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Sample records for geomagnetic storm variations

  1. Coronal mass ejections and geomagnetic storms: Seasonal variations

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.; McComas, D.J.

    1992-07-01

    The well-established semiannual geomagnetic cycle, with peak activity near the equinoxes, has been attributed to the angle between the solar rotation axis and the geomagnetic dipole, which modulates the GSM Bz component in the interplanetary magnetic field (MF). This effect is predicted to be accentuated in the shocked plasma ahead of fast coronal mass ejections (CMESs); its relevance to the internal fields of the ejecta is unclear. CMEs, particularly fast events driving interplanetary shocks, are the cause of almost all large geomagnetic storms near solar maximum. We use a set of CMEs identified by ISEE-3 observations of bidirectional electron streaming, plus IMF and geomagnetic data, to investigate the semiannual geomagnetic variation and its relation to CMEs. We find that the geomagnetic effectiveness of CMEs and post-shock solar wind is well-ordered by speed and by the southward component of the IMF in GSM coordinates, as well as by preexisting geomagnetic conditions. The post-shock seasonal effect, with geomagnetic effectiveness maximizing near April 5 for negative GSEQ By and near October 5 for positive GSEQ By, is identifiable in shock and shock/CME events, but not for CME events without leading shocks. When used to complement the more fundamental causal parameter of CME speed, the seasonal effect appears to have value for prediction of geomagnetic storms.

  2. Coronal mass ejections and geomagnetic storms: Seasonal variations

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.L.; Gosling, J.T.; McComas, D.J.

    1992-01-01

    The well-established semiannual geomagnetic cycle, with peak activity near the equinoxes, has been attributed to the angle between the solar rotation axis and the geomagnetic dipole, which modulates the GSM Bz component in the interplanetary magnetic field (MF). This effect is predicted to be accentuated in the shocked plasma ahead of fast coronal mass ejections (CMESs); its relevance to the internal fields of the ejecta is unclear. CMEs, particularly fast events driving interplanetary shocks, are the cause of almost all large geomagnetic storms near solar maximum. We use a set of CMEs identified by ISEE-3 observations of bidirectional electron streaming, plus IMF and geomagnetic data, to investigate the semiannual geomagnetic variation and its relation to CMEs. We find that the geomagnetic effectiveness of CMEs and post-shock solar wind is well-ordered by speed and by the southward component of the IMF in GSM coordinates, as well as by preexisting geomagnetic conditions. The post-shock seasonal effect, with geomagnetic effectiveness maximizing near April 5 for negative GSEQ By and near October 5 for positive GSEQ By, is identifiable in shock and shock/CME events, but not for CME events without leading shocks. When used to complement the more fundamental causal parameter of CME speed, the seasonal effect appears to have value for prediction of geomagnetic storms.

  3. Geomagnetic Field Variation during Winter Storm at Localized Southern and Northern High Latitude

    Indian Academy of Sciences (India)

    Babita Devi; Smita Dubey; Shailendra Saini; Rajni Devi; Rashmi Wahi; Ajay Dhar; S. K. Vijay; A. K. Gwal

    2008-03-01

    This paper presents the effect of geomagnetic storm on geomagnetic field components at Southern (Maitri) and Northern (Kiruna) Hemispheres. The Indian Antarctic Station Maitri is located at geom. long. 66.03° S; 53.21° E whereas Kiruna is located at geom. long. 67.52° N; 23.38° E. We have studied all the geomagnetic storms that occurred during winter season of the year 2004–2005. We observed that at Southern Hemisphere the variation is large as compared to the Northern Hemisphere. Geomagnetic field components vary when the interplanetary magnetic field is oriented in southward direction. Geomagnetic field components vary in the main phase of the ring current. Due to southward orientation of vertical component of IMF reconnection takes place all across the dayside that transports plasma and magnetic flux which create the geomagnetic field variation.

  4. Geomagnetic Storm Sudden Commencements

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Storm Sudden Commencements (ssc) 1868 to present: STORM1 and STORM2 Lists: (Some text here is taken from the International Association of Geomagnetism and Aeronomy...

  5. PAMELA's measurements of geomagnetic cutoff variations during the 14 December 2006 storm

    CERN Document Server

    Adriani, O; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; De Donato, C; de Nolfo, G A; De Santis, C; De Simone, N; Di Felice, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mikhailov, M Mergé V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G I; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N

    2016-01-01

    Data from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment were used to measure the geomagnetic cutoff for high-energy (>80 MeV) protons during the 14 December 2006 geomagnetic storm. The variations of the cutoff latitude as a function of rigidity were studied on relatively short timescales, corresponding to spacecraft orbital periods (94 min). Estimated cutoff values were compared with those obtained by means of a trajectory tracing approach based on a dynamical empirical modeling of the Earth's magnetosphere. We found significant variations in the cutoff latitude, with a maximum suppression of about 7 deg at lowest rigidities during the main phase of the storm. The observed reduction in the geomagnetic shielding and its temporal evolution were related to the changes in the magnetospheric configuration, investigating the role of interplanetary magnetic field, solar wind and geomagnetic parameters. PAMELA's results represent the first direct measurement...

  6. Analysis of the Solar Diameter Variations at July, 1986 and the Geomagnetic Storm of March, 1989

    Science.gov (United States)

    Humberto Andrei, Alexandre; Garcia, Marcos A.; Papa, Andres R. R.; Calderari Boscardin, Sergio; Lousada Penna, Jucira; Sigismondi, Costantino

    2015-08-01

    In this work, we have a well-known event in scientific literature used to illustrate our investigation on the viability of the solar diameter variation be a precursor for the occurrence of sets of coronal mass ejections, and thus, for geomagnetic storms, as noted in previous works of our group, but now, in a time scale of a few days. The selected event was that of March 13, 1989, a strong geomagnetic storm that made the Hydro-Quebec power grid fall down by 9 hours, damaging the local economy in millions of dollars. At the same time we have investigated a time interval belonging to a solar minimum period, on July 1986, prior to the rising phase and solar maximum of Solar Cycle 22, to compare with the geomagnetic pattern, as well as with the solar diameter behavior along these periods of low solar and geomagnetic activity. We used the time series of the CERGA’s astrolabe (because its dataset is long enough as to comprise both time periods of the analysis), the geomagnetic index AP and the H geomagnetic component from the Tatuoca Magnetic Observatory (because it is near to the geomagnetic equator and with the extra aim of checking the sensitivity of its magnetometers to global events).

  7. Longitudinal variations of positive dayside ionospheric storms related to recurrent geomagnetic storms

    CERN Document Server

    Dmitriev, A V; Brahmanandam, P S; Chang, L C; Chen, K -T; Tsai, L -C

    2013-01-01

    We have performed an analysis of case events and statistics of positive ionospheric storms in the dayside region of the equatorial ionization anomaly during recurrent geomagnetic storms (RGSs), which dominate in geomagnetic and ionospheric conditions on the declining phase of solar activity in 2004 to 2008. It is shown that total electron content (TEC) has a tendency to minimize before the beginning of RGSs and to peak 3 to 4 days after, i.e. on the RGS recovery phase produced by high-intensity long-duration continuous auroral activity. The maximum of TEC coincides with the maximum of solar wind velocity within high-speed solar wind streams. An analysis of electron content vertical profiles, derived from two independent methods using ionosondes and COSMIC/FORMOSAT-3 radio occultation, showed that in the maximum of an ionospheric storm on 28 March 2008, the F2 layer thickens, NmF2 increases by ~50% and hmF2 elevates by a few tens of kilometers. The response of positive ionospheric storms to solar, heliospheric...

  8. Extreme Geomagnetic Storms - 1868 - 2010

    Science.gov (United States)

    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

  9. Hazards of geomagnetic storms

    Science.gov (United States)

    Herzog, D.C.

    1992-01-01

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

  10. Ionospheric redistribution during geomagnetic storms.

    Science.gov (United States)

    Immel, T J; Mannucci, A J

    2013-12-01

    [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 (Dststorm 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.

  11. Analysis of geomagnetic storm variations and count-rate of cosmic ray muons recorded at the Brazilian southern space observatory

    Energy Technology Data Exchange (ETDEWEB)

    Frigo, Everton [University of Sao Paulo, USP, Institute of Astronomy, Geophysics and Atmospheric Sciences, IAG/USP, Department of Geophysics, Sao Paulo, SP (Brazil); Savian, Jairo Francisco [Space Science Laboratory of Santa Maria, LACESM/CT, Southern Regional Space Research Center, CRS/INPE, MCT, Santa Maria, RS (Brazil); Silva, Marlos Rockenbach da; Lago, Alisson dal; Trivedi, Nalin Babulal [National Institute for Space Research, INPE/MCT, Division of Space Geophysics, DGE, Sao Jose dos Campos, SP (Brazil); Schuch, Nelson Jorge, E-mail: efrigo@iag.usp.br, E-mail: savian@lacesm.ufsm.br, E-mail: njschuch@lacesm.ufsm.br, E-mail: marlos@dge.inpe.br, E-mail: dallago@dge.inpe.br, E-mail: trivedi@dge.inpe.br [Southern Regional Space Research Center, CRS/INPE, MCT, Santa Maria, RS (Brazil)

    2007-07-01

    An analysis of geomagnetic storm variations and the count rate of cosmic ray muons recorded at the Brazilian Southern Space Observatory -OES/CRS/INPE-MCT, in Sao Martinho da Serra, RS during the month of November 2004, is presented in this paper. The geomagnetic measurements are done by a three component low noise fluxgate magnetometer and the count rates of cosmic ray muons are recorded by a muon scintillator telescope - MST, both instruments installed at the Observatory. The fluxgate magnetometer measures variations in the three orthogonal components of Earth magnetic field, H (North-South), D (East-West) and Z (Vertical), with data sampling rate of 0.5 Hz. The muon scintillator telescope records hourly count rates. The arrival of a solar disturbance can be identified by observing the decrease in the muon count rate. The goal of this work is to describe the physical morphology and phenomenology observed during the geomagnetic storm of November 2004, using the H component of the geomagnetic field and vertical channel V of the multi-directional muon detector in South of Brazil. (author)

  12. Geomagnetic Principal Magnetic Storms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The abbreviations used for observatory names are as follows: GEOMAGNETIC OBSERVATORIES Code Station Geomagnetic Latitude ABG Alibag AMS Martin de Vivie. These data...

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

    Science.gov (United States)

    Singh, Vir; Dharwan, Maneesha

    2016-07-01

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

  14. A study on severe geomagnetic storms and earth’s magnetic field H variations, Sunspots and formation of cyclone

    Directory of Open Access Journals (Sweden)

    M.V.Subramanian

    2016-10-01

    Full Text Available For our study, we have selected ten severe geomagnetic storms. Which occurred during the years 1994 to 2015. Here great geomagnetic storm of Dst index from -422 nT to -17 nT are taken. These storms are significant not only because of the extremely high magnetic activity but also due to their great impact on the geomagnetosphere. We have studied the relation between severe geomagnetic storms with Earth’s magnetic field in horizontal component (H constant and also studied the relation between Dst index with sunspots number. The H constant data from Kyoto data centre and Dst index, Ap index, Kp index from OMNI data centre. We have found that the Dst is at very lowest level in this storm period, Ap index Kp index are increased in severe geomagnetic storm period and H Constant is at very lowest level in storm period. We have found that geomagnetic storms were induced to form the cyclones within 29 days. The Sunspots numbers are increased to induce to geomagnetic storm within 5 – 15 days

  15. TEC variations along an East Euro-African chain during 5th April 2010 geomagnetic storm

    Science.gov (United States)

    Shimeis, A.; Borries, C.; Amory-Mazaudier, C.; Fleury, R.; Mahrous, A. M.; Hassan, A. F.; Nawar, S.

    2015-05-01

    In this paper, we analyzed the variations of TEC along a latitudinal East Euro-African chain, during the storm of April 5, 2010. We observed a large asymmetry between the two hemispheres. We detected the presence of a TID in the Northern hemisphere on April 5. The propagation time of the TID from high to low latitudes and the speed of the TID was determined. On April 5, 6 and 7, we observed a decrease of the TEC and changes of the NO+ in the Northern hemisphere. This depletion is caused by the large-scale thermospheric wind disturbances due to Joule heating dissipation in the auroral zone.

  16. Modeling the ocean effect of geomagnetic storms

    DEFF Research Database (Denmark)

    Olsen, Nils; Kuvshinov, A.

    2004-01-01

    At coastal sites, geomagnetic variations for periods shorter than a few days are strongly distorted by the conductivity of the nearby sea-water. This phenomena, known as the ocean (or coast) effect, is strongest in the magnetic vertical component. We demonstrate the ability to predict the ocean...... if the oceans are considered. Our analysis also indicates a significant local time asymmetry (i.e., contributions from spherical harmonics other than P-I(0)), especially during the main phase of the storm....

  17. Geomagnetic storms: historical perspective to modern view

    Science.gov (United States)

    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.

  18. Solar cycle distribution of major geomagnetic storms

    Institute of Scientific and Technical Information of China (English)

    Gui-Ming Le; Zi-Yu Cai; Hua-Ning Wang; Zhi-Qiang Yin; Peng Li

    2013-01-01

    We examine the solar cycle distribution of major geomagnetic storms (Dst ≤-100 nT),including intense storms at the level of-200 nT< Dst ≤-100 nT,great storms at-300 nT< Dst ≤-200 nT,and super storms at Dst ≤-300 nT,which occurred during the period of 1957-2006,based on Dst indices and smoothed monthly sunspot numbers.Statistics show that the majority (82%) of the geomagnetic storms at the level of Dst ≤-100 nT that occurred in the study period were intense geomagnetic storms,with 12.4% ranked as great storms and 5.6% as super storms.It is interesting to note that about 27% of the geomagnetic storms that occurred at all three intensity levels appeared in the ascending phase of a solar cycle,and about 73% in the descending one.Statistics also show that 76.9% of the intense storms,79.6% of the great storms and 90.9% of the super storms occurred during the two years before a solar cycle reached its peak,or in the three years after it.The correlation between the size of a solar cycle and the percentage of major storms that occurred,during the period from two years prior to maximum to three years after it,is investigated.Finally,the properties of the multi-peak distribution for major geomagnetic storms in each solar cycle is investigated.

  19. The latitudinal distribution of the baseline geomagnetic field during the March 17, 2015 geomagnetic storm

    Science.gov (United States)

    Alberti, Tommaso; Piersanti, Mirko; Lepreti, Fabio; Vecchio, Antonio; De Michelis, Paola; Villante, Umberto; Carbone, Vincenzo

    2016-04-01

    Geomagnetic storms (GS) are global geomagnetic disturbances that result from the interaction between magnetized plasma that propagates from the Sun and plasma and magnetic fields in the near-Earth space plasma environment. The Dst (Disturbance Storm Time) global Ring Current index is still taken to be the definitive representation for geomagnetic storm and is used widely by researcher. Recent in situ measurements by satellites passing through the ring-current region (i.e. Van Allen probes) and computations with magnetospheric field models showed that there are many other field contributions on the geomagnetic storming time variations at middle and low latitudes. Appling the Empirical Mode Decomposition [Huang et al., 1998] to magnetospheric and ground observations, we detect the different magnetic field contributions during a GS and introduce the concepts of modulated baseline and fluctuations of the geomagnetic field. In this work, we apply this method to study the latitudinal distribution of the baseline geomagnetic field during the St. Patrick's Day Geomagnetic Storm 2015 in order to detect physical informations concerning the differences between high-latitude and equatorial ground measurements.

  20. Solar wind variations and geomagnetic storms: A study of individual storms based on a high time resolution ISEE-3 data

    Energy Technology Data Exchange (ETDEWEB)

    Akasofu, S.h.; Olmsted, C.; Smith, E.J.; Tsurutani, B.; Okida, R.; Baker, D.N.

    1985-01-01

    We employ two independent methods to determine the relationship between the epsilon parameter and the total energy dissipation rate of the magnetosphere by selecting disturbed periods from the same data set used by Baker et al. (1983). Specifically, four storms are examined in detail, since the accuracy of estimating U/sub T/ is significantly improved during disturbed periods. The first method assumes U/sub T/ = M/sub A//sup 2alpha/epsilon, where M/sub A/ is the Alfven Mach number and ..cap alpha.. varies with time. The second method considers a linear, time-invariant dynamic system with epsilon as input and U/sub T/ as output. This means U/sub T/ = W*epsilon, where * is convolution and W is a transfer function characteristic of the system. It is found that ..cap alpha.. values fluctuate mainly between 0 and -0.25. The transfer function analysis indicates that W often resembles a delta-function or a narrow rectangular impulse. Both results give the same implication (namely, U/sub T/ approx.epsilon) and thus are consistent with the view that the magnetosphere is primarily a directly driven system during disturbed periods.

  1. Research on Historical Records of Geomagnetic Storms

    Science.gov (United States)

    Lakhina, G. S.; Alex, S.; Tsurutani, B. T.; Gonzalez, W. D.

    In recent times, there has been keen interest in understanding Sun-Earth connection events, such as solar flares, CMEs and concomitant magnetic storms. Magnetic storms are the most dramatic and perhaps important component of space weather effects on Earth. Super-intense magnetic storms (defined here as those with Dst cause life-threatening power outages, satellite damage, communication failures and navigational problems. However, the data for such magnetic storms is rather scarce. For example, only one super-intense magnetic storm has been recorded (Dst=-640 nT, March 13, 1989) during the space-age (since 1958), although such storms may have occurred many times in the last 160 years or so when the regular observatory network came into existence. Thus, research on historical geomagnetic storms can help to create a good data base for intense and super-intense magnetic storms. From the application of knowledge of interplanetary and solar causes of storms gained from the spaceage observations applied to the super-intense storm of September 1-2, 1859, it has been possible to deduce that an exceptionally fast (and intense) magnetic cloud was the interplanetary cause of this geomagnetic storm with a Dst -1760 nT, nearly 3 times as large as that of March 13, 1989 super-intense storm. The talk will focus on super-intense storms of September 1-2, 1859, and also discuss the results in the context of some recent intense storms.

  2. Quantifying Power Grid Risk from Geomagnetic Storms

    Science.gov (United States)

    Homeier, N.; Wei, L. H.; Gannon, J. L.

    2012-12-01

    We are creating a statistical model of the geophysical environment that can be used to quantify the geomagnetic storm hazard to power grid infrastructure. Our model is developed using a database of surface electric fields for the continental United States during a set of historical geomagnetic storms. These electric fields are derived from the SUPERMAG compilation of worldwide magnetometer data and surface impedances from the United States Geological Survey. This electric field data can be combined with a power grid model to determine GICs per node and reactive MVARs at each minute during a storm. Using publicly available substation locations, we derive relative risk maps by location by combining magnetic latitude and ground conductivity. We also estimate the surface electric fields during the August 1972 geomagnetic storm that caused a telephone cable outage across the middle of the United States. This event produced the largest surface electric fields in the continental U.S. in at least the past 40 years.

  3. Ionospheric Effects of Geomagnetic Storms in Different Longitude Sectors

    Institute of Scientific and Technical Information of China (English)

    G. A. Zherebtsov; O.M. Pirog; N.M. Polekh

    2005-01-01

    This paper analyzes the state of the ionosphere during two geomagnetic storms of a different intensity evolving in different sectors of local time in different seasons. There were used the data from a network of ionospheric stations located in the opposite longitudinal sectors of 80°-150° E and 250°-310° E.This analysis has permitted us to conclude that the detected differences in the variations of the disturbances are likely to be determined by the local time difference of the geomagnetic storm development, its intensity and by the different illumination conditions of the ionosphere.

  4. The Causes of Geomagnetic Storms During Solar Maximum

    Science.gov (United States)

    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).

  5. Letter to the Editor: Geomagnetic storm effects at low latitudes

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    Full Text Available The geomagnetic horizontal (H field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday hours over and above the usual dawn-maximum and dusk-minimum seen at any mid-latitude stations around the world. These slow and persistent additional decreases of H of disturbance daily variation at equatorial latitudes 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.Key words. Ionosphere (electric fields and currents · Magnetospheric physics (electric fields; storms and substorms

  6. Principles of major geomagnetic storms forecasting

    Science.gov (United States)

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

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

  7. Estimation of cold plasma outflow during geomagnetic storms

    CERN Document Server

    Haaland, S; André, M; Maes, L; Baddeley, L; Barakat, A; Chappell, R; Eccles, V; Johnsen, C; Lybekk, B; Li, K; Pedersen, A; Schunk, R; Welling, D

    2016-01-01

    Low-energy ions of ionospheric origin constitute a significant contributor to the magnetospheric plasma population. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and typically in regions of space where spacecraft attain a positive charge due to solar illumination. Cold ions are therefore shielded from the satellite particle detectors. Furthermore, spacecraft can only cover key regions of ion outflow during segments of their orbit, so additional complications arise if continuous longtime observations, such as during a geomagnetic storm, are needed. In this paper we suggest a new approach, based on a combination of synoptic observations and a novel technique to estimate the flux and total outflow during the various phases of geomagnetic storms. Our results indicate large variations in both outflow rates and transport throughout the storm. Prior to the storm main phase, outflow rates are moderate, and the cold ions are mainly emanating from moderately sized ...

  8. Long-term rise in geomagnetic activity - A close connection between quiet days and storms

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2000-01-01

    Geomagnetic quiet days and magnetic storms are naturally believed to be due to very different solar wind conditions. In this study we however demonstrate that the long-term variation of geomagnetic quiet and disturbed days are surprisingly similar. By the use of daily averages of the geomagnetic...

  9. Space Weather Monitoring for ISS Geomagnetic Storm Studies

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  11. Geomagnetic storm effects on GPS based navigation

    Directory of Open Access Journals (Sweden)

    P. V. S. Rama Rao

    2009-05-01

    Full Text Available The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena.

    Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB L-band scintillation events, adversely affecting the GPS based navigation.

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

    Science.gov (United States)

    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.

  13. Thermospheric mass density variations during geomagnetic storms and a prediction model based on the merging electric field

    NARCIS (Netherlands)

    Liu, R.; Lühr, H.; Doornbos, E.; Ma, S.Y.

    2010-01-01

    With the help of four years (2002–2005) of CHAMP accelerometer data we have investigated the dependence of low and mid latitude thermospheric density on the merging electric field, Em, during major magnetic storms. Altogether 30 intensive storm events (Dstmin <−100 nT) are chosen for a statistical s

  14. Solar Wind Charge Exchange During Geomagnetic Storms

    Science.gov (United States)

    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.

  15. Geomagnetic storm and equatorial spread-F

    Directory of Open Access Journals (Sweden)

    F. Becker-Guedes

    2004-09-01

    Full Text Available In August 2000, a new ionospheric sounding station was established at Sao Jose dos Campos (23.2° S, 45.9° W; dip latitude 17.6° S, Brazil, by the University of Vale do Paraiba (UNIVAP. Another ionospheric sounding station was established at Palmas (10.2° S, 48.2° W; dip latitude 5.5° S, Brazil, in April 2002, by UNIVAP in collaboration with the Lutheran University Center of Palmas (CEULP, Lutheran University of Brazil (ULBRA. Both the stations are equipped with digital ionosonde of the type known as Canadian Advanced Digital Ionosonde (CADI. In order to study the effects of geomagnetic storms on equatorial spread-F, we present and discuss three case studies, two from the ionospheric sounding observations at Sao Jose dos Campos (September and November 2000 and one from the simultaneous ionospheric sounding observations at Sao Jose dos Campos and Palmas (July 2003. Salient features from these ionospheric observations are presented and discussed in this paper. It has been observed that sometimes (e.g. 4-5 November 2000 the geomagnetic storm acts as an inhibitor (high strong spread-F season, whereas at other times (e.g. 11-12 July 2003 they act as an initiator (low strong spread-F season, possibly due to corresponding changes in the quiet and disturbed drift patterns during different seasons.

  16. Storm time spatial variations in TEC during moderate geomagnetic storms in extremely low solar activity conditions (2007-2009) over Indian region

    Science.gov (United States)

    Sunda, Surendra; Vyas, B. M.; Khekale, P. V.

    2013-07-01

    The total electron content (TEC) measurements from a network of GPS receivers were analyzed to investigate the storm time spatial response of ionosphere over the Indian longitude sector. The GPS receivers from the GPS Aided Geo Augmented Navigation (GAGAN) network which are uniquely located around the ˜77°E longitude are used in the present study so as to get the complete latitudinal coverage from the magnetic equator to low mid-latitude region. We have selected the most intense storms but of moderate intensity (-100 nT extremely low solar activity conditions in 2007-2009. Though the storms are of moderate intensity, their effects on equatorial to low mid-latitude ionosphere are found to be very severe as TEC deviations are more than 100% during all the storms studied. Interesting results in terms of spatial distribution of positive/negative effects during the main/early recovery phase of storms are noticed. The maximum effect was observed at crest region during two storms whereas another two storms had maximum effect near the low mid-latitude region. The associated mechanisms like equatorial electrodynamics and neutral dynamics are segregated and explained using the TIMED/GUVI and EEJ data during these storms. The TEC maps are generated to investigate the storm time development/inhibition of equatorial ionization anomaly (EIA).

  17. Positive and negative ionospheric responses to the March 2015 geomagnetic storm from BDS observations

    Science.gov (United States)

    Jin, Shuanggen; Jin, Rui; Kutoglu, H.

    2017-06-01

    The most intense geomagnetic storm in solar cycle 24 occurred on March 17, 2015, and the detailed ionospheric storm morphologies are difficultly obtained from traditional observations. In this paper, the Geostationary Earth Orbit (GEO) observations of BeiDou Navigation Satellite System (BDS) are for the first time used to investigate the ionospheric responses to the geomagnetic storm. Using BDS GEO and GIMs TEC series, negative and positive responses to the March 2015 storm are found at local and global scales. During the main phase, positive ionospheric storm is the main response to the geomagnetic storm, while in the recovery phase, negative phases are pronounced at all latitudes. Maximum amplitudes of negative and positive phases appear in the afternoon and post-dusk sectors during both main and recovery phases. Furthermore, dual-peak positive phases in main phase and repeated negative phase during the recovery are found from BDS GEO observations. The geomagnetic latitudes corresponding to the maximum disturbances during the main and recovery phases show large differences, but they are quasi-symmetrical between southern and northern hemispheres. No clear zonal propagation of traveling ionospheric disturbances is detected in the GNSS TEC disturbances at high and low latitudes. The thermospheric composition variations could be the dominant source of the observed ionospheric storm effect from GUVI [O]/[N2] ratio data as well as storm-time electric fields. Our study demonstrates that the BDS (especially the GEO) observations are an important data source to observe ionospheric responses to the geomagnetic storm.

  18. Positive and negative ionospheric responses to the March 2015 geomagnetic storm from BDS observations

    Science.gov (United States)

    Jin, Shuanggen; Jin, Rui; Kutoglu, H.

    2017-01-01

    The most intense geomagnetic storm in solar cycle 24 occurred on March 17, 2015, and the detailed ionospheric storm morphologies are difficultly obtained from traditional observations. In this paper, the Geostationary Earth Orbit (GEO) observations of BeiDou Navigation Satellite System (BDS) are for the first time used to investigate the ionospheric responses to the geomagnetic storm. Using BDS GEO and GIMs TEC series, negative and positive responses to the March 2015 storm are found at local and global scales. During the main phase, positive ionospheric storm is the main response to the geomagnetic storm, while in the recovery phase, negative phases are pronounced at all latitudes. Maximum amplitudes of negative and positive phases appear in the afternoon and post-dusk sectors during both main and recovery phases. Furthermore, dual-peak positive phases in main phase and repeated negative phase during the recovery are found from BDS GEO observations. The geomagnetic latitudes corresponding to the maximum disturbances during the main and recovery phases show large differences, but they are quasi-symmetrical between southern and northern hemispheres. No clear zonal propagation of traveling ionospheric disturbances is detected in the GNSS TEC disturbances at high and low latitudes. The thermospheric composition variations could be the dominant source of the observed ionospheric storm effect from GUVI [O]/[N2] ratio data as well as storm-time electric fields. Our study demonstrates that the BDS (especially the GEO) observations are an important data source to observe ionospheric responses to the geomagnetic storm.

  19. On polar daily geomagnetic variation

    Directory of Open Access Journals (Sweden)

    Paola De Michelis

    2015-11-01

    Full Text Available The aim of this work is to investigate the nature of the daily magnetic field perturbations produced by ionospheric and magnetospheric currents at high latitudes. We analyse the hourly means of the X and Y geomagnetic field components recorded by a meridian chain of permanent geomagnetic observatories in the polar region of the Northern Hemisphere during a period of four years (1995-1998 around the solar minimum. We apply a mathematical method, known as natural orthogonal component (NOC, which is capable of characterizing the dominant modes of the geomagnetic field daily variability through a set of empirical orthogonal functions (EOFs. Using the first two modes we reconstruct a two-dimensional equivalent current representation of the ionospheric electric currents, which contribute substantially to the geomagnetic daily variations. The obtained current structures resemble the equivalent current patterns of DP2 and DP1. We characterize these currents by studying their evolution with the geomagnetic activity level and by analysing their dependence on the interplanetary magnetic field. The obtained results support the idea of a coexistence of two main processes during all analysed period although one of them, the directly driven process, represents the dominant component of the geomagnetic daily variation.

  20. Acceleration and loss of relativistic electrons during small geomagnetic storms.

    Science.gov (United States)

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

    2015-12-16

    Past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms (Dst > -50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result in flux depletion than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. Small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.

  1. Statistical Study of False Alarms of Geomagnetic Storms

    DEFF Research Database (Denmark)

    Leer, Kristoffer; Vennerstrøm, Susanne; Veronig, A.

    Coronal Mass Ejections (CMEs) are known to cause geomagnetic storms on Earth. However, not all CMEs will trigger geomagnetic storms, even if they are heading towards the Earth. In this study, front side halo CMEs with speed larger than 500 km/s have been identified from the SOHO LASCO catalogue....... A subset of these halo CMEs did not cause a geomagnetic storm the following four days and have therefore been considered as false alarms. The properties of these events are investigated and discussed here. Their statistics are compared to the geo-effective CMEs. The ability to identify potential false...... alarms is considered as an important factor when forecasting geomagnetic storms. It would therefore be very helpful if there were a signature in the solar data that could indicate that a CME is a false alarm. The strength and position of associated flares have been considered as possible candidates...

  2. Statistical Study of False Alarms of Geomagnetic Storms

    DEFF Research Database (Denmark)

    Leer, Kristoffer; Vennerstrøm, Susanne; Veronig, A.;

    Coronal Mass Ejections (CMEs) are known to cause geomagnetic storms on Earth. However, not all CMEs will trigger geomagnetic storms, even if they are heading towards the Earth. In this study, front side halo CMEs with speed larger than 500 km/s have been identified from the SOHO LASCO catalogue....... A subset of these halo CMEs did not cause a geomagnetic storm the following four days and have therefore been considered as false alarms. The properties of these events are investigated and discussed here. Their statistics are compared to the geo-effective CMEs. The ability to identify potential false...... alarms is considered as an important factor when forecasting geomagnetic storms. It would therefore be very helpful if there were a signature in the solar data that could indicate that a CME is a false alarm. The strength and position of associated flares have been considered as possible candidates...

  3. The responses of the thermosphere due to a geomagnetic storm: A MHD model

    Science.gov (United States)

    Wu, S. T.; Chang, S.

    1972-01-01

    A magnetohydrodynamics theory was used to study the dynamic response of the neutral atmosphere to a geomagnetic storm. A full set of magnetohydrodynamic equations appropriate for the present problem is derived and their various orders of approximation are discussed in some detail. In order to demonstrate the usefulness of this theoretical model, the May 1967 geomagnetic storm data were used in the resulting set of nonlinear, time dependent, partial differential magnetohydrodynamic equations to calculate variations of the thermosphere due to the storm. The numerical results are presented for wind speeds, electric field strength, and amount of joule heating at a constant altitude for the data recorded. Data show that the strongest thermospheric responses are at the polar region becoming weaker in the equatorial region. This may lead to the speculation that a thermospheric wave is generated in the polar region due to the geomagnetic storm which propagates towards the equator.

  4. Historically Large Geomagnetic Storms and Potential Electric Power Grid Impacts

    Science.gov (United States)

    Kappenman, J. G.

    2004-05-01

    While recent work has been done to examine the possible Dst Intensity of historically large geomagnetic storms, the impacts caused to modern day electric power grids from these storms occurs due to rapid rate-of-change of regional geomagnetic fields which in most cases are driven by large ionospheric electrojet current intensifications. These temporally and spatially dynamic disturbance morphologies are not well-characterized by Dst or other broad geomagnetic storm indices. For estimates of storm intensity that correctly scale the threat potential to electric power grids, it is necessary to describe the rate-of-change of geomagnetic field. The rate-of-change of the geomagnetic field (dB/dt usually measured in nT/min) creates at ground level a geoelectric field that causes the flow of geomagnetically-induced currents (GIC) through ground connection points in electric power grids. Therefore in general, the larger the dB/dt, the larger the resulting geo-electric field and GIC in exposed power grid infrastructures and the greater the operational impact these induced currents will have on the power grid. Both extensive modeling analysis and recent operational experience suggests that power grids are becoming more vulnerable to geomagnetic storms as they grow in size and complexity. Also, large power grid blackouts have occurred at relatively low geomagnetic storm intensities. For example, the regional disturbance intensity that triggered the Hydro Quebec collapse during the March 13, 1989 Superstorm only reached an intensity of 479 nT/min. Large numbers of power system impacts in the United States were also observed for intensities that ranged from 300 to 600 nT/min during this storm. Yet both recent and historical data indicate that storms with disturbance levels that range from 2000 nT/min to as much ~5000 nT/min may be possible over extensive regions at latitudes of concern for large continental power grids across North America and Europe. Large GIC have also been

  5. Impact of famous CEDAR, GEM and ISTP geomagnetic Storms on HF Radio Propagation

    Science.gov (United States)

    Blagoveshchensky, D.; Sergeeva, M.

    The mighty geomagnetic storms due to the extraordinary Sun s activity cause as a rule some impacts in these areas radiation effects on human and satellites commercial airlines outages electric power and other geomagnetic effects navigation and communication GPS effects ionospheric disturbances HF communication effects Therefore our scientific understanding of this activity is very important Joint efforts for example within the framework of the CAWSES enable progress in our ability to i identify critical inputs to specify the geospace environment at a level needed to minimize impacts on technology human society and life and ii support the development of robust models that predict conditions in geospace based on understanding of the Sun-Earth system and all of its interacting components In this study influence of 14 geomagnetic storms from a list of CEDAR GEM and ISTP storms within 1997-99 on radio propagation conditions have been investigated These conditions were estimated through variations of the MOF and LOF the maximum and lowest operation frequencies on each path from three high-latitude HF radio paths of North-west Russia before during and after a storm It was shown that the storm impact on the ionosphere and radio propagation for each storm has an individual character Nevertheless the common character of the certain manifestations during storm-time was revealed For example the frequency range MOF - LOF is getting wider several hours before a storm then it is sharply narrow during a storm-time and further it is expanded again several

  6. Ionospheric response to great geomagnetic storms during solar cycle 23

    Science.gov (United States)

    Merline Matamba, Tshimangadzo; Bosco Habarulema, John

    2016-07-01

    The analyses of ionospheric responses due to great geomagnetic storms i.e. Dst index 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 Physical mechanisms related to (but not limited to) composition changes and electric fields will be discussed.

  7. Extreme Geomagnetic Storms – 1868–2010

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Lefèvre, L.; Dumbović, M.

    2016-01-01

    occurring in May 1921 and the Quebec storm from March 1989. We identifykey characteristics of the storms by combining several different available data sources, listsof storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks,solar wind in-situ measurements, neutron monitor data...

  8. Infrared response of the thermosphere-ionosphere system to geomagnetic storms

    Science.gov (United States)

    Thayer, J. P.; Mlynczak, M. G.; Hunt, L. A.; Russell, J. M., III

    2015-12-01

    For 14 years the SABER instrument on the NASA TIMED satellite has been observing the radiative cooling of the thermosphere-ionosphere system associated with infrared emission by nitric oxide (NO) and carbon dioxide (CO2). From these observations a very clear picture of fundamental processes that control the thermal structure above 100 km has emerged. The radiative cooling is modulated by variations in solar UV irradiance and geomagnetic effects. A pronounced solar cycle variation in both NO and CO2 cooling is observed, and CO2 cooling dominates during solar minimum. Radiative cooling in the current maximum peaked in December 2014, nine months after the sunspot peak. On average, solar ultraviolet irradiance provides about 70% of the energy that results in cooling by NO and the remaining 30% arises from geomagnetic processes. The relative roles of irradiance and geomagnetism vary strongly over a solar cycle. Of particular interest are the large, short-term increases in radiative cooling associated with intense geomagnetic storms. The large energy deposition heats the atmosphere and the infrared cooling increases non-linearly, helping the atmosphere to shed the storm energy and rapidly return to pre-storm conditions. This "natural thermostat" effect of infrared radiation will be shown in detail in this talk, as a function of latitude and altitude for a number of different geomagnetic storms. The relative roles of radiative cooling by NO and CO2 will also be investigated, to see if there is any storm-dependent preference. Finally, the sensitivity of the NO cooling to geomagnetic processes suggests that near real time observations of NO emission may serve as a forecasting tool for space weather. Increases in NO infrared emissions are associated with energy deposition and heating of the atmosphere. Observations of NO emission may then identify regions in which atmospheric drag is increasing, and thus may be a tool for now casting of drag for space operations.

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

    Science.gov (United States)

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

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

  10. New insights on geomagnetic storms from observations and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania K [Los Alamos National Laboratory

    2009-01-01

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

  11. Modelling of Geomagnetic Storm Effects in the Ionosphere of East Asia

    Institute of Scientific and Technical Information of China (English)

    G. A. Zherebtsov; O.M. Pirog; N.M. Polekh; E. B. Romanova; A.V. Tashchilin

    2005-01-01

    This paper presents simulated results of the ionospheric behavior during few geomagnetic storms,which were occurred in the different seasons. The numerical model for ionosphere-plasmasphere coupling was used to interpret the observed variation of ionosphere structure. Reasons why the positive storms are dominant in the winter whereas the negative ones are dominant in the summer season present the special interest for the mid-latitude ionosphere. A theoretical analysis of the processes controlling the ionospheric response to the geomagnetic storms has showed a good agreement between the simulated results and measurements, as well as the crucial role of the neutral composition variations to fit the calculated and the observed ionospheric parameters.

  12. Geomagnetic Storms and Acute Myocardial Infarctions Morbidity in Middle Latitudes

    Science.gov (United States)

    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

  13. Phase fluctuations of GPS signals and irregularities in the high latitude ionosphere during geomagnetic storm

    Science.gov (United States)

    Shagimuratov, I.; Chernouss, S.; Cherniak, Iu.; Efishov, I.; Filatov, M.; Tepenitsyna, N.

    2016-05-01

    In this report we analysed latitudinal occurrence of TEC fluctuations over Europe during October 2, 2013 geomagnetic storm. The data of GPS stations spaced in latitudinal range 68°-54° N over longitude of 20°E were involved in this investigation. The magnetograms of the IMAGE network and geomagnetic pulsations at Lovozero (68°02'N 35°00'W) and Sodankyla (67°22'N 26°38'W) observatories were used as indicator of auroral activity. During October 2, 2013 the strong geomagnetic field variations took place near 05 UT at auroral IMAGE network. We found good similarities between time development of substorm and fluctuations of GPS signals. The bay-like geomagnetic variations were followed by intensive phase fluctuations at auroral and subauroral stations. The strong short-term phase fluctuations were also found at mid-latitude Kaliningrad station near 05 UT that correspond to the maximal intense geomagnetic bay variations. This date confirms the equatorward expansion of the auroral oval. It brings in evidence also the storm time behavior of the irregularities oval obtained from multi-site GPS observations.

