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Sample records for geomagnetic disturbance infradian

  1. Stress, geomagnetic disturbance, infradian and circadian sampling for circulating corticosterone and models of human depression?

    PubMed

    Olah, A; Jozsa, R; Csernus, V; Sandor, J; Muller, A; Zeman, M; Hoogerwerf, W; Cornélissen, G; Halberg, F

    2008-04-01

    While certain circadian hormonal changes are prominent, their predictable assessment requires a standardization of conditions of sampling. The 24-hour rhythm in circulating corticosterone of rodents, known since the 1950s, was studied as a presumed proxy for stress on 108 rats divided into 9 groups of 6 male and 9 groups of 6 female animals sampled every 4 hours for 24 hours. In a first stress study, the "no-rhythm" (zero-amplitude) assumption failed to be rejected at the 5% probability level in the two control groups and in 16 out of the 18 groups considered. A circadian rhythm could be detected with statistical significance, however, in three separate follow-up studies in the same laboratory, each on 168 rats kept on two antiphasic lighting regimens, with 4-hourly sampling for 7 or 14 days. In the first stress study, pooling of certain groups helped the detection and assessment of the circadian corticosterone rhythm. Without extrapolating to hormones other than corticosterone, which may shift more slowly or adjust differently and in response to different synchronizers, the three follow-up studies yielded uncertainty measures (95% confidence intervals) for the point estimate of its circadian period, of possible use in any future study as a reference standard. The happenstance of a magnetic disturbance at the start of two follow-up studies was associated with the detection of a circasemiseptan component, raising the question whether a geomagnetic disturbance could be considered as a "load". Far beyond the limitations of sample size, the methodological requirements for standardization in the experimental laboratory concerning designs of studies are considered in the context of models of depression. Lessons from nature's unforeseen geomagnetic contribution and from human studies are noted, all to support the advocacy, in the study of loads, of sampling schedules covering more than 24 hours. PMID:18515211

  2. Stress, Geomagnetic Disturbance, Infradian and Circadian Sampling for Circulating Corticosterone and Models of Human Depression?

    PubMed Central

    Olah, A.; Jozsa, R.; Csernus, V.; Sandor, J.; Muller, A.; Zeman, M.; Hoogerwerf, W.; Cornélissen, G.; Halberg, F.

    2008-01-01

    While certain circadian hormonal changes are prominent, their predictable assessment requires a standardization of conditions of sampling. The 24-hour rhythm in circulating corticosterone of rodents, known since the 1950s, was studied as a presumed proxy for stress on 108 rats divided into 9 groups of 6 male and 9 groups of 6 female animals sampled every 4 hours for 24 hours. In a first stress study, the “no-rhythm” (zero-amplitude) assumption failed to be rejected at the 5% probability level in the two control groups and in 16 out of the 18 groups considered. A circadian rhythm could be detected with statistical significance, however, in three separate follow-up studies in the same laboratory, each on 168 rats kept on two antiphasic lighting regimens, with 4-hourly sampling for 7 or 14 days. In the first stress study, pooling of certain groups helped the detection and assessment of the circadian corticosterone rhythm. Without extrapolating to hormones other than corticosterone, which may shift more slowly or adjust differently and in response to different synchronizers, the three follow-up studies yielded uncertainty measures (95% confidence intervals) for the point estimate of its circadian period, of possible use in any future study as a reference standard. The happenstance of a magnetic disturbance at the start of two follow-up studies was associated with the detection of a circasemiseptan component, raising the question whether a geomagnetic disturbance could be considered as a “load”. Far beyond the limitations of sample size, the methodological requirements for standardization in the experimental laboratory concerning designs of studies are considered in the context of models of depression. Lessons from nature's unforeseen geomagnetic contribution and from human studies are noted, all to support the advocacy, in the study of loads, of sampling schedules covering more than 24 hours. PMID:18515211

  3. 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.

  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. 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.

  6. 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.

  7. 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.

  8. Solar flares, flare particles and geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Ogawa, T.

    1986-03-01

    Geomagnetic disturbances related to solar-terrestrial events during the period June-September 1982 are described. The cause of these activities is investigated using solar phenomena and solar flare particles observed by the geostationary satellite GMS-2/SEM (Space Environment Monitor). It is noted that the geomagnetic disturbances in June were weak, two big geomagnetic storms occurred in September, and the largest storm, caused by a large flare, occurred on July 13-14. The July 13-14, 1972 storm is compared to the February 11-12, 1958 storm observed by Hakura and Nagai (1964, 1965) and the August 4-5, 1972 storm data of Hakura (1976). The July storm was characterized by a deep depression of the H-component caused by an abnormal expansion of the substorm-associated current system in the auroral zone toward the Far East and was short-lived.

  9. Disturbances in the US electric grid associated with geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Schrijver, Carolus J.; Mitchell, Sarah D.

    2013-05-01

    Large solar explosions are responsible for space weather that can impact technological infrastructure on and around Earth. Here, we apply a retrospective cohort exposure analysis to quantify the impacts of geomagnetic activity on the US electric power grid for the period from 1992 through 2010. We find, with more than 3σ significance, that approximately 4% of the disturbances in the US power grid reported to the US Department of Energy are attributable to strong geomagnetic activity and its associated geomagnetically induced currents.

  10. Geomagnetic disturbance and the orientation of nocturnally migrating birds.

    PubMed

    Moore, F R

    1977-05-01

    Free-flying passerine migrants respond to natural fluctuations in the earth's magnetic field. The variability in flight directions of nocturnal migrants is significantly correlated with increasing geomagnetic disturbance as measured by both the K index and various components of the earth's magnetic field. The results indicate that such disturbances influence the orientation of free-flying migrants, but the evidence is not sufficient to show that geomagnetism is a cue in their orientation system. PMID:854743

  11. Geomagnetic disturbances imprints in ground and satellite altitude observatories

    NASA Astrophysics Data System (ADS)

    Yahiat, Yasmina; Lamara, Souad; Zaourar, Naima; Hamoudi, Mohamed

    2016-04-01

    The temporal evolution of the geomagnetic field and its variations have been repeatedly studied from both ground observatories and near-earth orbiting platforms. With the advent of the space ageand the launches of geomagnetic low altitude orbits satellites, a global coverage has been achieved. Since Magsat mission, more satellites were put into orbit and some of them are still collecting data enhancing the spatial and temporal descriptions of the field. Our study uses new data gathered by the latest SWARM satellite mission launched on November, 22nd 2013. It consists of a constellation of three identical satellites carrying on board high resolution and accuracy scientific equipment. Data from this constellation will allow better understanding the multiscale behavior of the geomagnetic field. Our goal is to analyze and interpret the geomagnetic data collected by this Swarm mission, for a given period and try to separate the external disturbances from internal contributions. We consider in the study the variation of the horizontal component H, for different virtual geomagnetic observatories at the satellite altitude. The analysis of data by Swarm orbital segments shows clearly the external disturbances of the magnetic field like that occurring on 27th of August 2014. This perturbation is shown on geomagnetic indexes and is related to a coronal mass ejection (CME). These results from virtual observatories are confirmed, by the equivalent analysis using ground observatories data for the same geographic positions and same epochs. Key words: Geomagnetic field, external field, geomagnetic index, SWARM mission, virtual observatories.

  12. 78 FR 30747 - Reliability Standards for Geomagnetic Disturbances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-23

    ... Reliability Corporation (NERC), the Commission-certified Electric Reliability Organization, to submit to the... Commission directs the North American Electric Reliability Corporation (NERC), the Commission-certified... Report: Effects of Geomagnetic Disturbances on the Bulk Power System at ii (February 2012) (NERC...

  13. 77 FR 22312 - Geomagnetic Disturbances to the Bulk-Power System; Notice of Technical Conference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-13

    ... Energy Regulatory Commission Geomagnetic Disturbances to the Bulk-Power System; Notice of Technical... Conference on Geomagnetic Disturbances to the Bulk-Power System on Monday, April 30, 2012, from 11 a.m. to 4... issues related to reliability of the Bulk-Power System as affected by geomagnetic disturbances....

  14. Power grid disturbances and polar cap index during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Stauning, Peter

    2013-06-01

    The strong geomagnetic storm in the evening of 30 October 2003 caused high-voltage power grid disturbances in Sweden that expanded to produce hour-long power line outage in Malmö located in the southern part of the country. This was not a unique situation. The geomagnetic storm on 13 March 1989 caused extensive disruptions of high-voltage power circuits especially in the Province of Quebec, Canada, but also to a lesser degree in Scandinavia. Similar events have occurred earlier, among others, during the great storms of 13-14 July 1982 and 8-9 February 1986. These high-voltage power grid disturbances were related to impulsive magnetic variations accompanying extraordinarily intense substorm events. The events were preceded by lengthy intervals of unusually high values of the Polar Cap (PC) index caused by enhanced transpolar ionospheric convection. The transpolar convection transports magnetic flux from the dayside to nightside which causes equatorward displacements of the region of auroral activity enabling the substorms to hit vital power grids. During the 30 October 2003 event the intense solar proton radiation disabled the ACE satellite observations widely used to provide forecast of magnetic storm events. Hence in this case the alarmingly high PC index could provide useful warning of the storm as a back-up of the missing ACE-based forecast. In further cases, monitoring the PC index level could provide supplementary storm warnings to the benefit of power grid operators.

  15. Anomalous phenomena on HF radio paths during geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Blagoveshchenskii, D. V.

    2016-07-01

    We analyze ionospheric oblique sounding data on three high-latitude and one high-latitude-midlatitude HF radio paths for February 15 and 16, 2014, when two substorms and one magnetic storm occurred. We investigate cases of anomalous propagation of signals: their reflection from sporadic layer Es, lateral reflections, type "M" or "N" modes, the presence of traveling ionospheric disturbances, and the diffusivity of signals and triplets. The most significant results are the following. In geomagnetically undisturbed times, sporadic Es-layers with reduced maximum observed frequencies (MOF Es) on three high-latitude paths were observed in both days. The values of MOF Es during disturbances are large, which leads to the screening of other oblique sounding signals reflected from the ionosphere. On all four paths, the most frequently traveling ionospheric disturbances due to the terminator were observed in quiet hours from 03:00 to 15:00 UT on the first day and from 06:00 to 13:00 UT on the second day of the experiment. In addition, both the sunset terminator and the magnetic storm on the high-latitude-mid-latitude path were found to generate traveling ionospheric disturbances jointly. No such phenomenon was found on high-latitude paths.

  16. Coseismic ionospheric and geomagnetic disturbances caused by great earthquakes

    NASA Astrophysics Data System (ADS)

    Hao, Yongqiang; Zhang, Donghe; Xiao, Zuo

    2016-04-01

    Despite primary energy disturbances from the Sun, oscillations of the Earth surface due to a large earthquake will couple with the atmosphere and therefore the ionosphere, then the so-called coseismic ionospheric disturbances (CIDs) can be detected in the ionosphere. Using a combination of techniques, total electron content, HF Doppler, and ground magnetometer, a new time-sequence of such effects propagation were developed on observational basis and ideas on explanation provided. In the cases of 2008 Wenchuan and 2011 Tohoku earthquakes, infrasonic waves accompanying the propagation of seismic Rayleigh waves were observed in the ionosphere by all the three kinds of techniques. This is the very first report to present CIDs recorded by different techniques at co-located sites and profiled with regard to changes of both ionospheric plasma and current (geomagnetic field) simultaneously. Comparison between the oceanic (2011 Tohoku) and inland (2008 Wenchuan) earthquakes revealed that the main directional lobe of latter case is more distinct which is perpendicular to the direction of the fault rupture. We argue that the different fault slip (inland or submarine) may affect the way of couplings of lithosphere with atmosphere. References Zhao, B., and Y. Hao (2015), Ionospheric and geomagnetic disturbances caused by the 2008 Wenchuan earthquake: A revisit, J. Geophys. Res. Space Physics, 120, doi:10.1002/2015JA021035. Hao, Y. Q., Z. Xiao, and D. H. Zhang (2013), Teleseismic magnetic effects (TMDs) of 2011 Tohoku earthquake, J. Geophys. Res. Space Physics, 118, 3914-3923, doi:10.1002/jgra.50326. Hao, Y. Q., Z. Xiao, and D. H. Zhang (2012), Multi-instrument observation on co-seismic ionospheric effects after great Tohoku earthquake, J. Geophys. Res., 117, A02305, doi:10.1029/2011JA017036.

  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. Coronal holes, solar wind streams, and recurrent geomagnetic disturbances - 1973-1976

    NASA Technical Reports Server (NTRS)

    Sheeley, N. R., Jr.; Harvey, J. W.; Feldman, W. C.

    1976-01-01

    Observations of coronal holes, solar-wind streams, and geomagnetic disturbances during 1973-1976 are compared in a 27-day pictorial format which shows their long-term evolution. The results leave little doubt that coronal holes are related to the high-speed streams and their associated recurrent geomagnetic disturbances. In particular, these observations strongly support the hypothesis that coronal holes are the solar origin of the high-speed streams observed in the solar wind near the ecliptic plane.

  19. 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.

  20. The disturbances of ionospheric Total Electron Content during great geomagnetic storm above Iraq

    NASA Astrophysics Data System (ADS)

    Al-Ubaidi, Najat

    2016-07-01

    Several efforts have been made to study the behavior of Total Electron Content (TEC) with many types of geomagnetic storms; the purpose of this research is to study the disturbances of the ionosphere through the TEC parameter during great geomagnetic storm. TEC data selected for year 2003 (descending solar cycle 23), as available from (www.ngdc.noaa.gov/stp/IONO/USTEC/) for Iraq region (longitude 27-54 degree East, latitude 27-42 degree North) during great geomagnetic storm for 28-30 October 2003. To find out the type of geomagnetic storms the Disturbance storm time (Dst) index was selected for the days selected from Kyoto/Japan website. From data analysis, it is found that in general, there is a good proportionality between disturbance storm time index (Dst) and the total electron contents, the values of TEC in daytime greater than night time, but there is anomaly when the storm continued for several hours from the day.

  1. 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.

  2. 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

  3. Extreme geomagnetic disturbances due to shocks within CMEs

    NASA Astrophysics Data System (ADS)

    Lugaz, N.; Farrugia, C. J.; Huang, C.-L.; Spence, H. E.

    2015-06-01

    We report on features of solar wind-magnetosphere coupling elicited by shocks propagating through coronal mass ejections (CMEs) by analyzing the intense geomagnetic storm of 6 August 1998. During this event, the dynamic pressure enhancement at the shock combined with a simultaneous increase in the southward component of the magnetic field resulted in a large earthward retreat of Earth's magnetopause, which remained close to geosynchronous orbit for more than 4 h. This occurred despite the fact that both shock and CME were weak and relatively slow. Another similar example of a weak shock inside a slow CME resulting in an intense geomagnetic storm is the 30 September 2012 event, which strongly depleted the outer radiation belt. We discuss the potential of shocks inside CMEs to cause large geomagnetic effects at Earth, including magnetopause shadowing.

  4. Traveling ionospheric disturbances observed at South African midlatitudes during the 29-31 October 2003 geomagnetically disturbed period

    NASA Astrophysics Data System (ADS)

    Katamzi, Zama T.; Habarulema, John Bosco

    2014-01-01

    This paper presents traveling ionospheric disturbances (TIDs) observations from GPS measurements over the South African region during the geomagnetically disturbed period of 29-31 October 2003. Two receiver arrays, which were along two distinct longitudinal sectors of about 18°-20° and 27°-28° were used in order to investigate the amplitude, periods and virtual propagation characteristics of the storm induced ionospheric disturbances. The study revealed a large sudden TEC increase on 28 October 2003, the day before the first of the two major storms studied here, that was recorded simultaneously by all the receivers used. This pre-storm enhancement was linked to an X-class solar flare, auroral/magnetospheric activities and vertical plasma drift, based on the behaviour of the geomagnetic storm and auroral indices as well as strong equatorial electrojet. Diurnal trends of the TEC and foF2 measurements revealed that the geomagnetic storm caused a negative ionospheric storm; these parameters were depleted between 29 and 31 October 2003. Large scale traveling ionospheric disturbances were observed on the days of the geomagnetic storms (29 and 31 October 2003), using line-of-sight vertical TEC (vTEC) measurements from individual satellites. Amplitude and dominant periods of these structures varied between 0.08-2.16 TECU, and 1.07-2.13 h respectively. The wave structures were observed to propagate towards the equator with velocities between 587.04 and 1635.09 m/s.

  5. Fractal and wavelet analysis evaluation of the mid latitude ionospheric disturbances associated with major geomagnetic storms

    NASA Astrophysics Data System (ADS)

    López-Montes, Rebeca; Pérez-Enríquez, Román; Araujo-Pradere, Eduardo A.; López Cruz-Abeyro, Jose Antonio

    2015-01-01

    Variations of the total electron content (TEC) of the ionosphere are mainly associated with major geomagnetic storms occurring with the arrival of coronal mass ejections (CMEs) to the Earth environment. The purpose of this paper is to show results of the analysis we made of the impact of all major geomagnetic storms (Dst < - 200 nT) on the ionosphere at mid latitudes, which have occurred since 2000. The analysis consists in the calculation of TEC of the ionosphere using data from several Mexican GPS stations, with the purpose of quantifying the impact into the ionosphere to these latitudes, through the variations in amplitude, Hurst index, that is roughness, and wavelet transform of the time series of TEC. Indeed, during the geomagnetic storms of April 7, 2000, July 16, 2000, October 30, 2003, November 20, 2003 and November 8, 2004, major ionospheric disturbances at mid latitudes took place with changes in amplitude of TEC going from 3.29 to 8.82 sigmas. These ionospheric disturbances were probably associated with prompt penetration electric fields (PPEFs) and equatorward neutral winds. On the other hand, during four geomagnetic storms (August 12, 2000, March 31, 2001, April 11, 2001 and May 15, 2005), there were negative ionospheric storms that pushed the TEC to significantly lower values. This has been interpreted as the presence of regions in which the neutral composition is changed. Also, in some cases during the disturbed days, the Hurst values were smaller than during the undisturbed days, i.e. during these geomagnetic storms, the roughness of the time series of TEC increased. The wavelet analysis showed a strong influence of the diurnal variation on TEC values (periodicities of 12 h), and periodicities characteristics of ionospheric disturbances of 1-8 h. It is found that large geomagnetic storms produce significant ionospheric disturbances at mid latitudes, as shown by the wavelet analysis and, in some cases, changes in the roughness of the time series of

  6. A neural network-based local model for prediction of geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Gleisner, Hans; Lundstedt, Henrik

    2001-05-01

    This study shows how locally observed geomagnetic disturbances can be predicted from solar wind data with artificial neural network (ANN) techniques. After subtraction of a secularly varying base level, the horizontal components XSq and YSq of the quiet time daily variations are modeled with radial basis function networks taking into account seasonal and solar activity modulations. The remaining horizontal disturbance components ΔX and ΔY are modeled with gated time delay networks taking local time and solar wind data as input. The observed geomagnetic field is not used as input to the networks, which thus constitute explicit nonlinear mappings from the solar wind to the locally observed geomagnetic disturbances. The ANNs are applied to data from Sodankylä Geomagnetic Observatory located near the peak of the auroral zone. It is shown that 73% of the ΔX variance, but only 34% of the ΔY variance, is predicted from a sequence of solar wind data. The corresponding results for prediction of all transient variations XSq+ΔX and YSq+ΔY are 74% and 51%, respectively. The local time modulations of the prediction accuracies are shown, and the qualitative agreement between observed and predicted values are discussed. If driven by real-time data measured upstream in the solar wind, the ANNs here developed can be used for short-term forecasting of the locally observed geomagnetic activity.

  7. High-latitude geomagnetic disturbances during ascending solar cycle 24

    NASA Astrophysics Data System (ADS)

    Peitso, Pyry; Tanskanen, Eija; Stolle, Claudia; Berthou Lauritsen, Nynne; Matzka, Jürgen

    2015-04-01

    High-latitude regions are very convenient for study of several space weather phenomena such as substorms. Large geographic coverage as well as long time series of data are essential due to the global nature of space weather and the long duration of solar cycles. We will examine geomagnetic activity in Greenland from magnetic field measurements taken by DTU (Technical University of Denmark) magnetometers during the years 2010 to 2014. The study uses data from 13 magnetometer stations located on the east coast of Greenland and one located on the west coast. The original measurements are in one second resolution, thus the amount of data is quite large. Magnetic field H component (positive direction towards the magnetic north) was used throughout the study. Data processing will be described from calibration of original measurements to plotting of long time series. Calibration consists of determining the quiet hour of a given day and reducing the average of that hour from all the time steps of the day. This normalizes the measurements and allows for better comparison between different time steps. In addition to the full time line of measurements, daily, monthly and yearly averages will be provided for all stations. Differential calculations on the change of the H component will also be made available for the duration of the full data set. Envelope curve plots will be presented for duration of the time line. Geomagnetic conditions during winter and summer will be compared to examine seasonal variation. Finally the measured activity will be compared to NOAA (National Oceanic and Atmospheric Administration) issued geomagnetic space weather alerts from 2010 to 2014. Calculations and plotting of measurement data were done with MATLAB. M_map toolbox was used for plotting of maps featured in the study (http://www2.ocgy.ubc.ca/~rich/map.html). The study was conducted as a part of the ReSoLVE (Research on Solar Long-term Variability and Effects) Center of Excellence.

  8. 77 FR 24952 - Staff Technical Conference on Geomagnetic Disturbances to the Bulk-Power System; Technical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-26

    ... Energy Regulatory Commission Staff Technical Conference on Geomagnetic Disturbances to the Bulk-Power.... to 4:00 p.m. to discuss issues related to the reliability of the Bulk-Power System as affected by... currents to transformers and other equipment on the Bulk-Power System, as well as, options for...

  9. 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.

  10. Day-to-day variability in the development of plasma bubbles associated with geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Abalde, J. R.; Sahai, Y.; Fagundes, P. R.; Becker-Guedes, F.; Bittencourt, J. A.; Pillat, V. G.; Lima, W. L. C.; Candido, C. M. N.; de Freitas, T. F.

    2009-04-01

    The development of equatorial ionospheric irregularities into large-scale ionospheric plasma bubbles continues to be an active area for scientific investigations. In this paper, we present simultaneous OI 630.0-nm emission all-sky imaging observations carried out at the Astrophysics National Laboratory (LNA), Brazopolis (22.5°S, 45.6°W, altitude 1860 m) and ionospheric sounding observations carried out at Palmas (10.2°S, 48.2°W located close to the magnetic equator) and Sao Jose dos Campos (23.2°S, 45.9°W located under the southern crest of equatorial ionospheric anomaly, close to Brazopolis), Brazil, to study the day-to-day variability in the development of ionospheric plasma bubbles during both geomagnetically disturbed and quiet periods in September-October 2002. Also, we present simultaneous complementary phase fluctuation (ROT) data obtained from the global position system (GPS) meridional chain operated by the Brazilian Institute of Geography and Statistic (IBGE). On the three nights studied in the present investigation (one geomagnetically quiet and two geomagnetically disturbed), it has been observed that the geomagnetic disturbances, during this spring equinox period, have a strong effect on the generation and development of ionospheric plasma bubbles.

  11. Multi-stations Observations of the Atmospheric Electrical Parameters during Geomagnetic Disturbances

    NASA Astrophysics Data System (ADS)

    Nepolian, Jeni Victor; Frank-Kamenetsky, Alexander; Panneerselvam, C.; Manu, S.; Anil Kumar

    2016-07-01

    The effects of geomagnetic disturbances on the variation of atmospheric electric field over Maitri (70o 45' S, 11o44' E), Dome C (75° 06' S, 123° 20' E) and Vostok (78° 27' S, 106° 52' E) Antarctic research stations are presented in this work. For the first time the paper reports simultaneous observations of the atmospheric electric field from 2010 to 2012 of over three high latitude stations in Southern Hemisphere, and its associated changes due to geomagnetic disturbances. Near surface electric fields obtained from the three stations are analyzed. It is noted that the amplitude of change in surface electric field is highly dependent on the magnetic latitude during geomagnetic disturbances. The maximum deviation is observed near to the geomagnetic pole (Dome C) during strong magnetic perturbation, but not on the foci of the convection cells. It is due to the effective downward mapping of large scale horizontal ionospheric electric field. Interestingly, the phase of downward current is highly associated with magnetospheric electric field, moreover, its imprint is clearly observed in the magnetic and electric field variations on the earth's surface. The present observations provide an evidence for the changes on surface electric field due to spatial extension of convection cell. The inferences will be discussed in the conference.

  12. Magnetospheric transmissivity for cosmic rays during selected recent events with interplanetary/geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Parnahaj, I.; Bobík, P.; Kudela, K.

    2015-08-01

    The variability of cosmic rays (CRs) observed at selected European neutron monitors (NMs) around moderate geomagnetic disturbances, namely during the intervals (a) DOY 49-51 in 2014, (b) DOY 58-59 in 2014, (c) DOY 238-240 in 2014 and (d) DOY 6-8 in 2015 is discussed. Assuming the primary spectra of the CREME96 model, the yield function and geomagnetic transmissivity changes provided by the Tsyganenko96 model, the expected increases at the mid-latitude station Lomnický štít are compared with the observed ones. The examples stress the importance of including anisotropy of the CR flux in interplanetary space, the use of other geomagnetic field models and other yield functions to the computations in future analysis.

  13. Ionospheric and geomagnetic disturbances caused by the 2008 Wenchuan earthquake: A revisit

    NASA Astrophysics Data System (ADS)

    Zhao, Biqiang; Hao, Yongqiang

    2015-07-01

    Previous works have shown that coseismic ionospheric disturbances (CIDs) after the tsunamigenic 2011 Tohoku earthquake (Tohoku EQ, Mw9.1) covered a vast area and were observed thousands of kilometers away from the epicenter. For the purpose of making a comprehensive comparison between powerful oceanic and inland EQs, we conduct a retrospective investigation of CIDs and geomagnetic responses to the 2008 Wenchuan EQ (Mw7.9) using a combination of techniques, total electron content, HF Doppler, and ground magnetometer. It is the very first study to present CIDs recorded by different techniques at co-located sites and profiled with regard to changes of both ionospheric plasma and current (geomagnetic field) simultaneously. The integrated observation also shows that (1) in the Wenchuan case, most of the ionospheric and geomagnetic disturbances were observed within 1000 km distance which is far less than the Tohoku case; (2) two groups of CIDs were found with maximum amplitudes in the direction of azimuth 150° and 135°, respectively; and (3) the geomagnetic changes were only registered by three magnetometers located to the east and southeast of the epicenter. All the facts indicate that the main directional lobe of Wenchuan EQ energy propagation is to southeast and perpendicular to the direction of the fault rupture, but this kind of directivity is not that distinct in the Tohoku case. We suggest that the different fault slip (inland or submarine) affecting the way of couplings of lithosphere with atmosphere may contribute to the discrepancies between the two events.

  14. Geomagnetic disturbances on ground associated with particle precipitation during SC

    NASA Astrophysics Data System (ADS)

    Safargaleev, V.; Kozlovsky, A.; Honary, F.; Voronin, A.; Turunen, T.

    2010-01-01

    We have examined several cases of magnetosphere compression by solar wind pressure pulses using a set of instruments located in the noon sector of auroral zone. We have found that the increase in riometric absorption (sudden commencement absorption, SCA) occurred simultaneously with the beginning of negative or positive magnetic variations and broadband enhancement of magnetic activity in the frequency range above 0.1 Hz. Since magnetic variations were observed before the step-like increase of magnetic field at equatorial station (main impulse, MI), the negative declinations resembled the so-called preliminary impulse, PI. In this paper a mechanism for the generation of PI is introduced whereby PI's generation is linked to SCA - associated precipitation and the local enhancement of ionospheric conductivity leading to the reconstruction of the ionospheric current system prior to MI. Calculation showed that PI polarity depends on orientation of the background electric field and location of the observation point relative to ionospheric irregularity. For one case of direct measurements of electric field in the place where the ionospheric irregularity was present, the sign of calculated disturbance corresponded to the observed one. High-resolution measurements on IRIS facility and meridional chain of the induction magnetometers are utilized for the accurate timing of the impact of solar wind irregularity on the magnetopause.

  15. 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

  16. Application of the SP algorithm to the INTERMAGNET magnetograms of the disturbed geomagnetic field

    NASA Astrophysics Data System (ADS)

    Sidorov, R. V.; Soloviev, A. A.; Bogoutdinov, Sh. R.

    2012-05-01

    The algorithmic system developed in the Laboratory of Geoinformatics at the Geophysical Center, Russian Academy of Sciences, which is intended for recognizing spikes on the magnetograms from the global network INTERMAGNET provides the possibility to carry out retrospective analysis of the magnetograms from the World Data Centers. Application of this system to the analysis of the magnetograms allows automating the job of the experts-interpreters on identifying the artificial spikes in the INTERMAGNET data. The present paper is focused on the SP algorithm (abbreviated from SPIKE) which recognizes artificial spikes on the records of the geomagnetic field. Initially, this algorithm was trained on the magnetograms of 2007 and 2008, which recorded the quiet geomagnetic field. The results of training and testing showed that the algorithm is quite efficient. Applying this method to the problem of recognizing spikes on the data for periods of enhanced geomagnetic activity is a separate task. In this short communication, we present the results of applying the SP algorithm trained on the data of 2007 to the INTERMAGNET magnetograms for 2003 and 2005 sampled every minute. This analysis shows that the SP algorithm does not exhibit a worse performance if applied to the records of a disturbed geomagnetic field.

  17. 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.

  18. 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.

  19. Cross-spectral coherence between geomagnetic disturbance and human cardiovascular variables at non-societal frequencies.

    PubMed

    Watanabe, Y; Hillman, D C; Otsuka, K; Bingham, C; Breus, T K; Cornélissen, G; Halberg, F

    1994-01-01

    A 35-year-old cardiologist monitored himself with an automatic ABPM-630 (Colin Electronics) monitor, mostly at 15-minute intervals around-the-clock for three years with a few interruptions. In this subject with a family history of high blood pressure and stroke, a cross-spectral analysis revealed a statistically significant coherence at 27.7 days between systolic and diastolic blood pressure and heart rate vs. the geomagnetic disturbance index, Kp. A lesser peak in coherence was found for systolic blood pressure with Kp at a trial period of 4.16 days (P = 0.046). These results suggest that changes in geomagnetism may influence the human circulation, at least in the presence of familial cardiovascular disease risk, and they may do so at frequencies that have no precise human-made cyclic worldwide match. PMID:7729242

  20. Variation of surface electric field during geomagnetic disturbed period at Maitri, Antarctica

    NASA Astrophysics Data System (ADS)

    Victor, N. Jeni; Panneerselvam, C.; Anil Kumar, C. P.

    2015-12-01

    The paper discusses on the variations of the atmospheric vertical electric field measured at sub-auroral station Maitri (70∘75'S, 11∘75'E), and polar station Vostok (78.5∘S, 107∘E) during the geomagnetic disturbances on 25-26 January 2006. Diurnal variation of surface electric field measured at Maitri shows a similar variation with worldwide thunderstorm activity, whereas the departure of the field is observed during disturbed periods. This part of the field corresponds to the magnetospheric/ionospheric (an additional generator in the polar regions) voltage generators. Solar wind parameters and planetary indices represent the temporal variation of the disturbances, and digital fluxgate magnetometer variation continuously monitored to trace the auroral movement at Maitri. We have observed that the electrojet movement leaves its signature on vertical and horizontal components of the DFM in addition; the study infers the position of auroral current wedge with respect to Maitri. To exhibit the auroral oval, OVATION model is obtained with the aid of DMSP satellite and UV measurements. It is noted that the Maitri is almost within the auroral oval during the periods of disturbances. To examine the simultaneous changes in the vertical electric field associated with this magnetic disturbance, the dawn-dusk potential is studied for every UT hours; the potential was obtained from Weimer model and SuperDARN radar. The comparison reveals the plausible situation for the superposition of dawn-dusk potential on surface electric field over Maitri. This observation also shows that the superposition may not be consistent with the phase of the electrojet. Comparison of surface electric field at Maitri and Vostok shows that the parallel variation exhibits with each other, but during the period of geomagnetic disturbances, the influence is not much discerned at Vostok.

  1. Co-located ionospheric and geomagnetic disturbances caused by great earthquakes

    NASA Astrophysics Data System (ADS)

    Hao, Yongqiang; Zhang, Donghe; Xiao, Zuo

    2016-07-01

    Despite primary energy disturbances from the Sun, oscillations of the Earth surface due to a large earthquake will couple with the atmosphere and therefore the ionosphere, to generate so-called coseismic ionospheric disturbances (CIDs). In the cases of 2008 Wenchuan and 2011 Tohoku earthquakes, infrasonic waves accompanying the propagation of seismic Rayleigh waves were observed in the ionosphere by a combination of techniques, total electron content, HF Doppler, and ground magnetometer. This is the very first report to present CIDs recorded by different techniques at co-located sites and profiled with regard to changes of both ionospheric plasma and current (geomagnetic field) simultaneously. Comparison between the oceanic (2011 Tohoku) and inland (2008 Wenchuan) earthquakes revealed that the main directional lobe of latter case is more distinct which is perpendicular to the direction of the fault rupture. We argue that the different fault slip (inland or submarine) may affect the way of couplings of lithosphere with atmosphere. Zhao, B., and Y. Hao (2015), Ionospheric and geomagnetic disturbances caused by the 2008 Wenchuan earthquake: A revisit, J. Geophys. Res., doi:10.1002/2015JA021035. Hao, Y. Q., et al. (2013), Teleseismic magnetic effects (TMDs) of 2011 Tohoku earthquake, J. Geophys. Res., doi:10.1002/jgra.50326. Hao, Y. Q., et al. (2012), Multi-instrument observation on co-seismic ionospheric effects after great Tohoku earthquake, J. Geophys. Res., doi:10.1029/2011JA017036.

  2. Mid-Latitude Ionospheric Disturbances Due to Geomagnetic Storms at ISS Altitudes

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Willis, Emily M.; Parker, Linda Neergaard

    2014-01-01

    Spacecraft charging of the International Space Station (ISS) is dominated by the interaction of the high voltage US solar arrays with the F2-region ionospheric plasma environment. We are working to fully understand the charging behavior of the ISS solar arrays and determine how well future charging behavior can be predicted from in-situ measurements of plasma density and temperature. One aspect of this work is a need to characterize the magnitude of electron density and temperature variations that may be encountered at ISS orbital altitudes (approximately 400 km), the latitudes over which they occur, and the time periods for which the disturbances persist. We will present preliminary results from a study of ionospheric disturbances in the "mid-latitude" region defined as the approximately 30 - 60 degree extra-equatorial magnetic latitudes sampled by ISS. The study is focused on geomagnetic storm periods because they are well known drivers for disturbances in the high-latitude and mid-latitude ionospheric plasma. Changes in the F2 peak electron density obtained from ground based ionosonde records are compared to in-situ electron density and temperature measurements from the CHAMP and ISS spacecraft at altitudes near, or above, the F2 peak. Results from a number of geomagnetic storms will be presented and their potential impact on ISS charging will be discussed.

  3. Severe ionosphere disturbances caused by the sudden response of evening subequatorial ionospheres to geomagnetic storms

    SciTech Connect

    Tanaka, T.

    1981-12-01

    By monitoring C band beacon signals from geostationary satellites in Japan, we have observed anomalously strong ionospheric scintillations several times during three years from 1978 to 1980. These severe scinitillations occur associated with geomagnetic storms and accompany sudden and intense ionospheric perturbations in the low-latiude region. Through the analysis of these phenomena we have identified a new type of ionospheric disturbances characterized by intensifications of equatorial anomalies and successive severe ionospheric scintillations that extend to the C band range. The events occur only during a limited local time interval after the sunset, when storm time decreases of midlatitude geomagnetic fields in the same meridan take place during the same time interval. From the viewpoint of ionospheric storms, these disturbances precede the occurrence of midlatitude negative phases and storm time depressions of equatorial anomalies to indicate that the cause of the events is different from distrubed thermospheric circulations. The timing and magnitude of substorms at high-latitudes not always correlate with the events. We have concluded that the phenomena are closely related with penetrations toward low-latitudes of electric fields owing to the partial closure of asymmetrical ring currents.

  4. 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

  5. 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.

  6. Investigation of a strong positive ionospheric storm during geomagnetic disturbances occurred in the Brazilian sector

    NASA Astrophysics Data System (ADS)

    de Abreu, A. J.; Sahai, Y.; Fagundes, P. R.; de Jesus, R.; Bittencourt, J. A.; Pillat, V. G.

    2012-12-01

    In this paper, we have investigated the responses of the ionospheric F region at equatorial and low latitude regions in the Brazilian sector during the super geomagnetic storm on 15-16 May 2005. The geomagnetic storm reached a minimum Dst of -263 nT at 0900 UT on 15 May. In this paper, we present vertical total electron content (vTEC) and phase fluctuations (in TECU/min) from Global Positioning System (GPS) observations obtained at Belém (BELE), Brasília (BRAZ), Presidente Prudente (UEPP), and Porto Alegre (POAL), Brazil, during the period 14-17 May 2005. Also, we present ionospheric parameters h'F, hpF2, and foF2, using the Canadian Advanced Digital Ionosonde (CADI) obtained at Palmas (PAL) and São José dos Campos (SJC), Brazil, for the same period. The super geomagnetic storm has fast decrease in the Dst index soon after SSC at 0239 UT on 15 May. It is a good possibility of prompt penetration of electric field of magnetospheric origin resulting in uplifting of the F region. The vTEC observations show a trough at BELE and a crest above UEPP, soon after SSC, indicating strengthening of nighttime equatorial anomaly. During the daytime on 15 and 16 May, in the recovery phase, the variations in foF2 at SJC and the vTEC observations, particularly at BRAZ, UEPP, and POAL, show large positive ionospheric storm. There is ESF on the all nights at PAL, in the post-midnight (UT) sector, and phase fluctuations only on the night of 14-15 May at BRAZ, after the SSC. No phase fluctuations are observed at the equatorial station BELE and low latitude stations (BRAZ, UEPP, and POAL) at all other times. This indicates that the plasma bubbles are generated and confined on this magnetically disturbed night only up to the low magnetic latitude and drifted possibly to west.

  7. Multi-instrumental Analysis of the Ionospheric Density Response to Geomagnetic Disturbances

    NASA Astrophysics Data System (ADS)

    Zakharenkova, I.; Astafyeva, E.

    2014-12-01

    Measurements provided by Low Earth Orbit (LEO) satellite missions have already proved to be very efficient in investigations of global redistribution of ionospheric plasma and thermosphere mass density during such phenomena as geomagnetic storms. LEO satellites have various instruments for research of the ionosphere response to the space weather events like GPS receiver for precise orbit determination (POD), total electron content estimation and radio occultation, altimeter, planar Langmuir probe, topside sounder, special detectors for particle fluxes, magnetometer etc. In this paper, we present results of joint analysis of LEO satellite data, in particular CHAMP, DMSP, JASON, as well as data provided by ground-based networks of GPS receivers and ionosonde stations for global ionospheric response to the geomagnetic disturbances. We use in-situ plasma density data from CHAMP and DMSP satellites, along with data of GPS receiver onboard CHAMP-satellite and ground-based GPS-receivers to study occurrence and global distribution of ionospheric irregularities during the main phase of the storm. Using CHAMP GPS measurements, we created maps of GPS phase fluctuation activity and found two specific zones of the most intense irregularities - first is the region of the auroral oval at high latitudes of both hemispheres, the second one is the low-latitudes/equatorial region between Africa and South America. The interhemispheric asymmetry of the ionospheric irregularities intensity and occurrence in polar region is discussed. Analysis of the topside TEC, derived from CHAMP onboard GPS POD antenna, indicate the significant redistribution of the topside ionospheric plasma density in the equatorial, middle and high-latitude ionosphere during main and recovery phases of geomagnetic storm. Multi-instrumental data allow to analyze in detail the complex modification and dynamics of the upper atmosphere in different altitudinal, spatial and temporal scales.

  8. Traveling ionospheric disturbances in the Weddell Sea Anomaly associated with geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Milan, S. E.; Grocott, A.; Larquier, S.; Lester, M.; Yeoman, T. K.; Freeman, M. P.; Chisham, G.

    2013-10-01

    present observations from the Falkland Islands Super Dual Auroral Radar Network radar of the propagation of HF radio waves via the Weddell Sea Ionospheric Anomaly (WSA), a region of enhanced austral summer nighttime ionospheric electron densities covering the southern Pacific and South Americas region. This anomaly is thought to be produced by uplift of the ionosphere by prevailing equatorward thermospheric winds. Of particular interest are perturbations of the WSA-supported propagation, which suggest that during periods of geomagnetic disturbance, the ionospheric layer can be lowered by several tens of kilometers and subsequently recover over a period of 1 to 2 h. Perturbations can appear singly or as a train of two to three events. We discuss possible causes of the perturbations and conclude that they are associated with equatorward propagating large-scale atmospheric waves produced by magnetospheric energy deposition in the auroral or subauroral ionosphere. Changes in high/middle latitude electrodynamics during geomagnetic storms may also account for the perturbations, but further modeling is required to fully understand their cause.

  9. Establishing the Geomagnetic Disturbance Benchmark Event for Evaluation of the Space Weather Hazard on Power Grids

    NASA Astrophysics Data System (ADS)

    Pulkkinen, A. A.; Bernabeu, E.; Eichner, J.

    2014-12-01

    The awareness about potential major impact geomagnetically induced currents (GIC) can have on the North American high-voltage power transmission system has prompted Federal Energy Regulatory Commission (FERC) to launch a geomagnetic disturbances (GMD) standards drafting process. The goals of the GMD standards are to quantify and mitigate the GMD hazard on the North American grid. North American Electric Reliability Corporation's (NERC) is coordinating the standards drafting process that is now entering Phase II involving quantification of the impact GIC can have on individual parts of the North American grid. As a part of the Phase II GMD standards drafting process, substantial effort has been made for generating benchmark GMD scenarios. These scenarios that quantify extreme geoelectric field magnitudes and temporal waveforms of the field fluctuations are the foundation for subsequent engineering and impacts analyses. The engineering analyses will include the transmission system voltage stability and transformer heating assessments. The work on the GMD scenarios has been a major collaboration between a number of international entities involved in GMD research and transmission system operations. We will discuss in this paper the key elements of the benchmark GMD generation process and show the latest results from our work on the topic.

  10. Investigation of the responses of the general circulation at 700 mb to solar-geomagnetic disturbance

    NASA Technical Reports Server (NTRS)

    Stolov, H. L.; Shapiro, R.

    1973-01-01

    The Northern Hemisphere 700 mb contour heights from 20 N to 70 N for the period 1947-1970 are studied in conjunction with 272 key days, where the daily increase of the Ci index equals or exceeds 1.0. The superposed epoch method is applied from 33 days before to 66 days after the key day for a variety of zonal and meridional indices. It is shown that the 700 mb height difference between 20 N and 55 N increases significantly in winter 4 days following geomagnetic disturbance (in summer a less prominent but statistically significant increase is found 2 days earlier). The effect is most clear in winter in the quadrant 90-175 W and corresponds to a 7% increase in the mean geostrophic westerly flow. The statistical significance of the results is established by applying Student's t-test to the difference of each daily mean from the continuum.

  11. DE 2 observations of disturbances in the upper atmosphere during a geomagnetic storm

    SciTech Connect

    Miller, N.J.; Brace, L.H.; Spencer, N.W. ); Carignan, G.R. )

    1990-12-01

    Data taken in the dusk sector of the mid-latitude thermosphere at 275-450 km by instruments on board Dynamics Explorer 2 in polar orbit are used to examine the response of the ionosphere- thermosphere system during a geomagnetic storm. The results represent the first comparison of nearly simultaneous measurements of storm disturbances in dc electric fields, zonal ion convection, zonal winds, gas composition and temperature, and electron density and temperature, at different seasons in a common local time sector. The storm commenced on November 24, 1982, during the interaction of a solar wind disturbance with the geomagnetic field while the north-south component of the interplanetary magnetic field, B{sub z}, was northward. The storm main phase began while B{sub z} was turning southward. Storm-induced variations in meridional de electric fields, neutral composition, and N{sub e} were stronger and spread farther equatorward in the winter hemisphere. Westward ion convection was intense enough to produce westward winds of 600 m s{sup {minus} 1} via ion drag in the winter hemisphere. Frictional heating was sufficient to elevate ion temperatures above electron temperatures in both seasons and to produce large chemical losses of O{sup +} by increasing the rate of O{sup +} loss via ion-atom interchange. Part of the chemical loss of O{sup +} was compensated by upward flow of O{sup +} as the ion scale height adjusted to the increasing ion temperatures. In this storm, frictional heating was an important subauroral heat source equatorward to at least 53{degree} invariant latitude.

  12. Spectral characteristics of plasma sheet ion and electron populations during disturbed geomagnetic conditions

    SciTech Connect

    Christon, S.P., Williams, D.J.; Mitchell, D.G. ); Huang, C.Y.; Frank, L.A. )

    1991-01-01

    The authors have determined the spectral characteristics of central plasma sheet ions and electrons observed during 71 hours when geomagnetic activity was at moderate to high levels (AE {ge} 100nT). Particle data from the low-energy proton and electron differential energy analyzer and the medium energy particle instrument on ISEE 1 are combined to obtain differential energy spectra (measured in units of particles/cm{sup 2} s sr keV) in the kinetic energy range {approximately}30 eV/e to {approximately}1 MeV at geocentric radial distances >12R{sub e}. Nearly isotropic central plasma sheet total ion and electron populations were chosen for analysis and were measured to be continuous particle distributions from the lowest to highest energies. During these high AE periods the >24 keV particle fluxes and the temperature of the entire particle distribution kT are significantly higher than during low AE periods (AE < 100 nT). The temperatures kT{sub i} and kT{sub e} are highly correlated during both quiet and disturbed periods. The active period spectral shape appears softer for ions and somewhat harder for electrons than during quiet periods. They find that the observed active period spectrum typically is complex and cannot be represented in general by a single functional form, as during quiet periods when it can be represented by the kappa distribution function. In a limited energy range near the knee of the ion spectra, the spectral shape can often be fit with a Maxwellian form, thus rolling over faster than the typical quiet time spectrum. Electron spectra also display this spectral characteristic, although at a lower occurence frequency than for ions. The electron spectra are predominantly kappalike at energies near and above the knee. The authors conclude that both ions and electrons participate in at least two separate accerlation mechanisms as geomagnetic activity evolves from low AE to high AE values.

  13. Mid-Latitude Ionospheric Disturbances Due to Geomagnetic Storms at ISS Altitudes

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Willis, Emily M.; Neergaard Parker, Linda

    2014-01-01

    Spacecraft charging of the International Space Station (ISS) is dominated by interaction of the US high voltage solar arrays with the F2-region ionosphere plasma environment. ISS solar array charging is enhanced in a high electron density environment due to the increased thermal electron currents to the edges of the solar cells. High electron temperature environments suppress charging due to formation of barrier potentials on the charged solar cell cover glass that restrict the charging currents to the cell edge [Mandell et al., 2003]. Environments responsible for strong solar array charging are therefore characterized by high electron densities and low electron temperatures. In support of the ISS space environmental effects engineering community, we are working to understand a number of features of solar array charging and to determine how well future charging behavior can be predicted from in-situ plasma density and temperature measurements. One aspect of this work is a need to characterize the magnitude of electron density and temperature variations that occur at ISS orbital altitudes (approximately 400 km) over time scales of days, the latitudes over which significant variations occur, and the time periods over which the disturbances persist once they start. This presentation provides examples of mid-latitude electron density and temperature disturbances at altitudes relevant to ISS using data sets and tools developed for our ISS plasma environment study. "Mid-latitude" is defined as the extra-tropical region between approx. 30 degrees to approx. 60 degrees magnetic latitude sampled by ISS over its 51.6 degree inclination orbit. We focus on geomagnetic storm periods because storms are well known drivers for disturbances in the ionospheric plasma environment.

  14. 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.

  15. 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.

  16. Modelling the disturbance caused by a dc-electrified railway to geomagnetic measurements

    NASA Astrophysics Data System (ADS)

    Pirjola, R.; Newitt, L.; Boteler, D.; Trichtchenko, L.; Fernberg, P.; McKee, L.; Danskin, D.; Jansen van Beek, G.

    2007-08-01

    Magnetic fields created by a dc-electrified railway are a nuisance to the operation of a geomagnetic observatory and also disturb other electromagnetic studies. Theoretical formulas that enable quantitative estimates of the magnetic effect of a dc railway including leakage currents in the ground are presented in this paper. They are illustrated by numerical examples. The validity of the theoretical model was verified by measurements carried out in the vicinity of a nearly north-south railway in Calgary, Canada. The earth structure in that area is approximately layered, which is an assumption included in the theoretical model. The agreement between the measured magnetic fields due to trains and the theoretical values is good. Numerical computations indicate that magnetic fields larger than the maximum allowable noise level (assumed to be about 10 pT) at today's magnetic observatories may extend to distances of tens of kilometres from a railway. We have prepared computer programs based on the theoretical formulas in the MatLab, Octave, FORTRAN and IDL languages, in which the locations (i.e. the latitudes and the longitudes) of the point of observation, of the feeding substations and of the trains, together with the feeding and leakage currents and the heights of the feeding lines, can be given as inputs.

  17. 27-day variation of the GCR intensity based on corrected and uncorrected for geomagnetic disturbances data of neutron monitors

    NASA Astrophysics Data System (ADS)

    Alania, M. V.; Modzelewska, R.; Wawrzynczak, A.; Sdobnov, V. E.; Kravtsova, M. V.

    2015-08-01

    We study 27-day variations of the galactic cosmic ray (GCR) intensity for 2005-2008 period of the solar cycle #23. We use neutron monitors (NMs) data corrected and uncorrected for geomagnetic disturbances. Besides the limited time intervals when the 27-day variations are clearly established, always exist some feeble 27-day variations in the GCR intensity related to the constantly present weak heliolongitudinal asymmetry in the heliosphere. We calculate the amplitudes of the 27-day variation of the GCR intensity based on the NMs data corrected and uncorrected for geomagnetic disturbances. We show that these amplitudes do not differ for NMs with cut-off rigidities smaller than 4-5 GV comparing with NMs of higher cut-off rigidities. Rigidity spectrum of the 27-day variation of the GCR intensity found in the uncorrected data is soft while it is hard in the case of the corrected data. For both cases exists definite tendency of softening the temporal changes of the 27-day variation's rigidity spectrum in period of 2005 to 2008 approaching the minimum of solar activity. We believe that a study of the 27-day variation of the GCR intensity based on the data uncorrected for geomagnetic disturbances should be carried out by NMs with cut-off rigidities smaller than 4-5 GV.

  18. The width of the frequency spectrum of Pc1 geomagnetic pulsations in quiet and disturbed conditions

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    The relation of the frequency spectrum width of Pc1 geomagnetic pulsations with magnetospheric parameters was theoretically studied. An analytical expression was obtained and numerical calculations were conducted. The formula for the increment (γ) was shown to include an important magnetospheric parameter, the ratio ( V A/ U ‖) of the Alfven velocity to the average velocity of energetic protons along the field line, which significantly affects the frequency spectrum width. The calculations show that the normalized width of the Pc1 frequency spectrum ( x 0 = ωout/Ω i = V A/ U ‖) decreases with decreasing ( V A/ U ‖). With increasing anisotropy of energetic protons A = T ⊥/ T ‖ - 1, the normalized width of Pc1 frequency spectrum is also decreased for a fixed value of the parameter ( V A/ U ‖). These conclusions have been confirmed by analysis of spectrograms conducted in 2005-2010 of ground-based observations of Pc1 on the Scandinavian network of induction magnetometers. Analysis of these data showed that Pc1 pulsations were observed in a narrow frequency band of around 0.2-0.4 Hz, with a central frequency of oscillations in the series f ˜ 0.5-0.7 Hz, in more than 90% of cases in magnetically quiet conditions ( Kp < 2). This corresponds to their generation beyond the plasmasphere. In more disturbed conditions ( Kp ˜ 2-3), the central frequency of Pc1 oscillations was almost twice greater (˜ 1.0-1.2 Hz) and the spectral width was ˜ 0.5-0.7 Hz, which makes it possible to suggest that they can be generated within the plasmasphere.

  19. Observations from Millstone Hill during the geomagnetic disturbances of March and April 1990

    SciTech Connect

    Buonsanto, M.J.; Foster, J.C.; Sipler, D.P. )

    1992-02-01

    The incoherent scatter radars at Millstone Hill operated continuously during the periods March 16-23 and April 6-12, 1990, providing observations of large-scale ionospheric structure and dynamics over a large portion of eastern North America. Major geomagnetic storms occurred during each of these periods, with deep nighttime ionospheric troughs and large magnetospheric convection electric fields observed equatorward of Millstone. The Millstone observations provide a comprehensive data set detailing storm-induced ionospheric effects over a 35{degree} span of latitude during both of these intervals. At the latitude of Millstone the ionospheric peak height hmF2 rose above 600 km the into trough on March 22 and 23 and reached {approx}500 km at night on April 11 and 12. Increased recombination, apparently due to the strong electric fields, te temperature dependent recombination rate coefficient, and neutral composition changes, greatly depleted the F2 region over a wide latitude range during the day on April 10, 1990. This resulted in an ionosphere dominated by molecular ions, with ionospheric peak heights below 200 km on this day. A number of frictional heating events during the disturbed periods are seen from comparison of ion temperature and velocity measurements. The most intense event took place near 1200 UT on April 10, 1990, when Kp reached 8. At 0100 UT on March 21, line of sight ion velocities in excess of 500 ms{sup {minus}1} were observed at the extreme southern limit of the Millstone steerable radar's field of view (40{degree} apex magnetic latitude at an altitude of 700 km). These could be due to penetration of magnetospheric electric fields or electric fields associated with ring current shielding in the storm-time outer plasmasphere. About an hour later, ion outflow was observed just equatorward of Millstone.

  20. Observed geomagnetic induction effect on Dst-related magnetic observations under different disturbance intensities of the magnetospheric ring current

    NASA Astrophysics Data System (ADS)

    Xu, Dan; Chen, Huaran; Gao, Mengtan

    2015-01-01

    Based on the spherical harmonic expansion of geomagnetic disturbance observed on the mid-latitude surface of the Earth, external and internal field separation is conducted in which the external component is magnetic disturbance caused by the magnetospheric ring current and the internal component is that raised by the correspondingly induced currents within the Earth. The objectives are to evaluate the influences of the induced internal field on the surface magnetic observations and to reveal the response performance of internal geomagnetic induction under different strengths of magnetospheric ring current fluctuations for better understanding of the disturbance storm time ( Dst) index variations. The results show that the ratio of the internal component to surface observation does not remain constant in storm time. During the main phase of the storm, the ratio variation follows the pattern of logarithmic growth with storm evolution up to the top value at the Dst-minimum; then, the ratio slowly decreases in the long recovery phase. Multiple small logarithmic growths are superimposed on the traces of internal ratios, corresponding to temporary ring current intensification during the storm main phase and amplifying the effect of this intensification on surface magnetic observations. With the intensification of magnetospheric storms from the level of (-200 nT, - 100 nT) to (-300 nT, - 200 nT) and (-500 nT, - 300 nT) classified with the Dst-minimum, the top value of the ratio averaged for each storm group in the superposed epoch analysis method increases from the value of 0.295 ± 0.014 to 0.300 ± 0.016 and 0.308 ± 0.015, respectively. It is demonstrated that the geomagnetic induction exceeds the linear relation with the intensification of the external field, which is physically reasonable and coincident with the Faraday's law of induction. Due to the effects of high induction of the oceans and lateral heterogeneity of electric conductivity distribution in the upper

  1. Comment on the existence of a long range correlation in the geomagnetic disturbance storm time (Dst) index

    NASA Astrophysics Data System (ADS)

    Lacasa, Lucas

    2012-01-01

    Very recently (Banerjee et al. in Astrophys. Space, doi:10.1007/s10509-011-0836-1, 2011) the statistics of geomagnetic Disturbance storm (Dst) index have been addressed, and the conclusion from this analysis suggests that the underlying dynamical process can be modeled as a fractional Brownian motion with persistent long-range correlations. In this comment we expose several misconceptions and flaws in the statistical analysis of that work. On the basis of these arguments, the former conclusion should be revisited.

