median is lower at relatively high latitudes than at middle latitudes.

  3. Empirical regional models for the short-term forecast of M3000F2 during not quiet geomagnetic conditions over Europe

    NASA Astrophysics Data System (ADS)

    Pietrella, Marco

    An empirical regional model for the prediction of the monthly median field of M3000F2 over Europe (indicated as RM_M3000F2) was developed. Thanks to the IFELM_foF2 models, that are able to provide short-term forecasts of the critical frequency of the F2 layer (foF2 _{STF}) up to three hours in advance, it was possible to considerer the Brudley-Dudeney algorithm as a function of foF2 _{STF} to correct RM_M3000F2 and thus obtaining an empirical regional model for the short-term forecasting of M3000F2 (indicated as RM_M3000F2_BD) up to three hours in advance under not quiet geomagnetic conditions. From the long-term predictions of M3000F2 provided by the IRI model, an empirical regional model for the forecast of the monthly median field of M3000F2 over Europe (indicated as IRI_RM_M3000F2) was derived. IRI_RM_M3000F2 predictions were modified with the Bradley-Dudeney correction factor and another empirical regional model for the short-term forecasting of M3000F2 (indicated as IRI_RM_M3000F2_BD) up to three hours ahead under not quiet geomagnetic conditions was obtained. The main results achieved comparing the performance of RM_M3000F2, RM_M3000F2_BD, IRI_RM_M3000F2, and IRI_RM_M3000F2_BD are: (1) in case of moderate geomagnetic activity, the Bradley-Dudeney correction factor does not improve significantly the predictions; 2) under disturbed geomagnetic conditions, the Bradley-Dudeney formula improves the predictions of RM_M3000F2 in all the European area; (3) in case of very disturbed geomagnetic conditions, Bradley-Dudeney algorithm is very effective in improving the performance of IRI_RM_M3000F2; (4) the forecasting maps originated by RM_M3000F2, RM_M3000F2_BD, and IRI_RM_M3000F2_BD, show some regions where the forecasts are not satisfactory, but also wide sectors where the M3000F2 forecasts quite faithfully match the M3000F2 observations, and therefore the proposed models could be exploited to produce short-term forecasting maps of M3000F2 over Europe up to 3 hours

  4. Prediction of geomagnetic activity on time scales of one to ten years

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Gu, X. Y.

    1986-01-01

    The long-term prediction of geomagnetic indices that characterize the state of the magnetosphere is discussed. While a prediction of the yearly average sunspot number is simultaneously a prediction of the yearly number of sudden-commencement storms, it is not a prediction of the number of disturbed or quiet half days. Knowledge of the sunspot cycle phase leads to a good estimate of the correlation expected between activity during one 27-day solar rotation period and the next.

  5. Spectral Structure of Pc1 Geomagnetic Pulsations under Magnetically Quiet and Disturbed Conditions

    NASA Astrophysics Data System (ADS)

    Feygin, F. Z.; Khabazin, Yu. G.; Kleimenova, N. G.; Malysheva, L. M.

    2016-05-01

    The analysis of geomagnetic Pc1 pulsations recorded in 2006-2010 at the Scandinavian network of the induction magnetometers has been performed. It was found that the spectral structure of Pc1 pulsations was different under the quiet and disturbed magnetic conditions. Analysis of these data showed that in magnetically quiet conditions (Kp ~0-1), in more than 90% of cases, Pc1 pulsations were observed in a narrow frequency band of around 0.2-0.4 Hz with the central oscillation frequency in the series (wave packets) of ~ 0.5-0.7 Hz. Under the disturbed conditions (Kp ~ 2-3), the central frequency of Pc1 waves became almost twice greater (~ 1.0-1.2 Hz) and the spectral width increased up to ~ 0.5-0.7 Hz. The relation of the frequency spectrum width of Pc1 pulsations with magnetospheric parameters was theoretically studied. An analytical expression was obtained and the numerical calculations have been performed. The performed theoretical calculations showed that the evolution of the frequency width of the dynamic spectrum of the Pc1 wave packets depends on the magnetosphere plasma parameters. It was found that the Pc1 spectral width increases with decreasing of the proton thermal anisotropy. We suppose that under quiet conditions, the Pc1 generation can take place inside the plasmasphere but near the plasmapause located at higher L there were small VA values. During the disturbed periods, the Pc1 generation can take place outside the plasmasphere at lower L there were high VA values.

  6. Geomagnetic Activity Forecasting Using Self-Learning Algorithms: Application in Space Weather Studies

    NASA Astrophysics Data System (ADS)

    Khalil, A. F.; Barakat, A. R.; McKee, M.

    2005-05-01

    The ability to forecast the geomagnetic activities is becoming more important as human activity in space becomes more prevalent. For example, early warning of geomagnetic storms could help mitigate their harmful effects on space electronics and on electrical power lines. Moreover, recently developed space weather algorithms that utilize physics-based models require future values of Kp as an input in order to forecast the ionospheric behavior. Computational learning theory and data-driven modeling techniques are new and rapidly expanding areas of research that aim at developing efficient learning algorithms. Here we compare self-learning algorithms regarding their abilities to forecast the level of geomagnetic activities, as represented by Kp. In particular, we consider the following algorithms: artificial neural networks, locally weighted projection regression, support vector machines, and relevance vector machines. Different parameters are considered such as: (1) length of forecasting time, (2) type and size of input data, and (3) training set size. These learning machines are compared regarding their generalization capabilities and structure reliabilities. The relative strengths and limitations of these algorithms will be presented.

  7. The effect of variations of geomagnetic activity changing rate on trunk objects

    NASA Astrophysics Data System (ADS)

    Kozlov, V. I.; Mullayarov, V. A.; Grigor'ev, Yu. M.

    2015-11-01

    The frequency of occurrence of a certain level of the rate of change of geomagnetic activity can be expressed as a power law with an exponent of the order -1.7, and the probability of exceedance of a given level can be expressed by the law lg(P) = -0.0517 (dB / dt) - 0.1946. The largest high-frequency variations are noted during the recovery phase of magnetic bay and correspond to geomagnetic pulsations of the Pc5 range (a period of variations of 200-300 s). On a pipeline on these pulsations other high-frequency variations are imposed and they start earlier - from a maximum of bay of disturbance. It is noted the need of monitoring and forecasting of magnetic storms and recommendations on the allocation of periods, during which one cannot disable protection for preventive works.

  8. Lower thermosphere (80-100 km) dynamics response to solar and geomagnetic activity: Overview

    NASA Technical Reports Server (NTRS)

    Kazimirovsky, E. S.

    1989-01-01

    The variations of solar and geomagnetic activity may affect the thermosphere circulation via plasma heating and electric fields, especially at high latitudes. The possibility exists that the energy involved in auroral and magnetic storms can produce significant changes of mesosphere and lower thermosphere wind systems. A study of global radar measurements of winds at 80 to 100 km region revealed the short term effects (correlation between wind field and geomagnetic storms) and long term variations over a solar cycle. It seems likely that the correlation results from a modification of planetary waves and tides propagated from below, thus altering the dynamical regime of the thermosphere. Sometimes the long term behavior points rather to a climatic variation with the internal atmospheric cause than to a direct solar control.

  9. Dependence of Characteristics of SURA Induced Artificial ULF/VLF Signals on Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Kotik, D. S.; Ryabov, A. V.; Ermakova, E. N.; Pershin, A. V.

    2015-10-01

    A comprehensive study of artificial ionospheric signal generation in the ULF/VLF bands at SURA facility in Russia was conducted during the past 4 years. We investigated the influence of geomagnetic activity on the characteristics of artificial low-frequency signals under the background of increasing solar activity. No correlation of artificial ULF signals with variations of Earth's magnetic field was observed for weak geomagnetic disturbances (Kp ≤ 3) while the VLF signals increased in the growth phase of the geomagnetic perturbation. In case of strong magnetic storm (Kp ≥ 5+) a tendency of the amplitude of the ULF/VLF signals decrease with increasing magnetic disturbance was observed. Sometimes, the modulation of artificial ULF signals with a period of 15-30 s was detected in the decay phase of magnetic storms. During storm time, a change in the polarization of artificial VLF emissions was detected. The right polarization becomes predominant. Interpretation of observed peculiarities of artificial VLF signals is given in the context of the physical mechanism of ionospheric current drive by RF pumping.

  10. Associations of geomagnetic activity with plasma sheet thinning and expansion: A statistical study

    SciTech Connect

    Hones,Jr., E.W.; Pytte, T.; West,Jr., H.I.

    1984-07-01

    Associations of geomagnetic activity in the auroral zone with thinnings and expansions of the magnetotail plasma sheet are examined statistically in this paper. We first identified many plasma sheet thinnings and expansions in plasma and particle data from VELA satellites and from OGO 5 without reference to the ground magnetic data. These events were grouped according to the location of the detecting satellite in the magnetotail. For each such group the times of thinning or expansion were then used as fiducial times in a superposed-epoch analysis of the geomagnetic AL index values that were recorded in 8-hour intervals centered on the event times. The results show that many plasma sheet thinnings and expansions are related to discrete negative bay structures that are the classical signature of substorms. Furthermore, they support earlier findings that plasma sheet thinning and expansion at the VELA orbit (rroughly-equal18 R/sub E/) tend to be associated with the onset of the auroral zone negative bay and the beginning of its subsidence, respectively. Earthward of rroughly-equal13-15 R/sub E/, plasma sheet expansion occurs near the time of the onset of the negative bay, again in agreement with earlier findings. A large fraction of plasma sheet expansions to half thicknesses of > or approx. =6 R/sub E/ at the VELA orbit are associated not with a baylike geomagnetic disturbance but with subsidence of a prolonged interval of disturbance. The study also shows that many plasma sheet expansions are related simply to generally enhanced geomagnetic activity showing no baylike or other distinctive features.

  11. Statistical study of interplanetary condition influence on the geomagnetic substorm onset location inferred from SuperMAG auroral electrojet indices

    NASA Astrophysics Data System (ADS)

    Huang, Sheng; Du, Aimin; Cao, Xin

    2015-04-01

    It is well known that the magnetospheric substorm occurs every few hours, in response with the interplanetary condition variation and the increase of energy transfer from the solar wind to the magnetosphere. Since the substorm activity correlated well with the geomagnetic index, Newell and Gjerloev [2011] identified the substorm onset and its contributing station, using the SuperMag auroral electrojet indices. In this study, we investigate the distribution of these substorm onset locations and its response to the varied interplanetary condition. It is surprise that the substorm onset locations show double-peak structure with one peak around pre-midnight sector and the other at the dawn side. The substorm onset tends to occur in pre-midnight sector during non-storm time while it often takes place in late morning sector (~4 MLT) during storm time. Furthermore, substorms, appearing in magnetic storm main phase predominate in late morning. As the geomagnetic index Dst decreases, the substorm onset occurs in late morning more frequently. The substorm onset locations were also classified based on the solar wind parameters. It is shown that the peak number ratio of the substorm onset location in late morning over pre-midnight increases as IMF Bz decreases from positive to negative and the solar wind velocity Vsw enhances. The more intense interplanetary electric field E promotes the substorm onset occurring in late morning. It is widely accepted that both the directly driven (DD) and loading/unloading (LL/UL) processes play an essential role in the energy dispensation from the solar wind into the magnetosphere-ionosphere system. In general, the former one corresponds to the DP2 current system, which consists of the eastward electrojet centered near the dusk and the westward electrojet centered in the dawn, while the latter one corresponds to the DP1 current system, which is dominated by the westward electrojet in the midnight sector. Our statistical results of substorm

  12. Substorms observations during two geomagnetically active periods in March 2012 and March 2015

    NASA Astrophysics Data System (ADS)

    Guineva, V.; Despirak, I.; Kozelov, B.

    2016-05-01

    In this work two events of strong geomagnetic activity were examined: the period 7-17 March 2012, which is one of the most disturbed periods during the ascending phase of Solar Cycle 24, and the severe geomagnetic storm on 17-20 March 2015. During the first period four consecutive magnetic storms occurred on 7, 9, 12, and 15 March. These storms were caused by Sheath, MC and HSS, and the detailed scenarios for the storms were different. The second event is a storm of fourth level with Kp = 8, the strongest one during the last four years, the so-called "St. Patrick's Day 2015 Event". A geomagnetic storm of such intensity was observed in September 2011. Our analysis was based on the 10-s sampled IMAGE magnetometers data, the 1-min sampled OMNI solar wind and interplanetary magnetic field (IMF) data and observations of the Multiscale Aurora Imaging Network (MAIN) in Apatity. The particularities in the behaviours of substorms connected with different storms during these two interesting strongly disturbed periods are discussed.

  13. Ionospheric data assimilation with thermosphere-ionosphere-electrodynamics general circulation model and GPS-TEC during geomagnetic storm conditions

    NASA Astrophysics Data System (ADS)

    Chen, C. H.; Lin, C. H.; Matsuo, T.; Chen, W. H.; Lee, I. T.; Liu, J. Y.; Lin, J. T.; Hsu, C. T.

    2016-06-01

    The main purpose of this paper is to investigate the effects of rapid assimilation-forecast cycling on the performance of ionospheric data assimilation during geomagnetic storm conditions. An ensemble Kalman filter software developed by the National Center for Atmospheric Research (NCAR), called Data Assimilation Research Testbed, is applied to assimilate ground-based GPS total electron content (TEC) observations into a theoretical numerical model of the thermosphere and ionosphere (NCAR thermosphere-ionosphere-electrodynamics general circulation model) during the 26 September 2011 geomagnetic storm period. Effects of various assimilation-forecast cycle lengths: 60, 30, and 10 min on the ionospheric forecast are examined by using the global root-mean-squared observation-minus-forecast (OmF) TEC residuals. Substantial reduction in the global OmF for the 10 min assimilation-forecast cycling suggests that a rapid cycling ionospheric data assimilation system can greatly improve the quality of the model forecast during geomagnetic storm conditions. Furthermore, updating the thermospheric state variables in the coupled thermosphere-ionosphere forecast model in the assimilation step is an important factor in improving the trajectory of model forecasting. The shorter assimilation-forecast cycling (10 min in this paper) helps to restrain unrealistic model error growth during the forecast step due to the imbalance among model state variables resulting from an inadequate state update, which in turn leads to a greater forecast accuracy.

  14. Diurnal changes of earthquake activity and geomagnetic Sq-variations

    NASA Astrophysics Data System (ADS)

    Duma, G.; Ruzhin, Y.

    Statistic analyses demonstrate that the probability of earthquake occurrence in many earthquake regions strongly depends on the time of day, that is on Local Time (e.g. Conrad, 1909, 1932; Shimshoni, 1971; Duma, 1997; Duma and Vilardo, 1998). This also applies to strong earthquake activity. Moreover, recent observations reveal an involvement of the regular diurnal variations of the Earth's magnetic field, commonly known as Sq-variations, in this geodynamic process of changing earthquake activity with the time of day (Duma, 1996, 1999). In the article it is attempted to quantify the forces which result from the interaction between the induced Sq-variation currents in the Earth's lithosphere and the regional Earth's magnetic field, in order to assess the influence on the tectonic stress field and on seismic activity. A reliable model is obtained, which indicates a high energy involved in this process. The effect of Sq-induction is compared with the results of the large scale electromagnetic experiment "Khibiny" (Velikhov, 1989), where a giant artificial current loop was activated in the Barents Sea.

  15. Geomagnetic response to solar activity: summary for the last ten years and analysis of selected cases

    NASA Astrophysics Data System (ADS)

    Hejda, Pavel; Bochníček, Josef; Valach, Fridrich; Revallo, Miloš

    2014-05-01

    The main sources of geomagnetic disturbances are either coronal mass ejections (CMEs), which are usually connected with eruptive flares, or high-speed streams of solar wind from coronal holes. Development of an eruptive flare and ejection of coronal mass is accompanied by magnetic reconnection. The evidence of reconnection can be found in a broad spectrum of observations. The observations of X-rays and radio bursts were used in our study. The geoeffectiveness of solar X-ray flares was initially analysed on data from the period 1996 - 2004 [1]. It was shown that the probability of geomagnetic response depends on the solar flare class and its position on the solar disc. The flares in the central region were found to be more geoeffective. The probability further increased if the flare was accompanied by Type II and/or Type IV of solar radio bursts. In the next step a neural network model was developed to determine the probability, with which flares will be followed by the geomagnetic response of a particular intensity. Enhancement of solar energetic particle flux was added to the set of input parameters. The results indicated that X-ray flares accompanied by solar radio bursts represent a good proxy of CMEs [2, 3]. This conclusion was now confirmed by the data from the period 2005 - 2012. Coronal holes are stable formations that can survive over several solar rotations. Corotating interaction regions (CIRs) between fast and slow solar wind can thus periodically pass over the Earth and cause recurrent geomagnetic storms. This periodicity makes the forecasts of the geomagnetic disturbances much easier [4] than in the case of eruptive phenomena. Our analysis confirmed that the strongest magnetic storms are caused by CMEs. Nevertheless, many geomagnetic disturbances in the active part of solar cycle are influenced by sequences of CMEs and CIRs, which increase their strength. [1] Bochníček, J., P. Hejda and F. Valach, Solar energetic events in the years 1996-2004. The

  16. Quality of GOCE accelerometer data and analysis with ionospheric dynamics during geomagnetically active days

    NASA Astrophysics Data System (ADS)

    Sinem Ince, Elmas; Fomichev, Victor; Floberghagen, Rune; Schlicht, Anja; Martynenko, Oleg; Pagiatakis, Spiros

    2016-07-01

    The Gravity field and steady-state Ocean Circulation Explorer (GOCE) was launched in March, 2009 and completed its mission with great success in November, 2011. GOCE data processing is challenging and not all the disturbances are removed from the gravitational field observations. The disturbances observed in GOCE Vyy gradients around magnetic poles are investigated by using external datasets. It is found that the amplitude of these disturbances increase during geomagnetically active days and can reach up to 5 times the expected noise level of the gradiometer. ACE (Advanced Composition Explorer) and Wind satellites measured electric field and interplanetary magnetic field components have shown that the disturbances observed in the polar regions agree with the increased solar activity. Moreover, equivalent ionospheric currents computed along ascending satellite tracks over North America and Greenland have shown a noticeable correlation with the cross-track and vertical currents and the pointing flux (ExB) components in the satellite cross track direction. Lastly, Canadian Ionosphere and Atmosphere Model (C-IAM) electric field and neutral wind simulations have shown a strong correlation of the enhancement in the ionospheric dynamics during geomagnetically active days and disturbances measured by the GOCE accelerometers over high latitudes. This may be a result of imperfect instrumentation and in-flight calibration of the GOCE accelerometers for an increased geomagnetic activity or a real disturbance on the accelerometers. We use above listed external datasets to understand the causes of the disturbances observed in gravity gradients and reduce/ eliminate them by using response analyses in frequency domain. Based on our test transfer functions, improvement is possible in the quality of the gradients. Moreover, this research also confirms that the accelerometer measurements can be useful to understand the ionospheric dynamics and space weather forecasting.

  17. Clinical Cosmobiology - Sudden Cardiac Death and Daily / Monthly Geomagnetic, Cosmic Ray and Solar Activity - the Baku Study (2003-2005)

    NASA Astrophysics Data System (ADS)

    Stoupel, E.; Babayev, E. S.; Mustafa, F. R.; Abramson, E.; Israelevich, P.; Sulkes, J.

    2006-12-01

    Part of results of collaborative studies for revealing an influence of the periodical changes of solar, geomagnetic and cosmic ray activities on the sudden cardiac death (SCD) mortality is described in this paper. The data covering daily and monthly temporal distribution of SCD (788 patients in 36 months in 2003-2005), taken from all of emergency and first medical aid stations of grand Baku area, were analyzed and compared with certain cosmophysical parameters. It was obtained that SCD is higher on the highest and lowest daily levels of geomagnetic activity. Days with SCD are accompanied by higher cosmic ray (neutron) activity. The monthly number of SCD was inversely related to solar and geomagnetic activities while was positively linked with cosmic ray activity level. It was concluded that cosmic ray activity could be considered as one of regulating external/environmental factors in human homeostasis.

  18. Solar activity dependence of nightside aurora in winter conditions

    NASA Astrophysics Data System (ADS)

    Zhou, Su; Luan, Xiaoli; Dou, Xiankang

    2016-02-01

    The dependence of the nightside (21:00-03:00 MLT; magnetic local time) auroral energy flux on solar activity was quantitatively studied for winter/dark and geomagnetically quiet conditions. Using data combined from Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Global Ultraviolet Imager and Defense Meteorological Satellite Program/Special Sensor Ultraviolet Spectrographic Imager observations, we separated the effects of geomagnetic activity from those of solar flux on the nightside auroral precipitation. The results showed that the nightside auroral power was reduced by ~42% in solar maximum (F10.7 = 200 sfu; solar flux unit 1 sfu = 10-22 W m-2 Hz-1) with respect to that under solar minimum (F10.7 = 70 sfu) for the Kp = 1 condition, and this change rate became less (~21%) for the Kp = 3 condition. In addition, the solar cycle dependence of nightside auroral power was similar with that from both the premidnight (21:00-23:00 MLT) and postmidnight (01:00-03:00 MLT) sectors. These results indicated that as the ionospheric ionization increases with the enhanced auroral and geomagnetic activities, the solar activity dependences of nightside auroral power become weaker, at least under geomagnetically quiet conditions.

  19. Characteristics of upstream energetic (E>=50keV) ion events during intense geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Rigas, A. G.; Sarris, E. T.; Krimigis, S. M.

    1998-05-01

    In this work we examine the statistical presence of some important features of upstream energetic (>=50 keV) ion events under some special conditions in the upstream region and the magnetosphere. The 125 ion events considered in the statistic were observed by the IMP 7 and IMP 8 spacecraft, at ~35RE from the Earth, during nine long time intervals of a total of 153 hours. The time intervals analyzed were selected under the following restrictions: existence of high proton flux (i.e., >=900 pcm-2s-1sr-1) and of a great number of events (an occurrence frequency of ~10 events per 12 hours in the whole statistics) in the energy range 50-220 keV. The most striking findings are the following: (1) The upstream events were observed during times with high values of the geomagnetic activity index Kp(>=3-) (2) all of the upstream events (100%) have energy spectra extending up to energies E>=290keV (3) 86% of these events are accompanied by relativistic (E>=220keV) electrons; and (4) the majority of the upstream ion events (82%) showed noninverse velocity dispersion during their onset phase (22% of the events showed forward velocity dispersion, and 60% showed no velocity dispersion at all when 5.5-min averaged observations were analyzed). Further statistical analysis of this sample of upstream particle events shows that the 50- to 220-keV proton flux shows a positive correlation with the following parameters: the Kp index of geomagnetic activity and the flux of the high-energy (290-500 keV) protons and (>=220 keV) electrons. More specific findings are the following: (1) The spectral index γ for a power law distribution of ions detected by the National Oceanic and Atmospheric Administration Energetic Particle Experiment (EPE) instrument (50<=E<=220keV) and The Johns Hopkins University Applied Physics Laboratory Charged Particle Measurement Experiment (CPME) instrument (290<=E<=500keV) ranges between 2 and 6, with maximum probability between 4 and 5 and (2) the peak

  20. Evaluating space weather forecasts of geomagnetic activity from a user perspective

    NASA Astrophysics Data System (ADS)

    Thomson, A. W. P.

    2000-12-01

    Decision Theory can be used as a tool for discussing the relative costs of complacency and false alarms with users of space weather forecasts. We describe a new metric for the value of space weather forecasts, derived from Decision Theory. In particular we give equations for the level of accuracy that a forecast must exceed in order to be useful to a specific customer. The technique is illustrated by simplified example forecasts for global geomagnetic activity and for geophysical exploration and power grid management in the British Isles.

  1. The Formation of CIRs at Stream-Stream Interfaces and Resultant Geomagnetic Activity

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.

    2005-01-01

    Corotating interaction regions (CIRs) are regions of compressed plasma formed at the leading edges of corotating high-speed solar wind streams originating in coronal holes as they interact with the preceding slow solar wind. Although particularly prominent features of the solar wind during the declining and minimum phases of the 11-year solar cycle, they may also be present at times of higher solar activity. We describe how CIRs are formed, and their geomagnetic effects, which principally result from brief southward interplanetary magnetic field excursions associated with Alfven waves. Seasonal and long-term variations in these effects are briefly discussed.

  2. No covariation between the geomagnetic activity and the incidence of acute myocardial infarction in the polar area of northern Sweden.

    PubMed

    Messner, T; Häggström, I; Sandahl, I; Lundberg, V

    2002-05-01

    This study was undertaken to investigate whether there was any relation between the aurora borealis (measured as the geomagnetic activity) and the number of acute myocardial infarctions (AMI) in the northern, partly polar, area of Sweden. The AMI cases were collected from The Northern Sweden MONICA (multinational MONItoring of trends and determinants of CArdiovascular disease) AMI registry between 1985 and 1998, inclusive, and the information on the geomagnetic activity from continuous measurements at the Swedish Institute of Space Physics, Kiruna. In the analyses, both the relation between the individual AMI case and ambient geomagnetic activity, and the relation between the mean daily K index and the daily number of AMI cases were tested. We found no statistically significant relation between the number of fatal or non-fatal AMI cases, the number of sudden deaths or the number of patients with chest pain without myocardial damage, and geomagnetic activity. Our data do not support a relation between the geomagnetic activity and AMI. PMID:12135204

  3. Daytime additional F layer stratification over low-midlatitude station of the Indian sector under geomagnetic disturbed conditions

    NASA Astrophysics Data System (ADS)

    Yadav, Sneha; Upadhayaya, A. K.; Das, Rupesh M.

    2012-06-01

    In this paper, the observations of additional F layer stratification are presented in a region which is situated at the outer edge of equatorial ionization anomaly (EIA) zone. The digital ionosonde data observed over Delhi (28.6° N, 77.2° E, dip 42.44° N) during March-April, 2001 has been used to carry out the present work. The observational period was geomagnetically disturbed and represents the high solar activity phase of 23rd solar cycle. The additional transient cusp is frequently observed in the considered months before the noon hours; however, in this paper only five prominent cases are presented. From the analysis of ionograms, it is observed that the transient additional cusp is formed between the pre-existing F1 and F2 layer; hence, named as the cusp of F1.5. Study reveals that the Traveling Atmospheric Disturbances (TADs) along with the vertical expansion of F layer provides the necessary condition for the existence of this transient feature. The intensification of F1 layer along with increased altitude immediately after the disappearance of additional stratification remains one of the fascinating features of the present results. The present investigation demonstrates that the daytime F1 and F2 region over low-midlatitude station is strongly modulated by the passage of TIDs, originating at high latitudes or by atmospheric disturbances of local origin during the high solar activity period. The concurrent presence of TADs and the associated disturbance composition appears to be plausible reason behind the present observations.

  4. Locally linear neurofuzzy modeling and prediction of geomagnetic disturbances based on solar wind conditions

    NASA Astrophysics Data System (ADS)

    Sharifie, Javad; Lucas, Caro; Araabi, Babak N.

    2006-06-01

    Disturbance storm time index (Dst) is nonlinearly related to solar wind data. In this paper, Dst past values, Dst derivative, past values of southward interplanetary magnetic field, and the square root of dynamic pressure are used as inputs for modeling and prediction of the Dst index, especially during extreme events. The geoeffective solar wind parameters are selected depending on the physical background of the geomagnetic storm procedure and physical models. A locally linear neurofuzzy model with a progressive tree construction learning algorithm is applied as a powerful tool for nonlinear modeling of Dst index on the basis of its past values and solar wind parameters. The result for modeling and prediction of several intense storms shows that the geomagnetic disturbance Dst index based on geoeffective parameters is a nonlinear model that could be considered as the nonlinear extension of empirical linear physical models. The method is applied for prediction of some geomagnetic storms. Obtained results show that using the proposed method, the predicted values of several extreme storms are highly correlated with observed values. In addition, prediction of the main phase of many storms shows a good match with observed data, which constitutes an appropriate approach for solar storm alerting to vulnerable industries.

  5. Quantitative increases in temporal lobe symptoms in human males are proportional to postnatal geomagnetic activity: verification by canonical correlation.

    PubMed

    Hodge, K A; Persinger, M A

    1991-04-29

    Enhanced geomagnetic activity during episodes of biochemical stress has been correlated with inferences of increased liability within deep temporal lobe structures. Because adult limbic epilepsy is frequently associated with perinatal hypoxia or metabolic disruption within this region, a weak positive correlation was expected between possible signs of mesiobasal temporal lobe lability in normal adults and perinatal geomagnetic activity. Canonical correlation demonstrated that young adult males (n = 243) displayed a positive (r = 0.31) relationship between the intensity of geomagnetic disturbance the day after birth only and a history of subjective depersonalization, anomalous visual and olfactory experiences. The effects was very clear when aa values exceeded 30 nT (gamma). Temporal lobe signs for these males were similar to those reported by normal young adult females (n = 313) who did not display any consistent correlation between these measures and perinatal geomagnetic disturbance. The results suggest that interactions between perinatal neurochemistry and the correlates of geomagnetic activity might permanently alter portions of the male limbic system. PMID:1881599

  6. Forecasting the geomagnetic activity of the Dst index using multiscale radial basis function networks

    NASA Astrophysics Data System (ADS)

    Wei, H. L.; Zhu, D. Q.; Billings, S. A.; Balikhin, M. A.

    The Dst index is a key parameter which characterises the disturbance of the geomagnetic field in magnetic storms. Modelling of the Dst index is thus very important for the analysis of the geomagnetic field. A data-based modelling approach, aimed at obtaining efficient models from limited input-output observational data, provides a powerful tool for analysing and forecasting geomagnetic activities including the prediction of the Dst index. In this study, the process of the Dst index is treated to be a structure-unknown system, where the solar wind parameter ( VBs) and the solar wind dynamic pressure ( P) are the system inputs, and the Dst index is the system output. A novel multiscale RBF (MSRBF) network is introduced to represent such a two-input and single-output system, where the Dst index is related to the solar wind parameter and the dynamic pressure, via a hybrid network model consisting of two submodels: a linear part that reflects the linear relationship between the output and the inputs, and a nonlinear part that captures the effect of the interacting contribution of past observations of the inputs and the output, on the current output. The proposed MSRBF network can easily be converted into a linear-in-the-parameters form and the training of the linear network model can easily be implemented using a forward orthogonal regression (FOR) algorithm. One advantage of the new MSRBF network, compared with traditional single scale RBF networks, is that the new network is more flexible for describing complex nonlinear dynamical systems.

  7. A 22-yrs Hurricane Cycle and its Relation to Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Mendoza, Blanca; Pazos, Marni

    Applying spectral analysis to the Atlantic and Pacific hurricane time series, we found period-icities that coincide with the main sunspot and magnetic solar cycles. To assess the possibility that these periodicities could be associated to solar activity, we obtain correlations between hurricane occurrence and several solar activity-related phenomena, such as the total solar irra-diance, the cosmic ray flux and the Dst index of geomagnetic activity. Our results indicate that the highest significant correlations are found between the Atlantic and Pacific hurricanes and the Dst index. Most importantly, both oceans present the highest hurricane-Dst correlations during the ascending part of odd solar cycles and the descending phase of even solar cycles. This shows not only the existence of a 22yrs cycle but also the nature of such periodicity. Fur-thermore, we found that the Atlantic hurricanes behave differently from the Pacific hurricanes in relation to the solar activity-related disturbances considered.

  8. Aurora Activities Observed by SNPP VIIRS Day-Night Band during St. Patrick's Day, 2015 G4 Level Geomagnetic Storm

    NASA Astrophysics Data System (ADS)

    Liu, T. C.; Shao, X.; Cao, C.; Zhang, B.; Fung, S. F.; Sharma, S.

    2015-12-01

    A G4 level (severe) geomagnetic storm occurred on March 17 (St. Patrick's Day), 2015 and it is among the strongest geomagnetic storms of the current solar cycle (Solar Cycle 24). The storm is identified as due to the Coronal Mass Ejections (CMEs) which erupted on March 15 from Region 2297 of solar surface. During this event, the geomagnetic storm index Dst reached -223 nT and the geomagnetic aurora electrojet (AE) index increased and reached as high as >2200 nT with large amplitude fluctuations. Aurora occurred in both hemispheres. Ground auroral sightings were reported from Michigan to Alaska and as far south as southern Colorado. The Day Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advancement in night time imaging capabilities. The DNB senses radiance that can span 7 orders of magnitude in one panchromatic (0.5-0.9 μm) reflective solar band and provides imagery of clouds and other Earth features over illumination levels ranging from full sunlight to quarter moon. In this paper, DNB observations of aurora activities during the St. Patrick's Day geomagnetic storm are analyzed. Aurora are observed to evolve with salient features by DNB for orbital pass on the night side (~local time 1:30am) in both hemispheres. The radiance data from DNB observation are collected at the night sides of southern and northern hemispheres and geo-located onto geomagnetic local time (MLT) coordinates. Regions of aurora during each orbital pass are identified through image processing by contouring radiance values and excluding regions with stray light near day-night terminator. The evolution of aurora are characterized with time series of the poleward and low latitude boundary of aurora, their latitude-span and area, peak radiance and total light emission of the aurora region in DNB observation. These characteristic parameters are correlated with solar wind and geomagnetic index parameters.

  9. The Effect of Helio-Geomagnetic Activity on the Proceedings in the Emergency Department of Two Greek Hospitals

    NASA Astrophysics Data System (ADS)

    Preka-Papadema, P.; Moussas, X.; Noula, M.; Katranitsa, H.; Theodoropoulou, A.; Katsavrias, Ch.; Vasiliou, Ch.; Kontogeorgou, E.; Tsaliki, S.-M.; Kailas, K.; Papadima, Th.

    2010-01-01

    Study of the solar and geomagnetic activity influence on the emergency proceedings in Greece, for selected months of solar cycle 23 and especially for the year 2005 is presented. We examined the time association between the magnetic storms (Dst geomagnetic index), daily numbers of solar flares and Coronal Mass Ejections (CMEs) with the emergency proceedings. The sample of about 30000 cases from two Greek hospitals (The General Hospital of the town of Lamia and The General Hospital of the town of Veria) analyzed according to diagnoses. The cardiological, neurological, accidents (multitrauma and burns) and oncological patients as well as in partially pathological/surgical patients showed an increase during periods of high helio-geomagnetic activity. In order to strengthen this result, more data need to be collected and analyzed.

  10. Associations by signatures and coherences between the human circulation and helio- and geomagnetic activity.

    PubMed

    Watanabe, Y; Cornélissen, G; Halberg, F; Otsuka, K; Ohkawa, S I

    2001-01-01

    Helio-geomagnetic influences on the human circulation are investigated on the basis of an 11-year-long record from a clinically healthy cardiologist, 35 years of age at the start of monitoring. He measured his blood pressure and heart rate around the clock with an ambulatory monitor programmed to inflate an arm cuff, mostly at intervals of 15-30 minutes, with only few interruptions, starting in August 1987. While monitoring is continuing, data collected up to July 1998 are analyzed herein by cosinor rhythmometry and cross-spectral coherence with matching records of solar activity, gauged by Wolf numbers (WN) and of the geomagnetic disturbance index, Kp. A direct association between heart rate (HR) and WN is found to be solar cycle stage-dependent, whereas an inverse relationship between heart rate variability (HRV) and WN is found consistently. An inverse relation is also observed between WN and the variability in systolic blood pressure (SBP), and to a lesser extent, diastolic blood pressure (DBP). Moreover, HR is cross-spectrally coherent with WN at a frequency of one cycle in about 7.33 months. The results support previously reported associations on morbidity and mortality statistics, extending their scope to human physiology monitored longitudinally. PMID:11774871

  11. Simulated sudden increase in geomagnetic activity and its effect on heart rate variability: Experimental verification of correlation studies.

    PubMed

    Caswell, Joseph M; Singh, Manraj; Persinger, Michael A

    2016-08-01

    Previous research investigating the potential influence of geomagnetic factors on human cardiovascular state has tended to converge upon similar inferences although the results remain relatively controversial. Furthermore, previous findings have remained essentially correlational without accompanying experimental verification. An exception to this was noted for human brain activity in a previous study employing experimental simulation of sudden geomagnetic impulses in order to assess correlational results that had demonstrated a relationship between geomagnetic perturbations and neuroelectrical parameters. The present study employed the same equipment in a similar procedure in order to validate previous findings of a geomagnetic-cardiovascular dynamic with electrocardiography and heart rate variability measures. Results indicated that potential magnetic field effects on frequency components of heart rate variability tended to overlap with previous correlational studies where low frequency power and the ratio between low and high frequency components of heart rate variability appeared affected. In the present study, a significant increase in these particular parameters was noted during geomagnetic simulation compared to baseline recordings. PMID:27662787

  12. Simulated sudden increase in geomagnetic activity and its effect on heart rate variability: Experimental verification of correlation studies

    NASA Astrophysics Data System (ADS)

    Caswell, Joseph M.; Singh, Manraj; Persinger, Michael A.

    2016-08-01

    Previous research investigating the potential influence of geomagnetic factors on human cardiovascular state has tended to converge upon similar inferences although the results remain relatively controversial. Furthermore, previous findings have remained essentially correlational without accompanying experimental verification. An exception to this was noted for human brain activity in a previous study employing experimental simulation of sudden geomagnetic impulses in order to assess correlational results that had demonstrated a relationship between geomagnetic perturbations and neuroelectrical parameters. The present study employed the same equipment in a similar procedure in order to validate previous findings of a geomagnetic-cardiovascular dynamic with electrocardiography and heart rate variability measures. Results indicated that potential magnetic field effects on frequency components of heart rate variability tended to overlap with previous correlational studies where low frequency power and the ratio between low and high frequency components of heart rate variability appeared affected. In the present study, a significant increase in these particular parameters was noted during geomagnetic simulation compared to baseline recordings.

  13. Contributions from geomagnetic inverse theory to the study of hydromagnetic conditions near the core-mantle boundary

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1991-01-01

    The Final Report on contributions from geomagnetic inverse theory to the study of hydromagnetic conditions near the core-mantle boundary (CMB) is presented. The original proposal was to study five questions concerning what the surface and satellite magnetic data imply about hydromagnetic and electromagnetic conditions near the CMB. The five questions are: (1) what do the surface and satellite data imply about the geomagnetic field B near the surface of the earth; (2) how does one extrapolate B down through the conducting mantle to the CMB; (3) if B on the CMB is visible, how accurately does it satisfy the frozen-flux approximation; (4) if frozen flux is a good approximation on the CMB, what can be inferred about the fluid velocity v in the upper core; and (5) if v at the CMB is visible, does it suggest any dynamical properties of the core, such as vertical advection, Alfven-inertial waves, link instabilities, or mantle effects. A summary of the research is provided.

  14. High energy ions and electrons upstream from the Earth's bow shock and their dependence on geomagnetic conditions: Statistical results between years 1982-1988

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Kaliabetsos, G.; Argyropoulos, G.; Sarris, E. T.

    We present initial results from a statistical analysis of 2034 energetic (50-220 keV) ion events observed by the IMP-8 spacecraft upstream from the Earth’s bow shock during a 6 years period. The most important findings are the following: (1) the percentage Pe of high intensity energetic ion events accompanied by the presence of relativistic (≥ 220 keV) electrons is ˜80% (for all geomagnetic conditions), and increases significantly with increasing the index Kp of geomagnetic activity, (2) high intensity energetic ion events most often (˜93%) show spectra extending up to energies E>˜300 keV, (3) a percentage of ˜71.5% of events display non-inverse energy dispersion of ion intensities. The above results, as well as additional results discussed in the text, suggest that a percentage as high as ˜80% of high intensity 50-220 keV ion events in our statistical sample have an origin within the magnetosphere.

  15. The role of solar and geomagnetic activity in the changes of the climatic characteristics of troposphere

    NASA Astrophysics Data System (ADS)

    Zherebtsov, Gelii; Rubtsova, Olga; Kovalenko, Vladimir; Molodykh, Sergey

    The main points of the model of the solar activity effect on the Earth climatic system are presented. The key concept of the model is heliogeophysical disturbance effect on the Earth climatic system parameters, which control energy flux, going from the Earth to the space, in high-latitude areas. The model is based on the physical mechanism of heliogeophysical factors' influence on climatic characteristics and atmospheric circulation in the high-latitude troposphere through the atmospheric electricity. In accordance with this mechanism, the at-mospheric electricity parameters in the high latitudes depend on the solar activity; at the same time, they influence the altitude distribution of charged condensation nuclei in the tropo-sphere, as well as the cloudiness formation and radiation balance and atmospheric circulation. NCEP/NCAR Reanalysis and CMAP data were used to analyze particularities and regularities of long-term variations in amount of precipitation in 1950-2007. Global decrease in amount of precipitation was found to dominate till late 1990s. It started increasing only 10 years ago. Peculiarities of distribution and long-term variations in amount of precipitation in different latitudes and longitudes were also considered. Correlation analysis of connection between the amount of precipitation and the geomagnetic activity and atmospheric circulation was carried out. The connection was found out to depend on a season. Cold periods in the northern hemisphere were characterized by a direct relationship between the geomagnetic activity and amount of precipitation in high latitudes, whereas a negative relationship was observed in sube-quatorial latitudes. In the framework of the model considered, the analysis results are presented and discussed of regularities of variations in geomagnetic activity and troposphere thermobaric characteristics for 1900-2007. It is showed that a continuous increase of the Earth climatic system heat content has been observed from 1910

  16. Forecasting geomagnetic activity at monthly and annual horizons: Time series models

    NASA Astrophysics Data System (ADS)

    Reikard, Gordon

    2015-10-01

    Most of the existing work on forecasting geomagnetic activity has been over short intervals, on the order of hours or days. However, it is also of interest to predict over longer horizons, ranging from months to years. Forecasting tests are run for the Aa index, which begins in 1868 and provides the longest continuous records of geomagnetic activity. This series is challenging to forecast. While it exhibits cycles at 11-22 years, the amplitude and period of the cycles varies over time. There is also evidence of discontinuous trending: the slope and direction of the trend change repeatedly. Further, at the monthly resolution, the data exhibits nonlinear variability, with intermittent large outliers. Several types of models are tested: regressions, neural networks, a frequency domain algorithm, and combined models. Forecasting tests are run at horizons of 1-11 years using the annual data, and 1-12 months using the monthly data. At the 1-year horizon, the mean errors are in the range of 13-17 percent while the median errors are in the range of 10-14 percent. The accuracy of the models deteriorates at longer horizons. At 5 years, the mean errors lie in the range of 21-23 percent, and at 11 years, 23-25 percent. At the 1 year horizon, the most accurate forecast is achieved by a combined model, but over longer horizons (2-11 years), the neural net dominates. At the monthly resolution, the mean errors are in the range of 17-19 percent at 1 month, while the median errors lie in a range of 14-17 percent. The mean error increases to 23-24 percent at 5 months, and 25 percent at 12 months. A model combining frequency and time domain methods is marginally better than regressions and neural networks alone, up to 11 months. The main conclusion is that geomagnetic activity can only be predicted to within a limited threshold of accuracy, over a given range of horizons. This is consistent with the finding of irregular trends and cycles in the annual data and nonlinear variability in

  17. Active control and synchronization chaotic satellite via the geomagnetic Lorentz force

    NASA Astrophysics Data System (ADS)

    Abdel-Aziz, Yehia

    2016-07-01

    The use of geomagnetic Lorentz force is considered in this paper for the purpose of satellite attitude control. A satellite with an electrostatic charge will interact with the Earth's magnetic field and experience the Lorentz force. An analytical attitude control and synchronization two identical chaotic satellite systems with different initial condition Master/ Slave are proposed to allows a charged satellite remains near the desired attitude. Asymptotic stability for the closed-loop system are investigated by means of Lyapunov stability theorem. The control feasibility depend on the charge requirement. Given a significantly and sufficiently accurate insertion, a charged satellite could maintains the desired attitude orientation without propellant. Simulations is performed to prove the efficacy of the proposed method.

  18. The evolution from weak to strong geomagnetic activity - An interpretation in terms of deterministic chaos

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Klimas, A. J.; Mcpherron, R. L.; Buechner, J.

    1990-01-01

    An analogue of the magnetosphere developed on the basis of Shaw's (1984) dripping faucet model was used to model the mechanisms of the magnetospheric response to energy transfer from the solar wind. It is demonstrated that geomagnetic activity results from nonlinearly coupled physical processes and that the strength and the nature of the coupling changes dramatically as the magnetosphere is driven harder and harder by increasing energy input. Based on initial results obtained from the model, is is suggested that a chaotic transition takes place in the analogue system as the loading rate is increased beyond a critical value. This model is able to explain many of the features in the results of linear prediction filtering techniques.

  19. Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Jiang, Guoying; Wang, Wenbin; Xu, Jiyao; Yue, Jia; Burns, Alan G.; Lei, Jiuhou; Mlynczak, Martin G.; Rusell, James M., III

    2015-04-01

    Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity and solar EUV radiation have been investigated using neutral temperature data observed by the TIMED/SABER (Thermosphere IonosphereMesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) instrument and numerical experiments by the NCAR-TIME-GCM (National Center for Atmospheric Research-thermosphere-ionosphere-mesosphere electrodynamics-general circulation model). The TIMED/SABER data analyzed were for the period from 2002 to 2007 during the declining phase of solar cycle 23. The observations show that the zonal mean temperature in the lower thermosphere oscillated with periods of near 9 and 13.5 days in the height range of 100-120 km. These oscillations were more strongly correlated with the recurrent geomagnetic activity than with the solar EUV variability of the same periods. The 9 day and 13.5 day oscillations of lower thermospheric temperature had greater amplitudes at high latitudes than at low latitudes; they also had larger amplitudes at higher altitudes, and the oscillations could penetrate down to ~105 km, depending on the strength of the recurrent geomagnetic activity for a particular time period. The data further show that the periodic responses of the lower thermospheric temperature to recurrent geomagnetic activity were different in the two hemispheres. In addition, numerical experiments have been carried out using the NCAR-TIME-GCM to investigate the causal relationship between the temperature oscillations and the geomagnetic activity and solar EUV variations of the same periods. Model simulations showed the same periodic oscillations as those seen in the observations when the real geomagnetic activity index, Kp, was used to drive the model. These numerical results show that recurrent geomagnetic activity is the main cause of the 9 day and 13.5 day variations in the lower thermosphere

  20. Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Jiang, Guoying; Wang, Wenbin; Xu, Jiyao; Yue, Jia; Burns, Alan G.; Lei, Jiuhou; Mlynczak, Martin G.; Rusell, James M.

    2014-06-01

    Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity and solar EUV radiation have been investigated using neutral temperature data observed by the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) instrument and numerical experiments by the NCAR-TIME-GCM (National Center for Atmospheric Research-thermosphere-ionosphere-mesosphere electrodynamics-general circulation model). The TIMED/SABER data analyzed were for the period from 2002 to 2007 during the declining phase of solar cycle 23. The observations show that the zonal mean temperature in the lower thermosphere oscillated with periods of near 9 and 13.5 days in the height range of 100-120 km. These oscillations were more strongly correlated with the recurrent geomagnetic activity than with the solar EUV variability of the same periods. The 9 day and 13.5 day oscillations of lower thermospheric temperature had greater amplitudes at high latitudes than at low latitudes; they also had larger amplitudes at higher altitudes, and the oscillations could penetrate down to ~105 km, depending on the strength of the recurrent geomagnetic activity for a particular time period. The data further show that the periodic responses of the lower thermospheric temperature to recurrent geomagnetic activity were different in the two hemispheres. In addition, numerical experiments have been carried out using the NCAR-TIME-GCM to investigate the causal relationship between the temperature oscillations and the geomagnetic activity and solar EUV variations of the same periods. Model simulations showed the same periodic oscillations as those seen in the observations when the real geomagnetic activity index, Kp, was used to drive the model. These numerical results show that recurrent geomagnetic activity is the main cause of the 9 day and 13.5 day variations in the lower thermosphere

  1. Geomagnetic polarity reversals, Earth's core evolution, and conditions for dynamo action in the cores of terrestrial exoplanets

    NASA Astrophysics Data System (ADS)

    Driscoll, Peter E.

    Planetary dynamos are responsible for the generation of large-scale magnetic fields and are ubiquitous in the solar system. Magnetic fields generated by dynamo action in a planetary core offer unique insight into the internal structure, composition, and energetics of the planet. This dissertation consists of two main parts, the first focuses on long period fluctuations in Earth's magnetic field and the second explores conditions for dynamo action in the cores of terrestrial exoplanets. The first part consists of three projects using first-principle numerical magnetohydrodynamic models of the geodynamo to investigate the relationship between two fundamental, but poorly understood, aspects of the geomagnetic field: magnetic polarity reversals and the influence of core evolution. The first project explores the dependence of various dynamo properties on the relative strengths of buoyancy and rotation, and identifies several dynamical regimes whose magnetic field fluctuations over time are consistent with the paleomagnetic field. We find that normal evolution of buoyancy production in the core and planetary rotation rate over 100 Myr produce a negligible change in dynamo polarity reversal rate and field intensity, implying that the observed fluctuations in the geomagnetic reversal rate requires either anomalous core evolution or a rough dynamo regime boundary. The second project models the long time-scale evolution of the Earth's core using time-dependent control parameters, which are constrained by the secular cooling of the core and tidal deceleration. We find that fluctuations in the geodynamo are closely coupled to the evolution of the core, which implies a connection between the long time-scale trends in the seafloor geomagnetic polarity reversal rate and the rate of core evolution over the last 100 Myr. In the third project we investigate the hypothesis that the long period (˜200 Myr) oscillation in paleomagnetic reversal frequency is controlled by the heat flow

  2. Intraocular pressure (IOP) in relation to four levels of daily geomagnetic and extreme yearly solar activity

    NASA Astrophysics Data System (ADS)

    Stoupel, E.; Goldenfeld, M.; Shimshoni, M.; Siegel, R.

    1993-03-01

    The link between geomagnetic field activity (GMA), solar activity and intraocular pressure (IOP) in healthy individuals was investigated. The IOP of 485 patients (970 eyes) was recorded over three nonconsecutive years (1979, 1986, 1989) which were characterized by maximal solar activity (1979, 1989) or minimal solar activity (1986). The measurements were also correlated with four categories of GMA activity: quiet (level I0), unsettled (II0), active (III0), and stormy (IV0). Participants were also differentiated by age and sex. We found that IOP was lowest on days of level IV0 (stormy) GMA. The drop in IOP concomitant with a decrease in GMA level was more significant during periods of low solar activity and in persons over 65 years of age. There was a trend towards higher IOP values on days of levels II0 and IV0 GMA in years of high solar activity. Differences between the sexes and among individuals younger than 65 years were not significant. Our results show an interesting aspect of environmental influence on the healthy population.

  3. Intraocular pressure (IOP) in relation to four levels of daily geomagnetic and extreme yearly solar activity.

    PubMed

    Stoupel, E; Goldenfeld, M; Shimshoni, M; Siegel, R

    1993-02-01

    The link between geomagnetic field activity (GMA), solar activity and intraocular pressure (IOP) in healthy individuals was investigated. The IOP of 485 patients (970 eyes) was recorded over three nonconsecutive years (1979, 1986, 1989) which were characterized by maximal solar activity (1979, 1989) or minimal solar activity (1986). The measurements were also correlated with four categories of GMA activity: quiet (level I0), unsettled (II0), active (III0), and stormy (IV0). Participants were also differentiated by age and sex. We found that IOP was lowest on days of level IV0 (stromy) GMA. The drop in IOP concomitant with a decrease in GMA level was more significant during periods of low solar activity and in persons over 65 years of age. There was a trend towards higher IOP values on days of levels II0 and IV0 GMA in years of high solar activity. Differences between the sexes and among individuals younger than 65 years were not significant. Our results show an interesting aspect of environmental influence on the healthy population. PMID:8468099

  4. MLT dependence in the relationship between plasmapause, solar wind, and geomagnetic activity based on CRRES: 1990-1991

    NASA Astrophysics Data System (ADS)

    Bandić, Mario; Verbanac, Giuli; Moldwin, Mark B.; Pierrard, Viviane; Piredda, Giovanni

    2016-05-01

    Using the database of CRRES in situ observations of the plasmapause crossings, we develop linear and more complex plasmapause models parametrized by (a) solar wind parameters V (solar wind velocity), BV (where B is the magnitude of the interplanetary magnetic field (IMF)), and dΦmp/dt (which combines different physical mechanisms which run magnetospheric activity), and (b) geomagnetic indices Dst, Ap, and AE. The complex models are built by including a first harmonic in magnetic local time (MLT). Our method based on the cross-correlation analyses provides not only the plasmapause shape for different levels of geomagnetic activity but additionally yields the information of the delays in the MLT response of the plasmapause. All models based on both solar wind parameters and geomagnetic indices indicate the maximal plasmapause extension in the postdusk side at high geomagnetic activity. The decrease in the convection electric field places the bulge toward midnight. These results are compared and discussed in regard to past works. Our study shows that the time delays in the plasmapause response are a function of MLT and suggests that the plasmapause is formed by the mechanism of interchange instability motion. We observed that any change quickly propagates across dawn to noon, and then at lower rate toward midnight. The results further indicate that the instability may propagate much faster during solar maximum than around solar minimum. This study contributes to the determination of the MLT dependence of the plasmapause and to constrain physical mechanism by which the plasmapause is formed.