  14. Automatic prediction of solar flares and super geomagnetic storms

    Science.gov (United States)

    Song, Hui

    Space weather is the response of our space environment to the constantly changing Sun. As the new technology advances, mankind has become more and more dependent on space system, satellite-based services. A geomagnetic storm, a disturbance in Earth's magnetosphere, may produce many harmful effects on Earth. Solar flares and Coronal Mass Ejections (CMEs) are believed to be the major causes of geomagnetic storms. Thus, establishing a real time forecasting method for them is very important in space weather study. The topics covered in this dissertation are: the relationship between magnetic gradient and magnetic shear of solar active regions; the relationship between solar flare index and magnetic features of solar active regions; based on these relationships a statistical ordinal logistic regression model is developed to predict the probability of solar flare occurrences in the next 24 hours; and finally the relationship between magnetic structures of CME source regions and geomagnetic storms, in particular, the super storms when the D st index decreases below -200 nT is studied and proved to be able to predict those super storms. The results are briefly summarized as follows: (1) There is a significant correlation between magnetic gradient and magnetic shear of active region. Furthermore, compared with magnetic shear, magnetic gradient might be a better proxy to locate where a large flare occurs. It appears to be more accurate in identification of sources of X-class flares than M-class flares; (2) Flare index, defined by weighting the SXR flares, is proved to have positive correlation with three magnetic features of active region; (3) A statistical ordinal logistic regression model is proposed for solar flare prediction. The results are much better than those data published in the NASA/SDAC service, and comparable to the data provided by the NOAA/SEC complicated expert system. To our knowledge, this is the first time that logistic regression model has been applied

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

    Science.gov (United States)

    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

  16. Space weather and dangerous phenomena on the Earth: principles of great geomagnetic storms forcasting by online cosmic ray data

    Directory of Open Access Journals (Sweden)

    L. I. Dorman

    2005-11-01

    Full Text Available According to NOAA space weather scales, geomagnetic storms of scales G5 (3-h index of geomagnetic activity Kp=9, G4 (Kp=8 and G3 (Kp=7 are dangerous for satellites, aircrafts, and even for technology on the ground (influence on power systems, on spacecraft operations, on HF radio-communications and others. We show on the basis of statistical data, that these geomagnetic storms, mostly accompanied by cosmic ray (CR Forbush-decreases, are also dangerous for people's health on spacecraft and on the ground (increasing the rate of myocardial infarctions, brain strokes and car accident road traumas. To prevent these serious damages it is very important to forecast dangerous geomagnetic storms. Here we consider the principles of using CR measurements for this aim: to forecast at least 10-15h before the sudden commencement of great geomagnetic storms accompanied by Forbush-decreases, by using neutron monitor muon telescope worldwide network online hourly data. We show that for this forecast one may use the following features of CR intensity variations connected with geomagnetic storms accompanied by Forbush-decreases: 1 CR pre-increase, 2 CR pre-decrease, 3 CR fluctuations, 4 change in the 3-D CR anisotropy.

  17. Comparison of Dst Forecast Models for Intense Geomagnetic Storms

    Science.gov (United States)

    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 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 Dst <= 200 nT.

  18. Centennial to millennial geomagnetic field variations

    Directory of Open Access Journals (Sweden)

    Muscheler Raimund

    2012-06-01

    Full Text Available Reconstructions of the geomagnetic field in the past represent a useful tool not only to investigate the geodynamo process, but also to estimate the effect of geomagnetic shielding for any studies on cosmogenic radionuclides and galactic cosmic rays. A number of new millennial-scale geomagnetic field reconstructions have been published over the last years, based on improved global archeo- and paleomagnetic data compilations. Here we review several spherical harmonic models and compare their dipole field predictions to reconstructions based on virtual axial dipole moments and virtual geomagnetic poles. Dipole intensity estimates from cosmogenic radionuclide production records, with suitable filtering to minimise the solar influence, have also been included in the comparison to provide independent information about variations in the strength of the geomagnetic field. However, due to differences among geomagnetic models and between 14C and 10Be production records this comparison is fairly inconclusive with respect to multi-centennial variations. Different geomagnetic dipole tilt reconstructions agree well for much of the Holocene, but dipole moment estimates still differ substantially. Recent spherical harmonic models for the past 3 and 10 kyrs have improved considerably compared to earlier versions. Nevertheless at present we recommend to test if any interpretation depends on the choice of model.

  19. Interrelation of geomagnetic storms and earthquakes: Insight from lab experiments and field observations

    Science.gov (United States)

    Ruzhin, Yuri; Kamogawa, Masashi; Novikov, Victor

    Investigations of possible relations between variations of geomagnetic field and seismicity, including Sq-variations and geomagnetic storms, are overviewed and discussed. There are many papers demonstrating positive correlations between geomagnetic field variations and subsequent earthquake occurrence that allows to authors to talk about triggering impact on earthquake source provided by ionospheric disturbances [e.g., 1]. Nevertheless, there is another opinion on negligible impact of geomagnetic disturbances on the earthquake source supported by statistical analysis of correlation between variations of geomagnetic field and global and regional seismicity. In general, the both points of view on this problem are based on statistical research without detailed consideration of possible physical mechanisms which may be involved into the supposed earthquake triggering, or very rough estimations of possible increase of stresses in the faults under critical (near-to-failure) state were made. It is clear that verification of hypothesis of earthquake triggering by geomagnetic storms should be based on physical mechanisms of generation of additional stresses in the earthquake source or some secondary mechanisms resulted in change of the fault properties. Recently it was shown that the fluids may play very important role in the electromagnetic earthquake triggering [2], and the secondary triggering mechanism should be considered when the fluid migrating into the fault under electromagnetic action may provide fault weakening up to the earthquake triggering threshold. At the same time, depending on fault orientation, local hydrological structure of the crust around the fault, location of fluid reservoirs, etc. it may be possible that the fluid migration from the fault may provide the fault strengthening, and in this case the impact of variation of geomagnetic field may provide an opposite effect, and earthquake will not occur. In so doing, it is useless to apply only

  20. Quantitative Evaluation of Ionosphere Models for Reproducing Regional TEC During Geomagnetic Storms

    Science.gov (United States)

    Shim, J. S.; Kuznetsova, M.; Rastaetter, L.; Bilitza, D.; Codrescu, M.; Coster, A. J.; Emery, B.; Foster, B.; Fuller-Rowell, T. J.; Goncharenko, L. P.; Huba, J.; Mitchell, C. N.; Ridley, A. J.; Fedrizzi, M.; Scherliess, L.; Schunk, R. W.; Sojka, J. J.; Zhu, L.

    2015-12-01

    TEC (Total Electron Content) is one of the key parameters in description of the ionospheric variability that has influence on the accuracy of navigation and communication systems. To assess current TEC modeling capability of ionospheric models during geomagnetic storms and to establish a baseline against which future improvement can be compared, we quantified the ionospheric models' performance by comparing modeled vertical TEC values with ground-based GPS TEC measurements and Multi-Instrument Data Analysis System (MIDAS) TEC. The comparison focused on North America and Europe sectors during selected two storm events: 2006 AGU storm (14-15 Dec. 2006) and 2013 March storm (17-19 Mar. 2013). The ionospheric models used for this study range from empirical to physics-based, and physics-based data assimilation models. We investigated spatial and temporal variations of TEC during the storms. In addition, we considered several parameters to quantify storm impacts on TEC: TEC changes compared to quiet time, rate of TEC change, and maximum increase/decrease during the storms. In this presentation, we focus on preliminary results of the comparison of the models performance in reproducing the storm-time TEC variations using the parameters and skill scores. This study has been supported by the Community Coordinated Modeling Center (CCMC) at the Goddard Space Flight Center. Model outputs and observational data used for the study will be permanently posted at the CCMC website (http://ccmc.gsfc.nasa.gov) for the space science communities to use.

  1. Storm surge variational assimilation model

    Directory of Open Access Journals (Sweden)

    Shi-li HUANG

    2010-06-01

    Full Text Available To eliminate errors caused by uncertainty of parameters and further improve capability of storm surge forecasting, the variational data assimilation method is applied to the storm surge model based on unstructured grid with high spatial resolution. The method can effectively improve the forecasting accuracy of storm surge induced by typhoon through controlling wind drag force coefficient parameter. The model is first theoretically validated with synthetic data. Then, the real storm surge process induced by the TC 0515 typhoon is forecasted by the variational data assimilation model, and results show the feasibility of practical application.

  2. Geomagnetic storms link to the mortality rate in the Smolyan region for the period 1988--2009

    Science.gov (United States)

    Simeonova, Siyka G. 1; Georgieva, Radostina C. 2; Dimitrova, Boryana H. 2; Slavcheva, Radka G. 2; Kerimova, Bojena P. 2; Georgiev, Tsvetan B. 34

    We present correlations and trends of 10 parameters of annual mortality rate (1 to common mortality rate, 5 to cardiovascular reasons and 4 to "accidental" reasons (car accidents, suicides, infections)) with respect to 6 parameters of annual solar and geomagnetic activity (Wolf index, number of geomagnetic storms, duration of the storms, amplitude of the storms). During the period of observation, characterized by a 3-4-fold decrease of the mean geomagnetic activity (in terms of the number and the duration of the storms) and with a strong variations of the amplitude of the storms (about an almost constant mean values for the period), there is a 1.3-fold decrease in the urban population, a 1.5-fold increase of the common mortality rate, a 1.8-fold increase of the cardiovascular mortality rate and a 1.1-fold decrease of the "accidental" mortality rates. During the years 2003-2005 we observe about 2-fold temporary increase in the storm amplitudes. During the years 2007-2008, characterized by extremely low geomagnetic activity, we observe a surprising temporary increase of the common and the cardiovascular mortality rates 1.1 and 1.3-fold, respectively (Figures 1-4). We point out 3 main results. (1) The available data shows notable increase in the mortality rates while there is generally a decrease of the solar or geomagnetic activity during the studied period (Figures 5-9). We explain this anti-correlation with the domination of the increasing mortality rates as an effect of the advance in the mean age of the population (due to immigration of young people and decrease of new-borns), hiding an eventual display of the solar and geomagnetic influence on the mortality rates. Using this data we can not reveal influence of the long-time (10-20 years) change of the average solar and geomagnetic activity on the mortality rate. (2) Excluding the unusual years 2007 and 2008, we establish that with respect to the years with low geomagnetic activity (1993, 1995, 1996, 1999), in

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

    Indian Academy of Sciences (India)

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

    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.

  4. Large Geomagnetic Storms Associated with Limb Halo Coronal Mass Ejections

    CERN Document Server

    Gopalswamy, Nat; Xie, Hong; Akiyama, Sachiko; Makela, Pertti

    2009-01-01

    Solar cycle 23 witnessed the observation of hundreds of halo coronal mass ejections (CMEs), thanks to the high dynamic range and extended field of view of the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. More than two thirds of halo CMEs originating on the front side of the Sun have been found to be geoeffective (Dst = 45deg) have a 20% shorter delay time on the average. It was suggested that the geomagnetic storms due to limb halos must be due to the sheath portion of the interplanetary CMEs (ICMEs) so that the shorter delay time can be accounted for. We confirm this suggestion by examining the sheath and ejecta portions of ICMEs from Wind and ACE data that correspond to the limb halos. Detailed examination showed that three pairs of limb halos were interacting events. Geomagnetic storms following five limb halos were actually produced by other disk halos. The storms followed by four isolated limb halos and the ones associated with interact...

  5. Artificial reproduction of magnetic fields produced by a natural geomagnetic storm increases systolic blood pressure in rats

    Science.gov (United States)

    Martínez-Bretón, J. L.; Mendoza, B.; Miranda-Anaya, M.; Durán, P.; Flores-Chávez, P. L.

    2016-04-01

    The incidence of geomagnetic storms may be associated with changes in circulatory physiology. The way in which the natural variations of the geomagnetic field due to solar activity affects the blood pressure are poorly understood and require further study in controlled experimental designs in animal models. In the present study, we tested whether the systolic arterial pressure (AP) in adult rats is affected by simulated magnetic fields resembling the natural changes of a geomagnetic storm. We exposed adult rats to a linear magnetic profile that simulates the average changes associated to some well-known geomagnetic storm phases: the sudden commencement and principal phase. Magnetic stimulus was provided by a coil inductor and regulated by a microcontroller. The experiments were conducted in the electromagnetically isolated environment of a semi-anechoic chamber. After exposure, AP was determined with a non-invasive method through the pulse on the rat's tail. Animals were used as their own control. Our results indicate that there was no statistically significant effect in AP when the artificial profile was applied, neither in the sudden commencement nor in the principal phases. However, during the experimental period, a natural geomagnetic storm occurred, and we did observe statistically significant AP increase during the sudden commencement phase. Furthermore, when this storm phase was artificially replicated with a non-linear profile, we noticed a 7 to 9 % increase of the rats' AP in relation to a reference value. We suggested that the changes in the geomagnetic field associated with a geomagnetic storm in its first day could produce a measurable and reproducible physiological response in AP.

  6. Artificial reproduction of magnetic fields produced by a natural geomagnetic storm increases systolic blood pressure in rats

    Science.gov (United States)

    Martínez-Bretón, J. L.; Mendoza, B.; Miranda-Anaya, M.; Durán, P.; Flores-Chávez, P. L.

    2016-11-01

    The incidence of geomagnetic storms may be associated with changes in circulatory physiology. The way in which the natural variations of the geomagnetic field due to solar activity affects the blood pressure are poorly understood and require further study in controlled experimental designs in animal models. In the present study, we tested whether the systolic arterial pressure (AP) in adult rats is affected by simulated magnetic fields resembling the natural changes of a geomagnetic storm. We exposed adult rats to a linear magnetic profile that simulates the average changes associated to some well-known geomagnetic storm phases: the sudden commencement and principal phase. Magnetic stimulus was provided by a coil inductor and regulated by a microcontroller. The experiments were conducted in the electromagnetically isolated environment of a semi-anechoic chamber. After exposure, AP was determined with a non-invasive method through the pulse on the rat's tail. Animals were used as their own control. Our results indicate that there was no statistically significant effect in AP when the artificial profile was applied, neither in the sudden commencement nor in the principal phases. However, during the experimental period, a natural geomagnetic storm occurred, and we did observe statistically significant AP increase during the sudden commencement phase. Furthermore, when this storm phase was artificially replicated with a non-linear profile, we noticed a 7 to 9 % increase of the rats' AP in relation to a reference value. We suggested that the changes in the geomagnetic field associated with a geomagnetic storm in its first day could produce a measurable and reproducible physiological response in AP.

  7. Geomagnetically Induced Currents in the Irish Power Network during Geomagnetic Storms

    CERN Document Server

    Blake, Seán P; Jones, Alan G; Hogg, Colin; Campanyà, Joan; Beggan, Ciarán; Thomson, Alan W P; Kelly, Gemma S; Bell, David

    2016-01-01

    Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They occur in power transmission networks and are known to have adverse effects in both high and mid-latitude countries. Here, we study GICs in the Irish power transmission network (geomagnetic latitude 54.7--58.5$^{\\circ}$ N) during five geomagnetic storms (06-07 March 2016, 20-21 December 2015, 17-18 March 2015, 29-31 October 2003 and 13-14 March 1989). We simulate electric fields using a plane wave method together with two ground resistivity models, one of which is derived from magnetotelluric measurements (MT model). We then calculate GICs in the 220, 275 and 400~kV transmission network. During the largest of the storm periods studied, the peak electric field was calculated to be as large as 3.8~V~km\\textsuperscript{-1}, with associated GICs of up to 23~A using our MT model. Using our homogenous resistivity model, those peak values were 1.46~V~km\\textsuperscript{-1} and 25.8~A. We find that three 400 and 275~kV subs...

  8. Geomagnetically induced currents in the Irish power network during geomagnetic storms

    Science.gov (United States)

    Blake, Seán. P.; Gallagher, Peter T.; McCauley, Joe; Jones, Alan G.; Hogg, Colin; Campanyà, Joan; Beggan, Ciarán. D.; Thomson, Alan W. P.; Kelly, Gemma S.; Bell, David

    2016-12-01

    Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They occur in power transmission networks and are known to have adverse effects in both high-latitude and midlatitude countries. Here we study GICs in the Irish power transmission network (geomagnetic latitude 54.7-58.5°N) during five geomagnetic storms (6-7 March 2016, 20-21 December 2015, 17-18 March 2015, 29-31 October 2003, and 13-14 March 1989). We simulate electric fields using a plane wave method together with two ground resistivity models, one of which is derived from magnetotelluric measurements (magnetotelluric (MT) model). We then calculate GICs in the 220, 275, and 400 kV transmission network. During the largest of the storm periods studied, the peak electric field was calculated to be as large as 3.8 V km-1, with associated GICs of up to 23 A using our MT model. Using our homogenous resistivity model, those peak values were 1.46 V km-1 and 25.8 A. We find that three 400 and 275 kV substations are the most likely locations for the Irish transformers to experience large GICs.

  9. Enhancement in Surface Atmospheric Pressure Variability Associated with a Major Geomagnetic Storm

    CERN Document Server

    Selvam, A M; Athale, S U; Tinmaker, M I R

    1998-01-01

    Observational studies indicate that there is a close association between geomagnetic storm and meteorological parameters. Geomagnetic field lines follow closely the isobars of surface pressure . A Physical mechanism linking upper atmospheric geomagnetic storm disturbances with tropospheric weather has been proposed by the author and her group where it is postulated that vertical mixing by turbulent eddy fluctuations results in the net transport upward of positive charges originating from lower levels accompanied simultaneously by downward flow of negative charges from higher levels. The present study reports enhancement of high frequency (<15 days period) fluctuations in daily surface pressure during March 1989 in association with major geomagnetic storm (Ap index = 246) on 13 march 1989.

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

    Science.gov (United States)

    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).

  11. Modeling geomagnetic storms on prompt and diffusive time scales

    Science.gov (United States)

    Li, Zhao

    The discovery of the Van Allen radiation belts in the 1958 was the first major discovery of the Space Age. There are two belts of energetic particles. The inner belt is very stable, but the outer belt is extremely variable, especially during geomagnetic storms. As the energetic particles are hazardous to spacecraft, understanding the source of these particles and their dynamic behavior driven by solar activity has great practical importance. In this thesis, the effects of magnetic storms on the evolution of the electron radiation belts, in particular the outer zone, is studied using two types of numerical simulation: radial diffusion and magnetohydrodynamics (MHD) test-particle simulation. A radial diffusion code has been developed at Dartmouth, applying satellite measurements to model flux as an outer boundary condition, exploring several options for the diffusion coefficient and electron loss time. Electron phase space density is analyzed for July 2004 coronal mass ejection (CME) driven storms and March-April 2008 co-rotating interaction region (CIR) driven storms, and compared with Global Positioning System (GPS) satellite measurements within 5 degrees of the magnetic equator at L=4.16. A case study of a month-long interval in the Van Allen Probes satellite era, March 2013, confirms that electron phase space density is well described by radial diffusion for the whole month at low first invariant 0.6 MeV by an order of magnitude over 24 hours as observed.

  12. Development of KASI Geomagnetic Storm Forecast System using Coronagraph Data

    Science.gov (United States)

    Baek, Ji-Hye; Choi, SeongHwan; Park, Jongyeob; Kim, Roksoon; Kim, Sujin; Kim, Jihun

    2017-08-01

    We present Korea Astronomy and Space Science Institute (KASI) Geomagnetic Storm Forecast System. The aim of the system is to calculate the CME arrival time and predict the geoeffectiveness of the CME. To implement the system, we use the Large Angle and Spectrometric Coronagraph (LASCO) C2 and C3 data, the HMI magnetogram data of Solar Dynamics Observatory(SDO), and CACTUS CME list. The system consists of servers, which are to download, process, and publish data, data handling programs and web service. We apply an image differencing technique on LASCO data to determine speed and earthward direction parameters of CMEs. KASI Geomagnetic Storm Forecast Model has installed and being tested at Community Coordinated Modeling Center (CCMC) of NASA/GSFC. We expect that users can predict CME arrival time and geoeffectiveness of the CME easily and fast using the system. In order to improve the forecast performance of the system, we plan to incorporate advanced coronagraph data which will be developed and installed on ISS by KASI and NASA in collaboration.

  13. Geomagnetic storms, Forbush decreases of cosmic rays and total ozone at northern higher middle latitudes

    Science.gov (United States)

    Laštovička, Jan; Križan, Peter

    2005-01-01

    Space weather affects the Earth's atmosphere in many ways and through various phenomena. Among them, geomagnetic storms and the variability of the galactic cosmic ray flux belong to the most important ones as for the lower atmosphere. Here, we summarize our previous results on the effects of strong geomagnetic storms and strong Forbush decreases of galactic cosmic rays on the total ozone at the northern higher middle latitudes, and complete them with investigations of effects of geomagnetic storms not accompanied by Forbush decreases. The effects of strong geomagnetic storms and Forbush decreases occur only in the winter part of the year, under the high solar activity and the E-phase of QBO (E-max) conditions. The effects of storms seem to be a redistribution of ozone as a consequence of storm-related changes of circulation. No event contradicts the idea that the Forbush decreases are responsible for effects of geomagnetic storms on the lower atmosphere (troposphere and lower stratosphere) including total ozone. However, under the E-max conditions in the winter part of the year, only several Forbush decreases without geomagnetic storms and only one geomagnetic storm without the Forbush decrease occurred over more than 20 years.

  14. Active experiments in the ionosphere and geomagnetic field variations

    Science.gov (United States)

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

    2014-11-01

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

  15. Interplanetary magnetic field and geomagnetic Dst variations.

    Science.gov (United States)

    Patel, V. L.; Desai, U. D.

    1973-01-01

    The interplanetary magnetic field has been shown to influence the ring current field represented by Dst. Explorer 28 hourly magnetic field observations have been used with the hourly Dst values. The moderate geomagnetic storms of 60 gammas and quiet-time fluctuations of 10 to 30 gammas are correlated with the north to south change of the interplanetary field component perpendicular to the ecliptic. This change in the interplanetary field occurs one to three hours earlier than the corresponding change in the Dst field.

  16. Study of the mid-latitude ionospheric response to geomagnetic storms in the European region

    Science.gov (United States)

    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.

  17. Response of the middle atmosphere to the geomagnetic storm of November 2004

    Science.gov (United States)

    Hocke, Klemens

    2017-02-01

    Ozone and temperature profiles of the satellite microwave limb sounder Aura/MLS are used for the derivation of the middle atmospheric response to the geomagnetic superstorm of 9 November 2004. We find a destruction of the tertiary ozone layer at 0.022 hPa (77 km) in the northern winter hemisphere lasting for about one week. This effect is surely due to the solar proton event (SPE) of November 2004. At the same time, the zonal mean temperature is enhanced by 5-10 K in the northern polar mesosphere. On the other hand, the zonal mean temperature is decreased by 5-10 K in the northern polar stratosphere. We do not think that the strong temperature perturbations are directly related to the SPE. It seems that the polar vortex was moved by the geomagnetic storm, and this vortex movement caused the strong temperature variations in the zonal mean. However, internal variability of temperature in the polar middle atmosphere in winter without any significant link to the geomagnetic storm cannot be excluded.

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

    Science.gov (United States)

    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.

  19. Driving Plasmaspheric Electron Density Simulations During Geomagnetic Storms

    Science.gov (United States)

    De Pascuale, S.; Kletzing, C.; Jordanova, V.; Goldstein, J.; Wygant, J. R.; Thaller, S. A.

    2015-12-01

    We test global convection electric field models driving plasmaspheric electron density simulations (RAM-CPL) during geomagnetic storms with in situ measurements provided by the Van Allen Probes (RBSP). RAM-CPL is the cold plasma component of the ring-current atmosphere interactions suite (RAM-SCB) and describes the evolution of plasma density in the magnetic equatorial plane near Earth. Geomagnetic events observed by the RBSP satellites in different magnetic local time (MLT) sectors enable a comparison of local asymmetries in the input electric field and output densities of these simulations. Using a fluid MHD approach, RAM-CPL reproduces core plasmaspheric densities (L<4) to less than 1 order of magnitude difference. Approximately 80% of plasmapause crossings, defined by a low-density threshold, are reproduced to within a mean radial difference of 0.6 L. RAM-CPL, in conjunction with a best-fit driver, can be used in other studies as an asset to predict density conditions in locations distant from RBSP orbits of interest.

  20. Enhancement of Terrestrial Diffuse X-ray Emission Associated With Coronal Mass Ejection and Geomagnetic Storm

    CERN Document Server

    Ezoe, Yuichiro; Yoshitake, Hiroshi; Mitsuda, Kazuhisa; Terada, Naoki; Oishi, Shihoko; Ohashi, Takaya

    2011-01-01

    We present an analysis of a Suzaku observation taken during the geomagnetic storm of 2005 August 23-24. We found time variation of diffuse soft X-ray emission when a coronal mass ejection hit Earth and caused a geomagnetic storm. The diffuse emission consists of fluorescent scattering of solar X-rays and exospheric solarwind charge exchange. The former is characterized by a neutral oxygen emission line due to strong heating of the upper atmosphere during the storm time, while the latter is dominated by a sum of C V, C VI, N VI, N VII, O VII, and O VIII emission lines due to the enhanced solar wind flux in the vicinity of the exosphere. Using the solar wind data taken with the ACE and WIND satellites,a time correlation between the solar wind and the strong O VII line flux were investigated. We estimated necessary column densities for the solar X-ray scattering and exospheric SWCX. From these results, we argue that a part of the solar wind ions enter inside the magnetosphere and cause the SWCX reaction.

  1. Geographical localisation of the geomagnetic secular variation

    OpenAIRE

    Aubert, Julien; Finlay, Chris; Olsen, Nils

    2013-01-01

    Directly observed changes in Earth’s magnetic field occur most prominently at low latitudes beneath the Atlantic hemisphere, while the Pacific is comparatively quiet. This striking hemispheric asymmetry in geomagnetic secular variation is a consequence of the geographical localisation of intense, westward moving, magnetic flux patches at the core surface. Despite its successes in explaining the main morphological properties of Earth’s magnetic field, self-consistent numerical modelling of the...

  2. Solar and Interplanetary Disturbances causing Moderate Geomagnetic Storms

    Indian Academy of Sciences (India)

    Santosh Kumar; M. P. Yadav; Amita Raizada

    2008-03-01

    The effect of solar and interplanetary disturbances on geomagnetospheric conditions leading to 121 moderate geomagnetic storms (MGS) have been investigated using the neutron monitor, solar geophysical and interplanetary data during the period 1978–99. Further, the duration of recovery phase has been observed to be greater than the duration of main phase in most of the cases of MGS. It has further been noted that Ap-index increases on sudden storm commencement (SSC) day than its previous day value and acquires maximum value on the day of maximum solar activity. Generally, the decrease in cosmic ray (CR) intensity and Dst begins few hours earlier than the occurrence of MGS at Earth. Furthermore, negative Bz pointing southward plays a key causal role in the occurrence of MGS and the magnitude and the duration of Bz and Bav also play a significant role in the development of MGS. The solar features H, X-ray solar flares and active prominences and disappearing filaments (APDFs) which have occurred within lower helio-latitudinal/helio-longitudinal zones produce larger number of MGS. Solar flares seem to be the major cause for producing MGS.

  3. Erosion of the inner magnetosphere during geomagnetic storms

    Directory of Open Access Journals (Sweden)

    E. Y. Feshchenko

    Full Text Available Using the empirical magnetic field model dependent on the Dst index and solar wind dynamic pressure, we calculated the behaviour of the contour B = Bs in the equatorial plane of the magnetosphere where Bs is the magnetic field in the subsolar point at the magnetopause. The inner domain of the magnetosphere outlined by this contour contains the bulk of geomagnetically trapped particles. During quiet time the boundary of the inner magnetosphere passes at the distance ~10 RE at noon and at ~7 RE at midnight. During very intense storms this distance can be reduced to 4–5 RE for all MLT. The calculation results agree well with the satellite measurements of the magnetopause location during storms. The ionospheric projection of the B = Bs contour calculated with the Euler potential technique is close to the equatorward edge of the auroral oval.

  4. Thermospheric density estimation and responses to the March 2013 geomagnetic storm from GRACE GPS-determined precise orbits

    Science.gov (United States)

    Calabia, Andres; Jin, Shuanggen

    2017-02-01

    The thermospheric mass density variations and the thermosphere-ionosphere coupling during geomagnetic storms are not clear due to lack of observables and large uncertainty in the models. Although accelerometers on-board Low-Orbit-Earth (LEO) satellites can measure non-gravitational accelerations and derive thermospheric mass density variations with unprecedented details, their measurements are not always available (e.g., for the March 2013 geomagnetic storm). In order to cover accelerometer data gaps of Gravity Recovery and Climate Experiment (GRACE), we estimate thermospheric mass densities from numerical derivation of GRACE determined precise orbit ephemeris (POE) for the period 2011-2016. Our results show good correlation with accelerometer-based mass densities, and a better estimation than the NRLMSISE00 empirical model. Furthermore, we statistically analyze the differences to accelerometer-based densities, and study the March 2013 geomagnetic storm response. The thermospheric density enhancements at the polar regions on 17 March 2013 are clearly represented by POE-based measurements. Although our results show density variations better correlate with Dst and k-derived geomagnetic indices, the auroral electroject activity index AE as well as the merging electric field Em picture better agreement at high latitude for the March 2013 geomagnetic storm. On the other side, low-latitude variations are better represented with the Dst index. With the increasing resolution and accuracy of Precise Orbit Determination (POD) products and LEO satellites, the straightforward technique of determining non-gravitational accelerations and thermospheric mass densities through numerical differentiation of POE promises potentially good applications for the upper atmosphere research community.

  5. The ionospheric response in the Brazilian sector during the super geomagnetic storm on 20 November 2003

    Science.gov (United States)

    Becker-Guedes, F.; Sahai, Y.; Fagundes, P. R.; Espinoza, E. S.; Pillat, V. G.; Lima, W. L. C.; Basu, Su.; Basu, Sa.; Otsuka, Y.; Shiokawa, K.; MacKenzie, E. M.; Pi, X.; Bittencourt, J. A.

    2007-05-01

    A very intense geomagnetic storm (superstorm) began with storm sudden commencement (SSC) at 08:03 UT on 20 November 2003, as a result of the coronal mass ejection (CME) by sunspot 484 hurled into space on 18 November 2003. The geomagnetic storm attained |Dst|max=472 nT at 20:00 UT (20 November). In this paper we present the simultaneous ionospheric sounding observations, using the Canadian Advanced Digital Ionosondes (CADIs), carried out from Palmas (PAL; 10.2° S, 48.2° W; dip latitude 5.5° S; a near equatorial station) and São José dos Campos (SJC; 23.2° S, 45.9° W; dip latitude 17.6° S; station located under the crest of equatorial ionospheric anomaly), Brazil. In addition, total electron content (TEC) measurements from several GPS receiving stations in the Brazilian sector during this storm are presented. The simultaneous ionospheric sounding observations carried out at SJC and PAL, and TEC observations on 3 consecutive days viz., 19 November (quiet), 20 November (disturbed) and 21 November (recovery phase) are presented. Salient features from the ionospheric observations in the Brazilian sector during the superstorm are discussed. The difference in the observed ionospheric response at the two stations (PAL and SJC) is considerable. This is not surprising given that PAL is close to the magnetic equator and SJC is near the crest of the equatorial ionospheric anomaly (EIA). It should be pointed out that soon after the SSC (about 4 h later), the F-region critical frequency (foF2), the F-region peak height (hpF2), and variations of virtual heights at different frequencies (iso-frequency plots) all show wavelike oscillations of the F-region during daytime at both the ionospheric sounding stations. Unusual rapid uplifting of F-region at PAL was observed during both the main and recovery phases of the storm.

  6. RBSPICE measurement of ion loss during the 2015 March storm: Adiabatic response to the geomagnetic field change

    Science.gov (United States)

    Soto-Chavez, A. R.; Lanzerotti, L. J.; Gerrard, A.; Kim, H.; Bortnik, J.; Manweiler, J. W.

    2016-10-01

    A strongly energy-dependent ring current ion loss was measured by the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument on the Van Allen Probes A spacecraft in the local evening sector during the 17 March 2015 geomagnetic storm. The ion loss is found to be energy dependent where only ions with energies measured above ˜ 150 keV have a significant drop in intensity. At these energies the ion dynamics are principally controlled by variations of the geomagnetic field which, during magnetic storms, exhibits large-scale variations on time scales from minutes to hours. Here we show that starting from ˜19:10 UTC on 17 March the geomagnetic field increased from 220 to 260 nT on a time scale of about an hour as captured by RBSPICE-A close to spacecraft apogee, L = 6.1 and magnetic local time (MLT) = 21.85 h (GSM coordinates X =- 4.89, Y = 3.00, and Z =- 0.73). We demonstrate the relationship between this large geomagnetic field increase and the dropouts of the ≳ 150 keV ring current ions.

  7. GEOMAGNETIC STORMS AND CARRINGTON EVENT = TEMPESTADES GEOMAGNETICAS E O EVENTO CARRINGTON

    National Research Council Canada - National Science Library

    Gerson Antonio Santarine; Roberto Naves Domingos

    2014-01-01

    .... If Earth is directly in line sight of a coronal blast, a shock wave of energetic charged particles from the star will cause a geomagnetic storm due to its abrupt interaction with terrestrial magnetic field...

  8. Effects of orbit progression on the radiation exposures from solar proton fluxes in low Earth orbit under geomagnetic storm conditions.

    Science.gov (United States)

    Nealy, J E; Wilson, J W; Shea, M A; Smart, D F

    1996-01-01

    The present study examines the effects of orbit progression on the exposures within a Space Station Freedom module in a 51.6-degree inclined orbit at 450 km. The storm evolution is modeled after the November 1960 event, and the solar proton flux evolution is taken from the August 1972 solar proton event. The effects of a strong magnetic shock, such as was observed during the October 1989 event, is also modeled. The statistics on hourly average storm fields for the last forty years reveal that the largest geomagnetic storms approach a Dst value of -500 nanotesla at the storm peak. Similarly, one of the largest satellite-measured proton flux (> 10 MeV) for space exposures is the event of August 1972. The effects of orbit progression (advance of the line of nodes) is examined for the above conditions to study the variation of exposures under differing times of occurrence of the solar proton peak intensity, attainment of geomagnetic storm maximum, and the location of the line of nodes of the last geomagnetically protected orbit. The impact of the inherent inhomogeneity of the space station module is examined as a limiting factor on exposure with regard to the need of additional parasitic shielding.

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

    Science.gov (United States)

    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.

  10. Multi-Instrument Observations of a Geomagnetic Storm and its Effects on the Arctic Ionosphere: A Case Study of the 19 February 2014 Storm

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga;

    2017-01-01

    We present a multi-instrumented approach for the analysis of the Arctic ionosphere during the 19 February 2014 highly complex, multiphase geomagnetic storm, which had the largest impact on the disturbance storm-time (Dst) index that year. The geomagnetic storm was the result of two powerful Earth...

  11. Accurate and Timely Forecasting of CME-Driven Geomagnetic Storms

    Science.gov (United States)

    Chen, J.; Kunkel, V.; Skov, T. M.

    2015-12-01

    Wide-spread and severe geomagnetic storms are primarily caused by theejecta of coronal mass ejections (CMEs) that impose long durations ofstrong southward interplanetary magnetic field (IMF) on themagnetosphere, the duration and magnitude of the southward IMF (Bs)being the main determinants of geoeffectiveness. Another importantquantity to forecast is the arrival time of the expected geoeffectiveCME ejecta. In order to accurately forecast these quantities in atimely manner (say, 24--48 hours of advance warning time), it isnecessary to calculate the evolving CME ejecta---its structure andmagnetic field vector in three dimensions---using remote sensing solardata alone. We discuss a method based on the validated erupting fluxrope (EFR) model of CME dynamics. It has been shown using STEREO datathat the model can calculate the correct size, magnetic field, and theplasma parameters of a CME ejecta detected at 1 AU, using the observedCME position-time data alone as input (Kunkel and Chen 2010). Onedisparity is in the arrival time, which is attributed to thesimplified geometry of circular toroidal axis of the CME flux rope.Accordingly, the model has been extended to self-consistently includethe transverse expansion of the flux rope (Kunkel 2012; Kunkel andChen 2015). We show that the extended formulation provides a betterprediction of arrival time even if the CME apex does not propagatedirectly toward the earth. We apply the new method to a number of CMEevents and compare predicted flux ropes at 1 AU to the observed ejectastructures inferred from in situ magnetic and plasma data. The EFRmodel also predicts the asymptotic ambient solar wind speed (Vsw) foreach event, which has not been validated yet. The predicted Vswvalues are tested using the ENLIL model. We discuss the minimum andsufficient required input data for an operational forecasting systemfor predicting the drivers of large geomagnetic storms.Kunkel, V., and Chen, J., ApJ Lett, 715, L80, 2010. Kunkel, V., Ph

  12. Thermospheric recovery during the 5 April 2010 geomagnetic storm

    Science.gov (United States)

    Sheng, Cheng; Lu, Gang; Solomon, Stanley C.; Wang, Wenbin; Doornbos, Eelco; Hunt, Linda A.; Mlynczak, Martin G.

    2017-04-01

    Thermospheric temperature and density recovery during the 5 April 2010 geomagnetic storm has been investigated in this study. Neutral density recovery as revealed by Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) simulations was slower than observations from GOCE, CHAMP, and GRACE satellites, suggesting that the cooling processes may not be fully represented in the model. The NO radiative cooling rate in TIEGCM was also compared with TIMED/SABER measurements along satellite orbits during this storm period. It was found that the model overestimated the NO cooling rate at low latitudes and underestimated it at high latitudes. The effects of particle precipitation on NO number density and NO cooling rate at high latitudes were examined in detail. Model experiments showed that while NO number density and NO cooling rate do change with different specifications of the characteristic energy of auroral precipitating electrons, neutral temperature and density recovery remain more or less the same. The reaction rates of key NO chemistry were tested as well, and the NO number density between 110 and 150 km was found to be very sensitive to the reaction rate of N(2D) + O2 → NO + O. A temperature-dependent reaction rate for this reaction proposed by Duff et al. (2003) brought the TIEGCM NO cooling rate at high latitudes closer to the SABER observations. With the temperature-dependent reaction rate, the neutral density recovery time became quite close to the observations in the high-latitude Southern Hemisphere. But model-data discrepancies still exist at low latitudes and in the Northern Hemisphere, which calls for further investigation.

  13. Multi-Instrument Observations of Geomagnetic Storms in the Arctic Ionosphere

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga;

    We present a multi-instrumented approach for the analysis of the Arctic ionosphere during the 19 February 2014 highly complex, multiphase geomagnetic storm. The geomagnetic storm was the result of two powerful and subsequent Earth-directed coronal mass ejections (CMEs). The first one was launched...... from the solar corona on 16 February and the second one on 18 February. We focus on effects of such solar-originated geomagnetic disturbances on the high latitude ionosphere because our present understanding of the fundamental ionospheric processes – particularly during perturbed times – in this region...

  14. Major Geomagnetic Storms (Dst less than or equal to -100 nT) Generated by Corotating Interaction Regions

    Science.gov (United States)

    Richardson, I. G.; Webb, D. F.; Zhang, J.; Berdichevsky, B. D.; Biesecker, D. A.; Kasper, J. C.; Kataoka, R.; Steinberg, J. T.; Thompson, B. J.; Wu, C.-C.; Zhukov, A. N.

    2006-01-01

    Seventy-nine major geomagnetic storms (minimum Dst less than or equal to -100 nT) observed in 1996 to 2004 were the focus of a Living with a Star Coordinated Data-Analysis Workshop (CDAW) in March, 2005. In 9 cases, the storm driver appears to have been purely a corotating interaction region (CIR) without any contribution from coronal mass ejection-related material (interplanetary coronal mass ejections, ICMEs). These storms were generated by structures within CIRs located both before and/or after the stream interface that included persistently southward magnetic fields for intervals of several hours. We compare their geomagnetic effects with those of 159 CIRs observed during 1996 - 2005. The major storms form the extreme tail of a continuous distribution of CIR geoeffectiveness which peaks at Dst approx. -40 nT but is subject to a prominent seasonal variation of - 40 nT which is ordered by the spring and fall equinoxes and the solar wind magnetic field direction towards or away from the Sun. The O'Brien and McPherron [2000] equations, which estimate Dst by integrating the incident solar wind electric field and incorporating a ring current loss term, largely account for the variation in storm size. They tend to underestimate the size of the larger CIR-associated storms by Dst approx. 20 nT. This suggests that injection into the ring current may be more efficient than expected in such storms. Four of the nine major storms in 1996 - 2004 occurred during a period of less than three solar rotations in September - November, 2002, also the time of maximum mean IMF and solar magnetic field intensity during the current solar cycle. The maximum CIR-storm strength found in our sample of events, plus additional 23 probable CIR-associated Dst less than or equal to -100 nT storms in 1972 - 1995, is (Dst = -161 nT). This is consistent with the maximum storm strength (Dst approx. -180 nT) expected from the O'Brien and McPherron equations for the typical range of solar wind

  15. NM-MT network and space dangerous phenomena, 1. Principles of major geomagnetic storms forecasting

    Science.gov (United States)

    Dorman, L.; Pustil Nik, L.; Sternlieb, A.; Zukerman, I.