  2. Weather and infradian rhythms in self-reports of health, sleep and mood measures.

    PubMed

    Whitton, J L; Kramer, P; Eastwood, R

    1982-01-01

    Some individuals exhibit significant and sustained periodicities in their self-reports of physical well-being, mood, hours of sleep, anxiety and cognition. These infradian rhythms may be related to weather variables such as solar flux, barometric pressure, temperature and humidity. The time of year, or season, during which self-reporting is performed may predicate the infradian rhythms and their relationship to weather. PMID:7077554

  3. Geomagnetic transmission disturbances and heavy-ion fluences observed in low Earth orbit during the solar energetic particle events of October 1989

    NASA Technical Reports Server (NTRS)

    Boberg, P. R.; Tylka, A. J.; Adams, J. H., Jr.; Beahm, L. P.; Fluckiger, E. O.; Kleis, T.; Kobel, E.

    1996-01-01

    The large solar energetic particle (SEP) events and simultaneous large geomagnetic disturbances observed during October 1989 posed a significant, rapidly evolving space radiation hazard. Using data from the GOES-7, NOAA-10, IMP-8 and LDEF satellites, we determined the geomagnetic transmission, heavy ion fluences, mean Fe ionic charge state, and effective radiation hazard observed in low Earth orbit (LEO) for these SEPs. We modeled the geomagneitc transmission by tracing particles through the combination to the internal International Geomagnetic Reference Field (IGRF) and the Tsyganenko (1989) magnetospheric field models, extending the modeling to large geomagnetic disturbances. We used our results to assess the radiation hazard such very large SEP events would pose in the anticipated 52 deg inclination space station orbit.

  4. 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.

  5. Determination of hearth position of a forthcoming strong EQ using gradients and phase velocities of ULF geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Kopytenko, Yu. A.; Ismaguilov, V. S.; Hattori, K.; Hayakawa, M.

    Behavior of gradient and phase velocity vectors of ULF ( F < 1 Hz) geomagnetic disturbances was investigated for two earthquake (EQ) events in Japan in 2000 ( M > 6) and 2003 ( M = 5.8) years. The gradient and phase velocity vectors were determined using the data of three high-sensitive three-component magnetic stations situated at a distance ∼5 km from each other (magnetic gradientometer). Two gradientometers were installed southeast and southwest of Tokyo at a distance ∼150 km from each other. It was found that the gradient and phase velocity values had anomaly changes 3-4 months before the strong EQs. New directions of the gradient vectors took place in the same period - the directions just to the forthcoming EQ epicenter. The directions from the forthcoming EQ epicenter arouse for the phase velocity vectors. We propose to use the gradient and phase velocity vectors of the ULF geomagnetic disturbances as important factors of the short-term prediction of strong earthquakes.

  6. Variations of total electron content during geomagnetic disturbances: A model/observation comparison

    NASA Technical Reports Server (NTRS)

    Roble, G. Lu X. Pi A. D. Richmond R. G.

    1997-01-01

    This paper studies the ionospheric response to major geomagnetic storm of October 18-19, 1995, using the thermosphere-ionosphere electrodynamic general circulation model (TIE-GCM) simulations and the global ionospheric maps (GIM) of total electron content (TEC) observations from the Global Positioning System (GPS) worldwide network.

  7. Geomagnetic disturbances may be environmental risk factor for multiple sclerosis: an ecological study of 111 locations in 24 countries

    PubMed Central

    2012-01-01

    Background We noticed that a hypothesis based on the effect of geomagnetic disturbances (GMD) has the ability to explain special features of multiple sclerosis (MS). Areas around geomagnetic 60 degree latitude (GM60L) experience the greatest amount of GMD. The easiest way to evaluate our hypothesis was to test the association of MS prevalence (MSP) with angular distance to geomagnetic 60 degree latitude (AMAG60) and compare it with the known association of MS with geographical latitude (GL). We did the same with angular distance to geographic 60 degree latitude (AGRAPH60) as a control. Methods English written papers with MSP keywords, done in Europe (EUR), North America (NA) or Australasia (AUS) were retrieved from the PubMed. Geomagnetic coordinates were determined for each location and AMAG60 was calculated as absolute value of numerical difference between its geomagnetic latitude from GM60L. By an ecological study with using meta-regression analyses, the relationship of MSP with GL, AMAG60 and AGRAPH60 were evaluated separately. MSP data were weighted by square root of number of prevalent cases. Models were compared by their adjusted R square (AR2) and standard error of estimate (SEE). Results 111 MSP data were entered in the study. In each continent, AMAG60 had the best correlation with MSP, the largest AR2 (0.47, 0.42 and 0.84 for EUR, NA and AUS, respectively) and the least SEE. Merging both hemispheres data, AMAG60 explained 56% of MSP variations with the least SEE (R = 0.75, AR2 = 0.56, SEE = 57), while GL explained 17% (R = 0.41, AR2 = 0.17, SEE = 78.5) and AGRAPH60 explained 12% of that variations with the highest SEE (R = 0.35, AR2 = 0.12, SEE = 80.5). Conclusions Our results confirmed that AMAG60 is the best describer of MSP variations and has the strongest association with MSP distribution. They clarified that the well-known latitudinal gradient of MSP may be actually a gradient related to GM60L. Moreover, the

  8. Superposed epoch analysis and storm statistics from 25 years of the global geomagnetic disturbance index, USGS-Dst

    USGS Publications Warehouse

    Gannon, J.L.

    2012-01-01

    Statistics on geomagnetic storms with minima below -50 nanoTesla are compiled using a 25-year span of the 1-minute resolution disturbance index, U.S. Geological Survey Dst. A sudden commencement, main phase minimum, and time between the two has a magnitude of 35 nanoTesla, -100 nanoTesla, and 12 hours, respectively, at the 50th percentile level. The cumulative distribution functions for each of these features are presented. Correlation between sudden commencement magnitude and main phase magnitude is shown to be low. Small, medium, and large storm templates at the 33rd, 50th, and 90th percentile are presented and compared to real examples. In addition, the relative occurrence of rates of change in Dst are presented.

  9. Solar large-scale positive polarity magnetic fields and geomagnetic disturbances

    NASA Technical Reports Server (NTRS)

    Bumba, V.

    1972-01-01

    Unlike the negative polarity solar magnetic field large-scale regular features that correlate with enhanced solar activity regions, the positive polarity regular formations formed in the weak and old background magnetic fields seem to correlate well with geomagnetically enhanced periods of time (shifted for 4 days), which means that they seem to be the source of the quiet solar wind. This behavior of the large intervals of heliographic longitude with prevailing positive polarity fields may be followed to the end of the 18th cycle, during the declining part of the 19th cycle, and during the first half of the present 20th cycle of solar activity.

  10. Space Weather, Geomagnetic Disturbances and Impact on the High-Voltage Transmission Systems

    NASA Technical Reports Server (NTRS)

    Pullkkinen, A.

    2011-01-01

    Geomagnetically induced currents (GIC) affecting the performance of high-voltage power transmission systems are one of the most significant hazards space weather poses on the operability of critical US infrastructure. The severity of the threat was emphasized, for example, in two recent reports: the National Research Council (NRC) report "Severe Space Weather Events--Understanding Societal and Economic Impacts: A Workshop Report" and the North American Electric Reliability Corporation (NERC) report "HighImpact, Low-Frequency Event Risk to the North American Bulk Power System." The NRC and NERC reports demonstrated the important national security dimension of space weather and GIC and called for comprehensive actions to forecast and mitigate the hazard. In this paper we will give a brief overview of space weather storms and accompanying geomagnetic storm events that lead to GIC. We will also review the fundamental principles of how GIC can impact the power transmission systems. Space weather has been a subject of great scientific advances that have changed the wonder of the past to a quantitative field of physics with true predictive power of today. NASA's Solar Shield system aimed at forecasting of GIC in the North American high-voltage power transmission system can be considered as one of the ultimate fruits of those advances. We will review the fundamental principles of the Solar Shield system and provide our view of the way forward in the science of GIC.

  11. Statistical Study of Strong and Extreme Geomagnetic Disturbances and Solar Cycle Characteristics

    NASA Astrophysics Data System (ADS)

    Kilpua, E. K. J.; Olspert, N.; Grigorievskiy, A.; Käpylä, M. J.; Tanskanen, E. I.; Miyahara, H.; Kataoka, R.; Pelt, J.; Liu, Y. D.

    2015-06-01

    We study the relation between strong and extreme geomagnetic storms and solar cycle characteristics. The analysis uses an extensive geomagnetic index AA data set spanning over 150 yr complemented by the Kakioka magnetometer recordings. We apply Pearson correlation statistics and estimate the significance of the correlation with a bootstrapping technique. We show that the correlation between the storm occurrence and the strength of the solar cycle decreases from a clear positive correlation with increasing storm magnitude toward a negligible relationship. Hence, the quieter Sun can also launch superstorms that may lead to significant societal and economic impact. Our results show that while weaker storms occur most frequently in the declining phase, the stronger storms have the tendency to occur near solar maximum. Our analysis suggests that the most extreme solar eruptions do not have a direct connection between the solar large-scale dynamo-generated magnetic field, but are rather associated with smaller-scale dynamo and resulting turbulent magnetic fields. The phase distributions of sunspots and storms becoming increasingly in phase with increasing storm strength, on the other hand, may indicate that the extreme storms are related to the toroidal component of the solar large-scale field.

  12. Gravity anomalies without geomagnetic disturbances interfere with pigeon homing--a GPS tracking study.

    PubMed

    Blaser, Nicole; Guskov, Sergei I; Entin, Vladimir A; Wolfer, David P; Kanevskyi, Valeryi A; Lipp, Hans-Peter

    2014-11-15

    The gravity vector theory postulates that birds determine their position to set a home course by comparing the memorized gravity vector at the home loft with the local gravity vector at the release site, and that they should adjust their flight course to the gravity anomalies encountered. As gravity anomalies are often intermingled with geomagnetic anomalies, we released experienced pigeons from the center of a strong circular gravity anomaly (25 km diameter) not associated with magnetic anomalies and from a geophysical control site, equidistant from the home loft (91 km). After crossing the border zone of the anomaly--expected to be most critical for pigeon navigation--they dispersed significantly more than control birds, except for those having met a gravity anomaly en route. These data increase the credibility of the gravity vector hypothesis. PMID:25392461

  13. Two types of ion energy dispersions observed in the nightside auroral regions during geomagnetically disturbed periods

    NASA Astrophysics Data System (ADS)

    Hirahara, M.; Mukai, T.; Nagai, T.; Kaya, N.; Hayakawa, H.; Fukunishi, H.

    1996-04-01

    The Akebono satellite has observed two types of energy dispersion signatures of discrete ion precipitation event in the nightside auroral regions during active geomagnetic conditions. The charged particle experiments and electric and magnetic field detectors on board Akebono provide us with essential clues to characterize the source regions and acceleration and/or injection processes associated with these two types of ion signatures. The magnetic field data obtained simultaneously by the geosynchronous GOES 6 and 7 satellites and the ground magnetograms are useful to examine their relationships with geomagnetic activity. Mass composition data and pitch angle distributions show that different sources and processes should be attributed to two types (Types I and II) of energy dispersion phenomena. Type I consists of multiple bouncing ion clusters constituted by H+. These H+ clusters tend to be detected at the expansion phase of substorms and have characteristic multiple energy-dispersed signatures. Type II consists of O+ energy dispersion(s), which is often observed at the recovery phase. It is reasonable to consider that the H+ clusters of Type I are accelerated by dipolarization at the equator, are injected in the field-aligned direction, and bounce on closed field lines after the substorm onset. We interpret these multiple energy dispersion events as mainly due to the time-of-flight (TOF) effect, although the convection may influence the energy-dispersed traces. Based of the TOF model, we estimate the source distance to be 20-30 RE along the field lines. On the other hand, the O+ energy dispersion of Type II is a consequence of reprecipitation of terrestrial ions ejected as an upward flowing ion (UFI) beam from the upper ionosphere by a parallel electrostatic potential difference. The O+ energy dispersion is induced by the E×B drift during the field-aligned transport from the source region to the observation point.

  14. Investigation of geomagnetic disturbances (F=1-5 Hz) before strong EQs in Kamchatka region

    NASA Astrophysics Data System (ADS)

    Kopytenko, Y.; Ismaguilov, V.; Schekotov, A.; Molchanov, O.; Hayakawa, M.

    2007-05-01

    Regular observations of ULF electromagnetic disturbances at st. Karymshino in seismic active zone of Kamchatka peninsula were carried out by induction three-component high-sensitive magnetometer during 2001- 2003 years. Five seismic active periods with strong earthquakes (M>5) were displayed during this period. These EQs occurred at the Pacific at 20-60 km depth at 100-140 km distances to the East from the st. Karymshino. Analysis of normalized dynamic power spectra of data of high-sensitive (0.2 pT/sqrt(Hz)) three- component induction magnetometer achieved a significant disorder of daily variation and increasing of the magnetic disturbance intensities (from 0.2 to ~ 1 pT) in the whole investigated frequency range (1 - 5 Hz). The anomaly intensity increasing was observed during the 12-18 hours before main seismic shocks. Maximum of the increasing occurred during 4-6 hours before the EQs. A sharp decreasing of the magnetic disturbance intensities was observed 2-4 hours before the EQs. We suppose that physical processes in a hearth of forthcoming EQ lead to an irreversible avalanche-like formation of cracks and stimulation of the ULF electromagnetic disturbances.

  15. Geomagnetic Dependence of Medium Scale Traveling Ionospheric Disturbances (MSTIDs) Observed by Mid- and High- Latitude SuperDARN Radars

    NASA Astrophysics Data System (ADS)

    Frissell, N. A.; Baker, J. B.; Ruohoniemi, J.; Miller, E.; West, M.; Bristow, W. A.

    2013-12-01

    Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are wave-like perturbations of the F-region ionosphere with horizontal wavelengths on the order of 100-250 km and periods between ~15 - 60 min. They are generally thought to be the ionospheric manifestation of Atmospheric Gravity Waves (AGWs). High-latitude MSTIDs have been studied using SuperDARN radars for many years, and have typically been attributed to auroral sources propagated by the Earth Reflected Wave (ERW) mode. Tropospheric sources and earthquakes are also known to be sources of MSTIDs. The goal of this study is to see if high- and mid- latitude MSTIDs share the same source region. Observations of MSTIDs using both mid- and high- latitude SuperDARN radars are presented. A case study using MSTIDs observed at the high latitude Goose Bay Radar (GBR) and the midlatitude Blackstone Radar (BKS) suggest that the auroral source is more likely for GBR than for BKS. BKS radar data from June 2010 - June 2011 were searched for signatures of MSTIDs. Statistics of propagation direction and wavelength for each event are used to suggest MSTID sources. Results show that MSTIDs are observed at BKS primarily in the fall/winter months, which is consistent with previously published results for high latitude stations. Distributions of MSTID occurrence organized by geomagnetic parameters Kp, SYM-H, and AE are presented to investigate MSTID dependence on geomagnetic activity at BKS. No correlation is found between these parameters and midlatitude MSTID occurrence, which suggests that high- and mid-latitude MSTIDs have different sources.

  16. Assessing the validity of station location assumptions made in the calculation of the geomagnetic disturbance index, Dst

    USGS Publications Warehouse

    Gannon, Jennifer

    2012-01-01

    In this paper, the effects of the assumptions made in the calculation of the Dst index with regard to longitude sampling, hemisphere bias, and latitude correction are explored. The insights gained from this study will allow operational users to better understand the local implications of the Dst index and will lead to future index formulations that are more physically motivated. We recompute the index using 12 longitudinally spaced low-latitude stations, including the traditional 4 (in Honolulu, Kakioka, San Juan, and Hermanus), and compare it to the standard United States Geological Survey definitive Dst. We look at the hemisphere balance by comparing stations at equal geomagnetic latitudes in the Northern and Southern hemispheres. We further separate the 12-station time series into two hemispheric indices and find that there are measurable differences in the traditional Dst formulation due to the undersampling of the Southern Hemisphere in comparison with the Northern Hemisphere. To analyze the effect of latitude correction, we plot latitudinal variation in a disturbance observed during the year 2005 using two separate longitudinal observatory chains. We separate these by activity level and find that while the traditional cosine form fits the latitudinal distributions well for low levels of activity, at higher levels of disturbance the cosine form does not fit the observed variation. This suggests that the traditional latitude scaling is insufficient during active times. The effect of the Northern Hemisphere bias and the inadequate latitude scaling is such that the standard correction underestimates the true disturbance by 10–30 nT for storms of main phase magnitude deviation greater than 150 nT in the traditional Dst index.

  17. Dayside Mid-Latitude F-Region Enhancements During Small or Moderate Geomagnetic Disturbances

    NASA Astrophysics Data System (ADS)

    David, M.; Sojka, J. J.

    2009-12-01

    We have used the SPIDR internet resource to collect F-region peak density data from 217 ionosonde stations, between the years of 1957 (IGY) and 2008. The stations are located around the globe, with a distribution that is far from uniform; there is especially a concentration in Europe, with quite a few in Russia, as well as North America. In our recent work at Utah State University and University of Texas Dallas [Heelis et al 2009; Sojka et al 2009], we carried out modeling studies showing how an electric field of magnetospheric origin, if expanded to mid- or low-latitudes during a storm period, can be responsible for large increases in the dayside TEC. Such an electric field may be of small magnitude, just 1 mV/m at 50 deg magnetic latitude, and still have a large effect. The enhancements created in this way can result in very steep density gradients, as much as 1 TECu per km, in the dayside ionosphere. In the present study, with a wealth of ionosonde data at our disposal, we focus on periods of small or moderate disturbance, for two reasons. First is the fact that, contrary to what is often assumed, a small disturbance is often sufficient to create large enhancements; the data does not reveal a strong correlation between the magnitude of the positive storm effect and the storm intensity as indicated by the drop in the Dst index. Second, during large-scale storms or super-storms, the data often presents a seemingly haphazard distribution of effects, stemming from the fact that many large storms do not have a clear-cut profile of onset and recovery. Our intention is to take a broad view of small-to-moderate storm periods in general, with particular attention being paid to the longitudinal distribution of positive storm effects. We find that for mild disturbances having a clear onset time and recovery phase, there is often a marked geographical coherence in the distribution of storm effects. As an example, a small storm that occurred on 15 Jan 1972, in which Dst

  18. If ionospheric and geomagnetic disturbances observed before strong earthquakes may result from simultaneous impact of space weather on all geospheres including solid earth

    NASA Astrophysics Data System (ADS)

    Khachikyan, Galina

    2016-07-01

    It is revealed in previous decades that ionospheric disturbances precede strong earthquakes, thus, the ionospheric precursors of strong earthquakes are now under developing [Pulinets and Boyarchuk, 2004]. Simultaneously, it is revealed that strong earthquakes may be preceded by geomagnetic disturbances as well, as a result, the geomagnetic variations, for example, in the ULF band, are considered now as precursory signals [Fraser-Smith, 1990, doi/10.1029/GL017i009p01465]. At the same time, there is currently no reliable theory nor for ionospheric or to magnetic precursors of earthquakes. Moreover, several researches have reexamined some of above results and concluded that observed magnetic disturbances before strong earthquakes could be generated by other sources, such as global magnetic activity [e.g. Campbell, 2009, doi/10.1029/2008JA013932], and that ionospheric anomalies can also be an effect of the increase of the global magnetic activity [e. g. Masci and Thomas, 2015, doi:10.1002/2015RS005734]. Taking into account such conclusions, one may suggest that the observed ionospheric and geomagnetic disturbances before strong earthquakes might be due to simultaneous influence of a space weather on the complicated surrounding system including the solid earth. This report presents some statistical results to prove such suggestion. In particular, it is shown [Khachikyan et al., 2012, doi:10.4236/ijg.2012.35109] that maximal possible earthquake magnitude (seismic potential) can be determined, in first approximation, on the base of geomagnetic Z-component measured in the Geocentric Solar Magnetosphere (GSM) coordinate system, in which the space weather impact on the earth's environment, due to reconnection of the solar wind magnetic field with the earth's magnetic field, is more ordered.

  19. Study of geomagnetic disturbances and ring current variability during storm and quiet times using wavelet analysis and ground-based magnetic data from multiple stations

    NASA Astrophysics Data System (ADS)

    Xu, Zhonghua

    The magnetosphere-ionosphere contains a number of current systems. These currents vary on a wide range of spatial and temporal scales and physically couple with each other. To study the complicated behaviors of these coupled current systems, the ground-based magnetometer has been a useful tool, but the recorded magnetometer data are always multi-scaled and intermittent due to the nature of these current systems. To distinguish these geomagnetic effects with multiple temporal and frequency scales, the wavelet analysis technique is especially suitable because of its special abilities of presenting information in both temporal and frequency domains. In this dissertation, the geomagnetic disturbances and the ring current variability during storm and quiet times are studied by using wavelet analysis and ground-based magnetic data from multiple stations. The first part of this dissertation investigates the strengths of applying the wavelet procedure to geomagnetic data for ring current study during storm and quiet periods. The second part of this dissertation characterizes the geomagnetic effects caused by symmetric and asymmetric components of ring currents during storm and quiet times by applying wavelet analysis to geomagnetic data from multiple stations. The third part of this dissertation studies the spatial variability of the symmetric ring current by applying the wavelet analysis technique to multiple components of magnetic data from multiple stations. The results show the unique strengths of the wavelet method allow us to quantitatively distinguish the geomagnetic effects on ring current variations from other M-I current systems. The unique strengths of wavelet method also allow us to separate the magnetic effects of the symmetric ring current from those caused by the asymmetric ring current. Quantitative information of the spatial variability of the ring currents is essential for understanding the dynamics of the ring currents, as well as the magnetic storm

  20. Geomagnetic disturbances and pulsations as a high-latitude response to considerable alternating IMF Variations during the magnetic storm recovery phase (Case study: May 30, 2003)

    NASA Astrophysics Data System (ADS)

    Levitin, A. E.; Kleimenova, N. G.; Gromova, L. I.; Antonova, E. E.; Dremukhina, L. A.; Zelinsky, N. R.; Gromov, S. V.; Malysheva, L. M.

    2015-11-01

    Features of high-latitude geomagnetic disturbances during the magnetic storm ( Dst min =-144 nT) recovery phase were studied based on the observations on the Scandinavian profile of magnetometers (IMAGE). Certain non-typical effects that occur under the conditions of large positive IMF Bz values (about +20-25 nT) and large negative IMF By values (to-20 nT) were revealed. Thus, an intense (about 400 nT) negative bay in the X component of the magnetic field (the polar electrojet, PE) was observed in the dayside sector at geomagnetic latitudes higher than 70°. As the IMF B y reverses its sign from negative to positive, the bay in the X component was replaced by the bay in the Y component. The possible distribution of the fieldaligned currents of the NBZ system was analyzed based on the CHAMP satellite data. The results were compared with the position of the auroral oval (the OVATION model) and the ion and electron flux observations on the DMSP satellite. Analysis of the particle spectra indicated that these spectra correspond to the auroral oval dayside sector crossings by the satellite, i.e., to the dayside projection of the plasma ring surrounding the Earth. Arguments are presented for the assumption that the discussed dayside electrojet ( PE) is localized near the polar edge of the dayside auroral oval in a the closed magnetosphere. The features of the spectral and spatial dynamics of intense Pc5 geomagnetic pulsations were studied in this time interval. It was established that the spectrum of high-latitude (higher than ~70°) pulsations does not coincide with the spectrum of fluctuations in the solar wind and IMF. It was shown that Pc5 geomagnetic pulsations can be considered as resonance oscillations at latitudes lower than 70° and apparently reflect fluctuations in turbulent sheets adjacent to the magnetopause (the low-latitude boundary layer, a cusp throat) or in a turbulent magnetosheath at higher latitudes.

  1. Effects of Meteorological Variability on the Thermosphere-Ionosphere System during the Moderate Geomagnetic Disturbed January 2013 Period As Simulated By Time-GCM

    NASA Astrophysics Data System (ADS)

    Maute, A. I.; Hagan, M. E.; Richmond, A. D.; Liu, H.; Yudin, V. A.

    2014-12-01

    The ionosphere-thermosphere system is affected by solar and magnetospheric processes and by meteorological variability. Ionospheric observations of total electron content during the current solar cycle have shown that variability associated with meteorological forcing is important during solar minimum, and can have significant ionospheric effects during solar medium to maximum conditions. Numerical models can be used to study the comparative importance of geomagnetic and meterological forcing.This study focuses on the January 2013 Stratospheric Sudden Warming (SSW) period, which is associated with a very disturbed middle atmosphere as well as with moderately disturbed solar geomagntic conditions. We employ the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) with a nudging scheme using Whole-Atmosphere-Community-Climate-Model-Extended (WACCM-X)/Goddard Earth Observing System Model, Version 5 (GEOS5) results to simulate the effects of the meteorological and solar wind forcing on the upper atmosphere. The model results are evaluated by comparing with observations e.g., TEC, NmF2, ion drifts. We study the effect of the SSW on the wave spectrum, and the associated changes in the low latitude vertical drifts. These changes are compared to the impact of the moderate geomagnetic forcing on the TI-system during the January 2013 time period by conducting numerical experiments. We will present select highlights from our study and elude to the comparative importance of the forcing from above and below as simulated by the TIME-GCM.

  2. Overview of the solar and interplanetary phenomena leading to the major geomagnetic disturbance on 24 March 1991

    SciTech Connect

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

    1996-07-01

    Solar activity associated with NOAA Region 6555 was unusually high during its transit across the solar disk in March 1991. A major and very impulsive solar flare with soft X-ray onset at 2242 UT occurred on 22 March. This 3B, X9.4 flare was accompanied by strong solar gamma ray emission and the type of radio emission often used as coronal mass ejection (CME) proxies. Approximately four hours later, a series of major flares gave rise to long duration X-ray emission but without the radio signatures used as CME indicators. Although these major solar events were similar to other activity this solar cycle, the combination of extremely powerful solar activity, a major solar particle event and rapidly moving interplanetary shocks combined to give one of the most intense geomagnetic storms of this solar cycle. There were two momentum impulses to the magnetosphere. The first at 0342 UT on 24 March is associated with the rapidly moving interplanetary shock. The second at 1920 UT is associated with the major increase in geomagnetic activity. The solar and interplanetary events that preceded the geomagnetic storm are discussed together with the effects of the storm on the cosmic ray intensity at the earth. Finally, using data from historical events such as those in July 1959 and November 1960, we speculate on the combination of solar and interplanetary circumstances that lead to increased radiation in the trapped radiation belts. {copyright} {ital 1996 American Institute of Physics.}

  3. OI 630.0 nm all-sky image observations of medium-scale traveling ionospheric disturbances at geomagnetic conjugate points

    NASA Astrophysics Data System (ADS)

    Stefanello, M. B.; Muella, M. T. A. H.; Amorim, D. C. M.; Machado, C. S.; Bageston, J. V.; Pimenta, A. A.; Martinis, C.; Sullivan, C.; Bittencourt, J. A.; Schuch, N. J.

    2015-06-01

    This paper presents a medium-scale traveling ionospheric disturbance (MSTID) occurrence detected through the OI 630.0 nm emission all-sky images, obtained by ground-based imaging systems installed at close geomagnetic conjugate locations: one at the Southern Space Observatory-SSO/CRS/INPE-MCTI, (29.4°S, 53.8°W), in Sao Martinho da Serra, RS, Brazil, and another at the Arecibo Observatory (18.3°N, 66.7°W), in Puerto Rico. The images obtained show the optical signature of MSTIDs (low intensity regions of 630.0 nm airglow emission), propagating simultaneously in both hemispheres, during geomagnetically quiet conditions (Kp<3). Observations using digital ionosonde installed at Falkland Islands (51.4°S, 57.5°W) and Ramey, Puerto Rico (18.5°N, 67.1°W) show an abrupt upward motion of the ionospheric F region plasma and the occurrence of frequency-type spread-F that could be related to the MSTIDs observed optically. Using Global Positioning System (GPS) receiver data, we also obtained the rate of the Total Electronic Content (TEC) change (ROT) for two geomagnetically conjugated sites-Santa Maria (29.7°S, 53.7°W) and Virgin Islands (17.7° N, 64.7°W). The analysis of TEC allows us to identify an irregular ionization in the F layer associated with the passage of an MSTID. The possible effects of the South America Magnetic Anomaly (SAMA) on the electrodynamic processes that control the inter-hemispheric coupling that give origin to the conjugate MSTIDs are highlighted and discussed.

  4. Evidence of low-latitude daytime large-scale traveling ionospheric disturbances observed by high-frequency multistatic backscatter sounding system during a geomagnetically quiet period

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Zhao, Zhengyu; Yang, Guobin; Chen, Gang; Hu, Yaogai; Zhang, Yuannong

    2012-06-01

    Observations from the high-frequency multistatic backscatter sounding radars on a geomagnetically quiet day (minimum Dst = -14 nT) captured the anti-equatorward propagation of daytime large-scale traveling ionospheric disturbance (LSTID) at the low-latitude regions. The observed LSTID was characterized approximately by a meridional propagation speed of 347 ± 78 m/s and azimuthal angle of -4.7 ± 27.6° (counterclockwise from north), with a period of 76 min and a wavelength of 1583 ± 354 km by means of maximum entropy cross-spectral analysis. Vertical phase velocity was also evaluated to be <˜42 m/s through the Doppler measurements. These results provide evidence that the low-latitude ionosphere can undergo large-scale perturbations even under geomagnetically quiet conditions. We suggest that this observed LSTID could be due to the secondary gravity waves from thermospheric body forces created from the dissipation of primary gravity waves from deep tropospheric convection.

  5. Lack of evidence for meteorological effects on infradian dynamics of testosterone

    NASA Astrophysics Data System (ADS)

    Celec, Peter; Smreková, Lucia; Ostatníková, Daniela; Čabajová, Zlata; Hodosy, Július; Kúdela, Matúš

    2009-09-01

    Climatic factors are known to influence the endocrine system. Previous studies have shown that circannual seasonal variations of testosterone might be partly explained by changes in air temperature. Whether infradian variations are affected by meteorological factors is unknown. To analyze possible effects of meteorological parameters on infradian variations of salivary testosterone levels in both sexes, daily salivary testosterone levels were measured during 1 month in 14 men and 17 women. A correlation analysis between hormonal levels and selected meteorological parameters was performed. The results indicate that high testosterone levels are loosely associated with cold, sunny and dry weather in both sexes. However, only the correlations between testosterone and air temperature (men) and actual cloudiness (women) were statistically significant ( p < 0,05). Although some correlations reached the level of statistical significance, the effects of selected meteorological parameters on salivary testosterone levels remain unclear. Further longer-term studies concentrating on air temperature, cloudiness and average relative humidity in relation to the sex hormone axis are needed.

  6. Equatorial plasma depletions observed by the DMSP F13 satellite near dawn during geomagnetic disturbances in a solar minimum

    NASA Astrophysics Data System (ADS)

    Kim, V. P.; Min, K. W.; Hegai, V. V.

    2015-01-01

    We report on in situ measurements of equatorial plasma depletions in the dawn sector from the DMSP F13 satellite during magnetic disturbances which occurred within the solar minimum period of 1995-1996. Examples are given when DMSP F13 observed prominent pre-sunrise depletions associated with weak magnetic disturbances, while the most severe magnetic storms of the period showed only small amplitude depletions of plasma density. Our results indicate that the depletions were observed within about two third of the magnetically perturbed days with the negative maximum excursions of SYM-H less than -40 nT at any season and at various longitudes. Commonly, the depletions appear following the negative SYM-H peaks in the recovery phase of the magnetic disturbances. We discuss the roles of corotating evening depletions and near-dawn effects of the prompt penetration overshielding and the disturbance dynamo eastward electric fields as sources for the reported depletions.

  7. Daytime geomagnetic disturbances at high latitudes during a strong magnetic storm of June 21-23, 2015: The storm initial phase

    NASA Astrophysics Data System (ADS)

    Gromova, L. I.; Kleimenova, N. G.; Levitin, A. E.; Gromov, S. V.; Dremukhina, L. A.; Zelinskii, N. R.

    2016-05-01

    The high-latitude geomagnetic effects of an unusually long initial phase of the largest magnetic storm ( SymH ~-220 nT) in cycle 24 of the solar activity are considered. Three interplanetary shocks characterized by considerable solar wind density jumps (up to 50-60 cm-3) at a low solar wind velocity (350-400 km/s) approached the Earth's magnetosphere during the storm initial phase. The first two dynamic impacts did not result in the development of a magnetic storm, since the IMF Bz remained positive for a long time after these shocks, but they caused daytime polar substorms (magnetic bays) near the boundary between the closed and open magnetosphere. The magnetic field vector diagrams at high latitudes and the behaviour of high-latitude long-period geomagnetic pulsations ( ipcl and vlp) made it possible to specify the dynamics of this boundary position. The spatiotemporal features of daytime polar substorms (the dayside polar electrojet, PE) caused by sudden changes in the solar wind dynamic pressure are discussed in detail, and the singularities of ionospheric convection in the polar cap are considered. It has been shown that the main phase of this two-stage storm started rapidly developing only when the third most intense shock approached the Earth against a background of large negative IMF Bz values (to-39 nT). It was concluded that the dynamics of convective vortices and the related restructing of the field-aligned currents can result in spatiotemporal fluctuations in the closing ionospheric currents that are registered on the Earth's surface as bay-like magnetic disturbances.

  8. Influence of Solar-Geomagnetic Disturbances on SABER Measurements of 4.3 Micrometer Emission and the Retrieval of Kinetic Temperature and Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Mertens, Christopher J.; Winick, Jeremy R.; Picard, Richard H.; Evans, David S.; Lopez-Puertas, Manuel; Wintersteiner, Peter P.; Xu, Xiaojing; Mlynczak, Martin G.; Russell, James M., III

    2008-01-01

    Thermospheric infrared radiance at 4.3 micrometers is susceptible to the influence of solar-geomagnetic disturbances. Ionization processes followed by ion-neutral chemical reactions lead to vibrationally excited NO(+) (i.e., NO(+)(v)) and subsequent 4.3 micrometer emission in the ionospheric E-region. Large enhancements of nighttime 4.3 m emission were observed by the TIMED/SABER instrument during the April 2002 and October-November 2003 solar storms. Global measurements of infrared 4.3 micrometer emission provide an excellent proxy to observe the nighttime E-region response to auroral dosing and to conduct a detailed study of E-region ion-neutral chemistry and energy transfer mechanisms. Furthermore, we find that photoionization processes followed by ion-neutral reactions during quiescent, daytime conditions increase the NO(+) concentration enough to introduce biases in the TIMED/SABER operational processing of kinetic temperature and CO2 data, with the largest effect at summer solstice. In this paper, we discuss solar storm enhancements of 4.3 micrometer emission observed from SABER and assess the impact of NO(+)(v) 4.3 micrometer emission on quiescent, daytime retrievals of Tk/CO2 from the SABER instrument.

  9. 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

  10. 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

    Geomagnetic variations of partly interplanetary origin, with cyclic signatures in human affairs and pathology include the incidence of various diseases, regarding which this study of healthy subjects attempted to determine an underlying mechanism by worldwide archival and physiological monitoring, notably of heart rate variability (HRV). In the past half-century, the possible health and other hazards of natural, solar variability-driven temporal variations in the earth's magnetic field have become a controversial subject in view of the inconsistent results. Some well-documented claims of associations between geomagnetic storms and myocardial infarction or stroke have been rejected by a study based on more comprehensive data analyzed by rigorous methods - covering, however, only part of a solar cycle in only part of a hemisphere. It seems possible that inter-solar cycle and geographic variability, if not geographic differences, may account for discrepancies. Herein, we examine the start of a planetary study on any influence of geomagnetic disturbances that are most pronounced in the auroral oval, on human HRV. The magnetic field variations exhibit complex spectra and include the frequency band between 0.001-10 Hz, which is regarded as ultra-low frequency by physicists. Since the 'ultra-low-frequency' range, like other endpoints used in cardiology, refers to much higher frequencies than the about-yearly changes that are here shown to play a role in environmental-organismic interactions revealed by HRV, the current designations used in cardiology are all placed in quotation marks to indicate the need for possible revision. Whether or not this suggestion has an immediate response, we have pointed to a need for the development of instrumentation and software that renders the assessment of circadian, infradian and even infra-annual (truly low frequency) modulations routinely feasible. HRV was examined on the basis of nearly continuous 7-day records by ECG between

  11. 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.

  12. 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.

  13. Geomagnetic field effects of the Chelyabinsk meteoroid

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.

    2014-09-01

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

  14. 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

  15. Geomagnetically Induced Currents, a space weather hazard. Case study - Europe under intense geomagnetic storms of the solar cycle 23

    NASA Astrophysics Data System (ADS)

    Dobrica, V.; Demetrescu, Cr.; Stefan, C.; Greculeasa, R.

    2016-05-01

    The interaction of the solar wind and heliospheric magnetic field with the magnetosphere and ionosphere results in variations of the geomagnetic field that induce hazardous electric currents in grounded technological systems (electric power and hydrocarbon transportation networks), the so-called geomagnetically induced currents (GICs). In order to evaluate the hazard induced on the European continent, we present a study of the surface electric field induced by 16 intense (Dst < -150 nT) geomagnetic storms, based on the analysis of the geomagnetic records from the European network of observatories, study that tend to solve the geophysical part of the problem. The evolution during storm development and the sources of the disturbance field are explored in case of the largest geomagnetic storm in the cycle 23 (Dst = -422 nT, November 20-21, 2003), and the geographical distribution of the maximum induced surface geoelectric field over Europe by the 16 storms considered in the study is presented. As source proxies, the Dst geomagnetic index, showing the disturbed field produced by the magnetospheric ring current at the geomagnetic equator, the AL geomagnetic index, showing the disturbed field produced by the ionospheric electrojet at auroral latitude, and the PC geomagnetic index, showing the disturbed field produced by the polar cap current, were examined.

  16. 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.

  17. Geomagnetic storm forecasts and the power industry

    NASA Astrophysics Data System (ADS)

    Kappenman, John G.; Zanetti, Lawrence J.; Radasky, William A.

    There is a well-recognized link between solar activity, geomagnetic disturbances, and disruptions to man-made systems such as power grids, satellites, communications, and defense systems. As technology evolves, these systems become more susceptible to magnetic disturbances than their counterparts of previous solar cycles. Analysis suggests that these vulnerabilities will continue and perhaps even increase as these systems continue to evolve.Geomagnetic disturbances can cause geomagnetically induced currents (GIC) to flow through the power system, entering and exiting the many grounding points on a transmission network. This is generally of most concern at the latitudes of the northern United States, Canada, and Scandinavia, for example, but regions much farther south are also affected during intense magnetic storms.

  18. Ionospheric Response to Geomagnetic Activity during 2007-2009 Solar Minimum

    NASA Astrophysics Data System (ADS)

    Chen, Yiding; Liu, Libo; Huijun Le, lake709.; Wan, Weixing

    The significant effect of weaker geomagnetic activity on ionospheric day-to-day variability during 2007-2009 solar minimum was highlighted by investigating the response of global electron content (GEC) to geomagnetic activity index Ap. A case distinctly manifests the modulation of recurrent weaker geomagnetic disturbance on GEC during the solar minimum. Statistical analyses indicate that the effect of weaker geomagnetic activity on GEC day-to-day variability is significant during 2007-2009, even under relatively quiet geomagnetic activity condition, while geomagnetic activity effect on GEC is not prominent during 2003-2005 solar cycle descending phase except under strong geomagnetic disturbance condition. Nevertheless, statistically the most important effect on GEC day-to-day variability during 2007-2009 comes from the factors other than geomagnetic activity and solar EUV irradiance.

  19. Ionospheric Response to Geomagnetic Activity during 2007-2009 Solar Minimum

    NASA Astrophysics Data System (ADS)

    Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing

    2014-05-01

    The significant effect of weaker geomagnetic activity on ionospheric day-to-day variability during 2007-2009 solar minimum was highlighted by investigating the response of global electron content (GEC) to geomagnetic activity index Ap. A case distinctly manifests the modulation of recurrent weaker geomagnetic disturbance on GEC during the solar minimum. Statistical analyses indicate that the effect of weaker geomagnetic activity on GEC day-to-day variability is significant during 2007-2009, even under relatively quiet geomagnetic activity condition, while geomagnetic activity effect on GEC is not prominent during 2003-2005 solar cycle descending phase except under strong geomagnetic disturbance condition. Nevertheless, statistically the most important effect on GEC day-to-day variability during 2007-2009 comes from the factors other than geomagnetic activity and solar EUV irradiance.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Local geomagnetic indices and their role in space weather

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The analysis of local geomagnetic disturbances (specific longitude and latitude) have recently proved to play an important role in space weather research. Localized strong (high intensity) and impulsive (fast developed and fast recovered) geomagnetic disturbances are typically recorded at high latitudes and commonly related to field-aligned currents. These type of disturbances are also recorded, less frequently, at mid and low latitudes, representing an important hazard for technology. In order to obtain geomagnetic disturbances (geomagnetic index) from the records at a certain observatory, a baseline has to be removed. The baseline is usually determined taking into account geomagnetic secular variation and solar quiet time. At mid-latitudes the shape of the daily solar quiet component presents a strong day-to-day variability difficult to predict. In this work we present a new technique capable to determine the baseline at mid-latitudes which allows us to obtain a high resolution local geomagnetic index with the highest accuracy ever obtained at mid-latitudes.

  6. Effects of strong geomagnetic storms on Northern railways in Russia

    NASA Astrophysics Data System (ADS)

    Eroshenko, E. A.; Belov, A. V.; Boteler, D.; Gaidash, S. P.; Lobkov, S. L.; Pirjola, R.; Trichtchenko, L.

    2010-11-01

    Seventeen severe magnetic storms occurred in the period 2000 through 2005. In addition there was a major magnetic storm in March 1989. During each of these storms there was an anomaly in the operation of the system of Signalization, Centralization and Blockage (SCB) in some divisions of the high-latitude (˜58 to 64°N) Russian railways. This anomaly was revealed as false traffic light signals about the occupation of the railways. These signals on the Northern railways appeared exactly during the main phases of the strongest part of the geomagnetic storms characterized by high geomagnetic indices Dst and Kp (Ap). Moreover, the durations of these anomalies coincided with the period of the greatest geomagnetic disturbances in a given event. Geomagnetically induced currents (GICs) during significant strengthening of geomagnetic activity are concluded as the obvious reasons for such kind of anomalies.

  7. Geomagnetic field variations in seismic waves traveling across a fault

    NASA Astrophysics Data System (ADS)

    Lukishov, B. G.; Spivak, A. A.; Ter-Semenov, A. A.

    2012-01-01

    The results of regular instrumental observations over geomagnetic field variations in the zones of influence of tectonic faults during movement of seismic waves of varied intensity are presented. It has been shown that seismic waves with an amplitude more than 5-10 μm/s, traveling across the fault zone, always produced geomagnetic field variations. At weaker seismic disturbances, geomagnetic field variations are of the "glimmer" character, and the relative frequency of appearance of the effect drops as the seismic wave amplitude decreases. The quantitative dependence between the maximal value of the full vector of variations in geomagnetic field induction in a fault zone and the amplitude of the seismic disturbance has been found for the first time.

  8. 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.

  9. The equatorial electrojet during geomagnetic storms and substorms

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yosuke; Kosch, Michael J.

    2015-03-01

    The climatology of the equatorial electrojet during periods of enhanced geomagnetic activity is examined using long-term records of ground-based magnetometers in the Indian and Peruvian regions. Equatorial electrojet perturbations due to geomagnetic storms and substorms are evaluated using the disturbance storm time (Dst) index and auroral electrojet (AE) index, respectively. The response of the equatorial electrojet to rapid changes in the AE index indicates effects of both prompt penetration electric field and disturbance dynamo electric field, consistent with previous studies based on F region equatorial vertical plasma drift measurements at Jicamarca. The average response of the equatorial electrojet to geomagnetic storms (Dst<-50 nT) reveals persistent disturbances during the recovery phase, which can last for approximately 24 h after the Dst index reaches its minimum value. This "after-storm" effect is found to depend on the magnitude of the storm, solar EUV activity, season, and longitude.

  10. Intense geomagnetic storms: A study

    NASA Astrophysics Data System (ADS)

    Silbergleit, Virginia

    In the pipes and the lines of the transmission of the electrical energy, the route of the currents through them, causes a diminution of the life utility of the same one. The intense storms are studied, because these are induced quickly to the ionospheric systems that they change, obtaining great induced telluric currents (or GICs). Also the Akasofús parameter based on the time for periods of strong and moderate magnetic storms during the last 10 years is calculated. The method also standardizes the parameters of the storm: electron flow between 30-300 KeV, z component of the magnetic field (Bz), the solar Wind velocity (v), indices AE and AL. Also, the decay time of the ring current (which is different during the main and the recovery phase from of the geomagnetic disturbances) are calculated.

  11. 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.

  12. Tsunami related to solar and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2016-04-01

    ascertained by authors from 2012, have confirmed that the four strongest earthquakes (and then the four tsunami) were preceded by a clear increase of the solar wind proton density which subsequently generated perturbation of the Earth's geomagnetic field. The temporal characteristics of the proton increases and geomagnetic disturbances that preceded the four tsunami have a clear predictive significance especially in the face of recent studies on Seismic Solar Precursors (SSPs), on Interplanetary Seismic Precursors (ISPs) and on Seismic Geomagnetic Precursors (SGPs) presented by the authors in the last two years.

  13. A prediction of geomagnetic activity for solar cycle 23

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.; Ling, A. G.; Wise, J. E.; Lanzerotti, L. J.

    1999-04-01

    Using a database of 13 solar cycles of geomagnetic aa data, we obtained correlations between cycle averages of geomagnetic activity (and sunspot number) and the numbers of days with disturbance levels above certain aa thresholds. We then used a precursor-type relation to predict an average aa index of 23.1 nT for cycle 23 and inserted this average aa value into the above correlations to forecast the integral size distribution of geomagnetic activity for the new cycle. The predicted size distribution is similar to that observed for cycles 21 and 22 but most closely resembles that of solar cycle 18 (1944-1954), which was slightly smaller than cycles 21 and 22. Our prediction agrees reasonably well with the ``climatology-based'' forecast made by the intergovernmental panel tasked to predict geomagnetic activity for the coming solar cycle and is significantly different from their ``precursor-based'' prediction.

  14. 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.

  15. F layer positive response to a geomagnetic storm - June 1972

    NASA Technical Reports Server (NTRS)

    Miller, N. J.; Grebowsky, J. M.; Mayr, H. G.; Harris, I.; Tulunay, Y. K.

    1979-01-01

    A circulation model of neutral thermosphere-ionosphere coupling is used to interpret in situ spacecraft measurements taken during a topside midlatitude ionospheric storm. The data are measurements of electron density taken along the circular polar orbit of Ariel 4 at 550 km during the geomagnetically disturbed period June 17-18, 1972. It is inferred that collisional momentum transfer from the disturbed neutral thermosphere to the ionosphere was the dominant midday process generating the positive F-layer storm phase in the summer hemisphere. In the winter hemisphere the positive storm phase drifted poleward in the apparent response to magnetospheric E x B drifts. A summer F-layer positive phase developed at the sudden commencement and again during the geomagnetic main phase; a winter F-layer positive phase developed only during the geomagnetic main phase. The observed seasonal differences in both the onsets and the magnitudes of the positive phases are attributed to the interhemispheric asymmetry in thermospheric dynamics.

  16. What causes geomagnetic activity during sunspot minimum?

    NASA Astrophysics Data System (ADS)

    Kirov, B.; Asenovski, S.; Georgieva, K.; Obridko, V. N.

    2015-12-01

    It is well known that the main drivers of geomagnetic disturbances are coronal mass ejections whose number and intensity are maximum in sunspot maximum, and high speed solar wind streams from low latitude solar coronal holes which maximize during sunspot declining phase. But even during sunspot minimum periods when there are no coronal mass ejections and no low latitude solar coronal holes, there is some "floor" below which geomagnetic activity never falls. Moreover, this floor changes from cycle to cycle. Here we analyze the factors determining geomagnetic activity during sunspot minimum. It is generally accepted that the main factor is the thickness of the heliospheric current sheet on which the portion of time depends which the Earth spends in the slow and dense heliospheric current sheet compared to the portion of time it spends in the fast solar wind from superradially expanding polar coronal holes. We find, however, that though the time with fast solar wind has been increasing in the last four sunspot minima, the geomagnetic activity in minima has been decreasing. The reason is that the parameters of the fast solar wind from solar coronal holes change from minimum to minimum, and the most important parameter for the fast solar wind's geoeffectivity—its dynamic pressure—has been decreasing since cycle 21. Additionally, we find that the parameters of the slow solar wind from the heliospheric current sheet which is an important driver of geomagnetic activity in sunspot minimum also change from cycle to cycle, and its magnetic field, velocity and dynamic pressure have been decreasing during the last four minima.

  17. Geomagnetic activity effect on the global ionosphere during the 2007-2009 deep solar minimum

    NASA Astrophysics Data System (ADS)

    Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing

    2014-05-01

    In this paper the significant effect of weaker geomagnetic activity during the 2007-2009 deep solar minimum on ionospheric variability on the shorter-term time scales of several days was highlighted via investigating the response of daily mean global electron content (GEC, the global area integral of total electron content derived from ground-based GPS measurements) to geomagnetic activity index Ap. Based on a case during the deep solar minimum, the effect of the recurrent weaker geomagnetic disturbances on the ionosphere was evident. Statistical analyses indicate that the effect of weaker geomagnetic activity on GEC variations on shorter-term time scales was significant during 2007-2009 even under relatively quiet geomagnetic activity condition; daily mean GEC was positively correlated with geomagnetic activity. However, GEC variations on shorter-term time scales were poorly correlated with geomagnetic activity during the solar cycle descending phase of 2003-2005 except under strong geomagnetic disturbance condition. Statistically, the effects of solar EUV irradiance, geomagnetic activity, and other factors (e.g., meteorological sources) on GEC variations on shorter-term time scales were basically equivalent during the 2007-2009 solar minimum.

  18. Simulation Of Fluctuating Geomagnetic Index

    NASA Technical Reports Server (NTRS)

    Vedder, John; Tabor, Jill

    1993-01-01

    Mathematical model produces synthetic geomagnetic-index (ap) data including short-term fluctuations like those of real ap data. Measures geomagnetic activity computed from measurements of fluctuations in geomagnetic field taken at 12 high-latitude stations every 3 hours. Used in studies of interactions between solar wind and Earth, especially in studies of effect of geomagnetic field upon heating of thermosphere by impacts of energetic charged solar-wind particles.

  19. Range indices of geomagnetic activity

    USGS Publications Warehouse

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

    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.

  20. [Relation between microcirculation parameters and Pc3 geomagnetic pulsations].

    PubMed

    Zenchehko, T A; Poskotinova, L V; Rekhtina, A G; Zaslavskaia, R M

    2010-01-01

    An individual analysis of long-term monitoring of microcirculation parameters of nine healthy volunteers showed that an increase in the geomagnetic activity led to an increase in tissue perfusion, variability of blood flow and growth of the amplitude of neurogenic and myogenic oscillations in four volunteers. It was found that the degree of microcirculation sensitivity to the level of geomagnetic activity values with time and is proportional to its average level in the period of measurement. A comparison of frequency ranges of oscillations of blood flow and variations of the geomagnetic activity shows that neurogenic and myogenic oscillations showing the highest sensitivity to the geomagnetic activity have the same frequency as geomagnetic Pc3 pulsations. The pulsations of this frequency range are excited mainly during geomagnetic disturbances, which may explain the correlation between the microcirculation parameters and the Kp index. The relation of the amplitude-frequency characteristics of Pc3-pulsations can explain the results obtained using the alternating magnetic fields. PMID:20968090

  1. 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.

  2. Vertical total electron content and geomagnetic perturbations at mid- and sub-auroral southern latitudes during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Meza, Amalia; Andrea van Zele, María; Claudio, Brunini; Rosalía Cabassi, Iris

    2005-03-01

    Several new space geodesy techniques allow us to analyze the behavior of the vertical total electron content (VTEC) with high spatial and temporal resolution. This study is based on the VTEC computed from global positioning system (GPS) satellite signals that are recorded from observatories located at mid- and sub-auroral southern latitudes. The geomagnetic disturbances are analyzed using the Dst and AL geomagnetic indices and geomagnetic field variations which are recorded from an observatory close to one of the GPS stations and from observatories located at equivalent geomagnetic latitudes but in the Northern Hemisphere. The study is focused on two consecutive geomagnetic storms, which happened on October 4 and 5, 2000, characterized by two flips of the interplanetary magnetic field. During this perturbed period, the substorms are evidenced by the AL index and by the field variations recorded by the geomagnetic observatories. We also analyze a substorm effect that occurred during a geomagnetic storm. Variations in f0F2 are currently considered to study the geomagnetic storm effects on the ionosphere. Our results show that at mid- and subauroral southern latitudes the behavior of the VTEC evidences the “dusk” effect (positive ionospheric storm after noon) in a similar way to f0F2 variations. Similar geomagnetic conditions can be inferred from the Dst index for both geomagnetic storms but a quick rise of the VTEC and the dusk effect is only observed on the first stormy day. The positive ionospheric storm is followed by a negative phase that lasts until October 6. The second geomagnetic storm starts when the negative phase of the first ionospheric storm is still deployed and the ionosphere/plasmasphere system conditions do not allow a new positive ionospheric storm. The AL index and the geomagnetic field variations allow us to recognize the expansion phase of the substorm due to the presence of the electromagnetic wedge that couples the magnetosphere and

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. Long-period geomagnetic pulsations as solar flare precursors

    NASA Astrophysics Data System (ADS)

    Barkhatov, N. A.; Obridko, V. N.; Revunov, S. E.; Snegirev, S. D.; Shadrukov, D. V.; Sheiner, O. A.

    2016-03-01

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

  11. Geomagnetic Pulsation Amplitude and Spectrum Variations Accompanying the Ionospheric Heating by High-Power Radio waves from the Sura Facility

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.; Frolov, V. L.