  5. Comment on ``Annual variation of geomagnetic activity'' by Alicia L. Clúa de Gonzales et al.

    NASA Astrophysics Data System (ADS)

    Sonnemann, G. R.

    2002-10-01

    Clúa de Gonzales et al. (J. Atmos. Terr. Phys. 63 (2001) 367) analyzed the monthly means of the geomagnetic /aa-index available since 1868 and found enhanced geomagnetic activity in July outside of the known seasonal course of semiannual variation. They pointed out that this behavior is mainly caused by the high values of the geomagnetic activity. Their analysis confirmed results obtained from an analysis of Ap-values nearly 30 years ago but widely unknown to the scientific community. At that time the entire year was analyzed using running means of the activity values averaged to the same date. Aside from the July period, the calculations revealed distinct deviations from the seasonal course-called geomagnetic singularities. The most marked singularity occurs from the middle of March to the end of March characterized by a strong increase from, on average, relatively calm values to the actually strongest ones during the entire year. Some typical time patterns around and after equinox are repeated half a year later. An analysis in 1998 on the basis of the available /aa-values confirmed the findings derived from Ap-values and the local activity index Ak from Niemegk, Germany available since 1890. The new results will be presented and discussed. Special attention is paid to the statistical problem of the persistence of geomagnetic perturbations. The main problem under consideration is that the variation of the mean activity is not caused by an accidental accumulation of strong perturbations occurring within certain intervals of days. We assume that the most marked variations of the mean value are not accidental and result from internal processes within the earth's atmosphere but different, particularly small-scale features, are most probably accidental.

  6. Maximum Coronal Mass Ejection Speed as an Indicator of Solar and Geomagnetic Activities

    NASA Astrophysics Data System (ADS)

    Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Gopalswamy, N.; Ozguc, A.; Rozelot, J. P.

    2011-01-01

    We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions.

  7. The association between phenomena on the Sun, geomagnetic activity, meteorological variables, and cardiovascular characteristic of patients with myocardial infarction

    NASA Astrophysics Data System (ADS)

    Vencloviene, Jone; Babarskiene, Ruta; Slapikas, Rimvydas; Sakalyte, Gintare

    2013-09-01

    It has been found that solar and geomagnetic activity affects the cardiovascular system. Some evidence has been reported on the increase in the rate of myocardial infarction, stroke and myocardial infarction related deaths during geomagnetic storms. We investigated the association between cardiovascular characteristics of patients, admitted for myocardial infarction with ST elevation (STEMI), and geomagnetic activity (GMA), solar proton events (SPE), solar flares, and meteorological variables during admission. The data of 1,979 patients hospitalized at the Hospital of Lithuanian University of Health Sciences (Kaunas) were analyzed. We evaluated the association between environmental variables and patient's characteristics by multivariate logistic regression, controlling patient's gender and age. Two days after geomagnetic storms the risk of STEMI was over 1.5 times increased in patients who had a medical history of myocardial infarction, stable angina, renal or pulmonary diseases. The dose-response association between GMA level and STEMI risk for patients with renal diseases in history was observed. Two days after SPE the risk of STEMI in patients with stable angina in anamnesis was increased over 1.5 times, adjusting by GMA level. The SPE were associated with an increase of risk for patients with renal diseases in history. This study confirms the strongest effect of phenomena in the Sun in high risk patients.

  8. On the statistics of El Nino occurrences and the relationship of El Nino to volcanic and solar/geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1989-01-01

    El Nino is conventionally defined as an anomalous and persistent warming of the waters off the coasts of Ecuador and Peru in the eastern equatorial Pacific, having onset usually in Southern Hemispheric summer/fall. Some of the statistical aspects of El Nino occurrences are examined, especially as they relate to the normal distribution and to possible associations with volcanic, solar, and geomagnetic activity. With regard to the very strong El Nino of 1982 to 1983, it is noted that, although it may very well be related to the 1982 eruptions of El Chichon, the event occurred essentially on time (with respect to the past behavior of elapsed times between successive El Nino events; a moderate-to-stronger El Nino was expected during the interval 1978 to 1982, assuming that El Nino occurrences are normally distributed, having a mean elapsed time between successive onsets of 4 years and a standard deviation of 2 years and a last known occurrence in 1976). Also, although not widely recognized, the whole of 1982 was a record year for geomagnetic activity (based on the aa geomagnetic index, with the aa index registering an all time high in February 1982), perhaps, important for determining a possible trigger for this and other El Nino events. A major feature is an extensive bibliography (325 entries) on El Nino and volcanic-solar-geomagnetic effects on climate. Also, included is a tabular listing of the 94 major volcanic eruptions of 1835 to 1986.

  9. The association between phenomena on the sun, geomagnetic activity, meteorological variables, and cardiovascular characteristic of patients with myocardial infarction.

    PubMed

    Vencloviene, Jone; Babarskiene, Ruta; Slapikas, Rimvydas; Sakalyte, Gintare

    2013-09-01

    It has been found that solar and geomagnetic activity affects the cardiovascular system. Some evidence has been reported on the increase in the rate of myocardial infarction, stroke and myocardial infarction related deaths during geomagnetic storms. We investigated the association between cardiovascular characteristics of patients, admitted for myocardial infarction with ST elevation (STEMI), and geomagnetic activity (GMA), solar proton events (SPE), solar flares, and meteorological variables during admission. The data of 1,979 patients hospitalized at the Hospital of Lithuanian University of Health Sciences (Kaunas) were analyzed. We evaluated the association between environmental variables and patient's characteristics by multivariate logistic regression, controlling patient's gender and age. Two days after geomagnetic storms the risk of STEMI was over 1.5 times increased in patients who had a medical history of myocardial infarction, stable angina, renal or pulmonary diseases. The dose-response association between GMA level and STEMI risk for patients with renal diseases in history was observed. Two days after SPE the risk of STEMI in patients with stable angina in anamnesis was increased over 1.5 times, adjusting by GMA level. The SPE were associated with an increase of risk for patients with renal diseases in history. This study confirms the strongest effect of phenomena in the Sun in high risk patients.

  10. The association between phenomena on the sun, geomagnetic activity, meteorological variables, and cardiovascular characteristic of patients with myocardial infarction.

    PubMed

    Vencloviene, Jone; Babarskiene, Ruta; Slapikas, Rimvydas; Sakalyte, Gintare

    2013-09-01

    It has been found that solar and geomagnetic activity affects the cardiovascular system. Some evidence has been reported on the increase in the rate of myocardial infarction, stroke and myocardial infarction related deaths during geomagnetic storms. We investigated the association between cardiovascular characteristics of patients, admitted for myocardial infarction with ST elevation (STEMI), and geomagnetic activity (GMA), solar proton events (SPE), solar flares, and meteorological variables during admission. The data of 1,979 patients hospitalized at the Hospital of Lithuanian University of Health Sciences (Kaunas) were analyzed. We evaluated the association between environmental variables and patient's characteristics by multivariate logistic regression, controlling patient's gender and age. Two days after geomagnetic storms the risk of STEMI was over 1.5 times increased in patients who had a medical history of myocardial infarction, stable angina, renal or pulmonary diseases. The dose-response association between GMA level and STEMI risk for patients with renal diseases in history was observed. Two days after SPE the risk of STEMI in patients with stable angina in anamnesis was increased over 1.5 times, adjusting by GMA level. The SPE were associated with an increase of risk for patients with renal diseases in history. This study confirms the strongest effect of phenomena in the Sun in high risk patients. PMID:23179321

  11. Graded response of heart rate variability, associated with an alteration of geomagnetic activity in a subarctic area.

    PubMed

    Oinuma, S; Kubo, Y; Otsuka, K; Yamanaka, T; Murakami, S; Matsuoka, O; Ohkawa, S; Cornélissen, G; Weydahl, A; Holmeslet, B; Hall, C; Halberg, F

    2002-01-01

    It is becoming recognized that geomagnetic activity may influence biological processes, including the incidence of various human diseases. There is evidence that heart rate variability (HRV) may serve not only as an index of autonomic coordination of the circulation, but also as a powerful predictor of risk in apparently healthy subjects. This study focuses on the effects of geomagnetic disturbance on HRV, by comparing different indices of HRV of young, healthy men living in a subarctic area on days of low (Ap; 0-7), middle (Ap; 7-20), and high (Ap; 20-45) geomagnetic activity. The effect of geomagnetic disturbance on HRV is examined on the basis of 7-day records by Holter ECG, obtained longitudinally on 5 clinically healthy men, 21-31 years of age, in Alta, Norway (70 degree N). Frequency- and time-domain measures of HRV were analyzed for each subject on separate 24-hour spans. A graded alteration of HRV endpoints was found in association with increased geomagnetic activity. As time-domain measures of HRV, SDNNIDX and the 90% length of the Lorenz plot decreased statistically significantly on days with increased geomagnetic disturbance (p = 0.0144 and p = 0.0102, respectively). A graded decrease in frequency-domain HRV measures was also validated statistically for the total spectral power (decrease of 18.1% and 31.6% on days when 7 < Ap < 20 and 20 < Ap < 45 versus days when Ap < 7; p = 0.0013). The decrease in spectral power was mainly found at frequencies below 0.04 Hz, in the "ultra-low-frequency" (0.0001-0.003 Hz; 18.1% and 27.5% decrease, respectively; p = 0.0102) and "very-low-frequency" (0.003-0.04 Hz; 12.9% and 28.6% decrease, respectively; p = 0.0209) regions of the spectrum. The decrease in spectral power was much less pronounced around 10.5 sec ("low frequency"; N.S.) and around 3.6 sec ("high frequency"; N.S.). Evidence is provided here that HRV decreases on magnetically disturbed days, and that it does so in a dose-dependent fashion, HRV being

  12. First observations of poleward large-scale traveling ionospheric disturbances over the African sector during geomagnetic storm conditions

    NASA Astrophysics Data System (ADS)

    Habarulema, John Bosco; Katamzi, Zama Thobeka; Yizengaw, Endawoke

    2015-08-01

    This paper presents first observations of poleward traveling ionospheric disturbances (TIDs) during strong geomagnetic conditions over the African sector. By analyzing different data sets we have observed both positive and negative ionospheric responses during the storm period of 08-10 March 2012. Considering the African region as a whole, three longitudinal sectors were strategically selected to establish the entire regional response. On both sides of the geomagnetic equator, results show poleward shift in peak total electron content (TEC) enhancements/depletions at different times which are associated to large-scale TIDs. The observed phenomena are linked to the global ionospheric response and electrodynamics. The understanding has been established using data from International GNSS Service receiver network, radio occultation electron density profiles, derived E×B drift measurements from magnetometer observations and regional ground-based and satellite data. Contrary to other related studies, generated regional TEC perturbation maps were not enough to show obvious directions of the large-scale TIDs due to insufficient data over the northern hemispheric part of the African sector. There appears to be a switch between positive and negative storm phases during the same storm period especially in the Southern Hemisphere part of the African region where "enough" data were available. However, a detailed analysis revealed that the positive storm phase corresponded to the expansion of the equatorial ionization anomaly (EIA) toward some parts of midlatitude regions (and possibly with the contribution from low-latitude electrodynamics associated to equatorial electrojet), while the other part recorded a negative storm phase due to storm-induced changes from the auroral origin. We have observed a simultaneous occurrence of both poleward and equatorward propagating TIDs over the African sector during the same geomagnetic storm period. Our results show that short-lived large

  13. The Causes of Geomagnetic Storms During Solar Maximum

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Gonzalez, W. D.

    1998-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine (1852).

  14. Geomagnetic and solar activity dependence of ionospheric upflowing O+: FAST observations

    NASA Astrophysics Data System (ADS)

    Zhao, K.; Jiang, Y.; Chen, K. W.; Huang, L. F.

    2016-09-01

    This paper investigates the dependence of the occurrence frequency of ionospheric upflowing oxygen (O+) ions on the sunspot cycle and geomagnetic activity. We examine the upflows response to the geomagnetic disturbances as well as the influence of the ion energy factor in controlling the magnitude of the occurrence frequency and the net energy flux. We discuss the spatial distribution of the upflow occurrence frequency and construct a regression model as a function of the magnetic latitude. The results show an overall enhancement of the upflow occurrence frequency during magnetically disturbed periods and indicate that the high-occurrence area spreads out from the source regions during magnetically quiet periods. The high-occurrence areas are located at 70° magnetic latitude (mLat) in the dayside auroral oval zone and between 76-80° mLat in the dayside polar cusp region. In the nightside auroral oval zone, these areas are near 60° mLat, penetrating further equatorward to 55° mLat during magnetically disturbed periods. High energy (≥1 keV) upflowing ions are common in the nightside auroral oval zone while low energy (<1 keV) upflowing ions are found escaping from the high latitude dayside cusp region. A Gaussian function is shown to be a good fit to the occurrence frequency over the magnetic latitude. For high energy upflowing O+ ions, the occurrence frequency exhibits a single peak located at about 60° mLat in the nightside auroral oval zone while for low energy upflowing O+ ions, it exhibits two peaks, one near 60° mLat in the auroral oval zone and the other near 78° mLat in the cusp region. We study the solar activity dependence by analyzing the relationship between the upflow occurrence frequency and the sunspot number (RZ). The statistical result shows that the frequency decreases with declining solar activity level, from ˜30 % at solar maximum to ˜5 % at solar minimum. In addition, the correlation coefficient between the occurrence frequency and RZ

  15. Study on Na layer response to geomagnetic activities based on Odin/OSIRIS Na density data

    NASA Astrophysics Data System (ADS)

    Tsuda, Takuo; Nakamura, Takuji; Hedin, Jonas; Gumbel, Jorg; Hosokawa, Keisuke; Ejiri, Mitsumu K.; Nishiyama, Takanori; Takahashi, Toru

    2016-07-01

    The Na layer is normally distributed from 80 to 110 km, and the height range is corresponding to the ionospheric D and E region. In the polar region, the energetic particles precipitating from the magnetosphere can often penetrate into the E region and even into the D region. Thus, the influence of the energetic particles to the Na layer is one of interests in the aspect of the atmospheric composition change accompanied with the auroral activity. There are several previous studies in this issue. For example, recently, we have reported an initial result on a clear relationship between the electron density increase (due to the energetic particles) and the Na density decrease from observational data sets obtained by Na lidar, EISCAT VHF radar, and optical instruments at Tromsoe, Norway on 24-25 January 2012. However, all of the previous studies had been carried out based on case studies by ground-based lidar observations. In this study, we have performed, for the first time, statistical analysis using Na density data from 2004 to 2009 obtained with the Optical Spectrograph and InfraRed Imager System (OSIRIS) onboard Odin satellite. In the presentation, we will show relationship between the Na density and geomagnetic activities, and its latitudinal variation. Based on these results, the Na layer response to the energetic particles will be discussed.

  16. Statistical analysis on Na layer response to geomagnetic activities using Odin/OSIRIS data

    NASA Astrophysics Data System (ADS)

    Tsuda, Takuo T.; Nakamura, Takuji; Ejiri, Mitsumu K.; Nishiyama, Takanori; Hosokawa, Keisuke; Takahashi, Toru; Gumbel, Jörg; Hedin, Jonas

    2016-04-01

    The Na layer is normally distributed from 80 to 110 km, and the height range is corresponding to the ionospheric D and E region. In the polar region, the energetic particles precipitating from the magnetosphere can often penetrate into the E region and even into the D region. Thus, the influence of the energetic particles to the Na layer is one of interests in the aspect of the atmospheric composition change accompanied with the auroral activity. There are several previous studies in this issue. For example, recently, we have reported an initial result on a clear relationship between the electron density increase (due to the energetic particles) and the Na density decrease from observational dataset obtained by Na lidar, EISCAT VHF radar, and optical instruments at Tromsoe, Norway on 24-25 January 2012. However, all of the previous studies had been carried out based on case studies by ground-based lidar observations. In this study, we have performed, for the first time, statistical analysis using Na density data from 2004 to 2009 obtained with the Optical Spectrograph and InfraRed Imager System (OSIRIS) onboard Odin satellite. In the presentation, we will show relationship between the Na density and geomagnetic activities, and its latitudinal variation. Based on these results, the Na layer response to the energetic particles will be discussed.

  17. The Dst index underestimates the solar cycle variation of geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Temerin, Michael; Li, Xinlin

    2015-07-01

    It is known that the correction of the Kyoto Dst index for the secular variation of the Earth's internal field produces a discontinuity in the Kyoto Dst index at the end of each year. We show that this secular correction also introduces a significant baseline error to the Kyoto Dst index that leads to an underestimate of the solar cycle variation of geomagnetic activity and of the strength of the ring current as measured by the Kyoto Dst index. Thus, the average value of the Kyoto Dst index would be approximately 13 nT more negative for the active year 2003 compared to quiet years 2006 and 2009 if the Kyoto Dst index properly measured the effects of the ring current and other currents that influence the Dst observatories. Discontinuities in the Kyoto Dst index at the end of each year have an average value of about 5 nT, but the discontinuity at the end of year 2002 was approximately 12 nT, and the discontinuity at the end of year 1982 may have been as large as 20 nT.

  18. Sub- and Quasi-Centurial Cycles in Solar and Geomagnetic Activity Data Series

    NASA Astrophysics Data System (ADS)

    Komitov, B.; Sello, S.; Duchlev, P.; Dechev, M.; Penev, K.; Koleva, K.

    2016-07-01

    The subject of this paper is the existence and stability of solar cycles with durations in the range of 20-250 years. Five types of data series are used: 1) the Zurich series (1749-2009 AD), the mean annual International sunspot number Ri, 2) the Group sunspot number series Rh (1610-1995 AD), 3) the simulated extended sunspot number from Extended time series of Solar Activity Indices (ESAI) (1090-2002 AD), 4) the simulated extended geomagnetic aa-index from ESAI (1099-2002 AD), 5) the Meudon filament series (1919-1991 AD). Two principally independent methods of time series analysis are used: the T-R periodogram analysis (both in standard and ``scanning window'' regimes) and the wavelet-analysis. The obtained results are very similar. A strong cycle with a mean duration of 55-60 years is found to exist in all series. On the other hand, a strong and stable quasi 110-120 years and ˜200-year cycles are obtained in all of these series except in the Ri one. The high importance of the long term solar activity dynamics for the aims of solar dynamo modeling and predictions is especially noted.

  19. Do ambient electromagnetic fields affect behaviour? A demonstration of the relationship between geomagnetic storm activity and suicide.

    PubMed

    Berk, Michael; Dodd, Seetal; Henry, Margaret

    2006-02-01

    The relationship between ambient electromagnetic fields and human mood and behaviour is of great public health interest. The relationship between Ap indices of geomagnetic storm activity and national suicide statistics for Australia from 1968 to 2002 was studied. Ap index data was normalised so as to be globally uniform and gave a measure of storm activity for each day. A geomagnetic storm event was defined as a day in which the Ap index was equal to or exceeded 100 nT. Suicide data was a national tally of daily male and female death figures where suicide had been documented as the cause of death. A total of 51 845 males and 16 327 females were included. The average number of suicides was greatest in spring for males and females, and lowest in autumn for males and summer for females. Suicide amongst females increased significantly in autumn during concurrent periods of geomagnetic storm activity (P = .01). This pattern was not observed in males (P = .16). This suggests that perturbations in ambient electromagnetic field activity impact behaviour in a clinically meaningful manner. The study furthermore raises issues regarding other sources of stray electromagnetic fields and their effect on mental health. PMID:16304696

  20. Geomagnetism applications

    USGS Publications Warehouse

    Campbell, Wallace H.

    1995-01-01

    The social uses of geomagnetism include the physics of the space environment, satellite damage, pipeline corrosion, electric power-grid failure, communication interference, global positioning disruption, mineral-resource detection, interpretation of the Earth's formation and structure, navigation, weather, and magnetoreception in organisms. The need for continuing observations of the geomagnetic field, together with careful archiving of these records and mechanisms for dissemination of these data, is emphasized.

  1. Human physiological reaction to geomagnetic disturbances of solar origin

    NASA Astrophysics Data System (ADS)

    Dimitrova, Sv.; Stoilova, I.

    2002-12-01

    During the last two decades publications about the influence of geomagnetic activity on human health increase but there are not still strong evidences for this relationship. We performed measurements and observations of 86 working volunteers during the period of autumn and spring equinox. We examined systolic, diastolic blood pressure and pulse rate. We also collected data for some personal health condition complaints. Four-way analyses of variance (MANOVA method) were employed and the influence of factors geomagnetic activity level, sequence of the days of measurements with respect to the increased geomagnetic activity, medicaments and sex was investigated. We also performed three-way analyses of variance and investigated influence of atmospheric pressure, medicaments and sex on the physiological parameters under consideration. Our investigations indicate that most of the persons examined irrespectively to their health status could be sensitive to the geomagnetic changes, which influence directly self-confidence and working ability.

  2. The relationship between plasmapause, solar wind and geomagnetic activity between 2007 and 2011

    NASA Astrophysics Data System (ADS)

    Verbanac, G.; Pierrard, V.; Bandić, M.; Darrouzet, F.; Rauch, J.-L.; Décréau, P.

    2015-10-01

    Taking advantage of the Cluster satellite mission and especially the observations made by the instrument WHISPER to deduce the electron number density along the orbit of the satellites, we studied the relationships between the plasmapause positions (LPP) and the following LPP indicators: (a) solar wind coupling functions Bz (Z component of the interplanetary magnetic field vector, B, in GSM system), BV (related to the interplanetary electric field; B is the magnitude of the interplanetary magnetic field vector, V is solar wind velocity), and dΦmp/dt (which combines different physical processes responsible for the magnetospheric activity) and (b) geomagnetic indices Dst, Ap and AE. The analysis is performed separately for three magnetic local time (MLT) sectors (Sector1 - night sector (01:00-07:00 MLT); Sector2 - day sector (07:00-16:00 MLT); Sector3 - evening sector (16:00-01:00 MLT)) and for all MLTs taken together. All LPP indicators suggest the faster plasmapause response in the postmidnight sector. Delays in the plasmapause responses (hereafter time lags) are approximately 2-27 h, always increasing from Sector1 to Sector3. The obtained fits clearly resolve the MLT structures. The variability in the plasmapause is the largest for low values of LPP indicators, especially in Sector2. At low activity levels,LPP exhibits the largest values on the dayside (in Sector2) and the smallest on the postmidnight side (Sector1). Displacements towards larger values on the evening side (Sector3) and towards lower values on the dayside (Sector2) are identified for enhanced magnetic activity. Our results contribute to constraining the physical mechanisms involved in the plasmapause formation and to further study the still not well understood related issues.

  3. Strong ambipolar-driven ion upflow within the cleft ion fountain during low geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Shen, Yangyang; Knudsen, David J.; Burchill, Johnathan K.; Howarth, Andrew; Yau, Andrew; Redmon, Robert J.; Miles, David M.; Varney, Roger H.; Nicolls, Michael J.

    2016-07-01

    We investigate low-energy (<10 eV) ion upflows (mainly O+) within the cleft ion fountain (CIF) using conjunctions of the Enhanced Polar Outflow Probe (e-POP) satellite, the DMSP F16 satellite, the SuperDARN radar, and the Resolute Bay Incoherent Scatter Radar North (RISR-N). The SEI instrument on board e-POP enables us to derive ion upflow velocities from the 2-D images of ion distribution functions with a frame rate of 100 images per second, and with a velocity resolution of the order of 25 m/s. We identify three cleft ion fountain events with very intense (>1.6 km/s) ion upflow velocities near 1000 km altitude during quiet geomagnetic activity (Kp < 3). Such large ion upflow velocities have been reported previously at or below 1000 km, but only during active periods. Analysis of the core ion distribution images allows us to demonstrate that the ion temperature within the CIF does not rise by more than 0.3 eV relative to background values, which is consistent with RISR-N observations in the F region. The presence of soft electron precipitation seen by DMSP and lack of significant ion heating indicate that the ion upflows we observe near 1000 km altitude are primarily driven by ambipolar electric fields. DC field-aligned currents (FACs) and convection velocity gradients accompany these events. The strongest ion upflows are associated with downward current regions, which is consistent with some (although not all) previously published results. The moderate correlation coefficient (0.51) between upflow velocities and currents implies that FACs serve as indirect energy inputs to the ion upflow process.

  4. Solar energetic particle flux enhancement as a predictor of geomagnetic activity in a neural network-based model

    NASA Astrophysics Data System (ADS)

    Valach, F.; Revallo, M.; Bochníček, J.; Hejda, P.

    2009-04-01

    Coronal mass ejections (CMEs) are believed to be the principal cause of increased geomagnetic activity. They are regarded as being in context of a series of related solar energetic events, such as X-ray flares (XRAs) accompanied by solar radio bursts (RSPs) and also by solar energetic particle (SEP) flux. Two types of the RSP events are known to be geoeffective, namely, the RSP of type II, interpreted as the signature of shock initiation in the solar corona, and type IV, representing material moving upward in the corona. The SEP events causing geomagnetic response are known to be produced by CME-driven shocks. In this paper, we use the method of the artificial neural network in order to quantify the geomagnetic response of particular solar events. The data concerning XRAs and RSPs II and/or IV together with their heliographic positions are taken as the input for the neural network. There is a key question posed in our study: can the successfulness of the neural network prediction scheme based solely on the solar disc observations (XRA and RSP) be improved by additional information concerning the SEP flux? To resolve this problem, we chose the SEP events possessing significant enhancement in the 10-h window, commencing 12 h after the generation of XRAs. In particular, we consider the flux of high-energy protons with energies over 10 MeV. We have used a chi-square test to demonstrate that supplying such extra input data improves the neural network prediction scheme.

  5. Van Allen Probes observation and modeling of chorus excitation and propagation during weak geomagnetic activities

    SciTech Connect

    He, Yihua; Xiao, Fuliang; Zhou, Qinghua; Yang, Chang; Liu, Si; Baker, D. N.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.; Blake, J. B.

    2015-08-20

    We report correlated data on nightside chorus waves and energetic electrons during two small storm periods: 1 November 2012 (Dst ≈ –45) and 14 January 2013 (Dst ≈ –18). The Van Allen Probes simultaneously observed strong chorus waves at locations L = 5.8 – 6.3, with a lower frequency band 0.1–0.5fce and a peak spectral density ~10–4 nT2/Hz. In the same period, the fluxes and anisotropy of energetic (~10–300 keV) electrons were greatly enhanced in the interval of large negative interplanetary magnetic field Bz. Using a bi-Maxwellian distribution to model the observed electron distribution, we perform ray tracing simulations to show that nightside chorus waves are indeed produced by the observed electron distribution with a peak growth for a field-aligned propagation approximately between 0.3fce and 0.4fce, at latitude <7°. Moreover, chorus waves launched with initial normal angles either θ < 90° or > 90° propagate along the field either northward or southward and then bounce back either away from Earth for a lower frequency or toward Earth for higher frequencies. The current results indicate that nightside chorus waves can be excited even during weak geomagnetic activities in cases of continuous injection associated with negative Bz. Furthermore, we examine a dayside event during a small storm C on 8 May 2014 (Dst ≈ –45) and find that the observed anisotropic energetic electron distributions potentially contribute to the generation of dayside chorus waves, but this requires more thorough studies in the future.

  6. Van Allen Probes observation and modeling of chorus excitation and propagation during weak geomagnetic activities

    DOE PAGES

    He, Yihua; Xiao, Fuliang; Zhou, Qinghua; Yang, Chang; Liu, Si; Baker, D. N.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Spence, H. E.; et al

    2015-08-20

    We report correlated data on nightside chorus waves and energetic electrons during two small storm periods: 1 November 2012 (Dst ≈ –45) and 14 January 2013 (Dst ≈ –18). The Van Allen Probes simultaneously observed strong chorus waves at locations L = 5.8 – 6.3, with a lower frequency band 0.1–0.5fce and a peak spectral density ~10–4 nT2/Hz. In the same period, the fluxes and anisotropy of energetic (~10–300 keV) electrons were greatly enhanced in the interval of large negative interplanetary magnetic field Bz. Using a bi-Maxwellian distribution to model the observed electron distribution, we perform ray tracing simulations tomore » show that nightside chorus waves are indeed produced by the observed electron distribution with a peak growth for a field-aligned propagation approximately between 0.3fce and 0.4fce, at latitude <7°. Moreover, chorus waves launched with initial normal angles either θ < 90° or > 90° propagate along the field either northward or southward and then bounce back either away from Earth for a lower frequency or toward Earth for higher frequencies. The current results indicate that nightside chorus waves can be excited even during weak geomagnetic activities in cases of continuous injection associated with negative Bz. Furthermore, we examine a dayside event during a small storm C on 8 May 2014 (Dst ≈ –45) and find that the observed anisotropic energetic electron distributions potentially contribute to the generation of dayside chorus waves, but this requires more thorough studies in the future.« less

  7. Distribution of the Effect of Solar Proton Flux And Geomagnetic Activity on the Stratospheric Ozone Profile

    NASA Astrophysics Data System (ADS)

    Velinov, P. I. Y.; Tassev, Y.; Yanev, T.; Tomova, D.

    Two-way MANOVA was used to examine the impact of two factors: 1) the proton flux intensity and 2) the geomagnetic activity on the dependant variable "ozone mixing ratio" which characterizes the stratospheric ozone profiles. The examination was carried out with fixed levels of two other factors: a) the heights at which the "ozone mixing ratio" was recorded, i,e, 35 km, 30.2 km, 24.5 km, 18.4 km, 15.6 km and b) the energetic intervals within which the proton flux was measured, i.e. =0,6-4,2 MeV; 4,2-8,7 MeV; 8,7-14,5 MeV; 15-44 MeV; 39-82 MeV; 84-200 MeV; 110-500 MeV. The analysis was performed for all combinations of levels of the factors a) and b) for which data was available. It was aimed at revealing which of the factors 1) and 2) were dominating with different combinations of the factors a) and b) with fixed levels. For this purpose a post hoc analysis was performed as well. The main results are as follows: factors 1) and 2) exert statistically significant impact on the dependant variable at all of the heights examined, but not for all of energetic intervals; increase of the ozone mixing ratio was observed as a main effect of the proton flux intensity at heights 24.5 km, 18.4 km, 15.6 km, but the analysis of the simultaneous acting of factors 1) and 2) revealed a decrease of the dependant variable at these heights; these effects possibly indicate the existence of two different mechanisms of impact on the ozone mixing ratio; the afore- discussed effects decrease with the height and therefore their graphical image was named "Christmas tree".

  8. Correlation of Geomagnetic Activity with Implantable Cardioverter Defibrillator Shocks and Antitachycardia Pacing

    PubMed Central

    Ebrille, Elisa; Konecny, Tomas; Konecny, Dana; Spacek, Radim; Jones, Paul; Ambroz, Pavel; DeSimone, Christopher V; Powell, Brian D; Hayes, David L; Friedman, Paul A; Asirvatham, Samuel J

    2016-01-01

    Objective Small-scale observational studies have suggested that geomagnetic activity (GMA) may negatively correlate with the frequency of life-threatening arrhythmias. We investigated a potential relationship between implantable cardioverter defibrillator (ICD) therapies and daily GMA recorded in a large database. Patients and Methods The ALTITUDE database, derived from the Boston Scientific LATITUDE remote monitoring system, was retrospectively analyzed for the frequency of ICD therapies. Daily GMA was expressed as the planetary K-index and the integrated A-index and graded as Levels I – quiet, II – unsettled, III – active, and IV – storm. Results A daily mean of 59,468 ± 11,397 patients were monitored between 2009 and 2012. The distribution of days according to GMA was: Level I 75%, Level II 18%, Level III 5%, Level IV 2%. The daily number of ICD shocks received per 1000 active patients in the database was 1.29 ± 0.47, 1.17 ± 0.46, 1.03 ± 0.37, and 0.94 ± 0.29 on Level I, Level II, Level III, and Level IV days respectively; the daily sum of shocks and antitachycardia pacing (ATP) therapies was 9.29 ± 2.86, 8.46 ± 2.45, 7.92 ± 1.80, and 7.83 ± 2.28 on quiet, unsettled, active and storm days respectively. A statistically significant inverse relationship between GMA and the frequency of ICD therapies was identified, with the most pronounced difference between Level I and Level IV days (p < .001 for shocks, p = .008 for shocks + ATP). Conclusion In a large scale cohort analysis, ICD therapies were delivered less frequently on days of higher GMA, confirming the previous pilot data and suggesting that higher GMA does not pose an increased risk of arrhythmias using ICD therapies as a surrogate marker. Further studies are needed to gain an in-depth understanding of the underlying mechanisms. PMID:25659238

  9. Geophysical variables and behavior: XCVIII. Ambient geomagnetic activity and experiences of "memories": interactions with sex and implications for receptive psi experiences.

    PubMed

    Persinger, M A

    2002-06-01

    During 96 nonsequential days over a 3-yr. period, a total of 53 men and 86 women were exposed only once for 30 min. to transcerebral, weak complex magnetic fields while they sat alone within a quiet chamber. They were asked to record the frequency of specific experiences after the exposure was completed. There was a significant interaction between sex and global geomagnetic activity for the incidence of experiences attributed to memories. Women reported more experiences attributed to "childhood memories" when geomagnetic activity was less than 20 nT, while men reported more of these experiences when the activity was more than 20 nT. Re-analyses of a database of "paranormal experiences" reported by 395 separate individuals over a 100-yr. period indicated that more men than women reported "precognitive experiences" on days the geomagnetic activity was above 20 nT while women reported such experiences if the geomagnetic activity was below 20 nT. These results suggest that these experiences, be they veridical or illusory, may be influenced by global geomagnetic activity that affect the neuroelectrical or neurochemical processes associated with memory consolidation or the attribution of the serial order of experiences during retrieval. PMID:12186249

  10. Bracing for the geomagnetic storms

    SciTech Connect

    Kappenman, J.G. ); Albertson, V.D. )

    1990-03-01

    The authors discuss the impact of geomagnetic storms on utility transmission networks. The effects of a recent storm on the Hydro-Quebec transmission system are described in detail. Research into geomagnetic disturbance prediction is discussed. In coming months, geomagnetic field activity will be high as it builds toward a peak, the 22nd since reliable records of the phenomenon began in the mid-1700s. The peaks come in roughly 11-year cycles, and the next is expected later this year or early in 1991. The solar activity has so far risen at one of the fastest rates ever recorded, and solar forecasters expect cycle 22 to have unusually high activity levels.

  11. Dependence of plasmaspheric hiss on solar wind parameters and geomagnetic activity and modeling of its global distribution

    NASA Astrophysics Data System (ADS)

    Kim, Kyung-Chan; Lee, Dae-Young; Shprits, Yuri

    2015-02-01

    Accurate knowledge of the global distribution of plasmaspheric hiss is essential for the radiation belt modeling because it provides a direct link to understanding the radiation belt loss in the slot region. In this paper, we study the dependence of hiss activity on solar wind parameters and geomagnetic activity indices using Time History of Events and Macroscale Interactions during Substorms hiss measurements made from 1 July 2008 to 30 June 2012 based on a correlation analysis. We find that hiss amplitudes are well correlated with the preceding solar wind speed VSW, interplanetary magnetic field (IMF) BZ, and interplanetary electric field (IEF) EY with delay times of 5-6 h for VSW and 3-4 h for IMF BZ and IEF EY, while the best correlation with the geomagnetic indices, AE, Kp, and SYM-H, occurs at a delay time of 2-3 h for AE and SYM-H and 3-4 h for Kp. Of the solar wind parameters, the dawn-to-dusk component of IEF EY yields the best correlation with the variation of hiss wave. More interestingly, the global distribution of hiss waves shows a significant dependence on the VSW and IMF BZ: the most intense hiss region tends to occur at prenoon sector for a more southward IMF BZ, while the tendency is opposite with increasing VSW. This implies different origins of hiss activity. Also, we employ an artificial neural network technique to develop models of the global distribution of hiss amplitudes based on the solar wind parameters and geomagnetic indices. The solely solar wind parameter-based model generally results in a higher correlation between the measured and modeled hiss amplitudes than any other models based on the geomagnetic indices. Finally, we use the solar wind parameter-based model to investigate hiss activity during storm events by distinguishing between coronal mass ejection-driven storms and corotating interaction region-driven storms. The result shows that in spite of the differences in the behavior of solar wind parameters between the two storm

  12. Periodic variation in the geomagnetic activity - A study based on the Ap index

    NASA Technical Reports Server (NTRS)

    De Gonzalez, Alicia L. C.; Gonzalez, Walter D.; Dutra, Severino L. G.; Tsurutani, Bruce T.

    1993-01-01

    The monthly and daily samples of the Ap index for the interval from 1932 through 1982 were studied using the power spectrum technique. Results obtained for Bartel's period (about 27 days), the semiannual period, the dual-peak solar cycle distribution of geomagnetic storms, and certain other medium-scale periodicities are examined in detail. In addition, results on the cumulative occurrence number of storms per decade as a function of the Ap and Dst indices for the storm are presented.

  13. A Direct Relation Between Solar Activity Variability and Geomagnetic Disturbances During The Past 130 Years

    NASA Astrophysics Data System (ADS)

    Liszka, L.; Lundin, R.; Lundstedt, H.

    We use a Principal Component (PC) analysis technique to study the long term vari- ability in the frequency domain of the sunspot numbers, often referred to as the Wolf- numbers. The long-term variation of the Wolf-number frequency is compared with the long term variation of the geomagnetic AA-index during the past 130 years. We find a close correlation between the long periodic (20-128 days) variation of the Wolf- number (denoted LFW) and the AA-index. This suggests the LFW can be used as a proxy for global geomagnetic disturbances. Similarly, Lockwood et al (1999) found that the geomagnetic AA-index and the solar magnetic flux is well correlated. There- fore, the LFW is likely to be a useful proxy for the solar magnetic flux, ie periods with enhanced LFW is connected with enhanced solar magnetic flux. An important finding is that the Sun has experienced a substantial change in the sunspot frequence domain during the last 150 years, - the high-frequency component (period 2-4 days) decreas- ing , the low-frequency component (period 20-128 days) increasing. These changes must have an impact on the innermost planets in our solar system, the extent still to be determined. A potential result of the long-term solar magnetic flux variability inferred from the LFW is a modification of the global climate as suggested by Svensmark and Friis-Christensen (1997).

  14. Study of geomagnetic storms, solar flares, and centers of activity in 1976, the year between solar activity cycles 20 and 21

    SciTech Connect

    Hedeman, E.R.; Prince, H.D.

    1980-09-02

    Solar and geophysical circumstances prior to the 34 principal geomagnetic storms in 1976 have been evaluated. In this year of sun spot minima, 21 of the storms were unambiguously classified as sequential. For 7 of the storms prior flares may have played a role. Six of the storms remain as 'problem' situations. The 3 most severe storms in 1976 were associated with the 3 flares in 1976 with Comprehensive Flare Indices > or = 10. Inspection of plots of daily geomagnetic character figures suggest that at least 6 different sequences contributed to the geomagnetic disturbance in 1976. Relationships were sought between inferred coronal holes and the observed locations of significant centers of activity as the possible origins of the sequential storm particles. All of the major recurrent storm sequences in 1976 apparently had at their roots significant centers of activity that could have been near the perimeters of deduced associated coronal holes. The sequential storms occurred as the active regions were dying and continued long after all optical events of the active regions had disappeared.

  15. A re-evaluation of the Italian historical geomagnetic catalogue: implications for paleomagnetic dating at active Italian volcanoes

    NASA Astrophysics Data System (ADS)

    D'ajello Caracciolo, F.; Pignatelli, A.; Speranza, F.; Meloni, A.

    2011-12-01

    Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleo)secular variation ((P)SV) are available. To this end, we re-evaluate the whole Italian geomagnetic directional data set, consisting of 833 and 696 declination and inclination (respectively) measurements carried out since 1640 AD at several localities. All directions were relocated via virtual geomagnetic pole method to Stromboli (38.8°N, 15.2°E), rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method) by French data (for period 1670-1789), and by nearby Italian sites/years (for periods 1640-1657 and 1790-1962). Using post-1825 declination values, we obtain a 0.46±0.19 °/yr westward drift of the geomagnetic field for Italy. The original observation years were modified, considering such drift value, to derive at a drift-corrected relocated dataset. Both datasets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000) and Pavon-Carrasco et al. (2009). However, the drift-corrected dataset minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933-1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated datasets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. The curve comparison suggests that both available field models yields the best available SV curve to perform paleomagnetic dating of 1600-1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the 19th century. For the 20th century, the global model by Jackson et al. (2000) yields more accurate

  16. Dominant modes of relationship between U.S. temperature and geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Prohaska, J. T.; Willett, H. C.

    1983-01-01

    Eigen-analysis is applied to a matrix of cross-correlation coefficients between the geomagnetic aa-index for 0 to 23-yr lag and the monthly mean temperature at 32 United States stations. About 75 percent of the relationship between the two fields is contained in three dominant modes. A secular trend (about 90 yr) and two 11-yr cycles dominate the mode time series. The month-to-month changes in the temperature anomaly patterns indicate a slow eddy-like motion to the east of the Continental Divide for all three dominant modes.

  17. Observations of intense ULF pulsation activity near the geomagnetic equator during quiet times

    NASA Technical Reports Server (NTRS)

    Engebretson, M. J.; Zanetti, L. J.; Potemra, T. A.; Klumpar, D. M.; Strangeway, R. J.; Acuna, M. H.

    1988-01-01

    This paper analyzes observations, made by particle and field instruments on the AMPTE CCE satellite, of intense ULF pulsations in the earth's magnetosphere near the geomagnetic equator. These pulsations were observed during magnetically quiet periods in regions characterized by intense fluxes of warm strongly trapped light ions, predominantly H(+), and often with streaming low-energy plasma. The strong latitudinal localization of these pulsations is interpreted to be due to equatorial mass loading or to partial reflection of Alfven wave energy by latitudinal gradients in plasma density. Possible sources of wave energy for these events are discussed.

  18. Near-Earth Solar Wind Flows and Related Geomagnetic Activity During more than Four Solar Cycles (1963-2011)

    NASA Technical Reports Server (NTRS)

    Richardson, Ian G.; Cane, Hilary V.

    2012-01-01

    In past studies, we classified the near-Earth solar wind into three basic flow types based on inspection of solar wind plasma and magnetic field parameters in the OMNI database and additional data (e.g., geomagnetic indices, energetic particle, and cosmic ray observations). These flow types are: (1) High-speed streams associated with coronal holes at the Sun, (2) Slow, interstream solar wind, and (3) Transient flows originating with coronal mass ejections at the Sun, including interplanetary coronal mass ejections and the associated upstream shocks and post-shock regions. The solar wind classification in these previous studies commenced with observations in 1972. In the present study, as well as updating this classification to the end of 2011, we have extended the classification back to 1963, the beginning of near-Earth solar wind observations, thereby encompassing the complete solar cycles 20 to 23 and the ascending phase of cycle 24. We discuss the cycle-to-cycle variations in near-Earth solar wind structures and l1e related geomagnetic activity over more than four solar cycles, updating some of the results of our earlier studies.

  19. Two substorm studies of relations between westward electric fields in the outer plasmasphere, auroral activity, and geomagnetic perturbations

    NASA Technical Reports Server (NTRS)

    Carpenter, D. L.; Akasofu, S.

    1972-01-01

    Temporal variations of the westward component of the magnetospheric convection electric field in the outer plasmasphere were compared to auroral activity near L = 7, and to variations in the geomagnetic field at middle and high latitudes. The substorms occurred on July 29, 1965 near 0530 UT and on August 20, 1965 near 0730 UT. The results on westward electric field E(w) were obtained by the whistler method using data from Eights, Antarctica (L is approximately 4). All sky camera records were obtained from Byrd, Antarctica, (L is approximately 7), located within about 1 hour of Eights in magnetic local time. It was found that E(w) within the outer plasmasphere increased rapidly to substorm levels about the time of auroral expansion at nearby longitudes. This behavior is shown to differ from results on E(w) from balloons, which show E(w) reaching enhanced levels prior to the expansion. A close temporal relation was found between the rapid, substorm associated increases in E(w) and a well known type of nightside geomagnetic perturbation. Particularly well defined was the correlation of E(w) rise and a large deviation of the D component at middle latitudes.

  20. Influence of geomagnetic activity and atmospheric pressure on human arterial pressure during the solar cycle 24

    NASA Astrophysics Data System (ADS)

    Azcárate, T.; Mendoza, B.; Levi, J. R.

    2016-11-01

    We performed a study of the systolic (SBP) and diastolic (DBP) arterial blood pressure behavior under natural variables such as the atmospheric pressure (AtmP) and the horizontal geomagnetic field component (H). We worked with a sample of 304 healthy normotense volunteers, 152 men and 152 women, with ages between 18 and 84 years in Mexico City during the period 2008-2014, corresponding to the minimum, ascending and maximum phases of the solar cycle 24. The data was divided by gender, age and day/night cycle. We studied the time series using three methods: Correlations, bivariate and superposed epochs (within a window of three days around the day of occurrence of a geomagnetic storm) analysis, between the SBP and DBP and the natural variables (AtmP and H). The correlation analysis indicated correlation between the SBP and DBP and AtmP and H, being the largest during the night. Furthermore, the correlation and bivariate analysis showed that the largest correlations are between the SBP and DBP and the AtmP. The superposed epoch analysis found that the largest number of significant SBP and DBP changes occurred for women. Finally, the blood pressure changes are larger during the solar minimum and ascending solar cycle phases than during the solar maximum; the storms of the minimum were more intense than those of the maximum and this could be the reason of behavior of the blood pressure changes along the solar cycle.

  1. On the slow time geomagnetic field modulation of galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Okpala, Kingsley

    2016-07-01

    Cosmic rays of galactic origin are modulated by both heliospheric and geomagnetic conditions. The mutual (and mutually exclusive) contribution of both heliospheric and geomagnetic conditions to galactic cosmic rays (GCR) modulation is still an open question. While the rapid-time association of the galactic cosmic ray variation with different heliophysical and geophysical phenomena has been well studied, not so much attention has been paid to slow-time variations especially with regards to local effects. In this work, we employed monthly means of cosmic ray count rates from two mid latitude (Hermanus and Rome), and two higher latitude (Inuvik and Oulu) neutron monitors (NM), and compared their variability with geomagnetic stations that are in close proximity to the NMs. The data spans 1966 to 2008 and covers four (4) solar cycles. The difference (DeltaCR)between the mean count rate of all days and the mean of the five quietest days for each month was compared with the Dst-related disturbance (DeltaH) derived from the nearby geomagnetic stations. Zeroth- and First- correlation between the cosmic ray parameters and geomagnetic parameters was performed to ascertain statistical association and test for spurious association. Our results show that solar activity is generally strongly correlated (>0.75) with mean strength of GCR count rate and geomagnetic field during individual solar cycles. The correlation between mean strength of cosmic ray intensity and Geomagnetic field strength is spurious and is basically moderated by the solar activity. The signature of convection driven disturbances at high latitude geomagnetic stations was evident during the declining phase of the solar cycles close to the solar minimum. The absence of this feature in the slow-time varying cosmic ray count rates in all stations, and especially in the mid latitude geomagnetic stations suggest that the local geomagnetic disturbance contributes much less in modulating the cosmic ray flux.

  2. The effects of geomagnetic activity in biological phenomena and physico-chemical processes as observed in the laboratories.

    NASA Astrophysics Data System (ADS)

    Vladimirskij, B. M.

    A short review is given of the most important Soviet results of the investigations of geomagnetic activity effects on biological and physico-chemical phenomena. The main topics are: 1. The presence of well known geophysical periods in some organisms (biological rhythms). 2. The correlations of some biological indexes and water solution's parameters with the sector structure of the IMF. 3. Cosmophysical origin of "macroscopic fluctuations". 4. The influence of magnetic disturbances (the variations of solar activity) upon precise measurements. All these correlations might be interpreted as the influence upon the systems of variations in the electromagnetic background fields of VLF-ELF range. Such variations are important environment factors which have to be taken into account in modern ecology.

  3. Geomagnetic activity and north-south asymmetry of cosmic rays circa 1 GV. Final report, 1 March 1977-30 September 1984

    SciTech Connect

    Ely, J.T.; Huang, T.C.

    1986-09-26

    Various features of solar-sector synchronous modulations of the particulate cosmic radiation reaching the earth's atmosphere have been studied using satellite and surface data. The flux in the broad maximum of the galactic cosmic-ray differential spectrum (near 1 GV rigidity) exhibits an intermittent north-south asymmetry in mid and high geomagnetic latitudes. This modulation exhibited a strong association with the geomagnetic disturbance index and interplanetary magnetic field direction during the 1964 and 1965 years of sunspot minimum. Such correlations are consistent with the predictions of a theory that attributes the north south asymmetry to reconnection of the interplanetary and geomagnetic fields. This finding is also consistent with suggestions that the solar-activity influence on atmospheric processes may be mediated by the resulting modulations of upper tropospheric ionization.

  4. Observations of large-scale plasma convection in the magnetosphere with respect to the geomagnetic activity level

    NASA Astrophysics Data System (ADS)

    Stepanov, A. E.; Khalipov, V. L.; Kotova, G. A.; Zabolotskii, M. S.; Golikov, I. A.

    2016-03-01

    The data of the ionospheric observations (the daily f plots) at the Yakutsk meridional chain of ionosondes (Yakutsk-Zhigansk-Batagai-Tixie Bay) with sharp decreases (breaks) in the critical frequency of the regular ionospheric F2 layer ( foF2) are considered. The data for 1968-1983 were analyzed, and the statistics of the foF2 break observations, which indicate that these breaks are mainly registered in equinoctial months and in afternoon and evening hours under moderately disturbed geomagnetic conditions, are presented. Calculations performed using the prognostic model of the high-latitude ionosphere indicate that the critical frequency break position coincides with the equatorial boundary of large-scale plasma convection in the dusk MLT sector.

  5. [Influences of solar and geomagnetic activity on health status of people with various nosological forms of diseases].