    According to NOAA Space Weather Scales, geomagnetic storms of scales G5 (3- hour index of geomagnetic activity Kp=9), G4 (Kp=8) and G3 (Kp=7) are dangerous for people technology and health (influence on power systems, on spacecraft operations, on HF radio-communications and others). To prevent these serious damages will be very important to forecast dangerous geomagnetic storms. In many papers it was shown that in principle for this forecasting can be used data on CR intensity and CR anisotropy changing before SC of major geomagnetic storms accompanied by sufficient Forbush-decreases (e.g., Dorman et al., 1995, 1999). In this paper we consider over 100 major geomagnetic storms and for each case we analyze hourly data of many NM for 8 days with SC in the 4-st day of 8 days period (so before SC we have at least 3 full days). We- determine what part of major geomagnetic storms is accompanied CR intensity and CR anisotropy changing before SC, and what part of major geomagnetic storms does not show any features what can be used for forecasting. We estimate also how these parts depend from the index of geomagnetic activity Kp. This research is partly supported by the INTAS grant 00-0810. REFERENCES: Dorman L.I., et al. "Cosmic-ray forecasting features for big Forbush-decreases". Nuclear Physics B, 49A, 136-144 (1995). L.I.Dorman, et al, "Cosmic ray Forbush-decrease as indicators of space dangerous phenomenon and possible use of cosmic ray data for their prediction", Proc. of 26-th Intern. Cosmic Ray Conference, Salt Lake City, 6, 476-479 (1999).

  16. Low latitude ionospheric effects near longitude 120°E during the great geomagnetic storm of July 2000

    Institute of Scientific and Technical Information of China (English)

    LIU; Libo(刘立波); WAN; Weixing(万卫星); NING; Baiqi(宁百齐); YUAN; Hong(袁洪); Liu; J.Y.

    2002-01-01

    A great geomagnetic storm occurred on July 15/16, 2000 with a minimum value of about -300 nT in Dst index. Collecting digisonde data from ionospheric stations at Chungli, Wuhan, Kokubunji and Anyang, the ionospheric responses at the low latitudes near longitude 120(E during this storm are analyzed in this paper. There was a strong negative phase storm at low latitudes on July 16. The G-condition in the ionograms was clearly seen on the early first day after the commencement of geomagnetic storm. Those were considered to be caused by the storm-induced increase in the concentration ratios of neutral molecular O2 or N2 to atom O. On July 17 and some days thereafter, a positive phase storm appeared. In addition, anomalous equatorial ionization anomaly (EIA) inhibitions and developments were observed on July 16 and 17. There were also prominent nighttime enhancements in foF2 during these days, and the diurnal variation of foF2 was less clear than before.

  17. Solar cycle effect on geomagnetic storms caused by interplanetary magnetic clouds

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    2006-12-01

    Full Text Available We investigated geomagnetic activity which was induced by interplanetary magnetic clouds during the past four solar cycles, 1965–1998. We have found that the intensity of such geomagnetic storms is more severe in solar maximum than in solar minimum. In addition, we affirm that the average solar wind speed of magnetic clouds is faster in solar maximum than in solar minimum. In this study, we find that solar activity level plays a major role on the intensity of geomagnetic storms. In particular, some new statistical results are found and listed as follows. (1 The intensity of a geomagnetic storm in a solar active period is stronger than in a solar quiet period. (2 The magnitude of negative Bzmin is larger in a solar active period than in a quiet period. (3 Solar wind speed in an active period is faster than in a quiet period. (4 VBsmax in an active period is much larger than in a quiet period. (5 Solar wind parameters, Bzmin, Vmax and VBsmax are correlated well with geomagnetic storm intensity, Dstmin during a solar active period. (6 Solar wind parameters, Bzmin, and VBsmax are not correlated well (very poorly for Vmax with geomagnetic storm intensity during a solar quiet period. (7 The speed of the solar wind plays a key role in the correlation of solar wind parameters vs. the intensity of a geomagnetic storm. (8 More severe storms with Dstmin≤−100 nT caused by MCs occurred in the solar active period than in the solar quiet period.

  18. Coronal Mass Ejections, Interplanetary Shocks In Relation With Forbush Decreases Associated With Intense Geomagnetic Storms

    Science.gov (United States)

    Verma, P. L.; Patel, Nand Kumar; Prajapati, Mateswari

    2014-05-01

    Coronal mass ejections (CMEs} are the most energetic solar events in which large amount of solar plasma materials are ejected from the sun into heliosphere, causing major disturbances in solar wind plasma, Interplanetary shocks, Forbush decrease(Fds) in cosmic ray intensity and geomagnetic storms. We have studied Forbush decreases associated with intense geomagnetic storms observed at Oulu super neutron monitor, during the period of May 1998-Dec 2006 with coronal mass ejections (CMEs), X-ray solar flares and interplanetary shocks. We have found that all the (100%) Forbush decreases associated with intense geomagnetic storms are associated with halo and partial halo coronal mass ejections (CMEs). The association rate between halo and partial halo coronal mass ejections are found 96.00%and 04.00% respectively. Most of the Forbush decreases associated with intense geomagnetic storms (96.29%) are associated with X-ray solar flares of different categories . The association rates for X-Class, M-Class, and C- Class X -ray solar flares are found 34.62%, 50.00% and 15.38% respectively .Further we have concluded that majority of the Forbush decrease associated with intense geomagnetic storms are related to interplanetary shocks (92.30 %) and the related shocks are forward shocks. We have found positive co-relation with co-relation co-efficient .7025 between magnitudes of Forbush decreases associated with intense geomagnetic storms and speed of associated coronal mass ejections. Positive co-relation with co-relation co-efficient 0.48 has also been found between magnitudes of intense geomagnetic storms and speed of associated coronal mass ejections.

  19. A global scale picture of ionospheric peak electron density changes during geomagnetic storms

    Science.gov (United States)

    Kumar, Vickal V.; Parkinson, Murray L.

    2017-04-01

    Changes in ionospheric plasma densities can affect society more than ever because of our increasing reliance on communication, surveillance, navigation, and timing technology. Models struggle to predict changes in ionospheric densities at nearly all temporal and spatial scales, especially during geomagnetic storms. Here we combine a 50 year (1965-2015) geomagnetic disturbance storm time (Dst) index with plasma density measurements from a worldwide network of 132 vertical incidence ionosondes to develop a picture of global scale changes in peak plasma density due to geomagnetic storms. Vertical incidence ionosondes provide measurements of the critical frequency of the ionospheric F2 layer (foF2), a direct measure of the peak electron density (NmF2) of the ionosphere. By dissecting the NmF2 perturbations with respect to the local time at storm onset, season, and storm intensity, it is found that (i) the storm-associated depletions (negative storm effects) and enhancements (positive storm effects) are driven by different but related physical mechanisms, and (ii) the depletion mechanism tends to dominate over the enhancement mechanism. The negative storm effects, which are detrimental to HF radio links, are found to start immediately after geomagnetic storm onset in the nightside high-latitude ionosphere. The depletions in the dayside high-latitude ionosphere are delayed by a few hours. The equatorward expansion of negative storm effects is found to be regulated by storm intensity (farthest equatorward and deepest during intense storms), season (largest in summer), and time of day (generally deeper on the nightside). In contrast, positive storm effects typically occur on the dayside midlatitude and low-latitude ionospheric regions when the storms are in the main phase, regardless of the season. Closer to the magnetic equator, moderate density enhancements last up to 40 h during the recovery phase of equinox storms, regardless of the local time. Strikingly, high

  20. A study on precursors leading to geomagnetic storms using artificial neural network

    Science.gov (United States)

    Singh, Gaurav; Singh, A. K.

    2016-07-01

    Space weather prediction involves advance forecasting of the magnitude and onset time of major geomagnetic storms on Earth. In this paper, we discuss the development of an artificial neural network-based model to study the precursor leading to intense and moderate geomagnetic storms, following halo coronal mass ejection (CME) and related interplanetary (IP) events. IP inputs were considered within a 5-day time window after the commencement of storm. The artificial neural network (ANN) model training, testing and validation datasets were constructed based on 110 halo CMEs (both full and partial halo and their properties) observed during the ascending phase of the 24th solar cycle between 2009 and 2014. The geomagnetic storm occurrence rate from halo CMEs is estimated at a probability of 79%, by this model.

  1. Behavior of Plasma and Field Parameters and their Relationship with Geomagnetic Indices during Intense Geomagnetic Storms of Solar Cycle 23

    CERN Document Server

    Joshi, Navin Chandra; Pande, Seema; Pande, Bimal; Pandey, Kavita

    2010-01-01

    A correlative study between the geomagnetic indices and the peak values of various plasma and field parameters during rising, maximum and decay phases as well as during complete solar cycle 23 have been presented. We have also presented the lag/lead analysis between the maximum of Dst and peak values of plasma and field parameters and found that peak values of lag/lead time lies in the +/-10 hr interval. Three geomagnetic storms (GMSs) and associated solar sources observed during these phases of this solar cycle have also been studied and found that GMSs are associated with large flares and halo CMEs.

  2. Geomagnetic Storms and their Influence on the Human Brain Functional State

    Directory of Open Access Journals (Sweden)

    Elchin S. Babayev

    2005-01-01

    Full Text Available An investigation of the influence of geomagnetic storms of various intensities on healthy adults' human brain activity and its functional state was conducted. Results of electroencephalogram (EEG investigations were used as the most objective method reflecting functional state of the human brain. Studies on the influence of geomagnetic storms on the human brain functional state of healthy adult women patients (permanent group in states of relaxation, photo-stimulation and hyper-ventilation have revealed a negative influence of severe geomagnetic storms on functional state of the human brain. As a rule, during periods of strong geomagnetic disturbances, indisposition, weakness and presence of indistinct localized headaches were recorded for majority of patients. Complex of nonspecific shifts on EEG reflects disorganization of functional activity of cortex of large hemispheres of the human brain at geomagnetically disturbed days, which is likely connected with dysfunction of integrative subcortical systems, with disbalance of its ascending synchronizing and desynchronizing influences. Imbalance of activating and deactivating mechanisms including dysfunctions of ergo- and tropho-tropic over-segmentary centers was registered. Strengthening cortical connections in the right cortical hemisphere and their short circuit on temporal sections during geomagnetically disturbed days were observed, while, in geomagnetically quiet days, a profile of correlation interrelations reflected weak internal- and inter-hemispheric connections. The threshold of convulsive (spasmodic readiness of the human brain is reduced, which is especially dangerous for risk group persons. It is established that, in general, weak and moderate geomagnetic storms exert stimulating influence while strong disturbances of geomagnetic conditions activate braking (inhibiting processes.

  3. Ionosphere data assimilation modeling of 2015 St. Patrick's Day geomagnetic storm

    Science.gov (United States)

    Chen, C. H.; Lin, C. H.; Matsuo, T.; Chen, W. H.

    2016-11-01

    The ionospheric plasma disturbances during a severe storm can affect human activities and systems, such as navigation and HF communication systems. Therefore, the forecast of ionospheric electron density is becoming an important topic recently. This study is conducted with the ionospheric assimilation model by assimilating the total electron content observations into the thermosphere-ionosphere coupling model with different high-latitude ionospheric convection models, Heelis and Weimer, and further to forecast the variations of ionospheric electron density during the 2015 St. Patrick's Day geomagnetic storm. The forecast capabilities of these two assimilation models are evaluated by the root-mean-square error values in different regions to discuss its latitudinal effects. Results show the better forecast in the electron density at the low-latitude region during the storm main phase and the recovery phase. The well reproduced eastward electric field at the low-latitude region by the assimilation model reveals that the electric fields may be an important factor to have the contributions on the accuracy of ionospheric forecast.

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

    Science.gov (United States)

    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.

  5. The ionospheric response in the Brazilian sector during the super geomagnetic storm on 20 November 2003

    Directory of Open Access Journals (Sweden)

    F. Becker-Guedes

    2007-05-01

    Full Text Available A very intense geomagnetic storm (superstorm began with storm sudden commencement (SSC at 08:03 UT on 20 November 2003, as a result of the coronal mass ejection (CME by sunspot 484 hurled into space on 18 November 2003. The geomagnetic storm attained |Dst|max=472 nT at 20:00 UT (20 November. In this paper we present the simultaneous ionospheric sounding observations, using the Canadian Advanced Digital Ionosondes (CADIs, carried out from Palmas (PAL; 10.2° S, 48.2° W; dip latitude 5.5° S; a near equatorial station and São José dos Campos (SJC; 23.2° S, 45.9° W; dip latitude 17.6° S; station located under the crest of equatorial ionospheric anomaly, Brazil. In addition, total electron content (TEC measurements from several GPS receiving stations in the Brazilian sector during this storm are presented. The simultaneous ionospheric sounding observations carried out at SJC and PAL, and TEC observations on 3 consecutive days viz., 19 November (quiet, 20 November (disturbed and 21 November (recovery phase are presented. Salient features from the ionospheric observations in the Brazilian sector during the superstorm are discussed. The difference in the observed ionospheric response at the two stations (PAL and SJC is considerable. This is not surprising given that PAL is close to the magnetic equator and SJC is near the crest of the equatorial ionospheric anomaly (EIA. It should be pointed out that soon after the SSC (about 4 h later, the F-region critical frequency (foF2, the F-region peak height (hpF2, and variations of virtual heights at different frequencies (iso-frequency plots all show wavelike oscillations of the F-region during daytime at both the ionospheric sounding stations. Unusual rapid uplifting of F-region at PAL was observed during both the main and recovery phases of the storm.

  6. Radial distribution of the inner magnetosphere plasma pressure using low-altitude satellite data during geomagnetic storm: the March 1-8, 1982 Event

    CERN Document Server

    Stepanova, M; Bosqued, J M

    2007-01-01

    Plasma pressure distribution in the inner magnetosphere is one of the key parameters for understanding the main magnetospheric processes including geomagnetic storms and substorms. However, the pressure profiles obtained from in-situ particle measurements by the high-altitude satellites do not allow tracking the pressure variations related to the storms and substorms, because a time interval needed to do this generally exceeds the characteristic times of them. On contrary, fast movement of low-altitude satellites makes it possible to retrieve quasi-instantaneous profiles of plasma pressure along the satellite trajectory, using the fluxes of precipitating particles. For this study, we used the Aureol-3 satellite data for plasma pressure estimation, and the IGRF, Tsyganenko 2001 and Tsyganenko 2004 storm time geomagnetic field models for the pressure mapping into the equatorial plane. It was found that during quiet geomagnetic condition the radial pressure profiles obtained coincide with the profiles, obtained ...

  7. Identification of possible intense historical geomagnetic storms using combined sunspot and auroral observations from East Asia

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    2005-03-01

    Full Text Available Comprehensive catalogues of ancient sunspot and auroral observations from East Asia are used to identify possible intense historical geomagnetic storms in the interval 210 BC-AD 1918. There are about 270 entries in the sunspot catalogue and about 1150 entries in the auroral catalogue. Special databases have been constructed in which the scientific information in these two catalogues is placed in specified fields. For the purposes of this study, an historical geomagnetic storm is defined in terms of an auroral observation that is apparently associated with a particular sunspot observation, in the sense that the auroral observation occurred within several days of the sunspot observation. More precisely, a selection criterion is formulated for the automatic identification of such geomagnetic storms, using the oriental records stored in the sunspot and auroral databases. The selection criterion is based on specific assumptions about the duration of sunspot visibility with the unaided eye, the likely range of heliographic longitudes of an energetic solar feature, and the likely range of transit times for ejected solar plasma to travel from the Sun to the Earth. This selection criterion results in the identification of nineteen putative historical geomagnetic storms, although two of these storms are spurious in the sense that there are two examples of a single sunspot observation being associated with two different auroral observations separated by more than half a (synodic solar rotation period. The literary and scientific reliabilities of the East Asian sunspot and auroral records that define the nineteen historical geomagnetic storms are discussed in detail in a set of appendices. A possible time sequence of events is presented for each geomagnetic storm, including possible dates for both the central meridian passage of the sunspot and the occurrence of the energetic solar feature, as well as likely transit times for the ejected solar plasma

  8. Longitude dependent response of the GPS derived ionospheric ROTI to geomagnetic storms

    Science.gov (United States)

    Tanna, H. J.; Pathak, K. N.

    2014-08-01

    The local time dependent effects of geomagnetic storm on the ionospheric TEC and Rate of change of TEC Index (ROTI) are studied here using the GPS data for four different low latitude stations: Ogaswara, Japan (24.29 °N, 153.91 °E; Geomagnetic: 17.21 °N, 136.16 °W); Surat, India (21.16 °N, 72.78 °E; Geomagnetic: 12.88 °N, 146.91 °E); Bogota, Colombia (4.64 °N, -74.09 °E; Geomagnetic: 14.42 °N, 1.67 °W); and Kokee park Waimea, Hawaii, US (22.12 °N, -159.67 °E; Geomagnetic: 22.13 °N, 91.19 °W). The solar wind velocity and geomagnetic indices: Dst, Kp and IMF Bz are utilized to validate the geomagnetic storms registered during the years 2011 and 2012. Using the GPS based TEC data and computed values of ROTI, the storm induced ionospheric irregularities generation and inhibition has been studied for all stations. The present study suggests that, the F-region irregularities of a scale length of few kilometers over the magnetic equator are locally affected by geomagnetic storms. This study also shows a good agreement (70-84 %) with the Aaron's criteria (Aarons, Radio Sci., 26:1131-1149, 1991; Biktash, Ann. Geophys., 19:731-739, 2004) as significant absence and enhancement of ROTI was found to be influenced by the local time of the negative peak of Dst index association.

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

    Science.gov (United States)

    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.

  10. Study of cosmic ray intensity and geomagnetic storms with solar wind parameters during the period 1998-2005

    Science.gov (United States)

    Kharayat, Hema; Prasad, Lalan

    2017-01-01

    The aim of this paper is to study the effect of solar wind parameters (solar wind speed V, plasma flow pressure, and plasma density) on cosmic ray intensity and on geomagnetic storms for the period 1998-2005 (solar cycle 23). A Chree analysis by the superposed epoch method has been done for the study. From the present study we have found that the solar wind speed is a highly effective parameter in producing cosmic ray intensity decreases and geomagnetic storms. No time lag is found between cosmic ray intensity decreases, geomagnetic storms, and peak value of solar wind speed. Further, we have found that the plasma flow pressure is effectively correlated with geomagnetic storms but it is weakly correlated with cosmic ray intensity. The cosmic ray intensity and geomagnetic storms are found to be weakly correlated with plasma density. The decrease in cosmic ray intensity and geomagnetic storms takes place one day after the peak values of plasma flow pressure and plasma density. There is a time lag of one day between solar wind parameters (plasma flow pressure and plasma density) and cosmic ray intensity decrease, geomagnetic storms. Also, we have found a high correlation of cosmic ray intensity and geomagnetic storms with the product of interplanetary magnetic field B and solar wind speed V i.e. B\\cdot V. This study may be useful in predicting the space-weather phenomena.

  11. Study of the Forbush Decreases, Geomagnetic Storms, and Ground-Level Enhancements in Selected Intervals and Their Space Weather Implications

    Science.gov (United States)

    Badruddin; Kumar, Anand

    2015-04-01

    We analysed geomagnetic storms, ground-level enhancements (GLEs), and Forbush decreases in cosmic-ray intensity that occurred in selected intervals. We used data of ground-based neutron monitors for the cosmic-ray intensity. We used the geomagnetic index Dst as a measure of the geomagnetic storm intensity. Solar observations and interplanetary plasma/field parameters were used to identify the solar cause(s), interplanetary structure(s), and physical mechanism(s) responsible for the geomagnetic storms, the Forbush decreases, and the GLEs of different amplitudes and time profiles; all of them occurring within four selected periods of one month each. The observed differences in cosmic-ray and geomagnetic-activity responses to the same solar sources were used to distinguish the structures and mechanisms responsible for transient cosmic-ray modulation and geomagnetic storms.

  12. Plasmaspheric dynamics resulting from the hallowe'en 2003 geomagnetic storms

    OpenAIRE

    Kale, Z.C.; Mann, I. R.; C. L. Waters; Vellante, M.; T. L. Zhang; Honary, Farideh

    2009-01-01

    Cross-phase-derived plasma mass density trends during the Hallowe'en 2003 geomagnetic storms are presented for 38° magnetic latitude 63° (1.61 ≤ L ≤ 5.10), using data from the SAMNET (Subauroral Magnetometer Network), BGS (British Geological Survey), and SEGMA (South European Geomagnetic Array), ground-based magnetometer arrays in Europe. At all latitudes monitored, a rapid increase of total mass density is observed immediately following the initial storm sudden commencement at 0611 UT on 29 ...

  13. PAMELA's measurements of geomagnetic cutoff variations during solar energetic particle events

    CERN Document Server

    Bruno, A; Barbarino, G C; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bravar, U; Cafagna, F; Campana, D; Carbone, R; Carlson, P; Casolino, M; Castellini, G; Christian, E C; De Donato, C; de Nolfo, G A; De Santis, C; De Simone, N; Di Felice, V; Formato, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Lee, M; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mergè, M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Ryan, J M; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stochaj, S; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G I; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N; Zverev, V G

    2015-01-01

    Data from the PAMELA satellite experiment were used to measure the geomagnetic cutoff for high-energy ($\\gtrsim$ 80 MeV) protons during the solar particle events on 2006 December 13 and 14. The variations of the cutoff latitude as a function of rigidity were studied on relatively short timescales, corresponding to single spacecraft orbits (about 94 minutes). Estimated cutoff values were cross-checked with those obtained by means of a trajectory tracing approach based on dynamical empirical modeling of the Earth's magnetosphere. We find significant variations in the cutoff latitude, with a maximum suppression of about 6 deg for $\\sim$80 MeV protons during the main phase of the storm. The observed reduction in the geomagnetic shielding and its temporal evolution were compared with the changes in the magnetosphere configuration, investigating the role of IMF, solar wind and geomagnetic (Kp, Dst and Sym-H indexes) variables and their correlation with PAMELA cutoff results.

  14. An investigation into the correlation of geomagnetic storms with tropospheric parameters over the South Pole

    Directory of Open Access Journals (Sweden)

    M. M. Lam

    Full Text Available We test the proposal that the Sun’s magnetic activity, communicated via the solar wind, provides a link between solar variability and the Earth’s climate in the Antarctic troposphere. The strength of a geomagnetic storm is one indicator of the state of the solar wind; therefore, we use the dates of 51 moderate to strong winter geomagnetic storms from the period 1961–1990 to conduct a series of superposed epoch analyses of the winter South Pole isobaric height and temperature, at pressures of between 100–500 mbar. Using Student’s t -test to compare the mean value of the pre- and post-storm data sets, we find no evidence to support the hypothesis that there is a statistically-significant correlation between the onset of a geomagnetic storm and changes in the isobaric temperature or height of the troposphere and lower stratosphere over the South Pole during winter months. This concurs with a similar study of the variability of the troposphere and lower stratosphere over the South Pole (Lam and Rodger, 2002 which uses drops in the level of observed galactic cosmic ray intensity, known as Forbush decreases, as a proxy for solar magnetic activity instead of geomagnetic storms.

    Key words. Interplanetary physics (solar wind plasma; cosmic rays – Atmospheric composition and structure (pressure, density and temperature

  15. Hemispheric differences in the response of the upper atmosphere to the August 2011 geomagnetic storm: A simulation study

    Science.gov (United States)

    Yiğit, Erdal; Frey, Harald U.; Moldwin, Mark B.; Immel, Thomas J.; Ridley, Aaron J.

    2016-04-01

    Using a three-dimensional nonhydrostatic general circulation model, we investigate the response of the thermosphere-ionosphere system to the 5-6 August 2011 major geomagnetic storm. The model is driven by measured storm-time input data of the Interplanetary Magnetic Field (IMF), solar activity, and auroral activity. Simulations for quiet steady conditions over the same period are performed as well in order to assess the response of the neutral and plasma parameters to the storm. During the storm, the high-latitude mean ion flows are enhanced by up to 150-180%. Largest ion flows are found in the main phase of the storm. Overall, the global mean neutral temperature increases by up to 15%, while the maximum thermal response is higher in the winter Southern Hemisphere at high-latitudes than the summer Northern Hemisphere: 40% vs. 20% increase in high-latitude mean temperature, respectively. The global mean Joule heating increases by more than a factor of three. There are distinct hemispheric differences in the magnitude and morphology of the horizontal ion flows and thermospheric flows during the different phases of the storm. The largest hemispheric difference in the thermospheric circulation is found during the main and recovery phases of the storm, demonstrating appreciable geographical variations. The advective forcing is found to contribute to the modeled hemispheric differences.

  16. Global and Meso-scale Thermospheric Neutral Wind Response to Geomagnetic Storm

    Science.gov (United States)

    Lu, G.; Conde, M.; Doornbos, E.

    2015-12-01

    This paper presents a case study of thermospheric response to the 5 April 2010 geomagnetic storm. The NCAR Thermosphere-Ionosphere-Mesosphere Electrodynamic General Circulation Model (TIMEGCM) is used to investigate thermospheric neutral wind variations during the storm, and the model results are validated through comparison with ground and space based observations. More specifically, we conduct detailed inter-comparison of the winds observed by scanning Doppler imagers (SDI) in Alaska with those derived from the TIMEGCM simulations in order to assess model's ability in reproducing the observed meso-scale wind field. The thermospheric winds obtained from the accelerometers on board the GOCE satellite are also used to validate the simulation results on a global scale. While globally the wind velocity tends to be smaller than ion drift velocity, locally the winds can exceed ion drifts and also blow in the different direction than the ions. We will discuss how the thermospheric winds affect the energetic coupling of the magnetosphere-ionosphere-thermosphere system in terms of Joule heating and field-aligned currents.

  17. Characterizing magnetopause shadowing effects in the outer electron radiation belt during geomagnetic storms

    Science.gov (United States)

    Herrera, D.; Maget, V. F.; Sicard-Piet, A.

    2016-10-01

    Relativistic electrons dynamics is still challenging to predict during the main phase of a storm. In particular, three dimensions radiation belt models, for which temporal resolution is limited, fail in predicting their behavior, especially when dropouts occur. In this paper we present a new model of magnetopause shadowing losses to be incorporated into the ONERA Salammbô code in order to improve the model accuracy. We show in this paper that above a few hundred keVs, magnetopause shadowing is the first contribution to losses in the outer electron belt during dropout events. Global variations of Earth-magnetopause distance and relativistic electron flux have been analyzed to establish the correlation between the magnetopause shadowing and dropouts on the outer electron radiation belt during geomagnetic storms. To that purpose, a Superposed Epoch Analysis has been done using NOAA Polar-orbiting Operational Environmental Satellite 15 measurements. First, a list of 67 Stream Interfaces has been used to validate the method, and then the Superposed Epoch Analysis has been run over more than one solar cycle. Our results show that the model of magnetopause location we have developed fits well with a Superposed Epoch Analysis performed and that we are able to define a criteria based on it that detect intense dropouts. Finally, we have included this model in the Salammbô code, and we present here the improvements obtained as well as the validation made.

  18. MORPHOLOGY CATEGORY OF GEOMAGNETIC STORMS AND CHARACTERISTICS OF INTERPLANETARY MAGNETIC CLOUDS

    Institute of Scientific and Technical Information of China (English)

    章公亮

    1991-01-01

    Six typical geomagnetic storms are analyzed from the aspect of varieties of morphologycategories of magnetic storms with sudden commencement caused by interplanetary magneticclouds. The main conclusions obtained are drawn. The high-density structure in front ofmagnetic cloud is an important factor in determining the property of the initial phase ofgeomagnetic storm. Under similar conditions for the magnetic field of magnetic cloud, thevelocities of both the background solar wind and the magnetic cloud affect the developmentand intensity of magnetic storm. The onset and recovery of strong main phase are control-led by the orientation of the field vector inclination with respect to the ecliptic plane. Oneof the main features of the storm generated from a positive magnetic cloud is the long-delayed main phase. The solar wind streams behind the magnetic cloud keep affecting therecovery of main phase of magnetic storm.

  19. Detailed Analysis of Solar Data Related to Historical Extreme Geomagnetic Storms: 1868 – 2010

    DEFF Research Database (Denmark)

    Lefèvre, Laure; Vennerstrøm, Susanne; Dumbović, Mateja

    2016-01-01

    An analysis of historical Sun–Earth connection events in the context of the most extreme space weather events of the last ∼ 150 years is presented. To identify the key factors leading to these extreme events, a sample of the most important geomagnetic storms was selected based mainly on the well-...

  20. GPS phase scintillation at high latitudes during the geomagnetic storm of 17-18 March 2015

    DEFF Research Database (Denmark)

    Prikryl, P.; Ghoddousi-Fard, R.; Weygand, J. M.

    2016-01-01

    The geomagnetic storm of 17–18 March 2015 was caused by the impacts of a coronal mass ejection and a high-speed plasma stream from a coronal hole. The high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including GPS receivers, HF radars, ionosondes, riometers...

  1. Modeling the recovery phase of extreme geomagnetic storms

    CERN Document Server

    Cid, C; Saiz, E; Cerrato, Y; Aguado, J; Guerrero, A

    2014-01-01

    The recovery phase of the largest storms ever recorded has been studied. These events provide an extraordinary opportunity for two goals: (1) to validate the hyperbolic model by Aguado et al. [2010] for the recovery phase after disturbances as severe as the Carrington event, or that related to the Hydro-Quebec blackout in March 1989, and (2) to check whether the linear relationship between the recovery time and the intensity of the storm still complies. Our results reveal the high accuracy of the hyperbolic decay function to reproduce the recovery phase of the magnetosphere after an extreme storm. Moreover, the characteristic time that takes the magnetosphere to recover depends in an exponential way on the intensity of the storm, as indicated by the relationship between the two parameters involved in the hyperbolic decay. This exponential function can be approached by a linear function when the severity of the storm diminishes.

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

    Science.gov (United States)

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

    2015-08-01

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

  3. Interplanetary drivers of daytime penetration electric field into equatorial ionosphere during CIR-induced geomagnetic storms

    Science.gov (United States)

    Yeeram, Thana

    2017-05-01

    Observations based on the magnetometer data of the response of the daytime equatorial electric field to the geomagnetic storms induced by corotating interaction regions (CIRs) during 2007-2010 reveal many events of striking long duration of multiple short-lived prompt penetration electric fields (PPEFs). The PPEFs essentially occurred in the main phase of the storms, which are associated with the ring current and magnetic reconnection of the southward z-component of the interplanetary magnetic field (IMF Bz) in relation to the Alfvén waves. The behaviors of the electric field penetration during the storms are consistent with the shielding theory. Particularly, the PPEF is found to be complex due to transient variations in the solar wind dynamic pressure (SWDP) and the IMF Bz in the CIRs. The PPEF is temporary suppressed for about an hour under a shock in association with a drop in the SWDP. The interplanetary electric field Ey is the main driver of the PPEFs, when the solar wind speed, SWDP, and the symmetric ring current are nearly constant, even in the recovery phase. The PPEF is allowed under the condition of high and variable SWDP. The shocks with a northward IMF Bz shield the PPEFs when the SWDP is nearly constant. The partial ring current is strongest in the large and northward IMF Bz, where the shielding effect is greater than the undershielding caused by the large SWDP. The results may provide an important step to study equatorial and low latitude ionospheric electrodynamics in the solar minimum conditions.

  4. COMPARATIVE EVALUATION OF THE INFLUENCING EFFECTS OF GEOMAGNETIC SOLAR STORMS ON EARTHQUAKES IN ANATOLIAN PENINSULA

    Directory of Open Access Journals (Sweden)

    Yesugey Sadik Cengiz

    2009-07-01

    Full Text Available Earthquakes are tectonic events that take place within the fractures of the earth's crust, namely faults. Above certain scale, earthquakes can result in widespread fatalities and substantial financial loss. In addition to the movement of tectonic plates relative to each other, it is widely discussed that there are other external influences originate outside earth that can trigger earthquakes. These influences are called "triggering effects". The purpose of this article is to present a statistical view to elaborate if the solar geomagnetic storms trigger earthquakes.As a model, the research focuses on the Anatolian peninsula, presenting 41 years of historical data on magnetic storms and earthquakes collated from national and international resources. As a result of the comparative assessment of the data, it is concluded that the geomagnetic storms do not trigger earthquakes.

  5. Investigation of Ionospheric Response to Geomagnetic Storms over a Low Latitude Station, Ile-Ife, Nigeria

    Science.gov (United States)

    Jimoh, Oluwaseyi E.; Yesufu, Thomas K.; Ariyibi, Emmanuel A.

    2016-06-01

    Due to several complexities associated with the equatorial ionosphere, and the significant role which the total electron content (TEC) variability plays in GPS signal transmission, there is the need to monitor irregularities in TEC during storm events. The GPS SCINDA receiver data at Ile-Ife, Nigeria, was analysed with a view to characterizing the ionospheric response to geomagnetic storms on 9 March and 1 October 2012. Presently, positive storm effects, peaks in TEC which were associated with prompt penetration of electric fields and changes in neutral gas composition were observed for the storms. The maximum percentage deviation in TEC of about 120 and 45% were observed for 9 March and 1 October 2012, respectively. An obvious negative percentage TEC deviation subsequent to sudden storm commencement (SSC) was observed and besides a geomagnetic storm does not necessarily suggest a high scintillation intensity (S4) index. The present results show that magnetic storm events at low latitude regions may have an adverse effect on navigation and communication systems.

  6. A comparison of the ground magnetic responses during the 2013 and 2015 St. Patrick's Day geomagnetic storms

    DEFF Research Database (Denmark)

    Xu, Z.; Hartinger, M. D.; Clauer, Robert C.

    2017-01-01

    2015 geomagnetic storms driven by coronal mass ejections (CME) provide one such opportunity. The two events occur during the same solar illumination conditions; in particular, both occur near equinox on the same day of the year leading to similar ionospheric conductivity profiles. Moreover, both CMEs...... the 2015 storm; these asymmetries are not present in the 2013 storm....

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

    Science.gov (United States)

    Doumbia, Vafi; Boka, Kouadio; Kouassi, Nguessan; Didier Franck Grodji, Oswald; Amory-Mazaudier, Christine; Menvielle, Michel

    2017-01-01

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

  8. A study of solar and interplanetary parameters of CMEs causing major geomagnetic storms during SC 23

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    C. Oprea

    2013-08-01

    Full Text Available In this paper we analyse 25 Earth-directed and strongly geoeffective interplanetary coronal mass ejections (ICMEs which occurred during solar cycle 23, using data provided by instruments on SOHO (Solar and Heliospheric Observatory, ACE (Advanced Composition Explorer and geomagnetic stations. We also examine the in situ parameters, the energy transfer into magnetosphere, and the geomagnetic indexes. We compare observed travel times with those calculated by observed speeds projected into the plane of the sky and de-projected by a simple model. The best fit was found with the projected speeds. No correlation was found between the importance of a flare and the geomagnetic Dst (disturbance storm time index. By comparing the in situ parameters with the Dst index we find a strong connection between some of these parameters (such as Bz, Bs · V and the energy transfer into the magnetosphere with the strength of the geomagnetic storm. No correlation was found with proton density and plasma temperature. A superposed epoch analysis revealed a strong dependence of the Dst index on the southward component of interplanetary magnetic field, Bz, and to the Akasofu coupling function, which evaluates the energy transfer between the ICME and the magnetosphere. The analysis also showed that the geomagnetic field at higher latitudes is disturbed before the field around the Earth's equator.

  9. Relationship between the Magnetic Flux of Solar Eruptions and the Ap Index of Geomagnetic Storms

    CERN Document Server

    Chertok, I M; Abunin, A A; Belov, A V; Grechnev, V V

    2014-01-01

    Solar coronal mass ejections (CMEs) are main drivers of the most powerful non-recurrent geomagnetic storms. In the extreme-ultraviolet range, CMEs are accompanied by bright post-eruption arcades and dark dimmings. The analysis of events of the Solar Cycle 23 (Chertok et al., 2013, Solar Phys. 282, 175) revealed that the summarized unsigned magnetic flux in the arcades and dimming regions at the photospheric level, Phi, is significantly related to the intensity (Dst index) of geomagnetic storms. This provides the basis for the earliest diagnosis of geoefficiency of solar eruptions. In the present article, using the same data set, we find that a noticeable correlation exists also between the eruptive magnetic flux, Phi, and another geomagnetic index, Ap. As the magnetic flux increases from tens to approx. 500 (in units of 10^{20} Mx), the geomagnetic storm intensity measured by the 3-hour Ap index, enhances in average from Ap approx. 50 to a formally maximum value of 400 (in units of 2 nT). The established rela...

  10. Concerning long-term geomagnetic variations and space climatology

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    K.-H. Glassmeier

    2004-11-01

    Full Text Available During geomagnetic polarity transitions the surface magnetic field of the Earth decays to about 25% and less of its present value. This implies a shrinking of the terrestrial magnetosphere and posses the question of whether magnetospheric magnetic field variations scale in the same manner. Furthermore, the geomagnetic main field also controls the magnetospheric magnetic field and space weather conditions. Long-term geomagnetic variations are thus intimately related to space climate. We critically assess existing scaling relations and derive new ones for various magnetospheric parameters. For example, we find that ring current perturbations do not increase with decreasing dipole moment. And we derive a scaling relation for the polar electrojet contribution, indicating a weak increase with increasing internal field. From this we infer that the ratio between external and internal field contributions may be weakly enhanced during polarity transitions. Our scaling relations also provide more insight on the importance of the internal geomagnetic field contribution for space climate.

  11. Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms

    Science.gov (United States)

    Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery

    Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean

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

    Science.gov (United States)

    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.

  13. The driving mechanisms of particle precipitation during the moderate geomagnetic storm of 7 January 2005

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    N. Longden

    2007-10-01

    Full Text Available The arrival of an interplanetary coronal mass ejection (ICME triggered a sudden storm commencement (SSC at ~09:22 UT on the 7 January 2005. The ICME followed a quiet period in the solar wind and interplanetary magnetic field (IMF. We present global scale observations of energetic electron precipitation during the moderate geomagnetic storm driven by the ICME. Energetic electron precipitation is inferred from increases in cosmic noise absorption (CNA recorded by stations in the Global Riometer Array (GLORIA. No evidence of CNA was observed during the first four hours of passage of the ICME or following the sudden commencement (SC of the storm. This is consistent with the findings of Osepian and Kirkwood (2004 that SCs will only trigger precipitation during periods of geomagnetic activity or when the magnetic perturbation in the magnetosphere is substantial. CNA was only observed following enhanced coupling between the IMF and the magnetosphere, resulting from southward oriented IMF. Precipitation was observed due to substorm activity, as a result of the initial injection and particles drifting from the injection region. During the recovery phase of the storm, when substorm activity diminished, precipitation due to density driven increases in the solar wind dynamic pressure (Pdyn were identified. A number of increases in Pdyn were shown to drive sudden impulses (SIs in the geomagnetic field. While many of these SIs appear coincident with CNA, SIs without CNA were also observed. During this period, the threshold of geomagnetic activity required for SC driven precipitation was exceeded. This implies that solar wind density driven SIs occurring during storm recovery can drive a different response in particle precipitation to typical SCs.

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

    Science.gov (United States)

    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.

  15. Probing geomagnetic storm-driven magnetosphere-ionosphere dynamics in D-region via propagation characteristics of very low frequency radio signals

    Science.gov (United States)

    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

  16. Geomagnetic storms during the last decade: Cluster and Double Star observations (Invited)

    Science.gov (United States)

    Escoubet, C.; Taylor, M. G.; Masson, A.; Laakso, H. E.; Liu, Z.; Goldstein, M. L.

    2013-12-01

    The launch of the Cluster spacecraft almost coincided with one of the largest geomagnetic storm of the last decade, well known as the "Bastille Day" storm, on 14-15 July 2000. Planned on 15 July, the launch was aborted a few minutes before due to a thunderstorm that had hit the Baikonour cosmodrome and made a disruption in the communication lines with the rocket. The launch took place the day after, on 16 July 2000. Our US colleagues had warned us about the storm and recommended not to launch on 15 July. Given the facts that (1) Cluster was built to study the effects of space weather and geomagnetic storms and (2) that the Russian launch authorities were not concerned for the Soyuz rocket, it was decided to go ahead with the launch. The launch was fine and, after a second launch less than a month later, the four Cluster spacecraft were put successfully in their 4x19 RE polar orbit. Since then, Cluster has observed many geomagnetic storms and could observe, for the first time with a constellation of four spacecraft, the dynamics induced in the magnetosphere by coronal mass ejections or interplanetary shocks coming from the Sun. In this talk we will use storms observed by Cluster and Double Star in the last decade to illustrate how the magnetosphere was affected. We have observed large compressions of the magnetosphere, distortions of the polar cusp, acceleration of particles associated with chorus and ULF waves, intensification of the ring current imaged by energetic neutral atom imagers, oxygen outflow from polar regions, and tail current sheet motions.