    2014-10-01

    Aperiodic and quasiperiodic variations in the geomagnetic pulsation amplitude in a range of periods from 40 to 1000 s, which accompany the quasicontinuous and periodic impact on the ionospheric plasma by high-power radio waves from the SURA facility near Nizhny Novgorod (Russia) were recorded near Kharkov (Ukraine) using a magnetometer-fluxmeter. The main parameters of aperiodic and quasiperiodic disturbances of the geomagnetic field are determined. The mechanisms for generation and propagation of detected disturbances are discussed.

  12. 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

  13. Geomagnetic polarity transitions

    NASA Astrophysics Data System (ADS)

    Merrill, Ronald T.; McFadden, Phillip L.

    1999-05-01

    The top of Earth's liquid outer core is nearly 2900 km beneath Earth's surface, so we will never be able to observe it directly. This hot, dense, molten iron-rich body is continuously in motion and is the source of Earth's magnetic field. One of the most dynamic manifestations at Earth's surface of this fluid body is, perhaps, a reversal of the geomagnetic field. Unfortunately, the most recent polarity transition occurred at about 780 ka, so we have never observed a transition directly. It seems that a polarity transition spans many human lifetimes, so no human will ever witness the phenomenon in its entirety. Thus we are left with the tantalizing prospect that paleomagnetic records of polarity transitions may betray some of the secrets of the deep Earth. Certainly, if there are systematics in the reversal process and they can be documented, then this will reveal substantial information about the nature of the lowermost mantle and of the outer core. Despite their slowness on a human timescale, polarity transitions occur almost instantaneously on a geological timescale. This rapidity, together with limitations in the paleomagnetic recording process, prohibits a comprehensive description of any reversal transition both now and into the foreseeable future, which limits the questions that may at this stage be sensibly asked. The natural model for the geomagnetic field is a set of spherical harmonic components, and we are not able to obtain a reliable model for even the first few harmonic terms during a transition. Nevertheless, it is possible, in principle, to make statements about the harmonic character of a geomagnetic polarity transition without having a rigorous spherical harmonic description of one. For example, harmonic descriptions of recent geomagnetic polarity transitions that are purely zonal can be ruled out (a zonal harmonic does not change along a line of latitude). Gleaning information about transitions has proven to be difficult, but it does seem

  14. Geomagnetic survey and geomagnetic model research in China

    NASA Astrophysics Data System (ADS)

    Gu, Zuowen; Zhan, Zhijia; Gao, Jintian; Han, Wei; An, Zhenchang; Yao, Tongqi; Chen, Bin

    2006-06-01

    The geomagnetic survey at 135 stations in China were carried out in 2003. These stations are with better environmental condition and small magnetic field gradient (<5 nT/m). In the field survey, the geomagnetic declination D, the inclination I and the total intensity F were measured. Ashtech ProMark2 differential GPS (Global Positioning System) was used in measuring the azimuth, the longitude, the latitude and the elevation at these stations. The accuracy of the azimuth is 0.1'. The geomagnetic survey data were reduced using the data at geomagnetic observatories in China. The mean standard deviations of the geomagnetic reduced values are: <1.5 nT for F, <0.5' for D and I. Using the geomagnetic data which include the data at 135 stations and 35 observatories in China, and the data at 38 IGRF (International Geomagnetic Reference Field) calculation points in China's adjacent regions, the Taylor polynomial model and the spherical cap harmonic model were calculated for the geomagnetic field in China. The truncation order of the Taylor polynomial model is 5, and its original point is at 36.0°N and 104.5°E. Based on the geomagnetic anomalous values and using the method of spherical cap harmonic (SCH) analysis, the SCH model of the geomagnetic anomalous field was derived. In the SCH model, the pole of the spherical cap is at 36.0°N and 104.5°E, and the half-angle is 30°, the truncation order K= 8 is determined according to the mean square deviation between the model calculation value and the observation value, the AIC (Akaike Information Criterion) and the distribution of geomagnetic field.

  15. Study about geomagnetic variations from data recorded at Surlari Geomagnetic Observatory

    NASA Astrophysics Data System (ADS)

    Asimopolos, Laurentiu; Asimopolos, Natalia-Silvia; Sandulescu, Agata Monica; Niculici, Eugen

    2013-04-01

    This paper presents statistical and spectral analysis of data from Surlari Geomagnetic Observatory that contributing to study of geomagnetic variations. Thus were highlighted, for long series of records over several solar cycles, periodicities of 22 years and 11 years. Following the same procedures for medium recording series (multi-annual) have highlighted annual, seasonal and monthly periodicities. For shorter data series, we highlighted diurnal, semidiurnal, 8 hours and even lower periodicities. For very short series with a high sample rate and for few magnetotellurics records, we highlight different types of pulsations (Pc2 - Pc5 and Pi 2). Geomagnetic signals are the convolution product of the atomic stationary signals mono-frequential of different amplitudes associated to phenomena with a very broad band of periodicities and nondeterministic signals associated with geomagnetic disturbances and non-periodic phenomena. Among analysis processes used for discrete series of geomagnetic data with different lengths and sampling rates, can conclude the following: Moving average works as a low pass filter in frequency or high pass in time. By eliminating high frequency components (depending on mobile window size used) can be studied preferential periodicities greater than a given value. Signal linearization (using least squares) provides information on linear trend of the entire series analyzed. Thus, for the very long data series (several decades) we extracted the secular variation slope for each geomagnetic component, separately. The numeric derivative of signal versus time proved to be a very reliable indicator for geomagnetic disturbed periods. Thus, the derivative value may be increased by several orders of magnitude during periods of agitation in comparisons to calm periods. The correlation factor shows significant increases when between two time series a causal relationship exists. Variation of the correlation factor, calculated for a mobile window containing k

  16. History of the Munich-Maisach-Fürstenfeldbruck Geomagnetic Observatory

    NASA Astrophysics Data System (ADS)

    Soffel, H. C.

    2015-07-01

    The Munich-Maisach-Fürstenfeldbruck Geomagnetic Observatory is one of the observatories with the longest recordings of the geomagnetic field. It started with hourly measurements on 1 August 1840. The founder of the observatory in Munich was Johann von Lamont (1805-1879), the Director of the Royal Bavarian Astronomical Observatory. He had been stimulated to build his own observatory by the initiative of the Göttingen Magnetic Union founded in 1834 by Alexander von Humboldt (1769-1859) and Carl Friedrich Gauss (1777-1855). Before 1840 fewer than five observatories existed; the most prominent ones were those in London and Paris. At the beginning Lamont used equipment delivered by Gauss in Göttingen, but soon started to build instruments of his own design. Among them was a nonmagnetic theodolite which allowed precise geomagnetic measurements to be made also in the field. During the 1850s Lamont carried out geomagnetic surveys and produced geomagnetic maps for Germany and many other European countries. At the end of the nineteenth century accurate geomagnetic measurements in Munich became more and more disturbed by the magnetic stray fields from electric tramways and industry. During this period the quality of the data suffered and the measurements had to be interrupted several times. After a provisional solution in Maisach, a village 25 km west of Munich, a final solution could be found in the vicinity of the nearby city of Fürstenfeldbruck. Here the measurements started again on 1 January 1939. Since the 1980s the observatory has been part of INTERMAGNET, an organization providing almost real-time geomagnetic data of the highest quality.

  17. Surface electric fields for North America during historical geomagnetic storms

    USGS Publications Warehouse

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  18. 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

  19. Information Theory Approach to Evaluate the Geomagnetic and Ionospheric Response to Solar Wind Parameters

    NASA Astrophysics Data System (ADS)

    Seemala, G. K.; R, S.; Bhaskara, V.; Ramesh, D. S.

    2014-12-01

    The importance of space weather and understanding onset o geomagnetic storms is increasing day by day as the space missions increase. It is known from the ground-based and space-borne observations that a geomagnetic storm is a temporary disturbance of earth's magnetosphere caused by a solar wind and/or solar eruptions. Geomagnetic storms are more disruptive now than in the past because of our greater dependence on technical systems that can be affected by electric currents and energetic particles high in the Earth's magnetosphere. It is known that number of phenomena occurs during the space weather events; and there are many un-solved questions like solar wind coupling with magnetosphere and ionosphere, relationship between geomagnetic storms & sub-storms etc. To evaluate contribution of various interplanetary parameters that have major role in the geomagnetic storm/geomagnetic variations, the information theory approach is used. In information theory, the measure of uncertainty or randomness of a signal can be quantified by using Shannon entropy or entropy for short. And Transfer entropy is capable of quantifying the directional flow of information between two signals. Thus the Transfer entropy is capable of distinguishing effectively driving and responding signals. In this study, we use Transfer entropy function on Solar wind parameters and ground magnetic data to derive the drivers and relations between them, and also study their contributed effect on ionospheric TEC. In this presentation, we will evaluate and present the results obtained, and discuss about the driving forces on the geomagnetic field disturbances.

  20. 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.

  1. 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.

  2. 77 FR 64935 - Reliability Standards for Geomagnetic Disturbances

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-24

    ...) (2006). \\4\\ Some examples of automatic blocking include series line capacitors, transformer neutral GIC... Grid, at 66 (November 2011) (citing $100,000 cost for neutral-current-blocking- capacitors per... components (e.g., capacitor banks and static VAR compensators) from service. HILF Report at 71....

  3. Large geomagnetic storms of extreme solar event periods in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Wang, Ruiguang

    During extreme solar events such as big flares or/and energetic coronal mass ejections (CMEs) high energy particles are accelerated by the shocks formed in front of fast interplanetary coronal mass ejections (ICMEs). The ICMEs (and their sheaths) also give rise to large geomagnetic storms which have significant effects on the Earth's environment and human life. Around 14 solar cosmic ray ground level enhancement (GLE) events in solar cycle 23 we examined the cosmic ray variation, solar wind speed, ions density, interplanetary magnetic field, and geomagnetic disturbance storm time index ( Dst). We found that all but one of GLEs are always followed by a geomagnetic storm with Dst ⩽ -50 nT within 1-5 days later. Most(10/14) geomagnetic storms have Dst index ⩽ -100 nT therefore generally belong to strong geomagnetic storms. This suggests that GLE event prediction of geomagnetic storms is 93% for moderate storms and 71% for large storms when geomagnetic storms preceded by GLEs. All Dst depressions are associated with cosmic ray decreases which occur nearly simultaneously with geomagnetic storms. We also investigated the interplanetary plasma features. Most geomagnetic storm correspond significant periods of southward Bz and in close to 80% of the cases that the Bz was first northward then turning southward after storm sudden commencement (SSC). Plasma flow speed, ion number density and interplanetary plasma temperature near 1 AU also have a peak at interplanetary shock arrival. Solar cause and energetic particle signatures of large geomagnetic storms and a possible prediction scheme are discussed.

  4. 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

  5. Interplanetary Disturbances Affecting Space Weather

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, Robert F.

    2014-01-01

    The Sun somehow accelerates the solar wind, an incessant stream of plasma originating in coronal holes and some, as yet unidentified, regions. Occasionally, coronal, and possibly sub-photospheric structures, conspire to energize a spectacular eruption from the Sun which we call a coronal mass ejection (CME). These can leave the Sun at very high speeds and travel through the interplanetary medium, resulting in a large-scale disturbance of the ambient background plasma. These interplanetary CMEs (ICMEs) can drive shocks which in turn accelerate particles, but also have a distinct intrinsic magnetic structure which is capable of disturbing the Earth's magnetic field and causing significant geomagnetic effects. They also affect other planets, so they can and do contribute to space weather throughout the heliosphere. This paper presents a historical review of early space weather studies, a modern-day example, and discusses space weather throughout the heliosphere.

  6. 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 (Bzdisturbed geomagnetic 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.

  7. Possible helio-geomagnetic activity influence on cardiological cases

    NASA Astrophysics Data System (ADS)

    Katsavrias, Christos

    Eruptive solar events as flares and coronal mass ejections (CMEs) occur during solar activ-ity periods. Energetic particles, fast solar wind plasma and electromagnetic radiation pass through interplanetary space, arrive on Earth's ionosphere-magnetosphere and produce various disturbances. It is well known the negative influence of geomagnetic substorms on the human technological applications on geospace. During the last 25 years, many studies concerning the possible influence on the human health are published. Increase of the Acute Coronary Syn-dromes and disorders of the Cardiac Rhythm, increase of accidents as well as neurological and psychological disorders (e.g. increase of suicides) during or near to the geomagnetic storms time interval are reported. In this study, we research the problem in Greece, focusing on patients with Acute Myocardial Infraction, hospitalized in the 2nd Cardiological Department of the General Hospital of Nikaea (Piraeus City), for the time interval 1997-2007 (23rd solar cycle) and also to the arrival of emergency cardiological cases to Emergency Department of two greek hospitals, the General Hospital of Lamia City and the General Hospital of Veria City during the selected months, with or without helio-geomagnetic activity, of the 23rd solar cycle. Increase of cases is recorded during the periods with increase helio-geomagnetic activity. The necessity of continuing the research for a longer period and with a bigger sample is high; so as to exact more secure conclusions.

  8. Probing Geomagnetic Jerks combining Geomagnetic and Earth Rotation Observations (Invited)

    NASA Astrophysics Data System (ADS)

    Holme, R. T.; de Viron, O.

    2013-12-01

    Geomagnetic jerks, first observed in the late 1970s, are the most rapid variations in the observed geomagnetic field that are believed to be of internal origin. Their occurence has been correlated with a number of different geophysical phenomena. Here we consider simultaneous features in variations in Earth's length of day. Recently, we have provided a simple description of non-atmospheric variations in length of day (LOD), consisting of 3 components: a slowly varying decadal trend, a 5.9-year oscillation, and occasional sudden jumps. Both of the shorter period parts of this correlate with geomagnetic jerks, with peaks in the LOD oscillation being contemporaneous with well-known jerk occurances (for example in 1969, 1972, 1978 and 1982), and jumps in the LOD fitting a jerk observed in satellite data in 2003.5. The simultaneous observation of these two features constrains Earth structure, in particular limiting the electric conductivity of the deep mantle. However, the nature of the LOD changes also may change the paradigm for the study of jerk timings. it is customarily assumed that the jerks represent features in the geomagnetic field that are continuous in the secular variation, but discontinuous in its derivative, the secular acceleration. However, a jump in LOD suggested by the modelling of the data would correspond also to a jump in SV, thus invalidating standard methods for temporal location of a jerk (which will consider the intersection of best-fit straight lines to the secular variation before and after). Olsen and Mandea have localised a jerk in satellite virtual observatory data using flow modelling; this seems the most promising method to investigate whether jerks could have discontinuous secular variation. We apply similar methods to time series of virtual geomagnetic obseratories from satellite data to further explore geomagnetic jerks and their rotational links in the geomagnetic satellite era.

  9. Large geomagnetic storms of extreme solar event periods in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Wang, R. G.; Wang, J. X.

    At the duration of extreme solar events solar eruption associated with big flares or and energetic coronal mass ejections CMEs can not only make high energy particles acceleration but also give rise to large geomagnetic storms which have significant effects on the Earth s environment and human life Around 14 solar cosmic ray ground level enhancement GLE events in solar cycle 23 we examine the cosmic ray variations solar wind speeds ion densities interplanetary magnetic fields and geomagnetic disturbance storm time indices Dst We find that all but one of GLEs are always followed by a geomagnetic storm with Dst leq -50 nT within 1-5 days later Most 10 14 geomagnetic storms have Dst index leq -100 nT suggesting that GLE event prediction of geomagnetic storms is 93 for moderate storms and 71 for large storms More than half 57 Dst depressions are simultaneously accompanied by cosmic ray decreases and other Dst variabilities are without clear cosmic ray deceases We also investigated the interplanetary plasma features during GLE events Most geomagnetic storm correspond significant periods of southward B z and in close to 80 of the cases that the B z was first northward then turning southward after storm sudden commencement SSC Plasma flow speed ion number density and interplanetary plasma temperature near 1 AU also have a peak at interplanetary shock arrival Solar cause and energetic particle signatures of large geomagnetic storms are discussed

  10. 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.

  11. 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.

  12. 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.

  13. Ground effects of space weather - geomagnetically induced currents

    NASA Astrophysics Data System (ADS)

    Pirjola, Risto

    2002-03-01

    A space storm creates intense rapidly-varying currents in the ionosphere. The most important are auroral electrojet systems. At the Earth's surface, the currents cause a geomagnetic disturbance and an induced electric field. Besides the primary space currents, the surface fields are also affected by secondary currents flowing in the Earth. The electric field drives harmful "geomagnetically induced currents" (GIC) in technological systems with a possibility of large economic losses. The first observations of space weather effects on technological systems were already made in early telegraph equipment 150 years ago. Theoretical modelling of GIC in a technological system firstly requires a "geophysical" calculation of the electric field at the Earth's surface and secondly an "engineering" computation of GIC in the particular earthed network of conductors. In this paper, we summarize the basic principles associated with GIC and consider the research done on the topic in Finland for almost twenty-five years.

  14. 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.

  15. Simulations of the equatorial thermosphere anomaly: Geomagnetic activity modulation

    NASA Astrophysics Data System (ADS)

    Lei, Jiuhou; Wang, Wenbin; Thayer, Jeffrey P.; Luan, Xiaoli; Dou, Xiankang; Burns, Alan G.; Solomon, Stanley C.

    2014-08-01

    The modulation of geomagnetic activity on the equatorial thermosphere anomaly (ETA) in thermospheric temperature under the high solar activity condition is investigated using the Thermosphere Ionosphere Electrodynamics General Circulation Model simulations. The model simulations during the geomagnetically disturbed interval, when the north-south component of the interplanetary magnetic field (Bz) oscillates between southward and northward directions, are analyzed and also compared with those under the quiet time condition. Our results show that ionospheric electron densities increase greatly in the equatorial ionization anomaly (EIA) crest region and decrease around the magnetic equator during the storm time, resulting from the enhanced eastward electric fields. The impact of both the direct heat deposition at high latitudes and the modulation of the storm time enhanced EIA crests on the ETA are subsequently studied. The increased plasma densities over the EIA crest region enhance the field-aligned ion drag that accelerates the poleward meridional winds and consequently their associated adiabatic cooling effect. This process alone produces a deeper temperature trough over the magnetic equator as a result of the enhanced divergence of meridional winds. Moreover, the enhanced plasma-neutral collisional heating at higher latitudes associated with the ionospheric positive storm effect causes a weak increase of the ETA crests. On the other hand, strong changes of the neutral temperature are mainly confined to higher latitudes. Nevertheless, the changes of the ETA purely due to the increased plasma density are overwhelmed by those associated with the storm time heat deposition, which is the major cause of an overall elevated temperature in both the ETA crests and trough during the geomagnetically active period. Associated with the enhanced neutral temperature at high latitudes due to the heat deposition, the ETA crest-trough differences become larger under the minor

  16. Large plasmaspheric electric fields at L approximately 2 measured by the S3-3 satellite during strong geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Gonzalez, W. D.; Pinto, O., Jr.; Mendes, O., Jr.; Mozer, F. S.

    1986-01-01

    Large plasmaspheric electric fields at L is approximately 2 measured by the S3-3 satellite during strong geomagnetic activity are reported. Since these measurements have amplitudes comparable to those of the local corotation electric field, during such events the plasmasphere is expected to get strongly altered event at such low L-values. Furthermore, those measurements could contribute to the understanding of the physics of the convection/electric field penetration to the low latitude plasmaphere as well as the disturbed dynamo, during strong geomagnetic activity. For this purpose, critical parameters related to geomagnetic activity are also presented for the reported electric field events.

  17. Satellite Vulnerability To Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Horne, R. B.; Freemen, M. P.; Riley, D.; Daws, M.; Rutten, K.

    There are several examples where satellites on orbit have failed or partially failed during geomagnetic storms resulting in large insurance claims. Whether the storm is directly responsible for the failures is very controversial, commercially sensitive, and difficult to prove conclusively since there are so few examples. However, there are many non-fatal errors, or anomalies, that occur during the lifetime of spacecraft that enable a statistical analysis. Here we present an analysis of over 5000 satellite anomalies that shows for the first time a statistically significant link between satellite anomalies and geomagnetic storms. We find that the period of highest risk lasts for six days after the start of a magnetic storm. Approximately 40% of anomalies could be due to a random occurrence, but in addition there are between 0 and 35% of satellite anomalies that we attribute as being directly related to geomagnetic storms. We show that the risk depends on satellite prime contractor, orbit type, and age of satellite.

  18. Keith's early work in geomagnetism

    NASA Astrophysics Data System (ADS)

    Lowes, F. J.

    This paper describes how Runcorn was started on his geophysical career by a chance combination of circumstances, when in 1947 he was given the job of measuring the variation of the geomagnetic field with depth inside the Earth, down British coal mines. It then shows how his interest in the semi-conduction of the lower mantle led to attempts to detect DC earth currents, at first again in mines, but later using discarded trans-Pacific telegraph cables. It ends by briefly discussing the “fifth force” measurements he instigated, which, though not a geomagnetic problem, had many similarities with the original mine experiments.

  19. On Geomagnetism and Paleomagnetism

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    1998-01-01

    A statistical description of Earth's broad scale, core-source magnetic field has been developed and tested. The description features an expected, or mean, spatial magnetic power spectrum that is neither "flat" nor "while" at any depth, but is akin to spectra advanced by Stevenson and McLeod. This multipole spectrum describes the magnetic energy range; it is not steep enough for Gubbins' magnetic dissipation range. Natural variations of core multipole powers about their mean values are to be expected over geologic time and are described via trial probability distribution functions that neither require nor prohibit magnetic isotropy. The description is thus applicable to core-source dipole and low degree non-dipole fields despite axial dipole anisotropy. The description is combined with main field models of modem satellite and surface geomagnetic measurements to make testable predictions of: (1) the radius of Earth's core, (2) mean paleomagnetic field intensity, and (3) the mean rates and durations of both dipole power excursions and durable axial dipole reversals. The predicted core radius is 0.7% above the 3480 km seismologic value. The predicted root mean square paleointensity (35.6 mu T) and mean Virtual Axial Dipole Moment (about 6.2 lx 1022 Am(exp 2)) are within the range of various mean paleointensity estimates. The predicted mean rate of dipole power excursions, as defined by an absolute dipole moment <20% of the 1980 value, is 9.04/Myr and 14% less than obtained by analysis of a 4 Myr paleointensity record. The predicted mean rate of durable axial dipole reversals (2.26/Myr) is 2.3% more than established by the polarity time-scale for the past 84 Myr. The predicted mean duration of axial dipole reversals (5533 yr) is indistinguishable from an observational value. The accuracy of these predictions demonstrates the power and utility of the description, which is thought to merit further development and testing. It is suggested that strong stable stratification

  20. Comparisons of geomagnetic transmission measurements with modified Tsyganenko 1989 model calculations for the October 1989 Solar Energetic Particle events

    NASA Astrophysics Data System (ADS)

    Boberg, P. R.; Smart, D. F.; Shea, M. A.; Tylka, A. J.

    2016-01-01

    We have determined eight-second averaged geomagnetic transmissions of 36-80 MeV protons for the large Solar Energetic Particle (SEP) events and geomagnetic activity level variations of October 1989 using measurements from the NOAA-10 and GOES-7 satellites. We have compared the geomagnetic transmission measurements with model calculations employing trajectory tracings through the combined International Geomagnetic Reference Field (IGRF) and Kp/Dst modified 1989 Tsyganenko model. We present threshold geomagnetic transmission geographic latitudes and magnetic latitudes, as well as (a) differences between the measured and calculated threshold geographic latitudes and magnetic latitudes and (b) differences between measured and calculated polar pass durations. We find that for less disturbed geomagnetic activity levels, the measured threshold geomagnetic transmission geographic and magnetic latitudes are typically about 1-1.5° equatorward of the calculated geographic and magnetic latitudes, while for larger geomagnetic activity levels, the measured geographic and magnetic latitudes can be about 1.5° poleward of the calculated geographic and magnetic latitudes. For the eight Kp bins, we also compare the mean measured magnetic latitudes as a function of mean Dst with the mean calculated magnetic latitudes, interpolated to the mean measured Dst values. These comparisons of mean magnetic latitudes illustrate the improvement in the accuracy of the model calculations resulting from employing the actual mean measured Dst values.

  1. Day-to-Day Variability of H Component of Geomagnetic Field in Central African Sector Provided by YACM (Yaoundé-Cameroon) Amber Magnetometer Station

    NASA Astrophysics Data System (ADS)

    Etoundi Messanga, Honoré

    2015-04-01

    The geomagnetic data obtained from Amber Network station in Cameroon has been used for this study. The variability of H component of geomagnetic field has been examined by using geomagnetic field data of X and Y components recorded at AMBER magnetometer station hosted by the Department of Physics of University of Yaoundé (3.87°N, 11.52°E). The day-to-day variability of the horizontal intensity of the geomagnetic field has been examined and shows that the scattering of H component of magnetic field variation is more on disturbed than on quiet days. The signatures H of geomagnetic Sq and Sd variations in intensities in the geomagnetic element, has been studied. This paper shows that the daytime variations in intensities of geomagnetic elements H, Sq(H) and Sd(H) respectively are generally greater at diurnal-times than at night-times. This study mainly interests to answer to two questions: 1) how can geomagnetic variations be used to study the equatorial ionosphere electrodynamics and electrojet equatorial over Africa in general and Cameroon in particular? 2) How can geomagnetic variations be used to monitor and predict Space weather events in Cameroon? This study presents and interprets the results of H component of geomagnetic field variations during magnetic storms and on quiet days.

  2. 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.

  3. Advantage of wavelet technique to highlight the observed geomagnetic perturbations linked to the Chilean tsunami (2010)

    NASA Astrophysics Data System (ADS)

    Klausner, V.; Mendes, Odim; Domingues, Margarete O.; Papa, Andres R. R.; Tyler, Robert H.; Frick, Peter; Kherani, Esfhan A.

    2014-04-01

    The vertical component (Z) of the geomagnetic field observed by ground-based observatories of the International Real-Time Magnetic Observatory Network has been used to analyze the induced magnetic fields produced by the movement of a tsunami, electrically conducting sea water through the geomagnetic field. We focus on the survey of minutely sampled geomagnetic variations induced by the tsunami of 27 February 2010 at Easter Island (IPM) and Papeete (PPT) observatories. In order to detect the tsunami disturbances in the geomagnetic data, we used wavelet techniques. We have observed an 85% correlation between the Z component variation and the tide gauge measurements in period range of 10 to 30 min which may be due to two physical mechanisms: gravity waves and the electric currents in the sea. As an auxiliary tool to verify the disturbed magnetic fields, we used the maximum variance analysis (MVA). At PPT, the analyses show local magnetic variations associated with the tsunami arriving in advance of sea surface fluctuations by about 2 h. The first interpretation of the results suggests that wavelet techniques and MVA can be effectively used to characterize the tsunami contributions to the geomagnetic field and further used to calibrate tsunami models and implemented to real-time analysis for forecast tsunami scenarios.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Global structure of ionospheric TEC anomalies driven by geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Pancheva, D.; Mukhtarov, P.; Andonov, B.

    2016-07-01

    This study examines the structure and variability of the ionospheric TEC anomalies driven by geomagnetic storms. For this purpose the CODE global ionospheric TEC data from four geomagnetically disturbed periods (29 October-1 November 2003, 7-10 November 2004, 14-15 December 2006, and 5-6 August 2011) have been considered. By applying the tidal analysis to the geomagnetically forced TEC anomalies we made an attempt to identify the tidal or stationary planetary wave (SPW) signatures that may contribute to the generation of these anomalies. It has been found that three types of positive anomalies with different origin and different latitudinal appearance are observed. These are: (i) anomalies located near latitudes of ±40° and related to the enhancement and poleward moving of the equatorial ionization anomaly (EIA) crests; (ii) anomalies located near latitudes of ±60° and seen predominantly in the night-side ionosphere, and (iii) very high latitude anomalies having mainly zonally symmetric structure and related to the auroral heating and thermospheric expansion. The decomposition analysis revealed that these anomalies can be reconstructed as a result of superposition of the following components: zonal mean (ZM), diurnal migrating (DW1), zonally symmetric diurnal (D0), and stationary planetary wave 1 (SPW1).

  9. Geomagnetic activity effects on the equatorial neutral thermosphere

    SciTech Connect

    Burrage, M.D.; Abreu, V.J.; Orsini, N. ); Fesen, C.G. ); Roble, R.G. )

    1992-04-01

    The effects of geomagnetic activity on the equatorial neutral thermosphere are investigated with mass spectrometer measurements from the Atmosphere Explorer E (AE-E) satellite and simulations generated by the National Center for Atmospheric Research thermosphere/ionosphere general circulation model (TIGCM). A study of the local time dependence of the equatorial geomagnetic storm response concentrates on a disturbed period from March 20 (day 79) to March 31 (day 90), 1979. This interval was the subject of an intense data-gathering and analysis campaign for the Coordinated Data Analysis Workshop 6, and global TIGCM predictions are available for the specific conditions of the storm as a function of universal time. The AE-E measurements demonstrate that significant geomagnetic storm-induced perturbations of upper thermospheric N{sub 2} and O densities extend into the equatorial zone but are mainly restricted to the midnight/early morning sector. The qualitative features of the observations are reproduced by the TIGCM, although in general, the model simulations overestimate the storm temperature and density enhancements, primarily in the nighttime thermosphere. This suggests that either the nighttime cooling rates in the TIGCM are too small or that the specified auroral forcing of the model are too persistent.

  10. Geomagnetic Effect Caused by 1908 Tunguska Event

    NASA Astrophysics Data System (ADS)

    Losseva, T. V.; Kuzmicheva, M. Y.

    2010-12-01

    results of this current system shows that an unique azimuth of trajectory of the body exists, for which the variations of all three components of the geomagnetic field do not contradict to the observation data. This azimuth is equal to 306 degrees, while other estimates are in the range of 290-344 degrees. This idea of the atmospheric plume ejected along the trajectory and ionization in the upper atmosphere, caused by the following atmospheric oscillations, could explain the geomagnetic effect both in general and locally in Irkutsk observatory: the time delay and the variations of all magnetic field components. Binding of simulation results of observation data also allows us to select the unique trajectory azimuth for Tunguska body. References: [1] Ivanov K.G. The Geomagnetic phenomena, which were being observed on the Irkutsk magnetic observatory, following the explosion of the Tunguska meteorite //Meteoritika. 1961. Iss. XXI. P.46-49 (in Russian). [2] Losseva T., Merkin V., Nemtchinov I. Estimations of the Aeronomical and Electromagnetic Disturbances in the E-layer of the Ionosphere, caused by Tunguska Event // AGU Fall Meeting. 1999. SA32A-09.

  11. A new regard about Surlari National Geomagnetic Observatory

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    stations set on satellites circling on orbits around the Earth. In Romania, fundamental research in this field have developed within a special unit SNGO, which has followed ever since its foundation two main objectives: a permanent observation of planetary magnetic field within a world net of observatories, and rendering evident some local disturbances connected, through electromagnetic induction, to the geological structure of our country's territory. Since 1998, Romanian researchers have been allowed to take part in the largest international scientific cooperation programme in the field INTERMAGNET. Last year in SNGO was made modernize of infrastructure, techniques, apparatus and informatics system suitable for acquisition, procession and interpretation of data for a continuous and systematic study of Earth electromagnetic field. After geomagnetic field and telluric field analysis of external components (daily, semi-daily, continuous and non-continuous pulsations, disturbances magnetic storms, seismic-electric signals, etc), as well as of internal components correlated with geodynamic activity and events with natural risk. Correlative phenomenological interpretation of the results obtained by SNGO with the ones obtained by other geomagnetic observatories in the INTERMAGNET network, as well as to the possibility of separating causes at local, regional and planetary scale.

  12. 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].

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Finnish geomagnetically induced currents project

    SciTech Connect

    Vilianen, A.; Pirjola, R. . Dept. of Geophysics)

    1995-01-01

    This article is a summary of Results of the Finnish Project on Geomagnetically Induced Currents,'' published in Surveys in Geophysics 15:383-408, Kluwer Academic Publishers, Netherlands, 1994. IVO and FMI carried out a 1-year GIC project from June 1991 to May 1992. The time of the project was a little after the sunspot maximum, and the geomagnetic activity was high; there were 34 major or severe magnetic storm days (A[sub k] index at least 50). The main aim was to derive reliable statistics of the occurrences of GICs at different sites of the Finnish 400 and 220 kV power systems. Besides the practical engineering purpose, the project is also geophysically relevant by providing a GIC data set usable for large-scale investigations of auroral ionospheric-magnetospheric processes and of the earth's structure.

  20. 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

  1. Forecasts of geomagnetic secular variation

    NASA Astrophysics Data System (ADS)

    Wardinski, Ingo

    2014-05-01

    We attempt to forecast the geomagnetic secular variation based on stochastic models, non-parametric regression and singular spectrum analysis of the observed past field changes. Although this modelling approach is meant to be phenomenological, it may provide some insight into the mechanisms underlying typical time scales of geomagnetic field changes. We follow two strategies to forecast secular variation: Firstly, by applying time series models, and secondly, by using time-dependent kinematic models of the advected secular variation. These forecasts can span decades, to longer periods. This depends on the length of the past observations used as input, with different input models leading to different details in the forecasts. These forecasts become more uncertain over longer forecasting periods. One appealing reason is the disregard of magnetic diffusion in the kinematic modelling. But also the interactions of unobservable small scale core field with core flow at all scale unsettle the kinematic forecasting scheme. A further (obvious) reason is that geomagnetic secular variation can not be mimicked by linear time series models as the dynamo action itself is highly non-linear. Whether the dynamo action can be represented by a simple low-dimensional system requires further analysis.

  2. Future of geomagnetism and paleomagnetism

    NASA Astrophysics Data System (ADS)

    Banerjee, S. K.; Cain, J. C.; Van der Voo, R.

    After the heady days of the 1960s, when geomagnetism and paleomagnetism provided crucial quantitative evidence for plate tectonics by establishing the geomagnetic polarity timescale, the 1980s may appear to be somewhat tame in the eyes of an average geophysicist. To such a person, the intervening 1970s may well look like a period of “mopping up” after the big event has happened, and it may not be unfair for him or her to ask what significant discoveries in geomagnetism and paleomagnetism (GP) have been made since 1970. The practitioners in this field of research are individuals who carry out their work without a large degree of formal overlap, so it is not surprising that the same question about recent accomplishments has arisen also in the minds of AGU GP Section members. This question came to the forefront especially during the 1984 AGU Fall Meeting, when members spoke strongly (in private conversations) about a perceived decrease in National Science Foundation funding of GP-related research projects.

  3. 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.

  4. Auroral LSTIDs and SAR Arc Occurrences in Northern California During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Bhatt, A.; Kendall, E. A.

    2015-12-01

    A 630nm allsky imager has been operated for two years in northern California at the Hat Creek Radio Observatory. F-region airglow data captured by the imager ranges from approximately L=1.7 -2.7. Since installation of the imager several geomagnetic storms have occurred with varying intensities. Two main manifestations of the geomagnetic storms are observed in the 630 nm airglow data: large-scale traveling ionospheric disturbances that are launched from the auroral zone and Stable Auroral Red (SAR) arcs during more intense geomagnetic storms. We will present a statistical analysis of these storm-time phenomena in northern California for the past eighteen months. This imager is part of a larger all-sky imaging network across the continental United States, termed MANGO (Midlatitude All-sky-imaging Network for Geophysical Observations). Where available, we will add data from networked imagers located at similar L-shell in other states as well.

  5. Automated classification of solar wind disturbances

    NASA Astrophysics Data System (ADS)

    Vennerstrom, Susanne; Leer, Kristoffer

    2015-04-01

    Geomagnetic storms are known to be caused by solar wind disturbances associated with the passage of either interplanetary coronal mass ejections (ICMEs) or stream interaction regions (SIRs) associated with high-speed streams from coronal holes. We present and assess a new method for automated detection and subsequent classification of solar wind disturbances arriving at L1. The method requires solar wind in situ plasma and magnetic field observations, currently provided in near real-time by NOAA/NASA from the ACE SWEPAM and MAG instruments. Periods of significantly enhanced magnetic field are identified and classified according to their most likely cause, being either ICMEs or high speed streams creating stream interaction regions SIRs. In the output the disturbed intervals are thus classified either as "ICME"-related, "SIR"-related or "NO ID". We compare the results statistically with existing lists of ICMEs and SIRs derived manually, and assess the usefulness of the service for providing early warnings of upcoming geomagnetic storms.

  6. Restoration project of geomagnetic survey in Latvia

    NASA Astrophysics Data System (ADS)

    Burlakovs, J.; Lembere, I.

    2003-04-01

    THE RESTORATION PROJECT OF GEOMAGNETIC SURVEY IN LATVIA J. Burlakovs, I. Lembere State Land Service of Latvia, Geodesy Board juris.burlakovs@gp.vzd.gov.lv / Fax: +371-7612736 The aim of geomagnetic survey measurements is to study the geomagnetic field at global, regional as well as local scales. To determine secular changes of the geomagnetic field it is very important to do a lot of regular field work. Recalculation and comparison of measured data for corrections must be made using the observatory or magnetic station data collected nearby the investigated area in the real-time. Field geomagnetic survey measurements in Latvia have not been made since 1991. The State Land Service of Latvia, the Geodesy Board plans to restart such kind of measurements in Latvia. The repeat station network must be renewed, regular magnetic declination, inclination and total field intensity data must be gathered, compared with the observatory data and secular changes of the geomagnetic field discovered. It is also possible to do regional correlations for data to determine future trends of the geomagnetic field changes. The detection of geomagnetic anomalies and the reason of the existence of those at particular territories could be made. Such kind of measurements demands the highest accuracy and therefore is necessary to cooperate with geomagnetic research network groups in neighbouring areas - Estonia, Finland and Poland, where permanent magnetic stations are situated. One permanent magnetic station also could be established in Latvia to do permanent recordings of geomagnetic field components, which give the possibility to do regional corrections for separate measurement recordings in the field. Geomagnetic field studies are important for cartography, navigational and military needs, also it is possible to use this information together with geological and geophysical data to create and specify the geological model for the territory. In future Latvia must participate within the

  7. 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.

  8. Geomagnetic field changes in association with the 2011 Tohoku-Oki Earthquake and Tsunami

    NASA Astrophysics Data System (ADS)

    Utada, H.; Shimizu, H.; Ogawa, T.; Maeda, T.; Furumura, T.; Yamamoto, T.; Yamazaki, N.; Yoshitake, Y.; Nagamachi, S.

    2011-12-01

    Does the geomagnetic field change in association with or prior to Earthquakes? This question was first raised more than 100 years ago, and since that time, theoretical and observational research has been conducted in order to obtain an answer to this question. Large earthquakes provide an opportunity to examine this problem, because large signals are generally expected in association with large earthquakes. We herein present a preliminary report of simultaneous measurements of the geomagnetic field in association with the 2011 Tohoku Earthquake (M9.0) and Tsunami by magnetometers operating in Japan. Geomagnetic data sampled at every minute from 14 geomagnetic stations were collected, and the total intensity (from all stations) and three components (from stations available) from January 1 to March 22, 2011 were analyzed. Since the earthquake occurred during a geomagnetic storm, we used time series after correcting the effect of external disturbance and its induced fields by taking two horizontal components of KNY as a reference. A coseismic change of the geomagnetic total intensity was observed at several stations located relatively close to the epicenter. We did not estimate coseismic changes in the three component data, because of the presence of apparent offsets caused by strong quakes. The magnitude of this coseismic change in the total intensity was on the order of 1 nT or less, which is consistent with predictions based on piezomagnetic theory. More distinct and rapid changes were observed which started immediately after the main shock and continued for a few hours. Although the rapid change was observed in every component, the amplitude of declination change is the largest which started about 10 minutes after the main shock. Before this declination change, changes of a few nT in the vertical component and the total intensity were observed at stations close to the epicenter. The former change is supposed to be caused by the ionospheric disturbance, and the

  9. 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).

  10. 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.

  11. Sparkling Geomagnetic Field: Involving Schools in Geomagnetic Research

    NASA Astrophysics Data System (ADS)

    Bailey, Rachel; Leonhardt, Roman; Leichter, Barbara

    2014-05-01

    Solar activity will be reaching a maximum in 2013/2014 as the sun reaches the end of its cycle, bringing with it an opportunity to study in greater detail the effect of solar wind or "space weather" on our planet's magnetic field. Heightened solar activity leads to a larger amount of clouds of energetic particles bombarding the Earth. Although the Earth's magnetic field shields us from most of these particles, the field becomes distorted and compacted by the solar wind, which leads to magnetic storms that we detect from the surface. These storms cause aurorae at higher latitudes and can lead to widespread disruption of communication and navigation equipment all over the Earth when sufficiently strong. This project, "Sparkling Geomagnetic Field," is a part of Austria's Sparkling Science programme, which aims to involve schools in active scientific research to encourage interest in science from a young age. Researchers from the Central Institute for Meteorology and Geodynamics (ZAMG) in Vienna have worked hand-in-hand with three schools across Austria to set up regional geomagnetic stations consisting of state-of-the-art scalar and vector magnetometers to monitor the effects of the solar wind on the geomagnetic field. The students have been an active part of the research team from the beginning, first searching for a suitable location to set up the stations as well as later overseeing the continued running of the equipment and analysing the data output. Through this project the students will gain experience in contemporary scientific methods: data processing and analysis, field work, as well as equipment setup and upkeep. A total of three stations have been established with schools in Innsbruck, Tamsweg and Graz at roughly equal distances across Austria to run alongside the already active station in the Conrad Observatory near Vienna. Data acquisition runs through a data logger and software developed to deliver data in near realtime. This network allows for

  12. Total electron content variations observed at a low latitude GPS station in association to geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Mendes da Costa, A.; Fonseca Junior, E.; Vilas Boas, J.

    Total electron content (TEC) has been continuously monitored since January 1997, using a GPS dual frequency receiver located at Presidente Prudente (22o 07'S, 51o 22' W). In this paper the enhancements observed in the ionspheric TEC are associated with geomagnetic field variations for six geomagnetic storms that occurred from 1997 to 2000. The events were selected according to the integrity and availability of data. The purpose of this study is to provide a better knowledge of the low-latitude behavior of TEC in association to geomagnetic storms. Quiet-time TEC values were obtained by the average of the five magnetically less disturbed days of the month. These values were subtracted from the TEC hourly averages measured during the period of the magnetic storms. Magnetic field intensity measured on the ground was used for the identification of the storm time variations and the Dst indices were also included as a reference for the latitudes considered. The results showed that moderate geomagnetic storms produce small effects in TEC, intense and super intense (Dst < ~150 nT) geomagnetic storms produce well defined and long lasting TEC enhancements. The super intense storms cause the GPS signals to loose their track and the corresponding TEC values cannot be derived.

  13. 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.

  14. Statistical maps of geomagnetic perturbations as a function of the interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Weimer, D. R.; Clauer, C. R.; Engebretson, M. J.; Hansen, T. L.; Gleisner, H.; Mann, I.; Yumoto, K.

    2010-10-01

    Mappings of geomagnetic perturbations are shown for different combinations of the solar wind velocity, interplanetary magnetic field (IMF), and dipole tilt angle (season). Average maps were derived separately for the northward, eastward, and vertical (downward) components of the geomagnetic disturbances, using spherical cap harmonics in least error fits of sorted measurements. The source data are obtained from 104 ground-based magnetometer stations in the Northern Hemisphere at geomagnetic latitudes over 40° during the years 1998 through 2001. Contour maps of statistical fits are shown along-side scatter plots of individual measurements in corrected geomagnetic apex coordinates. The patterns are consistent with previous mappings of ionospheric electric potential. Interestingly, the vertical component of the magnetic perturbations closely resembles maps of the overhead, field-aligned currents, including the Northward IMF configuration. The maximum and minimum values from the statistical mappings are graphed to show their changes as a function of southward IMF magnitude, solar wind velocity, and seasons. It is expected that this work will lead to better advance predictions of the geomagnetic perturbations that are based on real-time IMF measurements.

  15. Multiscale and cross entropy analysis of auroral and polar cap indices during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Gopinath, Sumesh; Prince, P. R.

    2016-01-01

    In order to improve general monoscale information entropy methods like permutation and sample entropy in characterizing the irregularity of complex magnetospheric system, it is necessary to extend these entropy metrics to a multiscale paradigm. We propose novel multiscale and cross entropy method for the analysis of magnetospheric proxies such as auroral and polar cap indices during geomagnetic disturbance times. Such modified entropy metrics are certainly advantageous in classifying subsystems such as individual contributions of auroral electrojets and field aligned currents to high latitude magnetic perturbations during magnetic storm and polar substorm periods. We show that the multiscale entropy/cross entropy of geomagnetic indices vary with scale factor. These variations can be attributed to changes in multiscale dynamical complexity of non-equilibrium states present in the magnetospheric system. These types of features arise due to imbalance in injection and dissipation rates of energy with variations in magnetospheric response to solar wind. We also show that the multiscale entropy values of time series decrease during geomagnetic storm times which reveals an increase in temporal correlations as the system gradually shifts to a more orderly state. Such variations in entropy values can be interpreted as the signature of dynamical phase transitions which arise at the periods of geomagnetic storms and substorms that confirms several previously found results regarding emergence of cooperative dynamics, self-organization and non-Markovian nature of magnetosphere during disturbed periods.

  16. 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.

  17. Causal relationships between solar and geomagnetic cycles

    NASA Astrophysics Data System (ADS)

    Ponyavin, D. I.

    2006-12-01

    Sunspots are sui generis "hot spots" that display the most responsive regions to solar cycle changes. Rudolf Wolf in 1848 derived a simple measure of solar cyclicity by counting a number of sunspots and sunspot groups at the solar disk. Edward Sabine in 1852 announced that geomagnetic cycle was "absolutely identical" to solar cycle. However geomagnetic and sunspot indices due to their different nature do not exhibit similar variations and often manifest out of phase behavior. Long-term sunspot and geomagnetic time-series were studied using wavelet transforms and recurrence plot techniques. We have analyzed similarities and relationships between sunspot and geomagnetic cycles in order to find recurrence, synchronization and phase differences on interannual scale. Predictive schemes of the current and future solar cycles using geomagnetic proxies were analyzed and discussed.

  18. 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.

  19. 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.

  20. [Effect of geomagnetic activity on the functional status of the body].

    PubMed

    Oraevskiĭ, V N; Breus, T K; Baevskiĭ, R M; Rapoport, S I; Petrov, V M; Barsukova, Zh V; Gurfinkel', Iu I; Rogoza, A T

    1998-01-01

    A complicated nonlinear biological system should be in principal more sensitive to the external factors activity including geomagnetic disturbances. The complex of experimental studies based on this hypothesis were done simultaneously in two hospitals in Moscow as well as in condition of space orbital station, where just above-mentioned conditions are the case. This studies revealed that the reaction of astronauts to the geomagnetic storm involves a mobilization and activation of all centers of the sympathetic link, and as a result,--a significant increase and stabilization of pulse (heart rate), decrease of the heart rhythm variability and the power of respiratory waves. This nonspecific adaptation stress-reaction was accompanied by variations in the regulation of vascular tonus which is correspond to specific adaptation stress-reaction. The results of clinical examinations of healthy people and patients with the ischemic heart disease lead us to the conclusion that the reaction to the geomagnetic disturbances are mainly of one type and manifests themselves in deterioration of the physiological status, rheologic blood characteristics and the heart rate disturbances similar to ones observed in astronautes. PMID:9914843

  1. 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

    on solar activity: protons and electrons increase in the solar wind; increase of the electromagnetic emissions on Earth's magnetic poles; reducing of the magnetopause standoff distance; intense and sudden changes in the interplanetary magnetic field (IMF). The beginning of the geomagnetic disturbance that precedes the earthquake is activated by an protons and electrons density increase in the solar wind that can be monitored through telemetric data sent by satellite ACE (Advanced Composition Explorer) that currently operating in a Lissajous orbit near the Lagrange point "L1" (between the Sun and Earth, at a distance of approximately 1.5 million km from Earth).

  2. 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.

  3. [Climacteric disturbances. 2. Therapy of climacteric disturbances].

    PubMed

    Döring, G K

    1976-07-01

    After defining the terms climacterium and menopause the causes of climacteric disturbances are explained. During the premenopausal stage disturbances of the cycle are prevailing, caused by an insufficiency of the corpus luteum. Of climacteric disturbances should be spoken only after menopause. They are divided into: vegetative disturbances, troubles of metabolism, cardiovascular dysregulation, psychic deviations, sexual troubles and changes of the skin. The therapy of disturbances during the premenopausal stage mainly consists of the substitution of progesterone or in a cycle-like estrogen-progesterone-therapy. In the premenopausal stage estrogens are the therapy of choice. Among orally efficient estrogens the conjugated estrogen and the estradiol-valerianat are preferred. Side-effects and contraindications are discussed in detail. Among gynecologists there exists no disagreement about the necessity of therapy of serious climacteric disturbances, the opinions about prophylactic estrogen-therapy in women differ. PMID:184019

  4. On the Responses of Geomagnetic Field at African and Asian Longitudes during the Storm of April 2010

    NASA Astrophysics Data System (ADS)

    Falayi, E.; Rabiu, A.; Yumoto, K.; Uozumi, T.; Magdas, M.

    2010-12-01

    The geomagnetic horizontal (H) field from the chain of 16 MAGDAS magnetic observatories along African and Asian longitudes are used to study the storm-time and disturbance daily variations. Geomagnetic field components vary when the interplanetary magnetic field is oriented in southward direction. Also effect of sudden magnetospheric compression is clearly seen at all latitudes. There is persistent decrease of H of disturbance daily variation during the storm at equatorial latitudes which could be the effect of a westward electric field due to the Disturbance Ionospheric dynamo coupled with abnormally large electrical conductivities in the E region over the equator. Therefore by analysing the data observed in the stations along African and Asian longitudes during the magnetic storm, the variations in electromagnetic environment in the near-earth space could be obtained.

  5. 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.

  6. Comparison of Dst Forecast Models for Intense Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Ji, Eun-Young; Moon, Y.-J.; Gopalswamy, N.; Lee, D.-H.

    2012-01-01

    We have compared six disturbance storm time (Dst) forecast models using 63 intense geomagnetic storms (Dst <=100 nT) that occurred from 1998 to 2006. For comparison, we estimated linear correlation coefficients and RMS errors between the observed Dst data and the predicted Dst during the geomagnetic storm period as well as the difference of the value of minimum Dst (Delta Dst(sub min)) and the difference in the absolute value of Dst minimum time (Delta t(sub Dst)) between the observed and the predicted. As a result, we found that the model by Temerin and Li gives the best prediction for all parameters when all 63 events are considered. The model gives the average values: the linear correlation coefficient of 0.94, the RMS error of 14.8 nT, the Delta Dst(sub min) of 7.7 nT, and the absolute value of Delta t(sub Dst) of 1.5 hour. For further comparison, we classified the storm events into two groups according to the magnitude of Dst. We found that the model of Temerin and Lee is better than the other models for the events having 100 <= Dst < 200 nT, and three recent models (the model of Wang et al., the model of Temerin and Li, and the model of Boynton et al.) are better than the other three models for the events having Dst <= 200 nT.

  7. 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.

  8. 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.

  9. 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.

  10. Solar wind and geomagnetism: toward a standard classification of geomagnetic activity from 1868 to 2009

    NASA Astrophysics Data System (ADS)

    Zerbo, J. L.; Amory Mazaudier, C.; Ouattara, F.; Richardson, J. D.

    2012-02-01

    We examined solar activity with a large series of geomagnetic data from 1868 to 2009. We have revisited the geomagnetic activity classification scheme of Legrand and Simon (1989) and improve their scheme by lowering the minimum Aa index value for shock and recurrent activity from 40 to 20 nT. This improved scheme allows us to clearly classify about 80% of the geomagnetic activity in this time period instead of only 60% for the previous Legrand and Simon classification.

  11. VLF emissions and whistlers observed during geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Ondoh, T.; Tanaka, Y.; Nishizaki, R.; Nagayama, M.

    1974-01-01

    Whistler-triggered emissions and a narrowband hiss are described which were observed over Japan by ISIS 2 during the main phase of the geomagnetic storm of August 9, 1972. The characteristics of the narrowband hiss and increases in the whistler rate during the storm are discussed, and the ISIS-2 data are compared with data on whistler cutoffs and VLF noise breakups obtained by OGO 4 and Alouette I. Since the whistlers and narrowband hiss are usually observed inside and outside the plasmapause, it is thought that the plasmapause may have been located near the low-latitude end of the narrowband hiss during the main phase of the storm. It is suggested that the increases in the whistler rate may have been caused by the formation of whistler ducts in the disturbed plasmapause.

  12. Some data about the relationship between ths human state and external perturbations of geomagnetic field

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.; Stoilova, I.; Yanev, T.

    The influence of solar activity changes and related to them geomagnetic field variations on human health is confirmed in a lot of publications but the investigations in this area are still sporadic and incomplete because of the fact that it is difficult to separate the geomagnetic influence from the environmental factor complex, which influence the human life activity. That is why we have studied the influence of changes in geomagnetic activity on human physiological, psycho-physiological parameters and behavioural reactions. In this article we looked for influence of changes in GMA on the systolic and diastolic blood pressure and pulse-rate. We examined 54 volunteers. 26 persons of them had some cardio-vascular or blood pressure disturbances. The registrations were performed every day at one and the same time for each person during the period 1.10 - 10.11.2001. Four-way analysis of variance (MANOVA method) with factors: GMA, day, sex and cardiovascular pathology was performed. GMA was divided into four levels according to the Kp- and Ap-index values. The days examined were divided into six levels in relation to the day with increased GMA. Factor "cardiovascular pathology" was divided into two levels: healthy subjects and subjects that had some cardio -vascular or blood pressure disturbances. When we employed four-way analysis of variance, the influence of some of the factors on the physiological parameters examined turned out to be statistically significant at p<0.05. Our investigations indicate that most of the persons examined irrespectively to their status could be sensitive to the geomagnetic disturbances.

  13. 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

  14. 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.

  15. 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.

  16. 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/

  17. 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

  18. Characterizing quasi-periodic disturbances in GPS TEC data and their drivers

    NASA Astrophysics Data System (ADS)

    Wurtz, J.; Coster, A. J.; Goncharenko, L.; Zhang, S.

    2012-12-01

    We examine a large data set (2003-2009) of total electron content (TEC) values derived from a global network of differential GPS receivers that was downloaded from the Madrigal database. We report on TEC oscillations at multiple periods ranging from 5 to ~30 days. A significant portion of oscillations with 9-day and 13.5-day periods is driven by the recurrent geomagnetic activity, as evident from the analysis of geomagnetic indices. The TEC disturbances in response to the recurrent geomagnetic activity are stronger at middle and high latitudes, and are less pronounced at lower latitudes (< 30 degrees). We also observe a correlation between TEC and the 28-day lunar cycle that is more evident at lower (equatorial) latitudes in both northern and southern hemispheres. The TEC disturbances associated with the lunar cycle are well pronounced during the northern hemisphere winter and equinox seasons.