    PubMed

    Gadzhiev, G D; Rakhmatulin, R A

    2013-01-01

    Statistical analysis of correlation between heliogeophysical factors and a symptom of the various forms of diseases (based on statistical data on disease of the personnel of Irkutsk Scientific Centre, RAS) has been studied. It is shown that geomagnetic storms influence vegetative regulation of a cardiac rhythm and vascular tone. The most serious consequences of such influence can mainly be observed in the persons suffering from diseases of the cardiovascular system (consequences of myocardium attack, brain strokes, cardiac rhythm disorders); being in a condition of additional stress, mainly with vegetovascular and hypertensic crises; having mental diseases; and subject to aggravations of general diseases (chronic inflammatory diseases of gynecological, musculoskeletal, urinary excretory, bronchopulmonary systems, and systems of digestive organs). PMID:24455893

  6. Tree-stem diameter fluctuates with the lunar tides and perhaps with geomagnetic activity.

    PubMed

    Barlow, Peter W; Mikulecký, Miroslav; Střeštík, Jaroslav

    2010-11-01

    Our initial objective has been to examine the suggestion of Zürcher et al. (Nature 392:665–666, 1998) that the naturally occurring variations in stem diameter of two experimental trees of Picea alba were related to near simultaneous variations in the lunisolar tidal acceleration. The relationship was positive: Lunar peaks were roughly synchronous with stem diameter peaks. To extend the investigation of this putative relationship, additional data on stem diameter variations from six other tree species were gathered from published literature. Sixteen sets of data were analysed retrospectively using graphical representations as well as cosinor analysis, statistical cross-correlation and cross-spectral analysis, together with estimated values of the lunisolar tidal acceleration corresponding to the sites, dates and times of collection of the biological data. Positive relationships were revealed between the daily variations of stem diameter and the variations of the lunisolar tidal acceleration. Although this relationship could be mediated by a 24.8-h lunar rhythm, the presence of a solar rhythm of 24.0 h could not be ruled out. Studies of transpiration in two of the observed trees indicated that although this variable was not linked to stem diameter variation, it might also be subject to lunisolar gravitational regulation. In three cases, the geomagnetic Thule index showed a weak but reciprocal relationship with stem diameter variation, as well as a positive relationship with the lunisolar tidal force. In conclusion, it seems that lunar gravity alone could influence stem diameter variation and that, under certain circumstances, additional regulation may come from the geomagnetic flux. PMID:20393759

  7. Tree-stem diameter fluctuates with the lunar tides and perhaps with geomagnetic activity.

    PubMed

    Barlow, Peter W; Mikulecký, Miroslav; Střeštík, Jaroslav

    2010-11-01

    Our initial objective has been to examine the suggestion of Zürcher et al. (Nature 392:665–666, 1998) that the naturally occurring variations in stem diameter of two experimental trees of Picea alba were related to near simultaneous variations in the lunisolar tidal acceleration. The relationship was positive: Lunar peaks were roughly synchronous with stem diameter peaks. To extend the investigation of this putative relationship, additional data on stem diameter variations from six other tree species were gathered from published literature. Sixteen sets of data were analysed retrospectively using graphical representations as well as cosinor analysis, statistical cross-correlation and cross-spectral analysis, together with estimated values of the lunisolar tidal acceleration corresponding to the sites, dates and times of collection of the biological data. Positive relationships were revealed between the daily variations of stem diameter and the variations of the lunisolar tidal acceleration. Although this relationship could be mediated by a 24.8-h lunar rhythm, the presence of a solar rhythm of 24.0 h could not be ruled out. Studies of transpiration in two of the observed trees indicated that although this variable was not linked to stem diameter variation, it might also be subject to lunisolar gravitational regulation. In three cases, the geomagnetic Thule index showed a weak but reciprocal relationship with stem diameter variation, as well as a positive relationship with the lunisolar tidal force. In conclusion, it seems that lunar gravity alone could influence stem diameter variation and that, under certain circumstances, additional regulation may come from the geomagnetic flux.

  8. On the uniqueness of linear moving-average filters for the solar wind-auroral geomagnetic activity coupling

    NASA Technical Reports Server (NTRS)

    Vassiliadis, D.; Klimas, A. J.

    1995-01-01

    The relation between the solar wind input to the magetosphere, VB(sub South), and the auroral geomagnetic index AL is modeled with two linear moving-average filtering methods: linear prediction filters and a driven harmonic oscillator in the form of an electric circuit. Although the response of the three-parameter oscillator is simpler than the filter's, the methods yield similar linear timescales and values of the prediction-observation correlation and the prediction Chi(exp 2). Further the filter responses obtained by the two methods are similar in their long-term features. In these aspects the circuit model is equivalent to linear prediction filtering. This poses the question of uniqueness and proper interpretation of detailed features of the filters such as response peaks. Finally, the variation of timescales and filter responses with the AL activity level is discussed.

  9. Consistent QBO-dependent effect of geomagnetic activity on the Northern Annular Mode during the 20th century

    NASA Astrophysics Data System (ADS)

    Maliniemi, Ville; Asikainen, Timo; Mursula, Kalevi

    2016-04-01

    Several earlier studies have shown that geomagnetic activity (GA), as a proxy for energetic particle precipitation into the atmosphere, affects the winter-time Northern Annular Mode (NAM), which is the dominant circulation pattern in the northern hemisphere during winter. It has also been found that the quasi-biennial oscillation (QBO) modulates the relationship between GA and NAM. However, some of the earlier studies on this QBO modulation have been mutually conflicting, with some studies suggesting a stronger positive relation in the easterly phase of the QBO, while other studies suggest a stronger positive relation in the westerly phase of the QBO. Here we study the QBO-GA-NAM relationship using a QBO reconstruction covering the whole 20th century. We find that the QBO modulation of the GA-NAM relation is temporally variable, which explains the earlier, seemingly differing results. Positive GA-NAM relation is found to be valid in the easterly QBO phase at 30 hPa during the whole 20th century. We also find that the QBO at 30 hPa represents the Holton-Tan relation for the surface circulation better than QBO at 50 hPa, and that the Holton-Tan relation is only observed during early/mid winter, while an anti-Holton-Tan relation is found in the late winter for strong geomagnetic activity. These results emphasize the variable but systematic response of NAM to energetic particle precipitation during the entire 20th century, and underline the importance of considering the preconditioning of the atmosphere when studying the solar-related effects upon climate.

  10. On the Relationship Between Global Land-Ocean Temperature and Various Descriptors of Solar-Geomagnetic Activity and Climate

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2014-01-01

    Examined are sunspot cycle- (SC-) length averages of the annual January-December values of the Global Land-Ocean Temperature Index () in relation to SC-length averages of annual values of various descriptors of solar-geomagnetic activity and climate, incorporating lags of 0-5 yr. For the overall interval SC12-SC23, the is inferred to correlate best against the parameter incorporating lag = 5 yr, where the parameter refers to the resultant aa value having removed that portion of the annual aa average value due to the yearly variation of sunspot number (SSN). The inferred correlation between the and is statistically important at confidence level cl > 99.9%, having a coefficient of linear correlation r = 0.865 and standard error of estimate se = 0.149 degC. Excluding the most recent cycles SC22 and SC23, the inferred correlation is stronger, having r = 0.969 and se = 0.048 degC. With respect to the overall trend in the , which has been upwards towards warmer temperatures since SC12 (1878-1888), solar-geomagnetic activity parameters are now trending downwards (since SC19). For SC20-SC23, in contrast, comparison of the against SC-length averages of the annual value of the Mauna Loa carbon dioxide () index is found to be highly statistically important (cl >> 99.9%), having r = 0.9994 and se = 0.012 degC for lag = 2 yr. On the basis of the inferred preferential linear correlation between the and , the current ongoing SC24 is inferred to have warmer than was seen in SC23 (i.e., >0.526 degC), probably in excess of 0.68 degC (relative to the 1951-1980 base period).

  11. Wavelet analysis of the singular spectral reconstructed time series to study the imprints of solar-ENSO-geomagnetic activity on Indian climate

    NASA Astrophysics Data System (ADS)

    Lakshmi Sunkara, Sri; Krishna Tiwari, Rama

    2016-09-01

    To study the imprints of the solar-ENSO-geomagnetic activity on the Indian subcontinent, we have applied singular spectral analysis (SSA) and wavelet analysis to the tree-ring temperature variability record from the Western Himalayas. Other data used in the present study are the solar sunspot number (SSN), geomagnetic indices (aa index), and the Southern Oscillation Index (SOI) for the common time period of 1876-2000. Both SSA and wavelet spectral analyses reveal the presence of 5-7-year short-term ENSO variations and the 11-year solar cycle, indicating the possible combined influences of solar-geomagnetic activities and ENSO on the Indian temperature. Another prominent signal corresponding to 33-year periodicity in the tree-ring record suggests the Sun-temperature variability link probably induced by changes in the basic state of the Earth's atmosphere. In order to complement the above findings, we performed a wavelet analysis of SSA reconstructed time series, which agrees well with our earlier results and increases the signal-to-noise ratio, thereby showing the strong influence of solar-geomagnetic activity and ENSO throughout the entire period. The solar flares are considered responsible for causing the atmospheric circulation patterns. The net effect of solar-geomagnetic processes on the temperature record might suggest counteracting influences on shorter (about 5-6-year) and longer (about 11-12-year) timescales. The present analyses suggest that the influence of solar activities on the Indian temperature variability operates in part indirectly through coupling of ENSO on multilateral timescales. The analyses, hence, provide credible evidence of teleconnections of tropical Pacific climatic variability and Indian climate ranging from inter-annual to decadal timescales and also suggest the possible role of exogenic triggering in reorganizing the global Earth-ocean-atmospheric systems.

  12. Effect of possible passage through Halley's magnetic tail on geomagnetic activity

    SciTech Connect

    Russell, C.T.; Phillips, J.L. ); Fedder, J.A. ); Allen, J.H.; Morris, L. ); Craig, R.A. )

    1987-10-01

    The geomagnetic aa index shows that a nonrecurrent magnetic disturbance occurred in May 1910 near the time of the passage of comet Halley through inferior conjunction. Examination of ground-based magnetograms from May 18 to 20, 1910, shows that this disturbance consisted, in part, of a negative bay of the depth expected if the magnetopause currents had ceased. The duration of this bay could have been caused by the Earth's entry into a cometary tail lobe width of about 10{degrees} km. Other features during this period suggest that the Earth may have also earlier grazed the other lobe of the cometary tail and passed through the plasma sheet. If this interpretation is true, the entire region of interaction was about 6 {times} 10{sup 6} km wide 24 {times} 10{sup 6} km downstream from the nucleus. MHD computer simulations of the solar wind interaction with Halley to 7 {times} 10{sup 6} km downstream are consistent with the inferred tail properties. The fact that the signature of the interaction was observed earlier than expected suggests that momentum transfer occurred from the comet to the solar wind over a very extended region of space around the comet. If this momentum transfer deflected the solar wind flow with the 45-km/s transverse velocity of the comet, the observed timing would be consistent with an initially radially flowing solar wind of 750 km/s or a solar wind flow 4{degrees} from the radial of 500 km/s.

  13. Auroral activities observed by SNPP VIIRS day/night band during a long period geomagnetic storm event on April 29-30, 2014

    NASA Astrophysics Data System (ADS)

    Shao, Xi; Cao, Changyong; Liu, Tung-chang; Zhang, Bin; Wang, Wenhui; Fung, Shing F.

    2015-10-01

    The Day/Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advancement in night time imaging capabilities. The DNB senses radiance that can span 7 orders of magnitude in one panchromatic (0.5-0.9 μm) reflective solar band and provides imagery of clouds and other Earth features over illumination levels ranging from full sunlight to quarter moon. When the satellite passes through the day-night terminator, the DNB sensor is affected by stray light due to solar illumination on the instrument. With the implementation of stray light correction, stray light-corrected DNB images enable the observation of aurora occurred in the high latitude regions during geomagnetic storms. In this paper, DNB observations of auroral activities are analyzed during a long period (> 20 hours) of geomagnetic storm event occurred on Apr. 29-30, 2014. The storm event has the Bz component of interplanetary magnetic field (IMF) pointing southward for more than 20 hours. During this event, the geomagnetic storm index Dst reached -67 nT and the geomagnetic auroral electrojet (AE) index increased and reached as high as 1200 nT with large amplitude fluctuations. The event occurred during new moon period and DNB observation has minimum moon light contamination. During this event, auroras are observed by DNB for each orbital pass on the night side (~local time 1:30am) in the southern hemisphere. DNB radiance data are processed to identify regions of aurora during each orbital pass. The evolution of aurora is characterized with time series of the poleward and equatorward boundary of aurora, area, peak radiance and total light emission of the aurora in DNB observation. These characteristic parameters are correlated with solar wind and geomagnetic index parameters. It is found that the evolution of total area-integrated radiance of auroral region over the southern hemisphere correlated well with the ground geomagnetic AE index with correlation

  14. Modeling of geomagnetic activity due to passage of different structures and features of high speed streams

    NASA Astrophysics Data System (ADS)

    Mustajab, Fainana

    2016-07-01

    The modeling of terrestrial environment and relative geoeffectiveness due to high speed streams of different type and also compare their geoeffectiveness due to fine structures associated with streams, for example i) streams with different speed, ii) streams with different durations, iii) streams from different solar source and iv) associated fine structures. We also observed high speed streams during 1996 to 2011, and divided them into convenient groups based on their i) speed, ii) durations, iii) solar sources and iv) Dst groups. Performed them method of superposed-epoch analysis and other some statistical-analysis and correlation analysis between geomagnetic index Dst and plasma/field parameters during for both main phase and recovery phase. Streams having the passage duration ranging from 4.5 days to 10.5 days is 59% while other groups, having passage duration <4.5 days and > 10.5 days, contribute only near about 13%. When we observe group according to speed of streams, 30% of high speed streams are having the speed >650km/s and other groups are near about equally distributed in the range 400km/s to 650km/s. Out of 575 high speed streams, 45% streams are caused by single coronal hole, 20% due to multiple coronal hole, 24% by compound i.e: due to coronal hole and coronal mass ejections and only 10% from coronal mass ejections. The streams which are responsible for quiet, weak, moderate storms are nearly equal and only 12% streams cause severe storms. Dst gives best correlation with V(km/s) and BVres to the power 2 (x10res to the power 6) for over all storm time. B(nT) and BV(x10res to the power 3) represent good correlation with Dst during recovery phase duration for the speed groups. I observed the percentage of quiet storms decreases with increasing speed of streams. Near about equal percentage of weak storm are observed in each set of speed of stream. 17% moderate storms are found to contribute for the speed range 400-550km/s and ≈33% contribution is

  15. Wavelet analysis of the singular spectral reconstructed time series to study the imprints of Solar-ENSO-Geomagnetic activity on Indian climate

    NASA Astrophysics Data System (ADS)

    Sri Lakshmi, S.; Tiwari, R. K.

    2015-09-01

    In order to study the imprints of solar-ENSO-geomagnetic activity on the Indian Subcontinent, we have applied the Singular Spectral Analysis (SSA) and wavelet analysis to the tree ring temperature variability record from the western Himalayas. The data used in the present study are the Solar Sunspot Number (SSN), Geomagnetic Indices (aa Index), Southern Oscillation Index (SOI) and tree ring temperature record from western Himalayas (WH), for the period of 1876-2000. The SSA and wavelet spectra reveal the presence of 5 years short term ENSO variations to 11 year solar cycle indicating the influence of both the solar-geomagnetic and ENSO imprints in the tree ring data. The presence of 33-year cycle periodicity suggests the Sun-temperature variability probably involving the induced changes in the basic state of the atmosphere. Our wavelet analysis for the SSA reconstructed time series agrees with our previous results and also enhance the amplitude of the signals by removing the noise and showing a strong influence of solar-geomagnetic and ENSO patterns throughout the record. The solar flares are considered to be responsible for cause in the circulation patterns in the atmosphere. The net effect of solar-geomagnetic processes on temperature record thus appears to be the result of counteracting influences on shorter (about 5-6 years) and longer (about 11-12 years) time scales. The present analysis thus suggests that the influence of solar processes on Indian temperature variability operates in part indirectly through ENSO, but on more than one time scale. The analyses hence provides credible evidence for teleconnections of tropical pacific climatic variability with Indian climate ranging from interannual-decadal time scales and also demonstrate the possible role of exogenic triggering in reorganizing the global earth-ocean-atmospheric systems.

  16. The national geomagnetic initiative

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Earth's magnetic field, through its variability over a spectrum of spatial and temporal scales, contains fundamental information on the solid Earth and geospace environment (the latter comprising the atmosphere, ionosphere, and magnetosphere). Integrated studies of the geomagnetic field have the potential to address a wide range of important processes in the deep mantle and core, asthenosphere, lithosphere, oceans, and the solar-terrestrial environment. These studies have direct applications to important societal problems, including resource assessment and exploration, natural hazard mitigation, safe navigation, and the maintenance and survivability of communications and power systems on the ground and in space. Studies of the Earth's magnetic field are supported by a variety of federal and state agencies as well as by private industry. Both basic and applied research is presently supported by several federal agencies, including the National Science Foundation (NSF), U.S. Geological Survey (USGS), U.S. Department of Energy (DOE), National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and U.S. Department of Defense (DOD) (through the Navy, Air Force, and Defense Mapping Agency). Although each agency has a unique, well-defined mission in geomagnetic studies, many areas of interest overlap. For example, NASA, the Navy, and USGS collaborate closely in the development of main field reference models. NASA, NSF, and the Air Force collaborate in space physics. These interagency linkages need to be strengthened. Over the past decade, new opportunities for fundamental advances in geomagnetic research have emerged as a result of three factors: well-posed, first-order scientific questions; increased interrelation of research activities dealing with geomagnetic phenomena; and recent developments in technology. These new opportunities can be exploited through a national geomagnetic initiative to define objectives and

  17. Introduction to Geomagnetic Fields: Second Edition

    NASA Astrophysics Data System (ADS)

    Campbell, Wallace H.

    2003-04-01

    Preface; Acknowledgements; 1. The Earth's main field; 2. Quiet-time field variations and dynamo currents; 3. Solar-terrestrial activity; 4. Measurement methods; 5. Applications; Appendix A: mathematical topics; Appendix B: geomagnetic organisations, services and bibliography; Appendix C: utility programs for geomagnetic fields; References; Index.

  18. Sources of Geomagnetic Activity during Nearly Three Solar Cycles (1972-2000)

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.; Cliver, E. W.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We examine the contributions of the principal solar wind components (corotating highspeed streams, slow solar wind, and transient structures, i.e., interplanetary coronal mass ejections (CMEs), shocks, and postshock flows) to averages of the aa geomagnetic index and the interplanetary magnetic field (IMF) strength in 1972-2000 during nearly three solar cycles. A prime motivation is to understand the influence of solar cycle variations in solar wind structure on long-term (e.g., approximately annual) averages of these parameters. We show that high-speed streams account for approximately two-thirds of long-term aa averages at solar minimum, while at solar maximum, structures associated with transients make the largest contribution (approx. 50%), though contributions from streams and slow solar wind continue to be present. Similarly, high-speed streams are the principal contributor (approx. 55%) to solar minimum averages of the IMF, while transient-related structures are the leading contributor (approx. 40%) at solar maximum. These differences between solar maximum and minimum reflect the changing structure of the near-ecliptic solar wind during the solar cycle. For minimum periods, the Earth is embedded in high-speed streams approx. 55% of the time versus approx. 35% for slow solar wind and approx. 10% for CME-associated structures, while at solar maximum, typical percentages are as follows: high-speed streams approx. 35%, slow solar wind approx. 30%, and CME-associated approx. 35%. These compositions show little cycle-to-cycle variation, at least for the interval considered in this paper. Despite the change in the occurrences of different types of solar wind over the solar cycle (and less significant changes from cycle to cycle), overall, variations in the averages of the aa index and IMF closely follow those in corotating streams. Considering solar cycle averages, we show that high-speed streams account for approx. 44%, approx. 48%, and approx. 40% of the solar

  19. Following solar activity with geomagnetic and cosmic-ray ground-based stations in the Iberian Peninsula region

    NASA Astrophysics Data System (ADS)

    Villasante-Marcos, Victor; José Blanco, Juan; Miquel Torta, Joan; Catalán, Manuel; Ribeiro, Paulo; Morozova, Anna; Tordesillas, José Manuel; Solé, Germán; Gomis-Moreno, Almudena

    2016-04-01

    The Iberian Peninsula is located in the South-West of Europe between 36°00' N and 43°47' N and between 9°29' W and 3°19' E. There are four Geomagnetic Observatories currently operative in this area devoted to the observation of the Earth's magnetic field: Observatori de l'Ebre (NE Spain); Observatorio de San Pablo de los Montes (central Spain); Observatorio de San Fernando (southern Spain); Observatório de Coimbra (central Portugal); plus another one, Observatorio de Güímar, in Tenerife (Canary Islands, Spain). There is also one neutron monitor located in Guadalajara (central Spain; 40°38' N, 3°9' W at 708 m asl) continuously measuring the arrival of cosmic rays to the Earth's surface. In this work we show combined observations of these six stations during events caused by solar activity. We analyze them looking for differences that could imply extremely local effects caused by the response of the Earth's magnetosphere and ionosphere to solar activity.

  20. Field-aligned neutral wind bias correction scheme for global ionospheric modeling at midlatitudes by assimilating FORMOSAT-3/COSMIC hmF2 data under geomagnetically quiet conditions

    NASA Astrophysics Data System (ADS)

    Sun, Yang-Yi; Matsuo, Tomoko; Maruyama, Naomi; Liu, Jann-Yenq

    2015-04-01

    This study demonstrates the usage of a data assimilation procedure, which ingests the FORMOSAT-3/COSMIC (F3/C) hmF2 observations to correct the model wind biases to enhance the capability of the new global Ionosphere Plasmasphere Electrodynamics (IPE) model under geomagnetically quiet conditions. The IPE model is built upon the field line interhemispheric plasma model with a realistic geomagnetic field model and empirical model drivers. The hmF2 observed by the F3/C radio occultation technique is utilized to adjust global thermospheric field-aligned neutral winds (i.e., a component of the thermospheric neutral wind parallel to the magnetic field) at midlatitudes according to a linear relationship between time differentials of the field-aligned wind and hmF2. The adjusted winds are further applied to drive the IPE model. The comparison of the modeled electron density with the observations of F3/C and ground-based GPS receivers at the 2012 March equinox suggests that the modeled electron density can be significantly improved in the midlatitude regions of the Southern Hemisphere, if the wind correction scheme is applied. Moreover, the F3/C observation, the IPE model, and the wind bias correction scheme are applied to study the 2012 Southern Hemisphere Midlatitude Summer Nighttime Anomaly (southern MSNA)/Weddell Sea Anomaly (WSA) event at December solstice for examining the role of the neutral winds in controlling the longitudinal variation of the southern MSNA/WSA behavior. With the help of the wind bias correction scheme, the IPE model better tracks the F3/C-observed eastward movement of the southern MSNA/WSA feature. The apparent eastward movement of the southern MSNA/WSA features in the local time coordinate is primarily caused by the longitudinal variation in the declination angle of the geomagnetic field that controls the field-aligned projection of both geographic meridional and zonal components of the neutral wind. Both the IPE simulations and the F3/C

  1. The geomagnetic activity influence on climatic characteristics of the troposphere and climate changes in the last century

    NASA Astrophysics Data System (ADS)

    Zherebtsov, Gely; Kovalenko, Vladimir; Molodykh, Sergey

    2010-05-01

    Mechanisms of solar activity effects on weather and climate have been discussed. Authors proposed a physical mechanism of solar activity effects on climatic characteristics and the atmospheric circulation through the atmospheric electricity. A model of the solar activity effect on climatic characteristics of the Earth's troposphere was elaborated on the basis of the mechanism under consideration. The model key concept is the heliogeophysical disturbance effect on the Earth climatic system's parameters, which influence energy flux going from the Earth to space in high-latitude areas. In accordance with this model, the atmospheric electricity parameters in the high latitudes depend on the solar activity; at the same time, they influence the altitude distribution of charged condensation nuclei in the troposphere, as well as the cloudiness formation and radiation balance and atmospheric circulation. When the solar activity increases, radiation cooling of high-latitude regions decreases, thermobaric field restructures, average meridian gradient of temperature between polar and equatorial regions decreases, defining the atmospheric circulation. Precipitation is a sensitive indicator of the atmospheric circulation change. NCEP/NCAR Reanalysis and CMAP data were used to analyze particularities and regularities of long-term variations in amount of precipitation in 1950-2007. Global decrease in amount of precipitation was found to dominate till late 1990s. It started increasing only 10 years ago. Peculiarities of distribution and long-term variations in amount of precipitation in different latitudes and longitudes were also considered. In the framework of the model considered, the analysis results are presented and discussed of regularities of variations in geomagnetic activity and troposphere thermobaric characteristics for 1900-2007. It is showed that a continuous increase of the Earth climatic system heat content has been observed from 1910 till now. Under the model, we

  2. Geomagnetic Disturbances Caused by Internal Atmospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Sonneman, G.

    1984-01-01

    It is commonly believed that geomagnetic disturbances are caused by external influences connected with the solar wind. The 27-day recurrence of perturbations seems to be a strong hint for this interaction. But frequently geomagnetic disturbances occur without any relation to sunspot numbers or radiowave fluxes. This was one of the reasons for introducing hypothetical M-regions on the Sun and their relation to solar wind activities. Only one half of the variance of the geomagnetic AL-index could be related to the solar wind. Therefore it is concluded that internal processes of the magnetosphere were responsible for additional geomagnetic activity. Arguments, which might lead to the suggestion of geomagnetic disturbances as being caused by internal atmospheric dynamics are discussed and a rather preliminary scenario of those processes is proposed.

  3. The effect of cosmic ray intensity variations and geomagnetic disturbances on the physiological state of aviators

    NASA Astrophysics Data System (ADS)

    Papailiou, M.; Mavromichalaki, H.; Kudela, K.; Stetiarova, J.; Dimitrova, S.; Giannaropoulou, E.

    2011-09-01

    Over the last few years various researches have reached the conclusion that cosmic ray variations and geomagnetic disturbances are related to the condition of the human physiological state. In this study medical data regarding 4018 Slovak aviators were analyzed in relation to daily variations of cosmic ray and geomagnetic activity. Specifically daily data concerning mean values of heart rate which were registered during the medical examinations of the Slovak aviators, were related to daily variations of cosmic ray intensity, as measured by the Neutron Monitor Station on Lomnicky Stit (http://neutronmonitor.ta3.sk/realtime.php3) and the high resolution neutron monitor database (http://www.nmdb.eu) and daily variations of Dst and Ap geomagnetic indices. All subjects were men in good health of age 18-60 yrs. This particular study refers to the time period from 1 January 1994 till 31 December 2002. Statistical methods were applied to establish a statistical significance of the effect of geomagnetic activity levels and cosmic ray intensity variations on the aforementioned physiological parameters for the whole group. The Pearson r-coefficients were calculated and the Analysis of Variance (ANOVA) method was applied to establish the statistical significance levels (p-values) of the effect of geomagnetic activity and cosmic ray intensity variations on heart rate up to three days before and three days after the respective events. Results show that there is an underlying effect of geomagnetic activity and cosmic ray intensity variations on the cardiovascular functionality.

  4. Radar observations of high-latitude lower-thermospheric and upper-mesospheric winds and their response to geomagnetic activity

    SciTech Connect

    Johnson, R.M.

    1987-01-01

    Observations made by the Chatanika, Alaska, incoherent scatter radar during the summer months of 1976 to 1081 are analyzed to obtain high resolution lower-thermospheric neutral winds. Average winds and their tidal components are presented and compared to previous observational and model results. Upper-mesospheric neutral-wind observations obtained by the Poke Flat, Alaska Mesosphere-Stratosphere-Troposphere (MST) radar during the summer months of 1980 to 1982 are investigated statistically for evidence of variations due to geomagnetic activity. Observation of upper-mesospheric neutral winds made during two energetic Solar Proton Events (SPEs) by the Poker Flat, MST radar are presented. These results allow the low-altitude limits of magnetospheric coupling to the neutral atmosphere to be determined. Lower-thermospheric neutral winds are coupled to the ion convection driven by typical magnetospheric forcing above about 100 km. Coupling to lower atmospheric levels does not occur except during intervals of extreme disturbance of the magnetosphere-ionosphere-thermosphere system which are also accompanied by dramatically increased ionization in the high-latitude mesosphere, such as SPEs.

  5. Impact of human activities on the geomagnetic field of Antarctica: a high resolution aeromagnetic survey over Mario Zucchelli Station.

    PubMed

    Armadillo, E; Bozzo, E; Gambetta, M; Rizzello, D

    2012-10-15

    Environmental protection of Antarctica is a fundamental principle of the Antarctic Treaty. Impact assessment and significance evaluation are due for every human activity on the remote continent. While chemical and biological contaminations are widely studied, very little is known about the electromagnetic pollution levels. In this frame, we have evaluated the significance of the impact of Mario Zucchelli Antarctic Station (Northern Victoria Land) on the local geomagnetic field. We have flown a high resolution aeromagnetic survey in drape mode at 320m over the Station, covering an area of 2km(2). The regional and the local field have been separated by a third order polynomial fitting. After the identification of the anthropic magnetic anomaly due to the Station, we have estimated the magnetic field at the ground level by downward continuation with an original inversion scheme regularized by a minimum gradient support functional to avoid high frequency noise effects. The resulting anthropic static magnetic field at ground extends up to 650m far from the Station and reaches a maximum peak to peak value of about 2800nT. This anthropic magnetic anomaly may interact with biological systems, raising the necessity to evaluate the significance of the static magnetic impact of human installations in order to protect the electromagnetic environment and the biota of Antarctica.

  6. Impact of human activities on the geomagnetic field of Antarctica: a high resolution aeromagnetic survey over Mario Zucchelli Station.

    PubMed

    Armadillo, E; Bozzo, E; Gambetta, M; Rizzello, D

    2012-10-15

    Environmental protection of Antarctica is a fundamental principle of the Antarctic Treaty. Impact assessment and significance evaluation are due for every human activity on the remote continent. While chemical and biological contaminations are widely studied, very little is known about the electromagnetic pollution levels. In this frame, we have evaluated the significance of the impact of Mario Zucchelli Antarctic Station (Northern Victoria Land) on the local geomagnetic field. We have flown a high resolution aeromagnetic survey in drape mode at 320m over the Station, covering an area of 2km(2). The regional and the local field have been separated by a third order polynomial fitting. After the identification of the anthropic magnetic anomaly due to the Station, we have estimated the magnetic field at the ground level by downward continuation with an original inversion scheme regularized by a minimum gradient support functional to avoid high frequency noise effects. The resulting anthropic static magnetic field at ground extends up to 650m far from the Station and reaches a maximum peak to peak value of about 2800nT. This anthropic magnetic anomaly may interact with biological systems, raising the necessity to evaluate the significance of the static magnetic impact of human installations in order to protect the electromagnetic environment and the biota of Antarctica. PMID:22706521

  7. New insights on geomagnetic storms from observations and modeling

    SciTech Connect

    Jordanova, Vania K

    2009-01-01

    Understanding the response at Earth of the Sun's varying energy output and forecasting geomagnetic activity is of central interest to space science, since intense geomagnetic storms may cause severe damages on technological systems and affect communications. Episodes of southward (Bzgeomagnetic conditions are associated either with coronal mass ejections (CMEs) and possess long and continuous negative IMF Bz excursions, or with high speed solar wind streams (HSS) whose geoeffectiveness is due to IMF Bz profiles fluctuating about zero with various amplitudes and duration. We show examples of ring current simulations during two geomagnetic storms representative of each interplanetary condition with our kinetic ring current atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. We find that periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. During the HSS-driven storm the convection potential is highly variable and causes small sporadic injections into the ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ring current injection penetrating to lower L shells and stronger ring current buildup.

  8. On the Relationship between Solar Wind Speed, Earthward-Directed Coronal Mass Ejections, Geomagnetic Activity, and the Sunspot Cycle Using 12-Month Moving Averages

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    For 1996 .2006 (cycle 23), 12-month moving averages of the aa geomagnetic index strongly correlate (r = 0.92) with 12-month moving averages of solar wind speed, and 12-month moving averages of the number of coronal mass ejections (CMEs) (halo and partial halo events) strongly correlate (r = 0.87) with 12-month moving averages of sunspot number. In particular, the minimum (15.8, September/October 1997) and maximum (38.0, August 2003) values of the aa geomagnetic index occur simultaneously with the minimum (376 km/s) and maximum (547 km/s) solar wind speeds, both being strongly correlated with the following recurrent component (due to high-speed streams). The large peak of aa geomagnetic activity in cycle 23, the largest on record, spans the interval late 2002 to mid 2004 and is associated with a decreased number of halo and partial halo CMEs, whereas the smaller secondary peak of early 2005 seems to be associated with a slight rebound in the number of halo and partial halo CMEs. Based on the observed aaM during the declining portion of cycle 23, RM for cycle 24 is predicted to be larger than average, being about 168+/-60 (the 90% prediction interval), whereas based on the expected aam for cycle 24 (greater than or equal to 14.6), RM for cycle 24 should measure greater than or equal to 118+/-30, yielding an overlap of about 128+/-20.

  9. Search for seasonal rhythmicity of pineal melatonin production in rats under constant laboratory conditions: spectral chronobiological analysis, and relation to solar and geomagnetic variables.

    PubMed

    Bartsch, Hella; Mecke, Dieter; Probst, Hansgeorg; Küpper, Heinz; Seebald, Eckard; Salewski, Lothar; Stehle, Thilo; Bartsch, Christian

    2012-10-01

    Earlier we reported that in a number of experiments pineal melatonin production in rats under constant laboratory conditions displayed seasonal rhythms but subsequently were not always able to confirm this. Since there was no indication under which conditions such rhythms may be present, we performed four consecutive identical experiments with untreated female Sprague-Dawley rats within the same animal room during 1997-2006. Nocturnal urine samples (19-23, 23-3, 3-7 h) were collected at monthly intervals over 494-658 d with 12 animals each in experiments I and II (1997-1999, 1999-2000), 30 animals in experiment III (2002-2004), and 15 in experiment IV (2005-2006). 6-Sulfatoxymelatonin (aMT6s) was measured by ELISA. The excreted aMT6s at each time interval as well as total nocturnal aMT6s-excretion (19-7 h) was submitted to standard statistical analyses as well as to a spectral chronobiological analysis to determine the period lengths of the components involved which was followed by processing with the single cosinor method. Seasonal rhythm components (circannual period length: 360 ± 60 d) were detected in experiment III (2002-2004) for the overall nocturnal excretion as well as for two sub-intervals (23-3 and 3-7 h) and in one night interval of experiment II (23-3 h). Multiple components with mostly short period lengths of around 100 d and some long ones of 500-650 d were found in the other experiments. Systematic MESOR and amplitude variations were observed during the experiments, being highest in experiment II (19-7 h, also 23-3 h and 3-7 h) and lowest in experiments I and IV. These results illustrate that seasonal melatonin rhythms are not a general phenomenon in female laboratory rats indicating an involvement of unknown environmental cues. As an extension of our earlier hypothesis regarding a seasonal Zeitgeber function of the horizontal intensity H of the geomagnetic field showing circannual variations, we assume further modulation by the 11-yrs' sunspot

  10. A comparison of FUV dayglows measured by STSAT-1/FIMS with the AURIC model in a geomagnetic quiet condition

    NASA Astrophysics Data System (ADS)

    Kam, Hosik; Kim, Yong Ha; Hong, Jun-Seok; Lee, Joon-Chan; Choi, Yeon-Ju; Min, Kyung Wook

    2014-09-01

    The Korea scientific microsatellite, STSAT-1 (Science and Technology Satellite-1), was launched in 2003 and observed far ultraviolet (FUV) airglow from the upper atmosphere with a Far-ultraviolet IMaging Spectrograph (FIMS) at an altitude of 690 km. The FIMS consists of a dual-band imaging spectrograph of 900-1150 Å (S-band) and 1340-1715 Å (L-band). Limb scanning observations were performed only at the S-band, resulting in intensity profiles of OI 989 Å, OI 1026 Å, NII 1085 Å and NI 1134 Å emission lines near the horizon. We compare these emission intensities with those computed by using a theoretical model, the AURIC (Atmospheric Ultraviolet Radiance Integrated Code). The intensities of the OI 1026 Å, NII 1085 Å and NI 1134 Å emissions measured by using the FIMS are overall consistent with the values computed by using AURIC under the thermospheric and solar activity conditions on August 6, 1984, which is close to the FIMS's observation condition. We find that the FIMS dayglow intensity profiles match reasonably well with AURIC intensity profiles for the MSIS90 oxygen atom density profiles within factors of 0.5 and 2. However, the FIMS intensities of the OI 989 Å line are about 2 ˜ 4 times stronger than the AURIC intensities, which is expected because AURIC does not properly simulate resonance scattering of airglow and solar photons at 989 Å by atomic oxygen in the thermosphere. We also find that the maximum tangential altitudes of the oxygen bearing dayglows (OI 989 Å, OI 1026 Å) are higher than those of the nitrogen-bearing dayglows (NII 1085 Å, NI 1134 Å), which is confirmed by using AURIC model calculations. This is expected because the oxygen atoms are distributed at higher altitudes in the thermosphere than the nitrogen molecules. Validations of the qualities of both the FIMS instrument and the AURIC model indicate that AURIC should be updated with improved thermospheric models and with measured solar FUV spectra for better agreement with the

  11. Could both vitamin D and geomagnetic activity impact serum levels of soluble cell adhesion molecules in young men?

    NASA Astrophysics Data System (ADS)

    Bleizgys, Andrius; Šapoka, Virginijus

    2016-07-01

    Vitamin D might have a role in diminishing endothelial dysfunction (ED). The initial aim was to test the hypothesis of reciprocity between levels of 25-hydroxyvitamin D (25(OH)D) and levels of soluble endothelial cell adhesion molecules (CAMs) that could serve as biomarkers of ED. Randomly selected men of age 20-39 were examined at February or March (cold season) and reexamined at August or September (warm season). Some lifestyle and anthropometrical data were recorded. Laboratory measurements, including those for serum levels of soluble CAMs—sICAM-1, sVCAM-1, sE-selectin and sP-selectin—were also performed. As some of the results were rather unexpected, indices of geomagnetic activity (GMA), obtained from the online database, were included in further analysis as a confounder. In 2012-2013, 130 men were examined in cold season, and 125 of them were reexamined in warm season. 25(OH)D levels were found to be significantly negatively associated with sVCAM-1 levels ( β = -0.15, p = 0.043 in warm season; β = -0.19, p = 0.007 for changes). Levels of sVCAM-1 and sICAM-1 from the same seasons were notably different between years and have changed in an opposite manner. Soluble P-selectin levels were higher at warm season in both years. GMA was positively associated with sVCAM-1 ( β = 0.17, p = 0.039 in cold season; β = 0.22, p = 0.002 for changes) and negatively with sICAM-1 ( β = -0.30. p < 0.001 in cold season) levels. Vitamin D might play a role in diminishing sVCAM-1 levels. Levels of sVCAM-1 and sICAM-1 were associated with the GMA; this implies a need for further research.

  12. Motor activity under weightless conditions

    NASA Technical Reports Server (NTRS)

    Kasyan, I. I.; Kopanev, V. I.; Cherepakhin, M. A.; Yuganov, Y. M.

    1975-01-01

    The material presented on the motor activity under weightless conditions (brief and long) leads to the conclusion that it is not significantly disrupted, if those being examined are secured at the workplaces. Some discoordination of movement, moderately expressed disruption of the precision of reproduction of assigned muscular forces, etc., were observed. Motor disorders decrease significantly in proportion to the length of stay under weightless conditions. This apparently takes place, as a consequence of formation of a new functional system, adequate to the conditions of weightlessness. Tests on intact and labyrinthectomized animals have demonstrated that signaling from the inner ear receptors is superfluous in weightlessness, since it promotes the onset of disruptions in the combined work of the position analyzers.

  13. Morphological changes in the retina in Pacific ocean salmon Oncorhynchus masou fry in response to neutralization of the geomagnetic field in conditions of normal illumination.

    PubMed

    Maksimovich, A A; Kondrashev, S L; Gnyubkina, V P

    2008-10-01

    The studies reported here provide the first demonstration that retinal responses in both the fry of the migratory salmon trout Oncorhynchus masou and the dwarf form of this species changed in conditions of experimental neutralization of the geomagnetic field (GMF); migratory salmon trout fry and dwarves showed different changes. The responses of different types of retinal photoreceptor in migratory salmon trout fry to neutralization of the GMF differed: while rods and double cones perceived neutralization of the GMF as the onset of darkness (the scotopic reaction), single (generally blue-sensitive) cones responded to neutralization of the GMF both as presentation of blue light or (very rarely) ultraviolet irradiation. The retina of dwarf male salmon trout responded to neutralization of the GMF with a double response: rods showed a light (photopic) response, while double (red/green-sensitive) cones produced dark (scotopic) responses. Single (blue-sensitive) cones responded to neutralization of the GMF as bright blue light. Thus, the morphological picture of the retina in dwarf male salmon trout in these experimental conditions corresponds to the perception of blue light. The initial conditions were different--normal diffuse daylight with a brightness of about 7.5 Lx. It is likely that neutralization of the magnetic field had no effect on rods, while double, red-green, cones responded as to darkness, i.e., the fish did not perceive red or green light in the visible spectrum, but perceived only blue and, possibly, ultraviolet light by means of central blue-sensitive and accessory cones. Thus, these experiments demonstrated that in conditions of normal daylight illumination, retinal photoreceptors in salmon fry respond to changes in the earth's magnetic field, i.e., objectively function as magnetoreceptors.

  14. On the Relationship Between Solar Wind Speed, Geomagnetic Activity, and the Solar Cycle Using Annual Values

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    The aa index can be decomposed into two separate components: the leading sporadic component due to solar activity as measured by sunspot number and the residual or recurrent component due to interplanetary disturbances, such as coronal holes. For the interval 1964-2006, a highly statistically important correlation (r = 0.749) is found between annual averages of the aa index and the solar wind speed (especially between the residual component of aa and the solar wind speed, r = 0.865). Because cyclic averages of aa (and the residual component) have trended upward during cycles 11-23, cyclic averages of solar wind speed are inferred to have also trended upward.

  15. On the watch for geomagnetic storms

    USGS Publications Warehouse

    Green, Arthur W.; Brown, William M.

    1997-01-01

    Geomagnetic storms, induced by solar activity, pose significant hazards to satellites, electrical power distribution systems, radio communications, navigation, and geophysical surveys. Strong storms can expose astronauts and crews of high-flying aircraft to dangerous levels of radiation. Economic losses from recent geomagnetic storms have run into hundreds of millions of dollars. With the U.S. Geological Survey (USGS) as the lead agency, an international network of geomagnetic observatories monitors the onset of solar-induced storms and gives warnings that help diminish losses to military and commercial operations and facilities.

  16. Klimovskaya: A new geomagnetic observatory

    NASA Astrophysics Data System (ADS)

    Soloviev, A. A.; Sidorov, R. V.; Krasnoperov, R. I.; Grudnev, A. A.; Khokhlov, A. V.

    2016-05-01

    In 2011 Geophysical Center RAS (GC RAS) began to deploy the Klimovskaya geomagnetic observatory in the south of Arkhangelsk region on the territory of the Institute of Physiology of Natural Adaptations, Ural Branch, Russian Academy of Sciences (IPNA UB RAS). The construction works followed the complex of preparatory measures taken in order to confirm that the observatory can be constructed on this territory and to select the optimal configuration of observatory structures. The observatory equipping stages are described in detail, the technological and design solutions are described, and the first results of the registered data quality control are presented. It has been concluded that Klimovskaya observatory can be included in INTERMAGNET network. The observatory can be used to monitor and estimate geomagnetic activity, because it is located at high latitudes and provides data in a timely manner to the scientific community via the web-site of the Russian-Ukrainian Geomagnetic Data Center. The role of ground observatories such as Klimovskaya remains critical for long-term observations of secular variation and for complex monitoring of the geomagnetic field in combination with low-orbiting satellite data.

  17. Pc3 activity at low geomagnetic latitudes - A comparison with solar wind observations

    NASA Technical Reports Server (NTRS)

    Villante, U.; Lepidi, S.; Vellante, M.; Lazarus, A. J.; Lepping, R. P.

    1992-01-01

    On an hourly time-scale the different roles of the solar wind and interplanetary magnetic field (IMF) parameters on ground micropulsation activity can be better investigated than at longer time-scales. A long-term comparison between ground measurements made at L'Aquila and IMP 8 observations confirms the solar wind speed as the key parameter for the onset of pulsations even at low latitudes, although additional control of the energy transfer from the interplanetary medium to the earth's magnetosphere is clearly exerted by the cone angle. Above about 20 mHz the frequency of pulsations is confirmed to be closely related to the IMF magnitude while, in agreement with model predictions, the IMF magnitude is related to the amplitude of the local fundamental resonant mode. We provide an interesting example in which high resolution measurements simultaneously obtained in the foreshock region and on the ground show that external transversal fluctuations do not penetrate deep into the low latitude magnetosphere.

  18. Improved geomagnetic referencing in the Arctic environment

    USGS Publications Warehouse

    Poedjono, B.; Beck, N.; Buchanan, A. C.; Borri, L.; Maus, S.; Finn, Carol; Worthington, Bill; White, Tim

    2016-01-01

    Geomagnetic referencing uses the Earth’s magnetic field to determine accurate wellbore positioning essential for success in today's complex drilling programs, either as an alternative or a complement to north-seeking gyroscopic referencing. However, fluctuations in the geomagnetic field, especially at high latitudes, make the application of geomagnetic referencing in those areas more challenging. Precise crustal mapping and the monitoring of real-time variations by nearby magnetic observatories is crucial to achieving the required geomagnetic referencing accuracy. The Deadhorse Magnetic Observatory (DED), located at Prudhoe Bay, Alaska, has already played a vital role in the success of several commercial ventures in the area, providing essential, accurate, real-time data to the oilfield drilling industry. Geomagnetic referencing is enhanced with real-time data from DED and other observatories, and has been successfully used for accurate wellbore positioning. The availability of real-time geomagnetic measurements leads to significant cost and time savings in wellbore surveying, improving accuracy and alleviating the need for more expensive surveying techniques. The correct implementation of geomagnetic referencing is particularly critical as we approach the increased activity associated with the upcoming maximum of the 11-year solar cycle. The DED observatory further provides an important service to scientific communities engaged in studies of ionospheric, magnetospheric and space weather phenomena.

  19. Sudden death in epileptic rats exposed to nocturnal magnetic fields that simulate the shape and the intensity of sudden changes in geomagnetic activity: an experiment in response to Schnabel, Beblo and May

    NASA Astrophysics Data System (ADS)

    Persinger, M. A.; McKay, B. E.; O'Donovan, C. A.; Koren, S. A.

    2005-03-01

    To test the hypothesis that sudden unexplained death (SUD) in some epileptic patients is related to geomagnetic activity we exposed rats in which limbic epilepsy had been induced to experimentally produced magnetic fields designed to simulate sudden storm commencements (SSCs). Prior studies with rats had shown that sudden death in groups of rats in which epilepsy had been induced months earlier was associated with the occurrence of SSCs and increased geomagnetic activity during the previous night. Schnabel et al. [(2000) Neurology 54:903 908) found no relationship between SUD in human patients and geomagnetic activity. A total of 96 rats were exposed to either 500, 50, 10 40 nT or sham (less than 10 nT) magnetic fields for 6 min every hour between midnight and 0800 hours (local time) for three successive nights. The shape of the complex, amplitude-modulated magnetic fields simulated the shape and structure of an average SSC. The rats were then seized with lithium and pilocarpine and the mortality was monitored. Whereas 10% of the rats that had been exposed to the sham field died within 24 h, 60% of the rats that had been exposed to the experimental magnetic fields simulating natural geomagnetic activity died (P<.001) during this period. These results suggest that correlational analyses between SUD in epileptic patients and increased geomagnetic activity can be simulated experimentally in epileptic rats and that potential mechanisms might be testable directly.

  20. Could both vitamin D and geomagnetic activity impact serum levels of soluble cell adhesion molecules in young men?

    PubMed

    Bleizgys, Andrius; Šapoka, Virginijus

    2016-07-01

    Vitamin D might have a role in diminishing endothelial dysfunction (ED). The initial aim was to test the hypothesis of reciprocity between levels of 25-hydroxyvitamin D (25(OH)D) and levels of soluble endothelial cell adhesion molecules (CAMs) that could serve as biomarkers of ED. Randomly selected men of age 20-39 were examined at February or March (cold season) and reexamined at August or September (warm season). Some lifestyle and anthropometrical data were recorded. Laboratory measurements, including those for serum levels of soluble CAMs-sICAM-1, sVCAM-1, sE-selectin and sP-selectin-were also performed. As some of the results were rather unexpected, indices of geomagnetic activity (GMA), obtained from the online database, were included in further analysis as a confounder. In 2012-2013, 130 men were examined in cold season, and 125 of them were reexamined in warm season. 25(OH)D levels were found to be significantly negatively associated with sVCAM-1 levels (β = -0.15, p = 0.043 in warm season; β = -0.19, p = 0.007 for changes). Levels of sVCAM-1 and sICAM-1 from the same seasons were notably different between years and have changed in an opposite manner. Soluble P-selectin levels were higher at warm season in both years. GMA was positively associated with sVCAM-1 (β = 0.17, p = 0.039 in cold season; β = 0.22, p = 0.002 for changes) and negatively with sICAM-1 (β = -0.30. p < 0.001 in cold season) levels. Vitamin D might play a role in diminishing sVCAM-1 levels. Levels of sVCAM-1 and sICAM-1 were associated with the GMA; this implies a need for further research. PMID:26546313

  1. Development of a numerical scheme to predict geomagnetic storms after intense solar events and geomagnetic activity 27 days in advance. Final report, 6 Aug 86-16 Nov 90

    SciTech Connect

    Akasofu, S.I.; Lee, L.H.

    1991-02-01

    The modern geomagnetic storm prediction scheme should be based on a numerical simulation method, rather than on a statistical result. Furthermore, the scheme should be able to predict the geomagnetic storm indices, such as the Dst and AE indices, as a function of time. By recognizing that geomagnetic storms are powered by the solar wind-magnetosphere generator and that its power is given in terms of the solar wind speed, the interplanetary magnetic field (IMF) magnitude and polar angle, the authors have made a major advance in predicting both flare-induced storms and recurrent storms. Furthermore, it is demonstrated that the prediction scheme can be calibrated using the interplanetary scintillation (IPS) observation, when the solar disturbance advances about half-way to the earth. It is shown, however, that we are still far from a reliable prediction scheme. The prediction of the IMF polar angle requires future advance in understanding characteristics of magnetic clouds.

  2. Extreme Geomagnetic Storms - 1868 - 2010

    NASA Astrophysics Data System (ADS)

    Vennerstrom, S.; Lefevre, L.; Dumbović, M.; Crosby, N.; Malandraki, O.; Patsou, I.; Clette, F.; Veronig, A.; Vršnak, B.; Leer, K.; Moretto, T.

    2016-05-01

    We present the first large statistical study of extreme geomagnetic storms based on historical data from the time period 1868 - 2010. This article is the first of two companion papers. Here we describe how the storms were selected and focus on their near-Earth characteristics. The second article presents our investigation of the corresponding solar events and their characteristics. The storms were selected based on their intensity in the aa index, which constitutes the longest existing continuous series of geomagnetic activity. They are analyzed statistically in the context of more well-known geomagnetic indices, such as the Kp and Dcx/Dst index. This reveals that neither Kp nor Dcx/Dst provide a comprehensive geomagnetic measure of the extreme storms. We rank the storms by including long series of single magnetic observatory data. The top storms on the rank list are the New York Railroad storm occurring in May 1921 and the Quebec storm from March 1989. We identify key characteristics of the storms by combining several different available data sources, lists of storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks, solar wind in-situ measurements, neutron monitor data, and associated identifications of Forbush decreases as well as satellite measurements of energetic proton fluxes in the near-Earth space environment. From this we find, among other results, that the extreme storms are very strongly correlated with the occurrence of interplanetary shocks (91 - 100 %), Forbush decreases (100 %), and energetic solar proton events (70 %). A quantitative comparison of these associations relative to less intense storms is also presented. Most notably, we find that most often the extreme storms are characterized by a complexity that is associated with multiple, often interacting, solar wind disturbances and that they frequently occur when the geomagnetic activity is already elevated. We also investigate the semiannual variation in storm occurrence

  3. On the Response of Polar Cap Dynamics to Its Solar Wind and Magnetotail Drivers at High Levels of Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Gao, Ye

    In this thesis, I investigate how polar cap dynamics, quantified by the northern polar cap (PCN) index, respond to solar wind direct driving and magnetotail energy unloading during intervals of strong solar wind driving. Using 53 one to two-day intervals with high cross polar cap potential subintervals, I find that, among 11 candidate coupling functions including the electric field of Kan and Lee (1979) and the universal coupling function of Newell et al. (2007), the PCN index correlates most closely with the electric field (EK-R) of Kivelson and Ridley (2008), a form in which the electric field imposed on the ionosphere by low-latitude magnetopause reconnection saturates at high levels of geomagnetic activity. It is found that magnetotail activity, as represented by an unloading AL index (ALU), makes a significant contribution to the PCN index. A linear model is constructed to relate the PCN index to its solar wind and magnetotail drivers. Based on this model, it is estimated that the portion of the PCN index directly driven by the solar wind electric field outweighs the contribution arising from energy release in the magnetotail by roughly a factor of 2. The solar wind dynamic pressure (pdyn) does not play a key role in controlling the PCN index. However, under intense solar wind driving, the number density (n) can influence the solar wind-magnetosphere coupling by changing the solar wind Alfvén conductance, which is incorporated in EK-R. The validity of the linear model is verified by comparing its results with those obtained from a more general, non-linear model, termed additive model. It is found that, except in anomalous events during which the auroral oval expanded poleward to the latitude of the PCN index station and the index increased because of proximity to auroral zone currents, the linear model is a good approximation, since more than 70% of the variation in the PCN index is explained by the linear model. Thus, this linear model provides a useful tool

  4. The observation and simulation of ionospheric response to CIR/high-speed streams-induced geomagnetic activity on 4 April 2005

    NASA Astrophysics Data System (ADS)

    Chen, Yanhong; Wang, Wenbin; Qiu, Na; Liu, Siqing; Gong, Jiancun; Huang, Wengeng

    2016-08-01

    The ionospheric response to corotating interaction region (CIR)-induced geomagnetic activity on 4 April 2005 has been studied using in situ electron density measurements, ground GPS-total electron content (TEC) observations, and numerical simulations of the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). The case study resulted that the ionospheric positive response occurred from high to low latitudes. The positive effect at low latitudes could continue for 4 days, whereas at middle to high latitudes the disturbance mainly lasted only for 1 day. The modeled Ne and TEC from TIE-GCM had a good agreement with those from observations. The simulation results showed that penetration electric fields were responsible for the daytime positive response during the initial and main phases of the geomagnetic storm, while neutral winds were responsible for the presunset positive effects. The long-lasting positive storm effect during the storm recovery time at low latitudes was related to the thermospheric composition (O/N2) changes during the storm event.