  17. The presence of large sunspots near the central solar meridian at the times of major geomagnetic storms

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    D. M. Willis

    2009-01-01

    Full Text Available A further study is made of the validity of a technique developed by the authors to identify historical occurrences of intense geomagnetic storms, which is based on finding approximately coincident observations of sunspots and aurorae recorded in East Asian histories. Previously, the validity of this technique was corroborated using scientific observations of aurorae in Japan during the interval 1957–2004 and contemporaneous white-light images of the Sun obtained by the Royal Greenwich Observatory, the Big Bear Solar Observatory, the Debrecen Heliophysical Observatory, and the Solar and Heliospheric Observatory spacecraft. The present investigation utilises a list of major geomagnetic storms in the interval 1868–2008, which is based on the magnitude of the AA* magnetic index, and reconstructed solar images based on the sunspot observations acquired by the Royal Greenwich Observatory during the shorter interval 1874–1976. It is found that a sunspot large enough to be seen with the unaided eye by an "experienced" observer was located reasonably close to the central solar meridian for almost 90% of these major geomagnetic storms. Even an "average" observer would easily achieve a corresponding success rate of 70% and this success rate increases to about 80% if a minority of ambiguous situations are interpreted favourably. The use of information on major geomagnetic storms, rather than modern auroral observations from Japan, provides a less direct corroboration of the technique for identifying historical occurrences of intense geomagnetic storms, if only because major geomagnetic storms do not necessarily produce auroral displays over East Asia. Nevertheless, the present study provides further corroboration of the validity of the original technique for identifying intense geomagnetic storms. This additional corroboration of the original technique is important because early unaided-eye observations of sunspots and aurorae provide the only

  18. A new parameter of geomagnetic storms for the severity of space weather

    Science.gov (United States)

    Balan, N.; Batista, I. S.; Tulasi Ram, S.; Rajesh, P. K.

    2016-12-01

    Using the continuous Dst data available since 1957 and H component data for the Carrington space weather event of 1859, the paper shows that the mean value of Dst during the main phase of geomagnetic storms, called mean DstMP, is a unique parameter that can indicate the severity of space weather. All storms having high mean DstMP (≤-250 nT), which corresponds to high amount of energy input in the magnetosphere-ionosphere system in short duration, are found associated with severe space weather events that caused all known electric power outages and telegraph system failures.

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

    Science.gov (United States)

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

    2014-01-01

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

  20. Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

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    A. A. Namgaladze

    Full Text Available Current theories of F-layer storms are discussed using numerical simulations with the Upper Atmosphere Model, a global self-consistent, time dependent numerical model of the thermosphere-ionosphere-plasmasphere-magnetosphere system including electrodynamical coupling effects. A case study of a moderate geomagnetic storm at low solar activity during the northern winter solstice exemplifies the complex storm phenomena. The study focuses on positive ionospheric storm effects in relation to thermospheric disturbances in general and thermospheric composition changes in particular. It investigates the dynamical effects of both neutral meridional winds and electric fields caused by the disturbance dynamo effect. The penetration of short-time electric fields of magnetospheric origin during storm intensification phases is shown for the first time in this model study. Comparisons of the calculated thermospheric composition changes with satellite observations of AE-C and ESRO-4 during storm time show a good agreement. The empirical MSISE90 model, however, is less consistent with the simulations. It does not show the equatorward propagation of the disturbances and predicts that they have a gentler latitudinal gradient. Both theoretical and experimental data reveal that although the ratio of [O]/[N2] at high latitudes decreases significantly during the magnetic storm compared with the quiet time level, at mid to low latitudes it does not increase (at fixed altitudes above the quiet reference level. Meanwhile, the ionospheric storm is positive there. We conclude that the positive phase of the ionospheric storm is mainly due to uplifting of ionospheric F2-region plasma at mid latitudes and its equatorward movement at low latitudes along geomagnetic field lines caused by large-scale neutral wind circulation and the passage of travelling atmospheric disturbances (TADs. The calculated zonal electric field disturbances also help

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

    Science.gov (United States)

    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

  2. Effect of a huge crustal conductivity anomaly on the H-component of geomagnetic variations recorded in central South America

    Science.gov (United States)

    Padilha, Antonio L.; Alves, Livia R.; Silva, Graziela B. D.; Espinosa, Karen V.

    2017-04-01

    We describe here an analysis of the H-component of the geomagnetic field recorded in several temporary stations operating simultaneously in the central-eastern region of Brazil during nighttime pulsation events in 1994 and the sudden commencement of the St. Patrick's Day magnetic storm in 2015. A significant amplification in the amplitude of the geomagnetic variations is consistently observed in one of these stations. Magnetovariational analysis indicates that the amplification factor is period dependent with maximum amplitude around 100 s. Integrated magnetotelluric (MT) and geomagnetic depth soundings (GDS) have shown that this station is positioned just over a huge 1200-km-long crustal conductor (estimated bulk conductivity greater than 1 S/m). We propose that the anomalous signature of the geomagnetic field at this station is due to the high reflection coefficient of the incident electromagnetic wave at the interface with the very good conductor and by skin effects damping the electromagnetic wave in the conducting layers overlying the conductor. There are some indication from the GDS data that the conductor extends southward beneath the sediments of the Pantanal Basin. In this region is being planned the installation of a new geomagnetic observatory, but its preliminary data suggest anomalous geomagnetic variations. We understand that a detailed MT survey must be carried out around the chosen observatory site to evaluate the possible influence of induced currents on the local geomagnetic field.[Figure not available: see fulltext.

  3. A novel approach to the dynamical complexity of the Earth's magnetosphere at geomagnetic storm time-scales based on recurrences

    Science.gov (United States)

    Donner, Reik; Balasis, Georgios; Stolbova, Veronika; Wiedermann, Marc; Georgiou, Marina; Kurths, Jürgen

    2016-04-01

    Magnetic storms are the most prominent global manifestations of out-of-equilibrium magnetospheric dynamics. Investigating the dynamical complexity exhibited by geomagnetic observables can provide valuable insights into relevant physical processes as well as temporal scales associated with this phenomenon. In this work, we introduce several innovative data analysis techniques enabling a quantitative analysis of the Dst index non-stationary behavior. Using recurrence quantification analysis (RQA) and recurrence network analysis (RNA), we obtain a variety of complexity measures serving as markers of quiet- and storm-time magnetospheric dynamics. We additionally apply these techniques to the main driver of Dst index variations, the V BSouth coupling function and interplanetary medium parameters Bz and Pdyn in order to discriminate internal processes from the magnetosphere's response directly induced by the external forcing by the solar wind. The derived recurrence-based measures allow us to improve the accuracy with which magnetospheric storms can be classified based on ground-based observations. The new methodology presented here could be of significant interest for the space weather research community working on time series analysis for magnetic storm forecasts.

  4. Analysis of the monitoring data of geomagnetic storm interference in the electrification system of a high-speed railway

    Science.gov (United States)

    Liu, Lianguang; Ge, Xiaoning; Zong, Wei; Zhou, You; Liu, Mingguang

    2016-10-01

    To study the impact of geomagnetic storm on the equipment of traction electrification system in the high-speed railway, geomagnetically induced current (GIC) monitoring devices were installed in the Hebi East traction power supply substation of the Beijing-Hong Kong Dedicated Passenger Line in January 2015, and GICs were captured during the two geomagnetic storms on 17 March and 23 June 2015. In order to investigate the GIC flow path, both in the track circuit and in the traction network adopting the autotransformer feeding system, a GIC monitor plan was proposed for the electrical system in the Hebi East traction power supply substation. This paper analyzes the correlation between the GIC captured on 17 March and the geomagnetic data obtained from the Malingshan Geomagnetic Observatory and presents a regression analysis between the measured GIC and the calculated geoelectric fields on 23 June in the high-speed railway. The maximum GICs measured in the track circuit are 1.08 A and 1.74 A during the two geomagnetic storms. We find that it is necessary to pay attention on the throttle transformers and track circuits, as the most sensitive elements responding to the extreme geomagnetic storms in the high-speed railway.

  5. Development of a CME-associated geomagnetic storm intensity prediction tool

    Science.gov (United States)

    Wu, C. C.; DeHart, J. M.

    2015-12-01

    From 1995 to 2012, the Wind spacecraft recorded 168 magnetic cloud (MC) events. Among those events, 79 were found to have upstream shock waves and their source locations on the Sun were identified. Using a recipe of interplanetary magnetic field (IMF) Bz initial turning direction after shock (Wu et al., 1996, GRL), it is found that the north-south polarity of 66 (83.5%) out of the 79 events were accurately predicted. These events were tested and further analyzed, reaffirming that the Bz intial turning direction was accurate. The results also indicate that 37 of the 79 MCs originate from the north (of the Sun) averaged a Dst_min of -119 nT, whereas 42 of the MCs originating from the south (of the Sun) averaged -89 nT. In an effort to provide this research to others, a website was built that incorporated various tools and pictures to predict the intensity of the geomagnetic storms. The tool is capable of predicting geomagnetic storms with different ranges of Dst_min (from no-storm to gigantic storms). This work was supported by Naval Research Lab HBCU/MI Internship program and Chief of Naval Research.

  6. Modeling of the Radiation Belt Dynamics During the Two Largest Geomagnetic Storms of Solar Cycle 24

    Science.gov (United States)

    Zheng, Y.; Rastaetter, L.; Kuznetsova, M. M.

    2016-12-01

    In this paper, radiation belt response to the two largest geomagnetic storms of Solar Cycle 24 (17 March 2015 and the 22 June 2015) is investigated in detail. Even though both storms are primarily CME driven, each has its own complexities [Liu et al., 2015, Kataoka et al., 2015]. Using the CCMC's run-on-request system, modeling results using the RBE (Radiation Belt Environment) model within the SWMF (Space Weather Modeling Framework) and the RBE model coupled with the SWMF and RCM (Rice Convection Model, which takes the ring current's contribution into consideration) will be examined. Comparative and comprehensive analyses of the same event from two different models and of two events from the same model/model suite will be provided. Focus will be specially given to impacts of different solar wind drivers on radiation belt dynamics and to the coupling and interactions of different plasma populations/physical processes within the region. Liu, Ying D., H. Hu, R. Wang, Z. Yang, B., Zhu, Y. A., Liu, J. G. Luhmann, J. D. Richardson (2015), Plasma and Magnetic Field Characteristics of Solar Coronal Mass Ejections in Relation to Geomagnetic Storm Intensity and Variability, The Astrophysical Journal Letters, Volume 809, Issue 2, article id. L34, 6 pp. doi:10.1088/2041-8205/809/2/L34. Kataoka, R., D. Shiota, E. Kilpua, and K. Keika (2015), Pileup accident hypothesis of magnetic storm on 17 March 2015, Geophys. Res. Lett., 42, 5155-5161, doi:10.1002/2015GL064816.

  7. Ion heating during geomagnetic storms measured using energetic neutral atom imaging

    Science.gov (United States)

    Keesee, Amy; Elfritz, Justin; Katus, Roxanne; Scime, Earl

    2015-11-01

    Energy from the solar wind is deposited into the magnetosphere during geomagnetic storms. Much of this energy is deposited into the plasma sheet, driving phenomena that leads to heating. The plasma sheet ions are then injected to the inner magnetosphere, driving the ring current. While ions can undergo adiabatic heating during typical drift motion, collisional and wave-particle interactions can also lead to ion heating. A technique to measure ion temperatures using energetic neutral atom (ENA) data has been developed using ENA data from the Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) mission global maps of ion temperature during the evolution of geomagnetic storms are made. These maps exhibit the location and characteristics of regions of ion heating and during which storm phase they occur. Superposed epoch analyses of such maps have demonstrated typical characteristics of ion heating during storms driven by coronal mass ejections as compared to those driven by high speed solar wind streams. The temperatures have been used to establish boundary conditions for modeling of the inner magnetosphere. We will give an overview of recent studies using TWINS ion temperature maps. Work supported by NNX10AN08A and AGS-1113478.

  8. Features of the Geomagnetic Variations In the Moscow Region

    Science.gov (United States)

    Riabova, Svetlana; Spivak, Alexander

    2017-04-01

    The results of instrumental observations indicate the presence of significant amplitude variations in Earth's magnetic field. The data obtained in the research of geomagnetic variations allow us to not only establish and classify their sources, but also to form the basis for the improvement and development of new source models of magnetospheric and ionospheric disturbances, new methods of magnetotelluric and magnetovariational sensing and diagnostic methods of geodynamic state of the Earth's crust and the research of meteorological processes in the atmosphere. In this research we used the results of instrumental observations of geomagnetic field, carried out in the period of 2009 - 2015 at Geophysical Observatory "Mikhnevo" of Institute of Geosphere Dynamics of Russian Academy of Sciences. The observatory (54,960N; 37,774E) is located in the Moscow region. The analysis shows that in general the geophysical situation in the Moscow region is disturbed. The tendency to increasing in geomagnetic activity over time is established (the number of days with a perturbed state of the geomagnetic field is increased by 7.6 times during the period of 2009 - 2015). Repeatability of geomagnetic disturbances is characterized by clearly pronounced periodicity with characteristic periods of about 14, 27, 60, 182 and 365 days.

  9. Longitudinal differences observed in the ionospheric F-region during the major geomagnetic storm of 31 March 2001

    Directory of Open Access Journals (Sweden)

    Y. Sahai

    2004-09-01

    Full Text Available A new ionospheric sounding station using a Canadian Advanced Digital Ionosonde (CADI was established for routine measurements by the "Universidade do Vale do Paraiba (UNIVAP" at São José dos Campos (23.2° S, 45.9° W, Brazil, in August 2000. A major geomagnetic storm with gradual commencement at about 01:00 UT was observed on 31 March 2001. In this paper, we present and discuss salient features from the ionospheric sounding measurements carried out at S. J. Campos on the three consecutive UT days 30 March (quiet, 31 March (disturbed and 1 April (recovery 2001. During most of the storm period, the foF2 values showed negative phase, whereas during the two storm-time peaks, large F-region height variations were observed. In order to study the longitudinal differences observed in the F-region during the storm, the simultaneous ionospheric sounding measurements carried out at S. J. Campos, El Arenosillo (37.1° N, 6.7° W, Spain, Okinawa (26.3° N, 127.8° E, Japan and Wakkanai (45.5° N, 141.7° E, Japan, during the period 30 March-1 April 2001, have been analyzed. A comparison of the observed ionospheric parameters (h'F and foF2 in the two longitudinal zones (1. Japanese and 2. Brazilian-Spanish shows both similarities and differences associated with the geomagnetic disturbances. Some latitudinal differences are also observed in the two longitudinal zones. In addition, global ionospheric TEC maps from the worldwide network of GPS receivers are presented, showing widespread TEC changes during both the main and recovery phases of the storm. The ionospheric sounding measurements are compared with the ASPEN-TIMEGCM model runs appropriate for the storm conditions. The model results produce better agreement during the quiet period. During the disturbed period, some of the observed F-region height variations are well reproduced by the model results. The model foF2 and TEC results differ considerably during the

  10. Geomagnetic storms can trigger stroke: evidence from 6 large population-based studies in Europe and Australasia.

    Science.gov (United States)

    Feigin, Valery L; Parmar, Priya G; Barker-Collo, Suzanne; Bennett, Derrick A; Anderson, Craig S; Thrift, Amanda G; Stegmayr, Birgitta; Rothwell, Peter M; Giroud, Maurice; Bejot, Yannick; Carvil, Phillip; Krishnamurthi, Rita; Kasabov, Nikola

    2014-06-01

    Although the research linking cardiovascular disorders to geomagnetic activity is accumulating, robust evidence for the impact of geomagnetic activity on stroke occurrence is limited and controversial. We used a time-stratified case-crossover study design to analyze individual participant and daily geomagnetic activity (as measured by Ap Index) data from several large population-based stroke incidence studies (with information on 11 453 patients with stroke collected during 16 031 764 person-years of observation) in New Zealand, Australia, United Kingdom, France, and Sweden conducted between 1981 and 2004. Hazard ratios and corresponding 95% confidence intervals (CIs) were calculated. Overall, geomagnetic storms (Ap Index 60+) were associated with 19% increase in the risk of stroke occurrence (95% CI, 11%-27%). The triggering effect of geomagnetic storms was most evident across the combined group of all strokes in those aged 50%: moderate geomagnetic storms (60-99 Ap Index) were associated with a 27% (95% CI, 8%-48%) increased risk of stroke occurrence, strong geomagnetic storms (100-149 Ap Index) with a 52% (95% CI, 19%-92%) increased risk, and severe/extreme geomagnetic storms (Ap Index 150+) with a 52% (95% CI, 19%-94%) increased risk (test for trend, Pstorms are associated with increased risk of stroke and should be considered along with other established risk factors. Our findings provide a framework to advance stroke prevention through future investigation of the contribution of geomagnetic factors to the risk of stroke occurrence and pathogenesis. © 2014 American Heart Association, Inc.

  11. A study on precursors leading to geomagnetic storms using artificial neural network

    Indian Academy of Sciences (India)

    Gaurav Singh; A K Singh

    2016-07-01

    Space weather prediction involves advance forecasting of the magnitude and onset time of major geomagneticstorms on Earth. In this paper, we discuss the development of an artificial neural network-basedmodel to study the precursor leading to intense and moderate geomagnetic storms, following halo coronalmass ejection (CME) and related interplanetary (IP) events. IP inputs were considered within a 5-daytime window after the commencement of storm. The artificial neural network (ANN) model training,testing and validation datasets were constructed based on 110 halo CMEs (both full and partial halo andtheir properties) observed during the ascending phase of the 24th solar cycle between 2009 and 2014. Thegeomagnetic storm occurrence rate from halo CMEs is estimated at a probability of 79%, by this model.

  12. Severe geomagnetic storms and Forbush decreases: interplanetary relationships reexamined

    Directory of Open Access Journals (Sweden)

    R. P. Kane

    2010-02-01

    Full Text Available Severe storms (Dst and Forbush decreases (FD during cycle 23 showed that maximum negative Dst magnitudes usually occurred almost simultaneously with the maximum negative values of the Bz component of interplanetary magnetic field B, but the maximum magnitudes of negative Dst and Bz were poorly correlated (+0.28. A parameter Bz(CP was calculated (cumulative partial Bz as sum of the hourly negative values of Bz from the time of start to the maximum negative value. The correlation of negative Dst maximum with Bz(CP was higher (+0.59 as compared to that of Dst with Bz alone (+0.28. When the product of Bz with the solar wind speed V (at the hour of negative Bz maximum was considered, the correlation of negative Dst maximum with VBz was +0.59 and with VBz(CP, 0.71. Thus, including V improved the correlations. However, ground-based Dst values have a considerable contribution from magnetopause currents (several tens of nT, even exceeding 100 nT in very severe storms. When their contribution is subtracted from Dst(nT, the residue Dst* representing true ring current effect is much better correlated with Bz and Bz(CP, but not with VBz or VBz(CP, indicating that these are unimportant parameters and the effect of V is seen only through the solar wind ram pressure causing magnetopause currents. Maximum negative Dst (or Dst* did not occur at the same hour as maximum FD. The time evolutions of Dst and FD were very different. The correlations were almost zero. Basically, negative Dst (or Dst* and FDs are uncorrelated, indicating altogether different mechanism.

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

    Science.gov (United States)

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

    2014-01-01

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

  14. Solar wind drivers of geomagnetic storms during more than four solar cycles

    Directory of Open Access Journals (Sweden)

    Richardson Ian G.

    2012-05-01

    Full Text Available Using a classification of the near-Earth solar wind into three basic flow types: (1 High-speed streams associated with coronal holes at the Sun; (2 Slow, interstream solar wind; and (3 Transient flows originating with coronal mass ejections (CMEs at the Sun, including interplanetary CMEs and the associated upstream shocks and post-shock regions, we determine the drivers of geomagnetic storms of various size ranges based on the Kp index and the NOAA “G” criteria since 1964, close to the beginning of the space era, to 2011, encompassing more than four solar cycles (20–23. We also briefly discuss the occurrence of storms since the beginning of the Kp index in 1932, in the minimum before cycle 17. We note that the extended low level of storm activity during the minimum following cycle 23 is without precedent in this 80-year interval. Furthermore, the “typical” numbers of storm days/cycle quoted in the standard NOAA G storm table appear to be significantly higher than those obtained from our analysis, except for the strongest (G5 storms, suggesting that they should be revised downward.

  15. General circulation modeling of the thermosphere-ionosphere during a geomagnetic storm

    Science.gov (United States)

    Yiǧit, Erdal; Immel, Thomas; Ridley, Aaron; Frey, Harald U.; Moldwin, Mark

    2016-07-01

    Using a three-dimensional general circulation model (GCM) of the upper atmosphere, we investigate the response of the thermosphere-ionosphere system to the August 2011 major geomagnetic storm. The GCM is driven by measured storm-time input data of the Interplanetary Magnetic Field (IMF), solar activity, and auroral activity. Simulations for quiet steady conditions over the same period are performed as well in order to assess the response of the neutral and plasma parameters to the storm. During the storm, the high-latitude mean ion flows are enhanced by up to ~150%. Overall, the global mean neutral temperature increases by up to 15%, while the maximum thermal response is higher in the winter Southern Hemisphere at high-latitudes than the summer Northern Hemisphere: 40% vs. 20% increase in high-latitude mean temperature, respectively. The global mean Joule heating of the neutral atmosphere increases by more than a factor of three. There are distinct hemispheric differences in the magnitude and morphology of the horizontal ion flows and thermospheric circulation during the different phases of the storm. The thermospheric circulation demonstrates the largest amount of hemispheric differences during the later stages of the storm. Dynamical diagnostics show that advective forcing contributes to hemispheric differences.

  16. A Carrington-like geomagnetic storm observed in the 21st century

    CERN Document Server

    Cid, C; Guerrero, A; Palacios, J; Cerrato, Y

    2015-01-01

    In September 1859 the Colaba observatory measured the most extreme geomagnetic disturbance ever recorded at low latitudes related to solar activity: the Carrington storm. This paper describes a geomagnetic disturbance case with a profile extraordinarily similar to the disturbance of the Carrington event at Colaba: the event on 29 October 2003 at Tihany magnetic observatory in Hungary. The analysis of the H-field at different locations during the "Carrington-like" event leads to a re-interpretation of the 1859 event. The major conclusions of the paper are the following: (a) the global Dst or SYM-H, as indices based on averaging, missed the largest geomagnetic disturbance in the 29 October 2003 event and might have missed the 1859 disturbance, since the large spike in the horizontal component (H) of terrestrial magnetic field depends strongly on magnetic local time (MLT); (b) the main cause of the large drop in H recorded at Colaba during the Carrington storm was not the ring current but field-aligned currents ...

  17. A Carrington-like geomagnetic storm observed in the 21st century

    Directory of Open Access Journals (Sweden)

    Cid Consuelo

    2015-01-01

    Full Text Available In September 1859 the Colaba observatory measured the most extreme geomagnetic disturbance ever recorded at low latitudes related to solar activity: the Carrington storm. This paper describes a geomagnetic disturbance case with a profile extraordinarily similar to the disturbance of the Carrington event at Colaba: the event on 29 October 2003 at Tihany magnetic observatory in Hungary. The analysis of the H-field at different locations during the “Carrington-like” event leads to a re-interpretation of the 1859 event. The major conclusions of the paper are the following: (a the global Dst or SYM-H, as indices based on averaging, missed the largest geomagnetic disturbance in the 29 October 2003 event and might have missed the 1859 disturbance, since the large spike in the horizontal component (H of terrestrial magnetic field depends strongly on magnetic local time (MLT; (b the main cause of the large drop in H recorded at Colaba during the Carrington storm was not the ring current but field-aligned currents (FACs; and (c the very local signatures of the H-spike imply that a Carrington-like event can occur more often than expected.

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

    Indian Academy of Sciences (India)

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

    2016-04-01

    The geomagnetic storm of November 1998 is a unique event where IMF-Bz remained southward withvalues exceeding –15 nT for more than a day. The SYM/H index decreased from about 07 hr on 13November 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 eventof 13–14 November 1998, based on the geomagnetic data from the chain of observatories in India. Suddennorthward turning of IMF-Bz for a very short duration around 08 hr on 13 November 1998 resultedin a small and very short duration counter electrojet. A strong (–50 nT) and a long duration counterelectrojet, right from 08 to 13 hr on 14 November 1998 was observed resulting in the absence of equatorialEs at Thumba. Absence of the equatorial ionization anomaly was also observed as seen from theionograms over Thumba and ionspheric data from Ahmedabad. The delayed effect on 14 November 1998is due to the disturbance dynamo effect.

  19. An Investigation of Geomagnetic Storms and Associated Cosmic Ray Intensity During Recent Solar Cycle

    Science.gov (United States)

    Kaushik, Sonia

    2016-07-01

    Shocks driven by energetic coronal mass ejections (CME's) and other interplanetary (IP) transients are mainly responsible for initiating large and intense geomagnetic storms. Observational results indicate that galactic cosmic rays (CR) coming from deep surface interact with these abnormal solar and IP conditions and suffer modulation effects. The current solar cycle has provided a long list of these highly energetic events influencing the Earth's geomagnetic field up to a great extent. We have selected such intense geo-effective CME's occurred during recent solar cycle and studied their possible influence on cosmic ray intensity as well as on Earth' s geomagnetic field using the hourly values of IMF data obtained from the NSSD Center. Solar wind data obtained from various satellites are used in the studies which are available during the selected events period. The super neutron monitor data obtained from Kiel, Oulu and Huancayo stations, well distributed over different latitudes has been used in the present study. It is found that AP and AE indices show rise before the forward turnings of IMF and both the Dst index and cosmic ray intensity show a classic decrease. The analysis further indicates the significant role of the magnitudes of Bz component of IMF substantiating the earlier results. It is further inferred that the magnitude of these responses depends on BZ component of IMF being well correlated with solar maximum and minimum periods. Transient decrease in cosmic ray intensity with slow recovery is observed during the storm phase duration.

  20. Hemispheric Differences in the Response of the Upper Atmosphere to the August 2011 Geomagnetic Storm: A Simulation Study

    OpenAIRE

    Yiğit, Erdal; Frey, Harald U.; Moldwin, Mark B.; Immel, Thomas J.; Ridley, Aaron J.

    2015-01-01

    Using a three-dimensional nonhydrostatic general circulation model, we investigate the response of the thermosphere-ionosphere system to the 5-6 August 2011 major geomagnetic storm. The model is driven by measured storm-time input data of the Interplanetary Magnetic Field (IMF), solar activity, and auroral activity. Simulations for quiet steady conditions over the same period are performed as well in order to assess the response of the neutral and plasma parameters to the storm. During the st...

  1. Study of atomic oxygen greenline dayglow emission in thermosphere during geomagnetic storm conditions

    Science.gov (United States)

    Bag, T.; Singh, Vir; Sunil Krishna, M. V.

    2017-01-01

    The influence of geomagnetic storms on the atomic oxygen greenline (557.7 nm) dayglow emission in thermosphere is studied during solar active and solar quiet conditions. This study is primarily based on the photochemical model with inputs obtained from experimental observations and empirical models. The updated rate coefficients, quantum yields and related cross-sections have been used from experimental results and theoretical studies. This study is presented for a low latitude station Tirunelveli (8.7°N, 77.8°E), India. The volume emission rate (VER) has been calculated using densities and temperatures from the empirical models. The modeled VER shows a positive correlation with the Dst index. The VER also shows a negative correlation with the number densities of O, O2, and N2. The VER, calculated at peak emission altitude, exhibits depletion during the main phase of the storm. The altitude of peak emission rate is unaffected by the geomagnetic storm activity. The study also reveals that the peak emission altitude depends on the F10.7 solar index. The peak emission altitude moves upward as the value of F10.7 solar index increases.

  2. Plasma and Magnetic Field Characteristics of Solar Coronal Mass Ejections in Relation to Geomagnetic Storm Intensity and Variability

    CERN Document Server

    Liu, Ying D; Wang, Rui; Yang, Zhongwei; Zhu, Bei; Liu, Yi A; Luhmann, Janet G; Richardson, John D

    2015-01-01

    The largest geomagnetic storms of solar cycle 24 so far occurred on 2015 March 17 and June 22 with $D_{\\rm st}$ minima of $-223$ and $-195$ nT, respectively. Both of the geomagnetic storms show a multi-step development. We examine the plasma and magnetic field characteristics of the driving coronal mass ejections (CMEs) in connection with the development of the geomagnetic storms. A particular effort is to reconstruct the in situ structure using a Grad-Shafranov technique and compare the reconstruction results with solar observations, which gives a larger spatial perspective of the source conditions than one-dimensional in situ measurements. Key results are obtained concerning how the plasma and magnetic field characteristics of CMEs control the geomagnetic storm intensity and variability: (1) a sheath-ejecta-ejecta mechanism and a sheath-sheath-ejecta scenario are proposed for the multi-step development of the 2015 March 17 and June 22 geomagnetic storms, respectively; (2) two contrasting cases of how the CM...

  3. De-noising Diurnal Variation Data in Geomagnetic Field Modelling

    Science.gov (United States)

    Onovughe, E.

    2017-01-01

    Ground based geomagnetic observatory series have been used to investigate and describe the residuals between a continuous geomagnetic field model and observed diurnal variation for noise-removal of signal due to external field of magnetospheric ring current sources. In all the observatories studied, the residuals in the X-direction consistently show the noisiest signal. Results show that the residuals in the X-direction correlates closely with the RC-index, suggesting an origin from unmodelled external field variation. Notable cross-correlation is also seen between the residuals and the RC-index at zero-lag. Removal/reduction of this unmodelled signal enhances resolution of fine-scale detail in diurnal variation studies.

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

    Science.gov (United States)

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

    magnetic storms. Using the combination of the wavelet transform and neural networks, we have developed a technique of approximating the time variation of cosmic-ray data. This technique allows us to perform detailed analysis of geomagnetic data and detect anomalies in periods of high solar activity. Approximations of large-scale time variation components of cosmic-ray data have been obtained in the following form: [ c_{j,n+1}(t)=\\varphi^3_m Biggl (sum_i omega^3_{mi}\\varphi^2_i biggl (sum_l omega^2_{il}\\varphi^1_lBigl(sum_n omega^1_{ln}c_{j,n}(t)Bigr )biggr ) Biggr ) ] where c_{j,n}= ;phi_{j,n}=2(j/2) phi(2(j(t)-n)) is the scaling function, omega(1_{ln}) are the weights of the neurons of the network input layer l,omega(2_{il}) are the weights of the neurons of the network hidden layer i, omega(3_{mi}) are the weights of the neurons of the network output layer m, varphi(1_l(z)=varphi^2_i(z)=(2)/(1+exp(-2z))-1) ,varphi(3_m(z)) =a*z+b. Coefficients c_{j,n} are the result of transforming of the original function y to the space with the scale j. Analysis of long geomagnetic data from the Paratunka observatory (Kamchatka region, Russia) provided quantitative estimates of the storminess degree of the geomagnetic field before and during magnetic storms. Furthermore, we have managed to identify local weak increases of the field perturbations prior to the main phase of storms. The intensity of field perturbations rises on average 2.5 days before the onset of a storm. Abnormal time periods connected with increased solar activity have been detected in the flow of cosmic rays. Comparison of the results with the geomagnetic data has shown that the anomalies in the cosmic ray variations occur in periods of strong geomagnetic perturbations. The tools and techniques suggested in the present work, together with other methods of data -analysis will help forecast space weather, estimate more accurately the condition of the Earth’s magnetic field, and identify periods when the intensity of

  5. Structuring of intermediate scale equatorial spread F irregularities during intense geomagnetic storm of solar cycle 24

    Science.gov (United States)

    Kakad, B.; Gurram, P.; Tripura Sundari, P. N. B.; Bhattacharyya, A.

    2016-07-01

    Here we examine the structuring of equatorial plasma bubble (EPB) during intense geomagnetic storm of solar cycle (SC) 24 that occurred on 17 March 2015 using spaced receiver scintillation observations on a 251 MHz radio signal, recorded by a network of stations in Indian region. As yet, this is the strongest geomagnetic storm (Dstmin˜-223nT) that occurred in present SC. Present study reveals that the structuring of equatorial spread F (ESF) irregularities was significantly different on 17 March as compared to quiet days of corresponding month. ESF irregularities of intermediate scale (100 m to few kilometers) are observed at unusually higher altitudes (≥ 800 km) covering wider longitudinal-latitudinal belt over Indian region. A presence of large-scale irregularity structures with stronger ΔN at raised F peak with small-scale irregularities at even higher altitudes is observed. It caused strong focusing effect (S4>1) that prevails throughout premidnight hours at dip equatorial station Tirunelveli. Other observational aspect is that zonal irregularity drifts over low-latitude station Kolhapur exhibited a large deviation of ˜230 m/s from their average quiet time pattern. During this geomagnetic storm, two southward turnings of significant strength (BZ≤-15 nT) occurred at 11.4 IST (Indian standard time) and 17.9 IST. The later southward turning of interplanetary magnetic field (IMF)BZ resulted in a large eastward prompt penetration electric field (PPEF) close to sunset hours in Indian longitude. Estimates of PPEF obtained from real-time ionospheric model are too low to explain the observed large upliftment of F region in the post sunset hours. Possible reason for observed enhanced PPEF-linked effects is discussed.

  6. Numerical Modeling of Auroral and Equatorial Electrojet Behavior during Geomagnetic Storm Sequence on September 9-14, 2005

    Science.gov (United States)

    Klimenko, Maxim; Klimenko, Vladimir

    In Klimenko et al., 2006 the model of electric field and zonal current in the Earth's ionosphere has been presented. This model has been included into the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) developed in WD IZMIRAN (Namgaladze et al., 1988). The modified GSM TIP model has allowed to describe more correctly the behavior of electric field and different ionospheric parameters at low latitudes, and also to investigate the behavior of auroral and equatorial electrojets. In the given research we present the calculation results of behavior of auroral and equatorial electrojets during geomagnetic storm sequence on September 9-14, 2005. The calculations have been executed with use of the modified GSM TIP model. At that the model input parameters, such as the potential difference through polar caps, field-aligned currents of second region and particle precipitation fluxes and energy were set as function of AE-and Kp-indices of geomagnetic activity according to different empirical models Feshchenko and Maltsev, 2003; Zhang and Paxton, 2008 and morphological representations Cheng et al., 2008. Furthermore, at the storm sudden commencement phase we taken into account the shift of field-aligned currents of the second region into the lower latitudes as by Sojka et al., 1994 and 30 min. time delay of variations of the field-aligned currents of the second region relative to the variations of the potential drop through polar caps. Also, we taken into account the ionospheric effects of solar flares, which were taken place during the considered period. The calculation results are analyzed according to known morphological representations about auroral and equatorial electrojet behavior during geomagnetic storms. This study is supported by RFBR grant 08-05-00274. References Cheng Z.W., Shi J.K., Zhang T.L., Dunlop M. and Liu Z.X. Relationship between FAC at plasma sheet boundary layers and AE index during storms from August to October

  7. Role of the magnetospheric and ionospheric currents in the generation of the equatorial scintillations during geomagnetic storms

    Directory of Open Access Journals (Sweden)

    L. Z. Biktash

    2004-09-01

    Full Text Available The equatorial ionosphere parameters, Kp, Dst, AU and AL indices characterized contribution of different magnetospheric and ionospheric currents to the H-component of geomagnetic field are examined to test the geomagnetic activity effect on the generation of ionospheric irregularities producing VLF scintillations. According to the results of the current statistical studies, one can predict near 70% of scintillations from Aarons' criteria using the Dst index, which mainly depicts the magnetospheric ring current field. To amplify Aarons' criteria or to propose new criteria for predicting scintillation characteristics is the question. In the present phase of the experimental investigations of electron density irregularities in the ionosphere new ways are opened up because observations in the interaction between the solar wind - magnetosphere - ionosphere during magnetic storms have progressed greatly. According to present view, the intensity of the electric fields and currents at the polar regions, as well as the magnetospheric ring current intensity, are strongly dependent on the variations of the interplanetary magnetic field. The magnetospheric ring current cannot directly penetrate the equatorial ionosphere and because of this difficulties emerge in explaining its relation to scintillation activity. On the other hand, the equatorial scintillations can be observed in the absence of the magnetospheric ring current. It is shown that in addition to Aarons' criteria for the prediction of the ionospheric scintillations, models can be used to explain the relationship between the equatorial ionospheric parameters, h'F, foF2, and the equatorial geomagnetic variations with the polar ionosphere currents and the solar wind.

  8. 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

    Science.gov (United States)

    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

  9. Studies of ionospheric variations during geomagnetic activities at the low-latitude station, Ile-Ife, Nigeria

    Science.gov (United States)

    Emmanuel, Ariyibi

    The dual frequency SCINDA NovAtel GSV 4004B GPS receiver installed at the Ile-Ife (low-latitude station) has been in operation since December 2009. Data records for the year 2010 were processed to obtain Total Electron Content (TEC) and S 4 index. These were interpreted to analyze the ionospheric condition during low geomagnetic activity period (when Dst is from -40 to 0 nT) and during geomagnetic storm events (with Dst about -100 nT). Seasonal variations of the TEC and S 4 index were also investigated. The occurrence of scintillations is closely linked to the peak value of TEC during the daytime; this is very evident during the equinox months when TEC ≥ 30 TECu. When the maximum TEC value is below 30 TECu, as shown by most of the days in the summer months, the scintillation phenomenon does not occur. During geomagnetic storms, the daytime segment of the TEC plot experiences fluctuations (even bifurcations) in values with the peak TEC value of about 40 TECu. From the interpreted data, the occurrence of geomagnetic storm does not necessarily suggest an increase in the level of scintillations at a low-latitude region. Also, there is a remarkable difference between the IRI 2007 model and the observed TEC values, as the daytime TEC peak differs in magnitude and time of occurrence from the observed TEC.

  10. A time-compressed simulated geomagnetic storm influences the nest-exiting flight angles of the stingless bee Tetragonisca angustula.

    Science.gov (United States)

    Esquivel, D M S; Corrêa, A A C; Vaillant, O S; de Melo, V Bandeira; Gouvêa, G S; Ferreira, C G; Ferreira, T A; Wajnberg, E

    2014-03-01

    Insects have been used as models for understanding animal orientation. It is well accepted that social insects such as honeybees and ants use different natural cues in their orientation mechanism. A magnetic sensitivity was suggested for the stingless bee Schwarziana quadripunctata, based on the observation of a surprising effect of a geomagnetic storm on the nest-exiting flight angles. Stimulated by this result, in this paper, the effects of a time-compressed simulated geomagnetic storm (TC-SGS) on the nest-exiting flight angles of another stingless bee, Tetragonisca angustula, are presented. Under an applied SGS, either on the horizontal or vertical component of the geomagnetic field, both nest-exiting flight angles, dip and azimuth, are statistically different from those under geomagnetic conditions. The angular dependence of ferromagnetic resonance (FMR) spectra of whole stingless bees shows the presence of organized magnetic nanoparticles in their bodies, which indicates this material as a possible magnetic detector.

  11. Geomagnetic variations and middle latitude IMF in periods of magnetic quietness

    Science.gov (United States)

    Ivanova, P. K.; Kleimenova, N. G.

    The slight variations of the midlatitude geomagnetic field during quiet and slightly disturbed periods are studied. These variations serve as the background of the powerful nonlinear processes of strong magnetic storms. An analysis is presented of the relationship between the variations of the magnetic field H-component at the Panagyurishte Observatory (phi = 41 deg, lambda = 103 deg) during relatively quiet magnetic periods preceding the sudden commencement of magnetic storms with the variations of the energy entering the magnetosphere and the variations of the solar wind parameters, B(z) and B(y). The quiet diurnal values are obtained from the observed hourly values of the H-component of the field and the rate of variation of the quiet diurnal value is analyzed. A regression analysis is performed of the variability, the hourly variations of delta-B(z) and delta-B(y), and the velocity variations of the energy entering the magnetosphere. Examples are given of the results obtained from these analyses.

  12. Solar and auroral evidence for an intense recurrent geomagnetic storm during December in AD 1128

    Energy Technology Data Exchange (ETDEWEB)

    Willis, D.M. [Warwick Univ., Coventry (United Kingdom). Dept. of Physics; Stephenson, F.R. [Durham Univ. (United Kingdom). Dept. of Physics

    2001-03-01

    The earliest known drawing of sunspots appears in The Chronicle of John of Worcester, which was compiled in the first half of the twelfth century. In this medieval chronicle, the Latin text describing the sunspots is accompanied by a colourful drawing, albeit idealised, which shows the apparent positions and sizes of two sunspots on the solar disk. The date of this observation of sunspots from Worcester, England is firmly established as AD 1128 December 8. Assuming that the drawing was prepared fairly carefully, the angular diameters of the two sunspots are at least about 3 arcmin and 2 arcmin in the northern and southern hemispheres, respectively. Similarly, the heliographic latitudes of both sunspots are within the approximate range of 25 -35 . About five days after this observation of sunspots on the solar disk, on the night of AD 1128 December 13, a red auroral display was observed from Songdo, Korea (the modern city of Kaesong). This auroral observation was recorded in the Koryo-sa, the official Korean chronicle of the period. In addition, five Chinese and five Korean descriptions of auroral displays were recorded in various East-Asian histories between the middle of AD 1127 and the middle of AD 1129. The ten oriental auroral records in this particular interval correspond to six distinct auroral events, which provide evidence for recurrent, though possibly intermittent, auroral activity on a timescale almost exactly equal to the synodic-solar-rotation period (approximately 27 days). The six distinct auroral events were apparently associated with two series of recurrent geomagnetic storms, both of which were sufficiently intense to produce mid-latitude auroral displays in East Asia. These ancient solar and auroral observations are interpreted in terms of present-day understanding of solar-terrestrial physics. Contemporary ground-based and satellite measurements during the last few decades have indicated that recurrent geomagnetic storms are usually a feature of

  13. [Geomagnetic storm decreases coherence of electric oscillations of human brain while working at the computer].