  19. Comparative climatological study of large-scale traveling ionospheric disturbances over North America and China in 2011-2012

    NASA Astrophysics Data System (ADS)

    Ding, Feng; Wan, Weixing; Li, Qiang; Zhang, Rui; Song, Qian; Ning, Baiqi; Liu, Libo; Zhao, Biqiang; Xiong, Bo

    2014-01-01

    This paper describes a comparative study of the climatology of large-scale traveling ionospheric disturbances (LSTIDs) over North America and China based on observations obtained in 2011-2012 using two GPS networks characterized by dense regional coverage. We identified a total of 390 LSTIDs in China and 363 events in North America. These can be categorized into three types, namely south, north, and westward propagating LSTIDs. The southward LSTIDs over North America show similar diurnal and seasonal variations to those of geomagnetic disturbances, but the southward LSTIDs over China do not show such variations. The occurrence of southward LSTIDs over China increases at ~1-2 h after the time of geomagnetic activity maximum; this increase lasts several hours until the geomagnetic minimum, which happens during the local evening. The southward LSTIDs over North America show a semiannual variation with two peaks in March and October, while the southward LSTIDs over China show a major peak in January. Northward LSTIDs occur much less frequently than their southward counterparts, and they are mainly observed in China. They mostly occur during geomagnetic activity maximum, indicating a possible relation with the degree of geomagnetic activity. Westward LSTIDs are seen in both regions during local sunrise and may be excited by the moving solar terminator. No relationship was found between these latter LSTIDs and the geomagnetic disturbances. The propagation direction of westward events changed from northwestward during winter solstice to southwestward at summer solstice. This is consistent with the seasonal orientation of the solar terminator.

  20. Ergodicity of the recent geomagnetic field

    NASA Astrophysics Data System (ADS)

    De Santis, A.; Qamili, E.; Cianchini, G.

    2011-06-01

    The geomagnetic field is a fundamental property of our planet: its study would allow us to understand those processes of Earth's interior, which act in its outer core and produce the main field. Knowledge of whether the field is ergodic, i.e. whether time averages correspond to phase space averages, is an important question since, if this were true, it would point out a strong spatio-temporal coupling amongst the components of the dynamical system behind the present geomagnetic field generation. Another consequence would be that many computations, usually undertaken with many difficulties in the phase space, can be made in the conventional time domain. We analyse the temporal behaviour of the deviation between predictive and definitive geomagnetic global models for successive intervals from 1965 to 2010, finding a similar exponential growth with time. Also going back in time (at around 1600 and 1900 by using the GUFM1 model) confirms the same findings. This result corroborates previous chaotic analyses made in a reconstructed phase space from geomagnetic observatory time series, confirming the chaotic character of the recent geomagnetic field with no reliable prediction after around 6 years from definitive values, and disclosing the potentiality of estimating important entropic quantities of the field by time averages. Although more tests will be necessary, some of our analyses confirm the efforts to improve the representation of the geomagnetic field with more detailed secular variation and acceleration.

  1. Possible Geomagnetic and Environmental Symptoms in the Area of Athens During the Solar Cycle No 22

    NASA Astrophysics Data System (ADS)

    Nastos, P. T.; Paliatsos, A. G.; Korbakis, G. K.; Tritakis, V. P.; Bergiannaki, A.; Psarros, K.; Paparrigopoulos, P.; Stafanis, K.

    The goal of this research is to confirm possible influences of environmental and geomagnetic variability in psychiatric hygiene of sensitive and heavily psychological patients. Three yearly samples of psychological patients consisted by four thousand cases (4000) each have been studied. The patients have been filed by the psychiatric clinic of the Eginition hospital in Athens where the three samples have been compiled during three very characteristic years of the No 22 11-year cycle, the maximum (1989), the minimum (1996) and one intermediate year of the descending branch (1994). A file with five to eight psychological symptoms like depression, sleep disturbance anxiety, aggressiveness etc. is attached to every patient. Each of these symptoms is correlated to the local geomagnetic index (k-index), the international geomagnetic index (Dst) and the environmental index (DI, Discomfort Index) in both daily and monthly basis. A clear seasonal variation in almost all symptoms and samples is present with maximum at the end of summer (August/September) and minimum at the end of winter (February-March). In addition very significant correlations among DI, Dst and some psychological symptoms appear. The main conclusion is that meteorological and geomagnetic factors play a significant role in the formation of sensitive psychological patients, behavior

  2. 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.

  3. 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.

  4. Probabilistic Forecasting Analysis of Geomagnetic Indices for IMF Bs-events

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Moldwin, M.

    2014-12-01

    Strong southward interplanetary magnetic field (IMF Bs) intervals are important to drive disturbances in the Earth's magnetosphere. However, high-accuracy forecast of IMF Bz is not available from current heliospheric models. Here we perform a follow-up study of McPherron and Siscoe [2004] to examine the statistical characteristics of interplanetary plasma/magnetic field and probability distribution function of geomagnetic activity indices for strong IMF Bs intervals. It is shown that the occurrence of long-duration, large-amplitude IMF Bs intervals, related with different solar wind transients (such as ICME, SIR), are preceded by and change with a distinctive set of other solar wind/IMF parameters. We find that solar wind speed is positively correlated with geomagnetic indices, and that strong IMF Bs is the key to trigger storm but not necessarily substorm. We also find that solar wind density weakly affects geomagnetic activity, and the response depends on different kinds of solar wind transients that include the strong IMF Bs-events. We also find that magnetospheric ULF waves are induced by both strong southward IMF intervals and solar wind dynamic pressure disturbances.

  5. 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.

  6. 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.

  7. Near- and far-field tsunamigenic effects on the Z component of the geomagnetic field during the Japanese event, 2011

    NASA Astrophysics Data System (ADS)

    Klausner, Virginia; Kherani, Esfhan A.; Muella, Marcio T. A. H.

    2016-02-01

    In this work, we examine the vertical component (Z) of the geomagnetic field observed by ground-based observatories during the tsunami event which happened on 11 March 2011. For this event, we have selected nine magnetic observatories distributed along the tsunami passage, covering up to 3000 km epicentral distance. The traveltime diagram of the magnetic disturbances is constructed and compared with the simulated tsunami traveltime diagram. From this comparison, we identify the amplified magnetic disturbances appearing during the tsunami arrival in the vicinity of these observatories. Moreover, mean absolute percentage error map is constructed to examine the cross correlations among different observatories and the amplified disturbances are found to be highly correlated. These features suggest that the amplified disturbances are tsunamigenic in nature. These results are in confirmation with the previous near-field studies, and they shed new insight into the tsunamigenic magnetic disturbances on near- and far-field distances from the epicenter.

  8. Geomagnetic storm's precursors observed from 2001 to 2007 with the Global Muon Detector Network (GMDN)

    NASA Astrophysics Data System (ADS)

    Rockenbach, M.; Dal Lago, A.; Gonzalez, W. D.; Munakata, K.; Kato, C.; Kuwabara, T.; Bieber, J.; Schuch, N. J.; Duldig, M. L.; Humble, J. E.; Al Jassar, H. K.; Sharma, M. M.; Sabbah, I.

    2011-08-01

    We use complementary observations from the prototype and expanded Global Muon Detector Network (GMDN) and the Advanced Composition Explorer (ACE) satellite to identify precursors of geomagnetic storm events. The GMDN was completed and started operation in March 2006 with the addition of the Kuwait detector, complementing the detectors at Nagoya, Hobart, and São Martinho da Serra. Analyzed geomagnetic storms sorted by their intensity as measured by the Disturbance storm-time (Dst) index. Between March 2001 and December 2007, 122 Moderate Storms (MS), 51 Intense Storms (IS), and 8 Super Storms (SS) were monitored by the GMDN. The major conclusions are (i) the percentage of the events accompanied by the precursors prior to the Sudden Storm Commencement (SSC) increases with increasing peak Dst, (ii) 15% of MSs, 30% of ISs, and 86% of SSs are accompanied by cosmic ray precursors observed on average 7.2 hours in advance of the SSC.

  9. HF Doppler oscillations during the geomagnetic storm of February 6-9, 1986

    NASA Astrophysics Data System (ADS)

    Ogawa, T.; Kainuma, S.; Katoh, C.

    Some results of HF Doppler (HFD) measurements during the large geomagnetic storm of February 6-9, 1986 are reported. In association with the storm sudden commencement at 1312 UT on February 6, HFD frequency deviations belonging to an SCF(+ -) type, which is believed to be caused by westward and subsequent eastward electric fields, were observed. Wave parameters of large-scale traveling ionospheric disturbances (period = 80-100 minutes, phase velocity = 440 m/s, and horizontal wavelength = 2100-2600 km), detected on the night of February 7, are almost completely consistent with those observed by the MU radar at Shigaraki. Very clear, sinusoidal HFD oscillations with a period of 2.5 minutes triggered by the sudden impulse at 1748 UT on February 9 were simultaneously accompanied by the geomagnetic pulsation. These HFD oscillations can be explained by the compressions and rarefactions of the ionospheric plasma due to the pulsation magnetic field.

  10. 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.

  11. 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

  12. Geomagnetic storm forecasts several hours ahead

    NASA Astrophysics Data System (ADS)

    Podladchikova, Tatiana; Petrukovich, Anatoli

    In this study we present a service implemented at Space Research Institute, Russia, providing an advance warning about the future geomagnetic storm magnitude (the negative peak Dst) using first geomagnetic storm indications. We demonstrate a clear relation between the solar wind parameters in the beginning of the storm development with the ultimate storm strength. For suddenly developing major storms that have essential influence on susceptible technological systems such as satellites, pipelines, power systems, and radio communications we predict lower and upper limits of the negative peak Dst. The high predictive potential of the proposed technique was confirmed by testing it on geomagnetic storms during the period 1995-2013. The advance warning time about the future geomagnetic storm strength on average achieves 5-6 hours and varies from 1 to 22 hours. The error of the peak Dst prediction does not exceed 25% with probability of 0.96. The false prediction probability does not exceed 0.03. Real-time predictions of the geomagnetic storm magnitude are updated every hour and published at http://spaceweather.ru

  13. On the geomagnetic jerk of 1969

    NASA Astrophysics Data System (ADS)

    McLeod, M. G.

    1985-05-01

    Courtillot et al. (1978) have first reported a sudden change in the slope of the first time derivatives of the geomagnetic field components which occurred around 1970. It was found that the change took place in a large part of the northern hemisphere. Malin and Hodder (1982) reported on studies which were conducted to determine whether this 1970 step change in the second time derivative of the geomagnetic field components, which they termed a geomagnetic 'jerk', was of internal or external origin. It was concluded that internal sources can give rise to changes in secular variation on time scales as short as one or two years and that these were the major factor in the geomagnetic jerk which occurred around 1970. The present paper provides new supporting evidence for the existence of a worldwide geomagnetic jerk, its (average) time of occurrence, and its internal nature. New estimates are given of the spherical harmonic coefficients of the jerk and of the pre-1969 and post-1969 secular acceleration.

  14. On the geomagnetic jerk of 1969

    NASA Technical Reports Server (NTRS)

    Mcleod, M. G.

    1985-01-01

    Courtillot et al. (1978) have first reported a sudden change in the slope of the first time derivatives of the geomagnetic field components which occurred around 1970. It was found that the change took place in a large part of the northern hemisphere. Malin and Hodder (1982) reported on studies which were conducted to determine whether this 1970 step change in the second time derivative of the geomagnetic field components, which they termed a geomagnetic 'jerk', was of internal or external origin. It was concluded that internal sources can give rise to changes in secular variation on time scales as short as one or two years and that these were the major factor in the geomagnetic jerk which occurred around 1970. The present paper provides new supporting evidence for the existence of a worldwide geomagnetic jerk, its (average) time of occurrence, and its internal nature. New estimates are given of the spherical harmonic coefficients of the jerk and of the pre-1969 and post-1969 secular acceleration.

  15. 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.

  16. 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.

  17. Monitoring the ionospheric total electron content variations over the Korean Peninsula using a GPS network during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Choi, Byung-Kyu; Lee, Sang-Jeong; Park, Jong-Uk

    2011-06-01

    We have established a regional ionospheric model (RIM) for investigating changes in the total electron content (TEC) over South Korea using 38 Korean GPS reference stations. The inverse distance weighted (IDW) interpolation method was applied to create a two-dimensional ionospheric map of vertical TEC units (TECU) based on a grid. To examine the diurnal patterns of ionospheric TEC over South Korea, we first processed the GPS data from a geomagnetically quiet period of 10 days. In a second step, we compared the estimated GPS-TEC variations with the changes in geomagnetic activity indices (the K p and D st indices) and the auroral electrojet index (AE) as a function of universal time (UT) on 4 and 20 November, 2003. The GPS-TEC responses for those storm events were proportional to the geomagnetic activity at this mid-latitude location. The sudden increases in ionospheric TEC (SITEC) caused by the geomagnetic storms were detected. The variations in GPS-TEC may help reveal the processes of ionospheric disturbances caused by geomagnetic storms.

  18. 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

  19. Episodes of Ionospheric Disturbances caused by Solar Activity probed using Long Wave Terrestrial Radio Signals

    NASA Astrophysics Data System (ADS)

    Shanmugha Sundaram, GA; Shaik, Manoj

    2016-07-01

    The dynamic spectral record of long wave (LW) radio signals (kHz band) had registered a disturbed condition of the ionosphere region involved with propagation of these signals. The reason for such signatures in the dynamic spectrogram can be accredited to the impact of Solar Energetic Particles (SEP) on the ionosphere along the propagation path of terrestrial long wave radiation, studied using the Multi-Hop propagation model. Points of reflection in the ionosphere directly above specific locations above the Earth where determined. Total Electron Content (TEC) values for such regions were obtained from interpretation of the global positioning system (GPS) data. From a comparisons of such results during periods when the Sun was quiet and active, the magnitude of ionosphere disturbance contributed by the various active solar phenomenae has been determined. The work reported here is based on the impact of Geomagnetic storm (K_{p}=6) on the TEC, that occurred on 16 April 2015. LW radio signals from transmitter locations operated by the United States Navy near Lualualei, Hawaii (Geomagnetic lat 21°25'13.38"}N, Geomagnetic long 158°09'14.35"W) and by France at Rosnay (Geomagnetic lat 46°42'47"N, Geomagnetic long 1°14'39"E) were monitored closely to know the extent of ionospheric impact.

  20. Surface electromagnetic impedance and geomagnetic activity: results of long term observation

    NASA Astrophysics Data System (ADS)

    Lemperger, István; Menvielle, Menvielle; Wesztergom, Viktor; Bencze, Pál; Szendrői, Judit; Novák, Attila; Kis, Árpád; Szalai, Sándor

    2014-05-01

    The magnetotelluric (MT) method is one of the most useful geophysical tool to discover even the deep subsurface structures. The target function of the MT data processing is the surface electromagnetic (EM) impedance. In case of practical MT exploration the surface EM impedance is computed based on a simplification related to the nature of the ionospheric source of the surface EM signals. Assuming that the ionospheric current systems result in homogeneous surface electromagnetic variations, the uncertainty of the computed surface electromagnetic impedance tensor depends only the duration of the EM observation. However the surface EM field can only be approached by plane waves in certain time periods and besides given uncertainty. The EM impedance may be sensitive to magnetospheric and -indirectly- interplanetary circumstances and solar activity. Four years continuous observation of telluric and surface geomagnetic components allowed to perform a representative survey to discover if geomagnetic activity has any effect on observed EM impedance tensor. Geomagnetic indices (Dst, ULF-index, ASY-H, SYM-H) have been used to classify dates according to geomagnetic activity. Processing to estimate the mean surface EM impedance tensor has been performed in each dataset, each class separately. The sensitivity and the characteristics of the answer of the EM impedance tensor to the geomagnetic disturbances seems to be definite. This presentation aims to briefly summarize the preliminary results of our study based on the unique dataset of the Széchenyi István Geophysical Obsevatory (Intermagnet code:NCK). In addition, pointing out the limitations of the routine way of practical MT data processing and interpretation is an important duty of this study. This study was supported by the TAMOP-4.2.2.C-11/1/KONV-2012-0015 (Earth-system) project sponsored by the EU and European Social Foundation.

  1. Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation

    NASA Astrophysics Data System (ADS)

    Gmitrov, Juraj

    2007-03-01

    Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K p indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (ΔBRS with ΔMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow ( K-index with ΔMPPG; r s=-0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect.

  2. Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation.

    PubMed

    Gmitrov, Juraj

    2007-03-01

    Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K ( p ) indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (DeltaBRS with DeltaMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow (K-index with DeltaMPPG; r (s)=-0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect. PMID:16983578

  3. 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.

  4. 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

  5. Geomagnetic anomaly detected at hydromagnetic wave frequencies

    NASA Astrophysics Data System (ADS)

    Meloni, A.; Medford, L. V.; Lanzerotti, L. J.

    1985-04-01

    We report the discovery, in northwestern Illinois, of a geomagnetic anomaly, using hydromagnetic wave frequencies as the source spectrum. Three portable magnetometer stations with computer-compatible digital data acquisition systems were operated in a longitude array at Piano and Ashton, Illinois, and Cascade, Iowa (total separation ˜200 km), in 1981-1982. Analysis of the natural geomagnetic field fluctuations in the hydromagnetic wave regime reveals that the vertical components of the detected fluctuations are essentially 180° out of phase between Plano/Ashton and Cascade for variations with periods ˜30-120 s. The observations can be modeled in terms of a shallow (˜10-20 km) north-south oriented geomagnetic anomaly of enhanced conductivity located between Ashton and Cascade, approximately parallel to the Mississippi River valley.

  6. 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.

  7. On the local operational geomagnetic index K calculation

    NASA Astrophysics Data System (ADS)

    Stankov, Stan; Stegen, Koen; Wautelet, Gilles; Warnant, Rene

    2010-05-01

    There is an ongoing demand for services that can provide real-time assessment of the (global and local) geomagnetic activity and identified as being of importance to the exploration geophysics, radio communications and precise position/navigation practices, space weather research and modelling, etc. Such services depend largely on the reduction of solar, geomagnetic and ionospheric observations to generate activity indices, one of the most widely used being the K index. The K index is a quasi-logarithmic index characterising the 3-hourly range in transient magnetic activity relative to the regular "quiet-day" activity for a single site location. A derivative "planetary" index (Kp), the mean standardized K index from several globally distributed stations, provides a convenient measure of the global geomagnetic activity. Computer-based derivation of K/Kp indices was a major step towards higher efficiency and lower costs. Nowadays, automated data acquisition, processing and generating the index in real time is mandatory for any reliable service. However, Kp may not be accurate enough when monitoring disturbances of smaller scale, so the local K index (derived from the nearest magnetic station/s) might be considered as the better choice. Moreover, the 3-hour time scale is much larger than the shorter characteristic time of localised ionospheric phenomena that are of particular interest to us. Our experience in developing a novel nowcast system for local operational geomagnetic index K calculation (K-LOGIC) will be presented. The system is based on a fully automated computer procedure for real-time digital magnetogram data acquisition, screening the dataset and removing the outliers, establishing the solar regular (Sr) variation of the geomagnetic field, calculating the K index, and issuing an alert if storm-level activity is indicated. This is a time-controlled (rather than event-driven) system delivering as regular output (time resolution set to 1 hour) the K value

  8. First geomagnetic measurements in the Antarctic region

    NASA Astrophysics Data System (ADS)

    Raspopov, O. M.; Demina, I. M.; Meshcheryakov, V. V.

    2014-05-01

    Based on data from literature and archival sources, we have further processed and analyzed the results of geomagnetic measurements made during the 1772-1775 Second World Expedition by James Cook and the 1819-1821 overseas Antarctic Expedition by Russian mariners Bellingshausen and Lazarev. Comparison with the GUFM historical model showed that there are systematic differences in the spatial structure of both the declination and its secular variation. The results obtained can serve as a basis for the construction of regional models of the geomagnetic field for the Antarctic region.

  9. 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.

  10. 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

  11. Geomagnetism and climate V: general conclusions

    NASA Astrophysics Data System (ADS)

    Mörner, N.-A.; Nevanlinna, H.; Dergachev, V.; Shumilov, O.; Raspopov, O.; Abrahamsen, N.; Pilipenko, O.; Trubikhin, V.; Gooskova, E.

    2003-04-01

    The shielding capacity of the Earth’s geomagnetic field is a prime factor regulating the flux into the atmosphere of galactic cosmic ray (in its turn controlling the 14C and 10Be production). This shielding capacity is controlled both by the Earth’s own geomagnetic field variability and by the Solar Wind variations. The Solar Wind interaction with the magnetosphere also affects the Earth’s rate of rotation (as recorded in the correlation between LOD and Sunspot activity). This opens for three possible lines of Solar Terrestrial interaction. (1) Changes in the total irradiance (known to be very small, however, over a full sun spot cycle). (2) Changes in cosmic ray flux reaching into the Earth’s atmosphere where it has the potential of affecting airglow and cloudiness (especially the cloudiness at a height in the order of 15 km). (3) Changes in the Earth’s rate of rotation affecting the oceanic circulation redistributing ocean-stored heat and water masses. The Spörer, Maunder and Dalton sun spot minima seem all to have led to periods of rotational acceleration pulling Arctic water down the European coasts and displacing the warm Gulf Stream towards Gibraltar. The geomagnetic field as regulator of cosmic ray flux and rotational potential is likely to have played a significant role even over longer time periods. It should be noted, however, the geometry of the Earth’s geomagnetic field cannot have differed very much due to frozen plasma conditions even at excursions and reversals. If the recorded sunspot and geomagnetic cycles are extrapolated into the future they predict a new low (“Little Ice Age”) in the years 2050 2100 (i.e. a scenario very different from that presented by IPCC). Our study of the relation between geomagnetism and climate has shown that geomagnetic field changes have played an important role in modulation Earth’s climate. These changes may originate from internal planetary sources (i.e. the Earth’s own geomagnetic field) as well

  12. Geomagnetic storm fields near a synchronous satellite.

    NASA Technical Reports Server (NTRS)

    Kawasaki, K.; Akasofu, S. I.

    1971-01-01

    An apparent early recovery of the main phase of geomagnetic storms at the distance of the synchronous satellite is examined in terms of changing electric current distributions in the magnetosphere during magnetic storms. It is suggested that a rapid recession of the edge of the plasma sheet (after the advance toward the earth during an early epoch of the main phase) is partly responsible for the early recovery. Relevant plasma sheet variations during geomagnetic storms are found to be in agreement with the inferred variations.

  13. A simple statistical model for geomagnetic reversals

    NASA Technical Reports Server (NTRS)

    Constable, Catherine

    1990-01-01

    The diversity of paleomagnetic records of geomagnetic reversals now available indicate that the field configuration during transitions cannot be adequately described by simple zonal or standing field models. A new model described here is based on statistical properties inferred from the present field and is capable of simulating field transitions like those observed. Some insight is obtained into what one can hope to learn from paleomagnetic records. In particular, it is crucial that the effects of smoothing in the remanence acquisition process be separated from true geomagnetic field behavior. This might enable us to determine the time constants associated with the dominant field configuration during a reversal.

  14. High-latitude geomagnetic effects of the main phase of the geomagnetic storm of November 24, 2001 with the Northern direction of IMF

    NASA Astrophysics Data System (ADS)

    Kleimenova, N. G.; Gromova, L. I.; Dremukhina, L. A.; Levitin, A. E.; Zelinsky, N. R.; Gromov, S. V.

    2015-03-01

    The high-latitude geomagnetic events that occurred under extreme space weather conditions during the non-typical development of the main phase of the strong magnetic storm of November 24, 2001 were studied. The development of the main phase was or ceased by a sharp turn of the IMF to the north and the appearance of extremely high (up to about 60 nT) positive IMF Bz values; in this period, high alternating IMF By values were observed (from +40 to -40 nT) against a high dynamic pressure of the solar wind, with sharp bursts up to 50-70 nPa. This resulted in the cessation of nighttime substorms. Magnetic disturbances were recorded on the Earth's surface only in the daytime sector of polar latitudes as a very strong magnetic bay with amplitude of about 2000 nT. According to model calculations, a sharp intensification of field-aligned currents of the NBZ system was noted in that region. The onset of the daytime polar magnetic bay was accompanied by an auroral burst and strong local geomagnetic pulsations in the ˜(2-7) mHz band. Bursts of fluctuations in the solar wind and IMF were not accompanied by simultaneous bursts in ground based high-latitude geomagnetic pulsations, that is, the direct penetration of solar wind and IMF pulsations into the magnetosphere was unlikely to occur. The daytime polar geomagnetic pulsations observed on the Earth's surface could be caused by variations in high-latitude field-aligned currents, which were excited in a turbulent daytime boundary layer as a result of interaction with solar wind inhomogeneities.

  15. 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

  16. Calibration of historical geomagnetic observations from Prague-Klementinum

    NASA Astrophysics Data System (ADS)

    Hejda, Pavel

    2015-04-01

    The long tradition of geomagnetic observations on the Czech territory dates back to 1839, when regular observations were started by Karl Kreil at the Astronomical Observatory Prague-Klementinum. Observations were carried out manually, at the beginning more than ten times per day and the frequency later decreased to 5 daily observations. Around the turn of century the observations became to be disturbed by the increasing urban magnetic noise and the observatory was closed down in 1926. The variation measurements were completed by absolute measurements carried out several times per year. Thanks to the diligence and carefulness of Karl Kreil and his followers all results were printed in the yearbooks Magnetische und meteorologische Beobachtungen zu Prag and have thus been saved until presence. The entire collection is kept at the Central Library of the Czech Academy of Sciences. As the oldest geomagnetic data have been recently recognized as an important source of information for Space Weather studies, digitization and analysis of the data have been now started. Although all volumes have been scanned with the OCR option, the low quality of original books does not allow for an automatic transformation to digital form. The data were typed by hand to Excel files with a primary check and further processed. Variation data from 1839 to 1871 were published in measured units (scales of divisions). Their reduction to physical units was not as straight forward as we are used in recent observatories. There were several reasons: (i) the large heavy magnetic rods were not as stable as recent systems, (ii) the absolute measurements of horizontal components were carried out by the genius but rather complicated Gauss method, (iii) the intervals between absolute measurements was on the scale of months and eventual errors were not recognized timely. The presentation will discuss several methods and give examples how to cope with the problem.

  17. Natural magnetic disturbance fields, not precursors, preceding the Loma Prieta earthquake

    NASA Astrophysics Data System (ADS)

    Campbell, Wallace H.

    2009-05-01

    Available records of the magnetic indices Dst and ap together with standard observatory recordings of 1-min field levels were examined for the period preceding the earthquake of October 1989, centered near Loma Prieta, California. The magnetic records showed that the Fraser-Smith et al. (1990) report claiming the existence of a 100-s (ultralow frequency) geomagnetic field precursor signal at Corralitos, California, foretelling a nearby earthquake is not valid. My study shows that the Stanford ULF signal was not local but rather widespread throughout the western United States and, therefore, expected to be due to a coincidental geomagnetic solar-terrestrial disturbance field.

  18. Observations in the South Atlantic Geomagnetic Anomaly with Intercosmos-Bulgaria-1300 during a geomagnetic storm

    SciTech Connect

    Gogoshev, M.M.; Gogosheva, TS.N.; Kostadinov, I.N.; Markova, T.I.; Kisovski, S.

    1985-01-01

    The region of South Atlantic Geomagnetic Anomaly was investigated by the Intercosmos-Bulgaria-1300 satellite, launched on August 7, 1981. On the basis of data obtained from 15 orbits during increased geomagnetic activity in August 1981, a map of the Anomaly was elaborated. Two centers of activity were identified. By means of the EMO-5 electrophotometer on board the Intercosmos-Bulgaria-1300 satellite, the atmosphere glow in lines 5577 A, 6300 A and 4278 A was studied. 11 references.

  19. Nonlinear Behavior of the Geomagnetic Fluctuations Recorded in Different Geomagnetic Latitudes

    NASA Astrophysics Data System (ADS)

    Kovacs, P.; Heilig, B.; Koppan, A.; Vadasz, G.; Echim, M.

    2014-12-01

    The paper concerns with the nonlinear properties of geomagnetic variations recorded in different geomagnetic latitudes, in the years of solar maximum and minimum. For the study, we use the geomagnetic time-series recorded by some of the stations of the EMMA quasi-meridional magnetometer network, established for pulsation study, in September 2001. The stations are located approx. along the magnetic meridian of 100 degree, and the sampling frequency of the series is 1 Hz. It is argued that the geomagnetic field exhibits nonlinear intermittent fluctuations in certain temporal scale range. For quantitatively investigating the scaling ranges and the variation of intermittent properties with latitude and time, we analyse the higher order moments of the time records (probability density function or structure function analyses). The multifractal or self-similar scaling of the fluctuations is investigated via the fitting of the P model to structure function scaling exponents. We also study the power-law behaviour of the power-spectral density functions of the series in order to evaluate the possible inertial frequency (and temporal) range of the geomagnetic field and compare them with the scaling ranges of structure functions. The range where intermittent geomagnetic variation is found falls typically between 100 and 20.000 s, i.e. covers the temporal range of the main phases of geomagnetic storms. It is shown that the intensity of intermittent fluctuations increases from solar minimum to solar maximum. The expected increase in the level of intermittency with the geomagnetic latitude can be evidenced only in the years of solar minimum. The research leading to these results has received funding from the European Community's Seventh Framework Programme ([FP7/2007-2013]) under grant agreement n° 313038/STORM.

  20. 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.

  1. 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.

  2. Geomagnetic storms: historical perspective to modern view

    NASA Astrophysics Data System (ADS)

    Lakhina, Gurbax S.; Tsurutani, Bruce T.

    2016-12-01

    The history of geomagnetism is more than 400 years old. Geomagnetic storms as we know them were discovered about 210 years ago. There has been keen interest in understanding Sun-Earth connection events, such as solar flares, CMEs, and concomitant magnetic storms in recent times. Magnetic storms are the most important component of space weather effects on Earth. We give an overview of the historical aspects of geomagnetic storms and the progress made during the past two centuries. Super magnetic storms can cause life-threatening power outages and satellite damage, communication failures and navigational problems. The data for such super magnetic storms that occurred in the last 50 years during the space era is sparce. Research on historical geomagnetic storms can help to create a database for intense and super magnetic storms. New knowledge of interplanetary and solar causes of magnetic storms gained from spaceage observations will be used to review the super magnetic storm of September 1-2, 1859. We discuss the occurrence probability of such super magnetic storms, and the maximum possible intensity for the effects of a perfect ICME: extreme super magnetic storm, extreme magnetospheric compression, and extreme magnetospheric electric fields.

  3. Earthquake waves and the geomagnetic dynamo.

    PubMed

    Mullan, D J

    1973-08-10

    It is proposed that earthquake waves energize the geomagnetic dynamo. Fluid motions generated by earthquakes may have enough energy to be in equipartition with fields as large as 100 gauss. Seismic waves from meteoritic impacts with energies sufficient to reverse the field occur every 170,000 years. PMID:17777805

  4. Enhancing model based forecasting of geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Webb, Alla G.

    Modern society is increasingly dependent on the smooth operation of large scale technology supporting Earth based activities such as communication, electricity distribution, and navigation. This technology is potentially threatened by global geomagnetic storms, which are caused by the impact of plasma ejected from the Sun upon the protective magnetic field that surrounds the Earth. Forecasting the timing and magnitude of these geomagnetic storms is part of the emerging discipline of space weather. The most severe geomagnetic storms are caused by magnetic clouds, whose properties and characteristics are important variables in space weather forecasting systems. The methodology presented here is the development of a new statistical approach to characterize the physical properties (variables) of the magnetic clouds and to examine the extent to which theoretical models can be used in describing both of these physical properties, as well as their evolution in space and time. Since space weather forecasting is a complex system, a systems engineering approach is used to perform analysis, validation, and verification of the magnetic cloud models (subsystem of the forecasting system) using a model-based methodology. This research demonstrates that in order to validate magnetic cloud models, it is important to categorize the data by physical parameters such as velocity and distance travelled. This understanding will improve the modeling accuracy of magnetic clouds in space weather forecasting systems and hence increase forecasting accuracy of geomagnetic storms and their impact on earth systems.

  5. Simulation of the Geomagnetic Cut-off with GEANT using the International Geomagnetic Reference Field

    NASA Astrophysics Data System (ADS)

    Wentz, J.; Bercuci, A.; Vulpescu, B.

    2001-08-01

    The International Geomagnetic Reference Field is used in a GEANT3 simulation to calculate the geomagnetic cut-off for cosmic rays entering in the Earth's magnetic field. The calculations are done in the back tracking method, where antiprotons start from the top of atmosphere and are tracked to outer space. The geomagnetic cut-off functions are estimated in momentum steps of 0.2 GeV for 131 directions in 1655 locations covering in a nearly equidistant grid the surface of the Earth. For special locations, where neutrino or low energy muon data have been measured, the cut-off functions are calculated in a fine grid of 21601 directions. The estimated geomagnetic cut-offs can be verified by the experimental results for primary protons and helium nuclei measured in different geomagnetic latitudes during the shuttle mission of the AMS prototype. These precise tables of the geomagnetic cut-off can be used in the frame of the CORSIKA code to calculate atmospheric muon and neutrino fluxes.

  6. 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.

  7. The geomagnetic storms of 2015: Statistical analysis and forecasting results

    NASA Astrophysics Data System (ADS)

    Paouris, Evangelos; Gerontidou, Maria; Mavromichalaki, Helen

    2016-04-01

    The year 2015 was characterized by long geomagnetic quiet periods with a lot of geomagnetically active breaks although it is on the declining phase of the current solar cycle. As a result a number of geomagnetic storms in the G1 up to G4 scale were noticed. In this work the characteristics of these geomagnetic storms like the scale level, the origin of the storm (CME or CIR) and the duration have been studied. Furthermore, a statistical analysis of these events and a comparative study of the forecasting and the actual geomagnetic conditions are performed using data from the NOAA space weather forecasting center and from the Athens Space Weather Forecasting Center as well. These forecasting centers estimate and provide every day the geomagnetic conditions for the upcoming days giving the values of the geomagnetic index Ap. The forecasting values of Ap index for the year 2015 from these two centers and their comparison in terms of the actual values are discussed.

  8. Aurora Boundaries Quantified by Geomagnetic Index

    NASA Astrophysics Data System (ADS)

    Carbary, J. F.

    2004-12-01

    Various operational systems require information on the location and intensity of the aurora. A statistical model of the aurora is given using global images from the Ultraviolet Imager (UVI) on the Polar satellite. The equatorward (EQ), poleward (PO) and peak (PK) boundaries of the auroral oval are determined. using UVI images averaged into 1° x1° spatial bins according to common geomagnetic indices such as Kp, AE, AL, and PCI. From these bin-averaged images, latitude intensity profiles at 1 hour MLT intervals are constructed by interpolation. A background is subtracted for each profile, and the EQ, PO, and PK boundary latitudes are found from the corrected profile. (The PK boundary is the maximum, and the EQ and PO boundaries are threshold locations of fixed irradiances such as 1, 2, or 4 photons/cm2s.) Several months of images during the winter and summer of 1997 were used to statistically quantify the boundaries at various levels of geomagnetic activity given by the several indices. As expected, the higher the level of activity, the wider and more expanded the oval. More importantly, the boundaries are functionally related to the indices at any local time. These functional relations can then be used to determine the auroral location at any level of geomagnetic activity given by the indices. Thus, given a level of geomagnetic activity, one can find the boundaries of the oval as defined on the basis of intensity. By monitoring the relevant geomagnetic index, an operational system can then easily compute the expected oval location and judge its impact on performance. The optimum indices that best define the oval will be discussed.

  9. Effect of local perturbations of the geomagnetic field on cosmic ray cutoff rigidities at Jungfraujoch and Kiel

    SciTech Connect

    Flueckiger, E.O.; Smart, D.F.; Shea, M.A.

    1983-09-01

    We have investigated the effect of local perturbations of the geomagnetic field on the vertical cosmic ray cutoff rigidities at Jungfraujoch and Kiel as representative mid-latitude neutron monitor stations. The main, effective, and Stoermer vertical cutoff rigidities and their changes were determined by utilizing the trajectory-tracing technique in a magnetic field which is modeled as a simple dipole field to which the disturbance field is superposed. It was found that the cosmic ray cutoff rigidities are most sensitive to variations of the z component of the geomagnetic field at geomagnetic latitudes -20/sup 0/<..lambda..<+30/sup 0/ and at longitudes within 90/sup 0/ to the east of these northern hemisphere stations. Furthermore, cutoff rigidity variations at Kiel are predominantly due to changes of the geomagnetic field within geocentric distances 2.5R/sub E/disturbances within 1R/sub E/geomagnetic perturbations the rigidity corresponding to the first ''discontinuity band'' of the rigidity spectrum is an extremely useful parameter.

  10. The 27 day solar rotational effect on mesospheric nighttime OH and O3 observations induced by geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Fytterer, T.; Santee, M. L.; Sinnhuber, M.; Wang, S.

    2015-09-01

    Observations performed by the Earth Observing System Microwave Limb Sounder instrument on board the Aura satellite from 2004 to 2009 (2004 to 2014) were used to investigate the 27 day solar rotational cycle in mesospheric OH (O3) and the physical connection to geomagnetic activity. Data analysis was focused on nighttime measurements at geomagnetic latitudes connected to the outer radiation belts (55°N/S-75°N/S). The applied superposed epoch analysis reveals a distinct 27 day solar rotational signal in OH and O3 during winter in both hemispheres at altitudes >70 km. The OH response is positive and in-phase with the respective geomagnetic activity signal, lasting for 1-2 days. In contrast, the O3 feedback is negative, delayed by 1 day, and is present up to 4 days afterward. Largest OH (O3) peaks are found at ~75 km, exceeding the 95% significance level and the measurement noise of <2% (<0.5%), while reaching variations of +14% (-7%) with respect to their corresponding background. OH at 75 km is observed to respond to particle precipitation only after a certain threshold of geomagnetic activity is exceeded, depending on the respective OH background. The relation between OH and O3 at 75 km in both hemispheres is found to be nonlinear. In particular, OH has a strong impact on O3 for relatively weak geomagnetic disturbances and accompanying small absolute OH variations (<0.04 ppb). In contrast, catalytic O3 depletion is seen to slow down for stronger geomagnetic variations and OH anomalies (0.04-0.13 ppb), revealing small variations around -0.11 ppm.

  11. An alternative way to identify local geomagnetically quiet days: a case study using wavelet analysis

    NASA Astrophysics Data System (ADS)

    Klausner, Virginia; Reinaldo Rodriguez Papa, Andrés; Cândido, Cláudia Maria Nicole; Oliveira Domingues, Margarete; Mendes, Odim

    2016-04-01

    This paper proposes a new method to evaluate geomagnetic activity based on wavelet analysis during the solar minimum activity (2007). In order to accomplish this task, a newly developed algorithm called effectiveness wavelet coefficient (EWC) was applied. Furthermore, a comparison between the 5 geomagnetically quiet days determined by the Kp-based method and by wavelet-based method was performed. This paper provides a new insight since the geomagnetic activity indexes are mostly designed to quantify the extent of disturbance rather than the quietness. The results suggest that the EWC can be used as an alternative tool to accurately detect quiet days, and consequently, it can also be used as an alternative to determine the Sq baseline to the current Kp-based 5 quietest days method. Another important aspect of this paper is that most of the quietest local wavelet candidate days occurred in an interval 2 days prior to the high-speed-stream-driven storm events. In other words, the EWC algorithm may potentially be used to detect the quietest magnetic activity that tends to occur just before the arrival of high-speed-stream-driven storms.

  12. Comparison of K-index Calculations between Several Geomagnetic Stations during IQDs and IDDs

    NASA Astrophysics Data System (ADS)

    Hwang, Junga; Kim, Hang-Pyo; Park, Young-Deuk

    2013-09-01

    BOH magnetometer was installed at Mt. Bohyun in 2007 and has provided continuous dataset for 3-axis geomagnetic field over the South Korea. We have calculated real-time K-index based on BOH magnetic field data using well-known FMI method. Local K-index is calculated eight times a day, per every three hours. To calculate K-index, it is critical to get the Quiet Day Curve (QDC). For QDC calculation, we take the previous one month's average of H-component. In this paper, we compared four geomagnetic stations' magnetic field data over South Korea and Japan and K-indices of each stations; Bohyun, Gangneung, Jeju, and Kakioka for two years data, 2011-2012. To investigate the difference depending on the latitude, longitude and local time in more detail, we compare K-index on International Quiet Days (IQDs) and International Disturbed Days (IDDs). As a result, we report the correlation between local K-indices are higher than those between Kp and local K-indices, and the correlation is much better after sunset than after sunrise. As the geomagnetic activity becomes stronger, the correlation between the local K-indices and global Kp-index become higher.

  13. Equatorial electrojet in the Indian region during the geomagnetic storm of 13-14 November 1998

    NASA Astrophysics Data System (ADS)

    Chandra, H.; Rastogi, R. G.; Choudhary, R. K.; Sharma, Som

    2016-04-01

    The geomagnetic storm of November 1998 is a unique event where IMF-Bz remained southward with values exceeding -15 nT for more than a day. The SYM/H index decreased from about 07 hr on 13 November 1998 reaching a minimum of about -120 nT around midnight of 13-14 November 1998. Features of the equatorial electrojet in the Indian region are studied during the geomagnetic storm event of 13-14 November 1998, based on the geomagnetic data from the chain of observatories in India. Sudden northward turning of IMF-Bz for a very short duration around 08 hr on 13 November 1998 resulted in a small and very short duration counter electrojet. A strong (-50 nT) and a long duration counter electrojet, right from 08 to 13 hr on 14 November 1998 was observed resulting in the absence of equatorial Es at Thumba. Absence of the equatorial ionization anomaly was also observed as seen from the ionograms over Thumba and ionspheric data from Ahmedabad. The delayed effect on 14 November 1998 is due to the disturbance dynamo effect.

  14. Classification of Regional Ionospheric Disturbances Based on Support Vector Machines

    NASA Astrophysics Data System (ADS)

    Begüm Terzi, Merve; Arikan, Feza; Arikan, Orhan; Karatay, Secil

    2016-07-01

    Ionosphere is an anisotropic, inhomogeneous, time varying and spatio-temporally dispersive medium whose parameters can be estimated almost always by using indirect measurements. Geomagnetic, gravitational, solar or seismic activities cause variations of ionosphere at various spatial and temporal scales. This complex spatio-temporal variability is challenging to be identified due to extensive scales in period, duration, amplitude and frequency of disturbances. Since geomagnetic and solar indices such as Disturbance storm time (Dst), F10.7 solar flux, Sun Spot Number (SSN), Auroral Electrojet (AE), Kp and W-index provide information about variability on a global scale, identification and classification of regional disturbances poses a challenge. The main aim of this study is to classify the regional effects of global geomagnetic storms and classify them according to their risk levels. For this purpose, Total Electron Content (TEC) estimated from GPS receivers, which is one of the major parameters of ionosphere, will be used to model the regional and local variability that differs from global activity along with solar and geomagnetic indices. In this work, for the automated classification of the regional disturbances, a classification technique based on a robust machine learning technique that have found wide spread use, Support Vector Machine (SVM) is proposed. SVM is a supervised learning model used for classification with associated learning algorithm that analyze the data and recognize patterns. In addition to performing linear classification, SVM can efficiently perform nonlinear classification by embedding data into higher dimensional feature spaces. Performance of the developed classification technique is demonstrated for midlatitude ionosphere over Anatolia using TEC estimates generated from the GPS data provided by Turkish National Permanent GPS Network (TNPGN-Active) for solar maximum year of 2011. As a result of implementing the developed classification

  15. Ionospheric disturbances at the equatorial anomaly crest region during the March 1989 magnetic storms

    SciTech Connect

    Yinn-Nien Huang; Kang, Cheng )

    1991-08-01

    On March 6, 1989, the largest sunspot group since 1982 came into view as it moved out of the eastern limb of the Sun. It was highly active during March8-18, and a great many transient ionospheric and geomagnetic variations were triggered by this sunspot group. The intensive ionospheric observations at Lunping Observatory and Chungli Ionosphere Station during this period recorded 30 solar flares manifested as shortwave fade-outs, sudden frequency deviations, and solar flare effects and three storm sudden commencement (SSC)-tupe geomagnetic storms, among which the March 13 SSC-type geomagnetic storm triggered an unusually severe ionospheric disturbance. The ionospheric total electron content, the critical frequency of the F{sub 2} layer, f{sub o}F{sub 2}, and the virtual heights at given frequencies all show wavelike up-and-down oscillations of the ionosphere. This oscillatory ionospheric motion is explained as due to the compression and expansion of the plasmasphere.

  16. Effects of geliogeophysical disturbances in haemorheological parameters of human

    NASA Astrophysics Data System (ADS)

    Ionova, V.; Sergeenko, N.; Sazanova, E.

    The changes of the rheological characteristics of blood at healthy people and patients with cerebrum-vascular pathology during 23 geomagnetic disturbances were studied. The analysis of dynamics of haemorheological parameters of both human groups has shown that the most of parameters are beginning statistically authentically to fall outside the normal limits already prior the beginning of the magnetic disturbance, others - per day of a beginning of disturbance. This fact specifies at an increase of variability for functional activity of blood cell in conditions of geomagnetic disturbance and allows to assume presence of direct influences of an environmental physical processes at the blood cell. The deterioration of deformation properties of erythrocytes is observed in the blood of people. The analysis of the data has resulted in occurrence of a hypothesis about appearance of instability at thrombosis-vascular part of haemostasis under influence of variation of electromagnetic field in during of magnetospheric disturbances. Such effect can be caused as direct and indirect action of an electrîmagnetic field of the Earth on the cells of blood. Haemoglobin of erythrocytes includes atoms of iron, having a deflection of the magnetic moment. In the cells, which had their erythrocytes membrane under influence of an electrîmagnetic field, had diminution of electrical mobility, that can influence the dynamics of physiological process of aggregation --disaggregation of erythrocytes in a stream of blood. Another channel of influence of geomagnetic disturbances on rheological property of blood can be connected with the action of electrîmagnetic fields through synchronization of rhythms of electromagnetic oscillations of cells of central nervous system. From the entire spectrum of an electrîmagnetic field apparent on the surface of the Earth, biologically effective factor is in a range of ultralow frequencies from 0,0001 up to 100 Ãö. The biorhythms of the brain, such as an

  17. Compensation of an attitude disturbance torque caused by magnetic substances in LEO satellites

    NASA Astrophysics Data System (ADS)

    Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki

    This research considers an attitude disturbance torque caused by ferromagnetic substances in a LEO satellite. In most LEO satellite missions, a gravity gradient torque, solar pressure torque, aerodynamic torque, and magnetic dipole moment torque are considered for their attitude control systems, however, the effect of the ferromagnetic substances causing a disturbance torque in the geomagnetic field is not considered in previous satellite missions. The ferromagnetic substances such as iron cores of MTQs and a magnetic hysteresis damper for a passive attitude control system are used in various small satellites. These substances cause a disturbance torque which is almost the same magnitude of the dipole magnetic disturbance and the dominant disturbance in the worst cases. This research proposes a method to estimate and compensate for the effect of the ferromagnetic substances using an extended Kalman filter. From simulation results, the research concludes that the proposed method is useful and attractive for precise attitude control for LEO satellite missions.

  18. Coincident 1.3-year Periodicities in the ap Geomagnetic Index and the Solar Wind

    NASA Technical Reports Server (NTRS)

    Paularena, K. I.; Szabo, A.; Richardson, J. D.

    1995-01-01

    Recent observations show an approximately 1.3-year period in the speed of the solar wind detected by the IMP 8 and Voyager 2 spacecraft. A similar period is also seen in the north-south (GSE) component of the magnetic field observed by IMP 8. Since both parameters are commonly used as input to models of geomagnetic activity, the 'ap' index (a measure of geomagnetic disturbance) is examined to look for this periodicity. The Lomb-Scargle periodogram method is used on the ap, plasma, and magnetic field data during the 1973-1994 time range. A dynamic FFT periodogram method is also used to analyze the ap data during this time, as well as to look for periods present between 1932 and 1972. A clear 1.3-year periodicity is present in the post-1986 data when the same period is observed in the plasma and field data. The V(2)B(zsm) and V(2)B(s) proxies for geomagnetic activity also show this periodicity. However, the southward (GSM) component of the magnetic field does not have a 1.3-year period, and neither do solar wind or ap data from 1973-1985. This demonstrates that the ap geomagnetic index can act as a proxy for solar wind periodicities at this time scale. Historic ap data are examined, and show that a similar periodicity in ap exists around 1942. Since auroral data show a 1.4-year periodicity, all these similar periods may result from a common underlying solar mechanism.

  19. Steady induction effects in geomagnetism. Part 1A: Steady motional induction of geomagnetic chaos

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    1992-01-01

    Geomagnetic effects of magnetic induction by hypothetically steady fluid motion and steady magnetic flux diffusion near the top of Earth's core are investigated using electromagnetic theory, simple magnetic earth models, and numerical experiments with geomagnetic field models. The problem of estimating a steady fluid velocity field near the top of Earth's core which induces the secular variation indicated by broad-scale models of the observed geomagnetic field is examined and solved. In Part 1, the steady surficial core flow estimation problem is solved in the context of the source-free mantle/frozen-flux core model. In the first paper (IA), the theory underlying such estimates is reviewed and some consequences of various kinematic and dynamic flow hypotheses are derived. For a frozen-flux core, fluid downwelling is required to change the mean square normal magnetic flux density averaged over the core-mantle boundary. For surficially geostrophic flow, downwelling implies poleward flow. The solution of the forward steady motional induction problem at the surface of a frozen-flux core is derived and found to be a fine, easily visualized example of deterministic chaos. Geomagnetic effects of statistically steady core surface flow may well dominate secular variation over several decades. Indeed, effects of persistent, if not steady, surficially geostrophic core flow are described which may help explain certain features of the present broad-scale geomagnetic field and perhaps paleomagnetic secular variation.

  20. Geomagnetic variations and solar activity relationship in the South Atlantic Geomagnetic Anomaly -SAMA

    NASA Astrophysics Data System (ADS)

    Claudir da Silva, Andirlei; Schuch, Nelson Jorge; Babulal Trivedi, Nalin; Frigo, Everton; Rigon Silva, Willian; Souza Savian, Fernando; Ronan Coelho Stekel, Tardelli; Espindola Antunes, Cassio; de Siqueira, Josemar

    Comparative studies between the ACE satellite's solar wind parameters (speed and density of the solar plasma ) and the geomagnetic variations recorded in the Southern Space Observatory -SSO/CRS/INPE -MCT, São Martinho da Serra, (29,43° S, 53,82° W, 488m a.s.l.), RS, Brazil, a were performed. The three orthogonal geomagnetic field components data were acquired with a fluxgate magnetometer with 0.5Hz acquisition rate. Comparisons between the temporal evolution of the geomagnetic field intensity and the solar wind parameters for different phases of the solar cycle were analyzed. It was possible to identify fast changes in the geomagnetic field which may be correlated with stronger or wicker solar activity with important effects around midday in the local Ionosphere. This fact confirm the existence of relationships between the local geomagnetic variations and the solar activity. The periods of higher solar activity are related to a significant increasing in the flow of electrically charged particles in the atmosphere. As consequence of the physical and chemical phenomena, associated to these particles flow increases, are damages in satellites that orbit this region, as well as the induced electric currents in the Earth surface that causes damages in the electric power systems.

  1. Detection of explosive events by monitoring acoustically-induced geomagnetic perturbations

    SciTech Connect

    Lewis, J P; Rock, D R; Shaeffer, D L; Warshaw, S I

    1999-10-07

    The Black Thunder Coal Mine (BTCM) near Gillette, Wyoming was used as a test bed to determine the feasibility of detecting explosion-induced geomagnetic disturbances with ground-based induction magnetometers. Two magnetic observatories were fielded at distances of 50 km and 64 km geomagnetically north from the northernmost edge of BTCM. Each observatory consisted of three separate but mutually orthogonal magnetometers, Global Positioning System (GPS) timing, battery and solar power, a data acquisition and storage system, and a three-axis seismometer. Explosions with yields of 1 to 3 kT of TNT equivalent occur approximately every three weeks at BTCM. We hypothesize that explosion-induced acoustic waves propagate upward and interact collisionally with the ionosphere to produce ionospheric electron density (and concomitant current density) perturbations which act as sources for geomagnetic disturbances. These disturbances propagate through an ionospheric Alfven waveguide that we postulate to be leaky (due to the imperfectly conducting lower ionospheric boundary). Consequently, wave energy may be observed on the ground. We observed transient pulses, known as Q-bursts, with pulse widths about 0.5 s and with spectral energy dominated by the Schumann resonances. These resonances appear to be excited in the earth-ionosphere cavity by Alfven solitons that may have been generated by the explosion-induced acoustic waves reaching the ionospheric E and F regions and that subsequently propagate down through the ionosphere to the atmosphere. In addition, we observe late time (> 800 s) ultra low frequency (ULF) geomagnetic perturbations that appear to originate in the upper F region ({approximately}300 km) and appear to be caused by the explosion-induced acoustic wave interacting with that part of the ionosphere. We suggest that explosion-induced Q-bursts may be discriminated from naturally occurring Q-bursts by association of the former with the late time explosion-induced ULF

  2. Geomagnetic Indices Variations And Human Physiology

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.

    2007-12-01

    A group of 86 volunteers was examined on each working day in autumn 2001 and in spring 2002. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were registered. Pulse pressure (PP) was calculated. Data about subjective psycho-physiological complaints (SPPC) were also gathered. Altogether 2799 recordings were obtained. ANOVA was employed to check the significance of influence of daily amplitude of H-component of local geomagnetic field, daily planetary Ap-index and hourly planetary Dst-index on the physiological parameters examined. Post hoc analysis was performed to elicit the significance of differences in the factors levels. Average values of SBP, DBP, PP and SPPC of the group were found to increase statistically significantly and biologically considerably with the increase of geomagnetic indices.

  3. Geomagnetic and Solar Indices Data at NGDC

    NASA Astrophysics Data System (ADS)

    Mabie, J. J.

    2012-12-01

    The National Geophysical Data Center, Solar and Terrestrial Physics Indices program is a central repository for global indices derived at numerous organizations around the world. These datasets are used by customers to drive models, evaluate the solar and geomagnetic environment, and to understand space climate. Our goal is to obtain and disseminate this data in a timely and accurate manner, and to provide the short term McNish-Lincoln sunspot number prediction. NGDC is in partnership with the NOAA Space Weather Prediction Center (SWPC), University Center for Atmospheric Sciences (UCAR), the Potsdam Helmholtz Center (GFZ), the Solar Indices Data Center (SIDC), the World Data Center for Geomagnetism Kyoto and many other organizations. The large number of available indices and the complexity in how they are derived makes understanding the data one of the biggest challenges for the users of indices. Our data services include expertise in our indices and related datasets to provide feedback and analysis for our global customer base.

  4. Geomagnetic modeling by optimal recursive filtering

    NASA Technical Reports Server (NTRS)

    Gibbs, B. P.; Estes, R. H.