  5. Temporal variation of the arterial pressure in healthy young people and its relation to geomagnetic activity in Mexico

    NASA Astrophysics Data System (ADS)

    Azcárate, T.; Mendoza, B.; Sánchez de la Peña, S.; Martínez, J. L.

    2012-11-01

    We present a study of the temporal behavior of the systolic (SBP) and diastolic (DBP) blood pressure for a sample of 51 normotensive, healthy volunteers, 18 men and 33 women with an average age of 19 years old in Mexico City, Mexico, during April and May, 2008. We divided the data by sex along the circadian rhythm. Three geomagnetic storms occurred during the studied time-span. The strongest one, a moderate storm, is attributed to a coronal hole border that reached the Earth. The ANOVA test applied to the strongest storm showed that even though we are dealing with a moderate geomagnetic storm, there are statistically significant responses of the blood pressure. The superposed epoch analysis during a three-day window around the strongest storm shows that on average the largest changes occurred for the SBP. Moreover, the SBP largest increases occurred two days before and one day after this storm, and women are the most sensitive group as they present larger SBP and DBP average changes than men. Finally, given the small size of the sample, we cannot generalize our results.

  6. Geomagnetic disturbance effects on power systems

    SciTech Connect

    Albertson, V.D.; Bozoki, B.; Feero, W.E.; Kappenman, J.G.; Larsen, E.V.; Nordell, D.E.; Ponder, J.; Prabhakara, F.S.; Thompson, K.; Walling, R.

    1993-07-01

    In the northern hemisphere, the aurora borealis is visual evidence of simultaneous fluctuations in the earth's magnetic field (geomagnetic field). These geomagnetic disturbances (GMD's), or geomagnetic storms, can affect a number of man-made systems, including electric power systems. The GMD's are caused by the electromagnetic interaction of the solar wind plasma of protons and electrons with the geomagnetic field. These dynamic impulses in the solar wind are due to solar flares, coronal holes, and disappearing filaments, and reach the earth from one to six days after being emitted by a solar event. Instances of geomagnetic storms affecting telegraph systems were noted in England in 1846, and power system disturbances linked to GMD's were first reported in the United States in 1940. This Working Group report is a summary of the state of knowledge and research activity to the present time, and covers the GMD/Geomagnetically-induced currents (GIC) phenomena, transformer effects, the impact on generators, protective relay effects, and communication system effects. It also summarizes modeling and predicting GIC, measuring and monitoring GIC, mitigation methods, system operating guidelines during GMD's, and alerting and forecasting procedures and needs for the power industry.

  7. The relationship between the human state and external perturbations of atmospheric, geomagnetic and solar origin

    NASA Astrophysics Data System (ADS)

    Gavryuseva, E.; Kroussanova, N.

    2002-12-01

    The relationship between the state of human body and the external factors such as the different phenomena of solar activity, geomagnetic perturbations and local atmospheric characteristics is studied. The monitoring of blood pressure and electro-conductivity of human body in acupuncture points for a group fo 28 people over the period of 1.5 year has been performed daily from February 2001 to August 2002 in Capodimonte Observatory in Naples, Italy. The modified Voll method of electropuncture diagnostics was used. The strong correlation between the human body state and meteo conditions is found and the probable correlation with geomagnetic perturbations is discussed.

  8. New hemispheric geomagnetic indices α with 15 min time resolution

    NASA Astrophysics Data System (ADS)

    Chambodut, Aude; Marchaudon, Aurélie; Lathuillère, Chantal; Menvielle, Michel; Foucault, Etienne

    2015-11-01

    New subauroral α15 indices are proposed. They are based on a simple reproducible algorithm which relies on an as dense as possible network of magnetic observatories in each hemisphere. At first, the variation with time of local geomagnetic activity is determined at each magnetic station. Gathering all obtained stations' precomputed values, a normalization with corrected geomagnetic latitude is determined. Then, for each 15 min interval, magnetic activity on the horizontal component is averaged out over 15 min and corrected using this normalization, before a spline modeling of the longitudinal variation in each hemisphere is applied. Hemispheric and planetary 15 min indices are then computed by arithmetic means. Preliminary statistical results, from probability distribution function over a solar cycle and superposed epoch analysis during storms conditions, show, by comparison with am geomagnetic index series, that new α15 indices are reliable in describing subauroral magnetic activity. These new indices will suit any future user, allowing either to choose the spatial description (planetary versus hemispheric) and/or to choose the temporal resolution, knowing unambiguously all their strengths and caveats.

  9. Determination of Geomagnetically Quiet Time Disturbances of the Ionosphere over Uganda during the Beginning of Solar Cycle

    NASA Astrophysics Data System (ADS)

    Habyarimana, Valence

    2016-07-01

    The ionosphere is prone to significant disturbances during geomagnetically active and quiet conditions. This study focused on the occurrence of ionospheric disturbances during geomagnetically quiet conditions. Ionospheric data comprised of Global Positioning System (GPS)-derived Total Electron Content (TEC), obtained over Mt. Baker, Entebbe, and Mbarara International Global Navigation Satellite System (GNSS) Service (IGS) stations. The Disturbance storm time (Dst) index was obtained from Kyoto University website. The number of geomagnetically quiet days in the period under study were first identified. Their monthly percentages were compared for the two years. The monthly percentage of geomagnetically quiet days for all the months in 2009 numerically exceeded those in 2008. December had the highest percentage of geomagnetically quiet days for both years (94 % in 2008 and 100 % in 2009). Geomagnetically quiet days did not show seasonal dependence. The variation in percentage of geomagnetically quiet days during solstice months (May, June, July, November, December, and January) and equinoctial months (February, March, April, August, September, and October) was not uniform. Geomagnetically quiet time disturbances were found to be more significant from 09:00 UT to 13:00 UT. However, there were some other disturbances of small scale amplitude that occurred between 14:00 UT and 22:00 UT. Further analysis was done to identify the satellites that observed the irregularities that were responsible for TEC perturbations. Satellites are identified by Pseudo Random Numbers (PRNs). The ray path between individual PRNs and the corresponding receivers were analysed. Satellites with PRNs: 3, 7, 8, 19 and 21 registered most of the perturbations. It was found that Q disturbances led to fluctuations in density gradients. Significant TEC perturbations were observed on satellite with PRN 21 with receivers at Entebbe and Mbarara on June 28, 2009 between 18:00 UT and 21:00 UT.

  10. The causes of recurrent geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Lepping, R. P.

    1976-01-01

    The causes of recurrent geomagnetic activity were studied by analyzing interplanetary magnetic field and plasma data from earth-orbiting spacecraft in the interval from November 1973 to February 1974. This interval included the start of two long sequences of geomagnetic activity and two corresponding corotating interplanetary streams. In general, the geomagnetic activity was related to an electric field which was due to two factors: (1) the ordered, mesoscale pattern of the stream itself, and (2) random, smaller-scale fluctuations in the southward component of the interplanetary magnetic field Bz. The geomagnetic activity in each recurrent sequence consisted of two successive stages. The first stage was usually the most intense, and it occurred during the passage of the interaction region at the front of a stream. These large amplitudes of Bz were primarily produced in the interplanetary medium by compression of ambient fluctuations as the stream steepened in transit to 1 A.U. The second stage of geomagnetic activity immediately following the first was associated with the highest speeds in the stream.

  11. Science outreach and capacity building in geomagnetism and space sciences—An Indian Institute of Geomagnetism endeavor

    NASA Astrophysics Data System (ADS)

    Gawali, Praveen; Bhaskar, Ankush; Dhar, Ajay; Ramesh, Durbha Sai

    2016-05-01

    We present an overview of science outreach and capacity building activities at the Indian Institute of Geomagnetism (IIG) against the backdrop of a long history of geomagnetic studies. We also present the future plans of the institute for strengthening these activities.

  12. Correlations of life-span variation parameters in 128 successive generations of Drosophila melanogaster with changes in atmospheric pressure and geomagnetic activity.

    PubMed

    Izmaylov, D M; Obukhova, L K; Konradov, A A

    2005-05-01

    Correlations between the parameters of life-span (LS) distribution of Drosophila melanogaster, including mean LS (MLS) and the time of 10 and 90% population mortality, and some geophysical parameters that are usually beyond the control of researchers dealing with laboratory cultures, including atmospheric pressure, solar activity indices (Wolf's sunspot numbers and 2,800-MHz radio flux), and geomagnetic activity (planetary index, K(p)), were studied. Geophysical data were obtained from free-access official web sites of the National Oceanic & Atmospheric Administration of the US Department of Commerce and the Institute of Terrestrial Magnetism and Radiowave Propagation of the Russian Academy of Sciences. The geophysical parameters were calculated only for the period corresponding to 10 days of preimaginal development of the flies from egg to imago. Canonical correlation analysis, calculation of the non-parametric Spearman rank-order correlation coefficients, and graphical data analysis were used. Highly significant correlations between parameters of LS distribution in males and females and environmental factors, such as the atmospheric pressure on the 4th and 5th day of development and geomagnetic activity indices (K(p)) on the 6th and 10th day of development were found, with correlation coefficients varying from 0.31 to 0.37 (P<0.02). Assuming a causal relationship between geophysical factors and LS, it may be hypothesized that energetically weak environmental factors determine the formation of LS oscillatory dynamics in laboratory populations. The possible mechanisms underlying the contribution of these environmental factors to the LS variation in successive generations are discussed.

  13. Hemodynamic response characteristics of healthy people to changes in meteorological and geomagnetic factors in the north

    NASA Astrophysics Data System (ADS)

    Zenchenko, T. A.; Varlamova, N. G.

    2015-12-01

    This paper analyzes the influence of variations in meteorological and geomagnetic factors on hemodynamic parameters (HP) in 27 healthy volunteers who are residents of Syktyvkar (daily monitoring of blood pressure (BP) and heart rate (HR) and stroke and cardiac output for the period from December 1, 2003, to December 31, 2004). It is shown that temperature variations and geomagnetic activity level (GMA) make the greatest impact on HP changes (85 and 48% cases, respectively). The BP level increases with decreasing temperature and with increasing levels of GMA. The sensitivity of systolic and diastolic blood pressure to the meteorological and geomagnetic factors is approximately twice as high as the sensitivity of other HP to them. The individual values of seasonal changes in BP parameters are 4-9 mmHg for systolic blood pressure and 3-6 mmHg for diastolic blood pressure. The estimates of the characteristics of meteorological and geomagnetic sensitivity in residents of northern latitudes are in good agreement with the results obtained by us earlier for other climatic zones and geomagnetic conditions, logically complementing and enhancing the common space-time picture of the reactions of the human body to external impacts.

  14. Geomagnetic storms, super-storms, and their impacts on GPS-based navigation systems

    NASA Astrophysics Data System (ADS)

    Astafyeva, E.; Yasyukevich, Yu.; Maksikov, A.; Zhivetiev, I.

    2014-07-01

    Using data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super-storms and two intense storms. We show that during super-storms the density of GPS Losses-of-Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM-H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

  15. Lidar and CTIPe model studies of the fast amplitude growth with altitude of the diurnal temperature "tides" in the Antarctic winter lower thermosphere and dependence on geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Fong, Weichun; Chu, Xinzhao; Lu, Xian; Chen, Cao; Fuller-Rowell, Timothy J.; Codrescu, Mihail; Richmond, Arthur D.

    2015-02-01

    Four years of lidar observations at McMurdo reveal that the fast amplitude growth with altitude of diurnal temperature tides from 100 to 110 km during Antarctic winters, exceeding that of the freely propagating tides from the lower atmosphere, increases in strength with the Kp magnetic activity index. Simulations with the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) model reproduce the lidar observations and exhibit concentric ring structures of diurnal amplitudes encircling the south geomagnetic pole and overlapping the auroral zone. These findings point to a magnetospheric source origin. Mechanistic studies using CTIPe show that the adiabatic cooling/heating associated with Hall ion drag is the dominant source of this feature, while Joule heating is a minor contributor due to the counteraction by Joule-heating-induced adiabatic cooling. The sum of total dynamical effects and Joule heating explains ~80% of the diurnal amplitudes. Auroral particle heating, lower atmosphere tides, and direct solar heating have minor contributions.

  16. A new regard about Surlari National Geomagnetic Observatory

    NASA Astrophysics Data System (ADS)

    Asimopolos, Laurentiu; Asimopolos, Natalia-Silvia; Pestina, Agata-Monica

    2010-05-01

    Geomagnetic field study in Romanian stations has started with irregular measurements in late XIXth century. In 1943, the foundation of Surlari National Geomagnetic Observatory (SNGO) marks the beginning of a new era in the systematic study of geomagnetic field by a continuous registration of its variations and by carrying out standard absolute measurements in a fundamental station. The location of the observatory meets the highest exigencies, being situated in physical-geological conditions of a uniform local field, at a reasonably long distance from human activities. Its laboratories observe strict conditions of non-magnetism, ensuring the possibility of absolute standard measurements (national magnetic standards) for all the units in the country, civil or military, which are endowed with equipment based on geomagnetic metrology. These basic conditions have allowed the observatory to become by developing its initial preoccupations a centre of complex geomagnetic research, constantly involved in national and international issues, promoting new themes in our country and bringing significant contributions. During the last two decades, infrastructure and equipment used in monitoring geomagnetic field at European and planetary level have experienced a remarkable development. New registering techniques have allowed a complete to automate of data acquisition, and sampling step and their precision increased by two classes of size. Systems of transmitting these data in real time to world collecting centres have resulted in the possibility of approaching globalize studies, suitable for following some phenomena at planetary scale. At the same time, a significant development in the procedures of processing primary data has been registered, based on standardized programmes. The new stage of this fundamental research, largely applicable in various fields, is also marked by the simultaneous observation of space-time distribution of terrestrial electromagnetic field by means of

  17. The influence of meteorological and geomagnetic factors on acute myocardial infarction and brain stroke in Moscow, Russia.

    PubMed

    Shaposhnikov, Dmitry; Revich, Boris; Gurfinkel, Yuri; Naumova, Elena

    2014-07-01

    Evidence of the impact of air temperature and pressure on cardiovascular morbidity is still quite limited and controversial, and even less is known about the potential influence of geomagnetic activity. The objective of this study was to assess impacts of air temperature, barometric pressure and geomagnetic activity on hospitalizations with myocardial infarctions and brain strokes. We studied 2,833 myocardial infarctions and 1,096 brain strokes registered in two Moscow hospitals between 1992 and 2005. Daily event rates were linked with meteorological and geomagnetic conditions, using generalized linear model with controls for day of the week, seasonal and long-term trends. The number of myocardial infarctions decreased with temperature, displayed a U-shaped relationship with pressure and variations in pressure, and increased with geomagnetic activity. The number of strokes increased with temperature, daily temperature range and geomagnetic activity. Detrimental effects on strokes of low pressure and falling pressure were observed. Relative risks of infarctions and strokes during geomagnetic storms were 1.29 (95% CI 1.19-1.40) and 1.25 (1.10-1.42), respectively. The number of strokes doubled during cold spells. The influence of barometric pressure on hospitalizations was relatively greater than the influence of geomagnetic activity, and the influence of temperature was greater than the influence of pressure. Brain strokes were more sensitive to inclement weather than myocardial infarctions. This paper provides quantitative estimates of the expected increases in hospital admissions on the worst days and can help to develop preventive health plans for cardiovascular diseases.

  18. The influence of meteorological and geomagnetic factors on acute myocardial infarction and brain stroke in Moscow, Russia

    NASA Astrophysics Data System (ADS)

    Shaposhnikov, Dmitry; Revich, Boris; Gurfinkel, Yuri; Naumova, Elena

    2014-07-01

    Evidence of the impact of air temperature and pressure on cardiovascular morbidity is still quite limited and controversial, and even less is known about the potential influence of geomagnetic activity. The objective of this study was to assess impacts of air temperature, barometric pressure and geomagnetic activity on hospitalizations with myocardial infarctions and brain strokes. We studied 2,833 myocardial infarctions and 1,096 brain strokes registered in two Moscow hospitals between 1992 and 2005. Daily event rates were linked with meteorological and geomagnetic conditions, using generalized linear model with controls for day of the week, seasonal and long-term trends. The number of myocardial infarctions decreased with temperature, displayed a U-shaped relationship with pressure and variations in pressure, and increased with geomagnetic activity. The number of strokes increased with temperature, daily temperature range and geomagnetic activity. Detrimental effects on strokes of low pressure and falling pressure were observed. Relative risks of infarctions and strokes during geomagnetic storms were 1.29 (95 % CI 1.19-1.40) and 1.25 (1.10-1.42), respectively. The number of strokes doubled during cold spells. The influence of barometric pressure on hospitalizations was relatively greater than the influence of geomagnetic activity, and the influence of temperature was greater than the influence of pressure. Brain strokes were more sensitive to inclement weather than myocardial infarctions. This paper provides quantitative estimates of the expected increases in hospital admissions on the worst days and can help to develop preventive health plans for cardiovascular diseases.

  19. The influence of meteorological and geomagnetic factors on acute myocardial infarction and brain stroke in Moscow, Russia.

    PubMed

    Shaposhnikov, Dmitry; Revich, Boris; Gurfinkel, Yuri; Naumova, Elena

    2014-07-01

    Evidence of the impact of air temperature and pressure on cardiovascular morbidity is still quite limited and controversial, and even less is known about the potential influence of geomagnetic activity. The objective of this study was to assess impacts of air temperature, barometric pressure and geomagnetic activity on hospitalizations with myocardial infarctions and brain strokes. We studied 2,833 myocardial infarctions and 1,096 brain strokes registered in two Moscow hospitals between 1992 and 2005. Daily event rates were linked with meteorological and geomagnetic conditions, using generalized linear model with controls for day of the week, seasonal and long-term trends. The number of myocardial infarctions decreased with temperature, displayed a U-shaped relationship with pressure and variations in pressure, and increased with geomagnetic activity. The number of strokes increased with temperature, daily temperature range and geomagnetic activity. Detrimental effects on strokes of low pressure and falling pressure were observed. Relative risks of infarctions and strokes during geomagnetic storms were 1.29 (95% CI 1.19-1.40) and 1.25 (1.10-1.42), respectively. The number of strokes doubled during cold spells. The influence of barometric pressure on hospitalizations was relatively greater than the influence of geomagnetic activity, and the influence of temperature was greater than the influence of pressure. Brain strokes were more sensitive to inclement weather than myocardial infarctions. This paper provides quantitative estimates of the expected increases in hospital admissions on the worst days and can help to develop preventive health plans for cardiovascular diseases. PMID:23700198

  20. Geomagnetic Observatory Data for Real-Time Applications

    NASA Astrophysics Data System (ADS)

    Love, J. J.; Finn, C. A.; Rigler, E. J.; Kelbert, A.; Bedrosian, P.

    2015-12-01

    The global network of magnetic observatories represents a unique collective asset for the scientific community. Historically, magnetic observatories have supported global magnetic-field mapping projects and fundamental research of the Earth's interior and surrounding space environment. More recently, real-time data streams from magnetic observatories have become an important contributor to multi-sensor, operational monitoring of evolving space weather conditions, especially during magnetic storms. In this context, the U.S. Geological Survey (1) provides real-time observatory data to allied space weather monitoring projects, including those of NOAA, the U.S. Air Force, NASA, several international agencies, and private industry, (2) collaborates with Schlumberger to provide real-time geomagnetic data needed for directional drilling for oil and gas in Alaska, (3) develops products for real-time evaluation of hazards for the electric-power grid industry that are associated with the storm-time induction of geoelectric fields in the Earth's conducting lithosphere. In order to implement strategic priorities established by the USGS Natural Hazards Mission Area and the National Science and Technology Council, and with a focus on developing new real-time products, the USGS is (1) leveraging data management protocols already developed by the USGS Earthquake Program, (2) developing algorithms for mapping geomagnetic activity, a collaboration with NASA and NOAA, (3) supporting magnetotelluric surveys and developing Earth conductivity models, a collaboration with Oregon State University and the NSF's EarthScope Program, (4) studying the use of geomagnetic activity maps and Earth conductivity models for real-time estimation of geoelectric fields, (5) initiating geoelectric monitoring at several observatories, (6) validating real-time estimation algorithms against historical geomagnetic and geoelectric data. The success of these long-term projects is subject to funding constraints

  1. The calculation of corrected geomagnetic coordinates in the high latitude region

    NASA Astrophysics Data System (ADS)

    Alperovich, Leonid; Levitin, Anatoly; Gromova, Lyudmila; Dremukhina, Lyudmila

    Because the real geomagnetic field in Space, especially during geomagnetic perturbations has very complex spatial distribution, we had to use adjusted geomagnetic coordinates. The calculation of these coordinates is connected with the correct calculation of field lines inclusive the internal IGRF (International Geomagnetic Reference Field) and external geomagnetic field. Tables of such coordinates are somewhat incorrect as they do not account for the coordinates' dependency on geomagnetic activity dynamics. We demonstrate how the coordinates vary with geomagnetic activity in high latitude regions. The calculations revealed that during magnetic storms in a major part of the near pole area the field lines are disclosed and for points of this area on the earth's surface the corrected geomagnetic coordinates cannot be calculated.

  2. Geomagnetic Workshop, Canberra

    NASA Astrophysics Data System (ADS)

    Barton, C. E.; Lilley, F. E. M.; Milligan, P. R.

    On May 14-15, 1985, 63 discerning geomagnetists flocked to Canberra to attend the Geomagnetic Workshop coorganized by the Australian Bureau of Mineral Resources (BMR) and the Research School of Earth Sciences, Australian National University (ANU). With an aurorally glowing cast that included an International Association of Geomagnetism and Aeronomy (IAGA) president, former president, and division chairman, the Oriental Magneto-Banquet (which was the center of the meeting), was assured of success. As a cunning ploy to mask the true nature of this gastronomic extravagance from the probings of income tax departments, a presentation of scientific papers on Australian geomagnetism in its global setting was arranged.The Australian region, including New Zealand, Papua New Guinea, Indonesia, and a large sector of the Antarctic, covers one eighth of the Earth's surface and historically has played an important role in the study of geomagnetism. The region contains both the south magnetic and geomagnetic poles, and two Australian Antarctic stations (Casey and Davis) are situated in the region of the south polar cusp (see Figure 1).

  3. Search for correlation between geomagnetic disturbances and mortality

    NASA Technical Reports Server (NTRS)

    Lipa, B. J.; Barnes, C. W.; Sturrock, P. A.; Feinleib, M.; Rogot, E.

    1975-01-01

    Statistical evaluation of death rates in the U.S.A. from heart diseases or stroke did not show any correlation with measured geomagnetic pulsations and thus do not support a claimed relationship between geomagnetic activity and mortality rates to low frequency fluctuations of the earth's magnetic field.

  4. Do Coronal Holes Cause 27 Day Recurring Geomagnetic Storms?

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.; Gonzalez, Alicia L. C.; Tang, Frances; Park, Dan; Okada, Masaki; Arballo, John

    1994-01-01

    We examine 3 years of interplanetary data and geomagnetic activity indices (1973-1975) to determine the causes of geomagnetic storms and substorms during the descending phase of the solar cycle. In this paper, we specifically studied the year 1974 where two long lasting coronating streams existed.

  5. Snowstorm at the geomagnetic observatory

    NASA Astrophysics Data System (ADS)

    Čop, R.

    2015-08-01

    The Sinji Vrh Geomagnetic Observatory (hereinafter the Observatory) is situated on Gora above Ajdovščina, a highland karst plateau, in the southwestern part of Slovenia. The Observatory operates in exceptional geological and meteorological conditions due to its location. The very first measurements at the time of initial tests showed that weather fronts induce changes in the local magnetic field. The first measurements intended to determine the value of this influence were carried out at the end of summer 2011. In 2013 the first such measurements were carried out in January. This article presents the results of these measurements, showing how the snowstorm induced changes in Earth's magnetic field.

  6. Investigation of the Effects of Solar and Geomagnetic Changes on the Total Electron Content: Mid-Latitude Region

    NASA Astrophysics Data System (ADS)

    Ulukavak, Mustafa; Yalcinkaya, Mualla

    2016-04-01

    The Global Positioning System (GPS) is used as an important tool for ionosphere monitoring and obtaining the Total Electron Content (TEC). GPS satellites, positioned in the Earth's orbit, are used as sensors to investigate the space weather conditions. In this study, solar and geomagnetic activity variations were investigated between the dates 1 March-30 June 2015 for the mid-latitude region. GPS-TEC variations were calculated for each selected International GNSS Service (IGS) station in Europe. GNSS data was obtained from Crustal Dynamics Data and Information System (CDDIS) archive. Solar and geomagnetic activity indices (Kp, F10.7 ve Dst) were obtained from the Oceanic and Atmospheric Administration (NOAA), the Canadian Space Weather Forecast Centre (CSWFC) and Data Analysis Center for geomagnetism and Space Magnetism Graduate School of Science, Kyoto University (WDC) archives. GPS-TEC variations were determined for the quiet periods of the solar and geomagnetic activities. GPS-TEC changes were then compared with respect to the quiet periods of the solar and geomagnetic activities. Global Ionosphere Maps (GIM) IONEX files, obtained from the IGS analysis center, was used to check the robustness of the GPS-TEC variations. The investigations revealed that it is possible to use the GPS-TEC data for monitoring the ionospheric disturbances.

  7. Total electron content behavior over Japan during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Kutiev, Ivan; Watanabe, Shigeto; Otsuka, Yoichi; Saito, Akinori

    2005-01-01

    The total electron content (TEC) obtained from GPS signals is used to study ionospheric dynamics over Japan during geomagnetically disturbed conditions. The numerous TEC measurements are averaged in cells with a size 1.5° × 1.5° geographic scale and formatted as time series within the years 2000-2002. To extract the storm time changes of TEC, the diurnal and 27-day periodicities are subsequently removed. Diurnal variations are removed by replacing absolute TEC values in each cell with their relative deviations (RTEC) from medians. The hourly RTEC values from all cells within the central 4°-wide band over Japan area are then approximated by a plane surface. This surface is represented by two parameters: its value at the center (rt) and the slope (b) along the main axis, taken as constants of the linear regression. The 27-day periodicity was approximated by Fourier waves with main period of 640 hours and two harmonics separately for rt and b and subtracted from them. The analysis of rt and b behavior during a number of geomagnetic storms allowed us to reveal several repeatable features of average TEC behavior. It was found that TEC behavior during the storms is similar to that of foF2 at the F region and was local time-dependent. A marked poleward expansion of the equatorial ionosphere (crest region) at the end of recovery phase is persistently observed feature, produced probably by intensified eastward zonal winds. Such an expansion of equatorial ionosphere is observed also during isolated substorms, outside main geomagnetic storms. An oscillation-like change of positive and negative disturbances with period of 24 hours is observed during a 4-day period, following a moderate storm. In the absence of geomagnetic activity driver that effect is probably caused by the alternative expansion and contraction of equatorial ionosphere.

  8. Principles of major geomagnetic storms forecasting

    NASA Astrophysics Data System (ADS)

    Zagnetko, Alexander; Applbaum, David; Dorman, Lev; Pustil'Nik, Lev; Sternlieb, Abraham; Zukerman, Igor

    According to NOAA Space Weather Scales, geomagnetic storms of scales G5 (3-hour index of geomagnetic activity Kp=9), G4 (Kp=8) and G3 (Kp=7) are dangerous for people technology and health (influence on power systems, on spacecraft operations, on HF radio-communications and others). To prevent these serious damages will be very important to forecast dangerous geomagnetic storms. In many papers it was shown that in principle for this forecasting can be used data on CR intensity and CR anisotropy changing before SC of major geomagnetic storms accompanied by sufficient Forbush-decreases (e.g., Dorman et al., 1995, 1999). In this paper we consider all types of observed precursor effects in CR what can be used for forecasting of great geomagnetic storms and possible mechanisms of these precursor effects origin. REFERENCES: Dorman L.I., et al. "Cosmic-ray forecasting features for big Forbush-decreases". Nuclear Physics B, 49A, 136-144 (1995). L.I.Dorman, et al, "Cosmic ray Forbush-decrease as indicators of space dangerous phenomenon and possible use of cosmic ray data for their pre-diction", Proc. of 26-th Intern. Cosmic Ray Conference, Salt Lake City, 6, 476-479 (1999).

  9. Search for correlation between geomagnetic disturbances and mortality

    NASA Technical Reports Server (NTRS)

    Lipa, B. J.; Sturrock, P. A.; Rogot, F.

    1976-01-01

    A search is conducted for a possible correlation between solar activity and myocardial infarction and stroke in the United States. A statistical analysis is performed using data on geomagnetic activity and the daily U.S. mortality due to coronary heart disease and stroke for the years 1962 through 1966. None of the results are found to yield any evidence of a correlation. It is concluded that correlations claimed by Soviet workers between geomagnetic activity and the incidence of various human diseases are probably not statistically significant or probably are not due to a causal relation between geomagnetic activity and disease.

  10. An introduction to quiet daily geomagnetic fields

    USGS Publications Warehouse

    Campbell, W.H.

    1989-01-01

    On days that are quiet with respect to solar-terrestrial activity phenomena, the geomagnetic field has variations, tens of gamma in size, with major spectral components at about 24, 12, 8, and 6 hr in period. These quiet daily field variations are primarily due to the dynamo currents flowing in the E region of the earth's ionosphere, are driven by the global thermotidal wind systems, and are dependent upon the local tensor conductivity and main geomagnetic field vector. The highlights of the behavior and interpretation of these quiet field changes, from their discovery in 1634 until the present, are discussed as an introduction to the special journal issue on Quiet Daily Geomagnetic Fields. ?? 1989 Birkha??user Verlag.

  11. Assessment of extreme values in geomagnetic and geoelectric field variations for Canada

    NASA Astrophysics Data System (ADS)

    Nikitina, L.; Trichtchenko, L.; Boteler, D. H.

    2016-07-01

    Disturbances of the geomagnetic field produced by space weather events can have an impact on power systems and other critical infrastructure. To mitigate these risks it is important to determine the extreme values of geomagnetic activity that can occur. More than 40 years of 1 min magnetic data recorded at 13 Canadian geomagnetic observatories have been analyzed to evaluate extreme levels in geomagnetic and geoelectric activities in different locations of Canada. The hourly ranges of geomagnetic field variations and hourly maximum in rate of change of the magnetic variations have been used as measures of geomagnetic activity. Geoelectric activity is estimated by the hourly peak amplitude of the geoelectric fields calculated with the use of Earth resistivity models specified for different locations in Canada. A generalized extreme value distribution was applied to geomagnetic and geoelectric indices to evaluate extreme geomagnetic and geoelectric disturbances, which could happen once per 50 and once per 100 years with 99% confidence interval. Influence of geomagnetic latitude and Earth resistivity models on the results for the extreme geomagnetic and geoelectric activity is discussed. The extreme values provide criteria for assessing the vulnerability of power systems and other technology to geomagnetic activity for design or mitigation purposes.

  12. Introduction to Geomagnetic Fields

    NASA Astrophysics Data System (ADS)

    Hinze, William J.

    Coincidentally, as I sat down in late October 2003 to read and review the second edition of Wallace H. Campbell's text, Introduction to Geomagnetic Fields, we received warnings from the news media of a massive solar flare and its possible effect on power supply systems and satellite communications. News programs briefly explained the source of Sun-Earth interactions. If you are interested in learning more about the physics of the connection between sun spots and power supply systems and their impact on orbiting satellites, I urge you to become acquainted with Campbell's book. It presents an interesting and informative explanation of the geomagnetic field and its applications to a wide variety of topics, including oil exploration, climate change, and fraudulent claims of the utility of magnetic fields for alleviating human pain. Geomagnetism, the study of the nature and processes of the Earth's magnetic fields and its application to the investigation of the Earth, its processes, and history, is a mature science with a well-developed theoretical foundation and a vast array of observations. It is discussed in varied detail in Earth physics books and most entry-level geoscience texts. The latter treatments largely are driven by the need to discuss paleomagnetism as an essential tool in studying plate tectonics. A more thorough explanation of geomagnetism is needed by many interested scientists in related fields and by laypersons. This is the objective of Campbell's book. It is particularly germane in view of a broad range of geomagnetic topics that are at the forefront of today's science, including environmental magnetism, so-called ``jerks'' observed in the Earth's magnetic field, the perplexing magnetic field of Mars, improved satellite magnetic field observations, and the increasing availability of high-quality continental magnetic anomaly maps, to name only a few.

  13. Variation of Plasmaspheric (90-4000 km) Field-aligned Electron Density and Ion Composition as a Function of Geomagnetic Storm Activity

    NASA Astrophysics Data System (ADS)

    Reddy, A.; Sonwalkar, V. S.

    2015-12-01

    Whistler mode (WM) radio sounding from IMAGE has led to the first measurements of plasmaspheric field-aligned electron density and ion composition as a function of geomagnetic storm activity during Aug-Sep 2005, a period that included several successive geomagnetic storms of varying strength. The plasmapause was located at L~2.4 during the onset and main phases of the storms. On the dayside, as a function of storm activity we found in general the following results: (1) The electron density, relative ion concentrations, and O+/H+ transition height had different temporal behavior. (2) Electron density in the first 1-2 days of the storm increased followed by a decrease in the recovery phase. (3) αH+ decreased during the onset, main and early recovery phase, and then it increased; αO+ increased in the early recovery phase, and then it decreased; αHe+ in general increased in the onset or main phase and decreased in the recovery phase. (4) O+/H+ transition height increased by ~200-300 km during the onset, main and early recovery phase. (5) When successive storms occurred in less than a day's span, the latter storms had little or no effect on the electron density and ion composition. On the nightside, WM sounding data was sparse. In the case of one moderate storm, we found that 3 days after the storm, electron density at F2 peak and relative ion concentrations (at all altitudes) were comparable to those before the storm, whereas electron density above O+/H+ transition height decreased. WM sounding results for the dayside and nightside were in agreement with measurements from CHAMP (350 km) and DMSP (850 km). WM sounding measurements coupled with physics-based models (e.g. SAMI2) will allow: (a) investigation of the role of thermospheric winds, dynamo and storm time electric fields in causing the variations in electron and ion densities, and (b) testing of current theories and validating physics-based models of the thermosphere-ionosphere-magnetosphere coupling.

  14. Helio-geomagnetic influence in cardiological cases

    NASA Astrophysics Data System (ADS)

    Katsavrias, Ch.; Preka-Papadema, P.; Moussas, X.; Apostolou, Th.; Theodoropoulou, A.; Papadima, Th.

    2013-01-01

    The effects of the energetic phenomena of the Sun, flares and coronal mass ejections (CMEs) on the Earth's ionosphere-magnetosphere, through the solar wind, are the sources of the geomagnetic disturbances and storms collectively known as Space Weather. The research on the influence of Space Weather on biological and physiological systems is open. In this work we study the Space Weather impact on Acute Coronary Syndromes (ACS) distinguishing between ST-segment elevation acute coronary syndromes (STE-ACS) and non-ST-segment elevation acute coronary syndromes (NSTE-ACS) cases. We compare detailed patient records from the 2nd Cardiologic Department of the General Hospital of Nicaea (Piraeus, Greece) with characteristics of geomagnetic storms (DST), solar wind speed and statistics of flares and CMEs which cover the entire solar cycle 23 (1997-2007). Our results indicate a relationship of ACS to helio-geomagnetic activity as the maximum of the ACS cases follows closely the maximum of the solar cycle. Furthermore, within very active periods, the ratio NSTE-ACS to STE-ACS, which is almost constant during periods of low to medium activity, changes favouring the NSTE-ACS. Most of the ACS cases exhibit a high degree of association with the recovery phase of the geomagnetic storms; a smaller, yet significant, part was found associated with periods of fast solar wind without a storm.

  15. Variations in the thermosphere and ionosphere response to the 17-20 April 2002 geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Fang, Hanxian; Weng, Libin; Sheng, Zheng

    2012-05-01

    The responses of the thermospheric density and ionospheric foF2 to the intense magnetic storms event on 17-20 April were analyzed by using data from CHAMP/STAR and ionosonde stations respectively, and NRLMSISE-00 and IRI-2007 models were used to simulate. The models can capture the tendency of changes, especially under quiet or moderate geomagnetic conditions, but are less accurate under geomagnetic storms. The thermospheric density is sensitive to the EUV emission and geomagnetic activity, and double-peak structure appeared in the dayside. On 19 April dayside, TADs traveled toward the equator with phase speeds of the order of 300-750 m/s, interfered near the equator to produce a total density perturbation of 25%, and then passed through each other and into the opposite hemisphere. For ionospheric foF2, there are non-symmetric hemispheres' features during the intense geomagnetic activities. In details, middle latitudes in the north and high latitudes in both hemispheres are negative ionospheric storms, and the maximum amplitudes of δfoF2 is about 60%, but the amplitudes decrease from the higher to lower latitudes in the Southern Hemisphere. Meanwhile, the equatorial station shows positive phase, and the maximum value is about 100%. Finally, the mechanisms for these features will be discussed in this study.

  16. The effect of solar-geomagnetic activity during hospital admission on coronary events within 1 year in patients with acute coronary syndromes

    NASA Astrophysics Data System (ADS)

    Vencloviene, J.; Babarskiene, R.; Milvidaite, I.; Kubilius, R.; Stasionyte, J.

    2013-12-01

    Some evidence indicates the deterioration of the cardiovascular system during space storms. It is plausible that the space weather conditions during and after hospital admission may affect the risk of coronary events in patients with acute coronary syndromes (ACS). We analyzed the data of 1400 ACS patients who were admitted to the Hospital Lithuanian University of Health Sciences, and who survived for more than 4 days. We evaluated the associations between geomagnetic storms (GS), solar proton events (SPE), and solar flares (SF) that occurred 0-3 days before and after hospital admission and the risk of cardiovascular death (CAD), non-fatal ACS, and coronary artery bypass grafting (CABG) during a period of 1 year; the evaluation was based on the multivariate logistic model, controlling for clinical data. After adjustment for clinical variables, GS occurring in conjunction with SF 1 day before admission increased the risk of CAD by over 2.5 times. GS 2 days after SPE occurred 1 day after admission increased the risk of CAD and CABG by over 2.8 times. The risk of CABG increased by over 2 times in patients admitted during the day of GS and 1 day after SPE. The risk of ACS was by over 1.63 times higher for patients admitted 1 day before or after solar flares.

  17. Foundations of Geomagnetism

    NASA Astrophysics Data System (ADS)

    Jackson, Andy

    The study of the magnetic field of the Earth, or geomagnetism, is one of the oldest lines of scientific enquiry. Indeed, it has often been said that William Gilbert's De Magnete, published in 1600 and predating Isaac Newton's Principia by 87 years, can claim to be the first true scientific textbook; his study was essentially the first of academic rather than practical interest.What then, we may ask, has been accomplished in the nearly 400 intervening years up to the publication of Foundations of Geomagnetism? In short, a wealth of observational evidence, considerable physical understanding, and a great deal of mathematical apparatus have accrued, placing the subject on a much surer footing.The latter two categories are described in considerable detail, and with attendant rigor, in this book. The sphericity of the Earth means that a frequent theme in the book is the solution of the partial differential equations of electrodynamics in a spherical geometry.

  18. On regional geomagnetic charts

    USGS Publications Warehouse

    Alldredge, L.R.

    1987-01-01

    When regional geomagnetic charts for areas roughly the size of the US were compiled by hand, some large local anomalies were displayed in the isomagnetic lines. Since the late 1960s, when the compilation of charts using computers and mathematical models was started, most of the details available in the hand drawn regional charts have been lost. One exception to this is the Canadian magnetic declination chart for 1980. This chart was constructed using a 180 degrees spherical harmonic model. -from Author

  19. Geomagnetism. Volume I

    SciTech Connect

    Jacobs, J.A.

    1987-01-01

    The latest attempt to summarise the wealth of knowledge now available on geomagnetic phenomena has resulted in this multi-volume treatise, with contributions and reviews from many scientists. The first volume in the series contains a thorough review of all existing information on measuring the Earth's magnetic field, both on land and at sea, and includes a comparative analysis of the techniques available for this purpose.

  20. Space radiation enhancement linked to geomagnetic disturbances.

    PubMed

    Tomita, F; Den, M; Doke, T; Hayashi, T; Nagaoka, T; Kato, M

    1997-12-01

    Space radiation dosimetry measurements have been made on board the Space Shuttle. A newly developed active detector called "Real-time Radiation Monitoring Device (RRMD)" was used (Doke et al., 1995; Hayashi et al., 1995). The RRMD results indicate that low Linear Energy Transfer (LET) particles steadily penetrate around the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent and some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions (Doke et al., 1996). We also have been analyzing the space weather during the experiment, and found that the anomalous high-energy particle enhancement was linked to geomagnetic disturbance due to the high speed solar wind from a coronal hole. Additional analysis and other experiments are necessary for clarification of these phenomena. If a penetration of high-energy particles into the low altitude occurs by common geomagnetic disturbances, the prediction of geomagnetic activity becomes more important in the next Space Station's era. PMID:11541771

  1. Space radiation enhancement linked to geomagnetic disturbances.

    PubMed

    Tomita, F; Den, M; Doke, T; Hayashi, T; Nagaoka, T; Kato, M

    1998-01-01

    Space radiation dosimetry measurements have been made on board the Space Shuttle. A newly developed active detector called "Real-time Radiation Monitoring Device (RRMD)" was used (Doke et al., 1995; Hayashi et al., 1995). The RRMD results indicate that low Linear Energy Transfer (LET) particles steadily penetrate around the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent and some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions (Doke et al., 1996). We also have been analyzing the space weather during the experiment, and found that the anomalous high-energy particle enhancement was linked to geomagnetic disturbance due to the high speed solar wind from a coronal hole. Additional analysis and other experiments are necessary for clarification of these phenomena. If a penetration of high-energy particles into the low altitude occurs by common geomagnetic disturbances, the prediction of geomagnetic activity becomes more important in the next Space Station's era. PMID:11541929

  2. On extreme geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Cid, Consuelo; Palacios, Judith; Saiz, Elena; Guerrero, Antonio; Cerrato, Yolanda

    2014-10-01

    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.

  3. Spiking the Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Constable, C.; Davies, C. J.

    2015-12-01

    Geomagnetic field intensities corresponding to virtual axial dipole moments of up to 200 ZAm2, more than twice the modern value, have been inferred from archeomagnetic measurements on artifacts dated at or shortly after 1000 BC. Anomalously high values occur in the Levant and Georgia, but not in Bulgaria. The origin of this spike is believed to lie in Earth's core: however, its spatio-temporal characteristics and the geomagnetic processes responsible for such a feature remain a mystery. We show that a localized spike in the radial magnetic field at the core-mantle boundary (CMB) must necessarily contribute to the largest scale changes in Earth's surface field, namely the dipole. Even the limiting spike of a delta function at the CMB produces a minimum surface cap size of 60 degrees for a factor of two increase in paleointensity. Combined evidence from modern satellite and millennial scale field modeling suggests that the Levantine Spike is intimately associated with a strong increase in dipole moment prior to 1000 BC and likely the product of north-westward motion of concentrated near equatorial Asian flux patches like those seen in the modern field. New archeomagnetic studies are needed to confirm this interpretation. Minimum estimates of the power dissipated by the spike are comparable to independent estimates of the dissipation associated with the entire steady state geodynamo. This suggests that geomagnetic spikes are either associated with rapid changes in magnetic energy or strong Lorentz forces.

  4. Optimized Conditioning of Activated Reactor Graphite

    SciTech Connect

    Tress, G.; Doehring, L.; Pauli, H.; Beer, H.-F.

    2002-02-25

    The research reactor DIORIT at the Paul Scherrer Institute was decommissioned in 1993 and is now being dismantled. One of the materials to be conditioned is activated reactor graphite, approximately 45 tons. A cost effective conditioning method has been developed. The graphite is crushed to less than 6 mm and added to concrete and grout. This graphite concrete is used as matrix for embedding dismantling waste in containers. The waste containers that would have been needed for separate conditioning and disposal of activated reactor graphite are thus saved. Applying the new method, the cost can be reduced from about 55 SFr/kg to about 17 SFr/kg graphite.

  5. Dependence of the high-latitude plasma irregularities on the auroral activity indices: a case study of 17 March 2015 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Cherniak, Iurii; Zakharenkova, Irina

    2015-09-01

    The magnetosphere substorm plays a crucial role in the solar wind energy dissipation into the ionosphere. We report on the intensity of the high-latitude ionospheric irregularities during one of the largest storms of the current solar cycle—the St. Patrick's Day storm of 17 March 2015. The database of more than 2500 ground-based Global Positioning System (GPS) receivers was used to estimate the irregularities occurrence and dynamics over the auroral region of the Northern Hemisphere. We analyze the dependence of the GPS-detected ionospheric irregularities on the auroral activity. The development and intensity of the high-latitude irregularities during this geomagnetic storm reveal a high correlation with the auroral hemispheric power and auroral electrojet indices (0.84 and 0.79, respectively). Besides the ionospheric irregularities caused by particle precipitation inside the polar cap region, evidences of other irregularities related to the storm enhanced density (SED), formed at mid-latitudes and its further transportation in the form of tongue of ionization (TOI) towards and across the polar cap, are presented. We highlight the importance accounting contribution of ionospheric irregularities not directly related with particle precipitation in overall irregularities distribution and intensity.

  6. Geomagnetic referencing in the arctic environment

    USGS Publications Warehouse

    Poedjono, B.; Beck, N.; Buchanan, A. C.; Brink, J.; Longo, J.; Finn, C.A.; Worthington, E.W.

    2011-01-01

    Geomagnetic referencing is becoming an increasingly attractive alternative to north-seeking gyroscopic surveys to achieve the precise wellbore positioning essential for success in today's complex drilling programs. However, the greater magnitude of variations in the geomagnetic environment at higher latitudes makes the application of geomagnetic referencing in those areas more challenging. Precise, real-time data on those variations from relatively nearby magnetic observatories can be crucial to achieving the required accuracy, but constructing and operating an observatory in these often harsh environments poses a number of significant challenges. Operational since March 2010, the Deadhorse Magnetic Observatory (DED), located in Deadhorse, Alaska, was created through collaboration between the United States Geological Survey (USGS) and a leading oilfield services supply company. DED was designed to produce real-time geomagnetic data at the required level of accuracy, and to do so reliably under the extreme temperatures and harsh weather conditions often experienced in the area. The observatory will serve a number of key scientific communities as well as the oilfield drilling industry, and has already played a vital role in the success of several commercial ventures in the area, providing essential, accurate data while offering significant cost and time savings, compared with traditional surveying techniques. Copyright 2011, Society of Petroleum Engineers.

  7. Geomagnetic referencing in the arctic environment

    USGS Publications Warehouse

    Podjono, Benny; Beck, Nathan; Buchanan, Andrew; Brink, Jason; Longo, Joseph; Finn, Carol A.; Worthington, E. William

    2011-01-01

    Geomagnetic referencing is becoming an increasingly attractive alternative to north-seeking gyroscopic surveys to achieve the precise wellbore positioning essential for success in today's complex drilling programs. However, the greater magnitude of variations in the geomagnetic environment at higher latitudes makes the application of geomagnetic referencing in those areas more challenging. Precise, real-time data on those variations from relatively nearby magnetic observatories can be crucial to achieving the required accuracy, but constructing and operating an observatory in these often harsh environments poses a number of significant challenges. Operational since March 2010, the Deadhorse Magnetic Observatory (DED), located in Deadhorse, Alaska, was created through collaboration between the United States Geological Survey (USGS) and a leading oilfield services supply company. DED was designed to produce real-time geomagnetic data at the required level of accuracy, and to do so reliably under the extreme temperatures and harsh weather conditions often experienced in the area. The observatory will serve a number of key scientific communities as well as the oilfield drilling industry, and has already played a vital role in the success of several commercial ventures in the area, providing essential, accurate data while offering significant cost and time savings, compared with traditional surveying techniques.

  8. Geomagnetic effects modelling for the PJM interconnection system. Part 2; Geomagnetically induced current study results

    SciTech Connect

    Prabhakara, F.S.; Hannett, L.N.; Ringlee, R.J. ); Ponder, J.Z. )

    1992-05-01

    The development of a computer program for calculation of geomagnetically induced current (GIC) and a GIC power system model for the Pennsylvania-New Jersey-Maryland Interconnection is described in this paper. Results of GIC for three different ionospheric source configurations are shown. A new method is presented for estimating GIC in unmetered parts of the system based on a few measurements and precalculated geomagnetic disturbance conditions. The use of an interactive, menu driven GIC program to study mitigation concepts including the effects of line outages, line series capacitors, transformer neutral blocking resistors and transformer neutral blocking capacitors is also presented.

  9. Geomagnetic storms: Potential economic impacts on electric utilities

    SciTech Connect

    Barnes, P.R.; Van Dyke, J.W.

    1991-03-20

    Geomagnetic storms associated with sunspot and solar flare activity can disturb communications and disrupt electric power. A very severe geomagnetic storm could cause a major blackout with an economic impact of several billion dollars. The vulnerability of electric power systems in the northeast United States will likely increase during the 1990s because of the trend of transmitting large amounts of power over long distance to meet the electricity demands of this region. A comprehensive research program and a warning satellite to monitor the solar wind are needed to enhance the reliability of electric power systems under the influence of geomagnetic storms. 7 refs., 2 figs., 1 tab.

  10. Investigating geomagnetic activity dependent sources of 100s of keV electrons in Earth's inner radiation belt using Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Turner, D. L.; O'Brien, T. P., III; Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; Baker, D. N.; Henderson, M. G.; Reeves, G. D.

    2015-12-01

    By providing an unprecedented level of reliability in particle flux observations at low L-shells, NASA's Van Allen Probes mission has yielded a series of discoveries and unanswered questions concerning the inner electron radiation belt. Two such discoveries are: 1) a sharp cutoff in the energy distribution of electrons at ~900 keV, such that fluxes of electrons with energies greater than ~900 keV are below the detectability threshold of the Van Allen Probes' MagEIS instruments and consistent with upper flux limits of multi-MeV electrons calculated using the Van Allen Probes' REPT instruments, and 2) that impulsive injections of up to several hundred keV electrons may act as an activity-dependent source of electrons in the slot and inner radiation belt. In this presentation, we discuss results from phase space density (PSD) analysis of inner zone electrons. Such analysis, which examines PSD as a function of the three adiabatic invariants, effectively removes adiabatic variations in the particle observations allowing one to better identify source and loss processes ongoing in the system. We demonstrate that impulsive injections do indeed act as a source of inner radiation belt electrons and, when combined with losses in the slot region, can result in peaked radial distributions of electron PSD in the inner zone. We briefly discuss the nature of these low-L injections, which penetrate inside the plasmasphere and display strong energy and species dependencies. By examining such injections throughout the Van Allen Probes era, we also i) determine the occurrence rate of injections as a function of electron energy (and first adiabatic invariant), geomagnetic activity level, and L-shell; ii) estimate the contribution of such injections to the inner belt population; and iii) investigate how such injections disrupt coherent banded flux structures in the inner zone known as "zebra stripes".

  11. A statistical study of the inner edge of the electron plasma sheet and the net convection potential as a function of geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Jiang, F.; Kivelson, M. G.; Walker, R. J.; Khurana, K. K.; Angelopoulos, V.; Hsu, T.