    Science.gov (United States)

    Novik, O B; Smirnov, F A

    2013-01-01

    The effect of geomagnetic storms at the latitude of Moscow on the electric oscillations of the human brain cerebral cortex was studied. In course of electroencephalogram measurements it was shown that when the voluntary persons at the age of 18-23 years old were performing tasks using a computer during moderate magnetic storm or no later than 24 hrs after it, the value of the coherence function of electric oscillations of the human brain in the frontal and occipital areas in a range of 4.0-7.9 Hz (so-called the theta rhythm oscillations of the human brain) decreased by a factor of two or more, sometimes reaching zero, although arterial blood pressure, respiratory rate and the electrocardiogram registered during electroencephalogram measurements remained within the standard values.

  14. Regional differences of the ionospheric response to the July 2012 geomagnetic storm

    Science.gov (United States)

    Kuai, Jiawei; Liu, Libo; Lei, Jiuhou; Liu, Jing; Zhao, Biqiang; Chen, Yiding; Le, Huijun; Wang, Yungang; Hu, Lianhuan

    2017-04-01

    The July 2012 geomagnetic storm is an extreme space weather event in solar cycle 24, which is characterized by a southward interplanetary geomagnetic field lasting for about 30 h below -10 nT. In this work, multiple instrumental observations, including electron density from ionosondes, total electron content (TEC) from Global Positioning System, Jason-2, and Gravity Recovery and Climate Experiment, and the topside ion concentration observed by the Defense Meteorological Satellite Program spacecraft are used to comprehensively present the regional differences of the ionospheric response to this event. In the Asian-Australian sector, an intensive negative storm is detected near longitude 120°E on 16 July, and in the topside ionosphere the negative phase is mainly existed in the equatorial region. The topside and bottomside TEC contribute equally to the depletion in TEC, and the disturbed electric fields make a reasonable contribution. On 15 July, the positive storm effects are stronger in the Eastside than in the Westside. The topside TEC make a major contribution to the enhancement in TEC for the positive phases, showing the important role of the equatorward neutral winds. For the American sector, the equatorial ionization anomaly intensification is stronger in the Westside than in the Eastside and shows the strongest feature in the longitude 110°W. The combined effects of the disturbed electric fields, composition disturbances, and neutral winds cause the complex storm time features. Both the topside ion concentrations and TEC reveal the remarkable hemispheric asymmetry, which is mainly resulted from the asymmetry in neutral winds and composition disturbances.

  15. Geomagnetic Core Field Secular Variation Models

    DEFF Research Database (Denmark)

    Gillet, N.; Lesur, V.; Olsen, Nils

    2010-01-01

    We analyse models describing time changes of the Earth’s core magnetic field (secular variation) covering the historical period (several centuries) and the more recent satellite era (previous decade), and we illustrate how both the information contained in the data and the a priori information...... highlight the difficulty of resolving the time variability of the high degree secular variation coefficients (i.e. the secular acceleration), arising for instance from the challenge to properly separate sources of internal and of external origin. In addition, the regularisation process may also result...

  16. Geographical localisation of the geomagnetic secular variation

    DEFF Research Database (Denmark)

    Aubert, Julien; Finlay, Chris; Olsen, Nils

    2013-01-01

    , westward moving, magnetic flux patches at the core surface. Despite its successes in explaining the main morphological properties of Earth’s magnetic field, self-consistent numerical modelling of the geodynamo has so far failed to reproduce this field variation pattern. Furthermore its magnetohydrodynamic...

  17. A study of geomagnetic field variations along the 80° S geomagnetic parallel

    Science.gov (United States)

    Lepidi, Stefania; Cafarella, Lili; Francia, Patrizia; Piancatelli, Andrea; Pietrolungo, Manuela; Santarelli, Lucia; Urbini, Stefano

    2017-01-01

    The availability of measurements of the geomagnetic field variations in Antarctica at three sites along the 80° S geomagnetic parallel, separated by approximately 1 h in magnetic local time, allows us to study the longitudinal dependence of the observed variations. In particular, using 1 min data from Mario Zucchelli Station, Scott Base and Talos Dome, a temporary installation during 2007-2008 Antarctic campaign, we investigated the diurnal variation and the low-frequency fluctuations (approximately in the Pc5 range, ˜ 1-7 mHz). We found that the daily variation is clearly ordered by local time, suggesting a predominant effect of the polar extension of midlatitude ionospheric currents. On the other hand, the pulsation power is dependent on magnetic local time maximizing around magnetic local noon, when the stations are closer to the polar cusp, while the highest coherence between pairs of stations is observed in the magnetic local nighttime sector. The wave propagation direction observed during selected events, one around local magnetic noon and the other around local magnetic midnight, is consistent with a solar-wind-driven source in the daytime and with substorm-associated processes in the nighttime.

  18. Ionosphere data assimilation capabilities for representing the high-latitude geomagnetic storm event in September 2011

    Science.gov (United States)

    Solomentsev, Dmitry; Jacobsen, Knut Stanley; Khattatov, Boris; Khattatov, Vyacheslav; Cherniak, Yakov; Titov, Anton

    2014-12-01

    Severe geomagnetic storms have a strong impact on space communication and satellite navigation systems. Forecasting the appearance of geomagnetically induced disturbances in the ionosphere is one of the urgent goals of the space weather community. The challenge is that the processes governing the distribution of the crucial ionospheric parameters have a rather poor quantitative description, and the models, built using the empirical parameterizations, have limited capabilities for operational purposes. On the other hand, data assimilation techniques are becoming more and more popular for nowcasting the state of the large-scale geophysical systems. We present an example of an ionospheric data assimilation system performance assessment during a strong geomagnetic event, which took place on 26 September 2011. The first-principle model has assimilated slant total electron content measurements from a dense network of ground stations, provided by the Norwegian Mapping Authority. The results have shown satisfactory agreement with independent data and demonstrate that the assimilation model is accurate to about 2-4 total electron content units and can be used for operational purposes in high-latitude regions. The operational system performance assessment is the subject of future work.

  19. Geomagnetic Secular Variation Prediction with Thermal Heterogeneous Boundary Conditions

    Science.gov (United States)

    Kuang, Weijia; Tangborn, Andrew; Jiang, Weiyuan

    2011-01-01

    It has long been conjectured that thermal heterogeneity at the core-mantle boundary (CMB) affects the geodynamo substantially. The observed two pairs of steady and strong magnetic flux lobes near the Polar Regions and the low secular variation in the Pacific over the past 400 years (and perhaps longer) are likely the consequences of this CMB thermal heterogeneity. There are several studies on the impact of the thermal heterogeneity with numerical geodynamo simulations. However, direct correlation between the numerical results and the observations is found very difficult, except qualitative comparisons of certain features in the radial component of the magnetic field at the CMB. This makes it difficult to assess accurately the impact of thermal heterogeneity on the geodynamo and the geomagnetic secular variation. We revisit this problem with our MoSST_DAS system in which geomagnetic data are assimilated with our geodynamo model to predict geomagnetic secular variations. In this study, we implement a heterogeneous heat flux across the CMB that is chosen based on the seismic tomography of the lowermost mantle. The amplitude of the heat flux (relative to the mean heat flux across the CMB) varies in the simulation. With these assimilation studies, we will examine the influences of the heterogeneity on the forecast accuracies, e.g. the accuracies as functions of the heterogeneity amplitude. With these, we could be able to assess the model errors to the true core state, and thus the thermal heterogeneity in geodynamo modeling.

  20. The ionospheric response to perturbation electric fields during the onset phase of geomagnetic storms

    Energy Technology Data Exchange (ETDEWEB)

    Jakowski, N.; Jungstand, A. (Deutsche Forschungsanstalt fuer Luft- and Raumfahrt, Neustrelitz (Germany)); Schlegel, K.; Kohl, H.; Rinnert, K. (Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany))

    1992-07-01

    The generation and propagation of ionospheric storms are studied by analyzing EISCAT radar, and vertical sounding and total electron content data obtained under different geophysical conditions. Both case studies as well as the average storm pattern of percentage deviations of different ionospheric parameters from their corresponding reference values such as total electron content, F2-layer critical frequency, F2 layer critical height, and slab thickness indicate the action of a perturbation electric field during the first few hours of the onset of geomagnetic storms. Considering the onset phase of the storm on July 28-29, 1987 evidence has been found that high latitude electric fields may penetrate to lower latitudes before the ring current has developed. Different mechanisms are assumed to be responsible for daytime and nightime behaviour, respectively. The negative phase propagates equatorward with velocities in the order of 70-350 m/s following a strong heating of the thermosphere and ionosphere due to the auroral electrojet. 24 refs., 10 figs.

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

    Science.gov (United States)

    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

  2. The first super geomagnetic storm of solar cycle 24: "The St. Patrick's day event (17 March 2015)"

    Science.gov (United States)

    Wu, Chin-Chun; Liou, Kan; Lepping, Ronald P.; Hutting, Lynn; Plunkett, Simon; Howard, Russ A.; Socker, Dennis

    2016-09-01

    The first super geomagnetic storm (Dst radio bursts. The initial propagation speed of this CME is estimated to be ~668 km/s. An interplanetary (IP) shock, likely driven by a magnetic cloud (MC), arrived at the Wind spacecraft at 03:59 UT on 17 March and caused a sudden storm commencement. The storm intensified during the Earth's crossing of the ICME/shock sheath and then recovered slightly after the interplanetary magnetic field (IMF) turned northward. The IMF started turning southward again due to a large MC field itself, which caused the second storm intensification, reaching a minimum value (Dst = -223 nT). It is found that the first step is caused by a southward IMF component in the sheath (between the upstream shock and the front of the MC), whereas the second step is associated with the passage of the MC. The CME that erupted on 15 March is the sole solar source of the MC. We also discuss the CME/storm event with detailed data from observations ( Wind and SOHO) and our algorithm for predicting the intensity of a geomagnetic storm (Dstmin) from known IP parameter values. We found that choosing the correct Dstmin estimating formula for predicting the intensity of MC-associated geomagnetic storms is crucial for space weather predictions.

  3. Multiwavelength Study on Solar and Interplanetary Origins of the Strongest Geomagnetic Storm of Solar Cycle 23

    CERN Document Server

    Kumar, Pankaj; Uddin, Wahab

    2011-01-01

    We study the solar sources of an intense geomagnetic storm of solar cycle 23 that occurred on 20 November 2003, based on ground- and space-based multiwavelength observations. The coronal mass ejections (CMEs) responsible for the above geomagnetic storm originated from the super-active region NOAA 10501. We investigate the H-alpha observations of the flare events made with a 15 cm solar tower telescope at ARIES, Nainital, India. The propagation characteristics of the CMEs have been derived from the three-dimensional images of the solar wind (i.e., density and speed) obtained from the interplanetary scintillation data, supplemented with other ground- and space-based measurements. The TRACE, SXI and H-alpha observations revealed two successive ejections (of speeds ~350 and ~100 km/s), originating from the same filament channel, which were associated with two high speed CMEs (~1223 and ~1660 km/s, respectively). These two ejections generated propagating fast shock waves (i.e., fast drifting type II radio bursts) ...

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

    Science.gov (United States)

    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. Effects of Geomagnetic Storms and Sudden Stratospheric Warmings on Mesosphere and Lower Thermosphere Winds

    Science.gov (United States)

    Wu, Q.; Gablehouse, R. D.; Gell, D. A.; Johnson, R. M.; Kafkalidis, J. F.; Killeen, T. L.; Niciejewski, R. J.; Ortland, D. A.; Skinner, W. R.; Solomon, S. C.

    2003-12-01

    Neutral winds in the MLT region are affected by dynamical influences from above and below. This is particular true at high latitudes, where solar forcing of the migrating tide may be smaller but other forcings play a big role. During geomagnetic storms, MLT neutral winds can be driven by magnetospheric convection through ion-neutral interactions. This is imparted onto the ionosphere as a cross polar cap potential forming an anti-sunward two-cell ion convection pattern which in turn drives the neutral winds in the polar MLT region. The question has always been how deep into the atmosphere the ion drift can affect the neutral wind. Scarcity of high-latitude data has hampered further understanding of the problem. Also, in the winter polar regions, the stratosphere from time to time experiences sudden warming events. While it is generally understood that these warmings are caused by troposphere planetary wave activity, there are still many unknown aspects to their excitation and propagation. There are also changes in the MLT region associated with these warming events. Moreover, this phenomena, although usually confined to the northern hemisphere, occurred in the southern hemisphere in 2002. We will use TIDI data to examine MLT neutral winds during the recent geomagnetic storm events in 2002 and 2003, and present data during the recent 2002 southern hemisphere warming event.

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

    Science.gov (United States)

    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.

  7. Analysis of High-Latitude lonospheric Processes During HSS and CME-Induced Geomagnetic Storms

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga

    For the first time we compared ionospheric effects of HSS and CME-driven storms at high-latitudes. There were similarities and also differences observed in the development of the storms. (1) Both type of storms exhibited clear negative phase, which resulted in an increase of TOI......-breaking-down into patches and a decrease in patch formation in general throughout the Greenland sector. The negative phase developed as the PCN-index started to increase indicated energy input into the polarcap. (2) The rate of PCN increase was clearly different for the two types of storms. (3) The impact of the physical...... processes responsible for the negative phase have less pronounced impact on the diurnal TEC variations than on patch formation. We also investigated and assessed storm influences on airborne navigation at high-latitudes in order to determine the possible cause of the radio communication disturbances...

  8. NM-MT network and space dangerous phenomena, 2. Examples of cosmic ray using for forecasting of major geomagnetic storms

    Science.gov (United States)

    Belov, A.; Dorman, L.; Eroshenko, E.; Iucci, N.; Parisi, M.; Pustil Nik, L.; Sternlieb, A.; Villoresi, G.; Yanke, V.; Zukerman, I.

    We present developing of methods (e.g., Dorman et al., 1995, 1999) for forecasting on the basis of neutron monitor hourly on-line data (as well as on-line muon telescopes hourly data from different directions) geomagnetic storms of scales G5 (3- hour index of geomagnetic activity Kp=9), G4 (Kp=8) and G3 (Kp=7) (according to NOAA Space Weather Scales). These geomagnetic storms are dangerous for people technology and health (influence on power systems, on spacecraft operations, on HF radio-communications and others). We show that for especially dangerous geomagnetic storms can be used global-spectrographic method if on-line will be available 35-40 NM and muon telescopes. In this case for each hour can be determined CR anisotropy vector, and the specifically behavior of this vector before SC of geomagnetic storms G5, G4 or G3 (according to NOAA Space Weather Scales) can be used as important factor for forecast. The second factor what can be used for SC forecast is specifically behavior of CR density (CR intensity) for about 30-15 hours before SC (caused mainly by galactic CR particles acceleration during interaction with shock wave moved from the Sun). The third factor is effect of cosmic ray pre-decreasing, caused by magnetic connection of the Earth with the region behind the shock wave. We demonstrate developing methods on several examples of major geomagnetic storms. This research is partly supported by the INTAS grant 00-0810. REFERENCES: Dorman L.I., et al. "Cosmic-ray forecasting features for big Forbush-decreases". Nuclear Physics B, 49A, 136-144 (1995). L.I.Dorman, et al, "Cosmic ray Forbush-decrease as indicators of space dangerous phenomenon and possible use of cosmic ray data for their prediction", Proc. of 26-th Intern. Cosmic Ray Conference, Salt Lake City, 6, 476-479 (1999).

  9. Modelling of ionospheric irregularities during geomagnetic storms over African low latitude region

    Science.gov (United States)

    Mungufeni, Patrick

    2016-07-01

    In this study, empirical models of occurrence of ionospheric irregularities over low latitude African region during geomagnetic storms have been developed. The geomagnetic storms considered consisted of Dst ≤ -50 nT. GNSS-derived ionospheric Total Electron Content (TEC) data over Libreville, Gabon (NKLG) (0.35° N, 9.68° E, geographic, 8.05° S, magnetic) and Malindi, Kenya (MAL2) (2.99° S, 40.19° E, geographic, 12.42° S, magnetic) during 2000 - 2014 were used. Ionospheric irregularities at scale- lengths of a few kilometers and ˜400 m were represented with the rate of change of TEC index (ROTI). The inputs for the models are the local time, solar flux index, Auroral Electrojet index, day of the year, and the Dst index, while the output is the median ROTI during these given conditions. To develop the models, the ROTI index values were binned based on the input parameters and cubic B splines were then fitted to the binned data. Developed models using data over NKLG and MAL2 were validated with independent data over stations within 510 km and 680 km radius, respectively. The models captured the enhancements and inhibitions of the occurrence of the ionospheric irregularities during the storm period. The models even emulated these patterns in the various seasons, during medium and high solar activity conditions. The correlation coefficients for the validations were statistically significant and ranged from 0.58 - 0.73, while the percentage of the variance in the observed data explained by the modelled data ranged from 34 - 53.

  10. Large enhancements in low latitude total electron content during 15 May 2005 geomagnetic storm in Indian zone

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2009-05-01

    Full Text Available Results pertaining to the response of the equatorial and low latitude ionosphere to a major geomagnetic storm that occurred on 15 May 2005 are presented. These results are also the first from the Indian zone in terms of (i GPS derived total electron content (TEC variations following the storm (ii Local low latitude electrodynamics response to penetration of high latitude convection electric field (iii effect of storm induced traveling atmospheric disturbances (TAD's on GPS-TEC in equatorial ionization anomaly (EIA zone.

    Data set comprising of ionospheric TEC obtained from GPS measurements, ionograms from an EIA zone station, New Delhi (Geog. Lat. 28.42° N, Geog. Long. 77.21° E, ground based magnetometers in equatorial and low latitude stations and solar wind data obtained from Advanced Composition Explorer (ACE has been used in the present study. GPS receivers located at Udaipur (Geog. Lat. 24.73° N, Geog. Long. 73.73° E and Hyderabad (Geog. Lat. 17.33° N, Geog. Long. 78.47° E have been used for wider spatial coverage in the Indian zone. Storm induced features in vertical TEC (VTEC have been obtained comparing them with the mean VTEC of quiet days. Variations in solar wind parameters, as obtained from ACE and in the SYM-H index, indicate that the storm commenced on 15 May 2005 at 02:39 UT. The main phase of the storm commenced at 06:00 UT on 15 May with a sudden southward turning of the Z-component of interplanetary magnetic field (IMF-Bz and subsequent decrease in SYM-H index. The dawn-to-dusk convection electric field of high latitude origin penetrated to low and equatorial latitudes simultaneously as corroborated by the magnetometer data from the Indian zone. Subsequent northward turning of the IMF-Bz, and the penetration of the dusk-to-dawn electric field over the dip equator is also discernible. Response of the low latitude ionosphere to this storm may be characterized in terms of (i

  11. October 29-31, 2003 geomagnetic storm: geomagnetically induced currents and their relation to problems in the Swedish high-voltage power transmission system

    Science.gov (United States)

    Pulkkinen, A. A.; Lindahl, S.; Viljanen, A.; Pirjola, R.

    2004-12-01

    In October 30, 2003, an ongoing geomagnetic superstorm knocked down a part of the high-voltage power transmission system in southern Sweden operated by the Sydkraft company. The blackout lasted for an hour and left about 50000 people without electricity. The incident was probably the most severe GIC failure observed since the well-known March 1989 Québec blackout and thus the problems in a Swedish system deserve a closer look. The geophysical background and the impacts on the Swedish high-voltage power transmission system of the October 29-31, 2003 geomagnetic storm are described in the study at hand. It was seen that athough no serious problems in North-America have been reported, the "three-phase" storm produced exceptionally large geomagnetic activity at the Fennoscandian auroral region. It was also seen that GIC modeled for southern Sweden region using very simplistic methods were able to explain the times of the failures in the Swedish system thus confirming the sources of experienced problems and adding also GIC to the long list of causes of technological impacts of the storm. Though the great diversity of the GIC drivers are addresses in the study, the problems in operating the Swedish system during the exceptionally intense storm of October 29-31, 2003 are attributed geophysically to substorms, SSCs and enhanced ionospheric convection all of which were creating large and complex geoelectric fields capable of driving large GIC. Based on the basic two-fold nature of the failure-related geoelectric field characteristics, a semi-deterministic approach for forecasting GIC-related geomagnetic activity in which average overall activity is supplemented with statistical estimations of the amplitudes of GIC fluctuations is suggested.

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

    Directory of Open Access Journals (Sweden)

    L. Svalgaard

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

  13. Long-term variations of geomagnetic activity and their solar sources

    CERN Document Server

    Kirov, B; Georgieva, K; Nepomnyashtaya, E V; Shelting, B D

    2013-01-01

    Geomagnetic activity in each phase of the solar cycle consists of 3 parts: (1) a floor below which the geomagnetic activity cannot fall even in the absence of sunspots, related to moderate graduate commencement storms; (2) sunspot-related activity due to sudden commencement storms caused by coronal mass ejections; (3) graduate commencement storms due to high speed solar wind from solar coronal holes. We find that the changes in the floor depend on the global magnetic moment of the Sun, and on the other side, from the height of the floor we can judge about the amplitude of the sunspot cycle.

  14. The Study of the Geomagnetic Variation for Sq current System

    Science.gov (United States)

    Zhao, X.; Du, A.

    2012-04-01

    The solar quiet variation (Sq) with a period of 24 hrs is a typical one of the quiet variations. Sq is generally caused by atmospheric tide-dynamo in ionosphere and it is controlled by the electric field, electric conductivity in ionosphere and neutral wind in middle-high altitude atmosphere. In our work, the geomagnetic field data observed by 90 ground-based observatories is used to analyze the local time variation of Sq. Sq is derived from five quiet-day geomagnetic data in every month by the FFT method. According to the pattern of geomagnetic X component in Sq, there is a prenoon-postnoon (before noon and after noon) asymmetry. This asymmetry is obvious in spring, summer and winter. The X component at 12:00-13:00 LT is about 5 nT larger than it at 11:00-12:00 LT. The ratio between the X component of daily variable amplitude and Y component of daily variable amplitude in middle and low (high) latitude regions in summer is greater (smaller) than that in winter. Used the sphere harmonic analysis method, the Sq equivalent current system is obtained. From the pattern of Sq current system, the prenoon-postnoon asymmetry may be caused by the electric field in the high latitude region. This electric field has two effects: the one is that the electric field from high latitude maps to the low latitude region; the other is this electric field penetrate to the middle latitude region directly. The combined action of these two effects makes the prenoon-postnoon asymmetry of Sq. The asymmetry also has an obvious seasonal effect. It may relate to the polar Sq and DP2 in the high latitude region.

  15. Correlation between fluxgate and SQUID magnetometer data sets for geomagnetic storms

    Directory of Open Access Journals (Sweden)

    Matladi Thabang

    2014-01-01

    Full Text Available There has always been a need to monitor the near Earth's magnetic field, as this monitoring provides understanding and possible predictions of Space Weather events such as geomagnetic storms. Conventional magnetometers such as fluxgates have been used for decades for Space Weather research. The use of highly sensitive magnetometers such as Superconducting QUantum Interference Devices (SQUIDs, promise to give more insight into Space Weather. SQUIDs are relatively recent types of magnetometers that exploit the superconductive effects of flux quantization and Josephson tunneling to measure magnetic flux. SQUIDs have a very broad bandwidth compared to most conventional magnetometers and can measure magnetic flux as low as a few femtotesla. Since SQUIDs have never been used in Space Weather research, unshielded, it is necessary to investigate if they can be reliable Space Weather instruments. The validation is performed by comparing the frequency content of the SQUID and fluxgate magnetometers, as reported by Phiri.

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

    Science.gov (United States)

    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.

  17. Correlation of geomagnetic anomalies recorded at Muntele Rosu Seismic Observatory (Romania with earthquake occurrence and solar magnetic storms

    Directory of Open Access Journals (Sweden)

    Adrian Septimiu Moldovan

    2012-04-01

    Full Text Available

    The study presents a statistical cross-correlation between geomagnetic anomalies, earthquake occurrence and solar magnetic storms. The working data are from: (i geomagnetic field records from Muntele Rosu (MLR Observatory, and from Surlari (SUA and/or Tihany (THY INTERMAGNET Observatories; (ii seismic data for the Vrancea source zone; and (iii daily geomagnetic indices from the NOAA/Space Weather Prediction Center. All of the geomagnetic datasets were recorded from 1996 to the present, at MLR, SUA or THY, and they were automatically corrected using a LabVIEW program developed especially for this purpose, highlighting the missing or bad data. Missing data blocks were completed with the last good measured value. After correction of the data, there were a number of issues seen regarding previous interpretations of the geomagnetic anomalies. Some geomagnetic anomalies identified as precursory signals were found to be induced either by increased solar activity or by malfunction of the data acquisition system, which produced inconsistent data, with numerous gaps. The MLR geomagnetic data are compared with the data recorded at SUA/THY and correlated with seismicity and solar activity. These 15 years of investigations cover more than a complete solar cycle, during which time the solar-terrestrial perturbations have fluctuated from very low to very high values, providing the ideal medium to investigate the correlations between the geomagnetic field perturbations, the earthquakes and the solar activity. The largest intermediate depth earthquake produced in this interval had a moment magnitude Mw 6.0 (2004 and provided the opportunity to investigate possible connections between local geomagnetic field behavior and local intermediate seismicity.

     

  18. Gravitational dynamos and the low-frequency geomagnetic secular variation

    Science.gov (United States)

    Olson, P.

    2007-01-01

    Self-sustaining numerical dynamos are used to infer the sources of low-frequency secular variation of the geomagnetic field. Gravitational dynamo models powered by compositional convection in an electrically conducting, rotating fluid shell exhibit several regimes of magnetic field behavior with an increasing Rayleigh number of the convection, including nearly steady dipoles, chaotic nonreversing dipoles, and chaotic reversing dipoles. The time average dipole strength and dipolarity of the magnetic field decrease, whereas the dipole variability, average dipole tilt angle, and frequency of polarity reversals increase with Rayleigh number. Chaotic gravitational dynamos have large-amplitude dipole secular variation with maximum power at frequencies corresponding to a few cycles per million years on Earth. Their external magnetic field structure, dipole statistics, low-frequency power spectra, and polarity reversal frequency are comparable to the geomagnetic field. The magnetic variability is driven by the Lorentz force and is characterized by an inverse correlation between dynamo magnetic and kinetic energy fluctuations. A constant energy dissipation theory accounts for this inverse energy correlation, which is shown to produce conditions favorable for dipole drift, polarity reversals, and excursions. PMID:18048345

  19. Cosmic rays during great geomagnetic storms in cycle 23 of solar activity

    Science.gov (United States)

    Kravtsova, M. V.; Sdobnov, V. E.

    2016-03-01

    Variations in the cosmic ray intensity (specifically, Forbush effects) and in the geomagnetic cutoff rigidity planetary system during powerful geomagnetic disturbances in cycle 23 were studied based on worldwide station network data by the global spectrographic survey method. The cosmic ray variation spectra during these periods and the spectral indices of these variations when the spectrum was approximated by the power function of the particle rigidity varying from 10 to 50 GV during different Forbush effect development phases are presented. It was indicated that the spectral indices of cosmic ray variations during spectrum approximation by the power function of the particle rigidity are larger during the maximal modulation phase than during the cosmic ray intensity decline and recovery phases. The fact that the amplitude of the second harmonic of the cosmic ray pitch angle anisotropy did not increase on November 20, 2003, confirms that the Earth fell into a Sun-independent spheromark magnetic cloud. The increased amplitudes of the second harmonic of the cosmic ray pitch angle anisotropy during other Forbush effects in July 2000, March-April 2001, October 2003, and November 2004 indicate that the Earth was in the coronal mass ejection region, in which the interplanetary magnetic field structure was loop-like during these periods.

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

    Science.gov (United States)

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

    2016-07-01

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

  1. Response of the Ionospheric F-region in the Latin American Sector During the Intense Geomagnetic Storm of 21-22 January 2005

    Science.gov (United States)

    Sahai, Y.; Fagundes, P. R.; de Jesus, R.; de Abreu, A. J.; Crowley, G.; Pillat, V. G.; Guarnieri, F. L.; Abalde, J. R.; Bittencourt, J. A.

    2009-12-01

    Ionospheric storms are closely associated with geomagnetic storms and are an extreme example of space weather events. The response of the ionosphere to storms is rather complicated. In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21-22 January 2005 (with storm sudden commencement (SSC) at 1712 UT on 21 January). This geomagnetic storm is anomalous (minimum Dst reached -105 nT at 0700 UT on 22 January) because the main phase occurred during the northward excursion of the Bz component of interplanetary magnetic fields (IMFs). The monthly mean F10.7 solar flux for the month of January 2005 was 99.0 sfu. The ionospheric F-region parameters observed at Ramey (18.5 N, 67.1 W; RAM), Puerto Rico, Jicamarca (12.0 S, 76.8 W; JIC), Peru, Manaus (2.9 S, 60.0 W; MAN), and São José dos Campos (23.2 S, 45.9 W; SJC), Brazil, during 21-22 January (geomagnetically disturbed) and 25 January (geomagnetically quiet) have been analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid uplifting of the F-region peak heights(hpF2/hmF2) and a decrease in the NmF2 coincident with the time of SSC. At both RAM and SJC an uplifting of the F-region peak height is observed at about 2000 UT. The low-latitude station SJC shows a coincident decrease in NmF2 with the uplifting, whereas the mid-latitude station RAM shows a decrease in NmF2 earlier than the uplifting. Also, the observed variations in the F-region ionospheric parameters are compared with the TIMEGCM model run for 21-22 January and the model results show both similarities and differences from the observed results. Average GPS-TEC (21-22 and 25 January) and phase fluctuations (21, 22, 25, 26 January) observed at Belem (1.5 S, 48.5 W; BELE), Brasilia (15.9 S, 47.9 W; BRAZ), Presidente Prudente (22.3o S, 51.4 W; UEPP), and Porto Alegre (30.1 S, 51.1 W; POAL), Brazil, are also presented. These GPS stations belong to

  2. Changes in cosmic ray cut-off rigidities due to secular variations of the geomagnetic field

    Directory of Open Access Journals (Sweden)

    A. Bhattacharyya

    Full Text Available An analytical expression is derived for the cutoff rigidity of cosmic rays arriving at a point in an arbitrary direction, when the main geomagnetic field is approximated by that of an eccentric dipole. This expression is used to determine changes in geomagnetic cutoffs due to secular variation of the geomagnetic field since 1835. Effects of westward drift of the quadrupole field and decrease in the effective dipole moment are seen in the isorigidity contours. On account of the immense computer time required to determine the cutoff rigidities more accurately using the particle trajectory tracing technique, the present formulation may be useful in estimating the transmission factor of the geomagnetic field in cosmic ray studies, modulation of cosmogenic isotope production by geomagnetic secular variation, and the contribution of geomagnetic field variation to long term changes in climate through cosmic ray related modulation of the current flow in the global electric circuit.

  3. F-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987

    Directory of Open Access Journals (Sweden)

    S. Kawamura

    2004-11-01

    Full Text Available We have presented a comparison between the modeled NmF2 and hmF2, and NmF2 and hmF2 which were observed at the equatorial anomaly crest and close to the geomagnetic equator simultaneously by the Akita, Kokubunji, Yamagawa, Okinawa, Manila, Vanimo, and Darwin ionospheric sounders and by the middle and upper atmosphere (MU radar (34.85° N, 136.10° E during the 25-27 August 1987 geomagnetically storm-time period at low solar activity near 201°, geomagnetic longitude. A comparison between the electron and ion temperatures measured by the MU radar and those produced by the model of the ionosphere and plasmasphere is presented. The corrections of the storm-time zonal electric field, EΛ, from 16:30 UT to 21:00 UT on 25 August bring the modeled and measured hmF2 into reasonable agreement. In both hemispheres, the meridional neutral wind, W, taken from the HWW90 wind model and the NRLMSISE-00 neutral temperature, Tn, and densities are corrected so that the model results agree with the ionospheric sounders and MU radar observations. The geomagnetic latitude variations in NmF2 on 26 August differ significantly from those on 25 and 27 August. The equatorial plasma fountain undergoes significant inhibition on 26 August. This suppression of the equatorial anomaly on 26 August is not due to a reduction in the meridional component of the plasma drift perpendicular to the geomagnetic field direction, but is due to the action of storm-time changes in neutral winds and densities on the plasma fountain process. The asymmetry in W determines most of the north-south asymmetry in hmF2 and NmF2 on 25 and 27 August between about 01:00-01:30 UT and about 14:00 UT when the equatorial anomaly exists in the ionosphere, while asymmetries in W, Tn, and neutral densities relative to the geomagnetic equator are responsible for the north-south asymmetry in NmF2 and hmF2 on 26 August. A theory of the primary mechanisms causing the morning and evening peaks in the electron

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

    Science.gov (United States)

    Panovska, Sanja; Constable, Catherine

    2015-04-01

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

  5. Variations of the Magnetosphere Resonance Frequencies During Magnetic Storm of July 15——16, 2000

    Institute of Scientific and Technical Information of China (English)

    A. Potapov; A. Polyakov; T. Polyushkina; H. Zhao

    2005-01-01

    ULF observations at two mid-latitude sites during the large geomagnetic storm of July 15-16,2000 were used to trace variations of resonance frequencies of the field line resonators. A brief description of the geomagnetic disturbance as it was observed on the ground, at the geostationary orbit, and before the Earth's bow shock is given. Then a detailed study of ULF dynamic spectra from Borok and Mondy is performed for8 succesive 6-hour intervals of July 15 and 16. In conclusion some tasks for the future work are listed.

  6. Behavior of the ionosphere over Europe during two geomagnetic storms which caused tongues of ionization over North America.

    Science.gov (United States)

    Rodriguez-Bouza, Marta; Herraiz, Miguel; Rodriguez-Caderot, Gracia; Radicella, Sandro M.

    2015-04-01

    This work presents the effect of two geomagnetic storms on the ionospheric total electron content (TEC) over Europe. Those geomagnetic storms occurred on July 14th, 2013 and February 19th, 2014 and originated a tongue of ionization over North America. Following the criteria of Gonzalez et al.(1994), the July storm can be classified as a moderate one because the Dst index reached a value of -72nT, whereas the February storm as an intense event considering that Dst index dropped to -112nT. For this study we have used RINEX files obtained from GNSS stations belonging to International GPS Service, IGS, EUREF Permanent Network, and University Navstar Consortium, UNAVCO, networks. The data has been divided into two groups in function of the region: Europe or North America. For each group we have used all the available stations. The RINEX files have been processed using a technique developed by Ciraolo (2012) which assumes the ionospheric thin shell model to obtain the vertical total electron content (vTEC) from the slant total electron content (sTEC) at the Ionospheric Pierce Point, IPP, the point where the line-of-sight between the satellite and the ground receiver intersects the ionosphere. The data were obtained at 1 minute sampling in periods of geomagnetic storms and quiet days close to them. In both storms a tongue of ionization, ToI, appeared over North America from afternoon to dusk (between 19:00 and 3:00 GMT). The behavior of the ionosphere over Europe was very different in eachcase. In July, the TEC decreased respect the quiet days during the ToI time. In the February storm the behavior of the ionosphere over Europe was similar to that of a quiet day but the following day appeared a phenomenom similar to the ToI. Ciraolo, L. (2012). Ionospheric Total Electron Content (TEC) from Global Positioning System. Personal Communication. González, W.D., Joselyn, J. A., Kamide, Y., Kroehl, H. W., Rostoker, G., Tsurutani, B. T., Vasyliunas, V. M. (1994). What is a

  7. Mapping geomagnetic secular variation at the core-mantle boundary

    DEFF Research Database (Denmark)

    Holme, R.; Olsen, Nils; Bairstow, F. L.

    2011-01-01

    , the coherence of the maps up to harmonic degree 13 suggests that it is possible to obtain useful insight from their examination. Low SV is confirmed under the Pacific, but also revealed under the North Atlantic and Antarctica. These features are more readily explained in terms of dynamo control through thermal......-fit by functions proportional to l(l + 1) where l is the spherical harmonic degree. The ratio of the two spectra defines a timescale for geomagnetic variations of approximately 10 yrs for all resolvable harmonic degrees. The blue spectra should prevent meaningful maps of the SV being generated; nevertheless...... core–mantle coupling than by electromagnetic screening. Comparison with maps from measurements prior to the recent satellites, using the ‘Comprehensive Model’, suggests that models back to at least 1970 are sufficiently good to enable direct comparison of the SV....

  8. Hydro-Quebec and geomagnetic storms: measurement techniques, effects on transmission network and preventive actions since 1989.

    Science.gov (United States)

    Beland, J.

    In March 1989 the province of Quebec in Canada suffered an almost complete blackout during a severe geomagnetic storm. Millions of Hydro-Québec's customers have been left without electricity for several hours. Fifteen years later, many changes have been implemented to avoid the repetition of such an event. Among them, we now have two measurement systems (one primary and one backup) monitoring ground induced current (GIC) effects on the grid in real time. Those systems are described and examples of data acquired during major storms (as in late October 2003) are given. To be informed in advance of a probable GIC occurrence, HQ now relies on a specialized organization providing geomagnetic activity alert and forecast. Following an alert or the detection of GIC effects on the network exceeding a minimal threshold, special operation rules become in effect with the objective of ensuring maximum stability and safety margin. Another major improvement is the introduction of series capacitors on several 735 kV lines, which increases network stability and also block GIC circulation. In conclusion, HQ now believes that its network can survive to any realistic geomagnetic storm.

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

    Science.gov (United States)

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

    2016-06-01

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

  10. GPS phase scintillation at high latitudes during the geomagnetic storm of 17-18 March 2015

    Science.gov (United States)

    Prikryl, P.; Ghoddousi-Fard, R.; Weygand, J. M.; Viljanen, A.; Connors, M.; Danskin, D. W.; Jayachandran, P. T.; Jacobsen, K. S.; Andalsvik, Y. L.; Thomas, E. G.; Ruohoniemi, J. M.; Durgonics, T.; Oksavik, K.; Zhang, Y.; Spanswick, E.; Aquino, M.; Sreeja, V.

    2016-10-01

    The geomagnetic storm of 17-18 March 2015 was caused by the impacts of a coronal mass ejection and a high-speed plasma stream from a coronal hole. The high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including GPS receivers, HF radars, ionosondes, riometers, and magnetometers. The phase scintillation index is computed for signals sampled at a rate of up to 100 Hz by specialized GPS scintillation receivers supplemented by the phase scintillation proxy index obtained from geodetic-quality GPS data sampled at 1 Hz. In the context of solar wind coupling to the magnetosphere-ionosphere system, it is shown that GPS phase scintillation is primarily enhanced in the cusp, the tongue of ionization that is broken into patches drawn into the polar cap from the dayside storm-enhanced plasma density, and in the auroral oval. In this paper we examine the relation between the scintillation and auroral electrojet currents observed by arrays of ground-based magnetometers as well as energetic particle precipitation observed by the DMSP satellites. Equivalent ionospheric currents are obtained from ground magnetometer data using the spherical elementary currents systems technique that has been applied over the ground magnetometer networks in North America and North Europe. The GPS phase scintillation is mapped to the poleward side of strong westward electrojet and to the edge of the eastward electrojet region. Also, the scintillation was generally collocated with fluxes of energetic electron precipitation observed by DMSP satellites with the exception of a period of pulsating aurora when only very weak currents were observed.