    1981-01-01

    The results of a preliminary study to determine the feasibility of using Kalman filter techniques for geomagnetic field modeling are given. Specifically, five separate field models were computed using observatory annual means, satellite, survey and airborne data for the years 1950 to 1976. Each of the individual field models used approximately five years of data. These five models were combined using a recursive information filter (a Kalman filter written in terms of information matrices rather than covariance matrices.) The resulting estimate of the geomagnetic field and its secular variation was propogated four years past the data to the time of the MAGSAT data. The accuracy with which this field model matched the MAGSAT data was evaluated by comparisons with predictions from other pre-MAGSAT field models. The field estimate obtained by recursive estimation was found to be superior to all other models.

  5. Does a localized plasma disturbance in the ionosphere evolve to electrostatic equilibrium? Evidence to the contrary

    NASA Astrophysics Data System (ADS)

    Cosgrove, Russell B.

    2016-01-01

    Electrostatic equilibrium must be achieved through electromagnetic evolution. From an initial state with nonzero neutral wind localized along the geomagnetic field, and with all other plasma and electromagnetic perturbations initially zero, evolution progresses from plasma velocity to electric field to magnetic field, where the last step can launch an Alfvén wave that transmits the electromagnetic disturbance along geomagnetic field lines. Without the Alfvén wave the disturbance does not map along geomagnetic field lines, and there is no semblance of electrostatic equilibrium. This paradigm is essentially the traditional magnetosphere/ionosphere coupling paradigm, except addressed to smaller-scale, local ionospheric phenomena. However, Alfvén waves have not been thoroughly studied in the context of the partially ionized, collisional ionospheric plasma, and so the full effects predicted by this modeling paradigm are not known. In this work we adopt the two-fluid equations and investigate whether the ionosphere supports Alfvén-type waves that can transmit disturbances along geomagnetic field lines and perform a wave analysis of the "lumped circuit" parameters normally used to characterize the ionosphere under electrostatic equilibrium. We find that under the wave analysis (1) the Pedersen conductivity is severely modified and has a negative real part at short wavelengths; (2) the mapping distance for electric fields is significantly modified, and there is a nonnegligible wavelength along the geomagnetic field; and (3) the load admittance seen by a localized dynamo is strongly reactive, causing a phase offset between electric field and current, as compared with that when the load is electrostatic.

  6. OI 630.0 nm Night Airglow Observations during the Geomagnetic Storm on November 20, 2003 at Kolhapur (P43)

    NASA Astrophysics Data System (ADS)

    Sharma, A. K.; et al.

    2006-11-01

    sharma_ashokkumar@yahoo.com The ground based photometric observations of OI 630 nm emission line have been carried out from Kolhapur station (Geog. Lat.16.8˚N, Geo. Long 74.2˚E), India during the period of the largest geomagnetic storm of the solar cycle 23 which occurred on 20 November 2003, with minimum Dst index 472 nT occurring around mid-night hours. We observed that on 19 November 2003 which was geomagnetically quiet day, the airglow activity of OI 630 nm emission was subdued and it was decreasing monotonically. However, on the night of November 20, 2003 the enhancement is observed during geomagnetic storm due to the increased electron density at the altitude of the F region which is related to the downward transport of electron from the plasmasphere to the F-region. Airglow intensity at OI 630.0 nm showed increase around midnight on November 21, 2003 but comparatively on a smaller scale. On this night the DST index was about 100 nT. This implies that the effect of the geomagnetic storm persisted on that night also. These observations have been explained by the penetration magnetospheric electric field to the low latitude region and the subsequent modulation of meridional wind during the magnetic disturbance at night.

  7. MAGSAT for geomagnetic studies over Indian region

    NASA Technical Reports Server (NTRS)

    Rastogi, R. G.; Bhargava, B. N.; Singh, B. P.; Rao, D. R. K.; Rangarajan, G. K.; Rajaram, R.; Roy, M.; Arora, B. R.; Seth, A. (Principal Investigator)

    1981-01-01

    Progress in the preparation of software for converting data tapes produced on an IBM system to data readable on a DEC-10 system, in the creation of awareness of the utility of MAGSAT data among users in India, and in making computer programs supplied by NASA operational on the DEC-10 system is reported. Papers presented to Indian users, at the IAGA fourth scientific assembly, at a symposium on interdisciplinary approaches to geomagnetism, and a paper published in Science Today are included.

  8. NOAA Plans for Geomagnetic Storm Observations

    NASA Astrophysics Data System (ADS)

    Diedrich, B. L.; Biesecker, D. A.; Mulligan, P.; Simpson, M.

    2012-12-01

    For many years, NOAA has issued geomagnetic storm watches and warnings based on coronal mass ejection (CME) imagery and in-situ solar wind measurements from research satellites. The NOAA Satellite and Information Service (NESDIS) recognizes the importance of this service to protecting technological infrastructure including power grids, polar air travel, and satellite navigation, so is actively planning to replace these assets to ensure their continued availability. NOAA, NASA, and the US Air Force are working on launching the first operational solar wind mission in 2014, the Deep Space Climate Observatory (DSCOVR), to follow NASA's Advanced Composition Explorer (ACE) in making solar wind measurements at the sun-Earth L1 for 15-60 minute geomagnetic storm warning. For continuing operations after the DSCOVR mission, one technology NOAA is looking at is solar sails that could greatly improve the lead time of geomagnetic storm warnings by stationkeeping closer to the sun than L1. We are working with NASA and private industry on the Sunjammer solar sail demonstration mission to test making solar wind measurements from a solar sail in the sun-Earth L1 region. NOAA uses CME imagery from the NASA/ESA Solar and Heliospheric Observatory (SOHO) and the NASA Solar Terrestrial Relations Observatory (STEREO) satellites to issue 1-3 day geomagnetic storm watches. For the future, NOAA worked with the Naval Research Laboratory (NRL) to develop a Compact Coronagraph (CCOR) through Phase A, and is studying ways to complete instrument development and test fly it for use in the future.

  9. Geomagnetic activity and Hale sector boundaries

    NASA Technical Reports Server (NTRS)

    Lundstedt, H.; Scherrer, P. H.; Wilcox, J. M.

    1981-01-01

    The variation of the geomagnetic activity index Ap at the IMF sector boundaries (+ to - and - to +) has been studied for three solar cycles, separating data into vernal and autumnal equinoxes. It was found that a reported increase in Ap as an effect of a Hale boundary can be better attributed to the occurrence of a negative IMF Bz component in the geocentric solar magnetospheric coordinate system and to the occurrence of high speed solar wind streams.

  10. Response of ionospheric electric fields at mid-low latitudes during geomagnetic sudden commencements

    NASA Astrophysics Data System (ADS)

    Takahashi, N.; Kasaba, Y.; Shinbori, A.; Nishimura, Y.; Kikuchi, T.; Ebihara, Y.; Nagatsuma, T.

    2014-12-01

    Geomagnetic sudden commencements (SCs) are known as one of the distinct magnetospheric disturbance phenomena triggered by solar wind disturbances. Many previous studies have focused on the generation mechanism of SCs by using in-situ observations and simulations. However, the global evolution of ionospheric electric fields has primarily been estimated from the ionospheric current. Although a few studies utilized electric field data from radar observations, the coverage is limited in time, and limited component of the electric field is obtained. In this study, we investigated the response and local time dependence of the ionospheric electric field at mid-low latitudes associated with 203 SCs occurred from 1999 to 2004 by the in-situ observation of the ROCSAT-1 spacecraft. We found that the ionospheric electric field associated with SCs instantaneously responds to geomagnetic fields regardless of spacecraft local time. Our statistical analysis also showed the instantaneous response of the electric field, which indicates the global instant transmission of the electric field from polar region. In contrast, peak times in the preliminary impulse (PI) and main impulse (MI) phases were different between the ionospheric electric field and equatorial geomagnetic field (20 sec in the PI phase). Based on a comparison to the ground-ionosphere waveguide model by Kikuchi [2014], this time lag is suggested to be due to the latitudinal difference of the ionospheric conductivity. After constructing the local time distribution of the SC amplitude, we found that the dayside feature was seen at 18-22 h even the ionospheric conductivity is lower than that at dayside. We performed a magnetohydrodynamic (MHD) simulation for an ideal SC. The result of the simulation showed that the electric potential distribution is asymmetric with respect to the noon-midnight meridian, which is similar to our observational result. It appears to result from the divergence of the Hall current under the non

  11. Solar generated quasi-biennial geomagnetic variation

    NASA Technical Reports Server (NTRS)

    Sugiura, M.; Poros, D. J.

    1977-01-01

    The existence of highly correlated quasi-biennial variations in the geomagnetic field and in solar activity is demonstrated. The analysis uses a numerical filter technique applied to monthly averages of the geomagnetic horizontal component and of the Zurich relative sunspot number. Striking correlations are found between the quasi-biennial geomagnetic variations determined from several magnetic observatories located at widely different longitudes, indicating a worldwide nature of the obtained variation. The correlation coefficient between the filtered Dst index and the filtered relative sunspot number is found to be -0.79 at confidence level greater than 99% with a time-lag of 4 months, with solar activity preceding the Dst variation. The correlation between the unfiltered data of Dst and of the sunspot number is also high with a similar time-lag. Such a timelag has not been discussed in the literature, and a further study is required to establish the mode of sun-earth relationship that gives this time delay.

  12. Domino model for geomagnetic field reversals.

    PubMed

    Mori, N; Schmitt, D; Wicht, J; Ferriz-Mas, A; Mouri, H; Nakamichi, A; Morikawa, M

    2013-01-01

    We solve the equations of motion of a one-dimensional planar Heisenberg (or Vaks-Larkin) model consisting of a system of interacting macrospins aligned along a ring. Each spin has unit length and is described by its angle with respect to the rotational axis. The orientation of the spins can vary in time due to spin-spin interaction and random forcing. We statistically describe the behavior of the sum of all spins for different parameters. The term "domino model" in the title refers to the interaction among the spins. We compare the model results with geomagnetic field reversals and dynamo simulations and find strikingly similar behavior. The aggregate of all spins keeps the same direction for a long time and, once in a while, begins flipping to change the orientation by almost 180 degrees (mimicking a geomagnetic reversal) or to move back to the original direction (mimicking an excursion). Most of the time the spins are aligned or antialigned and deviate only slightly with respect to the rotational axis (mimicking the secular variation of the geomagnetic pole with respect to the geographic pole). Reversals are fast compared to the times in between and they occur at random times, both in the model and in the case of the Earth's magnetic field. PMID:23410284

  13. AI techniques in geomagnetic storm forecasting

    NASA Astrophysics Data System (ADS)

    Lundstedt, Henrik

    This review deals with how geomagnetic storms can be predicted with the use of Artificial Intelligence (AI) techniques. Today many different Al techniques have been developed, such as symbolic systems (expert and fuzzy systems) and connectionism systems (neural networks). Even integrations of AI techniques exist, so called Intelligent Hybrid Systems (IHS). These systems are capable of learning the mathematical functions underlying the operation of non-linear dynamic systems and also to explain the knowledge they have learned. Very few such powerful systems exist at present. Two such examples are the Magnetospheric Specification Forecast Model of Rice University and the Lund Space Weather Model of Lund University. Various attempts to predict geomagnetic storms on long to short-term are reviewed in this article. Predictions of a month to days ahead most often use solar data as input. The first SOHO data are now available. Due to the high temporal and spatial resolution new solar physics have been revealed. These SOHO data might lead to a breakthrough in these predictions. Predictions hours ahead and shorter rely on real-time solar wind data. WIND gives us real-time data for only part of the day. However, with the launch of the ACE spacecraft in 1997, real-time data during 24 hours will be available. That might lead to the second breakthrough for predictions of geomagnetic storms.

  14. An Examination of Selected Geomagnetic Indices in Relation to the Sunspot Cycle

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2006-01-01

    Previous studies have shown geomagnetic indices to be useful for providing early estimates for the size of the following sunspot cycle several years in advance. Examined this study are various precursor methods for predicting the minimum and maximum amplitude of the following sunspot cycle, these precursors based on the aa and Ap geomagnetic indices and the number of disturbed days (NDD), days when the daily Ap index equaled or exceeded 25. Also examined is the yearly peak of the daily Ap index (Apmax), the number of days when Ap greater than or equal to 100, cyclic averages of sunspot number R, aa, Ap, NDD, and the number of sudden storm commencements (NSSC), as well the cyclic sums of NDD and NSSC. The analysis yields 90-percent prediction intervals for both the minimum and maximum amplitudes for cycle 24, the next sunspot cycle. In terms of yearly averages, the best regressions give Rmin = 9.8+/-2.9 and Rmax = 153.8+/-24.7, equivalent to Rm = 8.8+/-2.8 and RM = 159+/-5.5, based on the 12-mo moving average (or smoothed monthly mean sunspot number). Hence, cycle 24 is expected to be above average in size, similar to cycles 21 and 22, producing more than 300 sudden storm commencements and more than 560 disturbed days, of which about 25 will be Ap greater than or equal to 100. On the basis of annual averages, the sunspot minimum year for cycle 24 will be either 2006 or 2007.

  15. The Vector Matching Method in Geomagnetic Aiding Navigation

    PubMed Central

    Song, Zhongguo; Zhang, Jinsheng; Zhu, Wenqi; Xi, Xiaoli

    2016-01-01

    In this paper, a geomagnetic matching navigation method that utilizes the geomagnetic vector is developed, which can greatly improve the matching probability and positioning precision, even when the geomagnetic entropy information in the matching region is small or the geomagnetic contour line’s variety is obscure. The vector iterative closest contour point (VICCP) algorithm that is proposed here has better adaptability with the positioning error characteristics of the inertial navigation system (INS), where the rigid transformation in ordinary ICCP is replaced with affine transformation. In a subsequent step, a geomagnetic vector information fusion algorithm based on Bayesian statistical analysis is introduced into VICCP to improve matching performance further. Simulations based on the actual geomagnetic reference map have been performed for the validation of the proposed algorithm. PMID:27447645

  16. Isolated sleep paralysis, vivid dreams and geomagnetic influences: II.

    PubMed

    Conesa, J

    1997-10-01

    This report describes a test of the hypothesis that significant changes in the ambient geomagnetic field are associated with altered normal nighttime dream patterns. Specifically, it was predicted that there would be a greater incidence of isolated sleep, paralysis or vivid dreams with abrupt rises and falls of geomagnetic activity. The author's (JC) and a second subject's (KC) daily reports of dream-recall were analyzed in the context of daily fluctuations of geomagnetic activity (K indices). Two analyses of variance indicated (i) significantly higher geomagnetic activity three days before a recorded isolated sleep paralysis event and (ii) significantly lower geomagnetic activity three days before an unusually vivid dream took place. Conversely, geomagnetic activity did not fluctuate significantly for randomly selected days. Testing a large sample over time is required for confirmation and extension of this work. PMID:9347546

  17. Visualization of geomagnetic field for education and outreach

    NASA Astrophysics Data System (ADS)

    Hatakeyama, T.

    2010-12-01

    Since April 2007 in the project "MAGE" (Mapping Applications to Geomagnetic Environments) we publish tools for visualization of the geomagnetic field on the web. Now five kinds of the geomagnetic field flucuation (from observations and paleomagnetic results) and geodynamo models are freely downloadable from our website, http://mage-p.org/. Access the webpage, download the KML files and open them from Google Earth, then you can experience changing geomagnetic field lines and observations, inclinations, declination, field strength and others, on the Earth's surface. One of our actions in the project is preparation of the documentations of the geomagnetic field and its fluctuations for education and outreach. Especially in Japan, there are poor treatments in the education during elementary and high schools, and the expository writing of the geomagnetic field and concerned articles are also scarce. Moreover, we provide the movie files and stereoscopic visions for the user experiences of the 3D images.

  18. The Vector Matching Method in Geomagnetic Aiding Navigation.

    PubMed

    Song, Zhongguo; Zhang, Jinsheng; Zhu, Wenqi; Xi, Xiaoli

    2016-01-01

    In this paper, a geomagnetic matching navigation method that utilizes the geomagnetic vector is developed, which can greatly improve the matching probability and positioning precision, even when the geomagnetic entropy information in the matching region is small or the geomagnetic contour line's variety is obscure. The vector iterative closest contour point (VICCP) algorithm that is proposed here has better adaptability with the positioning error characteristics of the inertial navigation system (INS), where the rigid transformation in ordinary ICCP is replaced with affine transformation. In a subsequent step, a geomagnetic vector information fusion algorithm based on Bayesian statistical analysis is introduced into VICCP to improve matching performance further. Simulations based on the actual geomagnetic reference map have been performed for the validation of the proposed algorithm. PMID:27447645

  19. Interplanetary magnetic sector polarity inferred from polar geomagnetic field observations

    NASA Technical Reports Server (NTRS)

    Friis-Christensen, E.; Lassen, K.; Wilcox, J. M.; Gonzalez, W.; Colburn, D. S.

    1971-01-01

    In order to infer the interplanetary sector polarity from polar geomagnetic field diurnal variations, measurements were carried out at Godhavn and Thule (Denmark) Geomagnetic Observatories. The inferred interplanetary sector polarity was compared with the polarity observed at the same time by Explorer 33 and 35 magnetometers. It is shown that the polarity (toward or away from the sun) of the interplanetary magnetic field can be reliably inferred from observations of the polar cap geomagnetic fields.

  20. Geomagnetic excursions date early hominid migration to China

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-09-01

    Global-scale geomagnetic reversals, which are periods when the direction of Earth's magnetic field flips, leave imprints in magnetic minerals present in sediments. But so do smaller-scale, even local, changes in Earth's magnetic field direction. Paleomagnetists believe that the smaller-scale events represent “failed reversals” and refer to them as “geomagnetic excursions.” Scientists use geomagnetic excursions in sedimentary basins as markers to tie together events of Earth's history across the globe.

  1. Geomagnetic field models incorporating physical constraints on the secular variation

    NASA Technical Reports Server (NTRS)

    Constable, Catherine; Parker, Robert L.

    1993-01-01

    This proposal has been concerned with methods for constructing geomagnetic field models that incorporate physical constraints on the secular variation. The principle goal that has been accomplished is the development of flexible algorithms designed to test whether the frozen flux approximation is adequate to describe the available geomagnetic data and their secular variation throughout this century. These have been applied to geomagnetic data from both the early and middle part of this century and convincingly demonstrate that there is no need to invoke violations of the frozen flux hypothesis in order to satisfy the available geomagnetic data.

  2. Comparative climatological study of large-scale traveling ionospheric disturbances over North America and China in 2011-2012

    NASA Astrophysics Data System (ADS)

    Ding, Feng; Ning, Baiqi; Wan, Weixing; Zhao, Biqiang; Xiong, Bo

    This paper describes a comparative study of the climatology of large-scale traveling ionospheric disturbances (LSTIDs) over North America and China based on observations obtained in 2011-2012 using two GPS networks characterized by dense regional coverage. We identified a total of 390 LSTIDs in China and 363 events in North America. These can be categorized into three types, namely south-, north-, and westward-propagating LSTIDs. The southward-moving LSTIDs over North America show similar diurnal and seasonal variations to those of geomagnetic disturbances, but the southward LSTIDs over China do not show such variations. The occurrence of southward-propagating LSTIDs over China increases at ~1-2 hours after the time of geomagnetic activity maximum; this increase lasts several hours until the geomagnetic activity minimum, which happens during the local evening. The southward-moving LSTIDs over North America show a weak semiannual variation, with two major peaks in March and October, while the southward-propagating LSTIDs over China show a major peak in January. Northward-propagating LSTIDs occur much less frequently than their southward-moving counterparts, and they are mainly observed in China. They mostly occur during geomagnetic activity maximum, indicating a possible relation with the degree of geomagnetic activity. Westward-traveling LSTIDs are seen in both regions during local sunrise and may be excited by the moving solar terminator. No relationship was found between these latter LSTIDs and the geomagnetic disturbances. The propagation direction of westward-moving events changed from northwestward during winter solstice to southwestward at summer solstice. This is consistent with the seasonal orientation of the solar terminator.

  3. Ionospheric Irregularities at High Latitudes During Geomagnetic Storms and Substorms: Simultaneous Observations of Magnetic Field Perturbations and GPS Scintillations

    NASA Astrophysics Data System (ADS)

    Kim, H.; Deshpande, K.; Clauer, C. R.; Bust, G. S.; Crowley, G.; Humphreys, T. E.; Kim, L.; Lessard, M.; Weatherwax, A. T.; Zachariah, T. P.

    2012-12-01

    Plasma instability in the ionosphere is often observed as disturbance and distortion of the amplitude and phase of radio signals, which are known as ionospheric scintillations. High-latitude ionospheric plasma, closely connected to solar wind and magnetospheric dynamics, produce very dynamic and short-lived GPS scintillations, making it challenging to characterize them. This study reports simultaneous observations of geomagnetic pulsations and GPS signal scintillations during geomagnetic storms and substorms using a newly designed Autonomous Adaptive Low-Power Instrument Platform (AAL-PIP) installed at the South Pole. A statistical investigation of the AAL-PIP data recorded from January through May 2012 is presented to study local time distribution of scintillation events and a correlation between GPS scintillation and magnetic field perturbations. This report discusses a possible connection between magnetic field perturbations associated with the ionospheric currents and the creation of plasma instability by examining relative contribution of storm/substorm activity to ionospheric irregularities.

  4. GPS Observation of Fast-moving Continent-size Traveling TEC Pulsations at the Start of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Valladares, C. E.; Doherty, P. H.

    2014-12-01

    Using network of GPS receiver stations in North and South America, we have recently observed fast-moving continent-size traveling plasma disturbances in the mapped total electron content (TEC) data. These space plasma disturbances occurred at the beginning of geomagnetic storms, immediately after the storm's suddent commencement (SSC) and prior to the appearance of large-scale traveling ionospheric disturbances (LSTIDs) from the auroral regions. More specifically, these supersize TEC perturbations were observed when the IMF Bz was oscillating between northward and southward directions. They were found to propagate zonally westward with a propagation speed of 2-3 km/s, if projected onto an ionospheric-equivalent altitude of 350 km. Based on their general characteristics and comparison with ground-based ionosonde data, we interpret these TEC pulsations as ion drift waves in the magnetosphere/plasmasphere that propagate azimuthally inside the GPS orbit.

  5. Comparison between the effect of two geomagnetic storms with the same seasonal and daily characteristics and different intensity on the European ionosphere.

    NASA Astrophysics Data System (ADS)

    Rodriguez-Bouza, Marta; Herraiz, Miguel; Rodríguez-Caderot, Gracía; Paparini, Claudia; Otero, Xurxo; Radicella, Sandro M.

    2016-04-01

    This work presents an analysis of the ionospheric disturbance caused by two geomagnetic storms occurred on the same day, 17th March, but one in 2013 and other in 2015. The greatest intensity of both storms occurs after sunset when geomagnetic indexes (Dst index, Kp and Ap) reached the peak values. Both geomagnetic storms can be classified as intense according to the Dst index criteria. The storm of March 17, 2015, ("St Patricḱs storm"), can be considered even "severe" because the Dst index dropped off -200nT. The solar origins of both geomagnetic storms were magnetic filament eruptions followed by Coronal Mass Ejections, CME. The ionospheric behavior has been studied through the total electron content, TEC. This parameter is obtained from RINEX files processed using the calibration technique developed by Prof. Luigi Ciraolo. RINEX files from selected GNSS stations on Europe belonging to International GPS Service, IGS, and EUREF Permanent Network, have been used. The calibration technique assumes the ionospheric thin shell model to obtain vertical total electron content (vTEC) from slant total electron content (sTEC) at the Ionospheric Pierce Point. The data were obtained in periods of the geomagnetic storms and during quite days surrounding the storms days, at 1 minute sampling. The behavior of the ionosphere during the two geomagnetic storms was similar. In both cases, a positive ionospheric storm, defined as an increase on the TEC, occurred during the main phase of the geomagnetic storms on 17th of March. These increases were followed by a negative ionospheric storm, a decreasing of TEC, in the recuperation phase. However, in the event of 2015, the positive ionospheric storm of the main phase had more intensity but the same duration than that of 2013 and for the negative ionospheric storm both, intensity and duration, were largest in 2015 than in 2013.

  6. A Superposed Epoch Analysis of Geomagnetic Storms over a Solar Cycle: Geomagnetic and Solar Wind Data, Radar Backscatter & Auroral Imagery

    NASA Astrophysics Data System (ADS)

    Hutchinson, J. A.; Wright, D. M.; Milan, S. E.; Grocott, A.

    2010-12-01

    Geomagnetic storms - episodes of intense solar wind-magnetosphere coupling usually associated with extreme conditions in the solar wind such as coronal mass ejections (CMEs) or co-rotating interaction regions (CIRs) - cause large global disturbances in the Earth’s magnetosphere. During such storms, large amounts of energy are deposited in the magnetotail and inner magnetosphere, producing an enhanced ring current and energising plasma to relativistic levels by as yet unknown excitation mechanisms. By exploiting data from the Advanced Composition Explorer (ACE) spacecraft in conjunction with space- and ground-based measurements of geospace over the last solar cycle, a database of geomagnetic storms has been compiled and analysed. Here we present some statistical findings from a superposed epoch analysis of 143 events identified from the global SYM-H index. We find that the duration of the main phase of storms decreases for increasing storm size, as defined by the maximum negative excursion of SYM-H, contrary to the results of previous studies. We also discuss a comparison of CME and CIR driven storms in terms of storm size, phase duration and evolution, and the associated solar wind-magnetosphere coupling. Initial work has successfully identified characteristic radar backscatter observed by the Super Dual Auoral Radar Network (SuperDARN) and, in particular, the new lower-latitude StormDARN radar network during these storm-time conditions. Here we present early findings of a superposed epoch analysis of auroral imagery from the IMAGE spacecraft and ionospheric convection maps from the SuperDARN radar network. This work further illustrates the storm-time coupling between the solar wind and magnetosphere, and develops the relationship between auroral oval radius and the evolution of the storm-time SYM-H index first reported by Milan et al., (2009). Once completed, this will be the most complete superposed epoch analyses of storms to date, combining multiple datasets

  7. 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.

  8. Space-time structure of the 2003 geomagnetic jerk at Mid-Eastern Asia

    NASA Astrophysics Data System (ADS)

    Ou, Jiaming; Du, Aimin; Xu, Wenyao; Yang, Dongmei

    2015-04-01

    . Reference 1. Mandea, M., E. Bellanger, and J. L. Le Mouël (2000), A geomagnetic jerk for the end of the 20th century? Earth Planet. Sci. Lett., 183, 369-373. 2. Olsen, N. and M. Mandea (2007), Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk. Earth Planet. Sci. Lett., 255, 94-105. 3. Stewart, D. N. and K. A. Whaler (1992), Geomagnetic disturbance fields: an analysis of observatory monthly means. Geophys. J. Int., 108, 215-223. 4. Wardinski, I., R. Holme, S. Asari, and M. Mandea (2008), The 2003 geomagnetic jerk and its relation to the core surface flows. Earth Planet. Sci. Lett., 267, 468-481.

  9. Behavior of high-latitude irregularities during geomagnetic disturbances. Environmental research papers

    SciTech Connect

    Houminer, Z.; Aarons, J.

    1980-06-24

    Scintillation observations of VHF and UHF transmissions from geostationary satellites at Goose Bay have been used to study the average characteristics of the high latitude irregularity region. The paper describes the average time development and mean diurnal pattern of irregularities during 58 magnetic storms in 1971-1976. The diurnal variation at Goose Bay shows two peaks of scintillation activity. One peak occurs during the afternoon hours, while the second occurs during the night. The average diurnal pattern is independent of type of storm. diurnal and seasonal effects appear only in the first day of storm commencement and not in the following days which show a very similar diurnal picture. (Author)

  10. Statistical Maps of Geomagnetic Disturbance and Climatological Validation of Geospace Models

    NASA Astrophysics Data System (ADS)

    Rigler, E. J.; Wiltberger, M. J.; Gannon, J. L.; Love, J. J.

    2012-12-01

    Considerable recent effort has gone into event-based validation of global geospace models using ground magnetometer data. Less attention has been paid to the statistical characterization and comparison of model output and real measurements. We attempt to ascertain the climatological similarity of model output with observations by comparing not just the means and variances of magnetic field fluctuations, but their linear dependencies as functions of local time. Near-equatorial ground magnetometers exhibit substantial correlation with each other. Given a complete time series of observations at all local times, it is straight-forward to construct a variance-covariance matrix that describes the 2nd statistical moment of each observatory's data, as well as any linear relationships between data obtained from different local times. Observations are not available at all local times for all time periods because magnetic observatories are sparsely distributed in longitude. However, each observatory does pass through every local time once per day, which allows a covariance matrix to be built up incrementally. We do this using statistical imputation: starting with a best initial guess for the covariance matrix, "missing" observations are replaced with the most-likely value obtained by regressing on available observations; the covariance matrix is updated; and the process is repeated until convergence is achieved (this is guaranteed by the well-known expectation maximization (EM) algorithm). Finally, a comparable covariance matrix is constructed from the geospace model output, and the two multivariate distributions are compared.

  11. Auroral electrojets during severely disturbed geomagnetic condition on 24 August 2005

    NASA Astrophysics Data System (ADS)

    Singh, Anand K.; Sinha, A. K.; Saini, S.; Rawat, Rahul

    2015-03-01

    Very intense and highly dynamic eastward and westward currents flowing in the auroral ionosphere are traditionally monitored by the auroral electrojet indices - AUand AL , respectively. In this study we show that on occasions of intense magnetic activity, entire auroral oval could be dominated by the westward flowing currents, which lead to depression not only in AL index but also in supposedly positive AU index. During negative AU intervals, there could be up to ∼ 20 % underestimation of the total maximum intensity of the auroral electrojet represented by AEindex (defined as AU - AL). A detailed investigation of a well-studied extremely intense event of 24 August 2005 has been carried out. Global prevalence of the westward auroral electrojet was clearly observed at the auroral latitudes during the unusually intense substorm (AL ∼ - 4000 nT) on the day. Moreover, along the noon meridian westward electrojet appeared in the auroral region whereas eastward electrojet shifted towards lower latitudes. This paper emphasizes that intense substorms are represented better by AL index than AE index.

  12. Geomagnetic imprint of the Persani volcanism

    NASA Astrophysics Data System (ADS)

    Besutiu, Lucian; Seghedi, Ioan; Zlagnean, Luminita; Atanasiu, Ligia; Popa, Razvan-Gabriel; Pomeran, Mihai; Visan, Madalina

    2016-04-01

    The Persani small volume volcanism is located in the SE corner of the Transylvanian Depression, at the north-western edge of the intra-mountainous Brasov basin. It represents the south-easternmost segment of the Neogene-Quaternary volcanic chain of the East Carpathians. The alkaline basalt monogenetic volcanic field is partly coeval with the high-K calc-alkaline magmatism south of Harghita Mountains (1-1.6 Ma). Its eruptions post-dated the calc-alkaline volcanism in the Harghita Mountains (5.3-1.6 Ma), but pre-dated the high-K calc-alkaline emissions of Ciomadul volcano (1.0-0.03 Ma). The major volcanic forms have been mapped in previous geological surveys. Still, due to the small size of the volcanoes and large extent of tephra deposits and recent sediments, the location of some vents or other volcanic structures has been incompletely revealed. To overcome this problem, the area was subject to several near-surface geophysical investigations, including paleomagnetic research. However, due to their large-scale features, the previous geophysical surveys proved to be an inappropriate approach to the volcanological issues. Therefore, during the summers of 2014 and 2015, based on the high magnetic contrast between the volcanic rocks and the hosting sedimentary formations, a detailed ground geomagnetic survey has been designed and conducted, within central Persani volcanism area, in order to outline the presence of volcanic structures hidden beneath the overlying deposits. Additionally, information on the rock magnetic properties was also targeted by sampling and analysing several outcrops in the area. Based on the acquired data, a detailed total intensity scalar geomagnetic anomaly map was constructed by using the recent IGRF12 model. The revealed pattern of the geomagnetic field proved to be fully consistent with the direction of magnetisation previously determined on rock samples. In order to enhance the signal/noise ratio, the results were further processed by

  13. Analysis of geomagnetic secular variation during 1980-1985 and 1985- 1990, and geomagnetic models proposed for the 1991 revision of the International Geomagnetic Reference Field

    USGS Publications Warehouse

    Peddie, N.W.

    1992-01-01

    The secular variation of the main geomagnetic field during the periods 1980-1985 and 1985-1990 was analyzed in terms of spherical harmonics up to the eighth degree and order. Data from worldwide magnetic observatories and the Navy's Project MAGNET aerial surveys were used. The resulting pair of secular-variation models was used to update the Definitive Geomagnetic Reference Field (DGRF) model for 1980, resulting in new mainfield models for 1985.0 and 1990.0. These, along with the secular-variation model for 1985-1990, were proposed for the 1991 revision of the International Geomagnetic Reference Field (IGRF). -Author

  14. On Chu's disturbance energy

    NASA Astrophysics Data System (ADS)

    Joseph George, K.; Sujith, R. I.

    2011-10-01

    Chu [On the energy transfer to small disturbances in fluid flow (part I), Acta Mechanica 1 (1965) 215-234] proposed a positive definite energy norm for characterizing the level of fluctuation in a disturbance. In the absence of heat transfer at the boundaries, work done by boundary or body forces, heat and material sources of energy, this norm is a monotone, non-increasing function of time. In this paper, we show that Chu's disturbance energy defines an inner product, with respect to which the conservation equations of fluid motion linearized about a uniform base flow are self-adjoint. This ensures that the eigenvectors of the linearized operator are orthogonal to each other, and the property that the energy norm is a non-increasing function of time in the absence of physical sources of energy follows as an immediate consequence. Examples from numerical simulations of Euler equations are presented to highlight the importance of choosing an energy norm that is consistent with the underlying physics. We demonstrate that the disturbance energy as measured by Chu's norm does not exhibit spurious transient growth in the absence of physical sources of energy and hence is suitable for analyzing thermoacoustic instability.

  15. Halo Coronal Mass Ejections and Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2009-01-01

    In this letter, I show that the discrepancies in the geoeffectiveness of halo coronal mass ejections (CMEs) reported in the literature arise due to the varied definitions of halo CMEs used by different authors. In particular, I show that the low geoeffectiveness rate is a direct consequence of including partial halo CMEs. The geoeffectiveness of partial halo CMEs is lower because they are of low speed and likely to make a glancing impact on Earth. Key words: Coronal mass ejections, geomagnetic storms, geoeffectiveness, halo CMEs.

  16. Geomagnetically Induced Currents: Progress and Issues

    NASA Astrophysics Data System (ADS)

    Thomson, Alan

    2010-05-01

    Geomagnetically induced currents (GIC) are a hazard to conducting networks such as high-voltage power and pipeline grids. GIC have been known for decades to affect power systems at higher latitudes (e.g. Europe and North America), although more recently GIC have also been found to affect power networks at middle and lower latitudes. Mitigating the effects of GIC remains an issue for the power and pipeline industries and for governments concerned with the societal and economic implications. To understand, e.g. to model and predict, GIC in conducting grids needs expertise drawn from electrical engineering, geophysics and space weather science - a truly multi-disciplinary undertaking. In terms of geophysics and space physics, issues such as Earth structure (e.g. 3D versus 1D mantle and lithospheric conductivity structure), ocean/continent conductivity contrasts, ionospheric current systems and their variability and Sun-Earth magnetic interactions are all relevant. The start of solar cycle 24 provides an opportune time to consider the status of GIC research and to assess what new studies are required in geophysical modelling and in hazard analysis. What do we need to improve on to better specify/predict GIC flowing in power grids, from ‘up-stream' observations of coronal mass ejections through to geomagnetic field measurements made during magnetic storms? In this invited review we will consider aspects of a) Measurement: how do we measure GIC in grids; b) Analysis: how do measured GIC relate to geophysical and space physics data; c) Modelling: what methods exist for modelling GIC, again in relation to other data, and how accurate are models; and d) Prediction: how predictable are GIC and what are the implications for, e.g., the power industry and national governments. We will review the more recent developments in GIC and related geomagnetism and space weather science. We will outline what issues are widely believed to now be understood and what issues remain to be

  17. Geomagnetic field modeling by optimal recursive filtering

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Five individual 5 year mini-batch geomagnetic models were generated and two computer programs were developed to process the models. The first program computes statistics (mean sigma, weighted sigma) on the changes in the first derivatives (linear terms) of the spherical harmonic coefficients between mini-batches. The program ran successfully. The statistics are intended for use in computing the state noise matrix required in the information filter. The second program is the information filter. Most subroutines used in the filter were tested, but the coefficient statistics must be analyzed before the filter is run.

  18. Advanced Theory of Deep Geomagnetic Sounding

    NASA Astrophysics Data System (ADS)

    Chave, Alan D.

    Advanced Theory of Deep Geomagnetic Sounding is a specialized treatise that covers recent work, mostly from the Soviet Union, on the theory, analysis, and interpretation of natural source electromagnetic induction processes in complex geological structures, with an emphasis on subsurface conductive anomalies. The scope of the book is limited, as suggested by the title, and the authors stress the application of electromagnetic principles to the study of regional geology and deep earth structure rather than surface exploration. The book is clearly aimed at the practicing specialist rather than the graduate student attempting to learn about the broader field of electromagnetic geophysics.

  19. Geomagnetic field behaviour preceding a Superchron: new evidence for a weak Devonian geomagnetic field

    NASA Astrophysics Data System (ADS)

    Hawkins, L.; Anwar, T.; Scherbakova, V.; Biggin, A. J.; Kravchinsky, V. A.; Shatsillo, A.; Holt, J.; Pavlov, V.

    2015-12-01

    The ~50 million year transition from the peak in reversal frequency in the Middle Jurassic (~170Ma), associated with a weak geomagnetic field, to the stable and apparently strong field during the Cretaceous Normal Superchron (84-121Ma), represents a dramatic change in time-averaged geomagnetic field behaviour during the Mesozoic Era. New evidence from Siberian samples suggests there is a similar transition in geomagnetic field behaviour during the Palaeozoic, with a weak geomagnetic field in the Upper Devonian preceding the Permo-Carboniferous Superchron (262-318Ma). Both sites, the Viluy Traps and the Zharovsk complex of the Patom Margin, have seemingly reliable, published palaeomagnetic directions and new age constraints, 364.4 ± 1.7Ma (40Ar/39A) 371-377Ma (U-Pb) respectively. The samples were measured using the Thermal Thellier-Coe protocol with partial thermo-remanent magnetisation (pTRM) and tail checks and the Microwave Thellier-IZZI protocol with pTRM checks. Accepted Arai plots show positive pTRM checks, a clear relation between distinct primary directional and palaeointensity components and little to no zig-zagging. Three distinct magneto-mineralogical types were identified from SEM and rock magnetic techniques; low Ti- and intermediate Ti- titanomagnetite and possible maghemite, with mineral type affecting the success rate of samples but resulting in no significant variation in palaeointensity results. The Arai plots also commonly have a distinct two-slope concave-up shape, although non-heating, pseudo-Thellier experiments have supported this resulting from a strong overprint component rather than alteration or multi-domain effects. Results from these experiments give low site mean values between 2.3-29.9μT (Virtual Dipole Moments 4-50.6 ZAm2). The apparently periodic (~180 million years) transitions in geomagnetic field behaviour may indicate the influence of mantle convection changing heat flow across the Core Mantle Boundary.

  20. The use of geomagnetic field models in magnetic surveys

    NASA Technical Reports Server (NTRS)

    Regan, R. D.; Gain, J. C.

    1974-01-01

    The importance of global geomagnetic field models for the reduction of magnetic surveys is discussed. It is demonstrated that a numerical model with adequate secular variation correction, provides a suitable representation of the regional field. The limitations of the presently available models are reported, with emphasis on the International Geomagnetic Reference Field.

  1. A primary research on marine magnetic disturbance using GPS precise point positioning

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Luo, X.

    2014-12-01

    Marine magnetic survey is an important mean of geophysical exploration. The magnetic disturbance magnitude, the start and end time, and perfecting magnetic disturbance model are important for magnetic survey. In this paper, on the basis of that dual-frequency GNSS is able to get the ionospheric total electron content,reflect the nature of the magnetic disturbance characteristics,Etc. the study of magnetic disturbance correction in marine magnetism measurements using dual-frequency GNSS is carried out. Through quality controlled by the dual-frequency GNSS phase observations, ionospheric total electron content solved by static and dynamic at slant direction. Comparing the solving with geomagnetic observatories and marine magnetic measurements, the solution showed that there is relatively strong correlation between ionospheric total electron content and marine magnetic surveys. This fact helps to perfect magnetic interference correction model and improve the accuracy of magnetic measurement. Also it is a good foundation for the application of GNSS to carry out new areas.

  2. The 1859 Solar-Terrestrial Disturbance And the Current Limits of Extreme Space Weather Activity

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.; Svalgaard, L.

    2004-10-01

    It is generally appreciated that the September 1859 solar-terrestrial disturbance, the first recognized space weather event, was exceptionally large. How large and how exceptional? To answer these questions, we compiled rank order lists of the various measures of solar-induced disturbance for events from 1859 to the present. The parameters considered included: magnetic crochet amplitude, solar energetic proton fluence (McCracken et al., 2001a), Sun-Earth disturbance transit time, geomagnetic storm intensity, and low-latitude auroral extent. While the 1859 event has close rivals or superiors in each of the above categories of space weather activity, it is the only documented event of the last ˜150 years that appears at or near the top of all of the lists. Taken together, the top-ranking events in each of the disturbance categories comprise a set of benchmarks for extreme space weather activity.

  3. Relationship between Dst and solar wind conditions during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Olusesan, Bakare; Chukwuma, Victor

    2012-07-01

    A study of 224 geomagnetic storms of which 83 intense and 141 moderate storms during 1996-2006 has been carried out to investigate the relationship between Dst and solar wind plasma parameters during geomagnetic storms. The geomagnetic storms are primarily associated with two classes of drivers: the magnetic cloud and complex ejecta. Out of 83 intense geomagnetic storms studied, it was found that magnetic cloud were drivers in 43 geomagnetic storm (~ 51.8%) while complex ejecta were responsible for 40 geomagnetic storms (~ 48.2%). The correlation between Dst and B; and between Dst and Bs was 0.76 and 0.90, respectively for geomagnetic storms resulting from magnetic clouds. The correlation between Dst and B; and between Dst and Bs was 0.71 and 0.64, respectively for geomagnetic storms resulting from complex ejecta. Furthermore, it was shown that the correlation between the Dst and V for magnetic cloud and complex ejecta was 0.58 and 0.57, respectively. It was observed that the correlation between Dst and VBs for magnetic cloud and complex ejecta were 0.77 and 0.71, respectively. Further study of 141 moderate geomagnetic storms shows that the magnetic cloud comprised nearly (33.3%) of the storms while the complex ejecta comprised of about 66.7%. The result shows that the number of magnetic cloud occurrence is nearly double that of complex ejecta. The correlation between Dst and B; and between Dst and Bs was 0.38 and 0.64, respectively for geomagnetic storms resulting from magnetic clouds. The correlation between Dst and B; and between Dst and Bs was 0.43 and 0.53, respectively for geomagnetic storms resulting from complex ejecta. In addition, it was shown that the relationship between the Dst and V for magnetic cloud and complex ejecta was 0.15 and 0.11, respectively. It was observed that the relationship between Dst and VBs for magnetic cloud and complex ejecta were 0.64 and 0.59 respectively. Finally, the present results suggest that though both classes of drivers

  4. Atmospheric helium and geomagnetic field reversals.

    NASA Technical Reports Server (NTRS)

    Sheldon, W. R.; Kern, J. W.

    1972-01-01

    The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

  5. Solar Wind Charge Exchange During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  6. 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.

  7. Survey Data for Geomagnetic Field Modelling

    NASA Technical Reports Server (NTRS)

    Barraclough, D. R.; Macmillan, S.

    1992-01-01

    The survey data discussed here are based on observations made relatively recently at points on land. A special subset of land survey data consists of those made at specially designated sites known as repeat stations. This class of data will be discussed in another part of this document (Barton, 1991b), so only the briefest of references will be made to repeat stations here. This discussion of 'ordinary' land survey data begins with a description of the spatial and temporal distributions of available survey data based on observations made since 1900. (The reason for this rather arbitrary choice of cut-off date is that this was the value used in the production of the computer file of magnetic survey data (land, sea, air, satellite, rocket) that is the primary source of data for geomagnetic main-field modeling). This is followed by a description of the various types of error to which these survey data are, or may be, subject and a discussion of the likely effects of such errors on field models produced from the data. Finally, there is a short section on the availability of geomagnetic survey data, which also describes how the data files are maintained.

  8. Waveguide disturbance detection method

    DOEpatents

    Korneev, Valeri A.; Nihei, Kurt T.; Myer, Larry R.

    2000-01-01

    A method for detection of a disturbance in a waveguide comprising transmitting a wavefield having symmetric and antisymmetric components from a horizontally and/or vertically polarized source and/or pressure source disposed symmetrically with respect to the longitudinal central axis of the waveguide at one end of the waveguide, recording the horizontal and/or vertical component or a pressure of the wavefield with a vertical array of receivers disposed at the opposite end of the waveguide, separating the wavenumber transform of the wavefield into the symmetric and antisymmetric components, integrating the symmetric and antisymmetric components over a broad frequency range, and comparing the magnitude of the symmetric components and the antisymmetric components to an expected magnitude for the symmetric components and the antisymmetric components for a waveguide of uniform thickness and properties thereby determining whether or not a disturbance is present inside the waveguide.

  9. 300 Area Disturbance Report

    SciTech Connect

    LL Hale; MK Wright; NA Cadoret

    1999-01-07

    The objective of this study was to define areas of previous disturbance in the 300 Area of the U.S. Department of Energy (DOE) Hanford Site to eliminate these areas from the cultural resource review process, reduce cultural resource monitoring costs, and allow cultural resource specialists to focus on areas where subsurface disturbance is minimal or nonexistent. Research into available sources suggests that impacts from excavations have been significant wherever the following construction activities have occurred: building basements and pits, waste ponds, burial grounds, trenches, installation of subsurface pipelines, power poles, water hydrants, and well construction. Beyond the areas just mentioned, substrates in the' 300 Area consist of a complex, multidimen- sional mosaic composed of undisturbed stratigraphy, backfill, and disturbed sediments; Four Geographic Information System (GIS) maps were created to display known areas of disturbance in the 300 Area. These maps contain information gleaned from a variety of sources, but the primary sources include the Hanford GIS database system, engineer drawings, and historic maps. In addition to these maps, several assumptions can be made about areas of disturbance in the 300 Area as a result of this study: o o Buried pipelines are not always located where they are mapped. As a result, cultural resource monitors or specialists should not depend on maps depicting subsurface pipelines for accurate locations of previous disturbance. Temporary roads built in the early 1940s were placed on layers of sand and gravel 8 to 12 in. thick. Given this information, it is likely that substrates beneath these early roads are only minimally disturbed. Building foundations ranged from concrete slabs no more than 6 to 8 in. thick to deeply excavated pits and basements. Buildings constructed with slab foundations are more numerous than may be expected, and minimally disturbed substrates may be expected in these locations. Historic black

  10. Atmospheric Disturbance Environment Definition

    NASA Technical Reports Server (NTRS)

    Tank, William G.

    1994-01-01

    Traditionally, the application of atmospheric disturbance data to airplane design problems has been the domain of the structures engineer. The primary concern in this case is the design of structural components sufficient to handle transient loads induced by the most severe atmospheric "gusts" that might be encountered. The concern has resulted in a considerable body of high altitude gust acceleration data obtained with VGH recorders (airplane velocity, V, vertical acceleration, G, altitude, H) on high-flying airplanes like the U-2 (Ehernberger and Love, 1975). However, the propulsion system designer is less concerned with the accelerations of the airplane than he is with the airflow entering the system's inlet. When the airplane encounters atmospheric turbulence it responds with transient fluctuations in pitch, yaw, and roll angles. These transients, together with fluctuations in the free-stream temperature and pressure will disrupt the total pressure, temperature, Mach number and angularity of the inlet flow. For the mixed compression inlet, the result is a disturbed throat Mach number and/or shock position, and in extreme cases an inlet unstart can occur (cf. Section 2.1). Interest in the effects of inlet unstart on the vehicle dynamics of large, supersonic airplanes is not new. Results published by NASA in 1962 of wind tunnel studies of the problem were used in support of the United States Supersonic Transport program (SST) (White, at aI, 1963). Such studies continued into the late 1970's. However, in spite of such interest, there never was developed an atmospheric disturbance database for inlet unstart analysis to compare with that available for the structures load analysis. Missing were data for the free-stream temperature and pressure disturbances that also contribute to the unStart problem.

  11. Response of the thermosphere and ionosphere to geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Fuller-Rowell, T. J.; Codrescu, M. V.; Moffett, R. J.; Quegan, S.

    1994-01-01

    Four numerical simulations have been performed, at equinox, using a coupled thermosphere-ionosphere model, to illustrate the response of the upper atmosphere to geomagnetic storms. The storms are characterized by an increase in magnetospheric energy input at high latitude for a 12-hour period; each storm commences at a different universal time (UT). The initial response at high latitude is that Joule heating raises the temperature of the upper thermosphere and ion drag drives high-velocity neutral winds. The heat source drives a global wind surge, from both polar regions, which propagates to low latitudes and into the opposite hemisphere. The surge has the character of a large-scale gravity wave with a phase speed of about 600 m/s. Behind the surge a global circulation of magnitude 100 m/s is established at middle latitudes, indicating that the wave and the onset of global circulation are manifestations of the same phenomena. A dominant feature of the response is the penetration of the surge into the opposite hemisphere where it drives poleward winds for a few hours. The global wind surge has a preference for the night sector and for the longitude of the magnetic pole and therefore depends on the UT start time of the storm. A second phase of the meridional circulation develops after the wave interaction but is also restricted, in this case by the buildup of zonal winds via the Coriolis interaction. Conservation of angular momentum may limit the buildup of zonal wind in extreme cases. The divergent wind field drives upwelling and composition change on both height and pressure surfaces. The composition bulge responds to both the background and the storm-induced horizontal winds; it does not simply rotate with Earth. During the storm the disturbance wind modulates the location of the bulge; during the recovery the background winds induce a diurnal variation in its position. Equatorward winds in sunlight produce positive ionospheric changes during the main driving

  12. Ionospheric response to the sustained high geomagnetic activity during the March 1989 great storm

    SciTech Connect

    Sojka, J.J.; Schunk, R.W.; Denig, W.F.

    1994-11-01

    A simulation was conducted to model the high-latitude ionospheric response to the sustained level of high geomagnetic activity for the great magnetic storm period of March, 13-14, 1989. The geomagnetic and solar activity indices and the DMSP F8 and F9 satellite data for particle precipitation and high-latitude convection were used as inputs to a time-dependent ionospheric model (TDIM). The results of the TDIM were compared to both DMSP plasma density data and ground-based total electron content (TEC) measurements for the great storm period as well as with earlier storm observations. The comparisons showed that the overall structure of the high-latitude ionosphere was dominated by an increased convection speed within the polar cap that led to increased ion temperatures. In turn, this enhanced the NO(+) density, raised the atomic-to-molecular ion transition height to over 300 km, decreased N{sub m}F{sub 2}, increased h{sub m}F{sub 2}, and in places either increased n{sub e} at 800 km or slightly decreased it. The morphology of the ionosphere under, these extreme conditions was considerably different than that modeled for less disturbed intervals. These differences included the character of the dayside tongue of ionization that no longer extended deep into the polar cap. Instead, as a result of the ion heating and consequent reduction in N{sub m}F{sub 2}, a large polar hole occupied much of the polar region. This polar hole extended beyond the auroral oval and merged with the night sector midlatitude trough. The limitations associated with the applicability of the TDIM to the geomagnetic conditions present on March 13 and 14 are discussed.

  13. Vehicle Disturbance Test

    NASA Astrophysics Data System (ADS)

    Clapp, Brian

    2001-07-01

    The Vehicle Disturbance Test {VDT} is used to characterize uncompensated environmental disturbances acting upon the HST during normal operation. The VDT is a passive test {not a forced-response test} used to obtain signatures for both externally induced {e.g. SA-3} and internally induced {e.g. NCC and ACS mechanisms} disturbances for comparison with past VDT results. The disturbances observed will be used as the nominal on-orbit disturbances in pointing control simulations until the next VDT is run. The test occurs after release, and most of the VDT can be run during the BEA period. The -V1 sunpoint portion of the VDT occurs after the BEA period is complete. The VDT shall consist of five separate tests that need not occur consecutively. The overall duration of the VDT tests is at least 17 orbits of spacecraft time including {1} at least 1 full orbit at +V3 sunpoint prior to NCS CPL turn-on while performing ACS mechanism motions simulating routine flight operations, {2} at least 5 full orbits at +V3 sunpoint prior to NCS CPL turn-on, {3} at least 1 full orbit at +V3 sunpoint during NCC startup, {4} at least 5 full orbits at +V3 sunpoint while NCC is operating at steady-state, and {5} at least 5 full orbits at -V1 sunpoint with the NCC operating at steady-state. Each test is initiated via SMS execution of stored program macros in the HST flight computer to switch the attitude control law gains to low-bandwidth maneuver gains, command the gyros into low mode, terminate Velocity aberration and parallax {VAP} processing, and modify flight computer diagnostic mnemonics to display the roll component of DVTHEP. The nominal attitude control law configuration will be restored at the end of each test via SMS execution of stored program macros. The stored program command macros are developed specifically for the VDT by the Flight Software and Pointing Control System groups.

  14. Trends of solar-geomagnetic activity, cosmic rays, atmosphere, and climate changes

    NASA Astrophysics Data System (ADS)

    Voronin, N.; Avakyan, S.

    2009-04-01

    result of geomagnetic disturbances. All these fluxes are completely absorbed in the ionosphere and hence do not reach lower atmosphere. Our novel radiooptical trigger mechanism of influence of solar and geomagnetic activity on the formation of weather and climate changes consists of three stages. The first stage is an increase in generation of the microwave radiation which penetrates from the ionosphere to the earth surface. The microwave radiation arises from the transitions between Rydberg states which are exited by the energetic ionospheric electrons. The second stage is a change in the proportion of water vapour to water clusters caused by increased microwave radiation. The third stage is a change of the atmosphere transparency in the absorption bands of water vapour and clusters. The atmosphere transparency determines the fluxes of solar irradiance coming down as well as flux of the thermal radiation coming out from the underlying surface. These fluxes form the basis of the thermal balance and affect the weather and climate characteristics of the lower troposphere. The novel mechanism explains how factors of solar and geomagnetic activities affect atmospheric processes and why the changes observed in long-term trends might result in slowing down of global warming in the nearest future. According to the recent analysis of meteorological data (NASA Goddard Institute for Space Studies, 2008) the rate of global warming in 2008 appears to be slowing in comparison with the last eight years.

  15. Ionospheric, protonospheric and total electron content in quiet geomagnetic conditions and during geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Nosikov, Igor; Klimenko, Maxim; Klimenko, Vladimir

    This report presents the results of studies the ionospheric, plasmaspheric and total electron content during recent minimum of solar activity in quiet geomagnetic condition and for geomagnetic storm on 26 September 2011. A comparison of the calculation results obtained using the GSM TIP model, with observational data of the mid- and high-latitude ionospheric sounding stations, as well as estimation of the plasmaspheric reservoir contribution into the total electron content obtained from GPS TEC measurements, COSMIC radio-occultation experiment and incoherent scatter radars were presented. The particular attention is given to the global distribution of the O+/H+ transition height in order to determine the top and low boundary for ionospheric and protonospheric electron content, respectively. This work was supported by Grant of Russian President №МК-4866.2014.5, №14-05-00578, and Program 22 RAS.