    2011-06-01

    A widely accepted explanation of the location of the inner edge of the electron plasma sheet and its dependence on electron energy is based on drift motions of individual particles. The boundary is identified as the separatrix between drift trajectories linking the tail to the dayside magnetopause (open paths) and trajectories closed around the Earth. A statistical study of the inner edge of the electron plasma sheet using THEMIS Electrostatic Analyzer plasma data from November 2007 to April 2009 enabled us to examine this model. Using a dipole magnetic field and a Volland-Stern electric field with shielding, we find that a steady state drift boundary model represents the average location of the electron plasma sheet boundary and reflects its variation with the solar wind electric field in the local time region between 21:00 and 06:00, except at high activity levels. However, the model does not reproduce the observed energy dispersion of the boundaries. We have also used the location of the inner edge of the electron plasma sheet to parameterize the potential drop of the tail convection electric field as a function of solar wind electric field (Esw) and geomagnetic activity. The range of Esw examined is small because the data were acquired near solar minimum. For the range of values tested (meaningful statistics only for Esw < 2 mV/m), reasonably good agreement is found between the potential drop of the tail convection electric field inferred from the location of the inner edge and the polar cap potential drop calculated from the model of Boyle et al. (1997).

  12. Hazards of geomagnetic storms

    USGS Publications Warehouse

    Herzog, D.C.

    1992-01-01

    Geomagnetic storms are large and sometimes rapid fluctuations in the Earth's magnetic field that are related to disturbances on the Sun's surface. Although it is not widely recognized, these transient magnetic disturbances can be a significant hazard to people and property. Many of us know that the intensity of the auroral lights increases during magnetic storms, but few people realize that these storms can also cause massive power outages, interrupt radio communications and satellite operations, increase corrosion in oil and gas pipelines, and lead to spuriously high rejection rates in the manufacture of sensitive electronic equipment. 

  13. A comparison of geomagnetic and solar effects on tropospheric circulation in the Northern Hemisphere in winter

    NASA Astrophysics Data System (ADS)

    Huth, Radan; Pokorná, Lucie; Bochníček, Josef; Davídkovová, Hana

    2010-05-01

    Our previous results on solar effects on tropospheric circulation in the Northern Hemisphere in winter, characterized i.a. by modes of low-frequency variability (teleconnections), are extended to the geomagnetic activity. The winter (December to March) months and 10-day periods are stratified by the geomagnetic activity into three classes, low, moderate, and high. The variability modes are determined in the 500 hPa geopotential height field by rotated principal component analysis separately in each class of geomagnetic activity. The effects of geomagnetic activity on winter mid-tropospheric variability modes are significant and considerably differ from those of solar activity. Under high geomagnetic activity, zonal modes (in particular North Atlantic Oscillation, East Atlantic mode, and West Pacific Oscillation) intensify and their eastern flanks become more meridional, which results in a weakened westerly circulation over central Europe. The effect of geomagnetic activity depends on the time scale: it is more pronounced for monthly than 10-day mean data. A time lag introduced between the geomagnetic forcing and tropospheric response contributes to a slight strengthening of the effects detected. The separate analysis conducted for days with a quiet or unsettled geomagnetic field only, suggests that most of the solar effects on tropospheric circulation are direct, that is, not mediated through geomagnetic activity. The research is supported by the Grant Agency of the Czech Academy of Sciences, project A300420805.

  14. Stochastic properties of the geomagnetic field across the 210 mm chain

    NASA Astrophysics Data System (ADS)

    Wanliss, J. A.; Shiokawa, K.; Yumoto, K.

    2013-12-01

    We explore the stochastic fractal qualities of the geomagnetic field from 210 mm ground-based magnetometers during quiet and active magnetospheric conditions. We search through 10 years of these data to find events that qualify. Quiet intervals are defined by Kp ≤ 1 for 1,440 consecutive minutes. Similarly, active intervals require Kp ≥ 4 for 1,440 consecutive minutes. The total for quiet intervals is ~4.3×106 minutes and 2×108 minutes for active data points. With this large number of events compiled we then characterize changes in the nonlinear statistics of the geomagnetic field via measurements of a fractal scaling exponent. A clear difference in statistical behavior during quiet and active intervals is implied through analysis of the scaling exponents; active intervals generally have larger values of scaling exponents. This means that although 210 mm data appears monofractal on shorter timescales, it is more properly described as a multifractional Brownian motion. Long-range statistical behavior of the geomagnetic field at a local observation site can be described as a multifractional Brownian motion, thus suggesting the statistical structure required of mathematical models of magnetospheric activity. We also find that low-latitudes have scaling exponents that are consistently larger than for high-latitudes.

  15. Financial Activity & Condition Taxpayer Summary (FACTS), 2002.

    ERIC Educational Resources Information Center

    Piotrowski, Craig; Moore, Anne

    The purpose of this Financial Activity & Condition Taxpayer Summary (FACTS) is to provide information about the Waukesha County Technical College (WCTC) for the 2002 fiscal year. The detailed report is divided into the following sections: (1) WCTC Board Members; (2) The President's Outlook; (3) Service Efforts and Accomplishments; (4) Brief…

  16. Financial Activity & Condition Taxpayer Summary, 1999.

    ERIC Educational Resources Information Center

    Piotrowski, Craig

    Provides a concise report on the financial position and operations of Waukesha County Technical College (WCTC) in Wisconsin for the fiscal year ended June 30, 1999. Contains the following items: the 1999 Financial Activity and Condition Taxpayer Summary report; a message from WCTC Board Members; a list of the WCTC Board Members; the President's…

  17. Geomagnetic Variations of Near-polar Regions and Human Health

    NASA Astrophysics Data System (ADS)

    Tchistova, Z. B.; Kutinov, Y. G.

    In polar region geomagnetic variations play active role to non-linear tectonic processes. This analysis is based on spatial-time spectral representation of geomagnetic variation and wave migration transformation. Many perturbations in electromagnetic fields may because by external factors (e.g. magnetic storms, ionosphere anomalies and other phenomena related to solar activity) "trigging" tectonic processes but having no direct relation to the processes of their preparation. Geophysical processes are responsible for perturbations in Earth's rotation and orientation on wide range of time-scale, from less than a day of millions of years. The geological structure of some sites of Earth's crust promotes occurrence of wave guides a number of geophysical fields (acoustic, seismic, electromagnetic), usually of transportation of acoustic, seismic, electromagnetic energy in Earth's crust are coincide spatially. During last 250 mln years Arctic Segment has been developing as an autonomous region with circumpolar zonality of geomagnetic fields, and mass - and-energy transfer in its bowlers as well as shitting of lithospheric plates and expansion of ocean are caused by rotation forces under of expanding planet. The dynamic structure of the geomagnetic variations may be characteriz ed by the variations of the order-chaos state. The order manifest itself in the rhythmic change of the medium state. Analysis of amplitude and phase of geomagnetic variations can be information on ecological state of regions. Geomagnetic variations is intrincically a multiscale process in time and space. One of the most important features of geomagnetic variations is multicyclic character, whish predetermined both extent and character of geomagnetic show, and specific features. Recently, there are collected many facts, show dependence between the processes in the Earth's biosphere, the elements of it, gelio- geo- physical and meteorological factors. The recent experimental data gives us opportunity

  18. Study of daytime vertical E × B drift velocities inferred from ground-based magnetometer observations of ΔH, at low latitudes under geomagnetically disturbed conditions

    NASA Astrophysics Data System (ADS)

    Subhadra Devi, P. K.; Unnikrishnan, K.

    2014-03-01

    In this study, 30 storm sudden commencement (SSC) events during the period 2001-2007 for which daytime vertical E × B drift velocities from JULIA radar, Jicamarca (geographic latitude 11.91°S, geographic longitude 283.11°E, 0.81°N dip latitude), Peru and ΔH component of geomagnetic field measured as the difference between the magnitudes of the horizontal (H) components between two magnetometers deployed at two different locations Jicamarca (geographic latitude 11.91°S, geographic longitude 283.11°E, 0.81°N dip latitude) and Piura (geographic latitude 5.21°S, geographic longitude 279.41°E, 6.81°N dip latitude), in Peru, were considered. It is observed that a positive correlation exists between peak value of daytime vertical E × B drift velocity and peak value of ΔH for the three consecutive days of SSC. A qualitative analysis made after selecting the peak values of daytime vertical E × B drift velocity and ΔH showed that 57% of the events have daytime vertical E × B drift velocity peak in the magnitude range 20-30 m/s and 63% of the events have ΔH peak in the range 80-100 nT. The maximum probable (45%) range of time of occurrence of peak value for both vertical E × B drift velocity and ΔH during the daytime hours were found to be the same, i.e., 10:00-12:00 LT. A strong positive correlation was also found to exist between the daytime vertical E × B drift velocity and ΔH for all the three consecutive days of SSC, for all the events considered. To establish a quantitative relationship between day time vertical E × B drift velocity and ΔH, linear and polynomial (order 2 and 3) regression analysis (Least Square Method (LSM)) were carried out, considering the fully disturbed day after the commencement of the storm as ‘disturbed period’ for the SSC events selected for analysis. The formulae indicating the relationship between daytime vertical E × B drift velocity and ΔH, for the ‘disturbed periods’, obtained through the regression analysis

  19. The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Gold, R. E.; Dodson-Prince, H. W.; Hedeman, E. R.; Roelof, E. C.

    1982-01-01

    Solar and interplanetary data are examined, taking into account the identification of the heliographic longitudes of the coronal source regions of high speed solar wind (SW) streams by Nolte and Roelof (1973). Nolte and Roelof have 'mapped' the velocities measured near earth back to the sun using the approximation of constant radial velocity. The 'Carrington carpet' for rotations 1597-1616 is shown in a graph. Coronal sources of high speed streams appear in the form of solid black areas. The contours of the stream sources are laid on 'evolutionary charts' of solar active region histories for the Southern and Northern Hemispheres. Questions regarding the interplay of active regions and solar wind are investigated, giving attention to developments during the years 1973, 1974, and 1975.

  20. The Development of a Dynamic Geomagnetic Cutoff Rigidity Model for the International Space Station

    NASA Technical Reports Server (NTRS)

    Smart, D. F.; Shea, M. A.

    1999-01-01

    We have developed a computer model of geomagnetic vertical cutoffs applicable to the orbit of the International Space Station. This model accounts for the change in geomagnetic cutoff rigidity as a function of geomagnetic activity level. This model was delivered to NASA Johnson Space Center in July 1999 and tested on the Space Radiation Analysis Group DEC-Alpha computer system to ensure that it will properly interface with other software currently used at NASA JSC. The software was designed for ease of being upgraded as other improved models of geomagnetic cutoff as a function of magnetic activity are developed.

  1. The Properties of Large Amplitude Whistler Mode Waves in the Magnetosphere: Propagation and Relationship with Geomagnetic Activity

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Wygant, J. R.; Goetz, K.; Breneman, A.; Kersten, K.

    2011-01-01

    Wepresent resultsof a studyof the characteristicsof very large amplitude whistler mode waves inside the terrestrial magnetosphere at radial distances of less than 15 RE using waveform capture data from the Wind spacecraft. We observed 247 whistler mode waves with at least one electric field component (105/247 had !80 mV/m peak!to!peak amplitudes) and 66 whistler mode waves with at least one search coil magnetic field component (38/66 had !0.8 nT peak!to!peak amplitudes). Wave vectors determined from events with three magnetic field components indicate that 30/46 propagate within 20 of the ambient magnetic field, though some are more oblique (up to "50 ). No relationship was observed between wave normal angle and GSM latitude. 162/247 of the large amplitude whistler mode waves were observed during magnetically active periods (AE > 200 nT). 217 out of 247 total whistler mode waves examined were observed inside the radiation belts. We present a waveform capture with the largest whistler wave magnetic field amplitude (^8 nT peak!to!peak) ever reported in the radiation belts. The estimated Poynting flux magnitude associated with this wave is ^300 mW/m2, roughly four orders of magnitude above estimates from previous satellite measurements. Such large Poynting flux values are consistent with rapid energization of electrons.

  2. Bayesian inference in geomagnetism

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1988-01-01

    The inverse problem in empirical geomagnetic modeling is investigated, with critical examination of recently published studies. Particular attention is given to the use of Bayesian inference (BI) to select the damping parameter lambda in the uniqueness portion of the inverse problem. The mathematical bases of BI and stochastic inversion are explored, with consideration of bound-softening problems and resolution in linear Gaussian BI. The problem of estimating the radial magnetic field B(r) at the earth core-mantle boundary from surface and satellite measurements is then analyzed in detail, with specific attention to the selection of lambda in the studies of Gubbins (1983) and Gubbins and Bloxham (1985). It is argued that the selection method is inappropriate and leads to lambda values much larger than those that would result if a reasonable bound on the heat flow at the CMB were assumed.

  3. Harmonics of 60 Hz in power systems caused by geomagnetic disturbances. [Manitoba

    NASA Technical Reports Server (NTRS)

    Hayashi, K.; Oguti, T.; Watanabe, T.; Tsuruda, K.; Kokubun, S.; Horita, R. E.

    1979-01-01

    Simultaneous VLF/ULF observations carried out near Winnipeg, Manitoba show that geomagnetic disturbances control the behavior of harmonics of 60 Hz man-made electric power. The harmonics of 60 Hz detected by the VLF receiver are at multiples of 180 Hz, indicating that they originated from a 3 phase ac power system. Under geomagnetically quiet conditions, only odd harmonics of 70 Hz were detected. In disturbed conditions, both odd and even harmonics were excited. The strength of each harmonic changed concurrently with geomagnetic pulsation (ULF) activity. These findings seem to indicate that a portion of telluric currents shunted into the power line system through the neutrals of the Y-connected transformers give rise to a dc bias to the transformer core materials and that it distorts their hysteresis loops, activating harmonics of 60 Hz power. A mathematical proof is given that a hysteresis loop having a point of symmetry generates odd harmonics only, whereas loops lacking in point-symmetry generally give rise to both odd and even harmonics. A general formula was obtained to calculate the strength of each harmonic based on the shape of the hysteresis loop.

  4. Recurrent geomagnetic storms and relativistic electron enhancements in the outer magnetosphere: ISTP coordinated measurements

    SciTech Connect

    Baker, D.N.; Li, X.; Turner, N.; Allen, J.H.; Blake, J.B.; Sheldon, R.B.; Spence, H.E.; Belian, R.D.; Reeves, G.D.; Kanekal, S.G.; Lepping, R.P.; Ogilvie, K.; Mewaldt, R.A.; Onsager, T.; Singer, H.J.

    1997-07-01

    New, coordinated measurements from the International Solar-Terrestrial Physics (ISTP) constellation of spacecraft are presented to show the causes and effects of recurrent geomagnetic activity during recent solar minimum conditions. It is found using WIND and POLAR data that even for modest geomagnetic storms, relativistic electron fluxes are strongly and rapidly enhanced within the outer radiation zone of the Earth{close_quote}s magnetosphere. Solar wind data are utilized to identify the drivers of magnetospheric acceleration processes. Yohkoh solar soft X-ray data are also used to identify the solar coronal holes that produce the high-speed solar wind streams which, in turn, cause the recurrent geomagnetic activity. It is concluded that even during extremely quiet solar conditions (sunspot minimum) there are discernible coronal holes and resultant solar wind streams which can produce intense magnetospheric particle acceleration. As a practical consequence of this Sun-Earth connection, it is noted that a long-lasting E{gt}1MeV electron event in late March 1996 appears to have contributed significantly to a major spacecraft (Anik E1) operational failure.{copyright} 1997 American Geophysical Union

  5. The combined effects of electrojet strength and the geomagnetic activity (Kp-index) on the post sunset height rise of the F-layer and its role in the generation of ESF during high and low solar activity periods

    NASA Astrophysics Data System (ADS)

    Tulasi Ram, S.; Rama Rao, P. V. S.; Prasad, D. S. V. V. D.; Niranjan, K.; Raja Babu, A.; Sridharan, R.; Devasia, C. V.; Ravindran, Sudha

    2007-10-01

    Several investigations have been carried out to identify the factors that are responsible for the day-to-day variability in the occurrence of equatorial spread-F (ESF). But the precise forecasting of ESF on a day-to-day basis is still far from reality. The nonlinear development and the sustenance of ESF/plasma bubbles is decided by the background ionospheric conditions, such as the base height of the F-layer (h'F), the electron density gradient (dN/dz), maximum ionization density (Nmax), geomagnetic activity and the neutral dynamics. There is increasing evidence in the literature during the recent past that shows a well developed Equatorial Ionization Anomaly (EIA) during the afternoon hours contributes significantly to the initiation of ESF during the post-sunset hours. Also, there exists a good correlation between the Equatorial Ionization Anomaly (EIA) and the Integrated Equatorial ElectroJet (IEEJ) strength, as the driving force for both is the same, namely, the zonal electric field at the equator. In this paper, we present a linear relationship that exists between the daytime integrated equatorial electrojet (IEEJ) strength and the maximum elevated height of the F-layer during post-sunset hours (denoted as peak h'F). An inverse relationship that exists between the 6-h average Kp-index prior to the local sunset and the peak h'F of the F-layer is also presented. A systematic study on the combined effects of the IEEJ and the average Kp-index on the post-sunset, peak height of the F-layer (peak h'F), which controls the development of ESF/plasma bubbles, is carried out using the ionosonde data from an equatorial station, Trivandrum (8.47° N, 76.91° E, dip.lat. 0.5° N), an off-equatorial station, SHAR (13.6° N, 79.8° E, dip.lat. 10.8° N) and VHF scintillations (244 MHz) observed over a nearby low-latitude station, Waltair (17.7° N, 83.3° E, dip.lat. 20° N). From this study, it has been found that the threshold base height of the F-layer at the equator for

  6. Artificial static and geomagnetic field interrelated impact on cardiovascular regulation.

    PubMed

    Gmitrov, Juraj; Ohkubo, Chiyoji

    2002-07-01

    Spreading evidence suggests that environmental and artificial magnetic fields have a significant impact on cardiovascular system. The modulation of cardiovascular regulatory mechanisms may play a key role in observed effects. The objective was to study interrelated impacts of artificial static magnetic field (SMF) and natural geomagnetic field (GMF) on arterial baroreceptors. We studied baroreflex sensitivity (BRS) in conscious rabbits before and after 40 min of sham (n = 20) or application of Nd2-Fe14-B alloy magnets (n = 26) to the sinocarotid baroreceptor region in conjunction with GMF disturbance during the actual experiment, determined by K- and A(k)-indexes from a local geomagnetic observatory. SMF at the position of baroreceptors was 0.35 T. BRS was estimated from peak responses of mean arterial pressure (MAP) and heart rate expressed as percentages of the resting values preceding each pair of pressure (phenylephrine) and depressor drug (nitroprusside) injections. We observed a significant increase in BRS for the nitroprusside depressor test (0.78 +/- 0.1 vs. 1.15 +/- 0.14 bpm/mmHg%, initial value vs. SMF exposure, P <.0002) and a tendency for phenylephrine pressor test to increase in BRS. Prior to SMF exposure, a significant positive correlation was found between actual K index values and MAP (t = 2.33, P =.025, n = 46) and a negative correlation of the K index with BRS (t = -3.6, P =.001, n = 46). After SMF exposure we observed attenuation of the geomagnetic disturbance induced a decrease in BRS. Clinical trials should be performed to support these results, but there is a strong expectation that 0.35 T SMF local exposure to sinocarotid baroreceptors will be effective in cardiovascular conditions with arterial hypertension and decreased BRS, due to a favorable SMF effect on the arterial baroreflex. Magnets to the sinocarotid triangle along with modification of the pharmacotherapy for hypertension should be especially effective on days with intense

  7. Reply to comment on geomagnetic activity associated with earth passage of interplanetary shock disturbances and coronal mass ejections by J. T. Gosling, D. J. McComas, J. L. Phillips, and S. J. Bame

    SciTech Connect

    Gosling, J.T.; McComas, D.J.; Phillips, J.L.; Bame, S.J. )

    1993-02-01

    It is clear that the preceding comment is based on a serious misunderstanding of the conclusions arrived at in our 1991 paper. We welcome this opportunity to clear up these misunderstandings. Contrary to inferences in the Tsurutani and Gonzalez comment we have not advocated that solar wind speed at 1 AU is a more important factor than a strong southward interplanetary magnetic field (IMF) in stimulating geomagnetic activity, although it is a factor. Our primary emphasis in the abstract and the discussion section of the 1991 paper was not on high flow speeds at 1 AU and the role of high 1 AU speed in coupling solar wind energy to the magnetosphere, but rather on the initial speed of coronal mass ejections (CMES) close to the Sun and the role of high initial speeds in producing strong southward magnetic fields (negative B[sub z]) in interplanetary space via compression and draping. As we have elaborated extensively on this point in the discussion section of the paper as well as in a previous paper, it is difficult to understand how Tsurutani and Gonzalez could so seriously misconstrue our conclusions. A careful reading of our 1991 paper, as well as our other recent papers concerning CMEs in the solar wind at 1 AU, reveals that, in contrast to inferences in the Tsurutani and Gonzalez comment, we have repeatedly stressed the importance of a strong southward IMF at 1 AU for producing geomagnetic activity. Indeed, the Gosling and McComas and McComas et al. papers on field line draping were explicitly directed toward explaining prolonged intervals of strong southward fields within the shocked plasma ahead of fast CMEs (and the corresponding effect on geomagnetic activity). We have also explicitly noted on a number of occasions the importance of reconnection at the dayside magnetopause as the prime means of transferring solar wind energy to the magnetosphere. 13 refs.

  8. Geomagnetic effects on the average surface temperature

    NASA Astrophysics Data System (ADS)

    Ballatore, P.

    Several results have previously shown as the solar activity can be related to the cloudiness and the surface solar radiation intensity (Svensmark and Friis-Christensen, J. Atmos. Sol. Terr. Phys., 59, 1225, 1997; Veretenenkoand Pudovkin, J. Atmos. Sol. Terr. Phys., 61, 521, 1999). Here, the possible relationships between the averaged surface temperature and the solar wind parameters or geomagnetic activity indices are investigated. The temperature data used are the monthly SST maps (generated at RAL and available from the related ESRIN/ESA database) that represent the averaged surface temperature with a spatial resolution of 0.5°x0.5° and cover the entire globe. The interplanetary data and the geomagnetic data are from the USA National Space Science Data Center. The time interval considered is 1995-2000. Specifically, possible associations and/or correlations of the average temperature with the interplanetary magnetic field Bz component and with the Kp index are considered and differentiated taking into account separate geographic and geomagnetic planetary regions.

  9. Possible influence of solar extreme events and related geomagnetic disturbances on human cardio-vascular state: Results of collaborative Bulgarian-Azerbaijani studies

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.; Mustafa, F. R.; Stoilova, I.; Babayev, E. S.; Kazimov, E. A.

    2009-02-01

    This collaborative study is based on the analysis and comparison of results of coordinated experimental investigations conducted in Bulgaria and Azerbaijan for revealing a possible influence of solar activity changes and related geomagnetic activity variations on the human cardio-vascular state. Arterial blood pressure and heart rate of 86 healthy volunteers were measured on working days during a period of comparatively high solar and geomagnetic activity (2799 measurements in autumn 2001 and spring 2002) in Sofia. Daily experimental investigations of parameters of cardio-vascular health state were performed in Azerbaijan with a permanent group of examined persons. Heart rate and electrocardiograms were digitally registered (in total 1532 records) for seven functionally healthy persons on working days and Saturdays, in the Laboratory of Heliobiology at the Medical Center INAM in Baku, from 15.07.2006 to 13.11.2007. Obtained digital recordings were subjected to medical, statistical and spectral analyses. Special attention was paid to effects of solar extreme events, particularly those of November 2001 and December 2006. The statistical method of the analysis of variance (ANOVA) and post hoc analysis were applied to check the significance of the influence of geomagnetic activity on the cardio-vascular parameters under consideration. Results revealed statistically significant increments for the mean systolic and diastolic blood pressure values of the group with geomagnetic activity increase. Arterial blood pressure values started increasing two days prior to geomagnetic storms and kept their high values up to two days after the storms. Heart rate reaction was ambiguous and not significant for healthy persons examined (for both groups) under conditions with geomagnetic activity changes. It is concluded that heart rate for healthy persons at middle latitudes can be considered as a more stable physiological parameter which is not so sensitive to environmental changes

  10. Statistical analysis of extreme values for geomagnetic and geoelectric field variations for Canada

    NASA Astrophysics Data System (ADS)

    Nikitina, Lidia; Trichtchenko, Larisa; Boteler, David

    2016-04-01

    Disturbances of the geomagnetic field produced by space weather events cause variable geoelectric fields at Earth's surface which drive electric currents in power systems, resulting in hazardous impacts on electric power transmission. In extreme cases, as during the magnetic storm in March 13, 1989, this can result in burnt-out transformers and power blackouts. To make assessment of geomagnetic and geoelectric activity in Canada during extreme space weather events, extreme value statistical analysis has been applied to more than 40 years of magnetic data from the Canadian geomagnetic observatories network. This network has archived digital data recordings for observatories located in sub-auroral, auroral, and polar zones. Extreme value analysis was applied to hourly ranges of geomagnetic variations as an index of geomagnetic activity and to hourly maximum of rate-of-change of geomagnetic field. To estimate extreme geoelectric fields, the minute geomagnetic data were used together with Earth conductivity models for different Canadian locations to calculate geoelectric fields. The extreme value statistical analysis was applied to hourly maximum values of the horizontal geoelectric field. This assessment provided extreme values of geomagnetic and geoelectric activity which are expected to happen once per 50 years and once per 100 years. The results of this analysis are designed to be used to assess the geomagnetic hazard to power systems and help the power industry mitigate risks from extreme space weather events.

  11. Geomagnetic Reversals during the Phanerozoic.

    PubMed

    McElhinny, M W

    1971-04-01

    An antalysis of worldwide paleomagnetic measurements suggests a periodicity of 350 x 10(6) years in the polarity of the geomagnetic field. During the Mesozoic it is predominantly normal, whereas during the Upper Paleozoic it is predominantly reversed. Although geomagnetic reversals occur at different rates throughout the Phanerozoic, there appeaars to be no clear correlation between biological evolutionary rates and reversal frequency. PMID:17735224

  12. The response of European Daphnia magna Straus and Australian Daphnia carinata King to changes in geomagnetic field.

    PubMed

    Krylov, Viacheslav V; Bolotovskaya, Irina V; Osipova, Elena A

    2013-03-01

    This study investigates the effects of lifelong exposure to reversed geomagnetic and zero geomagnetic fields (the latter means absence of geomagnetic field) on the life history of Daphnia carinata King from Australia and Daphnia magna Straus from Europe. Considerable deviation in the geomagnetic field from the usual strength, leads to a decrease in daphnia size and life span. Reduced brood sizes and increased body length of neonates are observed in D. magna exposed to unusual magnetic background. The most apparent effects are induced by zero geomagnetic field in both species of Daphnia. A delay in the first reproduction in zero geomagnetic field is observed only in D. magna. No adaptive maternal effects to reversed geomagnetic field are found in a line of D. magna maintained in these magnetic conditions for eight generations. Integrally, the responses of D. magna to unusual geomagnetic conditions are more extensive than that in D. carinata. We suggest that the mechanism of the effects of geomagnetic field reversal on Daphnia may be related to differences in the pattern of distribution of the particles that have a magnetic moment, or to moving charged organic molecules owing to a change in combined outcome and orientation of the geomagnetic field and Earth's gravitational field. The possibility of modulation of self-oscillating processes with changes in geomagnetic field is also discussed.

  13. The response of European Daphnia magna Straus and Australian Daphnia carinata King to changes in geomagnetic field.

    PubMed

    Krylov, Viacheslav V; Bolotovskaya, Irina V; Osipova, Elena A

    2013-03-01

    This study investigates the effects of lifelong exposure to reversed geomagnetic and zero geomagnetic fields (the latter means absence of geomagnetic field) on the life history of Daphnia carinata King from Australia and Daphnia magna Straus from Europe. Considerable deviation in the geomagnetic field from the usual strength, leads to a decrease in daphnia size and life span. Reduced brood sizes and increased body length of neonates are observed in D. magna exposed to unusual magnetic background. The most apparent effects are induced by zero geomagnetic field in both species of Daphnia. A delay in the first reproduction in zero geomagnetic field is observed only in D. magna. No adaptive maternal effects to reversed geomagnetic field are found in a line of D. magna maintained in these magnetic conditions for eight generations. Integrally, the responses of D. magna to unusual geomagnetic conditions are more extensive than that in D. carinata. We suggest that the mechanism of the effects of geomagnetic field reversal on Daphnia may be related to differences in the pattern of distribution of the particles that have a magnetic moment, or to moving charged organic molecules owing to a change in combined outcome and orientation of the geomagnetic field and Earth's gravitational field. The possibility of modulation of self-oscillating processes with changes in geomagnetic field is also discussed. PMID:23320498

  14. Relationship between isolated sleep paralysis and geomagnetic influences: a case study.

    PubMed

    Conesa, J

    1995-06-01

    This preliminary report, of a longitudinal study, looks at the relationship between geomagnetic activity and the incidence of isolated sleep paralysis over a 23.5-mo. period. The author, who has frequently and for the last 24 years experienced isolated sleep paralysis was the subject. In addition, incidence of lucid dreaming, vivid dreams, and total dream frequency were looked at with respect to geomagnetic activity. The data were in the form of dream-recall frequency recorded in a diary. These frequency data were correlated with geomagnetic activity k-index values obtained from two observatories. A significant correlation was obtained between periods of local geomagnetic activity and the incidence of isolated sleep paralysis. Specifically, periods of relatively quiet geomagnetic activity were significantly associated with an increased incidence of episodes. PMID:7478886

  15. Relationship between isolated sleep paralysis and geomagnetic influences: a case study.

    PubMed

    Conesa, J

    1995-06-01

    This preliminary report, of a longitudinal study, looks at the relationship between geomagnetic activity and the incidence of isolated sleep paralysis over a 23.5-mo. period. The author, who has frequently and for the last 24 years experienced isolated sleep paralysis was the subject. In addition, incidence of lucid dreaming, vivid dreams, and total dream frequency were looked at with respect to geomagnetic activity. The data were in the form of dream-recall frequency recorded in a diary. These frequency data were correlated with geomagnetic activity k-index values obtained from two observatories. A significant correlation was obtained between periods of local geomagnetic activity and the incidence of isolated sleep paralysis. Specifically, periods of relatively quiet geomagnetic activity were significantly associated with an increased incidence of episodes.

  16. The Geomagnetic Control Concept of The Ionospheric Long- Term Trends

    NASA Astrophysics Data System (ADS)

    Mikhailov, A. V.

    The geomagnetic control concept has been developed to explain long-term trends of the electron concentration in the F2 and E ionospheric regions. Periods with negative and positive foF2, hmF2 and foE trends correspond to the periods of increasing or decreasing geomagnetic activity with the turning points around the end of 1950s, 1960s, and 1980s where trends change their signs. Strong latitudinal and diurnal variations revealed for the foF2 and hmF2 trends can be explained by neutral composition, temperature and thermospheric wind changes. Particle precipitation is important in the auroral zone. The newly proposed concept proceeds from a natural origin of the F2-layer trends rather than an artificial one related to the greenhouse effect. Using the proposed method a very long-term foF2 and foE trends related with general increase of geomagnetic activity in the 20th century has been revealed for the first time. The firstly revealed relationship of the foE trends with geomagnetic activity is due to nitric oxide variations at the E-region heights. This "natural" relationship of the foE trends with geomagnetic activity breaks down around 1970 on many stations presumably due to chemical polution of the upper atmosphere. The increasing rate of rocket and satellite launchings in the late 1960s is considered as a reason.

  17. Characterization and diagnostic methods for geomagnetic auroral infrasound waves

    NASA Astrophysics Data System (ADS)

    Oldham, Justin J.

    Infrasonic perturbations resulting from auroral activity have been observed since the 1950's. In the last decade advances in infrasonic microphone sensitivity, high latitude sensor coverage, time series analysis methods and computational efficiency have elucidated new types of auroral infrasound. Persistent periods of infrasonic activity associated with geomagnetic sub-storms have been termed geomagnetic auroral infrasound waves [GAIW]. We consider 63 GAIW events recorded by the Fairbanks, AK infrasonic array I53US ranging from 2003 to 2014 and encompassing a complete solar cycle. We make observations of the acoustic features of these events alongside magnetometer, riometer, and all-sky camera data in an effort to quantify the ionospheric conditions suitable for infrasound generation. We find that, on average, the generation mechanism for GAIW is confined to a region centered about ~60 0 longitude east of the anti-Sun-Earth line and at ~770 North latitude. We note furthermore that in all cases considered wherein imaging riometer data are available, that dynamic regions of heightened ionospheric conductivity periodically cross the overhead zenith. Consistent features in concurrent magnetometer conditions are also noted, with irregular oscillations in the horizontal component of the field ubiquitous in all cases. In an effort to produce ionosphere based infrasound free from the clutter and unknowns typical of geophysical observations, an experiment was undertaken at the High Frequency Active Auroral Research Program [HAARP] facility in 2012. Infrasonic signals appearing to originate from a source region overhead were observed briefly on 9 August 2012. The signals were observed during a period when an electrojet current was presumed to have passed overhead and while the facilities radio transmitter was periodically heating the lower ionosphere. Our results suggest dynamic auroral electrojet currents as primary sources of much of the observed infrasound, with

  18. Persulfate persistence under thermal activation conditions.

    PubMed

    Johnson, Richard L; Tratnyek, Paul G; Johnson, Reid O'Brien

    2008-12-15

    Contaminant destruction with in situ chemical oxidation (ISCO) using persulfate (peroxydisulfate, S2O8(2-)) can be enhanced by activation, which increases the rate of persulfate decomposition to sulfate radicals (SO4*-). This step initiates a chain of radical reactions involving species (including SO4*- and OH*) that oxidize contaminants more rapidly than persulfate does directly. Among current activation methods, thermal activation is the least well studied. Combining new data for environmentally relevant conditions with previously published data, we have computed three sets of Arrhenius parameters (In A and Eact) that describe the rate of persulfate decomposition in homogeneous solutions over a wide range of temperature and pH. The addition of soil increases the decomposition rate of persulfate due to reactions with organic matter and possibly mineral surfaces, but the kinetics are still pseudo-first-order in persulfate and conform to the Arrhenius model. A series of respike experiments with soil at 70 degrees C demonstrate that once the oxidant demand is met, reaction rates return to values near those observed in the homogeneous solution case. However, even after the oxidant demand is met, the relatively short lifetime of the persulfate at elevated temperatures (e.g., >50 degrees C) will limit the delivery time over which persulfate can be effective. PMID:19174915

  19. Effects of magnetic fields produced by simulated and real geomagnetic storms on rats

    NASA Astrophysics Data System (ADS)

    Martínez-Bretón, J. L.; Mendoza, B.

    2016-03-01

    In this paper we report experiments of arterial pressure (AP) measurements of ten Wistar rats subjected to geomagnetic field changes and to artificially stimulated magnetic field variations. Environmental electromagnetic effects were screened using a semianechoic chamber, which allowed us to discern the effects associated with geomagnetic storms. We stimulated the subjects with a linear magnetic profile constructed from the average changes of sudden storm commencement (SSC) and principal phases of geomagnetic storms measured between 1996 and 2008 with Dst ⩽ -100 nT. Although we found no statistically significant AP variations, statistically significant AP changes were found when a geomagnetic storm occurred during the experimental period. Using the observed geomagnetic storm variations to construct a geomagnetic profile to stimulate the rats, we found that the geomagnetic field variations associated to the SSC day were capable of increasing the subjects AP between 7% and 9% from the reference value. Under this magnetic variation, the subjects presented a notably restless behavior not seen under other conditions. We conclude that even very small changes in the geomagnetic field associated with a geomagnetic storm can produce a measurable and reproducible physiological response.

  20. The Lewis Research Center geomagnetic substorm simulation facility

    NASA Technical Reports Server (NTRS)

    Berkopec, F. D.; Stevens, N. J.; Sturman, J. C.

    1977-01-01

    A simulation facility was established to determine the response of typical spacecraft materials to the geomagnetic substorm environment and to evaluate instrumentation that will be used to monitor spacecraft system response to this environment. Space environment conditions simulated include the thermal-vacuum conditions of space, solar simulation, geomagnetic substorm electron fluxes and energies, and the low energy plasma environment. Measurements for spacecraft material tests include sample currents, sample surface potentials, and the cumulative number of discharges. Discharge transients are measured by means of current probes and oscilloscopes and are verified by a photomultiplier. Details of this facility and typical operating procedures are presented.

  1. a Millennium of Geomagnetism

    NASA Astrophysics Data System (ADS)

    Stern, David P.

    2002-11-01

    The history of geomagnetism began around the year 1000 with the discovery in China of the magnetic compass. Methodical studies of the Earth's field started in 1600 with William Gilbert's De Magnete [Gilbert, 1600] and continued with the work of (among others) Edmond Halley, Charles Augustin de Coulomb, Carl Friedrich Gauss, and Edward Sabine. The discovery of electromagnetism by Hans Christian Oersted and André-Marie Ampére led Michael Faraday to the notion of fluid dynamos, and the observation of sunspot magnetism by George Ellery Hale led Sir Joseph Larmor in 1919 to the idea that such dynamos could sustain themselves naturally in convecting conducting fluids. From that came modern dynamo theory, of both the solar and terrestrial magnetic fields. Paleomagnetic studies revealed that the Earth's dipole had undergone reversals in the distant past, and these became the critical evidence in establishing plate tectonics. Finally, the recent availability of scientific spacecraft has demonstrated the intricacy of the Earth's distant magnetic field, as well as the existence of magnetic fields associated with other planets and with satellites in our solar system.

  2. Analysis of geomagnetic data and cosmic ray variations in periods of magnetic perturbations

    NASA Astrophysics Data System (ADS)

    Mandrikova, Oksana; Zalyaev, Timur; Solovev, Igor; Shevtsov, Boris

    indent=0.63cm In the present paper we have suggested a model of the geomagnetic field variation, which allows us to present the characteristic variation of the field and local perturbations formed in periods of increased geomagnetic activity. The model is based on wavelets and has the following form: [ f(t)= sum_n c_{j,n} phi_{j,n} + sum_{(j_{dist},n)in I_1} d_{j_{dist},n}Psi_{j_{dist},n}(t) + sum_{(j_{dist},n)in I_2} d_{j_{dist},n}Psi_{j_{dist},n}(t) + e(t) ] where component sum_n c_{j,n} phi_{j,n} presents the characteristic variation; component \\sum_{(j_{dist},n)in I_1} d_{j_{dist},n}Psi_{j_{dist},n}(t) presents weak geomagnetic perturbations; component \\sum_{(j_{dist},n)in I_2} d_{j_{dist},n}Psi_{j_{dist},n}(t) presents strong geomagnetic perturbations; j is the scale; I_1, I_2 are the sets of indices; e(t) is the noise; Psi_j = \\{Psi_{j,n}\\}_{n in Z} is the wavelet basis; phi_j = \\{phi_{j,n}\\}_{n in Z} is the scaling function; c_{j,n}=< f, phi_{j,n} > ,d_{j,n}=< f, Psi_{j,n} >. Using the proposed model we have developed a technique of identifying the characteristic variation of the geomagnetic field (in periods of quiet magnetosphere) and components presenting different conditions of the field in periods of perturbations. The technique can be used for various data registration stations and is useful for studying the dynamics of electric current systems in the magnetosphere, the interaction between such systems, and their spatial and temporal distribution. We have also created special rules for estimating the storminess degree of the geomagnetic field. The suggested theoretical tools allow us to determine time points when geomagnetic perturbations arise and to obtain quantitative estimates of the storminess degree. Furthermore, it is also possible to implement these rules in the automatic mode. The theoretical tools mentioned above are also aimed at developing and improving mathematical tools for estimating and monitoring the condition of the geomagnetic

  3. Comment on geomagnetic activity associated with earth passage of interplanetary shock disturbances and coronal mass ejections by J. T. Gosling, D. J. McComas, J. L. Phillips, and S. J. Bame

    SciTech Connect

    Tsurutani, B.T. ); Gonzalez, W.D. )

    1993-02-01

    Gosling et al. have presented a very nice set of statistical data on solar wind driver gases (CMEs), interplanetary shocks, solar wind velocities, magnetic field magnitudes and B[sub z] values, and geomagnetic activity (Kp). The statistics are quite nice and similar to our own. The authors have no questions or comments concerning these. The authors note that Gosling et al. have one conclusion that is substantially different than prior work, however. In the last sentence of their abstract, they state, [open quotes]The initial speed of a CME close to the Sun appears to be the most crucial factor in determining if an earthward directed event will be effective in exciting a large geomagnetic disturbance.[close quotes] This is an unusual claim and goes quite contrary to prior perceptions of the interplanetary cause of magnetic storms, big and small. If this point is indeed correct it will be a big revelation to magnetospheric researchers. However, in looking at their paper in detail, the authors feel the statistical data that they presented do not support this claim. In this comment the authors will try to help clarify this issue and attempt to bring the Gosling et al. statistics and prior results into accord. 28 refs.

  4. Solar coronal holes as sources of recurrent geomagnetic disturbances

    NASA Technical Reports Server (NTRS)

    Neupert, W. M.; Pizzo, V.

    1974-01-01

    Observations of the solar corona by Oso 7 have been used in a superposed epoch analysis to study the relationships between classes of coronal features and geomagnetic activity. Both bright coronal regions and regions of less than average brightness were investigated. It was found that for the period from January 1972 through January 1973, a significant enhancement in geomagnetic activity occurred 2-3 days after central meridian passage of large coronal holes that extended to within 5 deg of the solar subearth point when they were on the meridian. Large coronal holes appear to satisfy the requirements for 'M regions' which were hypothesized to be responsible for recurrent geomagnetic disturbances (Bartels, 1934). If solar wind high-speed streams originate preferentially in these regions, their velocity at the base of the corona will be substantially higher than that expected from an axisymmetric solar wind model.

  5. Energy Dependent Responses of Relativistic Electron Fluxes in the Outer Radiation Belt to Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Xie, L.

    2015-12-01

    Geomagnetic storms can either increase 4 or decrease relativistic electron fluxes in the outer radiation belt. A statistical survey of 84 isolated storms demonstrates that geomagnetic storms preferentially decrease relativistic electron fluxes at higher energies while flux enhancements are more common at lower energies. In about 87% of the storms, 0.3-2.5 MeV electrons fluxes show increase, whereas 2.5-14 MeV electron fluxes increase in only 35% of the storms. Superposed epoch analyses suggest that such 'energy dependent' behavior of electrons preferably occurs during conditions of high solar wind density which is favorable to generate magnetospheric electromagnetic ion cyclotron (EMIC) waves and these 'energy dependent' events are associated with relatively weaker chorus activities. We have examined one of the cases where observed EMIC waves can resonate effectively with >2.5 MeV electrons and scatter them into the atmosphere. The correlation study further illustrates that electron flux drop-outs during storm main phases do not correlate well with the flux build-up during storm recovery phases. We suggest that a combination of efficient EMIC-induced scattering and weaker chorus-driven acceleration provide a viable candidate for the energy dependent responses of outer radiation belt relativistic electrons to geomagnetic storms. These results are of great interest to both understanding of the radiation belt dynamics and applications in space weather.

  6. Geomagnetic observations on tristan da cunha, south atlantic ocean

    USGS Publications Warehouse

    Matzka, J.; Olsen, N.; Maule, C.F.; Pedersen, L.W.; Berarducci, A.M.; Macmillan, S.

    2009-01-01

    Few geomagnetic ground observations exist of the Earth's strongest core field anomaly, the South Atlantic Anomaly (SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa and South America at 37?? 05' S, 12?? 18' W, is therefore of crucial importance. We have conducted several sets of repeat station measurements during magnetically quiet conditions (Kp 2o or less) in 2004. The procedures are described and the results are compared to those from earlier campaigns and to the predictions of various global field models. Features of the local crustal bias field and the solar quiet daily variation are discussed. We also evaluate the benefit of continuous magnetic field recordings from Tristan da Cunha, and argue that such a data set is a very valuable addition to geomagnetic satellite data. Recently, funds were set up to establish and operate a magnetometer station on Tristan da Cunha during the Swarm magnetic satellite mission (2011-2014).

  7. Electron Radiation Belt Dropouts in the Absence of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Morley, S.; Henderson, M. G.; Steinberg, J. T.; Turner, D. L.; Li, W.

    2015-12-01

    Most observational studies of electron radiation belt dropouts have presented losses occurring during geomagnetic storms. Some statistical analyses of flux dropouts have included non-storm time events, but examples of non-storm time dropouts are still rarities in the literature. A small, but growing, body of work has led to the current understanding that radiation belt dynamics are not always coupled with geomagnetic storms, and that a number of key features are associated with dropouts: solar wind dynamic pressure tends to be high; the interplanetary magnetic field tends to be southward. We present three case studies of dropouts that occurred under quiet geomagnetic conditions and examine the dynamics of the electron phase spece density, and flux, over a wide range of L using Van Allen Probes and other satellites. The solar wind driving each dropout is shown to have a different categorization, and we investigate the role of substorms in non-storm time radiation belt dynamics.

  8. Energy dependence of relativistic electron flux variations in the outer radiation belt during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Xiong, Ying; Xie, Lun; Li, Jinxing; Fu, Suiyan; Pu, Zuyin; Chen, Lunjin; Ni, Binbin; Li, Wen

    2015-04-01

    Geomagnetic storms can either increase or decrease relativistic electron fluxes in the outer radiation belt, depending on the delicate competition between electron energization and loss processes. Despite the well-known "energy independent" prototype in which electron fluxes enhance after geomagnetic storms at all energies, we present observations of "energy dependent" events, i.e., post-storm electron fluxes at lower energies (0.3-2.5 MeV, measured by MEPED/POES) recover or even exceed the pre-storm level, while electron fluxes at higher energies (2.5-14 MeV, measured by PET/SAMPEX) do not restore. The statistical survey of 84 isolated storms demonstrates that geomagnetic storms preferentially decrease relativistic electron fluxes at higher energies while flux enhancements are more common at lower energies: ~ 82% (3%) storm events produce increased (decreased) flux for 0.3-2.5 MeV electrons, while ~ 37% (45%) storms lead to enhancements (reductions) of 2.5-14 MeV electron flux. Superposed epoch analysis suggests that "energy dependent" events preferentially occur during periods of high solar wind density along with high dynamic pressure. Previous statistical studies have shown that this kind of solar wind conditions account for significant enhancements of EMIC waves, which cause efficient precipitation of > 2 MeV electrons into atmosphere via pitch angle scattering. Two cases of "energy dependent" events are investigated in detail with evident observations of EMIC waves that can resonate effectively with >2 MeV electrons. Besides, we do not capture much differences in the chorus wave activity between those "energy dependent" and "energy independent" events. Therefore, our results strongly suggest that EMIC waves play a crucial role in the occurrences of those "energy dependent" events in the outer zone during geomagnetic storms.

  9. An empirical model of the quiet daily geomagnetic field variation

    USGS Publications Warehouse

    Yamazaki, Y.; Yumoto, K.; Cardinal, M.G.; Fraser, B.J.; Hattori, P.; Kakinami, Y.; Liu, J.Y.; Lynn, K.J.W.; Marshall, R.; McNamara, D.; Nagatsuma, T.; Nikiforov, V.M.; Otadoy, R.E.; Ruhimat, M.; Shevtsov, B.M.; Shiokawa, K.; Abe, S.; Uozumi, T.; Yoshikawa, A.

    2011-01-01

    An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ??? 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit north-south asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity. Copyright 2011 by the American Geophysical Union.

  10. Role of centennial geomagnetic changes in local atmospheric ionization

    NASA Astrophysics Data System (ADS)

    Usoskin, I. G.; Korte, M.; Kovaltsov, G. A.

    2008-03-01

    Many studies of solar-terrestrial relation are based on globally (or hemispherically) averaged quantities, including the average cosmic ray flux. However, regional effects of cosmic ray induced ionization due to geomagnetic changes may be comparable to or even dominate over the solar signal at mid-latitudes on centennial-to-millennial time scales. We show that local changes of the tropospheric ionization due to fast migration of the geomagnetic axis are crucial on centennial time scale, and the use of global averages may smear an important effect. We conclude that changes of the regional tropospheric ionization at mid-latitudes are defined by both geomagnetic changes and solar activity, and none of the two processes can be neglected. This substantiates a necessity for a careful analysis of the regional, not global, indices at mid-latitudes and offers a new possibility to disentangle direct (solar radiation) and indirect (via cosmic rays) effects in the solar-terrestrial relations.

  11. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<−100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3–6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow. PMID:26167429

  12. Mantle superplumes induce geomagnetic superchrons

    NASA Astrophysics Data System (ADS)

    Olson, Peter; Amit, Hagay

    2015-07-01

    We use polarity reversal systematics from numerical dynamos to quantify the hypothesis that the modulation of geomagnetic reversal frequency, including geomagnetic superchrons, results from changes in core heat flux related to growth and collapse of lower mantle superplumes. We parameterize the reversal frequency sensitivity from numerical dynamos in terms of average core heat flux normalized by the difference between the present-day core heat flux and the core heat flux at geomagnetic superchron onset. A low-order polynomial fit to the 0-300 Ma Geomagnetic Polarity Time Scale (GPTS) reveals that a decrease in core heat flux relative to present-day of approximately 30% can account for the Cretaceous Normal Polarity and Kiaman Reverse Polarity Superchrons, whereas the hyper-reversing periods in the Jurassic require a core heat flux equal to or higher than present-day. Possible links between GPTS transitions, large igneous provinces (LIPs), and the two lower mantle superplumes are explored. Lower mantle superplume growth and collapse induce GPTS transitions by increasing and decreasing core heat flux, respectively. Age clusters of major LIPs postdate transitions from hyper-reversing to superchron geodynamo states by 30-60 Myr, suggesting that superchron onset may be contemporaneous with LIP-forming instabilities produced during collapses of lower mantle superplumes.

  13. Climate determinism or Geomagnetic determinism?

    NASA Astrophysics Data System (ADS)

    Gallet, Y.; Genevey, A.; Le Goff, M.; Fluteau, F.; Courtillot, V.

    2006-12-01

    A number of episodes of sharp geomagnetic field variations (in both intensity and direction), lasting on the order of a century, have been identified in archeomagnetic records from Western Eurasia and have been called "archeomagnetic jerks". These seem to correlate well with multi-decadal cooling episodes detected in the North Atlantic Ocean and Western Europe, suggesting a causal link between both phenomena. A possible mechanism could be a geomagnetic modulation of the cosmic ray flux that would control the nucleation rate of clouds. We wish to underline the remarkable coincidence between archeomagnetic jerks, cooling events in Western Europe and drought periods in tropical and sub-tropical regions of the northern hemisphere. The latter two can be interpreted in terms of global teleconnections among regional climates. It has been suggested that these climatic variations had caused major changes in the history of ancient civilizations, such as in Mesopotamia, which were critically dependent on water supply and particularly vulnerable to lower rainfall amounts. This is one of the foundations of "climate determinism". Our studies, which suggest a geomagnetic origin for at least some of the inferred climatic events, lead us to propose the idea of a "geomagnetic determinism" in the history of humanity.

  14. The effect of solar activity on ill and healthy people under conditions of neurous and emotional stresses

    NASA Astrophysics Data System (ADS)

    Zakharov, I. G.; Tyrnov, O. F.

    2001-01-01

    It is commonly agreed that solar activity has adverse effects first of all on enfeebled and ill organisms. In our study we have traced that under conditions of neurous and emotional stresses (at work, in the street, and in cars) the effect may be larger (˜ 30 %) for healthy people. Our calculations have been carried out applying the epoch-superposition method, spectrum and correlation analyses to daily data over a 1992 to 1994 period from three independent databases (Kharkiv City) on patients (adults and children) suffering from mental diseases and physical traumas. The effect is most marked during the recovery phase of geomagnetic storms and accompanied by the inhibition in the central nervous system.