  11. St. Patrick's Day 2015 geomagnetic storm analysis based on Real Time Ionosphere Monitoring

    Science.gov (United States)

    García-Rigo, Alberto

    2017-04-01

    Ionosphere Monitoring (RTIM) is a new Working Group within the International Association of Geodesy (IAG) Sub-Commission 4.3 "Atmosphere Remote Sensing". The complementary expertise of the participating research groups allows to analyse the ionospheric behaviour from a broad perspective, taking benefit of comparing multiple independent real time and near real time ionospheric approaches. In this context, a detailed analysis will be presented for the days in March, 2015 surrounding St. Patrick's Day 2015 geomagnetic storm, based on the existing ionospheric models (global or regional) within the group, which are mainly based on Global Navigation Satellite Systems (GNSS) and ionosonde data. For this purpose, a variety of ionospheric parameters will be considered, including Total Electron Content (TEC), F2 layer critical frequency (foF2), F2 layer peak (hmF2), bottomside half-thickness (B0) and ionospheric disturbance W-index. Also, ionospheric high-frequency perturbations such as Travelling Ionospheric Disturbances (TIDs), scintillations and the impact of solar flares facing the Earth will be presented to derive a clear picture of the ionospheric dynamics. Among other sources of information to take part in the comparisons, there will be (1) scintillation results -from MONITOR ESA/ESTEC-funded project- derived by means of S4 index and Sigma Phi (IEEA), specially significant in the African sector and European high latitudes, (2) dynamics of the global maps of W-index with 1h resolution derived from JPL Global Ionospheric Maps (GIMs; IZMIRAN), (3) deviations from expected quiet-time behavior analysed in terms of foF2, hmF2, B0 and B1 based on IRTAM and GIRO network of digisondes (Lowell), showing F2 layer peculiar changes due to the storm, (4) statistics based on the median of the VTEC for the 15 previous days considering VTEC european regional maps (ROB), (5) time series of VTEC data that are derived by running the NRT ionosphere model of DGFI-TUM in offline mode, which show

  12. Prediction of geomagnetic storms from solar wind data with the use of a neural network

    Directory of Open Access Journals (Sweden)

    H. Lundstedt

    Full Text Available An artificial feed-forward neural network with one hidden layer and error back-propagation learning is used to predict the geomagnetic activity index (Dst one hour in advance. The Bz-component and ΣBz, the density, and the velocity of the solar wind are used as input to the network. The network is trained on data covering a total of 8700 h, extracted from the 25-year period from 1963 to 1987, taken from the NSSDC data base. The performance of the network is examined with test data, not included in the training set, which covers 386 h and includes four different storms. Whilst the network predicts the initial and main phase well, the recovery phase is not modelled correctly, implying that a single hidden layer error back-propagation network is not enough, if the measured Dst is not available instantaneously. The performance of the network is independent of whether the raw parameters are used, or the electric field and square root of the dynamical pressure.

  13. Solar wind - magnetosphere coupling efficiency during ejecta and sheath region driven geomagnetic storms

    Science.gov (United States)

    Myllys, Minna; Kilpua, Emilia; Lavraud, Benoit

    2016-04-01

    We have investigated the effect of key solar wind driving parameters on solar wind- magnetosphere coupling efficiency during sheath and magnetic cloud driven storms. The particular focus of the study was on the coupling efficiency dependence with Alfven Mach number (MA). The efficiency has been estimated using the dawn-dusk component of the interplanetary electric field (EY), Newell and Borovsky functions as a proxy for the energy inflow and the polar cap potential (PCN), auroral electrojet (AE) and SYM-H indices as the measure of the energy output. We have also performed a time delay analysis between the input parameters and the geomagnetic indices. We demonstrate that the PCN index distinctively shows both a MA dependent saturation and a MA-independent saturation, pointing to the existence of at least two underlying physical mechanisms for the saturation of the index. By contrast, we show that the AE index saturates, but that the saturation of this index is independent of the solar wind MA. Finally we find that the SYM-H index does not seem to saturate and that the absence of saturation is independent of the MA regime.

  14. The interplanetary origins and the main-phase development of moderate geomagnetic storms (1978 - 1979). Ph. D. Thesis

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, O. Jr.

    1992-08-01

    Geomagnetic storms are related to the ring current, which is driven by energy injection primarily during energetic solar wind-magnetosphere coupling due to reconnection at the magnetopause. This work identified the interplanetary origins of moderate geomagnetic storms (-100 nT less than or equal to Dst(MIN) less than -50 nT) and analyzed the coupling processes during the storm main phase. For this purpose the interplanetary magnetic field, solar-wind temperature, density and velocity data, obtained by the ISEE-3 satellite, were used together with the equatorial-Dst and auroral-AE geomagnetic indices, provided by the World Data Center, for the interval August/1978 - December/1979. 78 moderate storms were identified, in which 40 storm events (Dst beginning at approximately 0 nT) were selected. Related to these well defined events the following interplanetary origins were found: coronal mass ejections phenomena - CME (40 percent related to interplanetary shocks; 22.5 percent to single streams; 17.5 percent to streams interactions; 10 percent to non-compressive density enhancement) and non-CME phenomena (7.5 percent related to Alfven-like waves and 2.5 percent to no-identified feature). 47 percent of CME-phenomena occurred near the heliospheric current sheet. Regarding the main-phase development all energy coupling functions showed a similar behavior, that is, the south component of the interplanetary magnetic field (in the magnetospheric coordinate frame) controls basically this coupling. The best linear fits were given by Ey electric field-like and epsilon electric power-like functions. However the complexities in these coupling relations point to other simultaneous energy transfer processes such as non-proportional transference, viscous transference, and unloading' process.

  15. Cosmic Ray Monitoring and Space Dangerous Phenomena, 2. Methods of Cosmic Ray Using For Forecasting of Major Geomagnetic Storms

    Science.gov (United States)

    Belov, A. V.; Dorman, L. I.; Eroshenko, E. A.; Iucci, N.; Mavromichalaki, H.; Pustil'Nik, L. A.; Sternlieb, A.; Villoresi, G.; Yanke, V. G.; Zukerman, I. G.

    We present developing of methods (e.g., Dorman et al., 1995, 1999) for forecasting on the basis of neutron monitor hourly on-line data (as well as on-line muon tele- scopes hourly data from different directions) geomagnetic storms of scales G5 (3- hour index of geomagnetic activity Kp=9), G4 (Kp=8) and G3 (Kp=7) (according to NOAA Space Weather Scales). These geomagnetic storms are dangerous for peo- ple technology and health (influence on power systems, on spacecraft operations, on HF radio-communications and others). We show that for especially dangerous geo- magnetic storms can be used global-spectrographic method if on-line will be avail- able 35-40 NM and muon telescopes. In this case for each hour can be determined CR anisotropy vector, and the specifically behavior of this vector before SC of ge- omagnetic storms G5, G4 or G3 (according to NOAA Space Weather Scales) can be used as important factor for forecast. The second factor what can be used for SC forecast is specifically behavior of CR density (CR intensity) for about 30-15 hours before SC (caused mainly by galactic CR particles acceleration during interaction with shock wave moved from the Sun). The third factor is effect of cosmic ray pre- decreasing, caused by magnetic connection of the Earth with the region behind the shock wave. We demonstrate developing methods on several examples of major ge- omagnetic storms. REFERENCES: Dorman L.I., et al. "Cosmic-ray forecasting fea- tures for big Forbush-decreases". Nuclear Physics B, Vol. 49A, pp. 136-144. (1995). L.I.Dorman, et al, "Cosmic ray Forbush-decrease as indicators of space dangerous phenomenon and possible use of cosmic ray data for their prediction", Proc. of 26-th Intern. Cosmic Ray Conference, Salt Lake City, Vol. 6, p. 476-479, (1999).

  16. Midlatitude ionospheric changes to four great geomagnetic storms of solar cycle 23 in Southern and Northern Hemispheres

    Science.gov (United States)

    Merline Matamba, Tshimangadzo; Habarulema, John Bosco; Burešová, Dalia

    2016-12-01

    This paper presents an investigation of ionospheric response to great (Dst ≤-350 nT) geomagnetic storms that occurred during solar cycle 23. The storm periods analyzed are 29 March to 2 April 2001, 27-31 October 2003, 18-23 November 2003, and 6-11 November 2004. Global Navigation Satellite System, total electron content (TEC), and ionosonde critical frequency of F2 layer (foF2) data over Southern Hemisphere (African sector) and Northern Hemisphere (European sector) midlatitudes were used to study the ionospheric responses within 15°E-40°E longitude and ±31° to ±46° geomagnetic latitude. Midlatitude regions within the same longitude sector in both hemispheres were selected in order to assess the contribution of the low-latitude changes especially the expansion of equatorial ionization anomaly (EIA) also called the dayside ionospheric superfountain effect during these storms. In all storm periods, both negative and positive ionospheric responses were observed in both hemispheres. Negative ionospheric responses were mainly due to changes in neutral composition, while the expansion of the EIA led to pronounced positive storm effects at midlatitudes for some storm periods. In other cases (e.g., 29 October 2003), penetration electric fields, EIA expansion, and large-scale traveling ionospheric disturbances were found to be present during the positive storm effect at midlatitudes in both hemispheres. An increase in TEC on the 28 October 2003 was because of the large solar flare with previously determined intensity of X45 ±5.

  17. GEOMAGNETIC STORMS AND CARRINGTON EVENT = TEMPESTADES GEOMAGNETICAS E O EVENTO CARRINGTON

    Directory of Open Access Journals (Sweden)

    Gerson Antonio Santarine

    2014-06-01

    Full Text Available Disasters may be understood as a result of adverse events that produce impacts on society. The scientific development, as well as deepen the understanding of ancient natural phenomena, opened new prospects for discovered several other, as yet unknown, revealing potentially dangerous situations for the environment that, until then, remained unsuspected. In this class of extremes events lie the geomagnetic storms. This is caused by the massive storms coronal mass ejections from the Sun to reach Earth's magnetosphere. If Earth is directly in line sight of a coronal blast, a shock wave of energetic charged particles from the star will cause a geomagnetic storm due to its abrupt interaction with terrestrial magnetic field. Satellites in space will be the first artifacts seriously affected by energy transient due a high probability of firing onboard electronics components, causing breakdowns in communication systems. Also may have its orbits altered by aerodynamic drag caused by increase of atmosphere thickness after heating the upper layers, as result of electromagnetic pulse absorption from solar flare. On surface depending on the storm magnitude, magnetic fluctuations with consequent induction of overhead power transmission cables will cause burning on transformers in generalized short circuits. On nineteenth century Earth has been hit by a tremendous (more intense reaching Earth that has historical record coronal ejection which was known as Carrington event , occurred in 1859, with reports innumerable injury on northern hemisphere. This article analyzes, succinctly, geomagnetic storms and some possible consequences for modern technological society case similar to Carrington event will occur today. = Catástrofes podem ser entendidas como o resultado de eventos adversos que causam impactos na Sociedade. O desenvolvimento científico, além de aprofundar o entendimento de antigos fenômenos naturais, abriu novas perspectivas para descobertas de

  18. Cosmic Ray Monitoring and Space Dangerous Phenomena, 1. Search of Features In Cosmic Rays What Can Be Used For Forecasting of Major Geomagnetic Storms

    Science.gov (United States)

    Dorman, L. I.; Pustil'Nik, L. A.; Sternlieb, A.; Zukerman, I. G.

    According to NOAA Space Weather Scales, geomagnetic storms of scales G5 (3- hour index of geomagnetic activity Kp=9), G4 (Kp=8) and G3 (Kp=7) are dangerous for people technology and health (influence on power systems, on spacecraft oper- ations, on HF radio-communications and others). To prevent these serious damages will be very important to forecast dangerous geomagnetic storms. In many papers it was shown that in principle for this forecasting can be used data on CR intensity and CR anisotropy changing before SC of major geomagnetic storms accompanied by sufficient Forbush-decreases (e.g., Dorman et al., 1995, 1999). In this paper we con- sider over 100 major geomagnetic storms and for each case we analyze hourly data of many NM for 8 days with SC in the 4-st day of 8-days period (that before SC we have at least 3 full days). We determine what part of major geomagnetic storms is accompanied CR intensity and CR anisotropy changing before SC, and what part of major geomagnetic storms does not show any features what can be used for forecast- ing. We estimate also how these parts depend from the index of geomagnetic activ- ity Kp. REFERENCES: Dorman L.I., et al. "Cosmic-ray forecasting features for big Forbush-decreases". Nuclear Physics B, Vol. 49A, pp. 136-144. (1995). L.I.Dorman, et al, "Cosmic ray Forbush-decrease as indicators of space dangerous phenomenon and possible use of cosmic ray data for their prediction", Proc. of 26-th Intern. Cos- mic Ray Conference, Salt Lake City, Vol. 6, p. 476-479, (1999).

  19. Satellite and Ground-Based Observations of Auroral Energy Deposition and the Effects on Thermospheric Composition During Large Geomagnetic Storms: 1. Great Geomagnetic Storm of 20 November 2003

    Science.gov (United States)

    2008-01-01

    studies during both distribution of low-energy electrons well below 1 keV that are geomagnetically quiet and disturbed periods [e.g., see Nier the suspected...4510. energies inferred from the Sondre Stromtjord radar, J. Geophys. Res., 96, Nier , A. 0., W. E. Potter, and D. C. Kayser (1976), Atomic and

  20. The 1995 revision of the joint US/UK geomagnetic field models - I. Secular variation

    Science.gov (United States)

    Macmillan, S.; Barraclough, D.R.; Quinn, J.M.; Coleman, R.J.

    1997-01-01

    We present the methods used to derive mathematical models of global secular variation of the main geomagnetic field for the period 1985 to 2000. These secular-variation models are used in the construction of the candidate US/UK models for the Definitive Geomagnetic Reference Field at 1990, the International Geomagnetic Reference Field for 1995 to 2000, and the World Magnetic Model for 1995 to 2000 (see paper II, Quinn et al., 1997). The main sources of data for the secular-variation models are geomagnetic observatories and repeat stations. Over the areas devoid of these data secular-variation information is extracted from aeromagnetic and satellite data. We describe how secular variation is predicted up to the year 2000 at the observatories and repeat stations, how the aeromagnetic and satellite data are used, and how all the data are combined to produce the required models.

  1. Effects of ULF wave power on relativistic radiation belt electrons: 8-9 October 2012 geomagnetic storm

    Science.gov (United States)

    Pokhotelov, D.; Rae, I. J.; Murphy, K. R.; Mann, I. R.

    2016-12-01

    Electromagnetic ultralow-frequency (ULF) waves are known to play a substantial role in radial transport, acceleration, and loss of relativistic particles trapped in the Earth's outer radiation belt. Using in situ observations by multiple spacecraft operating in the vicinity of outer radiation belts, we analyze the temporal and spatial behavior of ULF waves throughout the geomagnetic storm of 8-9 October 2012 and compare with the dynamics of relativistic electron fluxes on board the twin Van Allen Probes spacecraft. The analysis shows that the relativistic electron fluxes reduce from their prestorm levels during the first phase of the storm and rapidly increase during the second phase of the storm. We demonstrate that the behavior of ULF wave power changes throughout the storm, from ULF oscillations being a mixture of compressional and shear magnetic components during the first phase of the storm to ULF oscillations being dominated by transverse (shear) components during the second phase. We analyze the parameters of ULF-driven radial diffusion throughout the storm and compare the observed diffusion coefficients with their statistical averages. We demonstrate that the observed diffusion coefficients are strong enough to impact the redistribution of relativistic electron fluxes from and to the outer boundary of radiation belts and the diffusion might influence the effects of any local electron acceleration by transporting fluxes inward or outward according to phase space density gradients.

  2. Variations of angular elements of the geomagnetic field in Europe during the last 24 centuries

    Science.gov (United States)

    Burakov, K. S.; Nachasova, I. E.

    2011-05-01

    The analysis of variations in angular elements of the geomagnetic field during the period since 350 B.C. to the present day according to the findings from the study of thermal magnetization of baked archaeological samples from England, France, and East Europe showed that the key feature in the behavior of the geomagnetic inclination in all three regions is a millennial variation. The trend in the behavior of the inclination of the geomagnetic field can be regarded as a manifestation of a variation with a characteristic time scale of several thousand years. Despite the general likeness of variations in inclination and declination of the ancient geomagnetic field, they also exhibit a noticeable dissimilarity. The paths of the virtual geomagnetic pole reconstructed from the variations of angular elements of the geomagnetic field in East Europe indicate that the geomagnetic polar motion is quasi-cyclic. The duration of the first cycle was about 1000 years, while the second cycle has not been completed due to the change of the motion to the opposite direction in the middle of the XVII century.

  3. Response of the Ionospheric F2-region Over Irkutsk and Hainan to Strong Geomagnetic Storms

    Institute of Scientific and Technical Information of China (English)

    E B Romanova; G A Zherebtsov; K G Ratovsky; N M Polekh; J K Shi; X Wang; G J Wang

    2013-01-01

    The ionospheric responses to two strong storms on 17-19 August 2003 and 22-23 January 2004 are studied,using the data from Irkutsk (52.5°N,104°E) and Hainan (19.5°N,109°E)ionospheric stations.The analysis of variations in relative deviations of the critical frequency Af0F2 revealed that at middle latitudes (Irkutsk) negative disturbances were observed in the summer ionosphere; positive and negative ones,in the winter ionosphere during the main and recovery phases respectively.At low latitudes (Hainan),the disturbances were positive in all the cases considered.Mechanisms of the disturbances were analyzed with the aid of empirical models of the neutral atmosphere NRLMSISE-00 and thermospheric wind HWM07.The main factors determining Δf0F2 variations at middle latitudes during the storms were demonstrated to be the disturbed equatorward thermospheric wind transporting the disturbed atmospheric composition,the increase in the atomic oxygen concentration,and the passage of internal gravity waves.At low latitudes,the effects associated with neutral composition variations are less significant than those of the thermospheric wind and electric fields.

  4. Moderate geomagnetic storms of January 22-25, 2012 and their influences on the wave components in ionosphere and upper stratosphere-mesosphere regions

    Science.gov (United States)

    Mengistu Tsidu, Gizaw; Abraha, Gebregiorgis

    2014-11-01

    Moderate geomagnetic storms occurred during January 22-25, 2012 period. The geomagnetic storms are characterized by different indices and parameters. The SYM-H value on January 22 increased abruptly to 67 nT at sudden storm commencement (SSC), followed by a sharp decrease to -87 nT. A second SSC on January 24 followed by a shock on January 25 was also observed. These SSCs before the main storms and the short recovery periods imply the geomagnetic storms are CME-driven. The sudden jump of solar wind dynamic pressure and IMF Bz are also consistent with occurrence of CMEs. This is also reflected in the change in total electron content (TEC) during the storm relative to quiet days globally. The response of the ionospheric to geomagnetic storms can also be detected from wave components that account for the majority of TEC variance during the period. The dominant coherent modes of TEC variability are diurnal and semidiurnal signals which account upto 83% and 30% of the total TEC variance over fairly exclusive ionospheric regions respectively. Comparison of TEC anomalies attributed to diurnal (DW1) and semidiurnal (SW2) tides, as well as stationary planetary waves (SPW1) at 12 UTC shows enhancement in the positive anomalies following the storm. Moreover, the impact of the geomagnetic storms are distinctly marked in the daily time series of amplitudes of DW1, SW2 and SPW1. The abrupt changes in amplitudes of DW1 (5 TECU) and SW2 (2 TECU) are observed within 20°S-20°N latitude band and along 20°N respectively while that of SPW1 is about 3 TECU. Coherent oscillation with a period of 2.4 days between interplanetary magnetic field and TEC was detected during the storm. This oscillation is also detected in the amplitudes of DW1 over EIA regions in both hemispheres. Eventhough upward coupling of quasi two day wave (QTDWs) of the same periodicity, known to have caused such oscillation, are detected in both ionosphere and upper stratosphere, this one can likely be attributed to

  5. Solar wind-magnetosphere coupling efficiency during ejecta and sheath-driven geomagnetic storms

    Science.gov (United States)

    Myllys, M.; Kilpua, E. K. J.; Lavraud, B.; Pulkkinen, T. I.

    2016-05-01

    We have investigated the effect of key solar wind driving parameters on solar wind-magnetosphere coupling efficiency during sheath and magnetic cloud-driven storms. The particular focus of the study was on the coupling efficiency dependence with Alfvén Mach number (MA). The efficiency has been estimated using the dawn-dusk component of the interplanetary electric field (EY), Newell and Borovsky functions as a proxy for the energy inflow and the polar cap potential (PCN), and auroral electrojet (AE) and SYM-H indices as the measure of the energy output. We have also performed a time delay analysis between the input parameters and the geomagnetic indices. The optimal time lag and smoothing window length depend on the coupling function used and on the solar wind driver. For example, turbulent sheaths are more sensitive to the time shift and the averaging interval than smoother magnetic clouds. The results presented in this study show that the solar wind-magnetosphere coupling efficiency depends strongly on the definition used, and it increases with increasing MA. We demonstrate that the PCN index distinctively shows both a Mach number dependent saturation and a Mach number independent saturation, pointing to the existence of at least two underlying physical mechanisms for the saturation of the index. By contrast, we show that the AE index saturates but that the saturation of this index is independent of the solar wind Mach number. Finally, we find that the SYM-H index does not seem to saturate and that the absence of saturation is independent of the Mach number regime. We highlight the difference between the typical MA conditions during sheath regions and magnetic clouds. The lowest MA values are related to the magnetic clouds. As a consequence, sheaths typically have higher solar wind-magnetosphere coupling efficiencies than magnetic clouds.

  6. Modeling Multiple Plasma Populations During the June 23, 2015 Geomagnetic Storm

    Science.gov (United States)

    Moore, T. E.; DiStefano, N.; Garcia-Sage, K.; Giles, B. L.; Zhang, B.; Pembroke, A. D.

    2016-12-01

    On June 23, 2015 a large geomagnetic storm resulted in the spectacular views of the aurora from places as far southward as West Virginia. The Magnetospheric Multiscale (MMS), which was in its commissioning phase, captured the event on the night-side and dusk-side of Earth in the magnetosphere. Between 3 and 5 UT, MMS data demonstrated periods of ionospheric outflow of low-energy electrons and monoenergetic ions. Notably, during these periods of ionospheric outflow, the pitch angle of the electrons with respect to the magnetic field was predominantly zero degrees, meaning that these particles were mostly moving away from the Earth along open magnetic field lines. In order to test our understanding and ability to accurately model the event, we use the Lyon-Fedder-Mobarry (LFM) model, which is a global magnetohydrodynamic (MHD) model. We show single and multi-fluid simulations of the event in order to demonstrate the effects of ionospheric-origin plasma on the dynamics that MMS observes. Since the addition of ionospheric outflow to the LFM model can only incorporate thermal particles, we created a separate simulation of non-thermal particle trajectories due to Lorentz and gravitational forces based on LFM model data. In this simulation, we find that the outflowing H+, O+, and low-energy electrons observed by MMS come from the pre-midnight auroral region. We also find that the ions and low-energy electrons appear to undergo only minimal acceleration between 2.3 Earth radii and the location of MMS.

  7. Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

    Directory of Open Access Journals (Sweden)

    Y. Sahai

    2011-05-01

    Full Text Available In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21–22 January 2005. This geomagnetic storm has been considered "anomalous" (minimum Dst reached −105 nT at 07:00 UT on 22 January because the main storm phase occurred during the northward excursion of the Bz component of interplanetary magnetic fields (IMFs. The monthly mean F10.7 solar flux for the month of January 2005 was 99.0 sfu. The F-region parameters observed by ionosondes at Ramey (RAM; 18.5° N, 67.1° W, Puerto Rico, Jicamarca (JIC; 12.0° S, 76.8° W, Peru, Manaus (MAN; 2.9° S, 60.0° W, and São José dos Campos (SJC; 23.2° S, 45.9° W, Brazil, during 21–22 January (geomagnetically disturbed and 25 January (geomagnetically quiet have been analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid uplifting of the F-region peak heights (hpF2/hmF2 and a decrease in the NmF2 coincident with the time of storm sudden commencement (SSC. The observed variations in the F-region ionospheric parameters are compared with the TIMEGCM model run for 21–22 January and the model results show both similarities and differences from the observed results. Average GPS-TEC (21, 22 and 25 January and phase fluctuations (21, 22, 25, 26 January observed at Belem (BELE; 1.5° S, 48.5° W, Brasilia (BRAZ; 15.9° S, 47.9° W, Presidente Prudente (UEPP; 22.3° S, 51.4° W, and Porto Alegre (POAL; 30.1° S, 51.1° W, Brazil, are also presented. These GPS stations belong to the RBMC/IBGE network of Brazil. A few hours after the onset of the storm, large enhancements in the VTEC and NmF2 between about 20:00 and 24:00 UT on 21 January were observed at all the stations. However, the increase in VTEC was greatest at the near equatorial station (BELE and enhancements in VTEC decreased with latitude. It should be pointed out that no phase fluctuations or spread-F were observed in the Latin

  8. Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21-22 January 2005

    Science.gov (United States)

    Sahai, Y.; Fagundes, P. R.; de Jesus, R.; de Abreu, A. J.; Crowley, G.; Kikuchi, T.; Huang, C.-S.; Pillat, V. G.; Guarnieri, F. L.; Abalde, J. R.; Bittencourt, J. A.

    2011-05-01

    In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21-22 January 2005. This geomagnetic storm has been considered "anomalous" (minimum Dst reached -105 nT at 07:00 UT on 22 January) because the main storm phase occurred during the northward excursion of the Bz component of interplanetary magnetic fields (IMFs). The monthly mean F10.7 solar flux for the month of January 2005 was 99.0 sfu. The F-region parameters observed by ionosondes at Ramey (RAM; 18.5° N, 67.1° W), Puerto Rico, Jicamarca (JIC; 12.0° S, 76.8° W), Peru, Manaus (MAN; 2.9° S, 60.0° W), and São José dos Campos (SJC; 23.2° S, 45.9° W), Brazil, during 21-22 January (geomagnetically disturbed) and 25 January (geomagnetically quiet) have been analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid uplifting of the F-region peak heights (hpF2/hmF2) and a decrease in the NmF2 coincident with the time of storm sudden commencement (SSC). The observed variations in the F-region ionospheric parameters are compared with the TIMEGCM model run for 21-22 January and the model results show both similarities and differences from the observed results. Average GPS-TEC (21, 22 and 25 January) and phase fluctuations (21, 22, 25, 26 January) observed at Belem (BELE; 1.5° S, 48.5° W), Brasilia (BRAZ; 15.9° S, 47.9° W), Presidente Prudente (UEPP; 22.3° S, 51.4° W), and Porto Alegre (POAL; 30.1° S, 51.1° W), Brazil, are also presented. These GPS stations belong to the RBMC/IBGE network of Brazil. A few hours after the onset of the storm, large enhancements in the VTEC and NmF2 between about 20:00 and 24:00 UT on 21 January were observed at all the stations. However, the increase in VTEC was greatest at the near equatorial station (BELE) and enhancements in VTEC decreased with latitude. It should be pointed out that no phase fluctuations or spread-F were observed in the Latin American

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

    Science.gov (United States)

    Ruhimat, Mamat; Winarko, Anton; Nuraeni, Fitri; Bangkit, Harry; Aris, M. Andi; Suwardi; Sulimin

    2016-11-01

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

  10. Geomagnetic Variation Data - 1-Minute Remote Geophysical Observatory Network (RGON)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data file was generated as part of the International Magnetospheric Study (IMS). The file consists of values of the geomagnetic components D, H, X, Y, Z, and R...

  11. Multisatellite determination of the relativistic electron phase space density at geosynchronous orbit: An integrated investigation during geomagnetic storm times

    Science.gov (United States)

    Chen, Y.; Friedel, R. H. W.; Reeves, G. D.; Cayton, T. E.; Christensen, R.

    2007-11-01

    An integrated investigation method, which can study the relativistic electron phase space density distribution and check the reliability of employed magnetic field models simultaneously, is developed and applied to the geosynchronous orbit region for 53 geomagnetic storms during a ˜190-d period. First, to test how the magnetospheric magnetic field affects the study of phase space density, two approaches are taken on handling the magnetic field model: One is to use an existing empirical model through the whole storm period; the other is to select one from a list of existing magnetic field models for each time bin during the period by fitting to multipoint in situ measurements. The magnetic field models in both approaches are again tested by Liouville's theorem, which requires the conserved phase space density for fixed phase space coordinates given no local losses and sources. Then on the basis of the selected magnetic field model, the phase space density is calculated by transforming the flux data from three Los Alamos National Laboratory geosynchronous satellites. By following the procedure developed here and using the cross-satellite calibration achieved in previous work, we deduce the storm time electron phase space density distribution for the region near geosynchronous orbit, covering a range of L shells with L* centered ˜6. This work establishes the radial phase space density gradient at constant adiabatic invariants as a function of universal time during storm times, and three types of geomagnetic storms are defined according to the degree of energy-dependent enhancements of energetic electrons during recovery phases. Initial results from this study suggest a source outside geosynchronous orbit for low-energy electrons and a major source inside for high-energy electrons.

  12. Responses of the low-latitude ionosphere to very intense geomagnetic storms

    Science.gov (United States)

    Sobral, J. H. A.; Abdu, M. A.; Yamashita, C. S.; Gonzalez, W. D.; de Gonzalez, A. C.; Batista, I. S.; Zamlutti, C. J.; Tsurutani, B. T.

    2001-01-01

    In this work, we investigate the ionospheric responses to exceptionally high-intensity and long-duration magnetic storms over Brazil. Disturbed ionospheric F-region vertical drifts and peak electron density changes observed at the equatorial station Fortaleza - Fz (/3°55'S /38°25'W /dip-3.5°) and the low-latitude station Cachoeira Paulista - CP /(22°41'S /45°00'W dip24°S), for three magnetospheric storm events that occurred in December 1980, April 1981 and September 1982, are analyzed. These storms had minimum Dst indexes /-240,-311 and /-289nT, respectively. The interplanetary magnetic field (Bz) data from the ISEE-3 satellite, the auroral activity index AE, and the ring current index Dst are used as indicators of the magnetospheric conditions. The ionospheric response features are analyzed using the F-layer critical parameters h'F, hpF2 and foF2, from ionograms obtained at Fz and CP. The Bz and the AE index variations were much higher than those in many previous studies. Therefore, many of the observations reported here either have not been observed or are not readily explained by current models for predicting the penetration//dynamo disturbance electric fields. The altitude of the nocturnal ionospheric F-layer at low latitudes may undergo significant variations during storm-time, caused by magnitude variations on the local zonal component of the F-region electric field intensity. During the period studied here, clear association of the F-layer rise (vertical velocity and altitude) and spread-F occurrence is observed. It is shown that the storm-time layer rise has a dominant role on the equatorial spread-F. An attempt is made to identify the origin of electric fields responsible for the disturbed F-layer alterations. The main conclusions of this study are that (a) some effects on the F-layer height and peak electron concentrations are consistent with model predictions. Some others are in discrepancy or have not been either predicted by model studies or

  13. Hemispheric Differences in the Response of the Upper Atmosphere to the August 2011 Geomagnetic Storm: A Simulation Study

    CERN Document Server

    Yiğit, Erdal; Moldwin, Mark B; Immel, Thomas J; Ridley, Aaron J

    2015-01-01

    Using a three-dimensional nonhydrostatic general circulation model, we investigate the response of the thermosphere-ionosphere system to the 5-6 August 2011 major geomagnetic storm. The model is driven by measured storm-time input data of the Interplanetary Magnetic Field (IMF), solar activity, and auroral activity. Simulations for quiet steady conditions over the same period are performed as well in order to assess the response of the neutral and plasma parameters to the storm. During the storm, the high-latitude mean ion flows are enhanced by up to 150-180%. Largest ion flows are found in the main phase of the storm. Overall, the global mean neutral temperature increases by up to 15%, while the maximum thermal response is higher in the winter Southern Hemisphere at high-latitudes than the summer Northern Hemisphere: 40% vs. 20%increase in high-latitude mean temperature, respectively. The global mean Joule heating increases by more than a factor of three. There are distinct hemispheric differences in the mag...

  14. Source identification of moderate (-100 nT geomagnetic storms (Dst < -100 nT) during ascending phase of solar cycle 24

    Science.gov (United States)

    Singh, Abha; Rathore, V. S.; Singh, R. P.; Singh, A. K.

    2017-03-01

    The origin of 39 moderate (-100 nT geomagnetic storms has been investigated using fixed time window and adoptive time window. Coronal mass ejections (CMEs) and corotating interaction region (CIR) are found to be the primary sources. Out of 12 intense geomagnetic storms, 6 (50%) events are associated with unique FSH CMEs, 2 (17%) events with multiple FSH CMEs, 3 events (25%) with partial halo CME with no surface signature and 1 event (8%) is caused due to a CIR. Out of 39 moderate geomagnetic storms 21 (54%) are associated with full halo CME and 5 (13%) with partial halo CME, 4 (10%) storms associated with high speed solar wind from CIR whereas 1 storm has been found to be due to the combined effect of CME and CIR. The remaining 8 (20%) storms have unknown solar origins and were mostly observed when solar activity was at the minimum. The probability of a CIR causing a moderate storm is almost double as compared to an intense storm during the ascending phase of weak solar cycle 24.

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

    Science.gov (United States)

    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.

  16. STEREO and Wind observations of a fast ICME flank triggering a prolonged geomagnetic storm on 5-7 April 2010

    CERN Document Server

    Möstl, Christian; Rollett, Tanja; Farrugia, Charles J; Liu, Ying; Veronig, Astrid M; Leitner, M; Galvin, Antoinette B; Biernat, Helfried K

    2010-01-01

    On 5 April 2010 an interplanetary (IP) shock was detected by the Wind spacecraft ahead of Earth, followed by a fast (average speed 650 km/s) IP coronal mass ejection (ICME). During the subsequent moderate geomagnetic storm (minimum Dst = -72 nT, maximum Kp=8-), communication with the Galaxy 15 satellite was lost. We link images from STEREO/SECCHI to the near-Earth in situ observations and show that the ICME did not decelerate much between Sun and Earth. The ICME flank was responsible for a long storm growth phase. This type of glancing collision was for the first time directly observed with the STEREO Heliospheric Imagers. The magnetic cloud (MC) inside the ICME cannot be modeled with approaches assuming an invariant direction. These observations confirm the hypotheses that parts of ICMEs classified as (1) long-duration MCs or (2) magnetic-cloud-like (MCL) structures can be a consequence of a spacecraft trajectory through the ICME flank.

  17. Atmospheric energy input and ionization by energetic electrons during the geomagnetic storm of 8-9 November 1991

    Science.gov (United States)

    Chenette, D. L.; Datlowe, D. W.; Robinson, R. M.; Schumaker, T. L.; Vondrak, R. R.; Winningham, J. D.

    1993-01-01

    The Atmospheric X-ray Imaging Spectrometer (AXIS) of the Particle Environment Monitor investigation aboard the Upper Atmosphere Research Satellite monitors energy input to the upper atmosphere due to energetic electrons. Analysis of the AXIS data from the major geomagnetic storm of 8-9 November 1991 is presented. During the November storm, electrons above a few keV flowing into a substantially expanded auroral zone provided the bulk of the ionizing power to the upper atmosphere. At the peak of the disturbance the total AXIS-observed power reached 40 GW. On 9 November the whole day average atmospheric ionization rate in the auroral zone at 80 km altitude exceeded the rate due to solar UV and solar X-rays by a factor of over 10 to 100.

  18. Long-term trends of foE and geomagnetic activity variations

    Directory of Open Access Journals (Sweden)

    B. A. de la Morena

    Full Text Available A relationship between foE trends and geomagnetic activity long-term variations has been revealed for the first time. By analogy with earlier obtained results on the foF2 trends it is possible to speak about the geomagnetic control of the foE long-term trends as well. Periods of increasing geomagnetic activity correspond to negative foE trends, while these trends are positive for the decreasing phase of geomagnetic activity. This "natural" relationship breaks down around 1970 (on some stations later when pronounced positive foE trends have appeared on most of the stations considered. The dependence of foE trends on geomagnetic activity can be related with nitric oxide variations at the E-layer heights. The positive foE trends that appeared after the "break down" effect may also be explained by the [NO] decrease which is not related to geomagnetic activity variations. But negative trends or irregular foE variations on some stations for the same time period require some different mechanism. Chemical pollution of the lower thermosphere due to the anthropogenic activity may be responsible for such abnormal foE behavior after the end of the 1960s.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances

  19. Geophysical variables and behavior: XXI. Geomagnetic variation as possible enhancement stimuli for UFO reports preceding earthtremors.

    Science.gov (United States)

    Persinger, M A

    1985-02-01

    The contribution of geomagnetic variation to the occurrence of UFORs (reports of UFOs) within the New Madrid States during the 6-mo. increments before increases in the numbers of IV-V or less intensity earthquakes within the central USA was determined. Although statistically significant zero-order correlations existed between measures of earthquakes, UFORs and geomagnetic variability, the association between the latter two deteriorated markedly when their shared variance with earthquakes was held constant. These outcomes are compatible with the hypothesis that geomagnetic variability (or phenomena associated with it) may enhance UFORs but only if tectonic stress and strain are increasing within the region.

  20. Analysis of High-Latitude lonospheric Processes During HSS and CME-Induced Geomagnetic Storms

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga

    For the first time we compared ionospheric effects of HSS and CME-driven storms at high-latitudes. There were similarities and also differences observed in the development of the storms. (1) Both type of storms exhibited clear negative phase, which resulted in an increase of TOI-breaking-down int...

  1. Storm surge model based on variational data assimilation method

    Institute of Scientific and Technical Information of China (English)

    Shi-li HUANG; Jian XU; De-guan WANG; Dong-yan LU

    2010-01-01

    By combining computation and observation information,the variational data assimilation method has the ability to eliminate errors caused by the uncertainty of parameters in practical forecasting.It was applied to a storm surge model based on unstructured grids with high spatial resolution meant for improving the forecasting accuracy of the storm surge.By controlling the wind stress drag coefficient,the variation-based model was developed and validated through data assimilation tests in an actual storm surge induced by a typhoon.In the data assimilation tests,the model accurately identified the wind stress drag coefficient and obtained results close to the true state.Then,the actual storm surge induced by Typhoon 0515 was forecast by the developed model,and the results demonstrate its efficiency in practical application.

  2. Case study on total electron content enhancements at low latitudes during low geomagnetic activities before the storms

    Directory of Open Access Journals (Sweden)

    Libo Liu

    2008-05-01

    Full Text Available Sometimes the ionospheric total electron content (TEC is significantly enhanced during low geomagnetic activities before storms. In this article, we investigate the characteristics of those interesting TEC enhancements using regional and global TEC data. We analyzed the low-latitude TEC enhancement events that occurred around longitude 120° E on 10 February 2004, 21 January 2004, and 4 March 2001, respectively. The TEC data are derived from regional Global Positioning System (GPS observations in the Asia/Australia sector as well as global ionospheric maps (GIMs produced by Jet Propulsion Laboratory (JPL. Strong enhancements under low geomagnetic activity before the storms are simultaneously presented at low latitudes in the Asia/Australia sector in regional TEC and JPL GIMs. These TEC enhancements are shown to be regional events with longitudinal and latitudinal extent. The regions of TEC enhancements during these events are confined at narrow longitude ranges around longitude 120° E. The latitudinal belts of maxima of enhancements locate around the northern and southern equatorial ionization anomaly (EIA crests, which are consistent with those low-latitude events presented by Liu et al. (2008. During the 4 March 2001 event, the total plasma density Ni observed by the Defense Meteorological Satellite Program (DMSP spacecraft F13 at 840 km altitude are of considerably higher values on 4 March than on the previous day in the TEC enhanced regions. Some TEC enhancement events are possibly due to contributions from auroral/magnetospheric origins; while there are also quasi-periodic enhancement events not related to geomagnetic activity and associated probably with planetary wave type oscillations (e.g. the 6 January 1998 event. Further investigation is warrented to identify/separate contributions from possible sources.

  3. Contribution of solar radiation and geomagnetic activity to global structure of 27-day variation of ionosphere

    Science.gov (United States)

    Yao, Yibin; Zhai, Changzhi; Kong, Jian; Liu, Lei

    2017-04-01

    Twenty-seven-day variation caused by solar rotation is one of the main periodic effects of solar radiation influence on the ionosphere, and there have been many studies on this periodicity using peak electron density N_{mF2} and solar radio flux index F10.7. In this paper, the global electron content (GEC) and observation of Solar EUV Monitor (SEM) represent the whole ionosphere and solar EUV flux, respectively, to investigate the 27-day variation. The 27-day period components of indices (GEC_{27}, SEM_{27}, F10.7_{27}, Ap_{27}) are obtained using Chebyshev band-pass filter. The comparison of regression results indicates that the index SEM has higher coherence than F10.7 with 27-day variation of the ionosphere. The regression coefficients of SEM_{27 } varied from 0.6 to 1.4 and the coefficients of Ap_{27} varied from - 0.6 to 0.3, which suggests that EUV radiation seasonal variations are the primary driver for the 27-day variations of the ionosphere for most periods. TEC map grid points on three meridians where IGS stations are dense are selected for regression, and the results show that the contribution of solar EUV radiation is positive at all geomagnetic latitudes and larger than geomagnetic activity in most latitudes. The contribution of geomagnetic activity is negative at high geomagnetic latitude, increasing with decreasing geomagnetic latitudes, and positive at low geomagnetic latitudes. The global structure of 27-day variation of ionosphere is presented and demonstrates that there are two zonal anomaly regions along with the geomagnetic latitudes lines and two peaks in the north of Southeast Asia and the Middle Pacific where TEC_{27} magnitude values are notably larger than elsewhere along zonal anomaly regions.

  4. Latitudinal and Seasonal Investigations of Storm-Time TEC Variation

    Science.gov (United States)

    Adimula, I. A.; Oladipo, O. A.; Adebiyi, S. J.