  16. 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

  17. Studies on the Geomagnetic Induction Vectors of China

    NASA Astrophysics Data System (ADS)

    Wang, Qiao; Zhang, Huiqian; Huang, Qinghua

    2016-04-01

    In this study, the geomagnetic data of 16 stations, near 6 years for most, provided by the National Geomagnetic Center of China, were used to study on the geomagnetic induction vectors. The stations cover the whole North China and part of southwestern China, both of which has a complicate geological and tectonic background. This study will not only advance the understanding of regional tectonic variations, but also provide some suggestions on the construction for geomagnetic observation network of earthquake monitoring. The time series of geomagnetic induction vectors were obtained by the robust estimation method, which has been verified and compared with the ordinary least square and the weighted square method. A principle of selecting a specified period's results from the robust estimation method was defined. Then, the results with the period of 640s for all stations were selected by this principle. The long-term trends (more than six months at least) within the time series were extracted by the Fourier harmonic analysis. Consistent phase variations exist for most stations within a similar tectonic background. About one-month period variations in the most stations' results after removing the long-term trends were found. Spectrum analysis for the results and geomagnetic activity index showed that those phenomena may relate to the period of the global geomagnetic activity. A preference azimuth of the geomagnetic induction vectors was found in each station by statistical analysis on the time series. It pointed out the possible relatively high conductivity structures. Exactly, geomagnetic vectors of BJI, JIH, LYH and TAY station, which surround the basin of North China, suggested a relatively higher conductivity layer; that of stations around the Erdos block suggested a complicated structure. Three-dimension inversion by ModEM verifies our results.

  18. Disturbing Behavior Checklists" Technical Manual

    ERIC Educational Resources Information Center

    Algozzine, Bob

    2012-01-01

    Ecological theorists have suggested that "disturbance" may result from an interaction between a child's behavior and reactions to that behavior within ecosystems such as schools. In this context, behavior is viewed as "disturbing" rather than "disturbed" and equal emphasis is given to the child and to individuals with whom the child interacts when…

  19. Interhemispheric propagation and interactions of auroral traveling ionospheric disturbances near the equator

    NASA Astrophysics Data System (ADS)

    Pradipta, Rezy; Valladares, Cesar E.; Carter, Brett A.; Doherty, Patricia H.

    2016-03-01

    We present the results of our GPS total electron content and ionosonde observations of large-scale traveling ionospheric disturbances (LSTIDs) during the 26 September 2011 geomagnetic storm. We analyzed the propagation characteristics of these LSTIDs from the auroral zones all the way to the equatorial region and studied how the auroral LSTIDs from opposite hemispheres interact/interfere near the geomagnetic equator. We found an overall propagation speed of ˜700 m/s for these LSTIDs and that the resultant amplitude of the LSTID interference pattern actually far exceeded the sum of individual amplitudes of the incoming LSTIDs from the immediate vicinity of the interference zone. We suspect that this peculiar intensification of auroral LSTIDs around the geomagnetic equator is facilitated by the significantly higher ceiling/canopy of the ionospheric plasma layer there. Normally, acoustic-gravity waves (AGWs) that leak upward (and thus increase in amplitude) would find a negligible level of plasma density at the topside ionosphere. However, the tip of the equatorial fountain at the geomagnetic equator constitutes a significant amount of plasma at a topside-equivalent altitude. The combination of increased AGW amplitudes and a higher plasma density at such altitude would therefore result in higher-amplitude LSTIDs in this particular region, as demonstrated in our observations and analysis.

  20. Spatial power spectra of the crustal geomagnetic field and core geomagnetic field

    NASA Technical Reports Server (NTRS)

    Mcleod, M. G.; Coleman, P. J., Jr.

    1980-01-01

    Equations providing numerical values of the geomagnetic field spherical harmonic spatial power spectrum as defined by Lowes (1966, 1974) are obtained and this power spectrum is related to various other power spectra. Equations relating the spherical harmonic spatial power spectrum to average great circle power spectra for components of the vector magnetic field in the radial direction, along the great circle track and perpendicular to the first two directions are derived under the assumption that the sources of the field are internal. A statistical model for the crustal and core geomagnetic fields is proposed and used to derive equations for the expected main and crustal spherical harmonic power spectra. The model equations are then compared with observations to determine a scale factor which is then used to obtain an estimate for the core radius and a great circle power spectrum for the field component perpendicular to the great circle and radial directions which are in good agreement with observations. The predicted spherical harmonic power spectrum for the crustal field is found to be consistent with POGO satellite and aircraft data. Other possible models for the crustal and core geomagnetic fields are also briefly considered.

  1. Network of observations on the atmospheric electrical parameters during geomagnetic storm on 5 April 2010

    NASA Astrophysics Data System (ADS)

    Victor, N. Jeni; Manu, S.; Frank-Kamenetsky, A. V.; Panneerselvam, C.; Anil Kumar, C. P.; Elango, P.

    2016-03-01

    The effects of a geomagnetic storm on the variation of the atmospheric electric field over Maitri (70°45'S, 11°44'E), Dome C (75°06'S, 123°20'E), and Vostok (78°27'S, 106°52'E) Antarctic research stations are presented in this paper. For the first time, the paper reports the simultaneous observations of the atmospheric electric field/potential gradient (PG) over the three high-latitude stations at the Southern Hemisphere, and its associated changes due to a substorm phenomenon. PG data obtained from these three stations under fair-weather conditions on 5 April 2010 are analyzed. The duration of geomagnetic disturbance is classified into three intervals, which contains three consecutive substorms based on the magnetic records of the Maitri station. The substorm is directly related to an enhancement of the magnetospheric convective electric field at high latitude, generally controlled by the solar wind parameters. It is found that the variation in the amplitude of PG depends on the magnetic latitude during substorm onset. During the substorm expansion phase, when the convection cell is at overhead, PG is significantly enhanced due to the downward mapping of the ionospheric horizontal electric field. The present observation demonstrated the changes on PG due to the spatial extension of the convection cell from high latitudes up to middle latitudes.

  2. Multipoint Measurements and Global Simulations of the June 23, 2015 Geomagnetic Storm

    NASA Astrophysics Data System (ADS)

    Buzulukova, Natalia; Fok, Mei-Ching; Moore, Thomas E.; Glocer, Alex; Dorelli, John; Sibeck, David; Angelopoulos, Vassilis; Valek, Phil; McComas, David

    2016-04-01

    On 22-23 June 2015 a severe geomagnetic storm occurred with Dst minimum of approximately -200nT. During this extreme event, multipoint observations of magnetospheric dynamics were obtained by a fleet of Geospace spacecraft including MMS, TWINS, Van-Allen Probes and THEMIS. Extensive data coverage allows us to examine the responses of the ring current, radiation belts, ion composition and wave activity during this unusual event, both for the main phase of the storm as well as for the recovery phase. We present results of analysis of satellite data and simulation from a global coupled MHD-ring current model-radiation belt model (BATSRUS-CIMI) to connect multipoint observations from different parts of the magnetosphere. The output of virtual s/c in the global model is calculated and compared with the observations. The analysis helps to identify different magnetospheric domains from multipoint measurements and various magnetospheric boundary motions. We find the model is able to capture the global structure of the magnetosphere. We also explore how the initial disturbance from the solar wind propagates through the magnetosphere causing energization of plasma in the inner magnetosphere and producing severe geomagnetic activity.

  3. EMIC waves observed at geosynchronous orbit under quiet geomagnetic conditions (Kp ≤ 1)

    NASA Astrophysics Data System (ADS)

    Park, J.-S.; Kim, K.-H.; Shiokawa, K.; Lee, D.-H.; Lee, E.; Kwon, H.-J.; Jin, H.; Jee, G.

    2016-02-01

    We statistically study the local time distribution of the helium band electromagnetic ion cyclotron (EMIC) waves observed at geosynchronous orbit when geomagnetic activity was low (Kp ≤ 1). In order to identify the geosynchronous EMIC waves, we use high time resolution magnetic field data acquired from GOES 10, 11, and 12 over a 2 year period from 2007 and 2008 and examine the local time distribution of EMIC wave events. Unlike previous studies, which reported high EMIC wave occurrence in the postnoon sector with a peak around 1500-1600 magnetic local time (MLT) during magnetically disturbed times (i.e., storm and/or substorm), we observed that quiet time EMIC waves mostly occur in a region from morning (˜0600 MLT) to afternoon (˜1600 MLT) with a peak around 1100-1200 MLT. To investigate whether the quiet time EMIC wave occurrence has a causal relationship with magnetospheric convection enhancement or solar wind dynamic pressure variations, we performed a superposed epoch analysis of solar wind parameters (solar wind speed, density, dynamic pressure, and interplanetary magnetic field Bz) and geomagnetic indices (AE and SYM-H). From the superposed epoch analysis we found that solar wind dynamic pressure variation is a more important parameter than AE and SYM-H for quiet time EMIC wave occurrence.

  4. Equatorial All Sky Imager Images from the Seychelles during the March 17th, 2015 geomagnetic storm.

    NASA Astrophysics Data System (ADS)

    Curtis, B.

    2015-12-01

    An all sky imager was installed in the Seychelles earlier this year. The Seychelles islands are located northeast of Madagascar and east of Somalia in the equatorial Indian Ocean. The all sky imager is located on the island of Mahe (4.6667°S, 55.4667°E geographic), (10.55°S, 127.07°E geomagnetic), with filters of 557.7, 620.0, 630.0, 765.0 and 777.4 nm. Images with a 90 second exposure from Seychelles in 777.4nm and 630.0nm from the night before and night of the March 17th geomagnetic storm are discussed in comparison to solar wind measurements at ACE and the disturbance storm time (Dst) index. These images show line-of-sight intensities of photons received dependent on each filters wavelength. A time series of these images sometimes will show the movement of relatively dark areas, or depletions, in each emission. The depletion regions are known to cause scintillation in GPS signals. The direction and speed of movement of these depletions are related to changes observed in the solar wind.

  5. Weakening of the mid-latitude summer nighttime anomaly during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Yamamoto, Mamoru

    2011-04-01

    This brief report presents geomagnetic storm effects on the formation and characteristics of the midlatitude summer nighttime anomaly (MSNA). This anomaly is a phenomenon where the diurnal variation of the plasma density maximizes at night instead of day. Under disturbed geomagnetic conditions, the MSNA is found to have smaller spatial coverage, lower magnitude of the reversed diurnal cycle, and shorter duration of the nighttime enhancement. All these features demonstrate a weakening of the MSNA. In addition, the nighttime maximum tends to occur at earlier local time. These effects can be reasonably understood in the frame of storm-induced equatorward wind and the molecular-rich air it carries along with. For instance, the shrink of the spatial coverage is essentially a dominant effect of the molecular-rich air, which tends to deplete the plasma significantly on the poleward edge of the MSNA region. On the other hand, the smaller magnitude and the shorter duration seem to be mainly caused by the storm-induced equatorward wind. Storm effects presented here add further evidence to the pivot role of effective neutral wind in the formation of MSNA.

  6. Effects of solar and geomagnetic activities on the zonal drift of equatorial plasma bubbles

    NASA Astrophysics Data System (ADS)

    Huang, Chao-Song; Roddy, Patrick A.

    2016-01-01

    Equatorial plasma bubbles are mostly generated in the postsunset sector and then move in the zonal direction. Plasma bubbles can last for several hours and move over hundreds of kilometers (even more than 1000 km). In this study, we use measurements of ion density by the Communication/Navigation Outage Forecasting System satellite to determine the orbit-averaged drift velocity of plasma bubbles. The objective of the study is to identify the dependence of the bubble drift on the solar radio flux and geomagnetic activities. In total, 5463 drift velocities are derived over May 2008 to April 2014, and a statistical analysis is performed. The average pattern of the bubble drift is in good agreement with the zonal drift of the equatorial F region plasma. The zonal drift velocity of plasma bubbles increases with the solar radio flux. However, the increase shows different features at different local times. Geomagnetic activities cause a decrease of the eastward drift velocity of plasma bubbles, equivalent to the occurrence of a westward drift, through disturbance dynamo process. In particular, the decrease of the eastward drift velocity appears to become accelerated when the Dst index is smaller than -60 nT or Kp is larger than 4.

  7. Variability of H-Component of the Geomagnetic Field from Some Equatorial Electrojet Stations

    NASA Astrophysics Data System (ADS)

    Akpaneno, A. F.; Adimula, I. A.

    2015-03-01

    The hourly variation of the H-component of the geomagnetic field from ten MAGDAS observatories along the dip- equator was used to study the variation trend of solar quiet and solar disturbed variation. The variation in H with Sq (H) enhancement in all the ten stations which peak around local noon with steady similar pattern of variation in all the EEJ, are attributed to the enhanced dynamo action at these regions. The variation of Sq (H) was in the range of 20 to 170nT with peaks around 1200-1300LT. Generally, the magnitude of variation on disturbed days are higher due to ionospheric disturbances originating from the external drives such as space weather effects, storms etc. The results also confirmed the presence of counter electrojet, occurring in the morning and evening hours with the maximum amplitude of -25nT recorded during pre-sunset. The data also show that there is a longitudinal variability in the EEJ, with results showing strongest EEJ current in the South American Sector. Pronounced equinoctials maximum which is due to enhanced electron density at equinox was recorded on March and September with the magnitude between 40 to 140nT; a range of about 100nT.

  8. Stochastic resonance in geomagnetic polarity reversals.

    PubMed

    Consolini, Giuseppe; De Michelis, Paola

    2003-02-01

    Among noise-induced cooperative phenomena a peculiar relevance is played by stochastic resonance. In this paper we offer evidence that geomagnetic polarity reversals may be due to a stochastic resonance process. In detail, analyzing the distribution function P(tau) of polarity residence times (chrons), we found the evidence of a stochastic synchronization process, i.e., a series of peaks in the P(tau) at T(n) approximately (2n+1)T(Omega)/2 with n=0,1,...,j and T(omega) approximately 0.1 Myr. This result is discussed in connection with both the typical time scale of Earth's orbit eccentricity variation and the recent results on the typical time scale of climatic long-term variation. PMID:12633403

  9. 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.

  10. Geomagnetic field fluctuations at synchronous orbit. II - Radial diffusion

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.; Webb, D. C.; Arthur, C. W.

    1978-01-01

    Power spectra of geomagnetic-field variations measured at synchronous equatorial altitude (geomagnetic shell parameter about 6.6) in the magnetosphere are used to calculate the time dependence of the radial diffusion coefficient for particles in the radiation belts. The diffusion coefficients calculated are mainly applicable for relativistic electrons. The magnitudes of the derived diffusion coefficients using data only from local day observations are consistent with those reported from analyses of most particle observations and thus are slightly larger than those derived from magnetic sudden commencements. They are consistent with the diffusion coefficients calculated from power spectra of ground-based geomagnetic data measured near L = 4.

  11. Ionosphere TEC disturbances before strong earthquakes: observations, physics, modeling (Invited)

    NASA Astrophysics Data System (ADS)

    Namgaladze, A. A.

    2013-12-01

    The phenomenon of the pre-earthquake ionospheric disturbances is discussed. A number of typical TEC (Total Electron Content) relative disturbances is presented for several recent strong earthquakes occurred in different ionospheric conditions. Stable typical TEC deviations from quiet background state are observed few days before the strong seismic events in the vicinity of the earthquake epicenter and treated as ionospheric earthquake precursors. They don't move away from the source in contrast to the disturbances related with geomagnetic activity. Sunlit ionosphere approach leads to reduction of the disturbances up to their full disappearance, and effects regenerate at night. The TEC disturbances often observed in the magnetically conjugated areas as well. At low latitudes they accompany with equatorial anomaly modifications. The hypothesis about the electromagnetic channel of the pre-earthquake ionospheric disturbances' creation is discussed. The lithosphere and ionosphere are coupled by the vertical external electric currents as a result of ionization of the near-Earth air layer and vertical transport of the charged particles through the atmosphere over the fault. The external electric current densities exceeding the regular fair-weather electric currents by several orders are required to produce stable long-living seismogenic electric fields such as observed by onboard measurements of the 'Intercosmos-Bulgaria 1300' satellite over the seismic active zones. The numerical calculation results using the Upper Atmosphere Model demonstrate the ability of the external electric currents with the densities of 10-8-10-9 A/m2 to produce such electric fields. The sumulations reproduce the basic features of typical pre-earthquake TEC relative disturbances. It is shown that the plasma ExB drift under the action of the seismogenic electric field leads to the changes of the F2 region electron number density and TEC. The upward drift velocity component enhances NmF2 and TEC and

  12. Historical records of the geomagnetic field

    NASA Astrophysics Data System (ADS)

    Arneitz, Patrick; Heilig, Balázs; Vadasz, Gergely; Valach, Fridrich; Dolinský, Peter; Hejda, Pavel; Fabian, Karl; Hammerl, Christa; Leonhardt, Roman

    2014-05-01

    Records of historical direct measurements of the geomagnetic field are invaluable sources to reconstruct temporal variations of the Earth's magnetic field. They provide information about the field evolution back to the late Middle Age. We have investigated such records with focus on Austria and some neighbouring countries. A variety of new sources and source types are examined. These include 19th century land survey and observatory records of the Imperial and Royal "Centralanstalt f. Meteorologie und Erdmagnetismus", which are not included in the existing compilations. Daily measurements at the Imperial and Royal Observatory in Prague have been digitized. The Imperial and Royal Navy carried out observations in the Adriatic Sea during several surveys. Declination values have been collected from famous mining areas in the former Austro-Hungarian Empire. In this connection, a time series for Banska Stiavnica has been compiled. In the meteorological yearbooks of the monastery Kremsmünster regular declination measurements for the first half of the 19th century were registered. Marsigli's observations during military mapping works in 1696 are also included in our collection. Moreover, compass roses on historical maps or declination values marked on compasses, sundials or globes also provide information about ancient field declination. An evaluation of church orientations in Lower Austria and Northern Germany did not support the hypothesis that church naves had been aligned along the East-West direction by means of magnetic compasses. Therefore, this potential source of information must be excluded from our collection. The gathered records are integrated into a database together with corresponding metadata, such as the used measurement instruments and methods. This information allows an assessment of quality and reliability of the historical observations. The combination of compilations of historical measurements with high quality archeo- and paleomagnetic data in a

  13. Recognition of disturbances with specified morphology in time series: Part 2. Spikes on 1-s magnetograms

    NASA Astrophysics Data System (ADS)

    Soloviev, A. A.; Agayan, S. M.; Gvishiani, A. D.; Bogoutdinov, Sh. R.; Chulliat, A.

    2012-05-01

    Preliminary magnetograms contain different types of temporal anthropogenic disturbances: spikes, baseline jumps, drifts, etc. These disturbances should be identified and filtered out during the preprocessing of the preliminary records for the definitive data. As of now, at the geomagnetic observatories, such filtering is carried out manually. Most of the disturbances in the records sampled every second are spikes, which are much more abundant than those on the magnetograms sampled every minute. Another important feature of the 1-s magnetograms is the presence of a plenty of specific disturbances caused by short-period geomagnetic pulsations, which must be retained in the definitive records. Thus, creating an instrument for formalized and unified recognition of spikes on the preliminary 1-s magnetograms would largely solve the problem of labor-consuming manual preprocessing of the magnetic records. In the context of this idea, in the present paper, we focus on recognition of the spikes on the 1-s magnetograms as a key point of the problem. We describe here the new algorithm of pattern recognition, SPs, which is capable of automatically identifying the spikes on the 1-s magnetograms with a low probability of missed events and false alarms. The algorithm was verified on the real magnetic data recorded at the French observatory located on Easter Island in the Pacific.

  14. Effects of geomagnetic storm on low latitude ionospheric total electron content: A case study from Indian sector

    NASA Astrophysics Data System (ADS)

    Chakraborty, Monti; Kumar, Sanjay; De, Barin Kumar; Guha, Anirban

    2015-07-01

    The effect of geomagnetic storms on low latitude ionosphere has been investigated with the help of Global Positioning System Total Electron Content (GPS-TEC) data. The investigation has been done with the aid of TEC data from the Indian equatorial region, Port Blair (PBR) and equatorial ionization anomaly region, Agartala (AGR). During the geomagnetic storms on 24th April and 15th July 2012, significant enhancement up to 150% and depression up to 72% in VTEC is observed in comparison to the normal day variation. The variations in VTEC observed from equatorial to EIA latitudes during the storm period have been explained with the help of electro-dynamic effects (prompt penetration electric field (PPEF) and disturbance dynamo electric field (DDEF)) as well as mechanical effects (storm-induced equatorward neutral wind effect and thermospheric composition changes). The current study points to the fact that the electro-dynamic effect of geomagnetic storms around EIA region is more effective than at the lower latitude region. Drastic difference has been observed over equatorial region (positive storm impact) and EIA region (negative storm impact) around same longitude sector, during storm period on 24th April. This drastic change as observed in GPS-TEC on 24th April has been further confirmed by using the O/N2 ratio data from GUVI (Global Ultraviolet Imager) as well as VTEC map constructed from IGS data. The results presented in the paper are important for the application of satellite-based communication and navigational system.

  15. Statistical analysis of the ionospheric response during geomagnetic storm conditions over South Africa using ionosonde and GPS data

    NASA Astrophysics Data System (ADS)

    Matamba, Tshimangadzo Merline; Habarulema, John Bosco; McKinnell, Lee-Anne

    2015-09-01

    This paper presents a statistical analysis of ionospheric response over ionosonde stations Grahamstown (33.3°S, 26.5°E, geographic) and Madimbo (22.4°S, 30.9°E, geographic), South Africa, during geomagnetic storm conditions which occurred during the period 1996-2011. Such a climatological study is important in establishing local ionospheric behavior trend which later forms a basis for accurate modeling and forecasting electron density and critical frequency of the F2 layer (foF2) useful for high-frequency communication. The analysis was done using foF2 and total electron content (TEC), and to identify the geomagnetically disturbed conditions, the Dst index with a storm criterion of Dst ≤ nT was used. Results show a strong solar cycle dependence with negative ionospheric storm effects following the solar cycle and positive ionospheric storm effects occurring most frequently during solar minimum. Seasonally, negative and positive ionospheric storm effects occurred most in summer (63.24%) and in winter (53.62%), respectively. An important finding is that only negative ionospheric storms were observed during great geomagnetic storm activity (Dst ≤ nT). For periods when both foF2 and TEC data (from colocated ionosonde and GPS receiver stations) were available, a similar response in terms of variational trend was observed. Hence, GPS data can be used to effectively identify the ionospheric response in the absence of ionosonde data.

  16. Vehicle Disturbance Test

    NASA Astrophysics Data System (ADS)

    Clapp, Brian

    2009-07-01

    The purpose of the VDT is to measure and characterize uncompensated environmental disturbances acting upon the HST during normal operation. The VDT is a passive test {not a forced-response test} used to obtain signatures for both externally induced {e.g. SCM, SA-3, SSM thermal gradients} and internally induced {e.g. HGA, RWA, COS and WFC3 mechanisms} disturbances affecting HST LOS pointing. The disturbances observed will be used as the nominal on-orbit disturbances in pointing control simulations until the next VDT is run.The test occurs after release, and most of the VDT can be run during the BEA period. The ?V1 sunpoint portion of the VDT usually occurs after the BEA period is complete. The VDT shall consist of two separate tests that need not occur consecutively. The overall duration of the VDT is at least 13 orbits of spacecraft time including {1} at least 8 orbits at +V3 sunpoint after achieving thermal equilibrium {at least 36-hours at +V3 sunpoint} and three out of 8-orbits have RWA Friction Compensation turned Off, and {2} at least 5 orbits at ?V1 sunpoint {all or part of this segment have RWA Friction Compensation turned Off}. At the beginning of each test, the attitude control law gains are switched to maneuver gains, and the gyros are commanded to low mode. The nominal attitude control law configuration will be restored at the end of each test.Each test is initiated via SMS execution of stored program macros in the HST flight computer to switch the attitude control law gains to low-bandwidth maneuver gains, command the gyros into low mode, terminate Velocity aberration and parallax {VAP} processing, and manage the status of on-board RWA Friction Compensation. The nominal attitude control law configuration will be restored at the end of each test via SMS execution of stored program macros. The stored program command macros are developed specifically for the VDT by the Flight Software and Pointing Control System groups.

  17. High Amplitude Events in relation to Interplanetary disturbances

    NASA Astrophysics Data System (ADS)

    Mishra, Rajesh Kumar; Agarwal Mishra, Rekha

    2012-07-01

    The Sun emits the variable solar wind which interacts with the very local interstellar medium to form the heliosphere. Hence variations in solar activity strongly influence interplanetary space, from the Sun's surface out to the edge of the heliosphere. Superimposed on the solar wind are mass ejections from the Sun and/or its corona which, disturb the interplanetary medium - hence the name "interplanetary disturbances". Interplanetary disturbances are the sources of large-scale particle acceleration, of disturbances in the Earth's magnetosphere, of modulations of galactic cosmic rays in short, they are the prime focus for space weather studies. The investigation deals with the study of cosmic ray intensity, solar wind plasma and interplanetary magnetic field parameters variation due to interplanetary disturbances (magnetic clouds) during an unusual class of days i.e. high amplitude anisotropic wave train events. The high amplitude anisotropic wave train events in cosmic ray intensity has been identified using the data of ground based Goose Bay neutron monitor and studied during the period 1981-94. Even though, the occurrence of high amplitude anisotropic wave trains does not depend on the onset of interplanetary magnetic clouds. But the possibility of occurrence of these events cannot be overlooked during the periods of interplanetary magnetic cloud events. It is observed that solar wind velocity remains higher (> 300) than normal and interplanetary magnetic field B remains lower than normal on the onset of interplanetary magnetic cloud during the passage of these events. It is also noted from the superposed epoch analysis of cosmic ray intensity and geomagnetic activity for high amplitude anisotropic wave train events during the onset of interplanetary magnetic clouds that the increase in cosmic ray intensity and decrease in geomagnetic activity start not at the onset of magnetic clouds but after few days. The north south component of IMF (Bz), IMF (B), proton

  18. Sleep Disturbances in Neurodevelopmental Disorders.

    PubMed

    Robinson-Shelton, Althea; Malow, Beth A

    2016-01-01

    Sleep disturbances are extremely prevalent in children with neurodevelopmental disorders compared to typically developing children. The diagnostic criteria for many neurodevelopmental disorders include sleep disturbances. Sleep disturbance in this population is often multifactorial and caused by the interplay of genetic, neurobiological and environmental overlap. These disturbances often present either as insomnia or hypersomnia. Different sleep disorders present with these complaints and based on the clinical history and findings from diagnostic tests, an appropriate diagnosis can be made. This review aims to provide an overview of causes, diagnosis, and treatment of sleep disturbances in neurodevelopmental disorders that present primarily with symptoms of hypersomnia and/or insomnia. PMID:26719309

  19. Robustness of disturbance attenuation with respect to disturbance model uncertainty

    NASA Astrophysics Data System (ADS)

    Davison, Daniel Edward

    In contrast to the case of robustness with respect to plant model uncertainty, the control systems community has paid relatively little attention to the issue of robustness with respect to disturbance model uncertainty. However, disturbance model uncertainty is of significance in many practical problems, including, for example, aircraft control (where the disturbance is turbulence), ship control (where the disturbances are wind and waves), and active suspension problems (where the disturbance is road roughness). Motivated, in particular, by turbulence model uncertainty, this dissertation considers the analysis and design of linear time-invariant controllers that are robust with respect to uncertainty in the disturbance intensity and bandwidth, where disturbance attenuation is measured by the output variance. Five aspects of the robust disturbance attenuation problem are considered. First, an expression for the output variance in terms of the uncertain disturbance parameters is derived. This expression is written in terms of an operator called the V-transform. Second, the notions of disturbance gain margin and disturbance bandwidth margin are introduced as quantitative measures of robustness with respect to uncertainty in the disturbance gain and disturbance bandwidth, respectively. Third, lower bounds on the achievable output variance are found under constraints of practical importance, e.g., constraints on bandwidth and stability robustness. The lower bounds are used to show that, in almost every practical situation, there is a limitation on both the achievable nominal performance and the achievable robustness margins. Fourth, tradeoffs between nominal performance and robust performance are investigated. The main result is that good nominal and good robust performance are neither incompatible nor equivalent. Fifth, a design procedure to achieve a prespecified level of robustness is proposed; the principal idea is to reduce the robust performance design problem to

  20. Soil disturbance by airbags

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Disturbance of the drift at the Pathfinder landing site reveals a shallow subsurface that is slightly darker but has similar spectral properties. The top set of images, in true color, shows the soils disturbed by the last bounce of the lander on its airbags before coming to rest and the marks created by retraction of the airbags. In the bottom set of images color differences have been enhanced. The mast at center is the Atmospheric Structure Instrument/Meteorology Package (ASI/MET). The ASI/MET is an engineering subsytem that acquired atmospheric data during Pathfinder's descent, and will continue to get more data through the entire landed mission. A shadow of the ASI/MET appears on a rock at left.

    Mars Pathfinder was developed and managed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  1. Postoperative circadian disturbances.

    PubMed

    Gögenur, Ismail

    2010-12-01

    An increasing number of studies have shown that circadian variation in the excretion of hormones, the sleep wake circle, the core body temperature rhythm, the tone of the autonomic nervous system and the activity rhythm are important both in health and in disease processes. An increasing attention has also been directed towards the circadian variation in endogenous rhythms in relation to surgery. The attention has been directed to the question whether the circadian variation in endogenous rhythms can affect postoperative recovery, morbidity and mortality. Based on the lack of studies where these endogenous rhythms have been investigated in relation to surgery we performed a series of studies exploring different endogenous rhythms and factors affecting these rhythms. We also wanted to examine whether the disturbances in the postoperative circadian rhythms could be correlated to postoperative recovery parameters, and if pharmacological administration of chronobiotics could improve postoperative recovery. Circadian rhythm disturbances were found in all the examined endogenous rhythms. A delay was found in the endogenous rhythm of plasma melatonin and excretion of the metabolite of melatonin (AMT6s) in urine the first night after both minor and major surgery. This delay after major surgery was correlated to the duration of surgery. The amplitude in the melatonin rhythm was unchanged the first night but increased in the second night after major surgery. The amplitude in AMT6s was reduced the first night after minimally invasive surgery. The core body temperature rhythm was disturbed after both major and minor surgery. There was a change in the sleep wake cycle with a significantly increased duration of REM-sleep in the day and evening time after major surgery compared with preoperatively. There was also a shift in the autonomic nervous balance after major surgery with a significantly increased number of myocardial ischaemic episodes during the nighttime period. The

  2. Plasmoid formation in geotail in the disturbed magnetosphere

    NASA Astrophysics Data System (ADS)

    Nazarkov, Ilya; Runov, Andrei; Kalegaev, Vladimir; Angelopoulos, Vassilis

    2016-07-01

    Magnetospheric conditions, responsible for drastic changes of geotail magnetic field, have been studied from the theoretical and experimental viewpoint. It was found that closed magnetic field structures (magnetic islands, or plasmoids) in the inner tail plasma sheet can arise when the magnetic flux through the tail lobes exceeds the threshold value that depends on the spatial sizes of the magnetosphere. In terms of the Earth's magnetosphere model A2000 a simple estimation of critical magnetic flux has been obtained. It was shown that the extremely quiet geomagnetic conditions in 2009 were responsible for the expansion of the magnetosphere that was favorable for the formation of the magnetic field structures like magnetic island in the inner geomagnetic tail. Such magnetic field configuration has been detected by Themis satellites during magnetic storm on 14 February 2009. The magnetospheric key parameters describing the large-scale current systems were determined using both satellite observations and/or calculations and the evolution of the magnetic field during disturbance has been reproduced in terms of A2000 model. It was shown that the formation of magnetic islands converts the magnetic flux through the tail lobes and prevents extremely strong development of the geotail magnetic field.

  3. Interplanetary magnetic sector polarity inferred from polar geomagnetic field observations

    NASA Technical Reports Server (NTRS)

    Eriss-Christensen, E.; Lassen, K.; Wilcox, J. M.; Gonzalez, W.; Colburn, D. S.

    1971-01-01

    With the use of a prediction technique it is shown that the polarity (toward or away from the sun) of the interplanetary magnetic field can be reliably inferred from observations of the polar geomagnetic field.

  4. Estimation of interplanetary electric field conditions for historical geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Veenadhari, B.; Tulasi Ram, S.; Selvakumaran, R.; Mukherjee, Shyamoli; Singh, Rajesh; Kadam, B. D.

    2015-09-01

    Ground magnetic measurements provide a unique database in understanding space weather. The continuous geomagnetic records from Colaba-Alibag observatories in India contain historically longest and continuous observations from 1847 to present date. Some of the super intense geomagnetic storms that occurred prior to 1900 have been revisited and investigated in order to understand the probable interplanetary conditions associated with intense storms. Following Burton et al. (1975), an empirical relationship is derived for estimation of interplanetary electric field (IEFy) from the variations of Dst index and ΔH at Colaba-Alibag observatories. The estimated IEFy values using Dst and ΔHABG variations agree well with the observed IEFy, calculated using Advanced Composition Explorer (ACE) satellite observations for intense geomagnetic storms in solar cycle 23. This study will provide the uniqueness of each event and provide important insights into possible interplanetary conditions for intense geomagnetic storms and probable frequency of their occurrence.

  5. Magnetospheric Energy Input during Intense Geomagnetic Storms in SC23

    NASA Astrophysics Data System (ADS)

    Besliu-Ionescu, Diana; Maris Muntean, Georgeta; Dobrica, Venera; Mierla, Marilena

    2015-04-01

    Geomagnetic storm connections to solar eruptive phenomena in solar cycle 23 (SC23) have been intensively studied and it is a subject of great importance because of their various effects in our day-to-day life. We analyse the energy transfer from the solar wind into the magnetosphere during intense geomagnetic storms defined by Dst ≤ -150 nT. There were 29 intense storms during SC23. We will use the Akasofu parameter (Akasofu, 1981) to compute the ɛ function and study its time profile. We compute the energy input efficiency during the main phase of the geomagnetic storm. We compute the magnetospheric energy input using the formula introduced by Wang et al. (2014) and compare these results with the ɛ function for the geomagnetic storms of October 29-30, 2003.

  6. Studying geomagnetic pulsation characteristics with the local approximation method

    NASA Astrophysics Data System (ADS)

    Getmanov, V. G.; Dabagyan, R. A.; Sidorov, R. V.

    2016-03-01

    A local approximation method based on piecewise sinusoidal models has been proposed in order to study the frequency and amplitude characteristics of geomagnetic pulsations registered at a network of magnetic observatories. It has been established that synchronous variations in the geomagnetic pulsation frequency in the specified frequency band can be studied with the use of calculations performed according to this method. The method was used to analyze the spectral-time structure of Pc3 geomagnetic pulsations registered at the network of equatorial observatories. Local approximation variants have been formed for single-channel and multichannel cases of estimating the geomagnetic pulsation frequency and amplitude, which made it possible to decrease estimation errors via filtering with moving weighted averaging.

  7. A comprehensive analysis of the geomagnetic storms occurred dur

    NASA Astrophysics Data System (ADS)

    Ghamry, Essam; Lethy, Ahmed; Arafa-Hamed, Tareq; Abd Elaal, Esmat

    2016-06-01

    The Geomagnetic storms are considered as one of the major natural hazards. Egyptian geomagnetic observatories observed multiple geomagnetic storms during 18 February to 2 March 2014. During this period, four interplanetary shocks successively hit the Earth's magnetosphere, leading to four geomagnetic storms. The storm onsets occurred on 18, 20, 23 and 27 February. A non-substorm Pi2 pulsation was observed on 26 February. This Pi2 pulsation was detected in Egyptian observatories (Misallat and Abu Simbel), Kakioka station in Japan and Carson City station in US with nearly identical waveforms. Van Allen Probe missions observed non-compressional Pc4 pulsations on the recovery phase of the third storm. This Pc4 event is may be likely attributed to the decay of the ring current in the recovery phase.

  8. A model of geomagnetic secular variation for 1980-1983

    USGS Publications Warehouse

    Peddie, N.W.; Zunde, A.K.

    1987-01-01

    We developed an updated model of the secular variation of the main geomagnetic field during 1980 through 1983 based on annual mean values for that interval from 148 worldwide magnetic observatories. The model consists of a series of 80 spherical harmonics, up to and including those of degree and order 8. We used it to form a proposal for the 1985 revision of the International Geomagnetic Reference Field (IGRF). Comparison of the new model, whose mean epoch is approximately 1982.0, with the Provisional Geomagnetic Reference Field for 1975-1980 (PGRF 1975), indicates that the moment of the centered-dipole part of the geomagnetic field is now decreasing faster than it was 5 years ago. The rate (in field units) indicated by PGRF 1975 was about -25 nT a-1, while for the new model it is -28 nT a-1. ?? 1987.

  9. New idea of geomagnetic monitoring through ENA detection from the International Space Station: ENAMISS project

    NASA Astrophysics Data System (ADS)

    Milillo, Anna; De Angelis, Elisabetta; Orsini, Stefano; Rubini, Alda; Evangelista, Yuri; Mura, Alessandro; Rispoli, Rosanna; Vertolli, Nello; Carrubba, Elisa; Donati, Alessandro; Di Lellis, Andrea Maria; Plainaki, Christina; Lazzarotto, Francesco

    2016-04-01

    , these latter having relevance in electric orbit raising, will be developed and made available for the satellite operators. Finally, a continuous global monitoring of the geomagnetic disturbances in the inner magnetosphere via ENA imaging from the ISS could represent an innovative Space Weather data product for European infrastructures dedicated to geomagnetic data distribution and now-cast services as for example ESPAS and the Space Situational Awareness (SSA) program of ESA.

  10. Global ionospheric effects of geomagnetic storm on May 2-3, 2010 and their influence on HF radio wave propagation

    NASA Astrophysics Data System (ADS)

    Kotova, Daria; Klimenko, Maxim; Klimenko, Vladimir; Zakharov, Veniamin

    2013-04-01

    geomagnetic storm. A comparison of the ordinary and extraordinary modes of HF radio ray paths in quiet and disturbed conditions has been done. We considered in more detail the features of the radio ray paths in the presence of F3 layer in the equatorial ionosphere, the main ionospheric trough and tongue of ionization at high latitudes. It is shown that the results obtained with use of radio propagation and GSM TIP models adequately describe HF radio ray paths in the Earth's ionosphere and can be used in applications. These investigations were carried out at financial support of Russian Foundation for Basic Research (RFBR) - Grant # 12-05-31217 and RAS Program 22.

  11. Ionospheric disturbances during November 30-December 1, 1988. XI - Abnormal propagations of HF and VHF radio waves

    NASA Astrophysics Data System (ADS)

    Ichinose, Masaru; Kamata, Mitsuhiro

    1992-07-01

    Unusual propagations of HF and VHF radio waves associated with a geomagnetic storm during the period from November 30 to December 1, 1988 are investigated using ionospheric data collected from Japan, China, and Taiwan. The increased field strength of the Japanese frequency standard signals (JJY 2.5 MHz and 5 MHz) which were received at Akita Radio Wave Observatory on the night of November 30 seem to have been caused by increased MUFs and/or scattering due to the disturbed ionosphere. The VHF-TV radio waves propagated from China were received at Kokubunji in Tokyo. One of the most probable mechanisms explaining this unusual propagation of VHF is a one-hop-F2 mode of propagation created by an ionosphere with an anomalously high f0F2. It was found out that these unusual HF and VHF propagations were attributed to unusual ionospheric conditions associated with these geomagnetic disturbances.

  12. The Geomagnetic Field and Radiation in Near-Earth Orbits

    NASA Technical Reports Server (NTRS)

    Heirtzler, J. R.

    1999-01-01

    This report shows, in detail, how the geomagnetic field interacts with the particle flux of the radiation belts to create a hazard to spacecraft and humans in near-Earth orbit. It illustrates the geometry of the geomagnetic field lines, especially around the area where the field strength is anomalously low in the South Atlantic Ocean. It discusses how the field will probably change in the future and the consequences that may have on hazards in near space.

  13. Detection and characterization of geomagnetic pulsations using HF ionospheric heating

    SciTech Connect

    Lee, H.S.; Ferraro, A.J.; Olson, J.V. Alaska Univ., Fairbanks )

    1990-12-01

    This paper describes the geomagnetic pulsations observed in the high-latitude ionosphere during an experiment dealing with the ionospheric generation of ELF/VLF EM waves in June and October 1987. There was clear evidence of geomagnetic pulsations intermixed with the ELF/VLF signals in both the magnitude and phase data. A simple simulation model is introduced to facilitate the interpretation of the data, and a procedure for characterizing the pulsation is described. 5 refs.

  14. Prediction of Solar Cycle 24 Using Geomagnetic Precursors: Validation and Update

    NASA Astrophysics Data System (ADS)

    Singh Dabas, Raj; Sharma, Kavita; Sarkar, S. K.

    Maximum amplitude of forthcoming solar cycle number 24 is predicted using geomagnetic precursor technique which is based on the correlation of geomagnetic indices (disturbances) prior to the minimum of the sunspot cycle with the magnitude of the ensuing solar cycle maximum. In the previous study Ap index was used as disturbance index which is available from the last 6-7 solar cycle only whereas long series of aa index is available for more than last 10-12 cycles. In the present study, instead of Ap, aa index is used to predict maximum amplitude of solar cycle 24. First, to validate earlier prediction (Dabas et al., 2008, Solar Phys. DOI 10.1007/s11207-008-9200-1), based on cycles 17-23, linear correlations are obtained between 12-month moving averages of the number of disturbed days when aa is greater than or equal to 50, called the disturbance index, DI, at thirteen selected times (called variate blocks 1, 2, . . . each of them in six-month duration) during the declining portion of the ongoing sunspot cycle and the maximum amplitude of the following sunspot cycle. As in the case of Ap, here again, variate block 9, which occurs exactly 48 months after the current cycle maximum or just prior to subsequent cycle minimum, gives the best correlation (0.97) with a minimum standard error of estimation of ±9, and hind casting shows agreement between predicted and observed maximum amplitudes to about 10 percent. As applied to cycle 24, with aa as precursors yields maximum amplitude of about 120±16 (the 90% prediction interval), which is very close to the earlier prediction of 124±23 (the 90% prediction interval) using Ap and hence validating the same. Further, the same method is applied to cycles 11-23 and once again the variate block 9, gives the best correlation (0.95) with a minimum standard error of estimation of ±13. The relation yields modified maximum amplitude for cycle 24 of about 130±20 (the 90% prediction interval) occurring about 44±4 months after its

  15. Coronal disturbances and their terrestrial effects /Tutorial Lecture/

    NASA Technical Reports Server (NTRS)

    Rust, D. M.

    1983-01-01

    An assessment is undertaken of recent approaches to the prediction of the interplanetary consequences of coronal disturbances, with attention to the relationships of shocks and energetic particles to coronal transients, of proton events to gamma-ray and microwave bursts, of geomagnetic storms to filament eruptions, and of solar wind increases to the flare site magnetic field direction. A discussion is given concerning the novel phenomenon of transient coronal holes, which appear astride the long decay enhancements of 2-50 A X-ray emission following H-alpha filament eruptions. These voids in the corona are similar to long-lived coronal holes, which are the sources of high speed solar wind streams. The transient coronal holes may also be associated with transient solar wind speed increases.

  16. Dependence of geosynchronous relativistic electron enhancements on geomagnetic parameters

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. V.; Chao, J. K.

    2003-11-01

    Relativistic electron fluxes observed in geosynchronous orbit by GOES-8 in 1997 to 2000 were considered as a complex function of geomagnetic indices PC, Kp, and Dst, as well as parameters of the magnetosphere size, subsolar Rs, and terminator Rf magnetopause distances. A geosynchronous relativistic electron enhancement (GREE) is determined as daily maximal electron flux exceeding the upper root mean square deviation (RMSD) threshold of about 1500 (cm2s sr)-1. Comparison analysis of the GREE dynamics and geomagnetic conditions on the rising phase of current solar cycle revealed suppression of the relativistic electron enhancements by substantially increased strong geomagnetic activity in the solar maximum. Statistical consideration of a relationship between the GREEs and the geomagnetic parameters showed that the most important parameters controlling the geosynchronous relativistic electron enhancements were 4-day averaged Kp index, PC index, and magnetopause termination distance Rf, delayed on 3 and 14 hours, respectively. Relatively high averaging time for Kp was explained by the cumulative effect of substorm energy release in a gradual mechanism accelerating the relativistic electrons in the magnetosphere. Very short time delay for PC index was interpreted as intensification of a fast acceleration mechanism producing the GREEs during severe geomagnetic storms. Substantial increase of the PC index (PC > 5) was found to be a sufficient condition for GREE occurrence. The fast response of the geosynchronous relativistic electron fluxes on the magnetosphere compression was explained by drift losses of the energetic electrons at the magnetopause, which approaches the Earth during geomagnetic storms.

  17. Automated detection of geomagnetic storms with heightened risk of GIC

    NASA Astrophysics Data System (ADS)

    Bailey, Rachel L.; Leonhardt, Roman

    2016-06-01

    Automated detection of geomagnetic storms is of growing importance to operators of technical infrastructure (e.g., power grids, satellites), which is susceptible to damage caused by the consequences of geomagnetic storms. In this study, we compare three methods for automated geomagnetic storm detection: a method analyzing the first derivative of the geomagnetic variations, another looking at the Akaike information criterion, and a third using multi-resolution analysis of the maximal overlap discrete wavelet transform of the variations. These detection methods are used in combination with an algorithm for the detection of coronal mass ejection shock fronts in ACE solar wind data prior to the storm arrival on Earth as an additional constraint for possible storm detection. The maximal overlap discrete wavelet transform is found to be the most accurate of the detection methods. The final storm detection software, implementing analysis of both satellite solar wind and geomagnetic ground data, detects 14 of 15 more powerful geomagnetic storms over a period of 2 years.

  18. Globally strong geomagnetic field intensity circa 3000 years ago

    NASA Astrophysics Data System (ADS)

    Hong, Hoabin; Yu, Yongjae; Lee, Chan Hee; Kim, Ran Hee; Park, Jingyu; Doh, Seong-Jae; Kim, Wonnyon; Sung, Hyongmi

    2013-12-01

    High-fidelity geomagnetic field intensity determination was carried out using 191 baked fragments collected from 20 kilns or hearths with ages ranging between ∼1200 BC and ∼AD 1725 in South Korea. Geomagnetic field intensity variation displayed three narrow minima at ∼800-700 BC, ∼AD 700, and ∼AD 1600 and two maxima at ∼1200-1100 BC and ∼AD 1000-1100. In most time intervals, virtual axial dipole moment (VADM) variation is confined within 20% of the present VADM. However, geomagnetic field intensity circa 3000 yr ago is nearly 40% larger than the present value. Such high VADMs circa 3000 yr ago are in phase with those in other longitudinal bands in northern hemisphere centered at 5E (France), 30E (the Middle East) and 200E (Hawaii). Although strong geomagnetic field intensity circa 3000 yr ago is globally synchronous, the highest VADM occurs at slightly different time intervals in different locations. Hence it is possible that the globally strong geomagnetic field intensity circa 3000 yr ago reflects the migration of persistent hemispheric flux in northern hemisphere or an episode of geomagnetic field hemispheric asymmetry.

  19. Geomagnetic storm environments and effects on electrical systems

    SciTech Connect

    Tesche, F.M. , Dallas, TX ); Barnes, P.R. )

    1992-01-01

    This paper briefly reviews the behavior of the earth's magnetic field during a geomagnetic storm. Temporal variations of the B-field on the earths surface can induce an electric field in the earth, and this E-field will induce currents to flow in long, grounded conductors. Previous experience with geomagnetic storms indicates that such geomagnetically-induced currents can cause damage to power system components, and at times, can cause power blackouts. This paper presents some recently measured geomagnetic field variations, and illustrates how the induced electric field can be calculated, assuming a simple model of the imperfectly conducting earth. This calculation may be performed either in the time or in the frequency domain. Approximations to the time dependence of the geomagnetic field permit an analytical evaluation of the corresponding E-field in the earth, and this results in a simple expression for the transient Enfield. A knowledge of this Enfield is important in understanding the effects of geomagnetic storms on the power system, and in devising protection methods.

  20. Are migrating raptors guided by a geomagnetic compass?

    USGS Publications Warehouse

    Thorup, Kasper; Fuller, Mark R.; Alerstam, T.; Hake, M.; Kjellen, N.; Standberg, R.

    2006-01-01

    We tested whether routes of raptors migrating over areas with homogeneous topography follow constant geomagnetic courses more or less closely than constant geographical courses. We analysed the routes taken over land of 45 individual raptors tracked by satellite-based radiotelemetry: 25 peregrine falcons, Falco peregrinus, on autumn migration between North and South America, and seven honey buzzards, Pernis apivorus, and 13 ospreys, Pandion haliaetus, on autumn migration between Europe and Africa. Overall, migration directions showed a better agreement with constant geographical than constant geomagnetic courses. Tracks deviated significantly from constant geomagnetic courses, but were not significantly different from geographical courses. After we removed movements directed far from the mean direction, which may not be migratory movements, migration directions still showed a better agreement with constant geographical than constant geomagnetic courses, but the directions of honey buzzards and ospreys were not significantly different from constant geomagnetic courses either. That migration routes of raptors followed by satellite telemetry are in closer accordance with constant geographical compass courses than with constant geomagnetic compass courses may indicate that geographical (e.g. based on celestial cues) rather than magnetic compass mechanisms are of dominating importance for the birds' long-distance orientation.

  1. Causes of the Sep. 12-13, 2014 geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Cho, Kyung-Suk; Kim, Rooksoon; Park, Sung-Hong; Kim, Sujin

    2015-08-01

    Solar cycle 24 is very modest compared to previous solar cycles. The solar maximum phase may have been reached in the middle of 2014 and the sunspot number has decreased since the beginning of 2015. During this period, it has been reported that only few events produced strong X-class flares, solar proton events, and geomagnetic storms. In this study we have investigated causes of the multiple geomagnetic storms occurred on September 12-13, 2014. The geomagnetic storm forecast model based on the CME observations was used for identification of the causes of the geomagnetic storms. Details of the solar source region were investigated to give an answer why the geomagnetic storms were not so strong even though they were related to fast coronal mass ejections with large earth-ward direction. As a result, we found that the first weak storm was driven by the CME related to M4.6 flare and the second minor storm was driven by one of the fast CMEs related to strong X1.6 flare. Our result shows that the reason why the second storm was not strong is that it was caused by the CME with northward magnetic field. Therefore we suggest that one of the essential ingredients for geomagnetic storm forecasting is to find out the magnetic field direction of earth-ward CMEs, which can be accomplished by investigating magnetic fields of their solar source regions a few days before their arrival to the earth.

  2. Geomagnetic storms, the Dst ring-current myth and lognormal distributions

    USGS Publications Warehouse

    Campbell, W.H.

    1996-01-01

    The definition of geomagnetic storms dates back to the turn of the century when researchers recognized the unique shape of the H-component field change upon averaging storms recorded at low latitude observatories. A generally accepted modeling of the storm field sources as a magnetospheric ring current was settled about 30 years ago at the start of space exploration and the discovery of the Van Allen belt of particles encircling the Earth. The Dst global 'ring-current' index of geomagnetic disturbances, formulated in that period, is still taken to be the definitive representation for geomagnetic storms. Dst indices, or data from many world observatories processed in a fashion paralleling the index, are used widely by researchers relying on the assumption of such a magnetospheric current-ring depiction. Recent in situ measurements by satellites passing through the ring-current region and computations with disturbed magnetosphere models show that the Dst storm is not solely a main-phase to decay-phase, growth to disintegration, of a massive current encircling the Earth. Although a ring current certainly exists during a storm, there are many other field contributions at the middle-and low-latitude observatories that are summed to show the 'storm' characteristic behavior in Dst at these observatories. One characteristic of the storm field form at middle and low latitudes is that Dst exhibits a lognormal distribution shape when plotted as the hourly value amplitude in each time range. Such distributions, common in nature, arise when there are many contributors to a measurement or when the measurement is a result of a connected series of statistical processes. The amplitude-time displays of Dst are thought to occur because the many time-series processes that are added to form Dst all have their own characteristic distribution in time. By transforming the Dst time display into the equivalent normal distribution, it is shown that a storm recovery can be predicted with

  3. Physical Meaning of the Equinoctial Effect for Seasonal Variation of Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Yoshida, A.

    2008-12-01

    The general tendency for magnetic disturbances to be more stormy at equinoxes than at solstices has been recognised for more than 150 years. To explain the seasonal variation three principal hypotheses have been proposed; the axial hypothesis (Cortie, 1912), the equinoctial hypothesis (Bartels, 1932; McIntosh, 1959), and the Russell and McPherron (RM) hypothesis (Russell and McPherron, 1973). The RM hypothesis, which is based on the recognition that the magnetic field in the solar equatorial plane tends to have the largest southward component in geocentric solar magnetospheric (GSM) coordinates in early April and October, has been largely accepted for many years. However, recent studies have confirmed that the RM effect accounts for only a subordinate proportion of the seasonal variation of geomagnetic activity, and that the larger part of the phenomenon is attributable to the equinoctial effect in which the angle between the solar wind flow and the dipole axis of the Earth plays an essential role (Cliver, Kamide and Ling, 2000; Cliver, Kamide, Ling and Yokoyama, 2001; O'Brien and McPherron, 2002). In this paper physical meaning of the equinoctial effect is investigated based on the data of three-hourly am index and solar wind parameters acquired by the ACE satellite. The am indices are well correlated with BsVxVx, where Bs is the southward component of the interplanetary magnetic field (IMF) and Vx is the solar wind velocity in the sun-earth direction. It is found, however, that the am - BsVxVx relation depends on the range of VxVx: The am in higher ranges of VxVx tends to be larger than am in lower ranges of VxVx for both equinoctial and solstitial epochs for the same value of BsVxVx. Using the data sets of the same VxVx range, it is shown that distribution of points in the am - BsVxVx diagram at the solstitial epochs overlaps with that at the equinoctial epochs and the average am values in each BsVxVx bin in solstitial epochs are almost equal to those in

  4. 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

  5. A statistical analysis on the correlation between LF signal disturbances and strong earthquakes

    NASA Astrophysics Data System (ADS)

    Rozhnoi, Alexander; Solovieva, Maria; Molchanov, Oleg; Hayakawa, Masashi; Biagi, Pier Francesco; Schwingenschuh, Konrad

    2010-05-01

    Data of seven years observations in Petropavlovsk-Kamchatsky are used for further statistical study on the correlation between disturbances in subionospheric LF signal and strong earthquakes. Nighttime difference amplitude and phase of the signal 40 kHz from JJY transmitter in Japan are analysed. It is found that anomalies of LF signal are observed in 15-20 % cases for earthquakes with М=5.5-6.5. The signal behavior about the date of nine the strongest earthquakes with М≥7, which occurred in the wave path sensitivity zone during 2000-2008, is analysed in detail. Clear anomalies in amplitude and phase of the signal are observed in five cases for quiet geomagnetic conditions. In two cases earthquakes were preceded by strong geomagnetic activity which could obscure effect from earthquakes. These results confirm our previous statistical works and testify the efficiency of VLF/LF radio signal method for strong earthquakes forecast.