  15. Geomagnetic field effect on cardiovascular regulation.

    PubMed

    Gmitrov, Juraj; Gmitrova, Anna

    2004-02-01

    The goal of the present research was try to explain the physiological mechanism for the influence of the geomagnetic field (GMF) disturbance, reflected by the indices of the geomagnetic activity (K, K(p), A(k), and A(p) indices), on cardiovascular regulation. One hundred forty three experimental runs (one daily) comprising 50 min hemodynamic monitoring sequences were carried out in rabbits sedated by pentobarbital infusion (5 mg/kg/h). We examined the arterial baroreflex effects on the short term blood pressure and heart rate (HR) variabilities reflected by the standard deviation (SD) of the average values of the mean femoral arterial blood pressure (MAP) and the HR. Baroreflex sensitivity (BRS) was estimated from blood pressure/HR response to intravenous (i.v.) bolus injections of vasoconstrictor (phenylephrine) and vasodilator (nitroprusside) drugs. We found a significant negative correlation of increasing GMF disturbance (K(p)) with BRS (P = 0.008), HR SD (P =0.022), and MAP SD (P = 0.002) signifying the involvement of the arterial baroreflex mechanism. The abrupt change in geomagnetic disturbance from low (K = 0) to high (K = 4-5) values was associated with a significant increase in MAP (83 +/- 5 vs. 99 +/- 5 mm Hg, P = 0.045) and myocardial oxygen consumption, measured by MAP and HR product (24100 +/- 1800 vs. 31000 +/- 2500 mm Hg. bpm, P = 0.034), comprising an additional cardiovascular risk. Most likely, GMF affects brainstem and higher neural cardiovascular regulatory centers modulating blood pressure and HR variabilities associated with the arterial baroreflex. PMID:14735558

  16. Different geomagnetic indices as an indicator for geo-effective solar storms and human physiological state

    NASA Astrophysics Data System (ADS)

    Dimitrova, Svetla

    2008-02-01

    A group of 86 healthy volunteers were examined on each working day during periods of high solar activity. Data about systolic and diastolic blood pressure, pulse pressure, heart rate and subjective psycho-physiological complaints were gathered. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters. The factors were as follows: (1) geomagnetic activity estimated by daily amplitude of H-component of the local geomagnetic field, Ap- and Dst-index; (2) gender; and (3) the presence of medication. Average values of systolic, diastolic blood pressure, pulse pressure and subjective complaints of the group were found to increase significantly with geomagnetic activity increment.

  17. Effect of geomagnetic disturbances on physiological parameters: An investigation on aviators

    NASA Astrophysics Data System (ADS)

    Papailiou, M.; Mavromichalaki, H.; Kudela, K.; Stetiarova, J.; Dimitrova, S.

    2011-11-01

    Over the last years the potential effect that the geomagnetic activity may have on human physiological parameters (such as heart rate, arterial diastolic and systolic pressure) is being widely investigated with irrefutable results. As it is suggested, human health can be affected by solar activity and related geophysical changes. In this study a group of 4018 Slovak aviators was examined from January 1, 1994 to December 31, 2002, covering periods with high solar and geomagnetic activity. Specifically, medical data of mean values of arterial diastolic and systolic blood pressure, which were registered during the medical examinations of the Slovak aviators, were related to daily variations of Dst and Ap geomagnetic indices. All subjects were men (from 18 to 60 years old) in good health. Statistical significance levels (p-values) of the effect of geomagnetic activity on the aforementioned parameters up to three days before and three days after the geomagnetic event were established using the statistical method ANalysis Of VAriance (ANOVA). Statistical analysis of the arterial blood pressure variations for different levels of geomagnetic activity revealed that geomagnetic changes are connected to variations of the human physiological parameters.

  18. (abstract) A Geomagnetic Contribution to Climate Change in this Century

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Ruzmaikin, A.; Lawrence, J.

    1996-01-01

    There is a myth that all solar effects can be parameterized by the sun spot number. This is not true. For example, the level of geomagnetic activity during this century was not proportional to the sunspot number. Instead there is a large systematic increase in geomagnetic activity, not reflected in the sunspot number. This increase occurred gradually over at least 60 years. The 11 year solar cycle variation was superimposed on this systematic increase. Here we show that this systematic increase in activity is well correlated to the simultaneous increase in terrestrial temperature that occurred during the first half of this century. We discuss these findings in terms of mechanisms by which geomagnetics can be coupled to climate. These mechanisms include possible changes in weather patterns and cloud cover due to increased cosmic ray fluxes, or to increased fluxes of high energy electrons. We suggest that this systematic increase in geomagnetic activity contributed (along with anthropogenic effects and possible changes in solar irradiance) to the changes in climate recorded during this period.

  19. Active spectral sensor evaluation under varying conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant stress has been estimated by spectral signature using both passive and active sensors. As optical sensors measure reflected light from a target, changes in illumination characteristics critically affect sensor response. Active sensors are of benefit in minimizing uncontrolled illumination effe...

  20. Testing for Links Between Geomagnetic Field Variability and Climate Change

    NASA Astrophysics Data System (ADS)

    Wetter, L.; Acton, G.; Hill, T.

    2006-12-01

    Although orbital forcing controls much of long-term climate change and increases in greenhouse gases are thought to be driving recent global warming, other factors may also play a significant role. Recent studies have hypothesized various forms of links between climate change and solar irradiance, solar activity, and cosmic ray flux. Because changes in geomagnetic field strength affect the cosmic ray flux, it is possible that changes in the geomagnetic field contribute to long- and short-term climate change. Alternatively, it has been hypothesized that geomagnetic field variability is influenced by climate change or solar activity. We test such claims through a paleomagnetic and stable isotope study of Ocean Drilling Program (ODP) sediment cores from the Blake Outer Ridge (BOR), western North Atlantic Ocean. The goal of the study is to create a continuous, high-resolution record of geomagnetic field variability with an accurate, astronomically tuned chronology. Sediment cored on the BOR in four holes at Site 1061 during ODP Leg 172 is being used for this investigation. The high sedimentation rate, averaging 22 cm/k.y. over the Brunhes, and the exceptional paleomagnetic properties of the area make Site 1061 an excellent candidate to test for links between short- term geomagnetic events and climate. The paleomagnetic record, originally constructed mainly from continuous split-core measurements, is being refined and rock magnetic analyses are being conducted on U- channel samples that span the Brunhes. We have also refined the between-hole correlation and constructed a more detailed composite stratigraphic section for Site 1061 in order to improve the continuity and relative chronology of the record and to confirm the existence of distinct geomagnetic excursions and other short-term events in multiple drill holes. Additionally, planktonic forams are being measured for δ18 O variations across, and extending to one meter beyond each observed excursion, allowing for

  1. Achievement of a short term three dimensional electron density mapping of the ionosphere in the European sector: Comparisons with the IRI model for quiet-moderate geomagnetic-ionospheric conditions

    NASA Astrophysics Data System (ADS)

    Pietrella, M.

    2016-10-01

    In this paper will be described the procedure followed for the achievement of a short term three dimensional (3-D) electron density mapping of the ionosphere in the European area. It consists of three main steps: (1) foF2 and M(3000)F2 short-term forecasts, (foF2STF) and (M3000F2STF), are calculated at 12 ionospheric observatories scattered in the European area; (2) the values of foF2STF and M3000F2STF on a grid of equi-spaced points, (foF2STF,GP) and (M3000F2STF,GP), are calculated by means of an appropriate interpolation algorithm by using the foF2STF and M3000F2STF data; (3) foF2STF,GP and M3000F2STF,GP data ingestion into the IRI model is employed to produce a short term 3-D electron density mapping (ST-3D-M) of the ionosphere. The electron density profiles provided by the ST-3D-M and IRI models, were compared with the electron density profiles autoscaled by the Automatic Real-Time Ionogram Scaler with True-height (ARTIST) system, which are here considered as the truth profiles. The results of these comparisons, shown for a certain number of epochs during quiet-moderate geomagnetic-ionospheric conditions, in the truth-sites of Athens (38○.0‧N, 23○.5‧E), Chilton (51○.5‧N, -0○.6‧W), Dourbes (50○.1‧ N, 4○.6‧E), Pruhonice (50○.0‧N, 14○.6‧E), Rome (41○.9‧N, 12○.5‧E), and Tortosa (40○.8‧N, 0○.5‧E), indicate that the ST-3D-M as forecasting tool can be considered generally reliable.

  2. Worldwide Geomagnetic Data Collection and Management

    NASA Astrophysics Data System (ADS)

    Mandea, Mioara; Papitashvili, Vladimir

    2009-11-01

    Geomagnetic data provided by different platforms piece together a global picture of Earth's magnetic field and its interaction with geospace. Furthermore, a great diversity of the geomagnetic field changes, from secular (over decades to centuries) to short time variations (down to minutes and seconds), can be detected only through continued observations. An international effort to watch and record geomagnetic changes first began in the 1830s with a network of scientific observers organized by Karl Friedrich Gauss in Germany, and this effort has continued since then. One of the most remarkable achievements in understanding the geomagnetic field morphology and time behavior was made possible by the International Geophysical Year (IGY), an exploration and research effort that lasted for 18 months, starting on 1 July 1957. The IGY encompassed 11 geoscience disciplines, including geomagnetism. The IGY has represented a giant step forward in the quality and quantity of worldwide geomagnetic measurements, as well as in the widespread interest in magnetic measurements. A half century of probing the geomagnetic field spatial and temporal variations has produced a number of outstanding results, and the interested reader can find recent reviews on various geomagnetic field topics (from measurements to modeling) in Encyclopedia of Geomagnetism and Paleomagnetism [Gubbins and Herrero-Bervera, 2007] or Treatise on Geophysics: Geomagnetism [Kono, 2007].

  3. Conditions for Apprentices' Learning Activities at Work

    ERIC Educational Resources Information Center

    Messmann, Gerhard; Mulder, Regina H.

    2015-01-01

    The aim of this study was to investigate how apprentices' learning activities at work can be fostered. This is a crucial issue as learning at work enhances apprentices' competence development and prepares them for professional development on the job. Therefore, we conducted a study with 70 apprentices in the German dual system and examined the…

  4. Geomagnetic excursions and climate change

    NASA Technical Reports Server (NTRS)

    Rampino, M. R.

    1983-01-01

    Rampino argues that although Kent (1982) demonstrated that the intensity of natural remanent magnetism (NRM) in deep-sea sediments is sensitive to changes in sediment type, and hence is not an accurate indicator of the true strength of the geomagnetic field, it does not offer an alternative explanation for the proposed connections between excursions, climate, and orbital parameters. Kent replies by illustrating some of the problems associated with geomagnetic excursions by considering the record of proposed excursions in a single critical core. The large departure from an axial dipole field direction seen in a part of the sample is probably due to a distorted record; the drawing and storage of the sample, which is described, could easily have led to disturbance and distortion of the record.

  5. Teaching Geomagnetism in High School

    NASA Astrophysics Data System (ADS)

    Stern, D. P.

    2001-05-01

    Many high school curricula include a one-year course in Earth Sciences, often in the 9th grade (essentially pre-algebra). That is a good time to teach about geomagnetism. Not only are dipole reversals and sea-floor magnetization central to this subject, but this is a good opportunity to introduce students to magnetism and its connection to electric currents. The story of Oersted and Faraday give a fascinating insight into the uneven path of scientific discovery, the magnetic compass and William Gilbert provide a view of the beginnings of the scientific revolution, and even basic concepts of dynamo theory and its connection to solar physics can be included. A resource including all the suitable material now exists on the world-wide web at http://www-spof.gsfc.nasa.gov/earthmag/demagint.htm (home page). A 1-month unit on geomagnetism will be outlined.

  6. Ice ages and geomagnetic reversals

    NASA Technical Reports Server (NTRS)

    Wu, Patrick

    1992-01-01

    There have been speculations on the relationship between climatic cooling and polarity reversals of the earth's magnetic field during the Pleistocene. Two of the common criticisms on this relationship have been the reality of these short duration geomagnetic events and the accuracy of their dates. Champion et al. (1988) have reviewed recent progress in this area. They identified a total of 10 short-duration polarity events in the last 1 Ma and 6 of these events have been found in volcanic rocks, which also have K-Ar dates. Supposing that the speculated relationship between climatic cooling and geomagnetic reversals actually exist, two mechanisms that assume climatic cooling causes short period magnetic reversals will be investigated. These two methods are core-mantle boundary topography and transfer of the rotational energy to the core.

  7. Global geomagnetic field mapping - from secular variation to geomagnetic excursions

    NASA Astrophysics Data System (ADS)

    Panovska, Sanja; Constable, Catherine

    2015-04-01

    The main source of the geomagnetic field is a self-sustaining dynamo produced by fluid motions in Earth's liquid outer core. We study the spatial and temporal changes in the internal magnetic field by mapping the time-varying geomagnetic field over the past 100 thousand years. This is accomplished using a new global data set of paleomagnetic records drawn from high accumulation rate sediments and from volcanic rocks spanning the past 100 thousand years (Late Pleistocene). Sediment data comprises 105 declination, 117 inclination and 150 relative paleointensity (RPI) records, mainly concentrated in northern mid-latitudes, although some are available in the southern hemisphere. Northern Atlantic and Western Pacific are regions with high concentrations of data. The number of available volcanic/archeomagnetic data is comparitively small on the global scale, especially in the Southern hemisphere. Temporal distributions show that the number of data increases toward more recent times with a good coverage for the past 50 ka. Laschamp excursion (41 ka BP) is well represented for both directional and intensity data. The significant increase in data compared to previous compilations results in an improvement over current geomagnetic field models covering these timescales. Robust aspects of individual sediment records are successfully captured by smoothing spline modeling allowing an estimate of random uncertainties present in the records. This reveals a wide range of fidelities across the sediment magnetic records. Median uncertainties are: 17° for declination (range, 1° to 113°), 6° for inclination (1° to 50°) and 0.4 for standardized relative paleointensity (0.02 to 1.4). The median temporal resolution of the records defined by the smoothing time is 400 years (range, 50 years to about 14 kyr). Using these data, a global, time-varying, geomagnetic field model is constructed covering the past 100 thousand years. The modeling directly uses relative forms of sediment

  8. Correlative comparison of geomagnetic storms and auroral substorms using geomagnetic indeces. Master's thesis

    SciTech Connect

    Cade, W.B.

    1993-06-01

    Partial contents include the following: (1) Geomagnetic storm and substorm processes; (2) Magnetospheric structure; (3) Substorm processes; (4) Data description; (5) Geomagnetic indices; and (6) Data period and data sets.

  9. Do geomagnetic storms change the behaviour of the stingless bee guiruçu ( Schwarziana quadripunctata)?

    NASA Astrophysics Data System (ADS)

    Esquivel, Darci M. S.; Wajnberg, E.; Do Nascimento, F. S.; Pinho, M. B.; de Barros, H. G. P. Lins; Eizemberg, R.

    2007-02-01

    Six behavioural experiments were carried out to investigate the magnetic field effects on the nest-exiting flight directions of the honeybee Schwarziana quadripunctata ( Meliponini). No significant differences resulted during six experiment days under varying geomagnetic field and the applied static inhomogeneous field (about ten times the geomagnetic field) conditions. A surprising statistically significant response was obtained on a unique magnetic storm day. The magnetic nanoparticles in these bees, revealed by ferromagnetic resonance, could be involved in the observed effect of the geomagnetic storm.

  10. The Geomagnetic Field During a Reversal

    NASA Technical Reports Server (NTRS)

    Heirtzler, James R.

    2003-01-01

    By modifying the IGRF it is possible to learn what may happen to the geomagnetic field during a geomagnetic reversal. If the entire IGRF reverses then the declination and inclination only reverse when the field strength is zero. If only the dipole component of the IGRF reverses a large geomagnetic field remains when the dipole component is zero and he direction of the field at the end of the reversal is not exactly reversed from the directions at the beginning of the reversal.

  11. The geomagnetic tail

    SciTech Connect

    Birn, J. )

    1991-01-01

    A review is presented of the plasma sheet and lobe regions of the magnetotail, focusing principally on large-scale processes or microprocesses with some large-scale effects. Consideration is given to quiet and average structures, not necessarily related to activity phases, with quasi-steady convection aspects, and with the characteristics of dynamic phases including acceleration mechanisms and single particle aspects. Attention is given to various activity models, average and quiet time properties, properties and effects of magnetospheric convection, dynamics of the magnetotail, and the near tail, substorm current wedge.

  12. Geomagnetic Field Reversals and Life on the Earth in Phanerozoic Time

    NASA Astrophysics Data System (ADS)

    Pechersky, D. M.

    2014-10-01

    Global paleomagnetic and biostratigraphic data are generalized. As a result it is found out that the direct connection between geomagnetic reversals, biozones and maxima of mass extinction of a biota is absent. At the same time it is noted close to a synchronous total picture of consistent changes of biozones and geomagnetic polarity. It is explained by the general source - the Earth's diurnal rotation. The reversal polarity of a geomagnetic field prevailed during the Phanerozoic that is agreed with the Earth's counterclockwise rotation. Change of polarity of a field, most likely, is connected with acceleration or deceleration of rotation speed of the internal core relative to the Earth's mantle. Lack of direct interrelation between changes in the biosphere and geomagnetic field indicate a lack of influence of a field on life evolution on Earth. It follows also from the fact that life on Earth developed from primitive unicellular forms to mammals and the man and diversity of biota was grew against a close condition of a geomagnetic field during ~2,5 billion years and irrespective of numerous geomagnetic reversals. Main conclusion: evolutionary development of life on Earth doesn't depend both on large changes of a geomagnetic field, and on the extreme catastrophic events conducting to mass extinction of a biota.

  13. Geomagnetically induced currents in the New Zealand power network

    NASA Astrophysics Data System (ADS)

    Marshall, R. A.; Dalzell, M.; Waters, C. L.; Goldthorpe, P.; Smith, E. A.

    2012-08-01

    Adverse space weather conditions have been shown to be directly responsible for faults within power networks at high latitudes. A number of studies have also shown space weather to impact power networks at lower latitudes, although most of these studies show increases in GIC activity within networks not directly related to hardware faults. This study examines a GIC event that occurred in New Zealand's South Island power network on 6th November 2001. A transformer failure that occurred during this day is shown to be associated with a change in the solar wind dynamic pressure of nearly 20 nPa. Measurements of GICs recorded on the neutral lines of transformers across the Transpower network during this event show good correlation with a GIC-index, a proxy for the geoelectric field that drives GIC. Comparison of this event with GIC activity observed in the Transpower network during large space weather storms such as the "2003 Halloween storm," suggests that solar wind shocks and associated geomagnetic sudden impulse (SI) events may be as hazardous to middle latitude power networks as GIC activity occurring during the main phase of large storms. Further, this study suggests that the latitudinal dependence of the impacts of SI events on power systems differs from that observed during large main phase storms. This study also highlights the importance of operating procedures for large space weather events, even at middle latitude locations.

  14. Detailed Analysis of Solar Data Related to Historical Extreme Geomagnetic Storms: 1868 - 2010

    NASA Astrophysics Data System (ADS)

    Lefèvre, Laure; Vennerstrøm, Susanne; Dumbović, Mateja; Vršnak, Bojan; Sudar, Davor; Arlt, Rainer; Clette, Frédéric; Crosby, Norma

    2016-05-01

    An analysis of historical Sun-Earth connection events in the context of the most extreme space weather events of the last ˜150 years is presented. To identify the key factors leading to these extreme events, a sample of the most important geomagnetic storms was selected based mainly on the well-known aa index and on geomagnetic parameters described in the accompanying paper (Vennerstrøm et al., Solar Phys. in this issue, 2016, hereafter Paper I). This part of the analysis focuses on associating and characterizing the active regions (sunspot groups) that are most likely linked to these major geomagnetic storms.

  15. Variation of tidal winds in the ionosphere inferred from geomagnetic SQ field

    NASA Technical Reports Server (NTRS)

    Takeda, M.; Araki, T.

    1985-01-01

    The geomagnetic Sq field is mainly generated by the dynamo action of tidal winds in the ionosphere, and therefore some information can be derived from the variation of the Sq field. The geomagnetic Sq field was analyzed during March 1 to 18, 1980, when the geomagnetic activity was exceptionally low, and the equivalent Sq currents calculated every 2 hours by using the spherical harmonics method. Then additional Sq currents were extracted by subtracting the currents averaged through all days in the period from the original currents at each UT. The change of the instantaneous Sq current system by the above-mentioned method is discussed.

  16. Cosmic rays flux and geomagnetic field variations at midlatitudes

    NASA Astrophysics Data System (ADS)

    Morozova, Anna; Ribeiro, Paulo; Tragaldabas Collaboration Team

    2014-05-01

    It is well known that the cosmic rays flux is modulated by the solar wind and the Earth's magnetic field. The Earth's magnetic field deflects charged particles in accordance with their momentum and the local field strength and direction. The geomagnetic cutoffs depend both on the internal and the external components of the geomagnetic field, therefore reflecting the geodynamo and the solar activity variations. A new generation, high performance, cosmic ray detector Tragaldabas was recently installed at the University of Santiago de Compostela (Spain). The detector has been acquiring test data since September 2013 with a rate of about 80 events/s over a solid angle of ~5 srad. around the vertical direction. To take full advantage of this new facility for the study of cosmic rays arriving to the Earth, an international collaboration has been organized, of about 20 researchers from 10 laboratories of 5 European countries. The Magnetic Observatory of Coimbra (Portugal) has been measuring the geomagnetic field components for almost 150 years since the first measurements in 1866. It is presently equipped with up-to-date instruments. Here we present a preliminary analysis of the global cosmic ray fluxes acquired by the new Tragaldabas detector in relation to the geomagnetic field variations measured by the Coimbra observatory. We also compare the data from the new cosmic rays detector with results obtained by the Castilla-La Mancha Neutron Monitor (CaLMa, Gadalajara, Spain) that is in operation since October 2011.

  17. Geomagnetic Storms and Acute Myocardial Infarctions Morbidity in Middle Latitudes

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.; Babayev, E. S.; Mustafa, F. R.; Stoilova, I.; Taseva, T.; Georgieva, K.

    2009-12-01

    Results of collaborative studies on revealing a possible relationship between solar activity (SA) and geomagnetic activity (GMA) and pre-hospital acute myocardial infarction (AMI) morbidity are presented. Studies were based on medical data from Bulgaria and Azerbaijan. Bulgarian data, covering the period from 01.12.1995 to 31.12.2004, concerned daily distribution of number of patients with AMI diagnose (in total 1192 cases) from Sofia Region on the day of admission at the hospital. Azerbaijani data contained 4479 pre-hospital AMI incidence cases for the period 01.01.2003-31.12.2005 and were collected from 21 emergency and first medical aid stations in Grand Baku Area (including Absheron Economical Region with several millions of inhabitants). Data were "cleaned" as much as possible from social and other factors and were subjected to medical and mathematical/statistical analysis. Medical analysis showed reliability of the used data. Method of ANalysis Of VAriance (ANOVA) was applied to check the significance of GMA intensity effect and the type of geomagnetic storms - those caused by magnetic clouds (MC) and by high speed solar wind streams (HSSWS) - on AMI incidences. Relevant correlation coefficients were calculated. Results were outlined for both considered data. Results obtained for the Sofia data showed statistically significant positive correlation between considered GMA indices and AMI occurrence. ANOVA revealed that AMI incidence number was significantly increased from the day before till the day after geomagnetic storms with different intensities. Geomagnetic storms caused by MC were related to significant increase of AMI number in comparison with the storms caused by HSSWS. There was a trend for such different effects even on -1st and +1st day for the period 1995-2004. Results obtained for the Baku data revealed trends similar to those obtained for Sofia data. AMI morbidity increment was observed on the days with higher GMA intensity and after these days

  18. Effects of substorm electrojet on declination along concurrent geomagnetic latitudes in the northern auroral zone

    NASA Astrophysics Data System (ADS)

    Edvardsen, Inge; Johnsen, Magnar G.; Løvhaug, Unni P.

    2016-10-01

    The geomagnetic field often experiences large fluctuations, especially at high latitudes in the auroral zones. We have found, using simulations, that there are significant differences in the substorm signature, in certain coordinate systems, as a function of longitude. This is confirmed by the analysis of real, measured data from comparable locations. Large geomagnetic fluctuations pose challenges for companies involved in resource exploitation since the Earth's magnetic field is used as the reference when navigating drilling equipment. It is widely known that geomagnetic activity increases with increasing latitude and that the largest fluctuations are caused by substorms. In the auroral zones, substorms are common phenomena, occurring almost every night. In principle, the magnitude of geomagnetic disturbances from two identical substorms along concurrent geomagnetic latitudes around the globe, at different local times, will be the same. However, the signature of a substorm will change as a function of geomagnetic longitude due to varying declination, dipole declination, and horizontal magnetic field along constant geomagnetic latitudes. To investigate and quantify this, we applied a simple substorm current wedge model in combination with a dipole representation of the Earth's magnetic field to simulate magnetic substorms of different morphologies and local times. The results of these simulations were compared to statistical data from observatories and are discussed in the context of resource exploitation in the Arctic. We also attempt to determine and quantify areas in the auroral zone where there is a potential for increased space weather challenges compared to other areas.

  19. Analysis of the Solar Diameter Variations at July, 1986 and the Geomagnetic Storm of March, 1989

    NASA Astrophysics Data System (ADS)

    Humberto Andrei, Alexandre; Garcia, Marcos A.; Papa, Andres R. R.; Calderari Boscardin, Sergio; Lousada Penna, Jucira; Sigismondi, Costantino

    2015-08-01

    In this work, we have a well-known event in scientific literature used to illustrate our investigation on the viability of the solar diameter variation be a precursor for the occurrence of sets of coronal mass ejections, and thus, for geomagnetic storms, as noted in previous works of our group, but now, in a time scale of a few days. The selected event was that of March 13, 1989, a strong geomagnetic storm that made the Hydro-Quebec power grid fall down by 9 hours, damaging the local economy in millions of dollars. At the same time we have investigated a time interval belonging to a solar minimum period, on July 1986, prior to the rising phase and solar maximum of Solar Cycle 22, to compare with the geomagnetic pattern, as well as with the solar diameter behavior along these periods of low solar and geomagnetic activity. We used the time series of the CERGA’s astrolabe (because its dataset is long enough as to comprise both time periods of the analysis), the geomagnetic index AP and the H geomagnetic component from the Tatuoca Magnetic Observatory (because it is near to the geomagnetic equator and with the extra aim of checking the sensitivity of its magnetometers to global events).

  20. Substorms observations over Apatity during geomagnetic storms in the period 2012 - 2016

    NASA Astrophysics Data System (ADS)

    Guineva, Veneta; Werner, Rolf; Despirak, Irina; Kozelov, Boris

    2016-07-01

    In this work we studied substorms, generated during enhanced geomagnetic activity in the period 2012 - 2016. Observations of the Multiscale Aurora Imaging Network (MAIN) in Apatity have been used. Solar wind and interplanetary magnetic field parameters were judged by the 1-min sampled OMNI data base. Substorm onset and further development were verified by the 10-s sampled data of IMAGE magnetometers and by data of the all-sky camera at Apatity. Subject of the study were substorms occurred during geomagnetic storms. The so-called "St. Patrick's day 2015 event" (17-21 March 2015), the events on 17-18 March 2013 and 7-17 March 2012 (a chain of events generated four consecutive storms) which were among the events of strongest geomagnetic activity during the current solar cycle 24, were part of the storms under consideration. The behavior of the substorms developed during different phases of the geomagnetic storms was discussed.

  1. The quasi-biennial variation in the geomagnetic field: a global characteristics analysis

    NASA Astrophysics Data System (ADS)

    Ou, Jiaming; Du, Aimin

    2016-04-01

    exhibits distinct anisotropic in the local time distribution. The QBO of the X and Z components are both stronger over LT 00:00-06:00. The results of spherical harmonic analysis indicate that the QBO is mainly contributed by the external sources. The QBO is highly correlated with various parameters of solar activity, solar wind at 1AU, and geomagnetic activity. Reference 1. Sugiura, M. (1976). Quasi-biennial geomagnetic variation caused by the Sun. Geophys. Res. Lett., 3(11), 643-646. 2. Silva, L., Jackson, L., and Mound, J., (2012), Assessing the importance and expression of the 6 year geomagnetic oscillation, J. Geophys. Res.: Solid Earth (1978-2012), 117.

  2. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W.; Taylor, E.R. Jr.; Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems` responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  3. Electric Utility Industry Experience with Geomagnetic Disturbances

    SciTech Connect

    Barnes, P.R.

    1991-01-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as a few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration.

  4. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. ); Taylor, E.R. Jr. ); Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  5. Geophysical excitation of nutation and geomagnetic jerks

    NASA Astrophysics Data System (ADS)

    Vondrák, Jan; Ron, Cyril

    2014-05-01

    Recently Zinovy Malkin (2013) proposed that the observed changes of Free Core Nutation parameters (phase, amplitude) might be related to geomagnetic jerks (rapid changes of the secular variations of geomagnetic field). We tested this hypothesis and found that if the numerical integration of Brzezinski broad-band Liouville equations of atmospheric/oceanic excitations is re-initialized at the epochs of geomagnetic jerks, the agreement between the integrated and observed celestial pole offsets is improved significantly. This approach however tacitly assumes that the influence of geomagnetic jerks has a stepwise character, which is physically not acceptable. The present study continues in this effort by introducing a simple continuous excitation function (hypothetically due to geomagnetic jerks). The results of numerical integration of atmospheric/oceanic excitations plus this newly introduced excitation are then compared with the observed celestial pole offsets.

  6. Solar, interplanetary and geomagnetic phenomena in March 1991 and their association with spacecraft and terrestrial problems

    SciTech Connect

    Smart, D.F.; Shea, M.A.; Fluekiger, E.O.; Sanahuja, B.

    1995-12-31

    The solar activity that occurred on 22 and 23 March 1991 resulted in major interplanetary and geomagnetic disturbances. In spite of measurements in the earth`s magnetosphere, near Venus, and by the Ulysses spacecraft (at 2.48 AU), it is not possible to identify unambiguously the source of each perturbation. A very powerful shock resulted in large geomagnetic disturbances and contributed to the generation of a third radiation belt, as measured by the CRRES spacecraft.

  7. Gravity wave activity in the thermosphere inferred from GOCE data, and its dependence on solar flux conditions.

    NASA Astrophysics Data System (ADS)

    Garcia, Raphael F.; Bruinsma, Sean; Doornbos, Eelco; Massarweh, Lotfi

    2016-04-01

    This study is focused on the effect of solar flux conditions on the dynamics of Gravity Waves (GW) in thermosphere. Air density and cross-wind in situ estimates from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) accelerometers are analyzed for the whole mission duration. The analysis was performed in the Fourier spectral domain averaging spectral results over periods of 2 months close to solstices. First the Amplitude Spectral Density (ASD) and the Magnitude Squared Coherence (MSC) of physical parameters are linked to local gravity waves. Then, a new GW marker (called Cf3) was introduced here to constrain GWs activity under Low, Medium and High solar flux conditions, showing a clear solar dumping effect on GW activity. Most of GW signal has been found in a spectral range above 8 mHz in GOCE data, meaning a maximum horizontal wavelength around 1000 km. The level GW activity at GOCE altitude is strongly decreasing with increasing solar flux. Furthermore, a shift in the dominant frequency with solar flux conditions has been noted, leading to a larger horizontal wavelengths (from 200 to 500 km) during high solar flux conditions. The influence of correlated error sources, between air density and cross-winds, is discussed. Consistency of the spectral domain results has been verified in time-domain with a global mapping of high frequency perturbations along GOCE orbit. This analysis shows a clear dependence with geomagnetic latitude with strong perturbations at magnetic poles, and an extension to lower latitudes favoured by low solar activity conditions. Various possible causes of this spatial trend are discussed.

  8. Alternating light-darkness-influenced human electrocardiographic magnetoreception in association with geomagnetic pulsations.

    PubMed

    Otsuka, K; Oinuma, S; Cornélissen, G; Weydahl, A; Ichimaru, Y; Kobayashi, M; Yano, S; Holmeslet, B; Hansen, T L; Mitsutake, G; Engebretson, M J; Schwartzkopff, O; Halberg, F

    2001-01-01

    December 10, 1998, and November 2, 2000, on 19 clinically healthy subjects, 21 to 54 years of age, in Alta, Norway. A geomagnetic record was obtained from the Auroral Observatory of the University of Tromsø. First, frequency-domain measures of HRV were compared for each person in 24-hour spans of high geomagnetic disturbance versus quiet conditions. Second, cross-spectra between geomagnetic activity and HRV measures were quantified via the squared coherence spectrum using 7-day time series. A 7.5% increase in the 24-hour average of heart rate, HR (P = 0.00020) and a decrease in HRV were documented on days of high geomagnetic disturbance. The decrease in HRV was validated statistically for the 'total frequency', 'TF' endpoint (18.6% decrease, P= 0.00009). The decrease in spectral power was found primarily in the 'circaminutan frequency', 'VLF' (21.9% decrease, P< 0.000001) in conjunction with the 'minutes-to-hours' component, ultra-low-frequency, 'ULF' (15.5% decrease, P= 0.00865) and circadecasecundan 'low frequency', 'LF' (14.2% decrease, P = 0.00187) regions of the spectrum. Power-law scaling of the power spectra did not show any statistically significant difference. It is noteworthy that most of the decrease in HRV, except for the circaminutan (VLF) component, was observed only in the season in which sunshine alternated with darkness (D/L), a finding suggesting a mechanism influenced by the alternation of light and darkness. The hypothesis of a light-dark-influenced magnetoreception was also supported by cross-spectral analysis. Group-averaged coherence at frequencies coincident with the geomagnetic Pc 6 pulsations (with periods ranging from 10 minutes to 5 hours) differed with a statistical significance (P < 0.000001) among the three natural lighting conditions, the association being weaker during UL or D/D than during D/L. By contrast, no statistically significant differences were found in terms of the circadian and circasemidian frequencies in relation to the

  9. History of the geomagnetic field

    USGS Publications Warehouse

    Doell, Richard R.

    1969-01-01

    Direct measurements of the direction and strength of the earth's magnetic field have provided a knowledge of the field's form and behavior during the last few hundreds of years. For older times, however, it has been necessary to measure the magnetism of certain rocks to learn what the geomagnetic field was like. For example, when a lava flow solidifies (at temperatures near 1000??C) and cools through the Curie point of the magnetic minerals contained in it (around 500??C) it acquires a remanent magnetism that is (1) very weak, (2) very stablel, (3) paralle to the direction of the ambient geomagnetic field, and (4) proportional in intensity to the ambient field. Separating, by various analytical means, this magnetization from other 'unwanted' magnetizations has allowed paleomagnetists to study the historical and prehistorical behavior of the earth's field. It has been learned, for example, that the strength of the field was almost twice its present value 2000 years ago and that it has often completely reversed its polarity. Paleo-magnetists have also confirmed that most oceans are, geologically speaking, relatively new features, and that the continents have markedly changed their positions over the surface of the earth. ?? 1969 The American Institute of Physics.

  10. Probing geomagnetic storm-driven magnetosphere-ionosphere dynamics in D-region via propagation characteristics of very low frequency radio signals

    NASA Astrophysics Data System (ADS)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip K.; Ogunmodimu, Olugbenga

    2016-07-01

    The amplitude and phase of VLF/LF radio signals are sensitive to changes in electrical conductivity of the lower ionosphere which imprints its signature on the Earth-ionosphere waveguide. This characteristic makes it useful in studying sudden ionospheric disturbances, especially those related to prompt X-ray flux output from solar flares and gamma ray bursts (GRBs). However, strong geomagnetic disturbance and storm conditions are known to produce large and global ionospheric disturbances, which can significantly affect VLF radio propagation in the D region of the ionosphere. In this paper, using the data of three propagation paths at mid-latitudes (40-54°), we analyse the trend in variation of aspects of VLF diurnal signal under varying solar and geomagnetic space environmental conditions in order to identify possible geomagnetic footprints on the D region characteristics. We found that the trend of variations generally reflected the prevailing space weather conditions in various time scales. In particular, the 'dipping' of mid-day signal amplitude peak (MDP) occurs after significant geomagnetic perturbed or storm conditions in the time scale of 1-2 days. The mean signal amplitude before sunrise (MBSR) and mean signal amplitude after sunset (MASS) also exhibit storm-induced dipping, but they appear to be influenced by event's exact occurrence time and the highly variable conditions of dusk-to-dawn ionosphere. We also observed few cases of the signals rise (e.g., MDP, MBSR or MASS) following a significant geomagnetic event. This effect may be related to storms associated phenomena or effects arising from sources other than solar origin. The magnitude of induced dipping (or rise) significantly depends on the intensity and duration of event(s), as well as the propagation path of the signal. The post-storm day signal (following a main event, with lesser or significantly reduced geomagnetic activity) exhibited a tendency of recovery to pre-storm day level. In the

  11. Reduction of the field-aligned potential drop in the polar cap during large geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Kitamura, N.; Seki, K.; Nishimura, Y.; Hori, T.; Terada, N.; Ono, T.; Strangeway, R. J.

    2013-12-01

    We have studied photoelectron flows and the inferred field-aligned potential drop in the polar cap during 5 large geomagnetic storms that occurred in the periods when the photoelectron observations in the polar cap were available near the apogee of the FAST satellite (~4000 km) at solar maximum, and the footprint of the satellite paths in the polar cap was under sunlit conditions most of the time. In contrast to the ~20 V potential drop during geomagnetically quiet periods at solar maximum identified by Kitamura et al. [JGR, 2012], the field-aligned potential drop frequently became smaller than ~5 V during the main and early recovery phases of the large geomagnetic storms. Because the potential acts to inhibit photoelectron escape, this result indicates that the corresponding acceleration of ions by the field-aligned potential drop in the polar cap and the lobe region is smaller during the main and early recovery phases of large geomagnetic storms compared to during geomagnetically quiet periods. Under small field-aligned current conditions, the number flux of outflowing ions should be nearly equal to the net escaping electron number flux. Since ions with large flux originating from the cusp/cleft ionosphere convect into the polar cap during geomagnetic storms [e.g., Kitamura et al., JGR, 2010], the net escaping electron number flux should increase to balance the enhanced ion outflows. The magnitude of the field-aligned potential drop would be reduced to let a larger fraction of photoelectrons escape.

  12. Long-term biases in geomagnetic K and aa indices

    USGS Publications Warehouse

    Love, J.J.

    2011-01-01

    Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0-2009.0, solar cycles 11-23. The K data show persistent biases, especially for high (low) K-activity levels at British (Australian) observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4. ?? 2011 Author(s).

  13. Interplanetary coronal mass ejections and their geomagnetic consequences during solar cycle 24

    NASA Astrophysics Data System (ADS)

    Maris Muntean, Georgeta; Mierla, Marilena; Besliu-Ionescu, Diana; Lacatus, Dana; Razvan Paraschiv, Alin

    Geomagnetic storms are known to be of great importance to life on Earth through their impact on telecommunications, electric power networks and much more. Our study will analyse in detail two months of solar and geomagnetic activity in March 2012 and, March 2013. There is an ICME (Interplanetary Coronal Mass Ejection) recorded on March 9, 2012 listed in the Richardson and Cane catalogue, correlated with a Halo CME (Coronal Mass Ejection) from March 7. An intense geomagnetic storm (minimum Dst = -131 nT) was registered on March 9, 2012. Out of the two ICMEs recorded on the 17th and 20th March 2013, only the first was clearly associated with a Halo CME from March, 15. March, 17 is a day of intense geomagnetic storm (minimum Dst = -132 nT). We will focus on these events, such that the interaction between ICMEs and interplanetary magnetic field from the Sun to the Earth can be thoroughly described.

  14. The role of SANSA's geomagnetic observation network in space weather monitoring: A review

    NASA Astrophysics Data System (ADS)

    Kotzé, P. B.; Cilliers, P. J.; Sutcliffe, P. R.

    2015-10-01

    Geomagnetic observations play a crucial role in the monitoring of space weather events. In a modern society relying on the efficient functioning of its technology network such observations are important in order to determine the potential hazard for activities and infrastructure. Until recently, it was the perception that geomagnetic storms had no or very little adverse effect on radio communication and electric power infrastructure at middle- and low-latitude regions like southern Africa. The 2003 Halloween storm changed this perception. In this paper we discuss the role of the geomagnetic observation network operated by the South African National Space Agency (SANSA) in space weather monitoring. The primary objective is to describe the geomagnetic data sets available to characterize and monitor the various types of solar-driven disturbances, with the aim to better understand the physics of these processes in the near-Earth space environment and to provide relevant space weather monitoring and prediction.

  15. A Spectrophotometric Assay Optimizing Conditions for Pepsin Activity.

    ERIC Educational Resources Information Center

    Harding, Ethelynda E.; Kimsey, R. Scott

    1998-01-01

    Describes a laboratory protocol optimizing the conditions for the assay of pepsin activity using the Coomasie Blue dye binding assay of protein concentration. The dye bonds through strong, noncovalent interactions to basic and aromatic amino acid residues. (DDR)

  16. Ezekiel's vision: Visual evidence of Sterno-Etrussia geomagnetic excursion?

    NASA Astrophysics Data System (ADS)

    Raspopov, Oleg M.; Dergachev, Valentin A.; Goos'kova, Elena G.

    In the Eos article,“Ezekiel and the Northern Lights: Biblical Aurora Seems Plausible” (16 April 2002), Siscoe et al. presented arguments showing that coronal auroras can occur at low latitudes under the condition of increased geomagnetic dipole field strength. From this standpoint, they give an interpretation of the “reported” Ezekiel's vision (the Bible's Book of Ezekiel in the Old Testament). The site of the Ezekiel's vision was about 100 km south of Babylon (latitude ˜32° N, longitude ˜5°E), and the date of the vision was around 593 B.C. Auroral specialists believe that Ezekiel's vision was inspired by a very strong magnetic storm accompanied by coronal auroras at low latitudes. However, as justly noted by Siscoe et al. [2002],to adopt this interpretation, several questions should be answered. Can auroras be seen at the latitude where Ezekiel reportedly was? More important, can they reach a coronal stage of development, which is what the vision requires? Was the tilt of the dipole axis favorable? Was the general level of solar activity favorable? The principal question is, no doubt, the second one.

  17. Solar and Interplanetary Disturbances Causing Moderate Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Pratap Yadav, Mahendra; Kumar, Santosh

    2003-07-01

    The effect of solar and interplanetary disturbances on geomagnetospheric conditions leading to one hundred twenty one moderate geomagnetic storms (MGSs) with planetary index, Ap ≥ 20 and horizontal component of earth's magnetic field, H ≤ 250γ have been investigated using solar geophysical data (SGD), solar wind plasma (SWP) and interplanetary magnetic field (IMF) data during the period 1978-99. It is observed statistically that 64%, 36%, MGSs have occurred during maximum and minimum phase of solar cycle 21st and 22nd respectively. Further, it is observed that Hα, X-ray solar flares and active prominences and disapp earing filaments (APDFs) have occurred within lower helio latitude region associated with larger number of MGSs. No significant correlation between the intensity of GMSs and importance of Hα, X-ray solar flares have been observed. Maximum number of MGSs are associated with solar flares of lower importance of solar flare faint (SF). The lower importance in association with some specific characteristics i.e. location, region, duration of occurrence of event may also cause MGSs. The correlation coefficient between MGSs and sunspot numbers (SSNs) using Karl Pearson method, has been obtained 0.37 during 1978-99.

  18. Latitudinal electron precipitation patterns during large and small IMF magnitudes for northward IMF conditions

    NASA Technical Reports Server (NTRS)

    Makita, K.; Meng, C.-I.; Akasofu, S.-I.

    1988-01-01

    It is demonstrated that there are distinct differences in the electron precipitation patterns (or the polar cap size), geomagnetic activity, and field-aligned currents in the highest-latitude region for small and large IMF B(z) values when the IMF B(z) component is positive. First, during periods of weakly northward IMF, there is a distinct area in the highest-latitude region in which the electron precipitation is absent except for the polar rain. By contrast, during strongly northward IMF, the entire polar region is often filled with burst-type soft electron precipitations. Second, geomagnetic disturbances and field-aligned-current intensities in the highest-latitude region are less during a weak IMF B(z) condition than those during a strongly northward IMF B(z) condition. Geomagnetic activity in the auroral zone for both conditions is absent or very weak.

  19. Solar and geomagnetic trends of equatorial evening and nighttime F region vertical ion drifts

    NASA Astrophysics Data System (ADS)

    Oyekola, O. S.; Oluwafemi, C. O.

    2008-12-01

    F region vertical ion drifts were inferred from the evening and nighttime ionosonde data for two magnetic equatorial stations in West Africa: Ouagadougou (geographic: 12°N, 1.5°W; 5.9°N dip) and Ibadan (geographic: 7.9°N, 3.9°E; 6°S dip). We examine and discuss the short-term patterns of behavior of ionospheric variability over Ouagadougou for 1986-1987 years of low solar activity (F10.7 = 80) and 1988-1989 years of high solar activity (F10.7 = 180) for quiet time, while that of Ibadan is for undisturbed (Kp ≤ 3.0) and disturbed (Kp > 3.0) geomagnetic conditions during the 1958 International Geophysical Year (IGY) period, corresponding to high solar flux conditions (F10.7 = 208). Our results indicate that the evening and nighttime ion drift exhibits strong variations with the phase of the solar cycle but only small variations with geomagnetic activity. The characteristic values of evening prereversal velocity enhancements (PRE) vary between about 2-14 m/s and 12-22 m/s and 17-42 m/s and 18-40 m/s for low and high solar flux, unperturbed and perturbed conditions, in that order. The solar minimum evening reversal times are strongly season dependent, while the morning reversal times are season independent except during December solstice, which occurs earliest. During solar maximum, reversal times near dawn and dusk are essentially season independent except during June solstice season, which occurs late. The average occurrence time (1900 LT) of PRE is strongly independent of solar and magnetic variations apart from June solstice of high solar activity periods.

  20. What are the evidences of solar activity influence on coronary heart disease?

    NASA Astrophysics Data System (ADS)

    Gurfinkel, Yury; Breus, Tamara

    Researches of last two decades have shown that the cardiovascular system represents the most probable target for influence of helio - and geomagnetic activity. Both cardiovascular system and blood connect very closely: one system cannot exist without another. For the same reason the effects perceived by one system, are easily transferred to another. Laboratory tests as blood coagulation, platelet aggregation, and capillary blood velocity performed in our hospital in patients suffering from coronary heart disease (CHD) revealed a high their dependence on a level of geomagnetic activity (Gurfinkel et al., 1995, 1998). Later Gmitrov and Ohkubo (2002) in experiments on animals also found a significant negative correlation between geomagnetic field disturbances and capillary blood velocity. The analyzing data collected by the Moscow ambulance services covering more then one million observations over three years, cleaned up by seasonal effects of meteorological and social causes, showed that the number of cases of myocardial infarction increased during geomagnetic storms (Breus et al., 1995). During 14 years we collected more than 25000 cases of acute myocardial infarction and brain stroke at seven medical hospitals located in Russia, China and some other countries. We used only cases with established date of acute attack of diseases. Undated cases were excluded from the analysis. Average numbers of patients on geomagnetic active days and days with quiet geomagnetic condition were compared. It was shown statistically that during geomagnetic disturbances the frequency of myocardial infarction and brain stroke cases increased on the average by a factor of two in comparison with quiet geomagnetic conditions. These results are close to results obtained by (Stoupel, 1999), for patients suffering with acute cardiological pathology. Our recent study (with L.Parfeonova) revealed the relation between heart ventricular ectopic activity (VEA) and geomagnetic conditions in patients

  1. Space Weather Monitoring for ISS Geomagnetic Storm Studies

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Parker, Linda Neergaard

    2013-01-01

    The International Space Station (ISS) space environments community utilizes near real time space weather data to support a variety of ISS engineering and science activities. The team has operated the Floating Potential Measurement Unit (FPMU) suite of plasma instruments (two Langmuir probes, a floating potential probe, and a plasma impedance probe) on ISS since 2006 to obtain in-situ measurements of plasma density and temperature along the ISS orbit and variations in ISS frame potential due to electrostatic current collection from the plasma environment (spacecraft charging) and inductive (vxB) effects from the vehicle motion across the Earth s magnetic field. An ongoing effort is to use FPMU for measuring the ionospheric response to geomagnetic storms at ISS altitudes and investigate auroral charging of the vehicle as it passes through regions of precipitating auroral electrons. This work is challenged by restrictions on FPMU operations that limit observation time to less than about a third of a year. As a result, FPMU campaigns ranging in length from a few days to a few weeks are typically scheduled weeks in advance for ISS engineering and payload science activities. In order to capture geomagnetic storm data under these terms, we monitor near real time space weather data from NASA, NOAA, and ESA sources to determine solar wind disturbance arrival times at Earth likely to be geoeffective (including coronal mass ejections and high speed streams associated with coronal holes) and activate the FPMU ahead of the storm onset. Using this technique we have successfully captured FPMU data during a number of geomagnetic storm periods including periods with ISS auroral charging. This presentation will describe the strategies and challenges in capturing FPMU data during geomagnetic storms, the near real time space weather resources utilized for monitoring the space weather environment, and provide examples of auroral charging data obtained during storm operations.

  2. Multiscale Features of Large Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    De Michelis, P.; Consolini, G.

    2011-12-01

    The present study is focused on the analysis of the multiscale features of four large geomagnetic storms that occurred from 2000 to 2003. In particular, we analyse the fluctuations of these extreme events as recorded along the horizontal component of the geomagnetic field in seven different canadian geomagnetic observatories, by decomposing the signal via the Hilbert-Huang transform (HHT). This empirical method, that is alternative to traditional data-analysis methods, consists in an empirical mode decomposition (EMD) and in the Hilbert spectral analysis, and it is designed specifically for analyzing nonlinear and nonstationary data. The features of the intrinsic mode functions (IMFs) are studied as a function of the magnetic latitude.

  3. Changes in complex spike activity during classical conditioning

    PubMed Central

    Rasmussen, Anders; Jirenhed, Dan-Anders; Wetmore, Daniel Z.; Hesslow, Germund

    2014-01-01

    The cerebellar cortex is necessary for adaptively timed conditioned responses (CRs) in eyeblink conditioning. During conditioning, Purkinje cells acquire pause responses or “Purkinje cell CRs” to the conditioned stimuli (CS), resulting in disinhibition of the cerebellar nuclei (CN), allowing them to activate motor nuclei that control eyeblinks. This disinhibition also causes inhibition of the inferior olive (IO), via the nucleo-olivary pathway (N-O). Activation of the IO, which relays the unconditional stimulus (US) to the cortex, elicits characteristic complex spikes in Purkinje cells. Although Purkinje cell activity, as well as stimulation of the CN, is known to influence IO activity, much remains to be learned about the way that learned changes in simple spike firing affects the IO. In the present study, we analyzed changes in simple and complex spike firing, in extracellular Purkinje cell records, from the C3 zone, in decerebrate ferrets undergoing training in a conditioning paradigm. In agreement with the N-O feedback hypothesis, acquisition resulted in a gradual decrease in complex spike activity during the conditioned stimulus, with a delay that is consistent with the long N-O latency. Also supporting the feedback hypothesis, training with a short interstimulus interval (ISI), which does not lead to acquisition of a Purkinje cell CR, did not cause a suppression of complex spike activity. In contrast, observations that extinction did not lead to a recovery in complex spike activity and the irregular patterns of simple and complex spike activity after the conditioned stimulus are less conclusive. PMID:25140129

  4. Minimax confidence intervals in geomagnetism

    NASA Technical Reports Server (NTRS)

    Stark, Philip B.

    1992-01-01

    The present paper uses theory of Donoho (1989) to find lower bounds on the lengths of optimally short fixed-length confidence intervals (minimax confidence intervals) for Gauss coefficients of the field of degree 1-12 using the heat flow constraint. The bounds on optimal minimax intervals are about 40 percent shorter than Backus' intervals: no procedure for producing fixed-length confidence intervals, linear or nonlinear, can give intervals shorter than about 60 percent the length of Backus' in this problem. While both methods rigorously account for the fact that core field models are infinite-dimensional, the application of the techniques to the geomagnetic problem involves approximations and counterfactual assumptions about the data errors, and so these results are likely to be extremely optimistic estimates of the actual uncertainty in Gauss coefficients.

  5. Frequency of Proterozoic geomagnetic superchrons

    NASA Astrophysics Data System (ADS)

    Driscoll, Peter E.; Evans, David A. D.

    2016-03-01

    Long-term geodynamo evolution is expected to respond to inner core growth and changing patterns of mantle convection. Three geomagnetic superchrons, during which Earth's magnetic field maintained a near-constant polarity state through tens of Myr, are known from the bio/magnetostratigraphic record of Phanerozoic time, perhaps timed according to supercontinental episodicity. Some geodynamo simulations incorporating a much smaller inner core, as would have characterized Proterozoic time, produce field reversals at a much lower rate. Here we compile polarity ratios of site means within a quality-filtered global Proterozoic paleomagnetic database, according to recent plate kinematic models. Various smoothing parameters, optimized to successfully identify the known Phanerozoic superchrons, indicate 3-10 possible Proterozoic superchrons during the 1300 Myr interval studied. Proterozoic geodynamo evolution thus appears to indicate a relatively narrow range of reversal behavior through the last two billion years, implying either remarkable stability of core dynamics over this time or insensitivity of reversal rate to core evolution.