    2016-07-01

    The ionosphere responds markedly and unpredictably to varying magnetospheric energy inputs caused by solar disturbances on the geospace. Knowledge of the impact of the space weather events on the ionosphere is important to assess the environmental effect on the operations of ground- and space-based technologies. Thus, global positioning system (GPS) measurements from the international GNSS service (IGS) database were used to investigate the ionospheric response to 56 geomagnetic storm events at six different latitudes comprising the northern and southern hemispheres in the Afro-European sector. Statistical distributions of total electron content (TEC) response show that during the main phase of the storms, enhancement of TEC is more pronounced in most of the seasons, regardless of the latitude and hemisphere. However, a strong seasonal dependence appears in the TEC response during the recovery phase. Depletion of TEC is majorly observed at the high latitude stations, and its appearance at lower latitudes is seasonally dependent. In summer hemisphere, the depletion of TEC is more pronounced in nearly all the latitudinal bands. In winter hemisphere, enhancement as well as depletion of TEC is observed over the high latitude, while enhancement is majorly observed over the mid and low latitudes. In equinoxes, the storm-time TEC distribution shows a fairly consistent characteristic with the summer distribution, particularly in the northern hemisphere.

  5. Arabidopsis thaliana root elongation growth is sensitive to lunisolar tidal acceleration and may also be weakly correlated with geomagnetic variations

    Science.gov (United States)

    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

  6. Effects of the intense geomagnetic storm of September-October 2012 on the equatorial, low- and mid-latitude F region in the American and African sector during the unusual 24th solar cycle

    Science.gov (United States)

    de Jesus, R.; Fagundes, P. R.; Coster, A.; Bolaji, O. S.; Sobral, J. H. A.; Batista, I. S.; de Abreu, A. J.; Venkatesh, K.; Gende, M.; Abalde, J. R.; Sumod, S. G.

    2016-02-01

    The main purpose of this paper is to investigate the response of the ionospheric F layer in the American and African sectors during the intense geomagnetic storm which occurred on 30 September-01 October 2012. In this work, we used observations from a chain of 20 GPS stations in the equatorial, low- and mid-latitude regions in the American and African sectors. Also, in this study ionospheric sounding data obtained during 29th September to 2nd October, 2012 at Jicamarca (JIC), Peru, São Luis (SL), Fortaleza (FZ), Brazil, and Port Stanley (PST), are presented. On the night of 30 September-01 October, in the main and recovery phase, the h´F variations showed an unusual uplifting of the F region at equatorial (JIC, SL and FZ) and mid- (PST) latitude stations related with the propagations of traveling ionospheric disturbances (TIDs) generated by Joule heating at auroral regions. On 30 September, the VTEC variations and foF2 observations at mid-latitude stations (American sector) showed a long-duration positive ionospheric storm (over 6 h of enhancement) associated with large-scale wind circulations and equatorward neutral winds. Also, on 01 October, a long-duration positive ionospheric storm was observed at equatorial, low- and mid- latitude stations in the African sector, related with the large-scale wind circulations and equatorward neutral winds. On 01 and 02 October, positive ionospheric storms were observed at equatorial, low- and mid-latitude stations in the American sector, possibly associated with the TIDs and an equatorward neutral wind. Also, on 01 October negative ionospheric storms were observed at equatorial, low- and mid-latitude regions in the American sector, probably associated with the changes in the O/N2 ratio. On the night of 30 September-01 October, ionospheric plasma bubbles were observed at equatorial, low- and mid- latitude stations in the South American sector, possibly associated with the occurrence of geomagnetic storm.

  7. Variation of curve number with storm depth

    Science.gov (United States)

    Banasik, K.; Hejduk, L.

    2012-04-01

    The NRCS Curve Number (known also as SCS-CN) method is well known as a tool in predicting flood runoff depth from small ungauged catchment. The traditional way of determination the CNs, based on soil characteristics, land use and hydrological conditions, seemed to have tendency to overpredict the floods in some cases. Over 30 year rainfall-runoff data, collected in two small (A=23.4 & 82.4 km2), lowland, agricultural catchments in Center of Poland (Banasik & Woodward 2010), were used to determine runoff Curve Number and to check a tendency of changing. The observed CN declines with increasing storm size, which according recent views of Hawkins (1993) could be classified as a standard response of watershed. The analysis concluded, that using CN value according to the procedure described in USDA-SCS Handbook one receives representative value for estimating storm runoff from high rainfall depths in the analyzes catchments. This has been confirmed by applying "asymptotic approach" for estimating the watershed curve number from the rainfall-runoff data. Furthermore, the analysis indicated that CN, estimated from mean retention parameter S of recorded events with rainfall depth higher than initial abstraction, is also approaching the theoretical CN. The observed CN, ranging from 59.8 to 97.1 and from 52.3 to 95.5, in the smaller and the larger catchment respectively, declines with increasing storm size, which has been classified as a standard response of watershed. The investigation demonstrated also changeability of the CN during a year, with much lower values during the vegetation season. Banasik K. & D.E. Woodward (2010). "Empirical determination of curve number for a small agricultural watrshed in Poland". 2nd Joint Federal Interagency Conference, Las Vegas, NV, June 27 - July 1, 2010 (http://acwi.gov/sos/pubs/2ndJFIC/Contents/10E_Banasik_ 28_02_10. pdf). Hawkins R. H. (1993). "Asymptotic determination of curve numbers from data". Journal of Irrigation and Drainage

  8. Ionospheric electron density perturbations during the 7-10 March 2012 geomagnetic storm period

    Science.gov (United States)

    Belehaki, Anna; Kutiev, Ivan; Marinov, Pencho; Tsagouri, Ioanna; Koutroumbas, Kostas; Elias, Panagiotis

    2017-02-01

    From 7 to 10 March 2012 a series of magnetospheric disturbances caused perturbations in the ionospheric electron density. Analyzing the interplanetary causes in each phase of this disturbed period, in comparison with the total electron content (TEC) disturbances, we have concluded that the interplanetary solar wind controls largely the ionospheric response. An interplanetary shock detected at 0328UT on 7 March caused the formation of prompt penetrating electric fields in the dayside that transported plasma from the near-equatorial region to higher in attitudes and latitudes forming a giant plasma fountain which is part of the so-called dayside ionospheric super-fountain. The super-fountain produces an increase in TEC which is the dominant effect at middle latitude, masking the effect of the negative storm. Simultaneously, inspecting the TEC maps, we found evidence for a turbulence in TEC propagating southward probably caused by large scale travelling ionospheric disturbances (LSTIDs) linked to auroral electrojet intensification. On 8 March, a magnetospheric sudden impulse at 1130UT accompanied with strong pulsations in all interplanetary magnetic field (IMF) components and with northward Bz component during the growth phase of the storm. These conditions triggered a pronounced directly driven substorm phase during which we observe LSTID. However, the analysis of DMSP satellite observations, provided with strong evidence for Sub-Auroral Polarization Streams (SAPS) formation that erode travelling ionospheric disturbances (TID) signatures. The overall result of these mechanisms can be detected in maps of de-trended TEC, but it is difficult to identify separately each of the sources of the observed perturbations, i.e. auroral electrojet activity and LSTIDs, super-fountain and SAPS. In order to assess the capability of the ionospheric profiler called Topside Sounder Model - assisted Digisonde (TaD model) to detect such perturbations in the electron density, electron

  9. The quasi-biennial variation in the geomagnetic field: a global characteristics analysis

    Science.gov (United States)

    Ou, Jiaming; Du, Aimin

    2016-04-01

    exhibits distinct anisotropic in the local time distribution. The QBO of the X and Z components are both stronger over LT 00:00-06:00. The results of spherical harmonic analysis indicate that the QBO is mainly contributed by the external sources. The QBO is highly correlated with various parameters of solar activity, solar wind at 1AU, and geomagnetic activity. Reference 1. Sugiura, M. (1976). Quasi-biennial geomagnetic variation caused by the Sun. Geophys. Res. Lett., 3(11), 643-646. 2. Silva, L., Jackson, L., and Mound, J., (2012), Assessing the importance and expression of the 6 year geomagnetic oscillation, J. Geophys. Res.: Solid Earth (1978-2012), 117.

  10. Similarity and differences in morphology and mechanisms of the foF2 and TEC disturbances during the geomagnetic storms on 26-30 September 2011

    Science.gov (United States)

    Klimenko, Maxim V.; Klimenko, Vladimir V.; Zakharenkova, Irina E.; Ratovsky, Konstantin G.; Korenkova, Nina A.; Yasyukevich, Yury V.; Mylnikova, Anna A.; Cherniak, Iurii V.

    2017-08-01

    This study presents an analysis of the ground-based observations and model simulations of ionospheric electron density disturbances at three longitudinal sectors (eastern European, Siberian and American) during geomagnetic storms that occurred on 26-30 September 2011. We use the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) to reveal the main mechanisms influencing the storm-time behavior of the total electron content (TEC) and the ionospheric F2 peak critical frequency (foF2) during different phases of geomagnetic storms. During the storm's main phase the long-lasting positive disturbances in TEC and foF2 at sunlit mid-latitudes are mainly explained by the storm-time equatorward neutral wind. The effects of eastward electric field can only explain the positive ionospheric storm in the first few hours of the initial storm phase. During the main phase the ionosphere was more changeable than the plasmasphere. The positive disturbances in the electron content at the plasmaspheric heights (800-20 000 km) at high latitudes can appear simultaneously with the negative disturbances in TEC and foF2. The daytime positive disturbances in foF2 and TEC occurred at middle and low latitudes and at the Equator due to n(O) / n(N2) enhancement during later stage of the main phase and during the recovery phase of the geomagnetic storm. The plasma tube diffusional depletion and negative disturbances in electron and neutral temperature were the main formation mechanisms of the simultaneous formation of the positive disturbances in foF2 and negative disturbances in TEC at low latitudes during the storm's recovery phase.

  11. Annual Variations of the Geomagnetic Field in the Earth's Polar Regions

    Science.gov (United States)

    Ou, Jiaming; Du, Aimin

    2017-04-01

    The annual variations of the geomagnetic field play an important role in the coupling processes between the solar wind, magnetosphere and ionosphere. The annual variation is a well-established feature of the geomagnetic field, and usually is applied for modeling the conductivity of the lower mantle [Parkinson, 1983], and for long-term space weather forecasting [Bartels, 1932; Malin and Mete Isikara, 1976; Gonzalez et al., 1994]. Considerable effort has been devoted toward understanding the causes of the geomagnetic field variations, but the suggested physical mechanisms differ widely. The annual variation is relatively weak in many magnetic indices, but it has a distinct signature in the geomagnetic components. Thus, we use the components for this analysis. The components have a positive peak in northern summer and a negative dip in winter [Vestine, 1954]. Vestine [1954] suggested that the annual variation is caused by an ionospheric dynamo in which electric currents in the ionosphere are generated by meridional winds. The winds blow from north-to-south during northern summer, and south-to-north in northern winter. Malin and Mete Isikara [1976], using near-midnight geomagnetic data, concluded that the annual variation results from a latitudinal movement of the auroral electrojet or the ring current. Stauning [2011] derived of the seasonal variation of the quiet daily variations and examined the influence of the sector structure of the interplanetary magnetic field. Ziegger and Mursula [1998] have suggested a third mechanism: that the cause is related to an asymmetric solar wind speed distribution across the heliographic equator. In this paper, we study the annual variation problem using long-term magnetic observation and ionospheric conductivity. The sunlight incident on the ionosphere will be calculated. Although a global analysis is done, particular focus will be placed on the polar regions. This study covers the interval 1990-2010, and the cause of the well

  12. Automatic selection of Dst storms and their seasonal variations in two versions of Dst in 50 years

    Science.gov (United States)

    Balan, N.; Tulasiram, S.; Kamide, Y.; Batista, I. S.; Souza, J. R.; Shiokawa, K.; Rajesh, P. K.; Victor, N. J.

    2017-04-01

    A computer program is developed to automatically identify the geomagnetic storms in Dst index by applying four selection criteria that minimize non-storm-like fluctuations. The program is used to identify the storms in Kyoto Dst and USGS Dst in 50 years (1958-2007). The identified storms (DstMin ≤ -50 nT) are used to investigate their seasonal variations. It is found that the overall seasonal variations of the storm parameters such as occurrence, average intensity (average DstMin) and average strength (average ⟨DstMP⟩) in both versions of Dst exhibit clear semiannual variations with equinoctial maxima and solstice minima; and the maxima and minima in intensity and strength ( ±17% each) are less than those in occurrence ( ±28%). Wavelet spectra of the storms reveal the existence of distinct semiannual component in four solar cycles (SCs 20-23) and weak longer and shorter-period components in some SCs. The semiannual variation observed also in the mean energy input during the main phase (MP) of the storms estimated from Dst is interpreted in terms of the (1) equinoctial mechanism based on the varying angle between the Earth-Sun line and Earth's dipole axis and (2) Russell-Mcpherron effect based on the varying angle between the GSM Z-axis and GSE Y-axis; and the yearly range of the dipole tilt angle µ (23.2°) involved in the equinoctial mechanism is found larger than the title angle θ (16.3°) involved in the RM effect.[Figure not available: see fulltext.

  13. A density-temperature description of the outer electron radiation belt during geomagnetic storms

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, Joseph E [Los Alamos National Laboratory; Cayton, Thomas E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV

    2009-01-01

    Electron flux measurements from 7 satellites in geosynchronous orbit from 1990-2007 are fit with relativistic bi-Maxwellians, yielding a number density n and temperature T description of the outer electron radiation belt. For 54.5 spacecraft years of measurements the median value ofn is 3.7x10-4 cm-3 and the median value ofT is 142 keY. General statistical properties of n, T, and the 1.1-1.5 MeV flux J are investigated, including local-time and solar-cycle dependencies. Using superposed-epoch analysis triggered on storm onset, the evolution of the outer electron radiation belt through high-speed-steam-driven storms is investigated. The number density decay during the calm before the storm is seen, relativistic-electron dropouts and recoveries from dropout are investigated, and the heating of the outer electron radiation belt during storms is examined. Using four different triggers (SSCs, southward-IMF CME sheaths, southward-IMF magnetic clouds, and minimum Dst), CME-driven storms are analyzed with superposed-epoch techniques. For CME-driven storms an absence of a density decay prior to storm onset is found, the compression of the outer electron radiation belt at time of SSC is analyzed, the number-density increase and temperature decrease during storm main phase is seen, and the increase in density and temperature during storm recovery phase is observed. Differences are found between the density-temperature and the flux descriptions, with more information for analysis being available in the density-temperature description.

  14. A density-temperature description of the outer electron radiation belt during geomagnetic storms

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, Joseph E [Los Alamos National Laboratory; Cayton, Thomas E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV

    2009-01-01

    Electron flux measurements from 7 satellites in geosynchronous orbit from 1990-2007 are fit with relativistic bi-Maxwellians, yielding a number density n and temperature T description of the outer electron radiation belt. For 54.5 spacecraft years of measurements the median value ofn is 3.7x10-4 cm-3 and the median value ofT is 142 keY. General statistical properties of n, T, and the 1.1-1.5 MeV flux J are investigated, including local-time and solar-cycle dependencies. Using superposed-epoch analysis triggered on storm onset, the evolution of the outer electron radiation belt through high-speed-steam-driven storms is investigated. The number density decay during the calm before the storm is seen, relativistic-electron dropouts and recoveries from dropout are investigated, and the heating of the outer electron radiation belt during storms is examined. Using four different triggers (SSCs, southward-IMF CME sheaths, southward-IMF magnetic clouds, and minimum Dst), CME-driven storms are analyzed with superposed-epoch techniques. For CME-driven storms an absence of a density decay prior to storm onset is found, the compression of the outer electron radiation belt at time of SSC is analyzed, the number-density increase and temperature decrease during storm main phase is seen, and the increase in density and temperature during storm recovery phase is observed. Differences are found between the density-temperature and the flux descriptions, with more information for analysis being available in the density-temperature description.

  15. GPS phase scintillation during the geomagnetic storm of March 17, 2015: The relation to auroral electrojet currents

    DEFF Research Database (Denmark)

    Prikryl, Paul; Ghoddousi-Fard, Reza; Connors, Martin

    and magnetometers. GPS phase scintillation index is computed for L1 signal sampled at the rate of 50 Hz by specialized GPS scintillation receivers of the Expanded Canadian High Arctic Ionospheric Network (ECHAIN). To further extend the geographic coverage, the phasescintillation proxy index is obtained from......-enhanced plasma density (SED) and in the auroral oval during energetic particle precipitation events, substorms and pseudo-breakups in particular. In this paper we examine the relation to auroral electrojet currents observed by arrays of ground-based magnetometers and energetic particle precipitation observed......Ionospheric irregularities cause rapid fluctuations of radio wave amplitude and phase that candegrade GPS positional accuracy and affect performance of radio communication and navigation systems. The ionosphere becomes particularly disturbed during geomagnetic storms caused by impacts of coronal...

  16. Multi-spacecraft testing of time-dependent interplanetary MHD models for operational forecasting of geomagnetic storms

    Science.gov (United States)

    Dryer, M.; Smith, Z. K.

    1989-01-01

    An MHD 2-1/2D, time-dependent model is used, together with observations of six solar flares during February 3-7, 1986, to demonstrate global, large-scale, compound disturbances in the solar wind over a wide range of heliolongitudes. This scenario is one that is likely to occur many times during the cruise, possibly even encounter, phases of the Multi-Comet Mission. It is suggested that a model such as this one should be tested with multi-spacecraft data (such as the MCM and earth-based probes) with several goals in view: (1) utility of the model for operational real-time forecasting of geomagnetic storms, and (2) scientific interpretation of certain forms of cometary activities and their possible association with solar-generated activity.

  17. Time-causal decomposition of geomagnetic time series into secular variation, solar quiet, and disturbance signals

    Science.gov (United States)

    Rigler, E. Joshua

    2017-04-26

    A theoretical basis and prototype numerical algorithm are provided that decompose regular time series of geomagnetic observations into three components: secular variation; solar quiet, and disturbance. Respectively, these three components correspond roughly to slow changes in the Earth’s internal magnetic field, periodic daily variations caused by quasi-stationary (with respect to the sun) electrical current systems in the Earth’s magnetosphere, and episodic perturbations to the geomagnetic baseline that are typically driven by fluctuations in a solar wind that interacts electromagnetically with the Earth’s magnetosphere. In contrast to similar algorithms applied to geomagnetic data in the past, this one addresses the issue of real time data acquisition directly by applying a time-causal, exponential smoother with “seasonal corrections” to the data as soon as they become available.

  18. Geomagnetic imprinting predicts spatio-temporal variation in homing migration of pink and sockeye salmon.

    Science.gov (United States)

    Putman, Nathan F; Jenkins, Erica S; Michielsens, Catherine G J; Noakes, David L G

    2014-10-06

    Animals navigate using a variety of sensory cues, but how each is weighted during different phases of movement (e.g. dispersal, foraging, homing) is controversial. Here, we examine the geomagnetic and olfactory imprinting hypotheses of natal homing with datasets that recorded variation in the migratory routes of sockeye (Oncorhynchus nerka) and pink (Oncorhynchus gorbuscha) salmon returning from the Pacific Ocean to the Fraser River, British Columbia. Drift of the magnetic field (i.e. geomagnetic imprinting) uniquely accounted for 23.2% and 44.0% of the variation in migration routes for sockeye and pink salmon, respectively. Ocean circulation (i.e. olfactory imprinting) predicted 6.1% and 0.1% of the variation in sockeye and pink migration routes, respectively. Sea surface temperature (a variable influencing salmon distribution but not navigation, directly) accounted for 13.0% of the variation in sockeye migration but was unrelated to pink migration. These findings suggest that geomagnetic navigation plays an important role in long-distance homing in salmon and that consideration of navigation mechanisms can aid in the management of migratory fishes by better predicting movement patterns. Finally, given the diversity of animals that use the Earth's magnetic field for navigation, geomagnetic drift may provide a unifying explanation for spatio-temporal variation in the movement patterns of many species. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  19. The geomagnetic field intensity variations in the Iberian Peninsula during the last millennium

    Science.gov (United States)

    Nachasova, I. E.; Akimova, S. V.

    2015-09-01

    The pattern of variations in the intensity of the geomagnetic field starting from the middle of the sixth millennium B.C. is reconstructed from the data about the intensity of the ancient geomagnetic field in the region of the Iberian Peninsula provided by the archaeomagnetic studies of ceramics from archaeological monuments. In this time interval, the intensity of the field widely varies from ~30 to ~90 µT. The smooth variation of the field is superimposed by the variations with characteristic times from thousands to hundreds of years. The intensity variations can be subdivided into two groups: rather sharp variations with a characteristic duration of about 200 years and smooth quasi-harmonic fluctuations with a duration of a few hundred years.

  20. Ionospheric response to the 17-18 March 2015 geomagnetic storm as seen from multiple TEC and NmF2 measurements along 100°E

    Science.gov (United States)

    Bhuyan, Pradip; Yokoyama, Tatsuhiro; Kalita, Bitap Raj; Seemala, G. K.; Hazarika, Rumajyoti; Komolmis, Tharadol; Yatini, Clara; Chakrabarty, Dibyendu; Supnithi, Pornchai

    2016-07-01

    The response of the ionosphere along 100°E to the strong geomagnetic storm of 17-18 March 2015 has been investigated combining TEC and NmF2 data from multiple stations spanning low latitudes in the northern and southern hemispheres to the equator. The GPS TEC data measured over Dibrugarh (27.4°N, 95°E), Kohima (25.6°N, 94.1°E) and Ahmedabad (23.0°N, 72.5°E) and NmF2 measured along a chain of ionosonde stations Dibrugarh (27.5°N, 95°E), Chiang Mai (18.76ºN, 98.93ºE), Chumphon (10.72ºN,99.37ºE), Kototabang (0.2ºS,100.32ºE) and Cocos Island (12.2ºS,96.8ºE ) were used to examine the signature of the storm around the low-mid latitude ionosphere in this sector. Nearly similar TEC variation has been observed over Dibrugarh and Kohima located at the northern edge of the EIA. The maximum TEC on 18 March over Dibrugarh and Kohima was reduced by more than ~80 TECU compared to that on the geomagnetically quiet day of 16 March 2015. In contrast to the substantial reduction in TEC over ~100°E TEC from the ~75°E longitude station Ahmedabad showed insignificant variations on the same day. Strong reduction in NmF2 at the crest of the anomaly in both northern and southern hemisphere (Dibrugarh, Ching Mai and Cocos Island) and enhancement near the equator (Cumphon and Kototbang) has been observed. The O/N2 ratio as obtained from the TIMED/GUVI reduced substantially along 100°E on 18 March compared to other longitude sectors. Equatorward meridional winds depleted the ionization at the crest region and enhanced the same near the equator. No L band scintillation was observed in the evening of 17 March at Dibrugarh and Kohima indicating absence of F region irregularity along this longitude while strong scintillations were observed at 75°E. The reversal of the IMF Bz from southward to northward direction in the dusk to evening sector inhibited the growth of the irregularity due to reversal of the PPEF at 100°E while the PPEF favoured generation and growth of Spread F

  1. Middle- and low-latitude ionosphere response to 2015 St. Patrick's Day geomagnetic storm

    Science.gov (United States)

    Nava, B.; Rodríguez-Zuluaga, J.; Alazo-Cuartas, K.; Kashcheyev, A.; Migoya-Orué, Y.; Radicella, S. M.; Amory-Mazaudier, C.; Fleury, R.

    2016-04-01

    This paper presents a study of the St Patrick's Day storm of 2015, with its ionospheric response at middle and low latitudes. The effects of the storm in each longitudinal sector (Asian, African, American, and Pacific) are characterized using global and regional electron content. At the beginning of the storm, one or two ionospheric positive storm effects are observed depending on the longitudinal zones. After the main phase of the storm, a strong decrease in ionization is observed at all longitudes, lasting several days. The American region exhibits the most remarkable increase in vertical total electron content (vTEC), while in the Asian sector, the largest decrease in vTEC is observed. At low latitudes, using spectral analysis, we were able to separate the effects of the prompt penetration of the magnetospheric convection electric field (PPEF) and of the disturbance dynamo electric field (DDEF) on the basis of ground magnetic data. Concerning the PPEF, Earth's magnetic field oscillations occur simultaneously in the Asian, African, and American sectors, during southward magnetization of the Bz component of the interplanetary magnetic field. Concerning the DDEF, diurnal magnetic oscillations in the horizontal component H of the Earth's magnetic field exhibit a behavior that is opposed to the regular one. These diurnal oscillations are recognized to last several days in all longitudinal sectors. The observational data obtained by all sensors used in the present paper can be interpreted on the basis of existing theoretical models.

  2. Observations of energetic helium ions in the earth's radiation belts during a sequence of geomagnetic storms

    Science.gov (United States)

    Spjeldvik, W. N.; Fritz, T. A.

    1981-01-01

    Observations of energetic (MeV) helium ions made with Explorer 45 during a sequence of magnetic storms during June through December of 1972 are presented. It is noted that the first of these storms started on June 17 and had a Dst index excursion to -190 gamma and that the MeV helium ions were perturbed primarily beyond 3 earth radii in the equatorial radiation belts with a typical flux increase of an order of magnitude at L equal to 4. The second storm period was in August and was associated with very major solar flare activity. While the Dst extremum was at best 35 gamma less than the June storm, this period can be characterized as irregular (or multi-storm) with strong compression of the magnetosphere and very large (order of magnitude) MeV helium ion flux enhancements down to L approximately equal to 2. After this injection, the trapped helium ion fluxes showed positive spherical slope with the peak beyond 3.15 MeV at L equal to 2.5; at the lowest observable L shells, little flux decay was seen during the remainder of the year.

  3. A Hyperbolic Decay of the Dst Index during the Recovery Phase of Intense Geomagnetic Storms

    CERN Document Server

    Aguado, J; Saiz, E; Cerrato, Y

    2014-01-01

    What one commonly considers for reproducing the recovery phase of magnetosphere, as seen by the Dst index, is exponential function. However, the magnetosphere recovers faster in the first hours than in the late recovery phase. The early steepness followed by the late smoothness in the magnetospheric response is a feature that leads to the proposal of a hyperbolic decay function to reproduce the recovery phase, instead of the exponential function. A superposed epoch analysis of recovery phases of intense storms from 1963-2006 was performed, categorizing the storms by their intensity into five subsets. The hyperbolic decay function reproduces experimental data better than what the exponential function does for any subset of storms, which indicates a non-linear coupling between dDst/dt and Dst. Moreover, this kind of mathematical function, where the degree of reduction of the Dst index depends on time, allows for explaining different lifetimes of the physical mechanisms involved in the recovery phase and provide...

  4. Magnetic storms and variations in hormone levels among residents of North Polar area - Svalbard

    Science.gov (United States)

    Breus, Tamara; Zenchenko, Tatiana; Boiko, Evgeni

    It was previously shown that magnetic storms lead to an increase in the level of cortisol and noradrenalin in healthy and sick people with cardiovascular diseases [Breus Rapoport. 2003]. However, in the healthy group in the cited study was only 4 people and it seemed that these results need to be checked. In the present work the 4 examinations (January, March, June, October) of large groups of healthy inhabitants of high latitudes (Svalbard, the most northerly in the world year-round inhabited settlements) on the blood levels of adrenal hormones (cortisol) and thyroid hormones (triiodothyronine (T3 ) and thyroxine T4) have been done. The aim was to study the possible sensitivity of these biochemical parameters in three independent groups of people living in this region (men working underground (364 samples), the men working on the ground (274 samples) and women (280 samples)) to variations in external natural factors of high latitudes. For the analysis we used the following parameters of space and terrestrial weather :index of intensity of solar radio emission at a wavelength 10.7sm (RF10.7), planetary geomagnetic activity index - daily Kp index ( Kp) , the daily average Ap index ( Ap) , the maximum per every 3 -hour Kp index ) as well as the daily average indicators of flow rate of galactic cosmic rays neutron component (N), atmospheric pressure ( RATM ) and its rate of change ( the difference between the Ratm today and yesterday ) according to the geophysical station Oulu (Finland , http://cosmicrays.oulu.fi/). The obtained data indicate that the most expressed dependence of the level of studied three hormones is from the level of geomagnetic activity (GMA)-Kp, Ap, Kpmax - 3h. For two of the four seasons (June and October) with increasing levels of GMA a significant (p hormone secretion with increasing levels of GMA from 18 to 30% of the average amplitude of intragroup variations). Thus, we showed for the first time that at high latitudes increase in the level of

  5. Long-term analysis between radio occultation and ionosonde peak electron density and height during geomagnetic storms

    Science.gov (United States)

    Habarulema, John Bosco; Carelse, Suné Arlene

    2016-05-01

    For the first time, a long-term comparative analysis of radio occultation (RO) maximum electron density and peak height of the F2 layer (NmF2 and hmF2) with ionosonde data is presented during geomagnetic storm periods. Using the optimum spatial resolution of 4.5° × 4.5° in both latitude and longitude space over Grahamstown, GR13L(33.3°S, 26.5°E), South Africa, RO NmF2 and hmF2 (from CHAMP and COSMIC/FORMOSAT-3) are directly compared to ionosonde values within 15 min of ionosonde observational data from 2003 to end of May 2015. This study provides for the first time the deviation of RO data from ionosonde data on a long-term scale during disturbed conditions in a midlatitude region. We have found that maximum deviations between RO and ionosonde hmF2/NmF2 occur during the high solar activity periods. For some storms, deviations between RO and ionosonde hmF2 can reach values just over 30 km and 85 km during 2005-2010 and 2011-2015, respectively. Overall, statistical results show that hmF2 and NmF2 from these independent data sets agree to within ˜9% and 21% (1 standard deviation, 1σ) from 2003 to 2015. While the deviation can be large during some storm events, statistically and based on ionosonde data, RO F2 peak parameters in midlatitudes are not degraded significantly during disturbed conditions and can therefore be reliably used to study ionospheric dynamics during extreme space weather events.

  6. Simulation of low latitude ionospheric response to 2015 St. Patrick's Day super geomagnetic storm over Indian longitude sector

    Science.gov (United States)

    Mohan Joshi, Lalit; Sripathi, Samireddipelle; Singh, Ram

    2016-07-01

    We present low latitude ionospheric response over Indian longitude to the recent super geomagnetic storm of 17 March 2015, using the SAMI2 model which incorporates ionosonde derived vertical drift impacted by prompt penetration eastward electric field occurring during the evening Prereversal Enhancement (PRE) in the vertical drift. The importance of this storm is that (a) Dst reaches as low as -228 nT and (b) prompt penetration of eastward electric field coincided with evening hours PRE. The daytime vertical EXB drifts in the SAMI2 model are, however, considered based on Scherliess-Fejer model. The simulations indicate a significant enhancement in F layer height and equatorial ionization anomaly (EIA) in the post sunset hours on 17 March 2015 vis-a-vis quiet day. The model simulations during recovery phase, considering disturbance dynamo vertical EXB drift along with equatorward disturbance wind, indicates suppression of the daytime EIA. SAMI2 simulations considering the disturbance wind during the recovery phase suggests that equatorward wind enhances the ionospheric density in the low latitude, however, its role in the formation of the EIA depends on the polarity of the zonal electric field. Comparison of model derived total electron content (TEC) with the TEC from ground GPS receivers indicate that model does reproduce enhancement of the EIA during the main phase and suppression of the EIA during the recovery phase of the super storm. However, peculiarities pertaining to the ionospheric response to prompt penetration electric field in the Indian sector vis-a-vis earlier reports from American sector will be discussed.

  7. Long-term variations of solar magnetic fields derived from geomagnetic data

    CERN Document Server

    Georgieva, K; Nagovitsyn, Yu A

    2013-01-01

    Sunspots are dark spots on the solar surface associated with strong magnetic fields. The number, area, and brightness of sunspots are supposed to reflect the intensity of the solar magnetic fields and are often used as proxies for their long-term variations. However, the correlations between the sunspot parameters and solar magnetic fields are not constant, and the causes and the time profiles of the variations in these correlations are not quite clear. Therefore, the sunspot data alone cannot be used as proxy for deriving the variations of the sunspot magnetic fields for periods when no instrumental measurements are available. But the Earth is a sort of a probe reacting to interplanetary disturbances which are manifestation of the solar magnetic fields, so records of the geomagnetic activity can be used as diagnostic tools for reconstructing past solar magnetic fields evolution. In the present study we combine sunspot and geomagnetic data to estimate the long-term variations of sunspot magnetic fields.

  8. Variations in the intensity of the geomagnetic field in Siberia during the last 13000 years

    Science.gov (United States)

    Nachasova, I. E.; Burakov, K. S.; Pilipenko, O. V.

    2015-01-01

    The thermal magnetization of the samples from the archaeological sites in Siberia is studied. The magnetization of the collected samples was studied using the authors' modification of the Thellier method amended by the magnetic anisotropy and chemical alterations. Resulting from the study of the burned material from the Kazachka site, the time series of the geomagnetic field intensity in Siberia spanning the time interval from 10000 to 1000 B.C. is obtained. These data are unique in terms of the duration and representativeness. For the first time, the main variation in the intensity of the geomagnetic field is traced by studying the magnetization of the samples from a single archeological site. The pattern of the variations in the intensity of the geomagnetic field in Siberia from 11000 B.C. to 2000 A.D., which is reconstructed from the data of the Kazachka, Ust-Karenga, and some other sites of Cis-Baikalia, indicates that the characteristics time of the long-period oscillation in the intensity of the geomagnetic field is about 8000 years. It also suggests the existence of rapid variations superimposed on the main oscillation.

  9. Separation of variations of the geomagnetic field into normal and anomalous parts on a bounded territory

    Science.gov (United States)

    Zhdanov, M. S.; Plotnikov, S. V.

    1981-12-01

    A method based on convolution integrals is developed for separating geomagnetic variations into normal and anomalous parts. It is shown for a number of typical models of normal geoelectric section that the kernels of the integral transforms have the form of spatial windows which fluctuate (depending on the variation period) from several tens to several hundreds of kilometers. This indicates the possibility of separating fields specified on a bounded territory into normal and anomalous parts.

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

    Science.gov (United States)

    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.

  11. Variations in geomagnetic intensity and temperature in the second Millennium B.C. in Spain

    Science.gov (United States)

    Nachasova, I. E.; Burakov, K. S.

    2012-05-01

    The Bronze ceramics of the Baeza archeological monument in Spain is studied by archaeomagnetic methods. In the 19th and 18th centuries B.C, the intensity of the geomagnetic field varied from 40 to 60 mkT. The variations are smooth; they attained their maximum in the 16th to 15th centuries B.C. The obtained data on the variations in the geomagnetic intensity perfectly agree with the results of previous investigations for the ceramics from the Bronze Age multilayered archeological monuments Azuer and Ubeda. The temperature in the region of the Baeza monument is estimated in the interval from the 18th to the 13th centuries B.C. It experiences wave-like variation, ranging from ˜15 to 23°C and attains its maximum in the 16th century B.C.

  12. Solar cycle 22 control on daily geomagnetic variation at Terra Nova Bay (Antarctica

    Directory of Open Access Journals (Sweden)

    P. Palangio

    1998-06-01

    Full Text Available Nine summer geomagnetic observatory data (1986-1995 from Terra Nova Bay Base, Antarctica (Lat.74.690S, Long. 164.120E, 80.040S magnetic latitude are used to investigate the behaviour of the daily variation of the geomagnetic field at polar latitude. The instrumentation includes a proton precession magnetometer for total intensity |F| digital recordings; DI magnetometers for absolute measuring of the angular elements D and I and a three axis flux-gate system for acquiring H,D Z time variation data. We find that the magnetic time variation amplitude follows the solar cycle evolution and that the ratio between minimum solar median and maximum solar median is between 2-3 for intensive elements (H and Z and 1.7 for declination(D. The solar cycle effect on geomagnetic daily variation elements amplitude in Antarctica, in comparison with previous studies, is then probably larger than expected. As a consequence, the electric current system that causes the daily magnetic field variation reveals a quite large solar cycle effect at Terra Nova Bay.

  13. Impacts of Geomagnetic storms on the mid-latitude mesosphere and lower thermosphere observed by a Na lidar and TIMED/GUVI

    Science.gov (United States)

    Yuan, T.; Zhang, Y.

    2015-12-01

    In this paper, we report our findings on the correlation between the neutral temperature (around the mesopause) and thermospheric column density O/N2 ratio, along with their response to geomagnetic storms above mid-latitude of North America. A temperature/wind Doppler Na lidar, operating at Fort Collins, CO (41°N, 105°W) and later at Logan, UT (42°N and 112°W), observed significant temperature increases (temperature anomaly) above 95 km (as much as 55 K at 105 km altitude) during four geomagnetic storms (April 2002, Nov. 2004, May 2005 and Oct. 2012). Coincident TIMED/GUVI observations indicate significant depletion in the thermospheric O/N2 ratio at the lidar locations. These observations suggest that the local mesopause warming seen by the lidar is due to transport of the high-latitude Joule and particle heated neutrals at the E and F layers to the mid-latitude region.

  14. Investigating the effect of geomagnetic storm and equatorial electrojet on equatorial ionospheric irregularity over East African sector

    Science.gov (United States)

    Seba, Ephrem Beshir; Nigussie, Melessew

    2016-11-01

    The variability of the equatorial ionosphere is still a big challenge for ionospheric dependent radio wave technology users. To mitigate the effect of equatorial ionospheric irregularity on trans-ionospheric radio waves considerable efforts are being done to understand and model the equatorial electrodynamics and its connection to the creation of ionospheric irregularity. However, the effect of the East-African ionospheric electrodynamics on ionospheric irregularity is not yet well studied due to lack of multiple ground based instruments. But, as a result of International Heliophysical Year (IHY) initiative, which was launched in 2007, some facilities are being deployed in Africa since then. Therefore, recently deployed instruments, in the Ethiopian sector, such as SCINDA-GPS receiver (2.64°N dip angle) for TEC and amplitude scintillation index (S4) data and two magnetometers, which are deployed on and off the magnetic equator, data collected in the March equinoctial months of the years 2011, 2012, and 2015 have been used for this study in conjunction with geomagnetic storm data obtained from high resolution OMNI WEB data center. We have investigated the triggering and inhibition mechanisms for ionospheric irregularities using, scintillation index (S4), equatorial electrojet (EEJ), interplanetary electric field (IEFy), symH index, AE index and interplanetary magnetic field (IMF) Bz on five selected storm and two storm free days. We have found that when the eastward EEJ fluctuates in magnitude due to storm time induced electric fields at around noontime, the post-sunset scintillation is inhibited. All observed post-sunset scintillations in equinox season are resulted when the daytime EEJ is non fluctuating. The strength of noontime EEJ magnitude has shown direct relation with the strength of the post-sunset scintillations. This indicates that non-fluctuating EEJ stronger than 20 nT, can be precursor for the occurrence of the evening time ionospheric irregularities

  15. Comment on Decay of the Dst Field of Geomagnetic Disturbance After Substorm Onset and its Implication to Storm-Substorm Relation

    Science.gov (United States)

    Rostoker, G.; Baumjohann, W.; Gonzalez, W.; Kamide, Y.; Kokubun, S.; McPherron, R. L.; Tsurutani, B. T.

    1996-01-01

    Over the past few years, there has been a considerable revival in the study of geomagnetic storms stimulated by an increasing knowledge of the energetic particles which comprise the ring current. It is only in recent years that the composition of the ring current has been thouroughly explored and the important role of the oxygen component of the near Earth plasma sheet has become recognized.

  16. Study on the Geomagnetic Short Period Variations of the Northwestern Yunnan

    Science.gov (United States)

    Yuan, Y.; Li, Q.; Cai, J.

    2015-12-01

    The Northwestern Yunnan is located in the interaction area between the Eurasian plate and the India plate. This area has been the ideal place for the research of continental dynamics and the prediction for risk region of strong earthquake for its complex tectonic environment and frequent seismic activity. Therefore the study on the geomagnetic short period variations is of great significance in the exploration of deep electrical structure, analysis of the seismic origin and deep geodynamics in the Northwestern Yunnan of China . This paper is based on the geomagnetic data from the magnetometer array with 8 sites built in the northwestern Yunnan to explore the deep electrical structure by the method of geomagnetic depth sounding. Firstly, we selected a total of 183 geomagnetic short period events at the range of 6min to 120min period. And we found a north northwest dividing line, of which two sides has the opposite value in the vertical component variation amplitude, which indicates the obvious conductivity anomaly underground. Secondly, the contour maps of the ratio of vertical component and horizontal component variation amplitude ΔZ/ΔH in different periods reflects the changes of a high conductivity belt's direction and position. In addition, the induction arrows maps within the period of 2 - 256min also shows that on the two sides of the dividing line the induction vectors deviate from each other, and the amplitude and direction of vectors varies with periods regularly. In the light of this, we infer that a high conductivity belt probably exists, which stretches from the deep crust to uppermost mantle and changes with depth constantly with the reference of magnetotelluric sounding. In the end of this paper, the staggered grid finite difference method is used to model the simplified three-dimensional high conductivity anomaly, and the result shows magnetic field distributions are consistent with the observed geomagnetic short period variations characteristics in

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

    Science.gov (United States)

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

    2004-01-01

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

  18. Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations

    Science.gov (United States)

    Li, W.; Ma, Q.; Thorne, R. M.; Bortnik, J.; Zhang, X.-J.; Li, J.; Baker, D. N.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Blake, J. B.; Fennell, J. F.; Kanekal, S. G.; Angelopoulos, V.; Green, J. C.; Goldstein, J.