  6. The magnetospheric disturbance ring current as a source for probing the deep earth electrical conductivity

    USGS Publications Warehouse

    Campbell, W.H.

    1990-01-01

    Two current rings have been observed in the equatorial plane of the earth at times of high geomagnetic activity. An eastward current exists between about 2 and 3.5 earth radii (Re) distant, and a larger, more variable companion current exists between about 4 and 9 Re. These current regions are loaded during geomagnetic substorms. They decay, almost exponentially, after the cessation of the particle influx that attends the solar wind disturbance. This review focuses upon characteristics needed for intelligent use of the ring current as a source for induction probing of the earth's mantle. Considerable difficulties are found with the assumption that Dst is a ring-current index. ?? 1990 Birkha??user Verlag.

  7. A Quaternary Geomagnetic Instability Time Scale

    NASA Astrophysics Data System (ADS)

    Singer, B. S.

    2013-12-01

    Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought

  8. A case study of ionospheric storm effects during long-lasting southward IMF Bz-driven geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Liu, Libo; Nakamura, Takuji; Zhao, Biqiang; Ning, Baiqi; Yoshikawa, A.

    2014-09-01

    Multiple instrumental observations including GPS total electron content (TEC), foF2 and hmF2 from ionosondes, vertical ion drift measurements from Communication/Navigation Outage Forecasting System, magnetometer data, and far ultraviolet airglow measured by Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Global Ultraviolet Imager (TIMED/GUVI) are used to investigate the profound ionospheric disturbances at midlatitude and low latitude during the 14-17 July 2012 geomagnetic storm event, which was featured by prolonged southward interplanetary geomagnetic field component for about 30 h below -10 nT. In the East Asian/Australian sector, latitudinal profile of TEC variations in the main phase were characterized by three bands of increments and separated by weak depressions in the equatorial ionospheric anomaly (EIA) crest regions, which were caused by the combined effects of disturbance dynamo electric fields (DDEF) and equatorward neutral winds. In the recovery phase, strong inhibition of EIA occurred and the summer crest of EIA disappeared on 16 July due to the combined effects of intrusion of neutral composition disturbance zone as shown by the TIMED/GUVI O/N2 measurements and long-lasting daytime westward DDEF inferred from the equatorial electrojet observations. The transit time of DDEF over the dip equator from westward to eastward is around 2200 LT. In the American longitude, the salient ionospheric disturbances in the summer hemisphere were characterized by daytime periodical intrusion of negative phase for three consecutive days in the recovery phase, preceded by storm-enhanced density plume in the initial phase. In addition, multiple short-lived prompt penetration electric fields appeared during stable southward interplanetary magnetic field (IMF) Bz in the recovery phase and were responsible for enhanced the EIA and equatorial ionospheric uplift around sunset.

  9. A case study of Ionospheric storm effects during long-lasting southward IMF Bz driven geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Liu, J., Sr.

    2014-12-01

    Multiple instrumental observations including GPS TEC, foF2 and hmF2 from ionosondes, vertical ion drift measurements from C/NOFS, magnetometer data and far-ultraviolet airglow measured by TIMED/GUVI are used to investigate the profound ionospheric disturbances at mid- and low-latitudes during the 14-17 July 2012 geomagnetic storm event, which was featured by prolonged southward interplanetary geomagnetic field component for about 30 hours below -10 nT. In the East Asian/Australian sector, latitudinal profile of TEC variations in the main phase were characterized by three bands of increments and separated by weak depressions in the Equatorial Ionospheric Anomaly (EIA) crest regions, which were caused by the combined effects of disturbance dynamo electric fields (DDEF) and equatorward neutral winds. In the recovery phase, strong inhibition of EIA occurred and the summer crest of EIA disappeared on 16 July due to the combined effects of intrusion of neutral composition disturbance zone as shown by the TIME/GUVI O/N2 measurements and long-lasting daytime westward DDEF inferred from the equatorial electric electrojet (EEJ) observations. The transit time of DDEF over the dip equator from westward to eastward is around 2200 LT. In the American longitude, the salient ionospheric disturbances in the summer hemisphere were characterized by daytime periodical intrusion of negative phase for three consecutive days in the recovery phase, preceded by storm enhanced density (SED) plume in the initial phase. In addition, multiple short-lived prompt penetration electric fields (PPEF) appeared during stable southward IMF Bz in the recovery phase and were responsible for enhanced the EIA and equatorial ionospheric uplift around sunset.

  10. Plasma drifts and polarization electric fields associated with TID-like disturbances in the low-latitude ionosphere: C/NOFS observations

    NASA Astrophysics Data System (ADS)

    Huang, Chao-Song

    2016-02-01

    Medium-scale traveling ionospheric disturbances are often observed at the magnetically conjugate points in the nighttime midlatitude ionosphere. It has been suggested that gravity waves disturb the ionosphere and induce electric fields in one hemisphere and that the electric fields are amplified by the Perkins instability and transmitted along the geomagnetic field lines to the conjugate ionosphere, creating similar disturbances there. However, direct observations of electric fields associated with traveling ionospheric disturbances (TIDs) are very few. In this study, we present low-latitude TID-like disturbances observed by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. It is found that ion velocity perturbations are generated in the directions parallel and perpendicular to the geomagnetic field within TIDs. Both the parallel and perpendicular ion velocity perturbations show an in-phase correlation with the ion density perturbations. For nighttime TIDs, the amplitude of both the parallel and meridional ion velocity perturbations increases almost linearly with the amplitude of the ion density perturbations, and the meridional ion drift is proportional to the parallel ion velocity. For daytime TIDs, the parallel ion velocity perturbation increases with the ion density perturbation, but the meridional ion velocity perturbation does not change much. The observations provide evidence that polarization electric field is generated within TIDs at low latitudes and maps along the geomagnetic field lines over a large distance.

  11. Influence of geomagnetic storms of September 26-30, 2011, on the ionosphere and HF radiowave propagation. I. Ionospheric effects

    NASA Astrophysics Data System (ADS)

    Klimenko, M. V.; Klimenko, V. V.; Bessarab, F. S.; Ratovsky, K. G.; Zakharenkova, I. E.; Nosikov, I. A.; Stepanov, A. E.; Kotova, D. S.; Vorobjev, V. G.; Yagodkina, O. I.

    2015-11-01

    Geomagnetic storm ionospheric effects observed at different latitudes and longitudes on September 26 and 28-30, 2011, are interpreted with the GSM TIP model. It has been justified that the results of this model can subsequently be used to calculate the HF radiowave ray tracing under quiet conditions and for the selected dates in September 2011. The model calculations are compared with observations of the ionospheric parameters performed by different radiophysical methods. The presented results confirm the classical mechanisms by which positive and negative ionospheric storms are formed during the main phase of a geomagnetic storm. At high latitudes, the electron density is mainly disturbed due to changes in the neutral composition of the thermosphere, resulting in an increase in the chemical loss rates, and the electromagnetic drift, which results in a substantial reconstruction of the high-latitude ionosphere owing to the horizontal plasma transfer. During the storm recovery phase at midlatitudes, electron density positive disturbances are formed in the daytime due to an increase in the n(O)/ n(N2) ratio; at the same time, negative effects in the electron density are formed at night as a result of plasma tube devastation. Comparison with the observations indicates that the presented model calculation results can be used to describe a medium for solving problems of radiowave propagation in the ionosphere during the storm main phase on September 26 and during the recovery phase on September 28-30, 2011.

  12. Observation of MSTIDs in Geomagnetic Conjugate Points, observed by all-sky images of OI 630.0 nm emission

    NASA Astrophysics Data System (ADS)

    Stefanello, Michel; Schuch, Nelson Jorge; Sarzi Machado, Cristiano; Pimenta, Alexandre; Vestena Bilibio, Anderson; Amorim, Danielle; Andrioli, Vania Fatima

    Medium Scale Traveling Ionospheric Disturbances (MSTIDs) are characterized as wave-like structures which propagate in the ionospheric F region of low and medium latitudes. Its origin is attributed to electrodynamics instabilities processes explained by Perkins Plasma Instability Theory. This study presents an observation of simultaneous occurrence of Medium Scale Traveling Ionospheric Disturbance (MSTID) in both hemispheres, during geomagnetically quiet nights. All-sky images of OI 630.0 nm emission were obtained with two imagers localized in geomagnetic conjugate points: Southern Space Observatory (29.4ºS, 53.8ºW), in São Martinho da Serra, Southern Brazil, and Arecibo Observatory (18.3ºN, 66.7ºW), in Puerto Rico. Using two digisondes installed at Falkland Islands (51.4ºS, 57.5ºW) and Puerto Rico (18.5ºN, 67.1ºW), it was investigated the behavior of F region during the occurrence the MSTIDs. Data from GPS receivers installed at Santa Maria (29.7ºS, 53.7ºW) and Virgin Islands (17.7ºN, 64.7ºW) were employed to calculate the variation of the Total Electronic Content (TEC). The analysis of TEC allows to identify the occurrence of ionospheric irregularities, such as MSTIDs.

  13. Electric currents above Saint-Santin 3. A preliminary study of disturbances: June 6, 1978; March 22, 1979; March 23, 1979

    SciTech Connect

    Mazaudier, C.

    1985-02-01

    This paper presents three case studies of ionospheric disturbances in electric fields, currents, and winds during periods of geomagnetic storms. These disturbances are detected by the Saint-Santin incoherent scatter radar. The disturbances are shown to originate from two distinct physical mechanism: (1) penetration of electric fields to lower latitudes during times of rapid change in magnetospheric convection; and (2) the action of the disturbed ionospheric dynamo driven by storm-induced wind disturbances. The storm of June 6, 1978, shows a simple illustration of penetrative convection electric fields. The storm of March 22, 1979, gives additional examples of this effect both when the B/sub Z/ component of the interplanetary fields turns southward and northward. The observed events on March 23 are clearly identifiable as the delayed response of the disturbance ionospheric dynamo.

  14. MHD simulation of the interplanetary environment in the ecliptic plane during the 3-9 February 1986 solar and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Dryer, M.; Smith, Z. K.; Detman, T. R.; Yeh, T.

    1986-09-01

    A numerical simulation is performed for the interplanetary medium's response to 6 solar flares that were observed, sequentially, in real time by NOAA and AWS instruments 3-7 Feb 1986. This report is of great practical interest because of the extensive geomagnetic disturbances and associated near-Earth activity that followed these flares on 6-9 Feb. The magnetohydrodynamic simulation is carried out with the Space Environment Laboratory's 2-1/2D Interplanetary Global Model code. It demonstrates the multiple, compound interactions of the interplanetary disturbances produced by these flares by using input perturbations based upon real-time optical, radio, and satellite observations. The optical (H-alpha) and radio (microwave to metric wavelength) data were obtained from the SOON/RSTN sites, and full-disk-integrated X-ray measurements were obtained from the NOAA/GOES-5 and -6 satellites. Examination of the simulated solar wind output (such as momentum flux, and cross-magnetospheric tail electric field) at Earth's position indicates that the major geomagnetic activity was probably due primarily to the second and fifth solar flares in the sixfold sequence. Predicated geomagnetic storm sudden commencement times were early by only about 4% (3-4 hours) for the pulses suggested by the consequences of the 2d and 6th flares. The 180 hour simulation, which required only 100 seconds (CPU time) on the NOAA/NBS CYBER 855/205, required 8 hours clock time on the SEL's APOLLO workstation.

  15. Sleep Disturbances in Mood Disorders.

    PubMed

    Rumble, Meredith E; White, Kaitlin Hanley; Benca, Ruth M

    2015-12-01

    The article provides an overview of common and differentiating self-reported and objective sleep disturbances seen in mood-disordered populations. The importance of considering sleep disturbances in the context of mood disorders is emphasized, because a large body of evidence supports the notion that sleep disturbances are a risk factor for onset, exacerbation, and relapse of mood disorders. In addition, potential mechanisms for sleep disturbance in depression, other primary sleep disorders that often occur with mood disorders, effects of antidepressant and mood-stabilizing drugs on sleep, and the adjunctive effect of treating sleep in patients with mood disorders are discussed. PMID:26600106

  16. Intensity and Variability of Geomagnetic Time Derivatives

    NASA Astrophysics Data System (ADS)

    Jackel, B. J.; Connors, M. G.; Reiter, K.; Singleton, M.

    2015-12-01

    Time derivatives of the geomagnetic field are studied for more than a decade of observations at more than a dozen sites in northern Canada. In the auroral zone the derivative magnitude observed by 5-second fluxgate magnetometers often has a lognormal distribution. Parameter estimates corresponding to intensity (log-mean) and variability (log-variance) are nearly independent and have very different statistical properties. Variability is essentially a random variable, while intensity autocorrelation times are on the order of tens of minutes. Observed intensities are highly correlated with AE, and increase with solar wind speed and the magnitude of Bz<0. Both variability and intensity have local-time maxima before and after midnight, but with different patterns that combine to produce a larger post-midnight peak. Post-midnight variability is almost completely determined by latitude, with largest values at subauroral sites and smallest values in the polar cap. Intensity depends on latitude, but also has a site-specific element which may be due to local conductivity.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Equatorial airglow and the ionospheric geomagnetic anomaly.

    NASA Technical Reports Server (NTRS)

    Chandra, S.; Reed, E. I.; Troy, B. E., Jr.; Blamont, J. E.

    1973-01-01

    Ogo 4 observations of the O I (6300-A) emissions have revealed a global pattern hitherto undetected from the ground-based observations. It is seen that the postsunset emission of O I (6300 A) in October 1967 is very asymmetrical with respect to the geomagnetic equator in certain longitude regions and shows poor correlation with the electron density measured simultaneously from the same spacecraft. This asymmetry is less marked in the UV airglow, O I (1356 A), which appears to vary as the square of the maximum electron density in the F region. The horizon scan data of the 6300-A airglow reveal that the latitudinal asymmetry is associated with asymmetry in the height of the O I (6300-A) emission and hence with the altitude of the F2 peak. From the correlative studies of the airglow and the ionospheric measurements the mechanisms of the UV and the 6300 A emissions are discussed in terms of the processes involving radiative and dissociative recombination. Theoretical expressions are developed which relate the airglow data to the ionospheric parameters.

  2. Geomagnetic main field modeling with DMSP

    NASA Astrophysics Data System (ADS)

    Alken, P.; Maus, S.; Lühr, H.; Redmon, R. J.; Rich, F.; Bowman, B.; O'Malley, S. M.

    2014-05-01

    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, Ørsted, and SAC-C. With the completion of the CHAMP mission in 2010, there has been a multiyear gap in satellite-based vector magnetic field measurements available for main field modeling. In this study, we calibrate the special sensor magnetometer instrument on board DMSP to create a data set suitable for main field modeling. These vector field measurements are calibrated to compute instrument timing shifts, scale factors, offsets, and nonorthogonality angles of 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 15 main field model to the data set and compare with the World Magnetic Model and Ørsted scalar measurements. We call this model DMSP-MAG-1, and its coefficients and software are available for download at http://geomag.org/models/dmsp.html. Our results indicate that the DMSP data set will be a valuable source for main field modeling for the years between CHAMP and the recently launched Swarm mission.

  3. The High-Risk (Disturbed and Disturbing) College Student

    ERIC Educational Resources Information Center

    Hollingsworth, Kathy R.; Dunkle, John H.; Douce, Louise

    2009-01-01

    The disturbed and disturbing college student causes the most vexing concerns for student affairs administrators. The Assessment-Intervention of Student Problems (AISP) model offers a useful and easily understood framework for dealing with the various challenges of this high-risk student population. This chapter focuses on changes that have…

  4. Hostility disturbs learning.

    PubMed

    Shimojima, Yumi; Tujii, Takeo; Yanagisawa, Atsuo; Tajino, Kazuhiro; Kanda, Hiroko; Yamagami, Masako

    2003-04-01

    Many studies have shown that there is a strong correlation between hostility and coronary artery disease; however, the pathogenic mechanisms by which hostility causes coronary artery disease have not been identified. Several studies have shown that hostility is associated with increased cardiovascular reactivity to mental stress. Sloan and colleagues used mental arithmetic and the Stroop Color-Word Task as psychological stressors and suggested that hostility is associated with diminished cardiac vagal control. It is supposed that the diminished cardiac vagal control results in uncontrollability of increased heart rate under stressful conditions so performance on mental stress tasks is poor. However, performance was not analyzed on the Stroop Color-Word Task. If hostility influences the autonomic nervous system, the performance of this mental stress task may also differ according to extent of hostility. In the present study, whether hostility disturbed performance of a mental stress task and the practice on it was examined. Subjects completed the Cook-Medley Hostility Scale and were divided into three groups (High, Middle, and Low) by their total scores and three subscales (Cynicism, Hostile Affect, and Aggressive Responding). They also completed the Stroop Color-Word Task. Analysis showed practice by High and Middle scoring groups on Aggressive Responding had a significantly smaller effect than that by Low scoring groups. The pathogenic mechanisms by which hostility may underlie coronary artery disease were discussed. PMID:12776844

  5. A method for separating seismo-ionospheric TEC outliers from heliogeomagnetic disturbances by using nu-SVR

    SciTech Connect

    Pattisahusiwa, Asis; Liong, The Houw; Purqon, Acep

    2015-09-30

    Seismo-Ionospheric is a study of ionosphere disturbances associated with seismic activities. In many previous researches, heliogeomagnetic or strong earthquake activities can caused the disturbances in the ionosphere. However, it is difficult to separate these disturbances based on related sources. In this research, we proposed a method to separate these disturbances/outliers by using nu-SVR with the world-wide GPS data. TEC data related to the 26th December 2004 Sumatra and the 11th March 2011 Honshu earthquakes had been analyzed. After analyzed TEC data in several location around the earthquake epicenter and compared with geomagnetic data, the method shows a good result in the average to detect the source of these outliers. This method is promising to use in the future research.

  6. Subclassification of School Phobic Disturbances.

    ERIC Educational Resources Information Center

    Atkinson, Leslie; And Others

    The confusion surrounding all aspects of school refusal may rest partly on the misguided assumption that the disturbance represents a single syndrome. Five consistently emerging variables which may help distinguish among school phobic types were abstracted from the literature: extensiveness of disturbance, mode of onset, age, fear source, and…

  7. Using IRI and GSM TIP model results as environment for HF radio wave propagation model during the geomagnetic storm occurred on September 26-29, 2011

    NASA Astrophysics Data System (ADS)

    Kotova, D. S.; Klimenko, M. V.; Klimenko, V. V.; Zakharov, V. E.; Ratovsky, K. G.; Nosikov, I. A.; Zhao, B.

    2015-11-01

    This paper analyses the geomagnetic storm on September 26-29, 2011. We compare the calculation results obtained using the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) and IRI-2012 (Bilitza et al., 2014) model with ground-based ionosonde data of stations at different latitudes and longitudes. We examined physical mechanisms responsible for the formation of ionospheric effects during the main phase of geomagnetic storm that occurred at the rising phase of the 24th solar cycle. We used numerical results obtained from IRI-2012 and GSM TIP models as propagation environment for HF signals from an equatorial transmitter during quiet and disturbed conditions. We used the model of HF radio wave propagation developed in I. Kant Baltic Federal University (BFU) that is based on the geometrical optics approximation. We compared the obtained radio paths in quiet conditions and during the main and recovery storm phases and evaluated radio wave attenuation in different media models.

  8. Global Magnetosphere Evolution During 22 June 2015 Geomagnetic Storm as Seen From Multipoint Observations and Comparison With MHD-Ring Rurrent Model

    NASA Astrophysics Data System (ADS)

    Buzulukova, N.; Moore, T. E.; Dorelli, J.; Fok, M. C. H.; Sibeck, D. G.; Angelopoulos, V.; Goldstein, J.; Valek, P. W.; McComas, D. J.

    2015-12-01

    On 22-23 June 2015 a severe geomagnetic storm occurred with Dst minimum of approximately -200nT. During this extreme event, multipoint observations of magnetospheric dynamics were obtained by a fleet of Geospace spacecraft including MMS, TWINS, Van-Allen and THEMIS. We present analysis of satellite data during that event, and use a global coupled MHD-ring current model (BATSRUS-CRCM) to connect multipoint observations from different parts of the magnetosphere. The analysis helps to identify different magnetospheric domains from multipoint measurements and various magnetospheric boundary motions. We will explore how the initial disturbance from the solar wind propagates through the magnetosphere causing energization of plasma in the inner magnetosphere and producing an extreme geomagnetic storm.

  9. Satellite accelerometer measurements of neutral density and winds during geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Marcos, F. A.; Forbes, J. M.

    1986-01-01

    A new thermospheric wind measurement technique is reported which is based on a Satellite Electrostatic Triaxial Accelerometer (SETA) system capable of accurately measuring accelerations in the satellite's in-track, cross-track and radial directions. Data obtained during two time periods are presented. The first data set describes cross-track winds measured between 170 and 210 km during a 5-day period (25 to 29 March 1979) of mostly high geomagnetic activity. In the second data set, cross-track winds and neutral densities from SETA and exospheric temperatures from the Millstone Hill incoherent scatter radar are examined during an isolated magnetic substorm occurring on 21 March 1979. A polar thermospheric wind circulation consisting of a two cell horizontal convection pattern is reflected in both sets of cross-track acceleration measurements. The density response is highly asymmetric with respect to its day/night behavior. Latitude structures of the density response at successive times following the substorm peak suggest the equatorward propagation of a disturbance with a phase speed between 300 and 600 m/s. A deep depression in the density at high latitudes (less than 70 deg) is evident in conjunction with this phenomenon. The more efficient propagation of the disturbance to lower latitudes during the night is probably due to the midnight surge effect.

  10. 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

  11. High latitude TEC fluctuations and irregularity oval during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Shagimuratov, I. I.; Krankowski, A.; Ephishov, I.; Cherniak, Yu.; Wielgosz, P.; Zakharenkova, I.

    2012-06-01

    GPS measurements obtained by the global IGS network were used to study the occurrence of TEC fluctuations in the northern and southern high-latitude ionosphere during severe geomagnetic storms. In the northern hemisphere, GPS stations located higher than 55N Corrected Geomagnetic Latitude (CGL) at different longitudes were selected. In the southern hemisphere, Antarctic permanent GPS stations were used. Dual-frequency GPS measurements for individual satellite passes served as raw data. As a measure of fluctuation activity the rate of TEC (ROT) was used, and the fluctuation intensity was evaluated using the ROTI index. Using daily GPS measurements from all selected stations, images of the spatial and temporal behavior of TEC fluctuations were formed (in Corrected Geomagnetic Coordinates—CGC and geomagnetic local time—GLT). Similarly to the auroral oval, these images demonstrate an irregularity oval. The occurrence of the irregularity oval relates to the auroral oval, cusp and polar cap. During a storm, the intensity of TEC fluctuations essentially increased. The irregularity oval expands equatorward with an increase of magnetic activity. The study showed that the existing high-latitude GPS stations can provide a permanent monitoring tool for the irregularity oval in near real-time. In this paper, the features of the development of phase fluctuations at the geomagnetic conjugate points, and inter-hemispheric differences and similarities during winter and summer conditions, are discussed.

  12. Relativistic Electron Acceleration and Loss During Small Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Anderson, B.; Millan, R. M.; Reeves, G. D.; Friedel, R. H. W.

    2014-12-01

    Relativistic electron precipitation events were detected by early BARREL (Balloon Array for Radiation-belt Relativistic Electron Losses) payloads during small geomagnetic storms (minimum DST greater than -50nT), coincident with significant enhancement of relativistic electron fluxes at geosynchronous as measured by GOES. Such small geomagnetic storms have not been studied as in depth as larger storms, even though they are capable of pumping-up or depleting the radiation belts equally as extremely as their larger counterparts, this study finds. Since much of the past few years has been quiet, it is necessary to extend previous studies to include smaller storms. We perform a statistical analysis of relativistic electron flux response at geosynchronous to small geomagnetic storms over an 11 year period (1989-2000) using LANL satellite data, similar to previous studies of larger geomagnetic storms. We investigate changes in relativistic electron flux response with various solar wind parameters, as well as extend the statistical analysis of small and large geomagnetic storms with data sets now available from the Van Allen Probes.

  13. Low Latitude Pulsations Associated with Different Phases of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Bulusu, J.; Vankayala, R. C.; Sinha, A. K.; Vichare, G.; Thomas, N.

    2014-12-01

    During geomagnetic storm lot of free energy is available in the magnetosphere and this energy can act as feeder to electromagnetic waves in different frequency bands. A classical geomagnetic storm consists mainly of four phases i.e. SSC (Sudden Storm commencement), initial Phase, main phase and recovery phase. In this paper, we investigate the characteristics of electromagnetic waves in ULF (ultra low frequency) band associated with different phases of geomagnetic storms. Electromagnetic waves in ULF band (Period~ 10-100s) in the Earth's magnetosphere are generally termed as geomagnetic pulsations. A detailed statistical analysis has been performed over ten years of geomagnetic data from low latitude ground stations in Indian and Japanese sectors. The study reveals that storms in general, are accompanied with continuous pulsations of different frequency bands during different phases. In particular, the main phase of 91 % of intense storms was accompanied with pulsations in Pc5 band (frequency~ 2-7 mHz). However, the occurrence of these pulsations was less frequent during main phase of weak to moderate storms. Further, the amplitude of these pulsations increased with the intensity of storm.

  14. 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.

  15. Improving geomagnetic observatory data in the South Atlantic Anomaly

    NASA Astrophysics Data System (ADS)

    Matzka, Jürgen; Morschhauser, Achim; Brando Soares, Gabriel; Pinheiro, Katia

    2016-04-01

    The Swarm mission clearly proofs the benefit of coordinated geomagnetic measurements from a well-tailored constellation in order to recover as good as possible the contributions of the various geomagnetic field sources. A similar truth applies to geomagnetic observatories. Their scientific value can be maximised by properly arranging the position of individual observatories with respect to the geometry of the external current systems in the ionosphere and magnetosphere, with respect to regions of particular interest for secular variation, and with respect to regions of anomalous electric conductivity in the ground. Here, we report on our plans and recent efforts to upgrade geomagnetic observatories and to recover unpublished data from geomagnetic observatories at low latitudes in the South Atlantic Anomaly. In particular, we target the magnetic equator with the equatorial electrojet and low latitudes to characterise the Sq- and ring current. The observatory network that we present allows also to study the longitudinal structure of these external current systems. The South Atlantic Anomaly region is very interesting due to its secular variation. We will show newly recovered data and comparisons with existing data sets. On the technical side, we introduce low-power data loggers. In addition, we use mobile phone data transfer, which is rapidly evolving in the region and allows timely data access and quality control at remote sites that previously were not connected to the internet.

  16. Airport geomagnetic surveys in the United States

    USGS Publications Warehouse

    Berarducci, A.

    2006-01-01

    The Federal Aviation Administration (FAA) and the United States military have requirements for design, location, and construction of compass calibration pads (compass roses), these having been developed through collaboration with US Geological Survey (USGS) personnel. These requirements are detailed in the FAA Advisory Circular AC 150/5300-13, Appendix 4, and in various military documents, such as Handbook 1021/1, but the major requirement is that the range of declination measured within 75 meters of the center of a compass rose be less than or equal to 30 minutes of arc. The USGS Geomagnetism Group has developed specific methods for conducting a magnetic survey so that existing compass roses can be judged in terms of the needed standards and also that new sites can be evaluated for their suitability as potentially new compass roses. First, a preliminary survey is performed with a total-field magnetometer, with differences over the site area of less than 75nT being sufficient to warrant additional, more detailed surveying. Next, a number of survey points are established over the compass rose area and nearby, where declination is to be measured with an instrument capable of measuring declination to within 1 minute of arc, such as a Gurley transit magnetometer, DI Flux theodolite magnetometer, or Wild T-0. The data are corrected for diurnal and irregular effects of the magnetic field and declination is determined for each survey point, as well as declination range and average of the entire compass rose site. Altogether, a typical survey takes about four days to complete. ?? 2006 Springer.

  17. 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

  18. Western Disturbances: A review

    NASA Astrophysics Data System (ADS)

    Dimri, A. P.; Niyogi, D.; Barros, A. P.; Ridley, J.; Mohanty, U. C.; Yasunari, T.; Sikka, D. R.

    2015-06-01

    Cyclonic storms associated with the midlatitude Subtropical Westerly Jet (SWJ), referred to as Western Disturbances (WDs), play a critical role in the meteorology of the Indian subcontinent. WDs embedded in the southward propagating SWJ produce extreme precipitation over northern India and are further enhanced over the Himalayas due to orographic land-atmosphere interactions. During December, January, and February, WD snowfall is the dominant precipitation input to establish and sustain regional snowpack, replenishing regional water resources. Spring melt is the major source of runoff to northern Indian rivers and can be linked to important hydrologic processes from aquifer recharge to flashfloods. Understanding the dynamical structure, evolution-decay, and interaction of WDs with the Himalayas is therefore necessary to improve knowledge which has wide ranging socioeconomic implications beyond short-term disaster response including cold season agricultural activities, management of water resources, and development of vulnerability-adaptive measures. In addition, WD wintertime precipitation provides critical mass input to existing glaciers and modulates the albedo characteristics of the Himalayas and Tibetan Plateau, affecting large-scale circulation and the onset of the succeeding Indian Summer Monsoon. Assessing the impacts of climate variability and change on the Indian subcontinent requires fundamental understanding of the dynamics of WDs. In particular, projected changes in the structure of the SWJ will influence evolution-decay processes of the WDs and impact Himalayan regional water availability. This review synthesizes past research on WDs with a perspective to provide a comprehensive assessment of the state of knowledge to assist both researchers and policymakers, and context for future research.

  19. 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.

  20. Variability of ionospheric TEC during solar and geomagnetic minima (2008 and 2009): external high speed stream drivers

    NASA Astrophysics Data System (ADS)

    Verkhoglyadova, O. P.; Tsurutani, B. T.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Runge, T.

    2013-02-01

    We study solar wind-ionosphere coupling through the late declining phase/solar minimum and geomagnetic minimum phases during the last solar cycle (SC23) - 2008 and 2009. This interval was characterized by sequences of high-speed solar wind streams (HSSs). The concomitant geomagnetic response was moderate geomagnetic storms and high-intensity, long-duration continuous auroral activity (HILDCAA) events. The JPL Global Ionospheric Map (GIM) software and the GPS total electron content (TEC) database were used to calculate the vertical TEC (VTEC) and estimate daily averaged values in separate latitude and local time ranges. Our results show distinct low- and mid-latitude VTEC responses to HSSs during this interval, with the low-latitude daytime daily averaged values increasing by up to 33 TECU (annual average of ~20 TECU) near local noon (12:00 to 14:00 LT) in 2008. In 2009 during the minimum geomagnetic activity (MGA) interval, the response to HSSs was a maximum of ~30 TECU increases with a slightly lower average value than in 2008. There was a weak nighttime ionospheric response to the HSSs. A well-studied solar cycle declining phase interval, 10-22 October 2003, was analyzed for comparative purposes, with daytime low-latitude VTEC peak values of up to ~58 TECU (event average of ~55 TECU). The ionospheric VTEC changes during 2008-2009 were similar but ~60% less intense on average. There is an evidence of correlations of filtered daily averaged VTEC data with Ap index and solar wind speed. We use the infrared NO and CO2 emission data obtained with SABER on TIMED as a proxy for the radiation balance of the thermosphere. It is shown that infrared emissions increase during HSS events possibly due to increased energy input into the auroral region associated with HILDCAAs. The 2008-2009 HSS intervals were ~85% less intense than the 2003 early declining phase event, with annual averages of daily infrared NO emission power of ~ 3.3 × 1010 W and 2.7 × 1010 W in 2008 and 2009

  1. Geomagnetic Storm Main Phase effect on the Equatorial Ionosphere as measured from GPS observations at Ile-Ife

    NASA Astrophysics Data System (ADS)

    Olabode, Ayomide; Ariyibi, Emmanuel

    2016-07-01

    The effect of the main phase of two intense geomagnetic storm events which occurred on August 5-6 and September 26-27, 2011 on the equatorial ionosphere have been investigated using Global Positioning System (GPS) data obtained from an Ile-Ife station (geomagnetic lat. 9.84°N, long. 77.25°E). The WinTEC-P and GPS-TEC analysis software programs were used to process the GPS data to obtain Total Electron Content (TEC) and Scintillation Index (S4). TEC profiles during the main phase of the two geomagnetically disturbed days were compared with quiet time average profiles to examine the response of the equatorial ionosphere. International Reference Ionosphere (IRI) 2012 TEC model was also obtained from Virtual Ionosphere, Thermosphere, Mesosphere Observatory (VITMO) and the extents of deviation from measured GPS-derived TEC were examined for the main phase of the storm events. The results showed that the intensity of both storm events during the main phase which occurred at night-time correlated well with a strong southward direction of the z-component of the Interplanetary Magnetic Field (IMF-Bz) and Solar Wind Speed (Vsw), with the Disturbance storm time (Dst) profile showing multiple step development. TEC depletion was observed during the main phase of the August 5-6, 2011 storm event with TEC recording a maximum value of 9.31 TECU. A maximum TEC value of 55.8 TECU was recorded during the main phase of the September 26-27, 2011 storm event depicting TEC enhancement. Significant scintillation index value of 0.57 was observed when the main phase started on August 5-6, 2011 followed by a prolonged suppression while there was less significant scintillation impact on September 26-27, 2011 with a maximum value of 0.33. The study concluded that the intensification of the ring current during the main phase of geomagnetic storm events was responsible for the intensity of the storm events causing large variations in TEC and significant scintillation phenomenon.

  2. Applications of dispersion relations to the geomagnetic transfer function

    NASA Astrophysics Data System (ADS)

    Marcuello, A.; Queralt, P.; Ledo, J.

    2005-05-01

    The geomagnetic transfer function is nowadays used to constrain the magnetotelluric inversion procedure given that this function contains complementary information to the impedance tensor. For the models usually employed by inversions, the real and imaginary parts of the geomagnetic transfer function are related by dispersion relations. The computation of the dispersion relations involves the Hilbert transform, and here we discuss different expressions to compute them. This computation was verified using synthetically generated geomagnetic transfer function from 2D and 3D models. The dispersion relations were applied on two cases: (a) to study the consistency between the real and imaginary parts of field recorded data, and (b) to develop a procedure to complete or extend the amount of measured data.

  3. Using the moon to probe the geomagnetic tail lobe plasma

    NASA Technical Reports Server (NTRS)

    Schubert, G.; Sonett, C. P.; Smith, B. F.; Colburn, D. S.; Schwartz, K.

    1975-01-01

    We have detected the presence of plasma in the lobes of the geomagnetic tail from observations of magnetic induction in the moon forced by time variations of the earth's magnetotail lobe field. The magnitude of the moon's tangential electromagnetic transfer function when the moon is in the lobes of the geomagnetic tail is less than that when the moon is in the solar wind or geomagnetic tail plasma sheet. The tangential transfer function when the moon is in the magnetotail lobes decreases at frequencies above about 8 mHz due to finite wavelength effects. This shows that the waves in the magnetotail lobes which drive the lunar magnetic induction must have speeds far less than the speed of light and wavelengths comparable to the size of the moon.

  4. Evidence for a New Geomagnetic Jerk in 2014

    NASA Astrophysics Data System (ADS)

    Pavón-Carrasco, F. J.; Torta, J. M.; Marsal, S.; Finlay, C. C.

    2015-12-01

    The production of quasi-definitive data at an observatory has enabled us to detect a new geomagnetic jerk in 2014. The jerk has been confirmed by inspecting recent direct observations of the development of the time derivative of the field elements at several other geomagnetic observatories. Its characteristics are similar to those reported for previous jerks, though on this occasion the change in the secular variation slope in Europe almost equals that experienced at the Africa-Atlantic observatories. A global model produced with the latest available satellite and observatory data supports these findings, giving a global perspective on both the jerk and a related secular acceleration pulse at the core-mantle boundary. Should the present field variation persist, predictions from models produced with data only up until the epoch during which the jerk occurred, such as the 12th generation International Geomagnetic Reference Field, might be poorer than expected in the upcoming years.

  5. Magnetospheric mapping with a quantitative geomagnetic field model

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Mead, G. D.

    1975-01-01

    Mapping the magnetosphere on a dipole geomagnetic field model by projecting field and particle observations onto the model is described. High-latitude field lines are traced between the earth's surface and their intersection with either the equatorial plane or a cross section of the geomagnetic tail, and data from low-altitude orbiting satellites are projected along field lines to the outer magnetosphere. This procedure is analyzed, and the resultant mappings are illustrated. Extension of field lines into the geomagnetic tail and low-altitude determination of the polar cap and cusp are presented. It is noted that while there is good agreement among the various data, more particle measurements are necessary to clear up statistical uncertainties and to facilitate comparison of statistical models.

  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. The geomagnetic elements in Denmark 1928-1980

    NASA Astrophysics Data System (ADS)

    Hansen, H. A.

    Geomagnetic surveys in Denmark from 1928 till 1980 are reported. The Danish Meteorological Institute initiated a new, geomagnetic survey of Denmark in 1928 by the establishment of 10 repeat statins for observation of the geomagnetic, secular variation. The stations were visited again in 1930 and since then every fifth year. The general survey was started in 1939 and continued during the years 1946 to 1957 with the mapping of Northern Jutland. In 1967 the survey taken with a coarser spacing of the measured points during the following years succeeded in completing the mapping of the country with primary consideration to the declination. The observations on the repeat stations during the time 1928-1980 allowed development of mathematical formulas for the secular change of the magnetic elements D, H and Z at any arbitrary point in the country.

  8. Report of geomagnetic pulsation indices for space weather applications

    USGS Publications Warehouse

    Xu, Z.; Gannon, Jennifer L.; Rigler, Erin J.

    2013-01-01

    The phenomenon of ultra-low frequency geomagnetic pulsations was first observed in the ground-based measurements of the 1859 Carrington Event and has been studied for over 100 years. Pulsation frequency is considered to be “ultra” low when it is lower than the natural frequencies of the plasma, such as the ion gyrofrequency. Ultra-low frequency pulsations are considered a source of noise in some geophysical analysis techniques, such as aeromagnetic surveys and transient electromagnetics, so it is critical to develop near real-time space weather products to monitor these geomagnetic pulsations. The proper spectral analysis of magnetometer data, such as using wavelet analysis techniques, can also be important to Geomagnetically Induced Current risk assessment.

  9. Error enhancement in geomagnetic models derived from scalar data

    NASA Technical Reports Server (NTRS)

    Stern, D. P.; Bredekamp, J. H.

    1974-01-01

    Models of the main geomagnetic field are generally represented by a scalar potential gamma expanded in a finite number of spherical harmonics. Very accurate observations of F were used, but indications exist that the accuracy of models derived from them is considerably lower. One problem is that F does not always characterize gamma uniquely. It is not clear whether such ambiguity can be encountered in deriving gamma from F in geomagnetic surveys, but there exists a connection, due to the fact that the counterexamples of Backus are related to the dipole field, while the geomagnetic field is dominated by its dipole component. If the models are recovered with a finite error (i.e. they cannot completely fit the data and consequently have a small spurious component), this connection allows the error in certain sequences of harmonic terms in gamma to be enhanced without unduly large effects on the fit of F to the model.

  10. Semiannual variation of the geomagnetic activity and solar wind parameters

    NASA Astrophysics Data System (ADS)

    Orlando, M.; Moreno, G.; Parisi, M.; Storini, M.

    1993-10-01

    The semiannual variation of the geomagnetic activity is investigated in connection with a large set of solar wind and interplanetary magnetic field data (4494 daily averages from 1965 to 1987). Our analysis confirms that the geomagnetic activity (described by the aa index), is mainly modulated by the southward component of the magnetic field (BS), as suggested by Russell and McPherron. On the other hand, it is also found that the solar wind velocity (V) has a relevant role in this phenomenon. In fact, the amplitude of the aa modulation is best correlated with the function BSV2. We also explore the linkage between the annual trend of aa and the sunspot activity (1868-1989), showing that the modulation of the geomagnetic activity follows a more regular pattern during the descending phase of the solar cycle than during the rising and maximum parts.

  11. Equatorial Ionospheric Irregularities Observed in the South American Sector During the December 2006 Geomagnetic Storm

    NASA Astrophysics Data System (ADS)

    Sahai, Y.; de Jesus, R.; Guarnieri, F. L.; Fagundes, P. R.; de Abreu, A. J.; Becker-Guedes, F.; Abalde, J. R.; Brunini, C.; Gende, M.; Cintra, T.; de Souza, V.; Pillat, V.; Lima, W.

    2009-05-01

    This investigation presents studies related to the observations of equatorial ionospheric irregularities in the ionospheric F-region in the South American sector during the intense geomagnetic storm in December 2006, during the period of low solar activity. The geomagnetic storm reached a minimum Dst of -147 nT at 0700 UT on 15 December. In this work ionospheric sounding data obtained between 13 and 16 December 2006 at Palmas (PAL; 10.2o S, 48.2o W; dip latitude 6.6o S) and São José dos Campos (SJC, 23.2o S, 45.9o W; dip latitude 17.6o S), Brazil, and Jicamarca (JIC, 12.0o S, 76.8o W; dip latitude 0.05o S), Peru, have been used. Also, vertical total electron content (VTEC) and phase fluctuations (TECU/min) from GPS observations obtained at Brasilia (BRAZ, 15.9o S, 47.9o W; dip latitude 11.7o S), Presidente Prudente (PPTE, 22.12° S, 51.4° W; dip latitude 14,9° S), Curitiba (PARA, 25.43o S, 49.21o W; dip latitude 18.4o S), Santa Maria (SMAR, 29.71o S, 53.07o W; dip latitude 19.6o S), Brazil, Bahia Blanca (VBCA, 38.7o S, 62.3o W; dip latitude 22.4o S) and Puerto Deseado (PDES, 47.7o S, 65.9o W, dip latitude 27.1o S), Argentina, during the period 13 to 16 December are presented. An unusual uplifting of the F-region during pre-reversal enhancement (PRE) on 14 December was possibly associated with a prompt penetration of electric field of magnetospheric origin after the storm sudden commencement (1414 UT on 14 December). On this geomagnetically disturbed night of 14-15 December, intense equatorial ionospheric irregularities were observed up to southern most GPS station PDES in Argentina. It should be mentioned that on the other nights viz., 12-13 and 13-14 December (both nights before the storm), and 15-16 December (recovery phase), the ionospheric irregularities are limited to only the Brazilian GPS stations. On the geomagnetically disturbed night of 14-15 December, strong oscillations were observed in the F-region base height possibly associated with Joule heating

  12. The solar wind-magnetosphere energy coupling and magnetospheric disturbances

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1980-01-01

    Energy coupling between the solar wind and the magnetosphere is examined and the influence of this coupling on magnetospheric disturbances is discussed. Following a review of the components of the total energy production rate of the magnetosphere and progress in the study of solar wind-magnetosphere correlations, the derivation of the solar wind-magnetosphere energy coupling function, which has been found to correlate well with the total magnetospheric energy production rate, is presented. Examination of the relations between the energy coupling function and the type of magnetic disturbance with which it is associated indicates that magnetic storms with a large sudden storm commencement and a weak main phase are associated with small energy coupling, while values of the coupling function greater than 5 x 10 to the 18th to 10 to the 19th erg/sec are required for the development of a major geomagnetic storm. The magnetospheric substorm is shown to be a direct result of increased solar wind-magnetosphere energy coupling rather than the sudden conversion of stored magnetic energy. Finally, it is indicated that at energy couplings greater than 10 to the 19th erg/sec, the positive feedback process responsible for substorms breaks down, resulting in the abnormal growth of the ring current.

  13. Geomagnetic inverse problem and data assimilation: a progress report

    NASA Astrophysics Data System (ADS)

    Aubert, Julien; Fournier, Alexandre

    2013-04-01

    In this presentation I will present two studies recently undertaken by our group in an effort to bring the benefits of data assimilation to the study of Earth's magnetic field and the dynamics of its liquid iron core, where the geodynamo operates. In a first part I will focus on the geomagnetic inverse problem, which attempts to recover the fluid flow in the core from the temporal variation of the magnetic field (known as the secular variation). Geomagnetic data can be downward continued from the surface of the Earth down to the core-mantle boundary, but not further below, since the core is an electrical conductor. Historically, solutions to the geomagnetic inverse problem in such a sparsely observed system were thus found only for flow immediately below the core mantle boundary. We have recently shown that combining a numerical model of the geodynamo together with magnetic observations, through the use of Kalman filtering, now allows to present solutions for flow throughout the core. In a second part, I will present synthetic tests of sequential geomagnetic data assimilation aiming at evaluating the range at which the future of the geodynamo can be predicted, and our corresponding prospects to refine the current geomagnetic predictions. Fournier, Aubert, Thébault: Inference on core surface flow from observations and 3-D dynamo modelling, Geophys. J. Int. 186, 118-136, 2011, doi: 10.1111/j.1365-246X.2011.05037.x Aubert, Fournier: Inferring internal properties of Earth's core dynamics and their evolution from surface observations and a numerical geodynamo model, Nonlinear Proc. Geoph. 18, 657-674, 2011, doi:10.5194/npg-18-657-2011 Aubert: Flow throughout the Earth's core inverted from geomagnetic observations and numerical dynamo models, Geophys. J. Int., 2012, doi: 10.1093/gji/ggs051

  14. Geomagnetic, cosmogenic and climatic changes across the last geomagnetic reversal from Equatorial Indian Ocean sediments

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Bassinot, Franck; Bouilloux, Alexandra; Bourlès, Didier; Nomade, Sébastien; Guillou, Valéry; Lopes, Fernand; Thouveny, Nicolas; Dewilde, Fabien

    2014-07-01

    distribution of tektite abundance was used to deconvolve the 10Be/9Be signal. The results confirm that the beryllium changes are concentrated during the transitional period, thus likely in presence of a multipolar geomagnetic field (or in the vicinity of a geomagnetic pole) that favored the penetration of cosmic rays and consequently increased the 10Be production. The absence of 10Be during the precursor indicates that the present site and the Indonesian ones were far away from a geomagnetic pole and that interlatitudinal atmospheric mixing was limited. The geomagnetic pole positions above the Indonesian sites during the precursor would thus be incompatible with the corresponding inclined dipolar field during this period, and suggest the dominance of low-degree harmonics.

  15. GEOMAGNETIC REVERSALS DRIVEN BY ABRUPT SEA LEVEL CHANGES

    SciTech Connect

    Muller, R.A.; Morris, D.E.

    1986-10-01

    Changes in the moment of inertia of the earth, brought about by the redistribution of ocean water from the tropics to ice at high latitudes, couple energy from the spin of the earth into convection in the liquid core. This mechanism may help provide the driving energy for the earth's dynamo. Sufficiently rapid ocean level changes can disrupt the dynamo, resulting (in half of the cases) in a geomagnetic field reversal. The model can account for the previously mysterious correlation reported between geomagnetic reversals and mass extinctions.

  16. Effects of a geomagnetic storm on thermospheric circulation. Master's thesis

    SciTech Connect

    Brinkman, D.G.

    1987-01-01

    The motions of the thermosphere and its interactions with the ionosphere during a geomagnetic storm are of current interest to space scientists. A two-dimensional model was used to simulate the thermospheric response to the impulsive high-latitude heating associated with a geomagnetic storm. The storm-induced motions can be characterized by an initial period of transient waves followed by the development of a mean circulation. These motions generate an electrical-current system that is on the same order of magnitude as, and in the opposite sense to the normal s/sub q/ current system. Model-simulated winds and electrical currents were then compared to observations.

  17. 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.

  18. Modeling Thermospheric Dynamics Under all Solar, Geomagnetic, and Lower Atmosphere Conditions

    NASA Astrophysics Data System (ADS)

    Fuller-Rowell, T. J.; Fedrizzi, M.; Fang, T. W.; Codrescu, M.; Negrea, C.; Lu, X.; Wu, F.

    2014-12-01

    During very active geomagnetic conditions, neutral thermospheric dynamics is dominated by magnetospheric momentum and energy input. Mid and high latitude horizontal winds can exceed many hundreds of meters per second, vertical winds many tens of meters per second, and the impulsive energy input can drive global wave surges of one to two hundred meters per second. The latitudinal change in global temperature and pressure from the energy input drives an altered circulation, neutral composition structure, and the disturbance dynamo, all of which have dramatic impact on the ionosphere. During more typical solar and geomagnetic activity conditions the balance between these solar and magnetospheric drivers, and forcing from the lower atmosphere, is not so clear. A whole spectrum of waves, including migrating and non-migrating tides and gravity waves, propagate from sources in the lower atmosphere, increase in amplitude, and drive winds throughout the thermosphere and at all latitudes. Some of these waves break in the mesosphere and lower thermosphere and mix the constituents. Some penetrate further into the thermosphere driving steep vertical gradients, and as they dissipate by molecular viscosity they deposit momentum. Much of the variability in electrodynamics is driven by the larger-scale tidal spectrum of waves driving neutral winds in the lower thermosphere dynamo region. The shorter period and smaller scale spectrum of gravity waves also drive neutral winds, and their impact is readily apparent in the ionosphere from incoherent scatter and dynasonde observations. The still sparse direct observations of neutral winds means that sometimes it is the impact on the ionosphere that must be used to indicate the presence of neutral atmospheric winds and waves.

  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. Quantitative maps of geomagnetic perturbation vectors during substorm onset and recovery

    PubMed Central

    Pothier, N M; Weimer, D R; Moore, W B

    2015-01-01

    We have produced the first series of spherical harmonic, numerical maps of the time-dependent surface perturbations in the Earth's magnetic field following the onset of substorms. Data from 124 ground magnetometer stations in the Northern Hemisphere at geomagnetic latitudes above 33° were used. Ground station data averaged over 5 min intervals covering 8 years (1998–2005) were used to construct pseudo auroral upper, auroral lower, and auroral electrojet (AU*, AL*, and AE*) indices. These indices were used to generate a list of substorms that extended from 1998 to 2005, through a combination of automated processing and visual checks. Events were sorted by interplanetary magnetic field (IMF) orientation (at the Advanced Composition Explorer (ACE) satellite), dipole tilt angle, and substorm magnitude. Within each category, the events were aligned on substorm onset. A spherical cap harmonic analysis was used to obtain a least error fit of the substorm disturbance patterns at 5 min intervals up to 90 min after onset. The fits obtained at onset time were subtracted from all subsequent fits, for each group of substorm events. Maps of the three vector components of the averaged magnetic perturbations were constructed to show the effects of substorm currents. These maps are produced for several specific ranges of values for the peak |AL*| index, IMF orientation, and dipole tilt angle. We demonstrate an influence of the dipole tilt angle on the response to substorms. Our results indicate that there are downward currents poleward and upward currents just equatorward of the peak in the substorms' westward electrojet. Key Points Show quantitative maps of ground geomagnetic perturbations due to substorms Three vector components mapped as function of time during onset and recovery Compare/contrast results for different tilt angle and sign of IMF Y-component PMID:26167445

  1. Comparison of Ionospheric TEC Derived from GPS and IRI 2012 Model during Geomagnetic Storms at Indonesia

    NASA Astrophysics Data System (ADS)

    Marlia, Dessi; Wu, Falin

    2016-07-01

    This paper investigates the variations of vertical Total Electron Content (VTEC) at Manado, Indonesia (geographic coordinates : lat 1.34 ° S and long 124.82 ° E) for period 2013. The GPS measured TEC is compared with the TEC derived from the IRI (International Reference Ionosphere) 2012 model. Vertical TEC measurements obtained from dual frequency GPS receiver that is GISTM (GPS Ionospheric Scintillations and TEC monitor). Variation of TEC validate to IRI 2012 model at Manado station has been compared with the model for three different topside of electron density namely NeQuick, IRI-01-Corr and IRI2001.There is a need to investigation on diurnal, seasonal variations, solar activity dependence of TEC and including effects of space weather related events to TEC and modeling of TEC. In this paper, diurnal and seasonal variations of VTEC and the effect of VTEC due to space weather events like Geomagnetic storms are analyzed. The result show that the TEC prediction using IRI-2001 model overestimated the GPS TEC measurements, while IRI-NeQuick and IRI-01-corr show a tendency to underestimates the observed TEC during the day time particularly in low latitude region in the maximum solar activity period (2013). The variations of VTEC during 17th March, 2013, 29th June, 2013 storms are analyzed. During 17th March,2013 storm enhancement in VTEC with Kp value 6 and Disturbance storm index (DST) -132 nT. During 29th June, 2013 storm VTEC depletion with value 7 and DST -98 nT. Significant deviations in VTEC during the main phase of the storms are observed. It is found that the response of ionospheric TEC consist of effects of both enhancement and depletions in ionospheric structures (positive and negative storm). Keywords: TEC ionosphere, GPS, GISTM, IRI 2012 model, solar activity, geomagnetic storm

  2. Sediments fail to record geomagnetic transitions

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Meynadier, Laure; Bassinot, Franck; Simon, Quentin; Thouveny, Nicolas

    2016-04-01

    consequence the VGPs follow a simple longitudinal trajectory like expected for a rotation of the dipole. This unrealistic scenario likely results from heavy post-depositional processes that integrated various amounts of pre- and post-transitional magnetic directions within each sample. These results confirm that sediments are mostly inappropriate to extract suitable information about geomagnetic reversals.

  3. Prediction of Geomagnetic Storm Strength from Inner Heliospheric In Situ Observations

    NASA Astrophysics Data System (ADS)

    Kubicka, M.; Moestl, C.; Rollett, T.; Feng, L.; Eastwood, J. P.; Boakes, P. D.

    2015-12-01

    In order to predict the effects of interplanetary coronal mass ejections (ICMEs) on Earth, it is important to know the properties of the interplanetary magnetic field (IMF). Of special interest is the southward component (Bz) of the IMF, acting as a main driver for geomagnetic storms. We are working on a proof-of-concept for predicting the strength of geomagnetic storms caused by ICMEs by using in situ data from spacecraft in the inner heliosphere. Our prediction includes the arrival time and speed of the ICME at Earth, the IMF's Bz component and the resulting disturbance storm time index (Dst), which is a prime indicator of geomagnetic activity. For Dst forecasting, the two well established models Burton et al. (1975) and O'Brien & McPherron (2000) are used. Necessary parameters for those models are the ICME speed and the Bz component of the IMF at 1 AU. We obtain the ICME speed using a drag-based model, and the IMF's Bz component is predicted based on a power law from the in situ data. Additionally, the ENLIL/WSA model provides the solar wind background speed for the drag-based model.An advantage of our method is the use of the in situ spacecraft as a reference point for the drag based-model, leading to a more precise arrival speed of the ICME at Earth, and an improved arrival time. Investigation of an ICME in June 2012 shows already very promising results for the Dst index, as well as for the ICME arrival speed. The main advantage of this method is the prediction lead time of ~21 hours compared to only ~40-60 minutes, using an L1 located spacecraft. Furthermore, the feasibility of this method can be studied with any in situ spacecraft temporarily located between the Sun and Earth, like Helios, Solar Orbiter or Solar Probe Plus, and also works for radial spacecraft alignments. The techniques we develop could be routinely applied to a mission that forms an artificial Lagrange point along the Sun-Earth line, e.g. for a Sunjammer or Heliostorm mission.