  6. Teacher Mentoring: An Analysis of Roles, Activities, and Conditions.

    ERIC Educational Resources Information Center

    Wildman, Terry M.; And Others

    1992-01-01

    Mentors' notes and comments were analyzed to determine their perceptions of roles, activities, and conditions influencing their work with beginning teachers. Mentors had many helping strategies that developed and shaped complex roles. A conceptual framework of eight categories of mentoring activities addressing five domains of beginning teachers'…

  7. Deadlift muscle force and activation under stable and unstable conditions.

    PubMed

    Chulvi-Medrano, Iván; García-Massó, Xavier; Colado, Juan C; Pablos, Carlos; de Moraes, Joao Alves; Fuster, Maria A

    2010-10-01

    The objective of this study was to compare the production of force and paraspinal muscle activity between deadlifts carried out in a standard way and with different instability devices (Bosu and T-Bow). Deadlifts involve the performance of muscle activities with dynamic and isometric characteristics. Thirty-one subjects participated voluntarily in the study. Initially, they performed an isometric test for 5 seconds in each condition. After that, they performed a set of 5 repetitions with 70% of the maximum isometric force obtained in each one of the previously evaluated conditions. During the isometric tests, records of electromyographic activity and force production were obtained, whereas during the dynamic tests, only the electromyographic activity was registered. The subjects produced more force and muscle activity on the stable surface than under the other conditions during the isometric test (p < 0.05), and the same differences in muscle activity were observed during the dynamic test (p < 0.05). These data show that the performance of deadlifts under stable conditions favors a higher production of maximum strength and muscle activity. Therefore, we conclude that the use of instability devices in deadlift training does not increase performance, nor does it provide greater activation of the paraspinal muscles, leading us to question their value in the performance of other types of exercises. PMID:20885194

  8. Deciphering records of geomagnetic reversals

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Fournier, Alexandre

    2016-06-01

    Polarity reversals of the geomagnetic field are a major feature of the Earth's dynamo. Questions remain regarding the dynamical processes that give rise to reversals and the properties of the geomagnetic field during a polarity transition. A large number of paleomagnetic reversal records have been acquired during the past 50 years in order to better constrain the structure and geometry of the transitional field. In addition, over the past two decades, numerical dynamo simulations have also provided insights into the reversal mechanism. Yet despite the large paleomagnetic database, controversial interpretations of records of the transitional field persist; they result from two characteristics inherent to all reversals, both of which are detrimental to an ambiguous analysis. On the one hand, the reversal process is rapid and requires adequate temporal resolution. On the other hand, weak field intensities during a reversal can affect the fidelity of magnetic recording in sedimentary records. This paper is aimed at reviewing critically the main reversal features derived from paleomagnetic records and at analyzing some of these features in light of numerical simulations. We discuss in detail the fidelity of the signal extracted from paleomagnetic records and pay special attention to their resolution with respect to the timing and mechanisms involved in the magnetization process. Records from marine sediments dominate the database. They give rise to transitional field models that often lead to overinterpret the data. Consequently, we attempt to separate robust results (and their subsequent interpretations) from those that do not stand on a strong observational footing. Finally, we discuss new avenues that should favor progress to better characterize and understand transitional field behavior.

  9. Acceleration and loss of relativistic electrons during small geomagnetic storms

    SciTech Connect

    Anderson, B. R.; Millan, R. M.; Reeves, G. D.; Friedel, R. H. W.

    2015-12-02

    We report that past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms (Dst >₋50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result in flux depletion than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. Small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.

  10. Study of Tatun Volcanoes by Fluxgate Geomagnetic Data

    NASA Astrophysics Data System (ADS)

    Yang, D.; Yen, H. Y.; Chen, C. H.

    2014-12-01

    Tatun volcanoes, located at northern Taipei city, the capital city of Taiwan, are still active according to the previous studies. Thus, construct the geometry of the volcanic structures of Tatun volcanoes is necessary. We used 3-component geomagnetic data from two temporal fluxgate magnetometers and YMM(Yangming mountain) a permanent station from April to August 2014. The susceptibility of igneous rock is generally larger than metamorphic and sedimentary rocks, thus we use the Parkinson vectors derived from 3-component geomagnetic data through the magnetic transfer function to find out the location and geometry of the igneous rock under Tatun volcanoes. In order to know the depth of the anomalies, we used the magnetotelluric data of previous study that are in the vicinity of three stations to compute the skin depth, which show the relationship between frequency and the penetration depth of the electromagnetic wave. Then, we use the magnetic transfer function to calculate the azimuth of the anomalies at a specific depth.

  11. Acceleration and loss of relativistic electrons during small geomagnetic storms

    DOE PAGES

    Anderson, Brett R.; Millan, R. M.; Reeves, Geoffrey D.; Friedel, Reinhard Hans W.

    2015-12-02

    Past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms (Dst > –50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result in flux depletionmore » than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. As a result, small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.« less

  12. Acceleration and loss of relativistic electrons during small geomagnetic storms

    SciTech Connect

    Anderson, Brett R.; Millan, R. M.; Reeves, Geoffrey D.; Friedel, Reinhard Hans W.

    2015-12-02

    Past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms (Dst > –50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result in flux depletion than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. As a result, small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.

  13. Acceleration and loss of relativistic electrons during small geomagnetic storms

    DOE PAGES

    Anderson, B. R.; Millan, R. M.; Reeves, G. D.; Friedel, R. H. W.

    2015-12-02

    We report that past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms (Dst >₋50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result inmore » flux depletion than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. Small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.« less

  14. The response of mesospheric NO to geomagnetic forcing in 2002-2012 as seen by SCIAMACHY

    NASA Astrophysics Data System (ADS)

    Sinnhuber, M.; Friederich, F.; Bender, S.; Burrows, J. P.

    2016-04-01

    Daily NO number density, retrieved from measurements of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) from 2002 to 2012 for polar summer in the mesosphere, is used to investigate the response of NO to geomagnetic activity, as expressed by the auroral electrojet (AE) index. Applying the superposed epoch analysis, we observe a clear response of NO to strong geomagnetic forcing at geomagnetic latitudes 55-75°N/S and altitudes above 66 km. The 27 day solar rotation cycle is observed, indicating that some of the observed geomagnetic events are related to solar coronal holes. We find a linear relationship between anomalies of AE and NO at geomagnetic latitudes 55-70°N/S and 70-74 km altitude. A clear auroral oval-like structure is observed on days of strong geomagnetic forcing in both hemispheres, with small longitudinal inhomogeneities, which might be related to the South Atlantic Anomaly or the magnetic local time. The NO lifetime and production rate per AE anomaly has been derived from a least squares fit to the observations. Comparisons of results from a simple model using this empirical NO production and a lifetime varying from 1.2 days in summer to 10 days in winter to SCIAMACHY observations show good agreement. In particular, the strength and interannual variability of the wintertime maximum is well captured. This suggests that direct production of NO in the upper mesosphere above 72 km contributes substantially to the so-called energetic particle precipitation indirect effect.

  15. [ON HUMAN BODY REACTION TO A CHANGED GEOMAGNETIC BACKGROUND].

    PubMed

    Sterlikova, I V

    2015-01-01

    Purpose of the work was to test the concept about existence of a heliobiological relation in the Earth's middle-latitude region for which to analyze, as an example, frequency of circulatory disease exacerbation, mental and behavior disorders, and respiratory diseases (bronchial asthma). The subject and object of the experimental statistic survey have been dwellers of city of Murom (Vladimir region) located in middle-latitude geomagnetic region Φ ≈ 53 degrees. The source material in the investigation was medical data of the Murom ambulance service and geophysical data of the Borok geomagnetic observatory (Yaroslavl region). The survey went on 3 years from February, 1985 till December, 1987 and coincided with the rise of the 11th solar cycle. The largest number of calls to the ambulance service due to acute circulatory condition, mental or behavior disorders, respiratory diseases (bronchial asthma particularly) and their fatal outcome fell on periods of long absence of high-frequency geomagnetic pulsation within the frequency range of human biorhythms.

  16. [ON HUMAN BODY REACTION TO A CHANGED GEOMAGNETIC BACKGROUND].

    PubMed

    Sterlikova, I V

    2015-01-01

    Purpose of the work was to test the concept about existence of a heliobiological relation in the Earth's middle-latitude region for which to analyze, as an example, frequency of circulatory disease exacerbation, mental and behavior disorders, and respiratory diseases (bronchial asthma). The subject and object of the experimental statistic survey have been dwellers of city of Murom (Vladimir region) located in middle-latitude geomagnetic region Φ ≈ 53 degrees. The source material in the investigation was medical data of the Murom ambulance service and geophysical data of the Borok geomagnetic observatory (Yaroslavl region). The survey went on 3 years from February, 1985 till December, 1987 and coincided with the rise of the 11th solar cycle. The largest number of calls to the ambulance service due to acute circulatory condition, mental or behavior disorders, respiratory diseases (bronchial asthma particularly) and their fatal outcome fell on periods of long absence of high-frequency geomagnetic pulsation within the frequency range of human biorhythms. PMID:26554135

  17. Solar-Terrestrial Relations and Geomagnetic Variations

    NASA Astrophysics Data System (ADS)

    Ogunade, S. O.

    1995-01-01

    An overview of the solar environment and terrestrial magnetism is presented. The interactions of the solar environment and terrestrial magnetism are then discussed as they result in the creation of the magnetosphere and ionosphere with their corresponding current systems. Geomagnetic variations resulting from these current systems are discussed with regards to the observations made on the Earth's surface. Some useful and disruptive effects of the geomagnetic variations on navigation, shortwave radio communication, space satellite orbits and other technological systems are discussed.

  18. The International Geomagnetic Reference Field, 2005

    USGS Publications Warehouse

    Rukstales, Kenneth S.; Love, Jeffrey J.

    2007-01-01

    This is a set of five world charts showing the declination, inclination, horizontal intensity, vertical component, and total intensity of the Earth's magnetic field at mean sea level at the beginning of 2005. The charts are based on the International Geomagnetic Reference Field (IGRF) main model for 2005 and secular change model for 2005-2010. The IGRF is referenced to the World Geodetic System 1984 ellipsoid. Additional information about the USGS geomagnetism program is available at: http://geomag.usgs.gov/

  19. How the geomagnetic field vector reverses polarity

    USGS Publications Warehouse

    Prevot, M.; Mankinen, E.A.; Gromme, C.S.; Coe, R.S.

    1985-01-01

    A highly detailed record of both the direction and intensity of the Earth's magnetic field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals. ?? 1985 Nature Publishing Group.

  20. Geomagnetic main field modeling using magnetohydrodynamic constraints

    NASA Technical Reports Server (NTRS)

    Estes, R. H.

    1985-01-01

    The influence of physical constraints are investigated which may be approximately satisfied by the Earth's liquid core on models of the geomagnetic main field and its secular variation. A previous report describes the methodology used to incorporate nonlinear equations of constraint into the main field model. The application of that methodology to the GSFC 12/83 field model to test the frozen-flux hypothesis and the usefulness of incorporating magnetohydrodynamic constraints for obtaining improved geomagnetic field models is described.

  1. Reducing automatically activated racial prejudice through implicit evaluative conditioning.

    PubMed

    Olson, Michael A; Fazio, Russell H

    2006-04-01

    The authors report a set of experiments that use an implicit evaluative conditioning procedure to reduce automatically activated racial prejudice in White participants in a short period and with relatively few trials. Experiment 1 demonstrated that participants were unaware of the repeated conditioned stimulus-unconditioned stimulus (CS-US) pairings of Black-good and White-bad. In Experiment 2, the procedure was found to be effective in reducing prejudice as indicated by an evaluative priming measure of automatically activated racial attitudes. In Experiment 3, this reduction in prejudice was found to persist throughout a 2-day separation between the conditioning procedure and the administration of the dependent measure. The implications of the present findings for the persistence of automatically activated racial prejudice are discussed.

  2. Which Solar and Geomagnetic Drivers Control Earth's Upper Atmosphere Thermostat?

    NASA Astrophysics Data System (ADS)

    Knipp, D.; Mlynczak, M. G.; McGranaghan, R. M.; Kilcommons, L. M.

    2015-12-01

    Nitric Oxide (NO) is a trace component of Earth's upper atmosphere that allows Earth's thermosphere to cool in response to energy input from solar extreme ultraviolet (EUV) photons and geomagnetic activity. When created and excited, NO molecules provide a natural thermostat via infrared radiative emissions [Kockarts, 1980]. A record of this cooling over the last 13 years has been provided by Mlynczak et al. [2014]. Nitric Oxide emissions in concert with EUV photons, auroral particles, and neutral thermosphere circulation determine if geomagnetic storms will deliver a sudden powerful upheaval of Earth's upper atmosphere or a damped event. In this talk I will review recent findings about the forecastability of solar and magnetospheric control of this important thermospheric trace constituent. In particular, I will discuss the role of pseudo-streamers and helmet streamers in the solar wind, and the possible role of magnetic cloud orientation, in determining the extent of thermospheric NO storm response. Anticipating the thermospheric NO response to geomagnetic storms is a next step in improving satellite drag forecasting.

  3. Predicting ground electric field due to geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Nair, M. C.; Püthe, C.; Kuvshinov, A. V.

    2013-12-01

    Electric field induced in the ground by geomagnetic disturbances drives currents in the power transmission grids, telecommunication lines or buried pipelines. These currents, known as Geomagnetically Induced Currents (GIC) are known to cause service disruptions. This effect is maximal at high latitudes due to the presence of strong polar electrojet currents. However both observations and models show that GIC caused by ring current intensifications also pose a risk at low- and mid-latitude locations, where majority of systems vulnerable to GIC are installed. A technique to model geoelectric field induced by the magnetospheric currents in a 3D conductivity model of the Earth is presented by Püthe & Kuvshinov (2013). We extend this work by predicting the induced geoelectric field solely based on Disturbance storm time index (Dst), a measure of ring current activity. Two major components of this effort are 1) Pre-computed 3D electromagnetic response of the ground to a unit magnetopsheric (P01) source and 2) Forecasted Dst data (Temerin & Li, 2002; 2006) from Advanced Composition Explorer (ACE) satellite at the L1 Lagrange point. Depending on the solar wind speed, the Dst forecasts are available approximately 1 hour in advance. The pre-computed response function for a site is multiplied by the Dst data in frequency domain to obtain predicted electric field for that location. Validating our approach, the predicted geoelectric field compares favorably with observed data from an ocean bottom electromagnetic array in the Pacific Ocean during the geomagnetic storm of April 2000. We also compare data from USArray magnetotelluric stations operational during the geomagnetic storm of October 2011. In this case, the results are site specific, with varying degrees of model fit. This indicates the influence of local surface conductivity inhomogeneities on the observed geoelectric data. Averaging data from adjacent stations seems to improve the fit with the prediction.

  4. F2 region response to geomagnetic disturbances across Indian latitudes: O(1S) dayglow emission

    NASA Astrophysics Data System (ADS)

    Upadhayaya, A. K.; Gupta, Sumedha; Brahmanandam, P. S.

    2016-03-01

    The morphology of ionospheric storms has been investigated across equatorial and low latitudes of Indian region. The deviation in F2 region characteristic parameters (foF2 and h'F) along with modeled green line dayglow emission intensities is examined at equatorial station Thiruvananthapuram (8.5°N, 76.8°E, 0.63°S geomagnetic latitude) and low-latitude station Delhi (28.6°N, 77.2°E,19.2°N geomagnetic latitude) during five geomagnetic storm events. Both positive and negative phases have been noticed in this study. The positive storm phase over equatorial station is found to be more frequent, while the drop in ionization in most of the cases was observed at low-latitude station. It is concluded that the reaction as seen at different ionospheric stations may be quite different during the same storm depending on both the geographic and geomagnetic coordinates of the station, storm intensity, and the storm onset time. Modulation in the F2 layer critical frequency at low and equatorial stations during geomagnetic disturbance of 20-23 November 2003 was caused by the storm-induced changes in O/N2. It is also found that International Reference Ionosphere 2012 model predicts the F2 layer characteristic (foF2 and h'F) parameters at both the low and equatorial stations during disturbed days quite reasonably. A simulative approach in GLOW model developed by Solomon is further used to estimate the changes in the volume emission rate of green line dayglow emission under quiet and strong geomagnetic conditions. It is found that the O(1S) dayglow thermospheric emission peak responds to varying geomagnetic conditions.

  5. Geomagnetically trapped energetic helium nuclei

    SciTech Connect

    Chen, J.; Gregory Guzik, T.; Wefel, J.P.; Roger Pyle, K.; Cooper, J.F.

    1996-07-01

    Geomagnetically trapped helium nuclei, at high energy ({approximately}40{endash}100 MeV/nucleon), have been measured by the ONR-604 instrument during the 1990/1991 CRRES mission. The ONR-604 instrument resolved the isotopes of helium with a mass resolution of 0.1 amu. The energetic helium observed at {ital L}{lt}2.3 have a pitch angle distribution peaking perpendicular to the local magnetic field, which is characteristic of a trapped population. Both the trapped {sup 3}He and {sup 4}He show two peaks at {ital L}=1.2 and 1.9. Each isotope{close_quote}s flux, in each peak, can be characterized by a power law energy spectrum. The energy spectrum of the {sup 3}He is different from that of {sup 4}He, indicating that the {sup 3}He/{sup 4}He ratio is energy dependent. Over the energy range of 51{endash}86 MeV/nucleon, the {sup 3}He/{sup 4}He ratio is 8.7{plus_minus}3.1 at {ital L}=1.1{endash}1.5 and is 2.4{plus_minus}0.6 at {ital L}=1.5{endash}2.3. The trapped helium counting rates decrease gradually with time during the CRRES mission, when the anomalous component is excluded from the inner heliosphere, indicating that these high energy ions were not injected by flares during this time period. The decrease in intensity is attributed mainly to the events around {ital L}=1.9. The helium around {ital L}=1.2, dominated by {sup 3}He, does not show a significant temporal evolution, which implies a long-term energetic trapped {sup 3}He population. Two possible origins of the geomagnetically trapped helium isotopes are the interactions of energetic protons with the upper atmosphere and/or the inward diffusion and acceleration of helium ions due to electric-field fluctuations. {copyright} {ital 1996 American Institute of Physics.}

  6. Solar air-conditioning-active, hybrid and passive

    SciTech Connect

    Yellott, J. I.

    1981-04-01

    After a discussion of summer air conditioning requirements in the United States, active, hybrid, and passive cooling systems are defined. Active processes and systems include absorption, Rankine cycle, and a small variety of miscellaneous systems. The hybrid solar cooling and dehumidification technology of desiccation is covered as well as evaporative cooling. The passive solar cooling processes covered include convective, radiative and evaporative cooling. Federal and state involvement in solar cooling is then discussed. (LEW)

  7. Relationship Between Human Physiological Parameters And Geomagnetic Variations Of Solar Origin

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.

    This study attempts to assess the influence of increased geomagnetic activity on some human physiological parameters. The blood pressure, heart rate and general well-being of 86 volunteers were measured (the latter by means of a standardized questionnaire) on work days in autumn 2001 (01/10 to 09/11) and in spring 2002 (08/04 to 28/05). These periods were chosen because of maximal expected geomagnetic activity. Altogether, 2799 recordings were obtained and analysed. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters under consideration. The three factors were the following: 1) planetary geomagnetic activity level estimated by Ap-index and divided into five levels; 2) gender - males and females; 3) blood pressure degree - persons in the group examined were divided into hypotensive, normotensive and hypertensive. Post hoc analysis was performed to elicit the significance of differences in the factors' levels. The average arterial blood pressure of the group was found to increase significantly with the increase of geomagnetic activity level. The average increment of systolic and diastolic blood pressure reached 9%, which deserves attention from a medical point of view. This effect was present irrespectively of gender. Results obtained suppose that hypertensive persons have the highest sensitivity and the hypotensive persons have the lowest sensitivity of the arterial blood pressure to increase of geomagnetic activity. The results did not show significant changes in the heart rate. The percentage of the persons who reported subjective psycho-physiological complaints was also found to increase significantly with the geomagnetic activity increase. During severe geomagnetic storms 30% of the persons examined reported subjective complaints and the highest sensitivity was revealed for the hypertensive females. The results obtained add further evidence that blood pressure seems to be affected by geomagnetic

  8. Magnetic Signatures of Ionospheric and Magnetospheric Current Systems During Geomagnetic Quiet Conditions—An Overview

    NASA Astrophysics Data System (ADS)

    Olsen, Nils; Stolle, Claudia

    2016-09-01

    High-precision magnetic measurements taken by LEO satellites (flying at altitudes between 300 and 800 km) allow for studying the ionospheric and magnetospheric processes and electric currents that causes only weak magnetic signature of a few nanotesla during geomagnetic quiet conditions. Of particular importance for this endeavour are multipoint observations in space, such as provided by the Swarm satellite constellation mission, in order to better characterize the space-time-structure of the current systems. Focusing on geomagnetic quiet conditions, we provide an overview of ionospheric and magnetospheric sources and illustrate their magnetic signatures with Swarm satellite observations.

  9. Geomagnetic substorm association of plasmoids

    SciTech Connect

    Moldwin, M.B.; Hughes, W.J. )

    1993-01-01

    The relationship of geomagnetic substorms and plasmoids is examined by determining the correlation of the 366 plasmoids identified by Moldwin and Hughes (1992) with ground auroral zone magnetograms and geosynchronous particle data signatures of substorm onsets. Over 84% of the plasmoid events occurred between 5 and 60 min after a substorm onset. We also find near one-to-one correlation between large isolated substorm signatures in the near-Earth region and signatures consistent with a passing plasmoid in the distant tail (i.e., a traveling compression region, or an actual plasmoid observation). However, there does not appear to be an absolute correspondence of every substorm onset to a plasmoid signature in the deep tail especially, for periods of prolonged disturbance that have multiple substorm insets. A correlation of inter-planetary magnetic field B. south with plasmoid observations was also found. The locations of the near- and far-Earth reconnection sites are estimated using the time of flight of the plasmoids from substorm onset to their observation at ISEE 3. The estimates of the near- and far-Earth reconnection sites are highly variable and range from 10 to 140 RE, 32 refs., 4 figs. 2 tabs.

  10. On Geomagnetism and Paleomagnetism I

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    2000-01-01

    A partial description of Earth's broad scale, core-source magnetic field has been developed and tested three ways. The description features an expected, or mean, spatial magnetic power spectrum that is approximately inversely proportional to horizontal wavenumber atop Earth's core. This multipole spectrum describes a magnetic energy range; it is not steep enough for Gubbins' magnetic dissipation range. Temporal variations of core multipole powers about mean values are to be expected and are described statistically, via trial probability distribution functions, instead of deterministically, via trial solution of closed transport equations. The distributions considered here are closed and neither require nor prohibit magnetic isotropy. The description is therefore applicable to, and tested against, both dipole and low degree non-dipole fields. In Part 1, a physical basis for an expectation spectrum is developed and checked. The description is then combined with main field models of twentieth century satellite and surface geomagnetic field measurements to make testable predictions of the radius of Earth's core. The predicted core radius is 0.7% above the 3480 km seismological value. Partial descriptions of other planetary dipole fields are noted.

  11. Geomagnetic Field Modeling with DMSP

    NASA Astrophysics Data System (ADS)

    Alken, P.; Redmon, R. J.; Rich, F. J.; Maus, S.; Luhr, H.

    2013-12-01

    The Defense Meteorological Satellite Program (DMSP) launches and maintains a network of satellites to monitor the meteorological, oceanographic, and solar-terrestrial physics environments. In the past decade, geomagnetic field modelers have focused much attention on magnetic measurements from missions such as CHAMP, Oersted and SAC-C. With the completion of the CHAMP mission in 2010, there have been limited satellite-based vector and scalar magnetic field measurements available for main field modeling. In this study, we investigate the feasibility of using the Special Sensor Magnetometer (SSM) instrument onboard DMSP for main field modeling. These vector field measurements are calibrated to compute instrument timing shifts, scale factors, offsets, and non-orthogonalities in the fluxgate magnetometer cores. Euler angles are then computed to determine the orientation of the vector magnetometer with respect to a local coordinate system. We fit a degree 12 main field model to the dataset and compare with similar models such as the World Magnetic Model (WMM) and IGRF. Initial results indicate that the DMSP dataset will be a valuable source for main field modeling for the years between CHAMP and the upcoming Swarm mission.

  12. Experimental induction of intermale aggressive behavior in limbic epileptic rats by weak, complex magnetic fields: implications for geomagnetic activity and the modern habitat?

    PubMed

    St-Pierre, L S; Persinger, M A; Koren, S A

    1998-12-01

    In three separate experiments, groups (4/group) of male rats with limbic epilepsy were exposed for 80 min every 24 hr during the midscotophase for 24 successive days to sham-field conditions or to one of four complex patterns of magnetic fields whose average intensities ranged between 20 nT to 500 nT. The numbers of episodes of boxing, biting, mounting, eating, drinking and grooming were then recorded each night during the latter 20 min. Moderately strong statistically significant interactions occurred between the presence or absence of the field and the pattern of the field explained 25% and 50% of the variance in the numbers of biting and boxing responses, respectively. Other behaviors were not affected. The results suggest that group aggression can be increased or decreased as a function of the temporal characteristics and morphology (shape) of the applied magnetic field.

  13. Conditions of activity bubble uniqueness in dynamic neural fields.

    PubMed

    Mikhailova, Inna; Goerick, Christian

    2005-02-01

    Dynamic neural fields (DNFs) offer a rich spectrum of dynamic properties like hysteresis, spatiotemporal information integration, and coexistence of multiple attractors. These properties make DNFs more and more popular in implementations of sensorimotor loops for autonomous systems. Applications often imply that DNFs should have only one compact region of firing neurons (activity bubble), whereas the rest of the field should not fire (e.g., if the field represents motor commands). In this article we prove the conditions of activity bubble uniqueness in the case of locally symmetric input bubbles. The qualitative condition on inhomogeneous inputs used in earlier work on DNFs is transfered to a quantitative condition of a balance between the internal dynamics and the input. The mathematical analysis is carried out for the two-dimensional case with methods that can be extended to more than two dimensions. The article concludes with an example of how our theoretical results facilitate the practical use of DNFs. PMID:15685393

  14. Addressing Impacts of Geomagnetic Disturbances on the North American Bulk Power System

    NASA Astrophysics Data System (ADS)

    Rollison, Eric; Moura, John; Lauby, Mark

    2011-08-01

    In a joint report issued in June 2010, the North American Electric Reliability Corporation (NERC) and the U.S. Department of Energy (DOE) identified geomagnetic disturbances as a high-impact, low-frequency (HILF) event risk to bulk power system reliability. The potential impact of geomagnetic disturbance events has gained renewed attention as recent studies have suggested that solar storms may be more severe and reach lower geographic latitudes than formerly expected and can affect bulk power system reliability. The most well known power system experience with geomagnetic disturbances in North America was the 13-14 March 1989 storm, which led to the collapse of the Hydro-Québec system in the early morning hours of 13 March 1989, lasting approximately 9 hours. NERC is actively addressing a range of HILF event risks to bulk power system reliability through the efforts of four of its task forces: Geomagnetic Disturbance, Spare Equipment Database, Cyber and Physical Attack, and Severe Impact Resilience. These task forces operate under the direction of three NERC committees: Planning, Operating, and Critical Infrastructure Protection. The NERC Geomagnetic Disturbance Task Force (GMDTF), which was established in September 2010, is charged with investigating the implications of geomagnetic disturbances to the reliability of bulk power systems and developing solutions to help mitigate these risks. The objective of these efforts is to develop models to better understand the nature and effects of coronal mass ejections (CMEs), the vulnerabilities of equipment, bulk power system design considerations, our ability to reduce the operational and real-time impacts of geomagnetic disturbances on the bulk power system, and restoration methods, as well as to inventory long-lead-time equipment. For more information on the current activities of the GMDTF, please visit: www.nerc.com/filez/gmdtf.html

  15. Mid-latitude Geomagnetic Field Analysis Using BOH Magnetometer: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Hwang, Jun-Ga; Choi, Kyu-Cheol; Lee, Jae-Jin; Park, Young-Deuk; Ha, Dong-Hun

    2011-09-01

    Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Mt. Bohyun Observatory to measure the Earth's magnetic field variations in South Korea. We, in 2007, installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we provide the preliminary and the first statistical analysis using the BOH magnetometer installed at Mt. Bohyun Observatory. By superposed analysis, we find that daily variations of H, D, and Z shows similar tendency, that is, about 30 minutes before the meridian (11:28) a minimum appears and the time after about 3 hours and 30 minutes (15:28) a maximum appears. Also, a quiet interval start time (19:06) is near the sunset time, and a quiet interval end time (06:40) is near the sunrise time. From the sunset to the sunrise, the value of H has a nearly constant interval, that is, the sun affects the changes in H values. Seasonal variations show similar dependences to the sun. Local time variations show that noon region has the biggest variations and midnight region has the smallest variations. We compare the correlations between geomagnetic variations and activity indices as we expect the geomagnetic variation would contain the effects of geomagnetic activity variations. As a result, the correlation coefficient between H and Dst is the highest (r = 0.947), and other AL, AE, AU index and showed a high correlation. Therefore, the effects of geomagnetic storms and geomagnetic substorms might contribute to the geomagnetic changes significantly.

  16. Impact of the lower atmosphere on the ionosphere response to a geomagnetic superstorm

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.

    2016-09-01

    Numerical simulations in the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM) are performed to elucidate the impacts of lower atmosphere forcing on the ionosphere response to a geomagnetic superstorm. In particular, how the ionosphere variability due to the October 2003 Halloween storm would be different if it occurred in January coincident with a major sudden stratosphere warming (SSW) event is investigated. The TIE-GCM simulations reveal that the E× B vertical drift velocity and total electron content (TEC) respond differently to the geomagnetic forcing when the lower atmosphere forcing is representative of SSW conditions compared to climatological lower atmosphere forcing conditions. Notably, the storm time variations in the E× B vertical drift velocity differ when the SSW-induced zonal mean and tidal variability in the lower thermosphere are considered, and this is in part due to effects of the SSW on the equatorial ionosphere being potentially misinterpreted as being of geomagnetic origin. Differences in the TEC response to the geomagnetic storm can be up to 100% (˜30 TEC unit (TECU: 1 TECU = 1016 el m-2)) of the storm-induced TEC change, and the temporal variability of the TEC during the storm recovery phase is considerably different if SSW effects are considered. The results demonstrate that even during periods of extreme geomagnetic forcing, it is important to consider the effects of lower atmosphere forcing on the ionosphere variability.

  17. Probing geomagnetic storm-driven magnetosphere-ionosphere dynamics in D-region ionosphere using VLF signal propagation characteristics

    NASA Astrophysics Data System (ADS)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip Kumar; Ogunmodimu, Olugbenga

    2016-07-01

    When propagating in the Earth-ionosphere waveguide, the amplitude and phase of VLF/LF radio signals are sensitive to changes in the electrical conductivity of the lower ionosphere. This characteristic makes it useful in studying sudden ionospheric disturbances, especially those related to prompt X-ray flux output from solar flares and gamma ray bursts (GRBs). However, strong geomagnetic disturbances and/or storm conditions are known to produce large and global ionospheric disturbances, which can significantly affect VLF radio propagation in the D region ionosphere. Diurnal VLF signature may also convey other important information, especially those related to geomagnetic disturbance/storm induced ionospheric changes. In this paper, using the data of three propagation paths (at latitudes 40-54º), we analyze in detail the trend of anomalies of VLF diurnal signal under varying solar and geomagnetic space environmental conditions to identify possible geomagnetic footprints on the D region ionosphere.

  18. Hippocampal unit activity during classical aversive and appetitive conditioning.

    PubMed

    Segal, M; Disterhoft, J F; Olds, J

    1972-02-18

    Rats were trained with a tone being followed by either food or electric shock, on alternate days. Unit activity during application of the conditioned stimulus was recorded from the dorsal hippocampus. The results indicate differentiation of the hippocampal system. Dentate units respond by augmentation to a conditioned stimulus which leads to food and by inhibition to the same stimulus when it precedes electric shock. The hippocampus proper responds by augmentation in both situations. The intensity of the hippocampal response to the conditioned stimulus on the first day of training is higher if the unconditioned stimulus is food than if it is electric shock. These data cast light on the functions of the dorsal dentate-hippocampal connections and the hippocampus proper during aversive and appetitive conditioning.

  19. The Livingston Island Geomagnetic and Ionospheric Observatory

    NASA Astrophysics Data System (ADS)

    Altadill, David; Marsal, Santiago; Blanch, Estefania; Miquel Torta, J.; Quintana-Seguí, Pere; Germán Solé, J.; Cid, Òscar; José Curto, Juan; Ibáñez, Miguel; Segarra, Antoni; Lluís Pijoan, Joan; Juan, Juan Miguel

    2014-05-01

    The Ebre Observatory Institute manages a geophysical observatory installed at the Spanish Antarctic Station (SAS) Juan Carlos I. It was set up in 1995 and it has been updated yearly by our team throughout several projects carried out since then. Nowadays, it hosts a magnetic station providing 1-second data of the 3 components (X, Y, Z) and the total force (F) during the entire year, and an ionospheric station providing vertical and oblique data during austral summer. This observatory has provided long data series of high scientific value from this remote region of the Earth. They have been used to improve the knowledge of the climate and weather behavior of the geomagnetic field and ionosphere in the area, and to model and expand the capacity of data transmission. This contribution aims to present a brief review of the instruments installed at SAS, the research results obtained from their data, and the developing activities under the current project. Finally, future perspectives are outlined with regard to adapting our geophysical observatory to the evolving needs of observatory practice.

  20. Geomagnetism during solar cycle 23: Characteristics.

    PubMed

    Zerbo, Jean-Louis; Amory-Mazaudier, Christine; Ouattara, Frédéric

    2013-05-01

    On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996-2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT) and yearly averaged solar wind speed (364 km/s) are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s), associated to the highest value of the yearly averaged aa index (37 nT). We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century) study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum. PMID:25685427

  1. Geomagnetism during solar cycle 23: Characteristics

    PubMed Central

    Zerbo, Jean-Louis; Amory-Mazaudier, Christine; Ouattara, Frédéric

    2012-01-01

    On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996–2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT) and yearly averaged solar wind speed (364 km/s) are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s), associated to the highest value of the yearly averaged aa index (37 nT). We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century) study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum. PMID:25685427

  2. Analysis of Geomagnetic Disturbances and Cosmic Ray Intensity Variations in Relation to Medical Data from Rome

    NASA Astrophysics Data System (ADS)

    Giannaropoulou, E.; Papailiou, M.; Mavromichalaki, H.; Tsipis, A.

    2010-07-01

    Over the last few years many studies have been conducted concerning the possible influence of geomagnetic and solar activity and cosmic ray activity on human physiological state and in particular on human cardio - health state. As it is shown the human organism is sensitive to environmental changes and reacts to them through a series of variations of its physiological parameters such as heart rate, arterial systolic and diastolic blood pressure, etc. In this paper daily mean values of heart rate, as they were registered for a group of 2.028 volunteers during medical examinations in the Polyclinico Tor Vergata, Rome, Italy are analyzed in relation to daily cosmic ray intensity variations, as measured by the Neutron Monitor of the University of Athens and daily variations of the geomagnetic indices Dst, Ap and Kp. The results from this study show that geomagnetic activity changes and cosmic rays intensity variations may regulate the human homeostasis.

  3. Arabidopsis thaliana root elongation growth is sensitive to lunisolar tidal acceleration and may also be weakly correlated with geomagnetic variations

    PubMed Central

    Barlow, Peter W.; Fisahn, Joachim; Yazdanbakhsh, Nima; Moraes, Thiago A.; Khabarova, Olga V.; Gallep, Cristiano M.

    2013-01-01

    Background Correlative evidence suggests a relationship between the lunisolar tidal acceleration and the elongation rate of arabidopsis roots grown under free-running conditions of constant low light. Methods Seedlings of Arabidopsis thaliana were grown in a controlled-climate chamber maintained at a constant temperature and subjected to continuous low-level illumination from fluorescent tubes, conditions that approximate to a ‘free-running’ state in which most of the abiotic factors that entrain root growth rates are excluded. Elongation of evenly spaced, vertical primary roots was recorded continuously over periods of up to 14 d using high temporal- and spatial-resolution video imaging and were analysed in conjunction with geophysical variables. Key Results and Conclusions The results confirm the lunisolar tidal/root elongation relationship. Also presented are relationships between the hourly elongation rates and the contemporaneous variations in geomagnetic activity, as evaluated from the disturbance storm time and ap indices. On the basis of time series of root elongation rates that extend over ≥4 d and recorded at different seasons of the year, a provisional conclusion is that root elongation responds to variation in the lunisolar force and also appears to adjust in accordance with variations in the geomagnetic field. Thus, both lunisolar tidal acceleration and the geomagnetic field should be considered as modulators of root growth rate, alongside other, stronger and more well-known abiotic environmental regulators, and perhaps unexplored factors such as air ions. Major changes in atmospheric pressure are not considered to be a factor contributing to oscillations of root elongation rate. PMID:23532042

  4. Bats Use Geomagnetic Field: Behavior and Mechanism

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Tian, L.; Zhang, B.; Zhu, R.

    2015-12-01

    It has been known that numerous animals can use the Earth's magnetic field for spatial orientation and long-distance navigation, nevertheless, how animals can respond to the magnetic field remain mostly ambiguous. The intensities of the global geomagnetic field varies between 23 and 66 μT, and the geomagnetic field intensity could drop to 10% during geomagnetic polarity reversals or geomagnetic excursions. Such dramatic changes of the geomagnetic field may pose a significant challenge for the evolution of magnetic compass in animals. For examples, it is vital whether the magnetic compass can still work in such very weak magnetic fields. Our previous experiment has demonstrated that a migratory bat (Nyctalus plancyi) uses a polarity compass for orientation during roosting when exposed to an artificial magnetic field (100 μT). Recently, we experimentally tested whether the N. plancyi can sense very weak magnetic fields that were even lower than those of the present-day geomagnetic field. Results showed: 1) the bats can sense the magnetic north in a field strength of present-day local geomagnetic field (51μT); 2) As the field intensity decreased to only 1/5th of the natural intensity (10 μT), the bats still responded by positioning themselves at the magnetic north. Notably, as the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT). Hence, N. plancyi is able to detect the direction of a magnetic field with intensity range from twice to 1/5th of the present-day field strength. This allows them to orient themselves across the entire range of present-day global geomagnetic field strengths and sense very weak magnetic fields. We propose that this high sensitivity might have evolved in bats as the geomagnetic field strength varied and the polarity reversed tens of times over the past fifty million years since the origin of bats. The physiological mechanisms underlying

  5. Relationship between human physiological parameters and geomagnetic variations of solar origin

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.

    Results presented concern influence of increased geomagnetic activity on some human physiological parameters. The blood pressure and heart rate of 86 volunteers were measured on working days in autumn 2001 (01/10 09/11) and in spring 2002 (08/04 28/05). These periods were chosen because of maximal expected geomagnetic activity. Altogether 2799 recordings were obtained and analysed. Questionnaire information about subjective psycho-physiological complaints was also gathered. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters under consideration. The factors were the following: (1) planetary geomagnetic activity level estimated by Ap-index and divided into five levels; (2) gender males and females; (3) blood pressure degree persons in the group examined were divided into hypotensive, normotensive and hypertensive. Post hoc analysis was performed to elicit the significance of differences in the factors’ levels. The average arterial blood pressure of the group was found to increase significantly with the increase of geomagnetic activity level. The average increment of systolic and diastolic blood pressure of the group examined reached 9%. This effect was present irrespectively of gender. Results obtained suppose that hypertensive persons have the highest sensitivity and the hypotensive persons have the lowest sensitivity of the arterial blood pressure to increase of geomagnetic activity. The results did not show significant changes in the heart rate. The percentage of the persons who reported subjective psycho-physiological complaints was also found to increase significantly with the geomagnetic activity increase and the highest sensitivity was revealed for the hypertensive females.

  6. Study of the mid-latitude ionospheric response to geomagnetic storms in the European region

    NASA Astrophysics Data System (ADS)

    Berényi, Kitti Alexandra; Barta, Veronika; Kis, Arpad

    2016-07-01

    Geomagnetic storms affect the ionospheric regions of the terrestrial upper atmosphere through different physical and atmospheric processes. The phenomena that can be regarded as a result of these processes, generally is named as "ionospheric storm". The processes depend on altitude, segment of the day, the geomagnetic latitude and longitude, strength of solar activity and the type of the geomagnetic storm. We examine the data of ground-based radio wave ionosphere sounding measurements of European ionospheric stations (mainly the data of Nagycenk Geophysical Observatory) in order to determine how and to what extent a geomagnetic disturbance of a certain strength affects the mid-latitude ionospheric regions in winter and in summer. For our analysis we used disturbed time periods between November 2012 and June 2015. Our results show significant changing of the ionospheric F2 layer parameters on strongly disturbed days compared to quiet ones. We show that the critical frequencies (foF2) increase compared to their quiet day value when the ionospheric storm was positive. On the other hand, the critical frequencies become lower, when the storm was negative. In our analysis we determined the magnitude of these changes on the chosen days. For a more complete analysis we compare also the evolution of the F2 layer parameters of the European ionosonde stations on a North-South geographic longitude during a full storm duration. The results present the evolution of an ionospheric storm over a geographic meridian. Furthermore, we compared the two type of geomagnetic storms, namely the CME caused geomagnetic storm - the so-called Sudden impulse (Si) storms- and the HSS (High Speed Solar Wind Streams) caused geomagnetic storms -the so-called Gradual storms (Gs)- impact on the ionospheric F2-layer (foF2 parameter). The results show a significant difference between the effect of Si and of the Gs storms on the ionospheric F2-layer.

  7. The latitudinal distribution of the baseline geomagnetic field during the March 17, 2015 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Alberti, Tommaso; Piersanti, Mirko; Lepreti, Fabio; Vecchio, Antonio; De Michelis, Paola; Villante, Umberto; Carbone, Vincenzo

    2016-04-01

    Geomagnetic storms (GS) are global geomagnetic disturbances that result from the interaction between magnetized plasma that propagates from the Sun and plasma and magnetic fields in the near-Earth space plasma environment. The Dst (Disturbance Storm Time) global Ring Current index is still taken to be the definitive representation for geomagnetic storm and is used widely by researcher. Recent in situ measurements by satellites passing through the ring-current region (i.e. Van Allen probes) and computations with magnetospheric field models showed that there are many other field contributions on the geomagnetic storming time variations at middle and low latitudes. Appling the Empirical Mode Decomposition [Huang et al., 1998] to magnetospheric and ground observations, we detect the different magnetic field contributions during a GS and introduce the concepts of modulated baseline and fluctuations of the geomagnetic field. In this work, we apply this method to study the latitudinal distribution of the baseline geomagnetic field during the St. Patrick's Day Geomagnetic Storm 2015 in order to detect physical informations concerning the differences between high-latitude and equatorial ground measurements.

  8. Catalyst dispersion and activity under conditions of temperature- staged liquefaction

    SciTech Connect

    Davis, A.; Schobert, H.H.; Mitchell, G.D.; Artok, L.

    1992-02-01

    The general objectives of this research are (1) to investigate the use of highly dispersed catalysts for the pretreatment of coal by mild hydrogenation, (2) to identify the active forms of catalysts under reaction conditions and (3) to clarify the mechanisms of catalysis. The ultimate objective is to ascertain if mild catalytic hydrogenation resulting in very limited or no coal solubilization is an advantageous pretreatment for the transformation of coal into transportable fuels. The experimental program will focus upon the development of effective methods of impregnating coal with catalysts, evaluating the conditions under which the catalysts are most active and establishing the relative impact of improved impregnation on conversion and product distributions obtained from coal hydrogenation.

  9. Proposed geomagnetic control of semiannual waves in the mesospheric zonal wind

    NASA Technical Reports Server (NTRS)

    Belmont, A. D.; Nastrom, G. D.; Mayr, H. G.

    1975-01-01

    The polar semiannual oscillation in zonal wind explains midwinter weakening of the polar vortex and the relatively short stratospheric and mesospheric summer easterlies. The phase of the wind oscillation is equinoctial, as is the phase of the semiannual component in magnetic storm activity. For a given altitude, the contours of amplitude of the semiannual wind oscillation have less variability in geomagnetic than in geographic coordinates. It is suggested that the polar wind oscillations are caused by the semiannual maxima in magnetic storm activity, which lead to electron dissociation of O2 into O, in turn increasing ozone more rapidly than the dissociation of N2 destroys ozone, and inducing a semiannual variation in the thermal and wind fields. This implies that geomagnetic processes may cause or affect the development of sudden warmings. As the tropical semiannual wind oscillation is symmetric about the geomagnetic equator, the same processes may also influence the location of the tropical wind wave.

  10. Magnetospheric mapping with quantitative geomagnetic field models

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Mead, G. D.

    1973-01-01

    The Mead-Fairfield geomagnetic field models were used to trace field lines between the outer magnetosphere and the earth's surface. The results are presented in terms of ground latitude and local time contours projected to the equatorial plane and into the geomagnetic tail. With these contours various observations can be mapped along field lines between high and low altitudes. Low altitudes observations of the polar cap boundary, the polar cusp, the energetic electron trapping boundary and the sunward convection region are projected to the equatorial plane and compared with the results of the model and with each other. The results provide quantitative support to the earlier suggestions that the trapping boundary is associated with the last closed field line in the sunward hemisphere, the polar cusp is associated with the region of the last closed field line, and the polar cap projects to the geomagnetic tail and has a low latitude boundary corresponding to the last closed field line.

  11. Scaling laws from geomagnetic time series

    USGS Publications Warehouse

    Voros, Z.; Kovacs, P.; Juhasz, A.; Kormendi, A.; Green, A.W.

    1998-01-01

    The notion of extended self-similarity (ESS) is applied here for the X - component time series of geomagnetic field fluctuations. Plotting nth order structure functions against the fourth order structure function we show that low-frequency geomagnetic fluctuations up to the order n = 10 follow the same scaling laws as MHD fluctuations in solar wind, however, for higher frequencies (f > l/5[h]) a clear departure from the expected universality is observed for n > 6. ESS does not allow to make an unambiguous statement about the non triviality of scaling laws in "geomagnetic" turbulence. However, we suggest to use higher order moments as promising diagnostic tools for mapping the contributions of various remote magnetospheric sources to local observatory data. Copyright 1998 by the American Geophysical Union.

  12. International Geomagnetic Reference Field: the third generation.

    USGS Publications Warehouse

    Peddie, N.W.

    1982-01-01

    In August 1981 the International Association of Geomagnetism and Aeronomy revised the International Geomagnetic Reference Field (IGRF). It is the second revision since the inception of the IGRF in 1968. The revision extends the earlier series of IGRF models from 1980 to 1985, introduces a new series of definitive models for 1965-1976, and defines a provisional reference field for 1975- 1980. The revision consists of: 1) a model of the main geomagnetic field at 1980.0, not continuous with the earlier series of IGRF models together with a forecast model of the secular variation of the main field during 1980-1985; 2) definitive models of the main field at 1965.0, 1970.0, and 1975.0, with linear interpolation of the model coefficients specified for intervening dates; and 3) a provisional reference field for 1975-1980, defined as the linear interpolation of the 1975 and 1980 main-field models.-from Author

  13. Acoustical conditions for speech communication in active elementary school classrooms

    NASA Astrophysics Data System (ADS)

    Sato, Hiroshi; Bradley, John

    2005-04-01

    Detailed acoustical measurements were made in 34 active elementary school classrooms with typical rectangular room shape in schools near Ottawa, Canada. There was an average of 21 students in classrooms. The measurements were made to obtain accurate indications of the acoustical quality of conditions for speech communication during actual teaching activities. Mean speech and noise levels were determined from the distribution of recorded sound levels and the average speech-to-noise ratio was 11 dBA. Measured mid-frequency reverberation times (RT) during the same occupied conditions varied from 0.3 to 0.6 s, and were a little less than for the unoccupied rooms. RT values were not related to noise levels. Octave band speech and noise levels, useful-to-detrimental ratios, and Speech Transmission Index values were also determined. Key results included: (1) The average vocal effort of teachers corresponded to louder than Pearsons Raised voice level; (2) teachers increase their voice level to overcome ambient noise; (3) effective speech levels can be enhanced by up to 5 dB by early reflection energy; and (4) student activity is seen to be the dominant noise source, increasing average noise levels by up to 10 dBA during teaching activities. [Work supported by CLLRnet.

  14. Large Geomagnetic Storms: Introduction to Special Section

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2010-01-01

    Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst < or = -100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section.

  15. Satellite data for geomagnetic field modeling

    NASA Astrophysics Data System (ADS)

    Langel, R. A.; Baldwin, R. T.

    1992-06-01

    Satellite measurements of the geomagnetic fields began with the launch of Sputnik 3 in May of 1958 and have continued sporadically. Spacecraft making significant contributions to main field geomagnetism will be reviewed and the characteristics of their data discussed, including coverage, accuracy, resolution and data availability. Of particular interest are Vanguard 3; Cosmos 49, Ogo's -2, -4, and -6; Magsat; DE-2; and POGS. Spacecraft make measurements on a moving platfrom above the ionosphere as opposed to measurements from fixed observatories and surveys, both below the ionosphere. Possible future missions, such as Aristoteles and GOS are reviewed.

  16. Satellite Data for Geomagnetic Field Modeling

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Baldwin, R. T.

    1992-01-01

    Satellite measurements of the geomagnetic fields began with the launch of Sputnik 3 in May of 1958 and have continued sporadically. Spacecraft making significant contributions to main field geomagnetism will be reviewed and the characteristics of their data discussed, including coverage, accuracy, resolution and data availability. Of particular interest are Vanguard 3; Cosmos 49, Ogo's -2, -4, and -6; Magsat; DE-2; and POGS. Spacecraft make measurements on a moving platfrom above the ionosphere as opposed to measurements from fixed observatories and surveys, both below the ionosphere. Possible future missions, such as Aristoteles and GOS are reviewed.

  17. Anencephalus, drinking water, geomagnetism and cosmic radiation.

    PubMed

    Archer, V E

    1979-01-01

    The mortality rates from anencephalus from 1950-1969 in Canadian cities are shown to be strongly correlated with city growth rate and with horizontal geomagnetic flux, which is directly related to the intensity of cosmic radiation. They are also shown to have some association with the magnesium content of drinking water. Prior work with these data which showed associations with magnesium in drinking water, mean income, latitude and longitude was found to be inadequate because it dismissed the observed geographic associations as having little biological meaning, and because the important variables of geomagnetism and city growth rate were overlooked. PMID:433919

  18. The Laschamp-Mono lake geomagnetic events and the extinction of Neanderthal: a causal link or a coincidence?

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Valladas, Hélène

    2010-12-01

    The causes of Neanderthal extinction and the transition with the modern man in Europe and Near East remain largely uncertain. The two main factors currently proposed are the arrival of a modern human competitor and/or the aptitude of the Neanderthals to survive rapidly changing climatic conditions. None of these hypotheses is fully satisfactory because the Neanderthals experienced other large climatic changes and the duration of overlap of the two populations remains largely unknown and even uncertain. No special attention has been given to the geomagnetic excursions of Laschamp and Mono Lake which are synchroneous with the extinction and were the most dramatic events encountered by the Neanderthals over the past 250 thousand years of their existence. During this period the geomagnetic field strength was considerably reduced and the shielding efficiency of the magnetosphere lowered, leaving energetic particles reach latitudes as low as 30°. The enhanced flux of high-energy protons (linked to solar activity) into the atmosphere yielded significant ozone depletion down to latitudes of 40-45°. A direct consequence was an increase of the UV-B radiations at the surface which might have reached at least 15-20% in Europe with significant impacts on health of human populations. We suggest that these conditions, added to some other factors, contributed to the demise of Neanderthal population.

  19. A time-compressed simulated geomagnetic storm influences the nest-exiting flight angles of the stingless bee Tetragonisca angustula.

    PubMed

    Esquivel, D M S; Corrêa, A A C; Vaillant, O S; de Melo, V Bandeira; Gouvêa, G S; Ferreira, C G; Ferreira, T A; Wajnberg, E

    2014-03-01

    Insects have been used as models for understanding animal orientation. It is well accepted that social insects such as honeybees and ants use different natural cues in their orientation mechanism. A magnetic sensitivity was suggested for the stingless bee Schwarziana quadripunctata, based on the observation of a surprising effect of a geomagnetic storm on the nest-exiting flight angles. Stimulated by this result, in this paper, the effects of a time-compressed simulated geomagnetic storm (TC-SGS) on the nest-exiting flight angles of another stingless bee, Tetragonisca angustula, are presented. Under an applied SGS, either on the horizontal or vertical component of the geomagnetic field, both nest-exiting flight angles, dip and azimuth, are statistically different from those under geomagnetic conditions. The angular dependence of ferromagnetic resonance (FMR) spectra of whole stingless bees shows the presence of organized magnetic nanoparticles in their bodies, which indicates this material as a possible magnetic detector.

  20. A time-compressed simulated geomagnetic storm influences the nest-exiting flight angles of the stingless bee Tetragonisca angustula

    NASA Astrophysics Data System (ADS)

    Esquivel, D. M. S.; Corrêa, A. A. C.; Vaillant, O. S.; de Melo, V. Bandeira; Gouvêa, G. S.; Ferreira, C. G.; Ferreira, T. A.; Wajnberg, E.

    2014-03-01

    Insects have been used as models for understanding animal orientation. It is well accepted that social insects such as honeybees and ants use different natural cues in their orientation mechanism. A magnetic sensitivity was suggested for the stingless bee Schwarziana quadripunctata, based on the observation of a surprising effect of a geomagnetic storm on the nest-exiting flight angles. Stimulated by this result, in this paper, the effects of a time-compressed simulated geomagnetic storm (TC-SGS) on the nest-exiting flight angles of another stingless bee, Tetragonisca angustula, are presented. Under an applied SGS, either on the horizontal or vertical component of the geomagnetic field, both nest-exiting flight angles, dip and azimuth, are statistically different from those under geomagnetic conditions. The angular dependence of ferromagnetic resonance (FMR) spectra of whole stingless bees shows the presence of organized magnetic nanoparticles in their bodies, which indicates this material as a possible magnetic detector.

  1. Cholinergic interneurons control local circuit activity and cocaine conditioning.

    PubMed

    Witten, Ilana B; Lin, Shih-Chun; Brodsky, Matthew; Prakash, Rohit; Diester, Ilka; Anikeeva, Polina; Gradinaru, Viviana; Ramakrishnan, Charu; Deisseroth, Karl

    2010-12-17

    Cholinergic neurons are widespread, and pharmacological modulation of acetylcholine receptors affects numerous brain processes, but such modulation entails side effects due to limitations in specificity for receptor type and target cell. As a result, causal roles of cholinergic neurons in circuits have been unclear. We integrated optogenetics, freely moving mammalian behavior, in vivo electrophysiology, and slice physiology to probe the cholinergic interneurons of the nucleus accumbens by direct excitation or inhibition. Despite representing less than 1% of local neurons, these cholinergic cells have dominant control roles, exerting powerful modulation of circuit activity. Furthermore, these neurons could be activated by cocaine, and silencing this drug-induced activity during cocaine exposure (despite the fact that the manipulation of the cholinergic interneurons was not aversive by itself) blocked cocaine conditioning in freely moving mammals.

  2. Neural net forecasting for geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Hernandez, J. V.; Tajima, T.; Horton, W.

    1993-01-01

    We use neural nets to construct nonlinear models to forecast the AL index given solar wind and interplanetary magnetic field (IMF) data. We follow two approaches: (1) the state space reconstruction approach, which is a nonlinear generalization of autoregressive-moving average models (ARMA) and (2) the nonlinear filter approach, which reduces to a moving average model (MA) in the linear limit. The database used here is that of Bargatze et al. (1985).

  3. Modelling of ionospheric irregularities during geomagnetic storms over African low latitude region

    NASA Astrophysics Data System (ADS)

    Mungufeni, Patrick

    2016-07-01

    In this study, empirical models of occurrence of ionospheric irregularities over low latitude African region during geomagnetic storms have been developed. The geomagnetic storms considered consisted of Dst ≤ -50 nT. GNSS-derived ionospheric Total Electron Content (TEC) data over Libreville, Gabon (NKLG) (0.35° N, 9.68° E, geographic, 8.05° S, magnetic) and Malindi, Kenya (MAL2) (2.99° S, 40.19° E, geographic, 12.42° S, magnetic) during 2000 - 2014 were used. Ionospheric irregularities at scale- lengths of a few kilometers and ˜400 m were represented with the rate of change of TEC index (ROTI). The inputs for the models are the local time, solar flux index, Auroral Electrojet index, day of the year, and the Dst index, while the output is the median ROTI during these given conditions. To develop the models, the ROTI index values were binned based on the input parameters and cubic B splines were then fitted to the binned data. Developed models using data over NKLG and MAL2 were validated with independent data over stations within 510 km and 680 km radius, respectively. The models captured the enhancements and inhibitions of the occurrence of the ionospheric irregularities during the storm period. The models even emulated these patterns in the various seasons, during medium and high solar activity conditions. The correlation coefficients for the validations were statistically significant and ranged from 0.58 - 0.73, while the percentage of the variance in the observed data explained by the modelled data ranged from 34 - 53.

  4. A case study of the thermospheric neutral wind response to geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Jiang, Guoying; Zhang, Shunrong; Wang, Wenbin; Yuan, Wei; Wu, Qian; Xu, Jiyao

    A minor geomagnetic storm (Kp=5) occurred on March 27-28, 2012. The response of the thermospheric neutral wind at ~ 250 km to this storm was investigated by the 630.0 nm nightglow measurements of Fabry-Perot interferometers (FPIs) over Xinglong (geographic location: 40.2N, 117.4E; geomagnetic location: 29.8N, 193.2E) and Millstone Hill (geographic location: 42.6N, 71.5W; geomagnetic location: 53.1N, 65.1W). Our results show that the minor storm on March 27-28, 2012 obviously effected on the thermospheric neutral winds over Xinglong and Millstone Hill, especially Millstone Hill had larger response because of its higher geomagnetic latitude. Another interesting result is that a small variation in geomagnetic activity (Kp=2.7) could enough introduce a clear disturbance in the nighttime thermospheric neutral wind over Millstone hill. NCAR-TIME-GCM (National Center for Atmospheric Research-Thermosphere Ionosphere Mesosphere Electrodynamics-General Circulation Model) was employed to study the evolution and mechanism of the thermospheric neutral wind response.

  5. Geomagnetic transmission of solar energetic protons during the geomagnetic disturbances of October 1989

    NASA Technical Reports Server (NTRS)

    Boberg, P. R.; Tylka, A. J.; Adams J. H., JR.; Flueckiger, E. O.; Kobel, E.

    1995-01-01

    Orbit-averaged geomagnetic transmission measurements during the large solar energetic particle events of October 1989 are presented using proton data from the NOAA-10 and GOES-7 satellies. The measurements are compared to geomagnetic transmission calculations determined by tracing particle trajectories through the combination of the International Geomagnetic Reference Field (IGRF) model and the 1989 Tsyganenko magnetospheric magnetic field model. The effective 'ring current' parameter in the 1989 Tsyganenko model based on the Dst data. Results are compared to calculations employing only the IGRF and to a parameterization of geomagnetically quiet-time cutoff rigidities derived from Cosmos/intercosmos observations. The 3-hour orbit-averaged results have approximately 15% accuracy during the October 1989 events.

  6. Psychopaths Show Enhanced Amygdala Activation during Fear Conditioning

    PubMed Central

    Schultz, Douglas H.; Balderston, Nicholas L.; Baskin-Sommers, Arielle R.; Larson, Christine L.; Helmstetter, Fred J.

    2016-01-01

    Psychopathy is a personality disorder characterized by emotional deficits and a failure to inhibit impulsive behavior and is often subdivided into “primary” and “secondary” psychopathic subtypes. The maladaptive behavior related to primary psychopathy is thought to reflect constitutional “fearlessness,” while the problematic behavior related to secondary psychopathy is motivated by other factors. The fearlessness observed in psychopathy has often been interpreted as reflecting a fundamental deficit in amygdala function, and previous studies have provided support for a low-fear model of psychopathy. However, many of these studies fail to use appropriate screening procedures, use liberal inclusion criteria, or have used unconventional approaches to assay amygdala function. We measured brain activity with BOLD imaging in primary and secondary psychopaths and non-psychopathic control subjects during Pavlovian fear conditioning. In contrast to the low-fear model, we observed normal fear expression in primary psychopaths. Psychopaths also displayed greater differential BOLD activity in the amygdala relative to matched controls. Inverse patterns of activity were observed in the anterior cingulate cortex (ACC) for primary versus secondary psychopaths. Primary psychopaths exhibited a pattern of activity in the dorsal and ventral ACC consistent with enhanced fear expression, while secondary psychopaths exhibited a pattern of activity in these regions consistent with fear inhibition. These results contradict the low-fear model of psychopathy and suggest that the low fear observed for psychopaths in previous studies may be specific to secondary psychopaths. PMID:27014154

  7. Psychopaths Show Enhanced Amygdala Activation during Fear Conditioning.

    PubMed

    Schultz, Douglas H; Balderston, Nicholas L; Baskin-Sommers, Arielle R; Larson, Christine L; Helmstetter, Fred J

    2016-01-01

    Psychopathy is a personality disorder characterized by emotional deficits and a failure to inhibit impulsive behavior and is often subdivided into "primary" and "secondary" psychopathic subtypes. The maladaptive behavior related to primary psychopathy is thought to reflect constitutional "fearlessness," while the problematic behavior related to secondary psychopathy is motivated by other factors. The fearlessness observed in psychopathy has often been interpreted as reflecting a fundamental deficit in amygdala function, and previous studies have provided support for a low-fear model of psychopathy. However, many of these studies fail to use appropriate screening procedures, use liberal inclusion criteria, or have used unconventional approaches to assay amygdala function. We measured brain activity with BOLD imaging in primary and secondary psychopaths and non-psychopathic control subjects during Pavlovian fear conditioning. In contrast to the low-fear model, we observed normal fear expression in primary psychopaths. Psychopaths also displayed greater differential BOLD activity in the amygdala relative to matched controls. Inverse patterns of activity were observed in the anterior cingulate cortex (ACC) for primary versus secondary psychopaths. Primary psychopaths exhibited a pattern of activity in the dorsal and ventral ACC consistent with enhanced fear expression, while secondary psychopaths exhibited a pattern of activity in these regions consistent with fear inhibition. These results contradict the low-fear model of psychopathy and suggest that the low fear observed for psychopaths in previous studies may be specific to secondary psychopaths.

  8. Psychopaths Show Enhanced Amygdala Activation during Fear Conditioning.

    PubMed

    Schultz, Douglas H; Balderston, Nicholas L; Baskin-Sommers, Arielle R; Larson, Christine L; Helmstetter, Fred J

    2016-01-01

    Psychopathy is a personality disorder characterized by emotional deficits and a failure to inhibit impulsive behavior and is often subdivided into "primary" and "secondary" psychopathic subtypes. The maladaptive behavior related to primary psychopathy is thought to reflect constitutional "fearlessness," while the problematic behavior related to secondary psychopathy is motivated by other factors. The fearlessness observed in psychopathy has often been interpreted as reflecting a fundamental deficit in amygdala function, and previous studies have provided support for a low-fear model of psychopathy. However, many of these studies fail to use appropriate screening procedures, use liberal inclusion criteria, or have used unconventional approaches to assay amygdala function. We measured brain activity with BOLD imaging in primary and secondary psychopaths and non-psychopathic control subjects during Pavlovian fear conditioning. In contrast to the low-fear model, we observed normal fear expression in primary psychopaths. Psychopaths also displayed greater differential BOLD activity in the amygdala relative to matched controls. Inverse patterns of activity were observed in the anterior cingulate cortex (ACC) for primary versus secondary psychopaths. Primary psychopaths exhibited a pattern of activity in the dorsal and ventral ACC consistent with enhanced fear expression, while secondary psychopaths exhibited a pattern of activity in these regions consistent with fear inhibition. These results contradict the low-fear model of psychopathy and suggest that the low fear observed for psychopaths in previous studies may be specific to secondary psychopaths. PMID:27014154

  9. Response of the H-geocorona to geomagnetic disturbances studied by TWINS Lyman-alpha data

    NASA Astrophysics Data System (ADS)

    Zoennchen, Jochen; Nass, Uwe; Fahr, Hans

    2016-04-01

    We have studied the variation of the exospheric H-density distribution during two geomagnetic storms of different strength in terms of their Dst-index values. This analysis is based on continuously monitored Lyman-alpha data observed by the TWINS1/2-LAD instruments. Since solar Lyman-alpha radiation is resonantly backscattered from geocoronal neutral hydrogen (H), the resulting resonance glow intensity in the optically thin regime is proportional to H-column density along the line of sight (LOS). We quantify the amplitude of the H-density's response to geomagnetic activity for different (observed) angular regions and radial Earth-distances. Interestingly the H-exosphere responded with a comparable density increase to both storms of different strength. Careful analysis of the geomagnetic H-density effect indicates that the temporal density response is well correlated with the Kp-index daily sum, but not with the Dst-index in case of the two analysed storms.

  10. Dynamic Geomagnetic Hazard Maps in Space Weather Operations

    NASA Astrophysics Data System (ADS)

    Rigler, E. J.; Pulkkinen, A. A.; Balch, C. C.; Wiltberger, M. J.

    2014-12-01

    Traditionally, the use of geomagnetic data in space weather operations has been limited to specific geographic coordinates (i.e., magnetic observatories), or to global indices that average magnetic measurements into latitudinal bands of relatively general space weather interest (e.g., Dst, Kp, AE). However, modern technological systems (e.g., power grids, directional drilling platforms) are beginning to require and request information about ground magnetic variations that is more tailored to a specific locale. One solution is to simply install magnetic observatories near every newly built technological system, but this is both economically and operationally impractical. We have chosen instead to adopt an optimal interpolation scheme that inverts for spherical elementary current systems (SECS, Amm-1997), which in turn are used to fill gaps between magnetic observatories. The SECS technique has undergone extensive scientific vetting over the last decade-and-a-half, and will soon be implemented operationally over the continental U.S. as a joint NASA-NOAA-USGS space weather data product, disseminated by the Space Weather Prediction Center (SWPC). Because it will employ a relatively sparse array of high-quality geomagnetic observatories as input, it is important to characterize its ability to reproduce spatial variations in geomagnetic field at sub-continental scales, so the Lyon-Fedder-Mobarry (LFM) global geospace model is used to generate realistic synthetic observations. These include virtual magnetic observatories as input, and a regular geographic grid to serve as a proxy for "ground truth". We look specifically at LFM output for the Whole Heliosphere Interval (WHI) in order to obtain statistically valid performance measures for a variety of quiet-to-moderate space weather conditions.

  11. Ionospheric response to great geomagnetic storms during solar cycle 23

    NASA Astrophysics Data System (ADS)

    Merline Matamba, Tshimangadzo; Bosco Habarulema, John

    2016-07-01

    The analyses of ionospheric responses due to great geomagnetic storms i.e. Dst index < 350 nT that occurred during solar cycle 23 are presented. The GPS Total Electron Content (TEC) and ionosonde data over Southern and Northern Hemisphere mid-latitudes were used to study the ionospheric responses. A geomagnetic latitude region of ±30° to ±46° within a longitude sector of 15° to 40° was considered. Using a criteria of Dst < -350 nT, there were only four great storm periods (29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004) in solar cycle 23. Analysis has shown that ionospheric dynamics during these disturbed conditions could be due to a number of dynamic and electrodynamics processes in both Hemispheres. In some instances the ionosphere responds differently to the same storm condition in both Hemispheres. Physical mechanisms related to (but not limited to) composition changes and electric fields will be discussed.

  12. Geomagnetic response to IMF and solar wind over different latitudes

    NASA Astrophysics Data System (ADS)

    Aslam, A. M.; Tripathi, Sharad Chandra; Mansoori, Azad Ahmad; Waheed, Malik Abdul

    2016-07-01

    In this paper a study on the response of geomagnetic field characteristics to the solar wind variation during three solar cycles (SC 21, SC 22, SC 23) have been conducted in a long term scale. The difference in the response of two different latitudinal characteristic indices has been investigated. For the purpose we have considered the high latitude index AE and the mid-latitude aa index and both gives the knowledge about the perturbations in the geomagnetic field conditions. Eventually we can infer the idea about the ionospheric current system changes in response to the solar wind conditions. The variation found in the AE and aa indices have been found to follow a 11 year cycle as similar to the sunspot variation. Also the correlation between the annual means of the solar wind parameters velocity V, magnetic filed B and the composite parameters BV and BV ^{2 } have been calculated . A difference was found between the correlations obtained for the AE and aa indices. We could also see that the difference in correlation follows a cyclic pattern i.e. the large difference is found during the solar maxima while a small difference is observed during the minima.

  13. Dynamical similarity of geomagnetic field reversals.

    PubMed

    Valet, Jean-Pierre; Fournier, Alexandre; Courtillot, Vincent; Herrero-Bervera, Emilio

    2012-10-01

    No consensus has been reached so far on the properties of the geomagnetic field during reversals or on the main features that might reveal its dynamics. A main characteristic of the reversing field is a large decrease in the axial dipole and the dominant role of non-dipole components. Other features strongly depend on whether they are derived from sedimentary or volcanic records. Only thermal remanent magnetization of lava flows can capture faithful records of a rapidly varying non-dipole field, but, because of episodic volcanic activity, sequences of overlying flows yield incomplete records. Here we show that the ten most detailed volcanic records of reversals can be matched in a very satisfactory way, under the assumption of a common duration, revealing common dynamical characteristics. We infer that the reversal process has remained unchanged, with the same time constants and durations, at least since 180 million years ago. We propose that the reversing field is characterized by three successive phases: a precursory event, a 180° polarity switch and a rebound. The first and third phases reflect the emergence of the non-dipole field with large-amplitude secular variation. They are rarely both recorded at the same site owing to the rapidly changing field geometry and last for less than 2,500 years. The actual transit between the two polarities does not last longer than 1,000 years and might therefore result from mechanisms other than those governing normal secular variation. Such changes are too brief to be accurately recorded by most sediments. PMID:23038471

  14. Indian Institute of Geomagnetism: Progress in research

    NASA Astrophysics Data System (ADS)

    Progress and aspects is the study of the geomagnetic variations in the Indian region on quiet and disturbed days, equatorial electrojet field, electromagnetic induction in the earth, magnetic pulsations, aeronomy, radio scintillations, magnetosphere and solar wind, and solar-terrestrial relationships were reported.

  15. Power lines and the geomagnetic field

    SciTech Connect

    Liboff, A.R.; McLeod, B.R.

    1995-09-01

    The metric of prime interest in power line epidemiological studies has been AC magnetic intensity. To consider also possible geomagnetic involvement, the orientation of a long straight power line is examined relative to a uniform geomagnetic field (GMF) with dip angle {alpha}. An expression is derived for the component of the total GMF that is parallel, at an elevation {beta}, to the circular magnetic field that surrounds the line. This component is a function of the angles {alpha} and {beta}, the total geomagnetic intensity B{sub T}, and the angle {theta} between the axis of the power line and magnetic north. Plotting these geomagnetic parameters for known leukemia residences allows one to test for possible ion cyclotron resonance or other GMF interactions. This approach, in principle, is an easy addition to existing or planned studies, because residential access is not required to obtain local values for {alpha}, {beta}, {theta}, and B{sub T}. The authors recommend including these parameters in the design of epidemiological studies examining power line fields and childhood leukemia.

  16. The association between space weather conditions and emergency hospital admissions for myocardial infarction during different stages of solar activity

    NASA Astrophysics Data System (ADS)

    Vencloviene, J.; Antanaitiene, J.; Babarskiene, R.

    2016-11-01

    A number of studies have established the effects of space weather on the human cardio-vascular system. We investigated whether geomagnetic storms (GS), solar proton events (SPEs), and X-class solar flare affect the risk of emergency hospitalization for acute myocardial infarction (MI) separately during declining (2004-2006) and rising (2010-2012) phases of solar activity. The data on hospital admissions for MI were obtained from the computer database of Lithuanian University of Health sciences from January 1, 2004 to December 31, 2012. We evaluated the associations between space weather conditions and the daily number of emergency admissions for MI by Poisson regression, controlling for seasonal variation and weekdays. During 2004-2006, an increase in the risk of hospital admission for MI was observed on days of the daily mean proton >10 MeV flux >100 pfu (by 63%, p<0.001) and on days of GS concomitant with SPE, 1-2 days following these events, and on days of SPE occurring 1-2 days before GS concomitant with SPE (by 26%, p=0.019). During 2010-2012, an increase in the risk of hospital admission for MI was observed on days of the daily mean proton >10 MeV flux >100 pfu (by 52%, p=0.015) and on days of GS and 1-2 days after GS (by 17%, p=0.024). These findings suggest that the impact of hazardous space weather conditions on human health depends of the strength of space storm during the investigated period.

  17. Geomagnetic storms link to the mortality rate in the Smolyan region for the period 1988--2009

    NASA Astrophysics Data System (ADS)

    Simeonova, Siyka G. 1; Georgieva, Radostina C. 2; Dimitrova, Boryana H. 2; Slavcheva, Radka G. 2; Kerimova, Bojena P. 2; Georgiev, Tsvetan B. 34

    We present correlations and trends of 10 parameters of annual mortality rate (1 to common mortality rate, 5 to cardiovascular reasons and 4 to "accidental" reasons (car accidents, suicides, infections)) with respect to 6 parameters of annual solar and geomagnetic activity (Wolf index, number of geomagnetic storms, duration of the storms, amplitude of the storms). During the period of observation, characterized by a 3-4-fold decrease of the mean geomagnetic activity (in terms of the number and the duration of the storms) and with a strong variations of the amplitude of the storms (about an almost constant mean values for the period), there is a 1.3-fold decrease in the urban population, a 1.5-fold increase of the common mortality rate, a 1.8-fold increase of the cardiovascular mortality rate and a 1.1-fold decrease of the "accidental" mortality rates. During the years 2003-2005 we observe about 2-fold temporary increase in the storm amplitudes. During the years 2007-2008, characterized by extremely low geomagnetic activity, we observe a surprising temporary increase of the common and the cardiovascular mortality rates 1.1 and 1.3-fold, respectively (Figures 1-4). We point out 3 main results. (1) The available data shows notable increase in the mortality rates while there is generally a decrease of the solar or geomagnetic activity during the studied period (Figures 5-9). We explain this anti-correlation with the domination of the increasing mortality rates as an effect of the advance in the mean age of the population (due to immigration of young people and decrease of new-borns), hiding an eventual display of the solar and geomagnetic influence on the mortality rates. Using this data we can not reveal influence of the long-time (10-20 years) change of the average solar and geomagnetic activity on the mortality rate. (2) Excluding the unusual years 2007 and 2008, we establish that with respect to the years with low geomagnetic activity (1993, 1995, 1996, 1999), in

  18. Incorporation of geomagnetic data and services into EPOS infrastructure

    NASA Astrophysics Data System (ADS)

    Hejda, Pavel; Chambodut, Aude; Curto, Juan-Jose; Flower, Simon; Kozlovskaya, Elena; Kubašta, Petr; Matzka, Jürgen; Tanskanen, Eija; Thomson, Alan

    2016-04-01

    Monitoring of the geomagnetic field has a long history across Europe that dates back to 1830', and is currently experiencing an increased interest within Earth observation and space weather monitoring. Our goals within EPOS-IP are to consolidate the community, modernise data archival and distribution formats for existing services and create new services for magnetotelluric data and geomagnetic models. Specific objectives are: • Enhance existing services providing geomagnetic data (INTERMAGNET- INTErnational Real-time MAGnetic observatory NETwork; World Data Centre for Geomagnetism; IMAGE- International Monitor for Auroral Geomagnetic Effects) and existing services providing geomagnetic indices (ISGI - International Service of Geomagnetic Indices). • Develop and enhance the geomagnetic community's metadata systems by creating a metadata database, filling it and putting in place processes to ensure that it is kept up to date in the future. • Develop and build access to magnetotelluric (MT) data including transfer functions and time series data from temporary, portable MT-arrays in Europe, as well as to lithospheric conductivity models derived from TM-data. • Develop common web and database access points to global and regional geomagnetic field and conductivity models. • Establish links from the geomagnetic data services, products and models to the Integrated Core Services. The immediate task in the current period is to identify data models of existing services, modify them and integrate into a common model of Geomagnetic Thematic Core Services.

  19. Solar daily variation at geomagnetic observatories in Pakistan

    NASA Astrophysics Data System (ADS)

    Rahim, Zain; Kumbher, Abdul Salam

    2016-03-01

    A study of solar daily variation is performed using the famous Chapman-Miller method for solar cycles 22 & 23 (1986-2007). The objective is to study the characteristics of Sq variation at Pakistani geomagnetic observatories using solar harmonics and a more traditional five quietest day's method. The data recorded at the Karachi geomagnetic observatory for SC 22 and 23 and data sets from other Pakistani geomagnetic observatories; Sonmiani, Quetta and Islamabad are analyzed for H, D and Z components of the geomagnetic field. Except for the D and Z components at Karachi and Sonmiani and H component at Islamabad, the two solar daily variations correlated well with each other. Also, the synthesized daily variation from the solar harmonics of H, D and Z components explained the equivalent Sq current system reasonably well for all seasons. For H component, the first solar harmonic (s1) obtained from spherical harmonic analysis of the data, appeared as the largest harmonic with no significant changes for the seasonal division of data. However, for D and Z components, amplitudes are comparable, but undergo distinct variations. s1 for H and D components increases with magnetic activity while for Z component it is the largest for the medium phase of magnetic activity. With the sunspot number division of data, the weighted mean of the Wolf ratio of all three components is in good agreement with the previous studies. The synthesized solar daily variation for D component, S(D), at Karachi, Sonmiani, Quetta and Islamabad did not show any signs of winter anomaly for the period studied. However, S(D) variation at Karachi during winter season showed morning minimum followed by a maximum at local noon and another minimum in the afternoon. We suggest this could be the effects of Equatorial Ionospheric Anomaly (EIA) observable at the Karachi observatory only during the winter season. Similarly, much disturbed in equinoctial and summer months, S(Z) illustrated an unwavering daily

  20. New potentially active pyrazinamide derivatives synthesized under microwave conditions.

    PubMed

    Jandourek, Ondrej; Dolezal, Martin; Kunes, Jiri; Kubicek, Vladimir; Paterova, Pavla; Pesko, Matus; Buchta, Vladimir; Kralova, Katarina; Zitko, Jan

    2014-01-01

    A series of 18 N-alkyl substituted 3-aminopyrazine-2-carboxamides was prepared in this work according to previously experimentally set and proven conditions using microwave assisted synthesis methodology. This approach for the aminodehalogenation reaction was chosen due to higher yields and shorter reaction times compared to organic reactions with conventional heating. Antimycobacterial, antibacterial, antifungal and photosynthetic electron transport (PET) inhibiting in vitro activities of these compounds were investigated. Experiments for the determination of lipophilicity were also performed. Only a small number of substances with alicyclic side chain showed activity against fungi which was the same or higher than standards and the biological efficacy of the compounds increased with rising lipophilicity. Nine pyrazinamide derivatives also inhibited PET in spinach chloroplasts and the IC50 values of these compounds varied in the range from 14.3 to 1590.0 μmol/L. The inhibitory activity was connected not only with the lipophilicity, but also with the presence of secondary amine fragment bounded to the pyrazine ring. Structure-activity relationships are discussed as well. PMID:24995919

  1. What do we mean by accuracy in geomagnetic measurements?

    USGS Publications Warehouse

    Green, A.W.

    1990-01-01

    High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

  2. Geomagnetic avtivity triggered by interplanetary shocks: The shock impact angle as a controlling factor

    NASA Astrophysics Data System (ADS)

    Oliveira, D. M.; Raeder, J.; Tsurutani, B.; Gjerloev, J. W.

    2015-12-01

    We study the influence of interplanetary (IP) shock impact angles in the shock geoeffectiveness focusing on simulations and observations. In our simulations, we use OpenGGCM simulations to study the magnetospheric and ionospheric responses to shock impacts. Three cases are presented here: two inclined shocks, with 3.7 and 7.4 Mach numbers, and a frontal shock, whose shock normal is along the Sun-Earth line, with Mach number of 7.4. We find that, in the two inclined cases, due to the north-south asymmetry, the magnetotail is deflected southward, leading to a mild compression. The geomagnetic activity observed in the nightside ionosphere is then weak. On the other hand, in the head-on case, the magnetotail is compressed from both sides symmetrically. This compression triggers a substorm. By comparing the strong inclined shock and the frontal shock, we find that, despite the inclined shock having a larger Mach number, the frontal shock leads to a larger geomagnetic response in the nightside ionosphere. As a result, we conclude that IP shocks with similar upstream conditions, such as Mach number, can have different geoeffectiveness, depending on their shock normal orientation. In our observational study, we present a survey of IP shocks at 1 AU using Wind and ACE satellite data from Jan 1995 to Dec 2013 to study the same shock-related effects. A shock list covering one and a half solar cycle is compiled. We use data from SuperMAG, a large chain with more than 300 geomagnetic stations, to study geoeffectiveness triggered by IP shocks. The SuperMAG SML index (enhanced AL index), is used to quantify substorm strength. The jumps of the SML index triggered by shock impacts is investigated in terms of shock orientation and speed. We find that, in general, strong and almost frontal shocks are more geoeffective than inclined shocks with low speed. The highest correlations (R = 0.78) occurs for fixed shock speed and varying the shock impact angle. We attribute this result

  3. Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

    NASA Astrophysics Data System (ADS)

    Namgaladze, A. A.; Förster, M.; Yurik, R. Y.

    2000-04-01

    Current theories of F-layer storms are discussed using numerical simulations with the Upper Atmosphere Model, a global self-consistent, time dependent numerical model of the thermosphere-ionosphere-plasmasphere-magnetosphere system including electrodynamical coupling effects. A case study of a moderate geomagnetic storm at low solar activity during the northern winter solstice exemplifies the complex storm phenomena. The study focuses on positive ionospheric storm effects in relation to thermospheric disturbances in general and thermospheric composition changes in particular. It investigates the dynamical effects of both neutral meridional winds and electric fields caused by the disturbance dynamo effect. The penetration of short-time electric fields of magnetospheric origin during storm intensification phases is shown for the first time in this model study. Comparisons of the calculated thermospheric composition changes with satellite observations of AE-C and ESRO-4 during storm time show a good agreement. The empirical MSISE90 model, however, is less consistent with the simulations. It does not show the equatorward propagation of the disturbances and predicts that they have a gentler latitudinal gradient. Both theoretical and experimental data reveal that although the ratio of [O]/[N2] at high latitudes decreases significantly during the magnetic storm compared with the quiet time level, at mid to low latitudes it does not increase (at fixed altitudes) above the quiet reference level. Meanwhile, the ionospheric storm is positive there. We conclude that the positive phase of the ionospheric storm is mainly due to uplifting of ionospheric F2-region plasma at mid latitudes and its equatorward movement at low latitudes along geomagnetic field lines caused by large-scale neutral wind circulation and the passage of travelling atmospheric disturbances (TADs). The calculated zonal electric field disturbances also help to create the positive ionospheric disturbances both

  4. The use of various interplanetary scintillation indices within geomagnetic forecasts

    NASA Astrophysics Data System (ADS)

    Lucek, E. A.; Clark, T. D. G.; Moore, V.

    1996-02-01

    Interplanetary scintillation (IPS), the twinkling of small angular diameter radio sources, is caused by the interaction of the signal with small-scale plasma irregularities in the solar wind. The technique may be used to sense remotely the near-Earth heliosphere and observations of a sufficiently large number of sources may be used to track large-scale disturbances as they propagate from close to the Sun to the Earth. Therefore, such observations have potential for use within geomagnetic forecasts. We use daily data from the Mullard Radio Astronomy Observatory, made available through the World Data Centre, to test the success of geomagnetic forecasts based on IPS observations. The approach discussed here was based on the reduction of the information in a map to a single number or series of numbers. The advantages of an index of this nature are that it may be produced routinely and that it could ideally forecast both the occurrence and intensity of geomagnetic activity. We start from an index that has already been described in the literature, INDEX35. On the basis of visual examination of the data in a full skymap format modifications were made to the way in which the index was calculated. It was hoped that these would lead to an improvement in its forecasting ability. Here we assess the forecasting potential of the index using the value of the correlation coefficient between daily Ap and the IPS index, with IPS leading by 1 day. We also compare the forecast based on the IPS index with forecasts of Ap currently released by the Space Environment Services Center (SESC). Although we find that the maximum improvement achieved is small, and does not represent a significant advance in forecasting ability, the IPS forecasts at this phase of the solar cycle are of a similar quality to those made by SESC.

  5. Infrared response of the thermosphere-ionosphere system to geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Thayer, J. P.; Mlynczak, M. G.; Hunt, L. A.; Russell, J. M., III

    2015-12-01

    For 14 years the SABER instrument on the NASA TIMED satellite has been observing the radiative cooling of the thermosphere-ionosphere system associated with infrared emission by nitric oxide (NO) and carbon dioxide (CO2). From these observations a very clear picture of fundamental processes that control the thermal structure above 100 km has emerged. The radiative cooling is modulated by variations in solar UV irradiance and geomagnetic effects. A pronounced solar cycle variation in both NO and CO2 cooling is observed, and CO2 cooling dominates during solar minimum. Radiative cooling in the current maximum peaked in December 2014, nine months after the sunspot peak. On average, solar ultraviolet irradiance provides about 70% of the energy that results in cooling by NO and the remaining 30% arises from geomagnetic processes. The relative roles of irradiance and geomagnetism vary strongly over a solar cycle. Of particular interest are the large, short-term increases in radiative cooling associated with intense geomagnetic storms. The large energy deposition heats the atmosphere and the infrared cooling increases non-linearly, helping the atmosphere to shed the storm energy and rapidly return to pre-storm conditions. This "natural thermostat" effect of infrared radiation will be shown in detail in this talk, as a function of latitude and altitude for a number of different geomagnetic storms. The relative roles of radiative cooling by NO and CO2 will also be investigated, to see if there is any storm-dependent preference. Finally, the sensitivity of the NO cooling to geomagnetic processes suggests that near real time observations of NO emission may serve as a forecasting tool for space weather. Increases in NO infrared emissions are associated with energy deposition and heating of the atmosphere. Observations of NO emission may then identify regions in which atmospheric drag is increasing, and thus may be a tool for now casting of drag for space operations.

  6. Comment on 'Geomagnetic activity associated with earth passage of interplanetary shock disturbances and coronal mass ejections' by J. T. Gosling, D. J. McComas, J. L. Philips, and S. J. Bame

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1993-01-01

    It is contended that statistical data do not support the claim of Gosling et al. (1991) to the effect that the initial speed of a solar wind driver gas close to the sun appears to be the most crucial factor in determining if an earthward direct event will be effective in exciting a large geomagnetic disturbance. It is argued that the time intervals are much too large to observe the storm-time B sub Z dependence. Gosling et al. reply that this comment is based on a serious misunderstanding of their conclusions.

  7. Effects of atmospheric conditions on ice nucleation activity of Pseudomonas

    NASA Astrophysics Data System (ADS)

    Attard, E.; Yang, H.; Delort, A.-M.; Amato, P.; Pöschl, U.; Glaux, C.; Koop, T.; Morris, C. E.

    2012-11-01

    Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i) acidic pH (ii) NO2 and O3 exposure and (iii) UV-A exposure on the ice nucleation activity (INA) of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 °C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.

  8. Effects of atmospheric conditions on ice nucleation activity of Pseudomonas

    NASA Astrophysics Data System (ADS)

    Attard, E.; Yang, H.; Delort, A.-M.; Amato, P.; Pöschl, U.; Glaux, C.; Koop, T.; Morris, C. E.

    2012-04-01

    Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i) acidic pH (ii) NO2 and O3 exposure and (iii) UV-A exposure on the ice nucleation activity (INA) of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 °C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.

  9. Magnetic clouds, geomagnetic disturbances, and cosmic ray decreases

    NASA Technical Reports Server (NTRS)

    Zhang, G.; Burlaga, L. F.

    1988-01-01

    Nineteen magnetic clouds are identified in the years from 1978 through 1982 and studied using superposed epoch analysis. The magnetic-field intensity, proton density and proton temperature are enhanced ahead of magnetic clouds that are preceded by shock, while strong magnetic-field intensity and low proton temperature are observed within the clouds. A relatively large (about 2.5 percent) decrease in cosmic-ray intensity is associated with magnetic clouds that are preceded by a shock, perhaps caused by the turbulent sheath behind an interplanetary shock ahead of the magnetic cloud, whereas only a small (0.5 percent) decrease in intensity is associated with the magnetic cloud itself. Magnetic clouds can produce geomagnetic activity with a decrease in Dst index of the order 100 gamma. The magnitude of the change in the Dst index for the case when southward fields arrive first is comparable to that for the case when northward fields arrive first, and the phase is such that geomagnetic activity is associated with southward fields.

  10. Fine structure of the 2003 geomagnetic jerk near China

    NASA Astrophysics Data System (ADS)

    Ou, J.; Du, A.

    2015-12-01

    The 2003 jerk has an abrupt change in the geomagnetic secular variation (SV), and was recognized as a local phenomenon of internal origin from the satellite observations (Olsen and Mandea, 2007). Notable strength of the 2003 jerk is located near China. The temporal and spatial features at this area are important to resolve the Earth's core fluid flow dynamics at local scale (e.g. Wardinski et al., 2008). We investigate the temporal-spatial development of the 2003 jerk in more detail near China with the ground-based observations and CHAOS-3 core field model. We select the data in the international geomagnetic quiet days to calculate the monthly means. In order to reduce the influence of the external field, we adopt a function comprising the terms associated with the indices of the geomagnetic activity, and the terms of the periodic signals on the observatory monthly means data (Stewart and Whaler, 1992). We then use an empirical AR-2 model to represent the internal field signals in the observatory data. The extreme detection is applied to identify the jerk in the SV time series. The onset time and the strength of the 2003 jerk are obtained through the detection for geomagnetic field component, X, Y and Z. The maximum of the strength of the 2003 jerk is located under the Indian mainland. The onset time of this jerk propagates approximately southeastward. Two jerks in 2001 and 2003 for the Z component are further compared and they are confirmed as independent processes. We suggest the jerk in 2001 identical to the well known 1999 jerk in Europe (Mandea et al., 2000). Our results reveal the fine structures of the 2003 jerk that corroborate the conclusions in previous studies. The larger scale time-spatial structure given by the AR-2 model constructed from ground observatory data (monthly values) is consistent with the results from the CHAOS-3 model. This structure can be applied for further inversion of the local core surface fluid flow motions.

  11. A Combined Solar and Geomagnetic Index for Thermospheric Climate

    NASA Technical Reports Server (NTRS)

    Hunt, Linda; Mlynczak, Marty

    2015-01-01

    Infrared radiation from nitric oxide (NO) at 5.3 Â is a primary mechanism by which the thermosphere cools to space. The SABER instrument on the NASA TIMED satellite has been measuring thermospheric cooling by NO for over 13 years. Physically, changes in NO emission are due to changes in temperature, atomic oxygen, and the NO density. These physical changes however are driven by changes in solar irradiance and changes in geomagnetic conditions. We show that the SABER time series of globally integrated infrared power (Watts) radiated by NO can be replicated accurately by a multiple linear regression fit using the F10.7, Ap, and Dst indices. This fit enables several fundamental properties of NO cooling to be determined as well as their variability with time, permitting reconstruction of the NO power time series back nearly 70 years with extant databases of these indices. The relative roles of solar ultraviolet and geomagnetic processes in determining the NO cooling are derived and shown to be solar cycle dependent. This reconstruction provides a long-term time series of an integral radiative constraint on thermospheric climate that can be used to test climate models.

  12. Ionospheric Response During Four Intense Geomagnetic Storms: Similarities and Differences

    NASA Astrophysics Data System (ADS)

    Mannucci, A. J.; Tsurutani, B. T.; Crowley, G.; Verkhoglyadova, O. P.

    2007-05-01

    Large magnitude and hemispheric-scale increases in ionospheric plasma content are observed for daytime local times during intense geomagnetic storms. Ionospheric increases during the main phase of geomagnetic storms were identified many years ago and categorized as the "positive phase" ionospheric response. This talk will explore what we can learn using satellite data and distributed ground-based measurements, to understand the geoeffective processes at work in creating the positive phase for intense storms. The importance of electric fields penetrating to low latitudes on the dayside has received a great deal of attention recently, and is leading to revised theoretical and modeling constructs to account for the observations in a quantitative manner. We will present ground and space-based Global Positioning System (GPS) electron content data for four storms and analyze the data in light of the upstream conditions with a common epoch analysis. Modeling studies of the storm-time ionospheric behavior will be shown, using the ASPEN-TIMEGCM fully-coupled thermosphere- ionosphere (T-I) model with low-latitude electrodynamics. The ASPEN-TIMEGCM model contains storm-time effects such as winds and the resulting dynamo electric fields, but penetration E-fields including shielding are not currently included. The model runs are driven by carefully reconstructed high latitude time-dependent drivers based in part on the AMIE high latitude electrodynamics model. The time history of a modeled storm will be compared with observations. We will highlight outstanding science questions that are revealed in this study.

  13. Geomagnetically induced currents in Uruguay: Sensitivity to modelling parameters

    NASA Astrophysics Data System (ADS)

    Caraballo, R.

    2016-11-01

    According to the traditional wisdom, geomagnetically induced currents (GIC) should occur rarely at mid-to-low latitudes, but in the last decades a growing number of reports have addressed their effects on high-voltage (HV) power grids at mid-to-low latitudes. The growing trend to interconnect national power grids to meet regional integration objectives, may lead to an increase in the size of the present energy transmission networks to form a sort of super-grid at continental scale. Such a broad and heterogeneous super-grid can be exposed to the effects of large GIC if appropriate mitigation actions are not taken into consideration. In the present study, we present GIC estimates for the Uruguayan HV power grid during severe magnetic storm conditions. The GIC intensities are strongly dependent on the rate of variation of the geomagnetic field, conductivity of the ground, power grid resistances and configuration. Calculated GIC are analysed as functions of these parameters. The results show a reasonable agreement with measured data in Brazil and Argentina, thus confirming the reliability of the model. The expansion of the grid leads to a strong increase in GIC intensities in almost all substations. The power grid response to changes in ground conductivity and resistances shows similar results in a minor extent. This leads us to consider GIC as a non-negligible phenomenon in South America. Consequently, GIC must be taken into account in mid-to-low latitude power grids as well.

  14. Driving Plasmaspheric Electron Density Simulations During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    De Pascuale, S.; Kletzing, C.; Jordanova, V.; Goldstein, J.; Wygant, J. R.; Thaller, S. A.

    2015-12-01

    We test global convection electric field models driving plasmaspheric electron density simulations (RAM-CPL) during geomagnetic storms with in situ measurements provided by the Van Allen Probes (RBSP). RAM-CPL is the cold plasma component of the ring-current atmosphere interactions suite (RAM-SCB) and describes the evolution of plasma density in the magnetic equatorial plane near Earth. Geomagnetic events observed by the RBSP satellites in different magnetic local time (MLT) sectors enable a comparison of local asymmetries in the input electric field and output densities of these simulations. Using a fluid MHD approach, RAM-CPL reproduces core plasmaspheric densities (L<4) to less than 1 order of magnitude difference. Approximately 80% of plasmapause crossings, defined by a low-density threshold, are reproduced to within a mean radial difference of 0.6 L. RAM-CPL, in conjunction with a best-fit driver, can be used in other studies as an asset to predict density conditions in locations distant from RBSP orbits of interest.

  15. Gravitational dynamos and the low-frequency geomagnetic secular variation.

    PubMed

    Olson, P

    2007-12-18

    Self-sustaining numerical dynamos are used to infer the sources of low-frequency secular variation of the geomagnetic field. Gravitational dynamo models powered by compositional convection in an electrically conducting, rotating fluid shell exhibit several regimes of magnetic field behavior with an increasing Rayleigh number of the convection, including nearly steady dipoles, chaotic nonreversing dipoles, and chaotic reversing dipoles. The time average dipole strength and dipolarity of the magnetic field decrease, whereas the dipole variability, average dipole tilt angle, and frequency of polarity reversals increase with Rayleigh number. Chaotic gravitational dynamos have large-amplitude dipole secular variation with maximum power at frequencies corresponding to a few cycles per million years on Earth. Their external magnetic field structure, dipole statistics, low-frequency power spectra, and polarity reversal frequency are comparable to the geomagnetic field. The magnetic variability is driven by the Lorentz force and is characterized by an inverse correlation between dynamo magnetic and kinetic energy fluctuations. A constant energy dissipation theory accounts for this inverse energy correlation, which is shown to produce conditions favorable for dipole drift, polarity reversals, and excursions. PMID:18048345

  16. Natural variability of atmospheric temperatures and geomagnetic intensity over a wide range of time scales

    PubMed Central

    Pelletier, Jon D.

    2002-01-01

    The majority of numerical models in climatology and geomagnetism rely on deterministic finite-difference techniques and attempt to include as many empirical constraints on the many processes and boundary conditions applicable to their very complex systems. Despite their sophistication, many of these models are unable to reproduce basic aspects of climatic or geomagnetic dynamics. We show that a simple stochastic model, which treats the flux of heat energy in the atmosphere by convective instabilities with random advection and diffusive mixing, does a remarkable job at matching the observed power spectrum of historical and proxy records for atmospheric temperatures from time scales of one day to one million years (Myr). With this approach distinct changes in the power-spectral form can be associated with characteristic time scales of ocean mixing and radiative damping. Similarly, a simple model of the diffusion of magnetic intensity in Earth's core coupled with amplification and destruction of the local intensity can reproduce the observed 1/f noise behavior of Earth's geomagnetic intensity from time scales of 1 (Myr) to 100 yr. In addition, the statistics of the fluctuations in the polarity reversal rate from time scales of 1 Myr to 100 Myr are consistent with the hypothesis that reversals are the result of variations in 1/f noise geomagnetic intensity above a certain threshold, suggesting that reversals may be associated with internal fluctuations rather than changes in mantle thermal or magnetic boundary conditions. PMID:11875208

  17. Natural variability of atmospheric temperatures and geomagnetic intensity over a wide range of time scales.

    PubMed

    Pelletier, Jon D

    2002-02-19

    The majority of numerical models in climatology and geomagnetism rely on deterministic finite-difference techniques and attempt to include as many empirical constraints on the many processes and boundary conditions applicable to their very complex systems. Despite their sophistication, many of these models are unable to reproduce basic aspects of climatic or geomagnetic dynamics. We show that a simple stochastic model, which treats the flux of heat energy in the atmosphere by convective instabilities with random advection and diffusive mixing, does a remarkable job at matching the observed power spectrum of historical and proxy records for atmospheric temperatures from time scales of one day to one million years (Myr). With this approach distinct changes in the power-spectral form can be associated with characteristic time scales of ocean mixing and radiative damping. Similarly, a simple model of the diffusion of magnetic intensity in Earth's core coupled with amplification and destruction of the local intensity can reproduce the observed 1/f noise behavior of Earth's geomagnetic intensity from time scales of 1 (Myr) to 100 yr. In addition, the statistics of the fluctuations in the polarity reversal rate from time scales of 1 Myr to 100 Myr are consistent with the hypothesis that reversals are the result of variations in 1/f noise geomagnetic intensity above a certain threshold, suggesting that reversals may be associated with internal fluctuations rather than changes in mantle thermal or magnetic boundary conditions. PMID:11875208

  18. Spectral characteristics of geomagnetic field variations at low and equatorial latitudes

    USGS Publications Warehouse

    Campbell, W.H.

    1977-01-01

    Geomagnetic field spectra from eight standard observations at geomagnetic latitudes below 30?? were studied to determine the field characteristics unique to the equatorial region. Emphasis was placed upon those variations having periods between 5 min and 4 hr for a selection of magnetically quiet, average, and active days in 1965. The power spectral density at the equator was about ten times that the near 30?? latitude. The initial manifestation of the equatorial electrojet as evidenced by the east-west alignment of the horizontal field or the change in vertical amplitudes occurred below about 20?? latitude. Induced current effects upon the vertical component from which the Earth conductivity might be inferred could best be obtained at times and latitudes unaffected by the electrojet current. Values of about 1.6 ?? 103 mhos/m for an effective skin depth of 500-600 km were determined. The spectral amplitudes increased linearly with geomagnetic activity index, Ap. The spectral slope had a similar behavior at all latitudes. The slope changed systematically with Ap-index and showed a diurnal variation, centered on local noon, that changed form with geomagnetic activity.

  19. Why have geomagnetic storms been so weak during the recent solar minimum and the rising phase of cycle 24?

    NASA Astrophysics Data System (ADS)

    Kilpua, E. K. J.; Luhmann, J. G.; Jian, L. K.; Russell, C. T.; Li, Y.

    2014-01-01

    The minimum following solar cycle 23 was the deepest and longest since the dawn of the space age. In this paper we examine geomagnetic activity using Dst and AE indices, interplanetary magnetic field (IMF) and plasma conditions, and the properties and occurrence rate of interplanetary coronal mass ejections (ICMEs) during two periods around the last two solar minima and rising phases (Period 1: 1995-1999 and Period 2: 2006-2012). The data is obtained from the 1-h OMNI database. Geomagnetic activity was considerably weaker during Period 2 than during Period 1, in particular in terms of Dst. We show that the responses of AE and Dst depend on whether it is solar wind speed or the southward IMF component (BS) that controls the variations in solar wind driving electric field (EY). We conclude that weak Dst activity during Period 2 was primarily a consequence of weak BS and presumably further weakened due to low solar wind densities. In contrast, solar wind speed did not show significant differences between our two study periods and the high-speed solar wind during Period 2 maintained AE activity despite of weak BS. The weakness of BS during Period 2 was attributed in particular to the lack of strong and long-duration ICMEs. We show that for our study periods there was a clear annual north-south IMF asymmetry, which affected in particular the intense Dst activity. This implies that the annual amount of intense Dst activity may rather be determined by the coincidence of what magnetic structure the strong ICMEs encountering the Earth have than by the solar cycle size.

  20. Empirical Model of Subauroral Polarization Streams (SAPS) During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Landry, R. G.

    2015-12-01

    Subauroral Polarization Streams (SAPS) are important electromagnetic phenomena associated with geomagnetic storms that affect the inner magnetosphere and ionosphere. They are characterized by strong sunward plasma flows caused by poleward-directed electric fields in the region of the ionosphere equatorword of the auroral zone. To examine the effects subauroral electric fields have on ITM coupling and magnetospheric-ionospheric convection we are developing an empirical model of SAPS using data acquired by the Defense Meteorological Satellite Program (DMSP) spacecraft which have made decades of in-situ measurements of ionospheric ion drifts, composition, and precipitating auroral particles. These measurements are used to characterize the subauroral electric fields relative to the location of the auroral boundary at varying magnetic local times and magnetic activity levels. As a critical component of this model, we have developed a model of the nightside zero energy electron precipitation boundary equatorward of the auroral oval parameterized by AE and MLT, using boundary identifications derived from DMSP data. We will use this model to create a global subauroral potential model and perform a superposed epoch study of SAPS fields in relationship to the auroral boundary during selected geomagnetic storms as a function of storm phase. A global empirical model of SAPS electric fields of this kind is required to realistically model thermosphere-ionosphere coupling and inner-magnetospheric convection.

  1. Climate changes associated with high-amplitude Sq geomagnetic variations

    NASA Astrophysics Data System (ADS)

    Rabeh, Taha; Carvalho, Joao; Khalil, Ahmed; El-Aal, Esmat; El-Hemaly, Ibrahim

    2011-10-01

    When the solar irradiance propagates between the outer magnetospheric regions and the ionosphere, dynamic processes of the magnetosphere-ionosphere-thermosphere system are affected at the lower end of their paths by the interaction of radiation with the neutral troposphere. The main target of this work is to investigate the relationship between the diurnal magnetic field variations resulting from solar activities and the variation in the troposphere temperature. Meteorological and geomagnetic data acquired from different observatories located in Egypt, Portugal and Slovakia in a long-term and daily-term scales were analyzed. The long-term results show that there is a close relationship between the diurnal Sq magnetic field variations and the tropospheric temperature. The rate of temperature increase at mid-latitude areas is higher than at high-latitude. During the period of investigation, i