  4. Density duct formation in the wake of a travelling ionospheric disturbance: Murchison Widefield Array observations

    NASA Astrophysics Data System (ADS)

    Loi, Shyeh Tjing; Cairns, Iver H.; Murphy, Tara; Erickson, Philip J.; Bell, Martin E.; Rowlinson, Antonia; Arora, Balwinder Singh; Morgan, John; Ekers, Ronald D.; Hurley-Walker, Natasha; Kaplan, David L.

    2016-02-01

    Geomagnetically aligned density structures with a range of sizes exist in the near-Earth plasma environment, including 10-100 km wide VLF/HF wave-ducting structures. Their small diameters and modest density enhancements make them difficult to observe, and there is limited evidence for any of the several formation mechanisms proposed to date. We present a case study of an event on 26 August 2014 where a travelling ionospheric disturbance (TID) shortly precedes the formation of a complex collection of field-aligned ducts, using data obtained by the Murchison Widefield Array (MWA) radio telescope. Their spatiotemporal proximity leads us to suggest a causal interpretation. Geomagnetic conditions were quiet at the time, and no obvious triggers were noted. Growth of the structures proceeds rapidly, within 0.5 h of the passage of the TID, attaining their peak prominence 1-2 h later and persisting for several more hours until observations ended at local dawn. Analyses of the next 2 days show field-aligned structures to be preferentially detectable under quiet rather than active geomagnetic conditions. We used a raster scanning strategy facilitated by the speed of electronic beamforming to expand the quasi-instantaneous field of view of the MWA by a factor of 3. These observations represent the broadest angular coverage of the ionosphere by a radio telescope to date.

  5. Disturbance regime and disturbance interactions in Rocky Mountain subalpine forest

    USGS Publications Warehouse

    Veblen, Thomas T.; Hadley, Keith S.; Nel, Elizabeth M.; Kitzberger, Thomas; Reid, Marion; Villalba, Ricardo

    1994-01-01

    1 The spatial and temporal patterns of fire, snow avalanches and spruce beetle out-breaks were investigated in Marvine Lakes Valley in the Colorado Rocky Mountains in forests of Picea engelmannii, Abies lasiocarpa, Pseudotsuga menziesiiand Populus tremuloides. Dates and locations of disturbances were determined by dendrochronological techniques. A geographic information system (GIS) was used to calculate areas affected by the different disturbance agents and to examine the spatial relationships of the different disturbances. 2 In the Marvine Lakes Valley, major disturbance was caused by fire in the 1470s, the 1630s and the 1870s and by spruce beetle outbreak in c. 1716, 1827 and 1949. 3 Since c. 1633, 9% of the Marvine Lakes Valley has been affected by snow avalanches, 38.6% by spruce beetle outbreak and 59.1% by fire. At sites susceptible to avalanches, avalanches occur at a near-annual frequency. The mean return intervals for fire and spruce beetle outbreaks are 202 and 116.5 years, respectively. Turnover times for fire and spruce beetle outbreaks are 521 and 259 years, respectively. 4 Several types of disturbance interaction were identified. For example, large and severe snow avalanches influence the spread of fire. Similarly, following a stand-devastating fire or avalanche, Picea populations will not support a spruce beetle outbreak until individual trees reach a minimum diameter which represents at least 70 years' growth. Thus, recent fires and beetle outbreaks have nonoverlapping distributions.

  6. 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.

  7. First results from the first Croatian geomagnetic observatory

    NASA Astrophysics Data System (ADS)

    Mandic, Igor; Herak, Davorka; Heilig, Balazs

    2013-04-01

    The first Croatian geomagnetic observatory was established in the area of the Nature Park Lonjsko Polje, after a century of sporadic efforts originating from the proposals of Andrija Mohorovicic. The location was chosen after exhaustive surveys of possible sites. It is located far enough from sources of civilization noise, and was found to be an area without magnetic anomalies and with a low field gradient. The construction of the observatory buildings was completed in the autumn of 2011. The furnishing and installation of instruments and test measurements were completed by the beginning of summer 2012, ever since we have continuous recordings of the geomagnetic elements. In the beginning of December 2012 the fluxgate magnetometer LEMI-035 (H,D,Z orientation) has been installed under the framework of the PLASMON project in cooperation with the Tihany Observatory (Hungary). Permanent data of high quality from our observatory will contribute to the monitoring of the Earth's magnetic field on the regional and global levels, thus enabling further development of geomagnetism in Croatia through collaboration with scientists from the other countries, participation in the international projects, eventual membership in the International Real-time Magnetic Observatory Network (INTERMAGNET), etc. The field elements for the epoch 2012,75 and the baselines are presented together with highlights of some recorded geomagnetic events so far. Furthermore, the comparison between the variation data recorded by the dIdD and the fluxgate LEMI-035 magnetometer is presented.

  8. Particle acceleration from reconnection in the geomagnetic tail

    SciTech Connect

    Birn, J.; Borovsky, J.E.; Thomsen, M.F.; McComas, D.J.; Reeves, G.D.; Belian, R.D.; Hesse, M.; Schindler, K.

    1997-08-01

    Acceleration of charged particles in the near geomagnetic tail, associated with a dynamic magnetic reconnection process, was investigated by a combined effort of data analysis, using Los Alamos data from geosynchronous orbit, MHD modeling of the dynamic evolution of the magnetotail, and test particle tracing in the electric and magnetic fields obtained from the MHD simulation.

  9. 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).

  10. Interplanetary field and plasma during initial phase of geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Patel, V. L.; Wiskerchen, M. J.

    1975-01-01

    Twenty-three geomagnetic storm events during 1966 to 1970 were studied by using simultaneous interplanetary magnetic field and plasma parameters. Explorer 33 and 35 field and plasma data were analyzed on large-scale (hourly) and small-scale (3 min.) during the time interval coincident with the initial phase of the geomagnetic storms. The solar-ecliptic Bz component turns southward at the end of the initial phase, thus triggering the main phase decrease in Dst geomagnetic field. The By component also shows large fluctuations along with Bz. When there are no clear changes in the Bz component, the By shows abrupt changes at the main phase onset. On the small-scale, behavior of the magnetic field and electric field were studied in detail for the three events; it is found that the field fluctuations in By, Bz and Ey and Ez are present in the initial phase. In the large-scale, the behavior field remains quiet because the small-scale variations are averaged out. It appears that large as well as small time scale fluctuations in the interplanetary field and plasma help to alter the internal electromagnetic state of the magnetosphere so that a ring current could causing a geomagnetic storm decrease.

  11. Permutation Entropy Analysis of Geomagnetic Indices Time Series

    NASA Astrophysics Data System (ADS)

    De Michelis, Paola; Consolini, Giuseppe

    2013-04-01

    The Earth's magnetospheric dynamics displays a very complex nature in response to solar wind changes as widely documented in the scientific literature. This complex dynamics manifests in various physical processes occurring in different regions of the Earth's magnetosphere as clearly revealed by previous analyses on geomagnetic indices (AE-indices, Dst, Sym-H, ....., etc.). One of the most interesting features of the geomagnetic indices as proxies of the Earth's magnetospheric dynamics is the multifractional nature of the time series of such indices. This aspect has been interpreted as the occurrence of intermittence and dynamical phase transition in the Earth's magnetosphere. Here, we investigate the Markovian nature of different geomagnetic indices (AE-indices, Sym-H, Asy-H) and their fluctuations by means of Permutation Entropy Analysis. The results clearly show the non-Markovian and different nature of the distinct sets of geomagnetic indices, pointing towards diverse underlying physical processes. A discussion in connection with the nature of the physical processes responsible of each set of indices and their multifractional character is attempted.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

    2011-10-01

    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.

  14. Geomagnetic Variations and Their Possible Effects on System Earth

    NASA Astrophysics Data System (ADS)

    Glassmeier, K.

    2003-12-01

    The Earth magnetic field exhibits a variety of temporal variations with time scales ranging from a few seconds up to millions of years. The most pronounced variation is certainly a polarity transition during which the geomagnetic field strength decays down to about 10-20 % of its current value. A question of immediate interest is whether and in which way System Earth reacts on such a dramatic event. First the magnetosphere changes its size and shape. Due to the decreasing geomagnetic field the magnetopause is located much closer to the surface of the Earth. If the field exhibits strong quadrupole components magnetic reconnection can happen in the northern dayside magnetosphere with the southern hemisphere featuring a closed magnetosphere. Also the magnetotail structure changes drastically. Energetic particle entry occurs not only in dipolar cap regions but over much enlarged areas. As the ionospheric conductivity depends on the geomagnetic field strength first estimates furthermore indicate that externally driven geomagnetic variations are stronger during times of a polarity transition. The weaker field also makes the middle atmosphere much more sensitive to energetic particle events and large natural ozone holes are very likely during polarity transitions as first model calculations indicate.

  15. Geomagnetic cutoffs: a review for space dosimetry applications.

    PubMed

    Smart, D F; Shea, M A

    1994-10-01

    The earth's magnetic field acts as a shield against charged particle radiation from interplanetary space, technically described as the geomagnetic cutoff. The cutoff rigidity problem (except for the dipole special case) has "no solution in closed form". The dipole case yields the Stormer equation which has been repeatedly applied to the earth in hopes of providing useful approximations of cutoff rigidities. Unfortunately the earth's magnetic field has significant deviations from dipole geometry, and the Stormer cutoffs are not adequate for most applications. By application of massive digital computer power it is possible to determine realistic geomagnetic cutoffs derived from high order simulation of the geomagnetic field. Using this technique, "world-grids" of directional cutoffs for the earth's surface and for a limited number of satellite altitudes have been derived. However, this approach is so expensive and time consuming it is impractical for most spacecraft orbits, and approximations must be used. The world grids of cutoff rigidities are extensively used as lookup tables, normalization points and interpolation aids to estimate the effective geomagnetic cutoff rigidity of a specific location in space. We review the various options for estimating the cutoff rigidity for earth-orbiting satellites. PMID:11540027

  16. ISS Plasma Contactor Units Operations During Strong Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Alred, J.; Mikatarian, R.; Barsamian, H.; Minow, J.; Koontz, S.

    2003-12-01

    The large structure and high voltage arrays of the ISS represent a complex system that interacts with the Earth's ionosphere. To mitigate spacecraft charging problems on the ISS, two Plasma Contactor Units discharge ionized xenon gas to "clamp" the potential of the ISS with respect to the low Earth orbit plasma. The Plasma Interaction Model, a model of ISS plasma interaction developed from the basic physics of the interaction phenomena, includes magnetic induction effects, plasma temperature and density effects, interaction of the high voltage solar arrays with ionospheric plasma, and accounts for other conductive areas on the ISS. To augment this model, the PCU discharge current has been monitored for the ISS in a variety of flight attitudes as well as during the annual seasons. A review of the PCU discharge currents shows a correlation to the geomagnetic activity. The variation in the PCU discharge current during strong geomagnetic activity will be presented. Also, the PCU discharge currents during periods of low geomagnetic activity will be discussed. The presentation will conclude with a comparison of satellite plasma measurements during different stages of geomagnetic activity.

  17. (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.

  18. The prolonged southward IMF-Bz event of 2-4 May 1998: Solar, interplanetary causes and geomagnetic consequences

    NASA Astrophysics Data System (ADS)

    Bisoi, Susanta Kumar; Chakrabarty, D.; Janardhan, P.; Rastogi, R. G.; Yoshikawa, A.; Fujiki, K.; Tokumaru, M.; Yan, Y.

    2016-05-01

    A detailed investigation is carried out to understand the prolonged (˜44 h) weakly southward interplanetary magnetic field (IMF-Bz) condition during 2-4 May 1998. In situ observations, during the period, show the passage of an expanding magnetic cloud embedded in an interplanetary coronal mass ejection (ICME), followed up by a shock and an interplanetary discontinuity driven by another ICME. It is the arrival of the ICMEs and the upfront shocks that caused the prolonged southward IMF-Bz condition. The magnetic configuration of the source regions of the IMF associated with the ICME interval was also examined, which showed open magnetic field structures, emanating from a small active region on the north of the heliospheric current sheet (HCS). The structures remained constantly to the north of the HCS, both on 29 April and 1 May, suggesting no change in their polarity. The draping of these outward directed radial field lines around the propagating CMEs in the shocked plasma explains the observed polarity changes of the IMF-Bz at 1 AU. In addition, multiple enhancements were also detected in the geomagnetic field variations, which showed a distinct one-to-one correspondence with the density pulses observed at 1 AU, during 0700-1700 UT on 3 May. The spectral analyses of both the variations showed the same discrete frequencies of 0.48, 0.65, and 0.75 mHz, demonstrating that the solar wind density enhancements can cause detectable global geomagnetic disturbances. The observations, thus, provide a deeper insight into the possible causes and geomagnetic consequences of a prolonged weakly southward IMF-Bz condition.

  19. 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

  20. An investigation of ionospheric F region response in the Brazilian sector to the super geomagnetic storm of May 2005

    NASA Astrophysics Data System (ADS)

    de Abreu, A. J.; Sahai, Y.; Fagundes, P. R.; de Jesus, R.; Bittencourt, J. A.; Pillat, V. G.

    2011-10-01

    In this paper, we have investigated the responses of the ionospheric F region at equatorial and low latitude regions in the Brazilian sector during the super geomagnetic storm on 15-16 May 2005. The geomagnetic storm reached a minimum Dst of -263 nT at 0900 UT on 15 May. In this paper, we present vertical total electron content (vTEC) and phase fluctuations (in TECU/min) from Global Positioning System (GPS) observations obtained at Belém, Brasília, Presidente Prudente, and Porto Alegre, Brazil, during the period 14-17 May 2005. Also, we present ionospheric parameters h'F, hpF2, and foF2, using the Canadian Advanced Digital Ionosonde (CADI) obtained at Palmas and São José dos Campos, Brazil, for the same period. The super geomagnetic storm has fast decrease in the Dst index soon after SSC at 0239 UT on 15 May. It is a good possibility of prompt penetration of electric field of magnetospheric origin resulting in uplifting of the F region. The vTEC observations show a trough at BELE and a crest above UEPP, soon after SSC, indicating strengthening of nighttime equatorial anomaly. During the daytime on 15 and 16 May, in the recovery phase, the variations in foF2 at SJC and the vTEC observations, particularly at BRAZ, UEPP, and POAL, show large positive ionospheric storm. There is ESF on the all nights at PAL, in the post-midnight (UT) sector, and phase fluctuations only on the night of 14-15 May at BRAZ, after the SSC. No phase fluctuations are observed at the equatorial station BELE and low latitude stations (BRAZ, UEPP, and POAL) at all other times. This indicates that the plasma bubbles are generated and confined on this magnetically disturbed night only up to the low magnetic latitude and drifted possibly to west.

  1. [Seasonal variations in the myocardial infarction incidence and possible effects of geomagnetic micropulsations on the cardiovascular system in humans].

    PubMed

    Kleĭmenova, N G; Kozyreva, O V; Breus, T K; Rapoport, S I

    2007-01-01

    The analysis of the ambulance calls in Moscow, related to myocardial infarction (85.000 events), sudden death (71.700 events), and hypertension crises (165.500 events) over the period of 1979-1981 demonstrated their clear seasonal variations with a profound summer minimum and a winter maximum. The same results were obtained in the analysis of statistical monthly data on sudden death from infarction in Bulgaria over the period of 15 years (1970-1985). However, there are a great number of clinical and statistical studies confirming the rises in the incidence of myocardial infarction, hypertension crise, and sudden death during geomagnetic disturbances, which have maximum occurrence near equinox, not in winter. In order to explain this contradiction, we suggested that one of critical factors that affect the human cardiovascular system is geomagnetic micropulsations Pc1 having the frequency comparable with the frequency of heart rate beatings and winter maximum in their occurrence. The results of a comparative analysis of data of ambulance calls in Moscow related to myocardial infarction and sudden death and the catalog of Pc1 observations at the geophysical observatory "Borok" (Yaroslavl region) are presented. It is shown that in approximately 70% of days with an anomalously large number of ambulance calls related to myocardial infarction, Pc1 micropulsations have been registered. The probability of simultaneous occurrence of myocardial infarction and Pc1 in the winter season was 1.5 times greater than their accidental coincidence. Moreover, it was found that in winter the effects of magnetic storms and Pc1 IM(A) were much higher than in summer. We suggested that one of possible reasons for the seasonal variations in the occurrence of myocardial infarction is an increase in the production of the pineal hormone melatonin in winter which leads to an unstable state of the human organism and an increase in its sensitivity to the effect of geomagnetic pulsations. PMID

  2. Geomagnetic-pulsation studies using the AFGL Magnetometer Network. Final Report, 1 Dec 1983-28 February 1987

    SciTech Connect

    Hughes, W.J.

    1987-06-01

    This contract funded a study of geomagnetic pulsations, the lowest-frequency waves that occur naturally in the Earth's magnetosphere. The study used as its primary data source the AFGL Magnetometer Network, which recorded midlatitude and subauroral magnetic variations continuously for six years. The major aim of the study was to develop Pi2 pulsations which occur at substorm onset, as monitors and locators of magnetospheric activity. Other aims of the study were to study the higher-frequency types of continuous pulsation, which are believed to be generated via ion-cyclotron resonance in the radiation belt, and to develop data management and analysis software. These latter aims were in preparation for the upcoming CRRES mission. The midlatitude Pi2's are in a reliable indicator of substorms and their polarization pattern provides a good method of finding the local time of the main activity of a particular substorm. For small isolated substorms the center of the polarization pattern and the center of the midlatitude geomagnetic bay pattern produce by the dc substorm currents, coincide, but during more disturbed intervals this is not always true, as consecutive bays are not well separated from one another. The midlatitude signatures spatially relate the other various signatures of substorm onset seen at geosynchronous orbit and in the auroral zone. The main auroral surge forms about an hour west of the center of the Pi2 polarization pattern and the longitude at which the surge forms separates the region of space near geosynchronous orbit where the geomagnetic field becomes more dipolar from that where it becomes more taillike.

  3. On the Possibilities of Predicting Geomagnetic Secular Variation with Geodynamo Modeling

    NASA Technical Reports Server (NTRS)

    Kuang, Wei-Jia; Tangborn, Andrew; Sabaka, Terrance

    2004-01-01

    We use our MoSST core dynamics model and geomagnetic field at the core-mantle boundary (CMB) continued downward from surface observations to investigate possibilities of geomagnetic data assimilation, so that model results and current geomagnetic observations can be used to predict geomagnetic secular variation in future. As the first attempt, we apply data insertion technique to examine evolution of the model solution that is modified by geomagnetic input. Our study demonstrate that, with a single data insertion, large-scale poloidal magnetic field obtained from subsequent numerical simulation evolves similarly to the observed geomagnetic variation, regardless of the initial choice of the model solution (so long it is a well developed numerical solution). The model solution diverges on the time scales on the order of 60 years, similar to the time scales of the torsional oscillations in the Earth's core. Our numerical test shows that geomagnetic data assimilation is promising with our MoSST model.

  4. Empirical evidence for latitude dependence and asymmetry of geomagnetic spatial variation in mainland China

    NASA Astrophysics Data System (ADS)

    Lu, Shikun; Zhang, Hao; Li, Xihai; Liu, Daizhi; Wang, Xiqin

    2016-05-01

    Spatiotemporal geomagnetic variation is a significant research topic of geomagnetism and space physics. Generated by convection and flows within the fluid outer core, latitude dependence and asymmetry, as the inherent spatiotemporal properties of geomagnetic field, have been extensively studied. We apply and modify an extension of existing method, Hidden Markov Model (HMM), which is an efficient tool for modeling the statistical properties of time series. Based on ground magnetic measurement data set in mainland China, first, we find the parameters of HMM can be used as the geomagnetic statistical signature to represent the spatiotemporal geomagnetic variations for each site. The results also support the existence of the geomagnetic latitude dependence more apparently. Furthermore, we provide solid empirical evidence for geomagnetic asymmetry relying on such ground magnetic measurement data set.

  5. 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

  6. 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.

  7. The response of local power grid at low-latitude to geomagnetic storm: An application of the Hilbert Huang transform

    NASA Astrophysics Data System (ADS)

    Liu, Jin; Wang, Chuan-Bing; Liu, Lu; Sun, Wei-Huai

    2016-04-01

    The Hilbert-Huang transform (HHT) is an adaptive data analysis method that can accommodate the variety of data generated by nonlinear and nonstationary processes in nature. In this paper, we focus on the small geomagnetically induced current (GIC) at the local substations in low-latitude power grid of China, responding to a moderate storm on 14-18 July 2012. The HHT is applied to analyze the neutral point currents (NPCs) of transformers measured at different substations, and the GIC indices converted from local geomagnetic field measurements. The original data are decomposed into intrinsic mode functions (IMFs) using the ensemble empirical mode decomposition. After removal of the quasi-diurnal components related with the solar quiet variation, the IMFs representing storm disturbances are transformed into Hilbert energy spectra. The results show that some transformers have more or less responses to the moderate storm in the form of Hilbert energy spectra with the frequency around 2-3 mHz. A comparison on the amplitude changes of the spectra total energy of NPCs' perturbation during storm time intervals at different sites suggests that a shell type of three-phase single transformer group seems to be more vulnerable in the storm. Although the low-latitude power grids usually show very small GIC, these can be used to investigate the potential risk of space weather to the system.

  8. Common origin of positive ionospheric storms at middle latitudes and the geomagnetic activity effect at low latitudes

    SciTech Connect

    Proelss, G.W. )

    1993-04-01

    The author looks for a correlation between two different atmospheric effects. They are a positive atmospheric storm (an anomalous increase in the F2 region ionization density), observed at middle latitudes, and the geomagnetic activity effect (the anomalous changes of temperature and gas density seen in the thermosphere), observed at low latitudes. A temporal correlation is sought to test the argument that both of these effects are the result of travelling atmospheric disturbances (TAD). A TAD is a pulselike atmospheric wave thought to be generated by substorm activity, and to propagate with high velocity (600 m/s) from polar latitudes toward equatorial latitudes. The author looks at data from five separate events correlating magnetic, ionospheric, and neutral atmospheric measurements. The conclusion is that there is a positive correlation between magnetic substorm activity at high latitudes, and positive ionospheric storms at middle latitudes and geomagnetic activity at low latitudes. The time correlations are consistent with high propagation speeds between these events. The author also presents arguments which indicate that the middle latitude positive ionospheric storms are not the result of electric field effects.

  9. Large Scale Ionospheric Response During March 17, 2013 Geomagnetic Storm: Reanalysis Based on Multiple Satellites Observations and TIEGCM Simulations

    NASA Astrophysics Data System (ADS)

    Yue, X.; Wang, W.; Schreiner, W. S.; Kuo, Y. H.; Lei, J.; Liu, J.; Burns, A. G.; Zhang, Y.; Zhang, S.

    2015-12-01

    Based on slant total electron content (TEC) observations made by ~10 satellites and ~450 ground IGS GNSS stations, we constructed a 4-D ionospheric electron density reanalysis during the March 17, 2013 geomagnetic storm. Four main large-scale ionospheric disturbances are identified from reanalysis: (1) The positive storm during the initial phase; (2) The SED (storm enhanced density) structure in both northern and southern hemisphere; (3) The large positive storm in main phase; (4) The significant negative storm in middle and low latitude during recovery phase. We then run the NCAR-TIEGCM model with Heelis electric potential empirical model as polar input. The TIEGCM can reproduce 3 of 4 large-scale structures (except SED) very well. We then further analyzed the altitudinal variations of these large-scale disturbances and found several interesting things, such as the altitude variation of SED, the rotation of positive/negative storm phase with local time. Those structures could not be identified clearly by traditional used data sources, which either has no gloval coverage or no vertical resolution. The drivers such as neutral wind/density and electric field from TIEGCM simulations are also analyzed to self-consistantly explain the identified disturbance features.

  10. Low-disturbance wind tunnels

    NASA Technical Reports Server (NTRS)

    Beckwith, I. E.; Applin, Z. T.; Stainback, P. C.; Maestrello, L.

    1986-01-01

    During the past years, there was an extensive program under way at the Langley Research Center to upgrade the flow quality in several of the large wind tunnels. This effort has resulted in significant improvements in flow quality in these tunnels and has also increased the understanding of how and where changes in existing and new wind tunnels are most likely to yield the desired improvements. As part of this ongoing program, flow disturbance levels and spectra were measured in several Langley tunnels before and after modifications were made to reduce acoustic and vorticity fluctuations. A brief description of these disturbance control features is given for the Low-Turbulence Pressure Tunnel, the 4 x 7 Meter Tunnel, and the 8 Foot Transonic Pressure Tunnel. To illustrate typical reductions in disturbance levels obtained in these tunnels, data from hot-wire or acoustic sensors are presented. A concept for a subsonic quiet tunnel designed to study boundary layer stability and transition is also presented. Techniques developed at Langley in recent years to eliminate the high intensity and high-frequency acoustic disturbances present in all previous supersonic wind tunnels are described. In conclusion, the low-disturbance levels present in atmospheric flight can now be simulated in wind tunnels over the speed range from low subsonic through high supersonic.

  11. Travelling ionospheric disturbances (TIDs) and tides observed by a super-resolution HF direction finding system

    NASA Astrophysics Data System (ADS)

    Hawlitschka, S.

    2006-02-01

    In this paper, the occurrence of tides, large-scale travelling ionospheric disturbances (LSTIDs) and medium-scale travelling ionospheric disturbances (MSTIDs) at mid-latitudes is investigated with respect to different geomagnetic conditions described by the K-index. As measurement system a high-frequency (HF) super-resolution direction-finding system has been used. An ionospherically refracted HF wave is affected by tilts and wave-like variations of the height of the ionosphere and its propagation is deviated from the great circle path. The temporal evolution of the deviation of the measured bearing and the respective power spectrum has been analyzed to detect the occurrence of TIDs and tides. During dusk and dawn, expected deviations of the bearing due to tides were found in agreement with the gradient of TEC in the respective TECmaps. At daytime, LSTIDs could generally be related to magnetic storms. Rarely they occurred as special events when the magnetosphere was extremely quiet (K<2). At nighttime, LSTIDs were found more often regardless of the K-index. MSTIDs passed in all measurements during all geomagnetic conditions at any time of the day or night. The power spectrum of the temporal evolution of the bearing showed characteristic shapes depending on whether LSTIDs were present or not. Parameters are defined which detect the occurrence of LSTIDs in the power spectrum.

  12. Investigation of traveling ionospheric disturbances

    NASA Technical Reports Server (NTRS)

    Grossi, M.; Estes, R. D.

    1981-01-01

    Maximum entropy power spectra of the ionospheric electron density were constructed to enable PINY to compare them with the power independently obtained by PINY with in situ measurements of ionospheric electron density and neutral species performed with instrumentation carried by the Atmospheric Explorer (AE) satellite. This comparison corroborated evidence on the geophysical reality of the alleged electron density irregularities detected by the ASTP dual frequency Doppler link. Roughly half of the localized wave structures which are confined to dimensions of 1800 km or less (as seen by an orbiting Doppler baseline) were found to be associated with the larger crest of the geomagnetic anomaly in the Southern (winter) Hemisphere in the morning. The observed nighttime structures are also associated with local peaks in the electron density.

  13. Temperature, density, and composition in the disturbed thermosphere from Esro 4 gas analyzer measurements - A global model

    NASA Technical Reports Server (NTRS)

    Jacchia, L. G.; Slowey, J. W.; Von Zahn, U.

    1977-01-01

    An analysis of density measurements of Ar, N2, O, and He made at 280 km with the gas analyzer aboard the polar-orbiting satellite Esro 4 has yielded a global model of the variations in temperature, density, and composition that occur in the disturbed thermosphere. In the model the increase of temperature over quiet conditions is a nonlinear function of the planetary geomagnetic index, its latitude profile being approximated by a fourth-power sin phi law, where phi is the 'invariant' magnetic latitude. A density wave proceeding from high latitudes is approximated by a fourth power cos phi law. A strong nonlinearity in the relation between the temperature variations and the variations in the height of the homopause explains a previously found behavioral difference in the variation of atomic oxygen during magnetic storms and during periods of sustained geomagnetic activity.

  14. Motion of the sources for type II and type IV radio bursts and flare-associated interplanetary disturbances

    NASA Technical Reports Server (NTRS)

    Sakurai, K.; Chao, J. K.

    1974-01-01

    Shock waves are indirectly observed as the source of type II radio bursts, whereas magnetic bottles are identified as the source of moving metric type IV radio bursts. The difference between the expansion speeds of these waves and bottles is examined during their generation and propagation near the flare regions. It is shown that, although generated in the explosive phase of flares, the bottles behave quite differently from the waves and that the bottles are generally much slower than the waves. It has been suggested that the waves are related to flare-associated interplanetary disturbances which produce SSC geomagnetic storms. These disturbances may, therefore, be identified as interplanetary shock waves. The relationship among magnetic bottles, shock waves near the sun, and flare-associated disturbances in interplanetary space is briefly discussed.

  15. Geomagnetic modification of the mid-latitude ionosphere - Toward a strategy for the improved forecasting of f0F2

    SciTech Connect

    Wrenn, G.L.; Rodger, A.S.

    1989-02-01

    An approach for modeling and forecasting the interspatial critical frequency (f0F2) at quiet and disturbed times is outlined. Statistical analyses of ionosonde data from the Argentine Islands (65 deg S) are used to define patterns for the main phase effects of midlatitude ionospheric storms. Extended to a number of stations, these could be incorporated into algorithms to permit the forecasting of maximum usable frequency for a few hours ahead and enhance the frequency management of shortwave radio communication, especially during a geomagnetic storm. Data from a complete solar cycle, 1971-1981, are used to determine the errors in the forecasts and to demonstrate that a useful advantage can be attained by this method. The rms error in f0F2 for 90,175 samples is 15.6 percent, which compares favorably with those obtained using forecasts based on quiet time values (20.4 percent) or the previous day's measurements (18 percent). 12 references.

  16. Managing Sleep Disturbances in Cirrhosis

    PubMed Central

    Zhao, Xun

    2016-01-01

    Sleep disturbances, particularly daytime sleepiness and insomnia, are common problems reported by patients suffering from liver cirrhosis. Poor sleep negatively impacts patients' quality of life and cognitive functions and increases mortality. Although sleep disturbances can be an early sign of hepatic encephalopathy (HE), many patients without HE still complain of poor quality sleep. The pathophysiology of these disturbances is not fully understood but is believed to be linked to impaired hepatic melatonin metabolism. This paper provides an overview for the clinician of common comorbidities contributing to poor sleep in patients with liver disease, mainly restless leg syndrome and obstructive sleep apnea. It discusses nondrug and pharmacologic treatment options in these patients, such as the use of light therapy and histamine (H1) blockers. PMID:27242950

  17. Disturbed Sleep and Postpartum Depression.

    PubMed

    Okun, Michele L

    2016-07-01

    The perinatal period introduces a myriad of changes. One important but often overlooked change is an increased reporting of sleep disturbance. Although casually regarded as a consequence of pregnancy or postpartum, there is emerging evidence implicating significant sleep disturbance, characterized by insomnia symptoms and/or poor sleep quality, with adverse outcomes, such as an increase in depressive symptomatology or the development postpartum depression (PPD). Significant consequences may arise as a result including issues with maternal-infant bonding, effective care for the infant, and behavioral or emotional difficulties in the infant. This review discusses the relevant literature as to how disturbed sleep during pregnancy as well as in the postpartum may increase the risk for PPD. PMID:27222140

  18. Ionospheric current source modeling and global geomagnetic induction using ground geomagnetic observatory data

    NASA Astrophysics Data System (ADS)

    Sun, J.; Kelbert, A.; Egbert, G. D.

    2015-10-01

    Long-period global-scale electromagnetic induction studies of deep Earth conductivity are based almost exclusively on magnetovariational methods and require accurate models of external source spatial structure. We describe approaches to inverting for both the external sources and three-dimensional (3-D) conductivity variations and apply these methods to long-period (T≥1.2 days) geomagnetic observatory data. Our scheme involves three steps: (1) Observatory data from 60 years (only partly overlapping and with many large gaps) are reduced and merged into dominant spatial modes using a scheme based on frequency domain principal components. (2) Resulting modes are inverted for corresponding external source spatial structure, using a simplified conductivity model with radial variations overlain by a two-dimensional thin sheet. The source inversion is regularized using a physically based source covariance, generated through superposition of correlated tilted zonal (quasi-dipole) current loops, representing ionospheric source complexity smoothed by Earth rotation. Free parameters in the source covariance model are tuned by a leave-one-out cross-validation scheme. (3) The estimated data modes are inverted for 3-D Earth conductivity, assuming the source excitation estimated in step 2. Together, these developments constitute key components in a practical scheme for simultaneous inversion of the catalogue of historical and modern observatory data for external source spatial structure and 3-D Earth conductivity.

  19. 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

  20. Ionospheric response to geomagnetic storm on July 14-17, 2012 in East Asia

    NASA Astrophysics Data System (ADS)

    Romanova, Elena; Zherebtsov, Gelii; Wang, Guojun; Zolotukhina, Nina; Polekh, Nelya; Wang, Xiao; Shi, Jiankui

    We study manifestation of intense geomagnetic storm on July 14-17, 2012 in the ionosphere high, middle and low latitudes. The peculiarity of the storm is that for nearly 30 hours the IMF Bz had southward direction (-20 ÷ -10 nT). We use data from the chains of stations located near the meridians 90E, 110E and 150E. The critical frequency (foF2) variation analysis showed that during the storm main phase the ionosphere response depends strongly on the local time of the sudden storm commencement so the negative perturbations were observed near the meridian 90E and positive perturbations were observed near the meridian 150E. At the end of the storm main phase the traveling ionospheric disturbances (TIDs) were observed at all stations. The critical frequencies were extremely low during the storm recovery phase on July 16, 2012 at all stations and this phase lasted nearly three days. At the low-latitude station Hainan (19.5N, 109E) on July 16, 2012 the day foF2 values were the same as the night values. This intense and prolonged negative perturbation is a very rare event at low latitudes. Since prolonged negative disturbance is usually associated with a decrease in the ratio of concentration of atomic oxygen to that of molecular nitrogen [O]/[N2] which is transported by the disturbed thermospheric wind from auroral latitudes to middle and low, then we analyzed measuring [O]/[N2] (Global Ultraviolet Imager, http://guvi.jhuapl.edu/site/gallery/guvi-galleryl3on2.shtml). It found out that feature of the studied storm is very low values of [O]/[N2] which were observed on July 16 in the longitudinal sector 60 - 150E from high latitude almost to the equator. Modeling results of the ionospheric response to this storm are also presented. At low-latitudes the extreme low values of [O]/[N2] also can be one of the reasons of the prolonged negative disturbance. The work was supported by the Russian Foundation for Basic Research (grant 13-05-91159) and RF President Grant of Public

  1. Detection of the significant geomagnetic field signals in the interannual variations of Length-of-Day using wavelet method

    NASA Astrophysics Data System (ADS)

    Liu, Genyou; Duan, Pengshuo; Hao, Xiaoguang; Hu, Xiaogang

    2015-04-01

    correlation coefficient between LOD and ENSO will increase from 0.51 to 0.98. Consequently, we can conclude that the weak coherence after 1982 on 5.3-8.0 year scales between LOD and ENSO is mainly due to the disturbance of Aa signal, and the observed LOD series is the result of the interaction between ENSO and geomagnetic field signals.

  2. A Fast Algorithm for Automatic Detection of Ionospheric Disturbances Using GPS Slant Total Electron Content Data

    NASA Astrophysics Data System (ADS)

    Efendi, Emre; Arikan, Feza; Yarici, Aysenur

    2016-07-01

    Solar, geomagnetic, gravitational and seismic activities cause disturbances in the ionospheric region of upper atmosphere for space based communication, navigation and positioning systems. These disturbances can be categorized with respect to their amplitude, duration and frequency. Typically in the literature, ionospheric disturbances are investigated with gradient based methods on Total Electron Content (TEC) data estimated from ground based dual frequency Global Positioning System (GPS) receivers. In this study, a detection algorithm is developed to determine the variability in Slant TEC (STEC) data. The developed method, namely Differential Rate of TEC (DRoT), is based on Rate of Tec (RoT) method that is widely used in the literature. RoT is usually applied to Vertical TEC (VTEC) and it can be defined as normalized derivative of VTEC. Unfortunately, the resultant data obtained from the application of RoT on VTEC suffer from inaccuracies due to mapping function and the resultant values are very noisy which make it difficult to automatically detect the disturbance due to variability in the ionosphere. The developed DRoT method can be defined as the normalized metric norm (L2) between the RoT and its baseband trend structure. In this study, the error performance of DRoT is determined using synthetic data with variable bounds on the parameter set of amplitude, frequency and period of disturbance. It is observed that DRoT method can detect disturbances in three categories. For DRoT values less than 50%, there is no significant disturbance in STEC data. For DRoT values between 50 to 70 %, a medium scale disturbance can be observed. For DROT values over 70 %, severe disturbances such Large Scale Travelling Ionospheric Disturbances (TID) or plasma bubbles can be observed. When DRoT is applied to the GPS-STECdata for stations in high latitude, equatorial and mid-latitude regions, it is observed that disturbances with amplitudes larger than 10% of the difference between

  3. Sleep Disturbances in Frontotemporal Dementia.

    PubMed

    McCarter, Stuart J; St Louis, Erik K; Boeve, Bradley F

    2016-09-01

    Sleep disorders appear to be frequent comorbidities in patients with frontotemporal dementia (FTD). Insomnia and excessive daytime sleepiness commonly occur in patients with FTD and significantly contribute to caregiver burden and burnout. Sleep is severely fragmented in FTD patients, likely secondary to behavioral disturbances, other primary sleep disorders such as sleep disordered breathing and restless leg syndrome, and neurodegeneration of nuclei involved in sleep and wakefulness. Treatment of primary sleep disorders may improve excessive daytime sleepiness and sleep quality and may improve daytime cognitive functioning. Rapid eye movement (REM) sleep behavior disorder is rare in FTD and may be confused with excessive nocturnal activity due to disturbed circadian rhythm. The relationship between FTD, sleep quality, and sleep disorders requires further study to better understand the contribution of disturbed sleep to daytime neurocognitive functioning and quality of life in FTD. Further, future studies should focus on comparing sleep disturbances between different FTD syndromes, especially behavioral variant FTD and primary progressive aphasia. Comorbid sleep disorders should be promptly sought and treated in patients with FTD to improve patient and caregiver quality of life. PMID:27485946

  4. Identifying, Assisting the Disturbed Adolescent.

    ERIC Educational Resources Information Center

    Carlson, Patricia L.; Schaefer, William

    1986-01-01

    Educators are in an excellent position to identify seriously troubled young people. Major causes of adolescent problems are discussed, including drugs, parental failure, and biochemical disturbances. Educators can best intervene by becoming aware of support services within their own school and community. (TE)

  5. [Sleep Disturbances in the Elderly].

    PubMed

    Mahlberg, Richard

    2016-08-01

    Sleep disturbances are common in the elderly. Endogen regulation mechanisms are often unstable. Light treatment and melatonin are proved chronobiological interventions. Cataract surgery is effective to enhance the sleep-wake-rhythm.Mandibular advancement devices are a reliable alternative to continuous positive air pressure (CPAP) in obstructive sleep apnea syndrome (OSAS). PMID:27509339

  6. RESILIENCE OF ECOSYSTEMS TO DISTURBANCES

    EPA Science Inventory

    Resilience, in an ecological context, is one of several terms that characterize the response of an ecosystem to disturbance. Other such terms include persistence, resistance and stability. Two definitions of resilience have become prominent in the literature, both of which derive...

  7. State Definitions of Emotional Disturbance

    ERIC Educational Resources Information Center

    Wery, Jessica J.; Cullinan, Douglas

    2013-01-01

    This article examines definitions state education agencies use to describe the federal education disability called "emotional disturbance." State definitions were collected so that various aspects of them could be analyzed and compared with results of similar studies completed in the 1970s and 1980s. Among results are that state definitions have…

  8. The F region and topside ionosphere response to a strong geomagnetic storm at Arecibo

    NASA Astrophysics Data System (ADS)

    Gong, Yun; Zhou, Qihou; Zhang, Shao Dong; Aponte, NéStor; Sulzer, Michael; GonzáLez, Sixto A.

    2013-08-01

    analyze the data derived from the Arecibo incoherent scatter radar measurements to investigate the response of the F region and topside ionosphere to a strong geomagnetic storm that occurred during the period of 5-6 August 2011. The meridional wind was extremely enhanced at the early stage of the storm. The peak velocity reached approximately 300 m/s at an altitude of 340 km, which is seldom seen at the Arecibo latitude. During the storm, the vertical ion drift caused by the meridional wind was positively correlated with that caused by the electric field, which is opposite to the quiet time relationship. The disturbed vertical ion drifts resulted in large ionospheric perturbations in the F and topside regions. Several collapses were observed in hmF2 during the storm night. NmF2 rapidly increased after the storm and then decreased around midnight. At an altitude of 610 km, the concentration of H+ and O+, and the ratio of H+ over electron density all exhibited large variations. The ratio of H+ over electron density changed from less than 10% to more than 80% in a matter of 2 hours in the morning of 6 August. One explanation for such a behavior is that vertical transport dominates over charge exchange late at night due to the lower concentration of O+.

  9. A numerical simulation of the geomagnetic sudden commencement: 2. Plasma processes in the main impulse

    NASA Astrophysics Data System (ADS)

    Fujita, S.; Tanaka, T.; Kikuchi, T.; Fujimoto, K.; Itonaga, M.

    2003-12-01

    A geomagnetic sudden commencement (SC) is studied numerically based on a model of buffeting the magnetosphere by a solar wind density impulse. This paper treats two successive current systems in the main impulse (MI) phase. The two current systems have different current generating mechanisms. The first current generator appears behind the wavefront of a compressional disturbance launched by the impulse. The inertia current of the compressional mode is generated by free energy due to deceleration of plasma flows. A field-aligned current (FAC) is excited through mode conversion from the compressional wave in a VA gradient region. The magnetospheric flows and the ionospheric flows are not connected self-consistently to each other. The second generator is located in the tailward side of the cusp. It is the same as the generator of the region 1 current system. The current generated there is connected with the FAC with the region 1 sense via a diamagnetic current flowing around an isolated enhancement of pressure in the nightside equatorial magnetosphere. The pressure enhancement is induced through compression of the magnetospheric flank due to the solar wind impulse. In this period, plasma convection vortices appear both in the magnetosphere and in the ionosphere, which are correspondent to each other. This is a peculiar convection confined within the magnetosphere (the SC transient cell convection). This convection is driven though compression of the magnetospheric flank due to the solar wind impulse.

  10. The effects of solar-geomagnetically induced currents on electrical systems in nuclear power stations

    SciTech Connect

    Subudhi, M.; Carroll, D.P.; Kasturi, S.

    1994-01-01

    This report presents the results of a study to evaluate the potential effects of geomagnetically induced currents (GICs) caused by the solar disturbances on the in-plant electrical distribution system and equipment in nuclear power stations. The plant-specific electrical distribution system for a typical nuclear plant is modeled using the ElectroMagnetic Transient Program (EMTP). The computer model simulates online equipment and loads from the station transformer in the switchyard of the power station to the safety-buses at 120 volts to which all electronic devices are connected for plant monitoring. The analytical model of the plant`s electrical distribution system is studied to identify the transient effects caused by the half-cycle saturation of the station transformers due to GIC. This study provides results of the voltage harmonics levels that have been noted at various electrical buses inside the plant. The emergency circuits appear to be more susceptible to high harmonics due to the normally light load conditions. In addition to steady-state analysis, this model was further analyzed simulating various plant transient conditions (e.g., loss of load or large motor start-up) occurring during GIC events. Detail models of the plant`s protective relaying system employed in bus transfer application were included in this model to study the effects of the harmonic distortion of the voltage input. Potential harmonic effects on the uniterruptable power system (UPS) are qualitatively discussed as well.

  11. Geomagnetic pulsations-production/interpretation. Final scientific report 1 Sep 78-30 Sep 81

    SciTech Connect

    Maple, E.

    1982-09-01

    Work has been devoted to experimental studies of middle-latitude geomagnetic pulsations in the period range 0.2 to 50 minutes. The principal effort has been on the resonant periods of the pulsations which arise from hydromagnetic resonances in the magnetosphere. The resonant periods appear as peaks in the period distributions and frequency spectra of the pulsations. The present work utilizes polarization traces which provide continuous displays of the polarization of the pulsations in selected period bands. This analysis technique was conceived some time ago. The early studies established that hydromagnetic (HM) waves were frequently observed throughout the 0.2 to 50 minute period range and that waves of several different periods were often observed simultaneously during both magnetically quiet and disturbed intervals. That effort was terminated before the potentialities of the technique had been exploited, and the early results were not widely disseminated. Some of the original data have been resurrected for the initial work under this grant, and the analysis technique has been extended.

  12. Particle scattering and current sheet stability in the geomagnetic tail during the substorm growth phase

    SciTech Connect

    Pulkkinen, T.I.; Pellinen, R.J.; Koskinen, H.E.J. ); Baker, D.N. ); Buechner, J. ); Lopez, R.E. ); Dyson, R.L.; Frank, L.A. )

    1992-12-01

    The degree of pitch angle scattering and chaotization of various particle populations in the geomagnetic tail during the substorm growth phase is studied by utilizing the Tsyganenko 1989 magnetic field model. A temporally evolving magnetic field model for the growth phase is constructed by enhancing the near-Earth currents and thinning the current sheet from the values given by the static Tsyganenko model. Changing the field geometry toward an increasingly taillike configuration leads to pitch angle scattering of particles whose Larmor radii become comparable to the field line radius of curvature. Several different cases representing substorms with varying levels of magnetic disturbance have been studied. In each case, the field development during the growth phase leads to considerable scattering of the thermal electrons relatively close to the Earth. The current sheet regions where the electron motion is chaotic are magnetically mapped to the ionosphere and compared with low-altitude measurements of electron precipitation. The chaotization of the thermal electron population occurs within a few minutes of the substorm onset, and the ionospheric mappings of the chaotic regions in the equatorial plane compare well with the region of brightening auroras. Even though the temporal evolution of the complex plasma system cannot be self-consistently described by the temporal evolution of the empirical field model, these models can provide the most accurate estimates of the field parameters for tail stability calculations.

  13. Temporal fluctuations of the geomagnetic field affect pigeons' entire homing flight.

    PubMed

    Schiffner, Ingo; Wiltschko, Roswitha

    2011-07-01

    Tracks of pigeons, recorded with the help of GPS-receivers from two sites 30 km north and south of the Frankfurt loft, were analyzed in view of an influence of irregular fluctuations of the geomagnetic field. The data obtained were correlated with indices characterizing different aspects of these fluctuations. We found the best correlations with the index quantifying the average amplitude of the magnetic disturbance, and with an index that quantifies the average variability of the magnetic field on the day of release: stronger and more variable fluctuations lead to a counter-clockwise shift of the mean headings during the initial phase at the release site and the following departure phase, but not during the final homing phase leading to the loft. The steadiness of flight was not affected during the initial phase; however, during the later parts of the homing flight, stronger fluctuations, as well as higher variability in the magnetic field led to a marked decrease in steadiness. This continuing effect of magnetic fluctuations indicates that magnetic factors not only affect the beginning, but remain an integral part of the pigeons' navigational processes during the entire homing flight. PMID:21451981

  14. Steady induction effects in geomagnetism. Part 1C: Geomagnetic estimation of steady surficial core motions: Application to the definitive geomagnetic reference field models

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    1993-01-01

    In the source-free mantle/frozen-flux core magnetic earth model, the non-linear inverse steady motional induction problem was solved using the method presented in Part 1B. How that method was applied to estimate steady, broad-scale fluid velocity fields near the top of Earth's core that induce the secular change indicated by the Definitive Geomagnetic Reference Field (DGRF) models from 1945 to 1980 are described. Special attention is given to the derivation of weight matrices for the DGRF models because the weights determine the apparent significance of the residual secular change. The derived weight matrices also enable estimation of the secular change signal-to-noise ratio characterizing the DGRF models. Two types of weights were derived in 1987-88: radial field weights for fitting the evolution of the broad-scale portion of the radial geomagnetic field component at Earth's surface implied by the DGRF's, and general weights for fitting the evolution of the broad-scale portion of the scalar potential specified by these models. The difference is non-trivial because not all the geomagnetic data represented by the DGRF's constrain the radial field component. For radial field weights (or general weights), a quantitatively acceptable explication of broad-scale secular change relative to the 1980 Magsat epoch must account for 99.94271 percent (or 99.98784 percent) of the total weighted variance accumulated therein. Tolerable normalized root-mean-square weighted residuals of 2.394 percent (or 1.103 percent) are less than the 7 percent errors expected in the source-free mantle/frozen-flux core approximation.

  15. GPS slant total electron content accuracy using the single layer model under different geomagnetic regions and ionospheric conditions

    NASA Astrophysics Data System (ADS)

    Brunini, C.; Azpilicueta, F.

    2010-05-01

    The use of observations from the Global Positioning System (GPS) has significantly impacted the study of the ionosphere. As it is widely known, dual-frequency GPS observations can provide very precise estimation of the slant Total Electron Content (sTEC—the linear integral of the electron density along a ray-path) and that the precision level is bounded by the carrier-phase noise and multi-path effects on both frequencies. Despite its precision, GPS sTEC estimations can be systematically affected by errors in the estimation of the satellites and receivers by Inter-Frequency Biases (IFB) that are simultaneously determined with the sTEC. Thus, the ultimate accuracy of the GPS sTEC estimation is determined by the errors with which the IFBs are estimated. This contribution attempts to assess the accuracy of IFBs estimation techniques based on the single layer model for different ionospheric regions (low, mid and high magnetic latitude); different seasons (summer and winter solstices and spring and autumn equinoxes); different solar activity levels (high and low); and different geomagnetic conditions (quiet and very disturbed). The followed strategy relies upon the generation of a synthetic data set free of IFB, multi-path, measurement noise and of any other error source. Therefore, when a data set with such properties is used as the input of the IFB estimation algorithms, any deviation from zero on the estimated IFBs should be taken as indications of the errors introduced by the estimation technique. The truthfulness of this assessment work is warranted by the fact that the synthetic data sets resemble, as realistically as possible, the different conditions that may happen in the real ionosphere. The results of this work show that during the high solar activity period the accuracy for the estimated sTEC is approximately of ±10 TECu for the low geomagnetic region and of ±2.2 TECu for the mid-latitude. During low solar activity the accuracy can be assumed to be in

  16. 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.

  17. SuperDARN backscatter during intense geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Currie, J. L.; Waters, C. L.; Menk, F. W.; Sciffer, M. D.; Bristow, W. A.

    2016-06-01

    It is often stated that high-frequency radars experience a loss of backscatter during geomagnetic storm events. The occurrence of backscatter during 25 intense geomagnetic storms was examined using data from the Bruny Island and Kodiak radars and a superposed epoch analysis. It was found that while a reduction of backscatter occurred in the middle to far ranges, there was an increase in the amount of backscatter from close range following storm onset. Ray tracing showed that an enhanced charge density in the E region can reduce the chance of F region and increase the chance of E region backscatter. It was also shown that reduction in backscatter cannot be explained by D region absorption. Using a normalized SYM-H value, percentage time through recovery phase can be estimated during storm progression which allows a prediction of backscatter return in real time that accounts for varying storm recovery phase duration.

  18. Earth orientation parameters: excitation by atmosphere, oceans and geomagnetic jerks

    NASA Astrophysics Data System (ADS)

    Vondrak, Jan; Ron, Cyril

    2015-08-01

    It is well known that geophysical fluids (atmosphere, oceans) excite Earth orientation. The influence is known to be dominant for polar motion, partly responsible for length-of-day changes, and very small effects are now observable also in nutation. Very recently several authors (Holme and de Viron 2005, Gibert and le Mouel 2008, Malkin 2013) noted that sudden changes of Earth's speed of rotation and phase/amplitude of the free motions of its spin axis (Chandler wobble, Free core nutation) occur near the epochs of geomagnetic jerks (GMJ - rapid changes of the secular variations of geomagnetic field). By using the numerical integration of broad-band Liouville equations (Brzezinski 1994) we demonstrate that if non-periodical bell-like excitations of limited length (app. 1 year) around the epochs of GMJ are added to atmospheric and oceanic excitations, the agreement between observed and calculated Earth orientation parameters is improved significantly.

  19. International Geomagnetic Reference Field: the 12th generation

    NASA Astrophysics Data System (ADS)

    Thébault, Erwan; Finlay, Christopher C.; Beggan, Ciarán D.; Alken, Patrick; Aubert, Julien; Barrois, Olivier; Bertrand, Francois; Bondar, Tatiana; Boness, Axel; Brocco, Laura; Canet, Elisabeth; Chambodut, Aude; Chulliat, Arnaud; Coïsson, Pierdavide; Civet, François; Du, Aimin; Fournier, Alexandre; Fratter, Isabelle; Gillet, Nicolas; Hamilton, Brian; Hamoudi, Mohamed; Hulot, Gauthier; Jager, Thomas; Korte, Monika; Kuang, Weijia; Lalanne, Xavier; Langlais, Benoit; Léger, Jean-Michel; Lesur, Vincent; Lowes, Frank J.; Macmillan, Susan; Mandea, Mioara; Manoj, Chandrasekharan; Maus, Stefan; Olsen, Nils; Petrov, Valeriy; Ridley, Victoria; Rother, Martin; Sabaka, Terence J.; Saturnino, Diana; Schachtschneider, Reyko; Sirol, Olivier; Tangborn, Andrew; Thomson, Alan; Tøffner-Clausen, Lars; Vigneron, Pierre; Wardinski, Ingo; Zvereva, Tatiana

    2015-05-01

    The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, provide the spherical harmonic coefficients, and provide maps of the magnetic declination, inclination, and total intensity for epoch 2015.0 and their predicted rates of change for 2015.0-2020.0. We also update the magnetic pole positions and discuss briefly the latest changes and possible future trends of the Earth's magnetic field.

  20. Exploiting the geomagnetic distortion of inclined atmospheric showers

    NASA Astrophysics Data System (ADS)

    Billoir, Pierre; Settimo, Mariangela; Blanco, Miguel

    2016-02-01

    We propose a novel approach to the determination of the nature of ultra-high energy cosmic rays by exploiting the geomagnetic deviation of muons in nearly horizontal showers. The distribution of muons at ground level is well described by a simple parameterization providing a few shape parameters tightly correlated to Xmaxμ, the depth of maximal muon production, which is a mass indicator tightly correlated to the usual parameter Xmax, the depth of maximal development of the shower. We show that some constraints can be set on the predictions of hadronic models, especially by combining the geomagnetic distortion with standard measurements of the longitudinal profile. We discuss the precision needed to obtain significant results, and we propose a schematic layout of a detector.