    2016-06-01

    Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3-D diffusion simulation. By quantitatively comparing the observed and simulated electron evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak location and produces characteristic flat-top pitch angle distributions. By only including radial diffusion, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons and potentially accelerates them to even higher energies. Moreover, plasmaspheric hiss is found to provide efficient pitch angle scattering losses for hundreds of keV electrons, while its scattering effect on > 1 MeV electrons is relatively slow. Although an additional loss process is required to fully explain the overestimated electron fluxes at multi-MeV, the combined physical processes of radial diffusion and pitch angle and energy diffusion by chorus and hiss reproduce the observed electron dynamics remarkably well, suggesting that quasi-linear diffusion theory is reasonable to evaluate radiation belt electron dynamics during this big storm.

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

    Science.gov (United States)

    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.

  20. Modeling of Ionosphere Effects of Geomagnetic Storm Sequence on September 9-14, 2005 in View of Solar Flares and Dependence of Model Input Parameters from AE-and Kp-indices

    Science.gov (United States)

    Klimenko, Maxim; Klimenko, Vladimir; Ratovsky, Konstantin; Goncharenko, Larisa

    Earlier by Klimenko et al., 2009 under carrying out the calculations of the ionospheric effects of storm sequence on September 9-14, 2005 the model input parameters (potential difference through polar caps, field-aligned currents of the second region and particle precipitation fluxes and energy) were set as function of Kp-index of geomagnetic activity. The analyses of obtained results show that the reasons of quantitative distinctions of calculation results and observations can be: the use of 3 hour Kp-index at the setting of time dependence of model input parameters; the dipole approach of geomagnetic field; the absence in model calculations the effects of the solar flares, which were taken place during the considered period. In the given study the model input parameters were set as function of AE-and Kp-indices of geomagnetic activity according to different empirical models and morphological representations Feshchenko and Maltsev, 2003; Cheng et al., 2008; Zhang and Paxton, 2008. At that, we taken into account the shift of field-aligned currents of the second region to the lower latitudes as by Sojka et al., 1994 and 30 min. time delay of variations of the field-aligned currents of second region relative to the variations of the potential difference through polar caps at the storm sudden commencement phase. Also we taken into account the ionospheric effects of solar flares. Calculation of ionospheric effects of storm sequence has been carried out with use of the Global Self-Consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) developed in WD IZMIRAN (Nam-galadze et al., 1988). We carried out the comparison of calculation results with experimental data. This study is supported by RFBR grant 08-05-00274. References Cheng Z.W., Shi J.K., Zhang T.L., Dunlop M. and Liu Z.X. Relationship between FAC at plasma sheet boundary layers and AE index during storms from August to October, 2001. Sci. China Ser. E-Tech. Sci., 2008, Vol. 51, No. 7, 842

  1. Geomagnetic secular variation in Sicily and revised ages of historic lavas from Mount Etna

    Science.gov (United States)

    Tanguy, J. C.; Bucur, I.; Thompson, J. F. C.

    1985-12-01

    The variation of geomagnetic field direction in Sicily during the past 700 yr has tentatively been determined using lavas of known date from Mount Etna1. Additional palaeomagnetic studies on several hundred volcanic samples, combined with archaeomagnetic investigations carried out on Norman buildings, have improved the previous results and permit a reconstruction of the geomagnetic variation curve to about AD 1000. This curve agrees well with those obtained for other European countries2-6 and may be used as a reference for checking the ages attributed to archaeological structures as well as volcanic products in southern Italy during the past 1,000 yr. The present results cast serious doubts on the true ages of numerous historically dated lavas from Mount Etna, most of which are at least several centuries older than previously believed. The conclusions have implications for the succession of eruptions, effusion rates, magmatic evolution, and so on, and demonstrate the inconsistency of eruptive models based on historical records alone.

  2. Dynamic Responses of the Earth's Outer Core to Assimilation of Observed Geomagnetic Secular Variation

    Science.gov (United States)

    Kuang, Weijia; Tangborn, Andrew

    2014-01-01

    Assimilation of surface geomagnetic observations and geodynamo models has advanced very quickly in recent years. However, compared to advanced data assimilation systems in meteorology, geomagnetic data assimilation (GDAS) is still in an early stage. Among many challenges ranging from data to models is the disparity between the short observation records and the long time scales of the core dynamics. To better utilize available observational information, we have made an effort in this study to directly assimilate the Gauss coefficients of both the core field and its secular variation (SV) obtained via global geomagnetic field modeling, aiming at understanding the dynamical responses of the core fluid to these additional observational constraints. Our studies show that the SV assimilation helps significantly to shorten the dynamo model spin-up process. The flow beneath the core-mantle boundary (CMB) responds significantly to the observed field and its SV. The strongest responses occur in the relatively small scale flow (of the degrees L is approx. 30 in spherical harmonic expansions). This part of the flow includes the axisymmetric toroidal flow (of order m = 0) and non-axisymmetric poloidal flow with m (is) greater than 5. These responses can be used to better understand the core flow and, in particular, to improve accuracies of predicting geomagnetic variability in future.

  3. Nighttime mesospheric hydroxyl enhancements during SEP events and accompanying geomagnetic storms: Ionization rate modeling and Aura satellite observations

    Science.gov (United States)

    Verkhoglyadova, O. P.; Wissing, J. M.; Wang, S.; Kallenrode, M.-B.; Zank, G. P.

    2016-07-01

    We quantify the effects of combined precipitating solar protons and magnetospheric electrons on nighttime odd hydrogen density enhancements during two solar energetic particle (SEP) events accompanied by strong geomagnetic storms. We perform detailed modeling of ionization rates for 7-17 November 2004 and 20-30 August 2005 intervals with improved version 1.6 of the Atmospheric Ionization Module Osnabrück model. Particle measurements from Geostationary Operational Environmental Satellites and Polar Orbiting Environmental Satellites are sorted and combined in 2 h intervals to create realistic particle precipitation maps that are used as the modeling input. We show that modeled atmospheric ionization rates and estimated peak odd hydrogen (primarily hydroxyl) production from 0.001 hPa to 0.1 hPa atmospheric pressure levels during these intervals are consistent with enhancements in nighttime averaged zonal odd hydrogen densities derived from newly reprocessed and improved data set of Microwave Limb Sounder instrument on board Aura satellite. We show that both precipitating SEPs and magnetospheric electrons contribute to mesospheric ionization and their relative contributions change throughout the intervals. Our event-based modeling results underline the importance of the combined ionization sources for odd hydrogen chemistry in the middle atmosphere.

  4. Bottom-up control of geomagnetic secular variation by the Earth's inner core.

    Science.gov (United States)

    Aubert, Julien; Finlay, Christopher C; Fournier, Alexandre

    2013-10-10

    Temporal changes in the Earth's magnetic field, known as geomagnetic secular variation, occur most prominently at low latitudes in the Atlantic hemisphere (that is, from -90 degrees east to 90 degrees east), whereas in the Pacific hemisphere there is comparatively little activity. This is a consequence of the geographical localization of intense, westward drifting, equatorial magnetic flux patches at the core surface. Despite successes in explaining the morphology of the geomagnetic field, numerical models of the geodynamo have so far failed to account systematically for this striking pattern of geomagnetic secular variation. Here we show that it can be reproduced provided that two mechanisms relying on the inner core are jointly considered. First, gravitational coupling aligns the inner core with the mantle, forcing the flow of liquid metal in the outer core into a giant, westward drifting, sheet-like gyre. The resulting shear concentrates azimuthal magnetic flux at low latitudes close to the core-mantle boundary, where it is expelled by core convection and subsequently transported westward. Second, differential inner-core growth, fastest below Indonesia, causes an asymmetric buoyancy release in the outer core which in turn distorts the gyre, forcing it to become eccentric, in agreement with recent core flow inversions. This bottom-up heterogeneous driving of core convection dominates top-down driving from mantle thermal heterogeneities, and localizes magnetic variations in a longitudinal sector centred beneath the Atlantic, where the eccentric gyre reaches the core surface. To match the observed pattern of geomagnetic secular variation, the solid material forming the inner core must now be in a state of differential growth rather than one of growth and melting induced by convective translation.

  5. How Different are the Ring Current Compositions and Strengths of the 20 November, 2003 and the 24 August, 2005 Geomagnetic Storms?

    Science.gov (United States)

    Brandt, P. C.; Mitchell, D. G.; Ohtani, S.

    2006-05-01

    The 20 November, 2003 and the 24 August, 2005 geomagnetic storms were both driven by an interplantery magnetic field (IMF) down to approximately -60 nT. Although, the minimum SYM-H (or Dst)depression on ground reached about -500 nT for the 20 November, 2003 storm, but not even -200 nT for the 24 August, 2005 storm. There can be several reasons for this outstanding difference: the meaning of the SYMH index and the relative tail-current contribution; the duration of the southward IMF was relatively short (~1 h) for the 24 August, 2005 storm. Did this imply less time for substorms to inject fresh plasma (especially O+) into the ring current?; Cold and dense plasmasheet. We discuss the composition and intensity of the global ring current during these two storms, by using energetic neutral atom (ENA) data from the Medium- and High Energy Neutral Atom (MENA and HENA) imagers onboard the IMAGE satellite. While at first glance the strength of the ENA images in the 10-200 keV hydrogen and oxygen are comparable for the two storms, we investigate indications that the <10 keV hydrogen data is slightly enhanced for the 20 November, 2003 storm. We will re analyze the HENA images (H and O) in more detail to retrieve the parent ion intensity and investigate the effect of substorms.

  6. Geomagnetic Secular Variation and Its Applications to the Core

    DEFF Research Database (Denmark)

    Jackson, Andrew; Finlay, Chris

    2015-01-01

    We review the observational constraints on the morphology and evolution of the magnetic field of the Earth over the last few centuries; these changes are referred to as the secular variation.Starting with a description of the available sources of original observations of the field, we thendiscuss...

  7. Geomagnetic Field Variations as Determined from Bulgarian Archaeomagnetic Data. Part II: The Last 8000 Years

    Science.gov (United States)

    Kovacheva, Mary; Jordanova, Neli; Karloukovski, Vassil

    The knowledge about past secular variations of the geomagnetic field is achieved on the basis of archaeomagnetic researches of which the Bulgarian studies form an extended data set. In Part I (Kovacheva and Toshkov, 1994), the methodology used in the Sofia palaeomagnetic laboratory was described and the secular variation curves for the last 2000 years were shown. In Part II (this paper), the basic characteristics of the prehistoric materials used in the archaeomagnetic studies are emphasised, particularly in the context of the rock magnetic studies used in connection with palaeointensity determinations. The results of magnetic anisotropy studies of the prehistoric ovens and other fired structures are summarised, including the anisotropy correction of the palaeointensity results for prehistoric materials, different from bricks and pottery. Curves of the direction and intensity of the geomagnetic field during the last 8000 years in Bulgaria are given. The available directional and intensity values have been used to calculate the variation curve of the virtual dipole moment (VDM) for the last 8000 years based on different time interval averages. The path of virtual geomagnetic pole (VGP) positions is discussed.

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

    Directory of Open Access Journals (Sweden)

    G. Duma

    2003-01-01

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

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

    Science.gov (United States)

    Kubicka, M.; Möstl, C.; Amerstorfer, T.; Boakes, P. D.; Feng, L.; Eastwood, J. P.; Törmänen, O.

    2016-12-01

    Prediction of the effects of coronal mass ejections (CMEs) on Earth strongly depends on knowledge of the interplanetary magnetic field southward component, B z . Predicting the strength and duration of B z inside a CME with sufficient accuracy is currently impossible, forming the so-called B z problem. Here, we provide a proof-of-concept of a new method for predicting the CME arrival time, speed, B z , and resulting disturbance storm time (Dst) index on Earth based only on magnetic field data, measured in situ in the inner heliosphere (vector magnetic field data from a spacecraft at an artificial Lagrange point between the Sun and Earth or to data taken by any spacecraft temporarily crossing the Sun-Earth line.

  10. Storm time variation of radiative cooling of thermosphere by nitric oxide emission

    Science.gov (United States)

    Krishna, M. V. Sunil; Bag, Tikemani; Bharti, Gaurav

    2016-07-01

    The fundamental vibration-rotation band emission (Δν=1, Δ j=0,± 1) by nitric oxide (NO) at 5.3 µm is one of the most important cooling mechanisms in thermosphere. The collisional vibrational excitation of NO(ν=0) by impact with atomic oxygen is the main source of vibrationally excited nitric oxide. The variation of NO density depends on latitude, longitude and season. The present study aims to understand how the radiative flux gets influenced by the severe geomagnetic storm conditions. The variation of Nitric Oxide (NO) radiative flux exiting thermosphere is studied during the superstorm event of 7-12 November, 2004. The observations of TIMED/SABER suggest a strong anti-correlation with the O/N_2 ratio observed by GUVI during the same period. On a global scale the NO radiative flux showed an enhancement during the main phase on 8 November, 2004, whereas maximum depletion in O/N_2 is observed on 10 November, 2004. Both O/N_2 and NO radiative flux were found to propagate equatorward due to the effect of meridional wind resulting from joule and particle heating in polar region. Larger penetrations is observed in western longitude sectors. These observed variations are effectively connected to the variations in neutral densities. In the equatorial sectors, O/N_2 shows enhancement but almost no variation in radiative flux is observed. The possible reasons for the observed variations in NO radiative emission and O/N_2 ratios are discussed in the light of equator ward increase in the densities and prompt penetration.

  11. Geomagnetic intensity variations over the past 780 kyr obtained from near-seafloor magnetic anomalies.

    Science.gov (United States)

    Gee, J S; Cande, S C; Hildebrand, J A; Donnelly, K; Parker, R L

    2000-12-14

    Knowledge of past variations in the intensity of the Earth's magnetic field provides an important constraint on models of the geodynamo. A record of absolute palaeointensity for the past 50 kyr has been compiled from archaeomagnetic and volcanic materials, and relative palaeointensities over the past 800 kyr have been obtained from sedimentary sequences. But a long-term record of geomagnetic intensity should also be carried by the thermoremanence of the oceanic crust Here we show that near-seafloor magnetic anomalies recorded over the southern East Pacific Rise are well correlated with independent estimates of geomagnetic intensity during the past 780 kyr. Moreover, the pattern of absolute palaeointensity of seafloor glass samples from the same area agrees with the well-documented dipole intensity pattern for the past 50 kyr. A comparison of palaeointensities derived from seafloor glass samples with global intensity variations thus allows us to estimate the ages of surficial lava flows in this region. The record of geomagnetic intensity preserved in the oceanic crust should provide a higher-time-resolution record of crustal accretion processes at mid-ocean ridges than has previously been obtainable.

  12. Bottom-up control of geomagnetic secular variation by the Earth's inner core

    DEFF Research Database (Denmark)

    Aubert, Julien; Finlay, Chris; Fournier, Alexandre

    2013-01-01

    Temporal changes in the Earth’s magnetic field, known as geomagnetic secular variation, occur most prominently at low latitudes in the Atlantic hemisphere1, 2 (that is, from −90 degrees east to 90 degrees east), whereas in the Pacific hemisphere there is comparatively little activity. This is a c......Temporal changes in the Earth’s magnetic field, known as geomagnetic secular variation, occur most prominently at low latitudes in the Atlantic hemisphere1, 2 (that is, from −90 degrees east to 90 degrees east), whereas in the Pacific hemisphere there is comparatively little activity....... This is a consequence of the geographical localization of intense, westward drifting, equatorial magnetic flux patches at the core surface3. Despite successes in explaining the morphology of the geomagnetic field4, numerical models of the geodynamo have so far failed to account systematically for this striking pattern......-like gyre6. The resulting shear concentrates azimuthal magnetic flux at low latitudes close to the core–mantle boundary, where it is expelled by core convection and subsequently transported westward. Second, differential inner-core growth7, 8, fastest below Indonesia6, 9, causes an asymmetric buoyancy...

  13. Geomagnetic secular variations of high-latitude glaciomarine sediments: data from the Kola Peninsula, northwestern Russia

    Science.gov (United States)

    Bakhmutov, V.; Yevzerov, V.; Kolka, V.

    1994-08-01

    Geological, radiocarbon and paleomagnetic investigations of paleobays were carried out in the northwestern part of the Kola Peninsula (the Pechenga and Shuonijoki river valleys). The period from 10.3 to 9.5 kyear ago was characterized by the accumulation of glaciomarine sediments while the period 8.6-9.5 kyear was characterized by marine ones. Ca. 8.6 kyear marks the beginning of the formation of marine sediment transgression series. The clay sequences, accumulated in paleobays during a few hundred years, are an important object for studying the ancient geomagnetic field secular variations at high latitudes. Paleomagnetic signals in three outcrops from Pechenga river valley (69.5°N) record high-latitudinal inclination and declination variations in the time interval 8.5-10.0 kyear ago which correlate well with the secular variations of Early Holocene lacustrine deposits in the northern part of Ladoga Lake (61.5°N). A characteristic feature of the paleosecular variations at high latitudes is the proximity VGP to the observation point. Near to vertical inclination with declination variation amplitudes up to 150 took place ca. 9700-9500 year ago. The geomagnetic pole drifted south or crossed the Kola Peninsula at that time. The inclination and declination variations may be used in correlating the Early Holocene marine and lacustrine deposits in adjacent regions.

  14. Solar Flares and Variation of Local Geomagnetic Field: Measurements by the Huancayo Observatory over 2001-2010

    Science.gov (United States)

    Carlos Reyes, Rafael E.; Gárate Ayesta, Gabriel A.; Reyes Navarro, Felipe A.

    2017-02-01

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

  15. Reliability of geomagnetic secular variations recorded in a loess section at Lingtai,north-central China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An investigation of the rock magnetic properties using stepwise isothermal remanence (IRM) acquisition,thermomagnetic analysis and temperature-dependent susceptibility history,identifies magnetite as the carrier of the main fraction of the remanence,associated with maghemite and hematite in Malan loess (L1),Holocene soil (S0) and last-glacial paleosol (S1).The presence of short-lived direction fluctuations indicates that no significant smoothing occurs in L1 when its remanence is locked,and thus L1 is capable of recording the geomagnetic secular variation (PSV),while the PSV has been severely smoothed or wiped out by pedogenic processes during S1 formation.It has been suggested that the Mono Lake and Laschamp excursions are two independent geomagnetic events based on this study.

  16. Reliability of geomagnetic secular variations recorded in a loess section at Lingtai, north-central China

    Institute of Scientific and Technical Information of China (English)

    朱日祥; 郭斌; 潘永信; 刘青松; A.Zeman; V.Suchy

    2000-01-01

    An investigation of the rock magnetic properties using stepwise isothermal remanence (IRM) acquisition, thermomagnetic analysis and temperature-dependent susceptibility history, identifies magnetite as the carrier of the main fraction of the remanence, associated with maghemite and hematite in Malan loess (L1), Holocene soil (SO) and last-glacial paleosol (S1). The presence of short-lived direction fluctuations indicates that no significant smoothing occurs in L1 when its remanence is locked, and thus L1 is capable of recording the geomagnetic secular variation (PSV), while the PSV has been severely smoothed or wiped out by pedogenic processes during S1 formation. It has been suggested that the Mono Lake and Laschamp excursions are two independent geomagnetic events based on this study.

  17. On the periodic variations of secondary cosmic rays and the geomagnetic Pc4 pulsations in BMAr

    Directory of Open Access Journals (Sweden)

    I. M. Martin

    Full Text Available In a set of balloon flights in the Brazilian magnetic anomaly region (BMAr short time periodic variations were observed, i.e. pulsation, of secondary charged and neutral particle fluxes, X- and -ray fluxes with amplitudes of about 2–4%. The pulsations are accompanied by the geomagnetic Pc4 pulsations and have similar periodicity. The phenomenon was observed over various local times and in quiet and disturbed magnetospheric conditions. One of the explanations of this effect, i.e. periodic variation of local cut-off rigidity, and following pulsations of primary and secondary cosmic ray intensity is suggested.

  18. Multispacecraft observations and modeling of the 22/23 June 2015 geomagnetic storm

    Science.gov (United States)

    Reiff, P. H.; Daou, A. G.; Sazykin, S. Y.; Nakamura, R.; Hairston, M. R.; Coffey, V.; Chandler, M. O.; Anderson, B. J.; Russell, C. T.; Welling, D.; Fuselier, S. A.; Genestreti, K. J.

    2016-07-01

    The magnetic storm of 22-23 June 2015 was one of the largest in the current solar cycle. We present in situ observations from the Magnetospheric Multiscale Mission (MMS) and the Van Allen Probes (VAP) in the magnetotail, field-aligned currents from AMPERE (Active Magnetosphere and Planetary Electrodynamics Response), and ionospheric flow data from Defense Meteorological Satellite Program (DMSP). Our real-time space weather alert system sent out a "red alert," correctly predicting Kp indices greater than 8. We show strong outflow of ionospheric oxygen, dipolarizations in the MMS magnetometer data, and dropouts in the particle fluxes seen by the MMS Fast Plasma Instrument suite. At ionospheric altitudes, the AMPERE data show highly variable currents exceeding 20 MA. We present numerical simulations with the Block Adaptive Tree-Solarwind - Roe - Upwind Scheme (BATS-R-US) global magnetohydrodynamic model linked with the Rice Convection Model. The model predicted the magnitude of the dipolarizations, and varying polar cap convection patterns, which were confirmed by DMSP measurements.

  19. Seasonal effect on the diurnal variation of the geomagnetic field registered in Huancayo Observatory

    CERN Document Server

    Rosales, Domingo

    2016-01-01

    In this article we study the seasonal effect on the diurnal variation of the geomagnetic field registered in the Huancayo Observatory, located in the Magnetic Equator, which is driven by "ionospheric currents" and its counterpart induced by "telluric currents". Huancayo Observatory has the highest amplitude in the diurnal variation, because of being in the Magnetic Equator and under the "Equatorial Electrojet". We present the pattern of seasonal variation in diurnal variation of components X, Y and Z, the same as confirmed by previous works since 1940. The effect of solar activity cycle of about 11 years in the diurnal variation is also confirmed; it is observed that amplitudes are greater in the maximum of solar activity.

  20. "Double low-points" anomaly in daily variation of vertical component of geomagnetic field before the MS8.0 Wenchuan earthquake

    Institute of Scientific and Technical Information of China (English)

    Jiuchang Hu; Wei Liu; Minrui Guo; Hua Zheng

    2009-01-01

    The "double low-points" anomaly in daily variation of vertical geomagnetic component was observed on May 9, 2008 at 13 geomagnetic observatories belonging to the geomagnetic observatory network center of China Earthquake Administration. These observatories distribute roughly on three belts with the intersection in western Sichuan. On May 12, three days after the anomaly appearance, the great MS8.0 Wenchuan earthquake occurred. The "double low-points" anomaly in daily variation of vertical geomagnetic component is an anomalous phenomenon of regional geomagnetism, which does exist objectively. The possible cause is the change of extrinsic eddy current system resulting in geomagnetic daily quiet variation (Sq), or the delay of several hours between the intrinsic and the extrinsic eddy current systems. The relationship between the "double low-points" anomaly of daily geomagnetic variation and the earthquake reveals that the former possibly reflects the accelera-tive alteration of earthquake gestation in the deep Earth.

  1. A model of the geomagnetic field and its secular variation for epoch 2000 estimated from Orsted data

    DEFF Research Database (Denmark)

    Olsen, Nils

    2002-01-01

    The availability of high-precision geomagnetic measurements from satellites such as Orsted and CHAMP opens a new era in geomagnetic field research. However, in order to take full advantage of the improved data accuracy it is necessary to refine the usual way of deriving field models from satellite...... as measured simultaneously by globally distributed geomagnetic observatories. In addition, the observatory data are used to constrain secular variation. The model is estimated using an iteratively reweighted least-squares method with Huber weights to account for the non-Gaussian data error distribution...

  2. Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet (Sq) daily variation

    Science.gov (United States)

    Shinbori, A.; Koyama, Y.; Yatagai, A. I.; Nose, M.; Hori, T.; Otsuka, Y.

    2012-12-01

    It has been well-known that geomagnetic solar quiet (Sq) daily variation is produced by the global ionospheric currents flowing in the E-region, which are generated by dynamo process via interaction between the neutral wind and ionospheric plasma in a region of the lower thermosphere and ionosphere. Then, to investigate the Sq amplitude is essential for understanding the long-term variations in the ionospheric conductivity and neutral wind of the lower thermosphere and ionosphere. Recently, Elias et al. [2010] reported that the Sq amplitude tends to increase by 5.4-9.9 % in the middle latitudes in a period of 1961-2001. They mentioned that the long-term variation of ionospheric conductivity associated with geomagnetic secular variation mainly determines the Sq trend, but that the rest component is due to ionospheric conductivity enhancement associated with cooling effect in the thermosphere due to increasing greenhouse gas. In the present study, we clarify the characteristics of the long-term variation in the Sq amplitude using the long-term observation data of geomagnetic field and neutral wind. In the present analysis, we used the F10.7 solar flux as a good indicator of the variation in the solar irradiance in the EUV and UV range as well as geomagnetic field data with time resolution of 1 hour observed at 184 geomagnetic stations. The definition of the Sq amplitude is the difference of the H-component between the maximum and minimum every day when the Kp index is less than 4. As a result, the long-term variation in the Sq amplitude at all the geomagnetic stations shows a strong correlation with the solar F10.7 flux which depends on 11-year solar activity. The relationship between the Sq amplitude and F10.7 flux was not linear but nonlinear. This nonlinearity could be interpreted as the decrease of production rate of electrons and ions in the ionosphere for the strong EUV and UV fluxes as already reported by Balan et al. [1993]. In order to minimize the solar

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

    Science.gov (United States)

    Biktash, Lilia

    2016-07-01

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

  4. Geomagnetic Secular Variation in Texas over the Last 17,000 Years: High-Intensity Geomagnetic Field 'Spike' Observed at ca. 3000 cal BP

    Science.gov (United States)

    Bourne, M. D.; Feinberg, J. M.; Waters, M. R.; Stafford, T. W., Jr.; Forman, S. L.; Lundelius, E. L.

    2015-12-01

    By observing the fluctuations in direction and intensity of the Earth's magnetic field through time, we increase our understanding of the fluid motions in the Earth's outer core that sustain the geomagnetic field, the geodynamo. Recent archaeomagnetic studies in the Near East have proposed extremely rapid increases - 'spikes' - in geomagnetic field intensity ca. 3000 years ago that have proved problematic for our current understanding of core-flow. However, until now, these geomagnetic spikes had not been observed outside of the Near East, where they have been found in metallurgical slag and mud brick walls. We present a new fully-oriented, geomagnetic secular variation and relative palaeointensity (RPI) record for the last 17,000 years from Hall's Cave, Texas. Sediment washed into the cave has formed a continuous stratigraphic sequence that is at least 3.5 m thick. Within the stable, cool climate of the cave, pedogenic and bioturbation processes are almost non-existent, thereby limiting post-depositional physical and geochemical alteration of the magnetic record. The sub-aerial and subterranean setting of the sedimentary sequence in Hall's Cave enabled us to collect oriented palaeomagnetic cubes from an excavated section through the sequence. The palaeomagnetic samples yielded high-quality vectors. An age model for the sequence, determined using 57 AMS 14C-dates on individual bones from microvertebrate, was combined with the palaeomagnetic data to construct a secular variation record. The record is in broad agreement with predictions by Holocene field models for the site's location. However, at ca. 3000 years ago, the RPI data indicate an almost four-fold increase in geomagnetic field intensity lasting several hundred years and contemporaneous with the more short-lived, decadal-scale spikes reported from the Near East. Evidence for this extreme intensity event outside of the Near East has major implications for our current understanding of core-dynamics.

  5. Forward and adjoint quasi-geostrophic models of the geomagnetic secular variation

    CERN Document Server

    Canet, Elisabeth; Jault, Dominique

    2010-01-01

    We introduce a quasi-geostrophic model of core dynamics, which aims at describ- ing core processes on geomagnetic secular variation timescales. It extends the for- malism of Alfv ?en torsional oscillations by incorporating non-zonal motions. Within this framework, the magnetohydrodynamics takes place in the equatorial plane; it involves quadratic magnetic quantities, which are averaged along the direction of ro- tation of the Earth. In addition, the equatorial flow is projected on the core-mantle boundary. It interacts with the magnetic field at the core surface, through the radial component of the magnetic induction equation. That part of the model connects the dynamics and the observed secular variation, with the radial component of the magnetic field acting as a passive tracer. We resort to variational data assimilation to construct formally the relationship between model predictions and observations. Variational data assimilation seeks to minimize an objective function, by computing its sensitivity to its...

  6. Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

    Science.gov (United States)

    Yamazaki, Y.; Maute, A.

    2017-03-01

    A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μ A/m2 flowing on the sunlit side of the E-region ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the non-specialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

  7. Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

    Science.gov (United States)

    Yamazaki, Y.; Maute, A.

    2016-09-01

    A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μA/m2 flowing on the sunlit side of the E-region ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the non-specialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

  8. New Insights on Long Term Geomagnetic Moment Variation from Cosmogenic Nuclide and Paleointensity Signatures along Ocean Sediment Cores.

    Science.gov (United States)

    Thouveny, N.; Bourles, D. L.; Valet, J. P.; Bassinot, F. C.; Ménabréaz, L.; Simon, Q.; Demory, F.; Valery, G.; Vidal, L.; Beaufort, L.; de Garidel-Thoron, T.

    2015-12-01

    Some numerical and experimental simulations suggest that precession might supply enough power to influence planetary dynamos. The demonstration of a causal relationship between the Earth's orbital motion and variations of the geomagnetic field intensity, would open interesting perspective for modelling the past and future geomagnetic field behaviour and its eventual relationships to past and future orbitally constrained, climatic changes. Although pristine geomagnetic signals can be extracted by filtering and stacking multiple normalized intensity records, the reconstruction of high resolution geomagnetic field variations still raises questions. Namely, significant variance at orbital frequencies in relative paleointensity (RPI) records are generally considered as clues of residual contamination by paleoclimatically induced variations of magnetic carriers size ranges or mineralogy. Such questions can be adressed using other indicators of the geomagnetic dipole moment variation, such as the cosmogenic production modulated by the magnetospheric shielding. During the MAGORB project (ANR-09-BLAN-053-001) cosmogenic nuclide geochemistry, d18O, and paleomagnetic records were constructed along thick clayey-carbonate sequences deposited in the equatorial pacific and indian oceans over the last million of years. Authigenic 10Be/9Be ratio and RPI variations generally exhibit similar ranges of oscillations. However significant offsets appear between some RPI lows and their corresponding 10Be/9Be peaks, suggesting delayed lock-in of the remanent magnetization. After transfer on time scales the new geomagnetic moment series can be compared with the PISO-1500 and SINT-2000 stacks, and with the 10Be ice core record of EPICA Dome C. These new authigenic 10Be/9Be ratio records provide new opportunities to: 1) assess the validity of high resolution RPI records, 2) evaluate address the question of the presence of orbital periods in the paleo-field geomagnetic spectrum, and 3) to

  9. Study of the effect of 17-18 March 2015 geomagnetic storm on the Indian longitudes using GPS and C/NOFS

    Science.gov (United States)

    Ray, Sarbani; Roy, Bidyut; Paul, Krishnendu Sekhar; Goswami, Samiddha; Oikonomou, Christina; Haralambous, Haris; Chandel, Babita; Paul, Ashik

    2017-02-01

    The largest geomagnetic storm in solar cycle 24 occurred during 17-18 March 2015 where the main phase of the storm commenced from 07:00 UT of 17 March 2015 and reached the Dst negative minimum at 22:00 UT. The present paper reports observations of total electron content (TEC), amplitude, and phase scintillations from different GPS stations of India during the storm of 17 March and highlights its effects on GPS. It also presents the global equatorial spread F (ESF) occurrence during the storm using total ion density drift measurements from Communication and Navigation Outage Forecast System (C/NOFS) satellite. TEC enhancements were noted from stations along 77°E meridian around 10:00 UT on 17 March compared to 16 and 18 March indicating positive storm effects arising out of equatorward neutral wind in the local morning to noon sector of the main phase. Intense scintillation observations from Calcutta were most extensive during 15:00-16:00 UT, 17 March, and the receiver recorded a longitude deviation of 5.2 m during this time. Cycle slips of the order of 8 s could be observed during periods of intense phase scintillations on the same night. Intense scintillation observation from Palampur is an exceptional phenomenon attributed to the dramatic enhancement of the electric field due to prompt penetrating (undershielded) electric leading to a very high upward ion velocity over the magnetic equator as recorded by C/NOFS. The total ion density measured globally by C/NOFS reveals two distinct longitude regions of ESF occurrence during the storm: (i) East Pacific sector and (ii) Indian longitude during the storm. The time and longitude of ESF occurrence could be predicted using the time of southward turning of interplanetary magnetic field Bz.

  10. Preliminary study on the source field mode of geomagnetic six-month-period variations

    Institute of Scientific and Technical Information of China (English)

    陈伯舫; 冯戬云

    1997-01-01

    The monthly means of north component X of geomagnetic field from 16 observatories during 1984-1988 were analyzed using the Sompi spectral analysis technique. Most of these observatories are located in China. The analysis of the semiannual variations indicates that the latitude has no apparent effect on the X component. This clearly implies that the source field mode of semiannual variations cannot simply be described by using the P°1 mode. Using the P°1 mode to estimate the inductive scale length C in the semiannual period, the value of C at each observatory would be biased significantly. The purpose of this study is to find which kind of modes is optimal for estimating the values of C corresponding to the semiannual variations. The results show that a composite mode, involving five terms P°n(n = 1,....,5), might be a reasonable and acceptable one.

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

    Indian Academy of Sciences (India)

    N Jeni Victor; C Panneerselvam; C P Anil Kumar

    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.

  12. Multidimensional scaling technique for analysis of magnetic storms at Indian observatories

    Indian Academy of Sciences (India)

    M Sridharan; A M S Ramasamy

    2002-12-01

    Multidimensional scaling is a powerful technique for analysis of data. The latitudinal dependenceof geomagnetic field variation in horizontal component (H) during magnetic storms is analysed in this paper by employing this technique.

  13. Solar and Interplanetary Sources of Major Geomagnetic Storms (Dst less than or equal to -100 nT) During 1996 - 2005

    Science.gov (United States)

    Zhang, J.; Richardson, I.; Webb, D. F.; Gopalswamy, N.; Huttunen, E.; Kasper, J.; Nitta, N.; Poomvises, W.; Thompson, B. J.; Wu, C.-C.; Yashiro, S.; Zhukov, A.

    2007-01-01

    We present the results of an investigation of the sequence of events from the Sun to the Earth that ultimately led to the 88 major geomagnetic storms (defined by minimum Dst less than or equal to -100 nT) that occurred during 1996 - 2005. The results are achieved through cooperative efforts that originated at the Living with a Star (LWS) Coordinated Data- Analysis Workshop (CDAW) held at George Mason University in March 2005. Based on careful examination of the complete array of solar and in-situ solar wind observations, we have identified and characterized, for each major geomagnetic storm, the overall solar-interplanetary (solar-IP) source type, the time, velocity and angular width of the source coronal mass ejection (CME), the type and heliographic location of the solar source region, the structure of the transient solar wind flow with the storm-driving component specified, the arrival time of shock/disturbance, and the start and ending times of the corresponding IP CME (ICME). The storm-driving component, which possesses a prolonged and enhanced southward magnetic field (B(sub s)) may be an ICME, the sheath of shocked plasma (SH) upstream of an ICME, a corotating interaction region (CIR), or a combination of these structures. We classify the Solar-IP sources into three broad types: (1) S-type, in which the storm is associated with a single ICME and a single CME at the Sun; (2) M-type, in which the storm is associated with a complex solar wind flow produced by multiple interacting ICMEs arising from multiple halo CMEs launched from the Sun in a short period; (3) C-type, in which the storm is associated with a CIR formed at the leading edge of a high speed stream originating from a solar coronal hole (CH). For the 88 major storms, the S-type, M-type and C-type events number 53 (60%): 24 (27%) and 11 (13%), respectively. For the 85 events for which the surface source regions could be investigated, 54 (63%) of the storms originated in solar active regions, 10 (12

  14. Long-term variations in the flux of cosmogenic isotope 10Be over the last 10000 years: Variations in the geomagnetic field and climate

    Science.gov (United States)

    Vasiliev, S. S.; Dergachev, V. A.; Raspopov, O. M.; Jungner, H.

    2012-02-01

    A spectral analysis of data on the flux of cosmogenic 10Be in ice core samples from the Central Greenland (project GRIP) over the last 10 thousand years have been carried out. It has been shown that the 10Be flux varies cyclically; the most significant cycle is of about 2300 years. Variations in the position of the virtual geomagnetic pole over 8000 years have been analyzed. Significant components, pointing to the cyclic variation in the position of the geomagnetic pole with a period of about 2300 years, have been revealed in a periodogram of the virtual geomagnetic pole longitude. In addition to the nearly 2300-year-long cycle, some lines are observable in the 10Be flux periodogram, which can be considered as a manifestation of the 1000-year-long cycle of the 10Be deposition rate on the ice surface. The relationship between the cyclicity of the geomagnetic pole position and the 10Be flux is discussed.

  15. A case for variational geomagnetic data assimilation: insights from a one-dimensional, nonlinear, and sparsely observed MHD system

    CERN Document Server

    Fournier, Alexandre; Alboussière, Thierry

    2007-01-01

    Secular variations of the geomagnetic field have been measured with a continuously improving accuracy during the last few hundred years, culminating nowadays with satellite data. It is however well known that the dynamics of the magnetic field is linked to that of the velocity field in the core and any attempt to model secular variations will involve a coupled dynamical system for magnetic field and core velocity. Unfortunately, there is no direct observation of the velocity. Independently of the exact nature of the above-mentioned coupled system -- some version being currently under construction -- the question is debated in this paper whether good knowledge of the magnetic field can be translated into good knowledge of core dynamics. Furthermore, what will be the impact of the most recent and precise geomagnetic data on our knowledge of the geomagnetic field of the past and future? These questions are cast into the language of variational data assimilation, while the dynamical system considered in this pape...

  16. Marine sediments and Beryllium-10 record of the geomagnetic moment variations during the Brunhes period.

    Science.gov (United States)

    Ménabréaz, Lucie; Thouveny, Nicolas; Bourlès, Didier; Demory, François

    2010-05-01

    Over millennial time scales, the atmospheric production of the cosmonuclid 10Be (half-life 1.387 ± 0.012 Ma [Shmeleff et al., 2009; Korschinek et al., 2009]) is modulated by the geomagnetic field strength, following a negative power law (e.g. Lal, 1988; Masarik and Beer, 2009). With respect to paleomagnetic reconstructions, 10Be-derived paleointensity records can therefore constitute an alternative, global and independent reading of the dipole moment variations. During the last years, efforts have been made to extract a geomagnetic signal from single and stacked 10Be records in natural archives such as ice and marine sediments (e.g. Carcaillet et al., 2004; Christl et al., 2007; Muscheler et al., 2005). In marine sediments, the 10Be concentration results from complex interplay of several processes: cosmogenic production, adsorption on sediment particles, redistribution by fluviatile and oceanic transport, and deposition. Therefore, a correction procedure is required to consider both sediment redistribution and enhanced scavenging, which can alter the primary signatures. To reconstruct the succession of field intensity lows accompanying excursions during the Brunhes chron, we investigated authigenic 10Be/9Be record of marine sequences also studied for paleomagnetism and oxygen isotopes. Mid and low latitude sites were preferred in order to benefit from the most efficient modulation by the magnetospheric shielding. We present a high resolution authigenic 10Be/9Be record of the last 50 ka recovered from the Portuguese Margin, that deciphers the cosmonuclide 10Be overproduction created by the geomagnetic dipole low associated with the Laschamp excursion. This record is compared to other proxy records of the geomagnetic field variations for the same time interval: (1) the relative paleointensity (RPI) reconstructed from the same sediments and the GLOPIS-75 record (Laj et al., 2004), (2) the absolute VDM record based on absolute paleointensities measured on lava flows

  17. Use of spherical elementary currents to map the polar current systems associated with the geomagnetic sudden commencements on 2013 and 2015 St. Patrick's Day storms

    Science.gov (United States)

    Marsal, S.; Torta, J. M.; Segarra, A.; Araki, T.

    2017-01-01

    Araki's model of geomagnetic sudden commencements (SCs) establishes that the ground magnetic signatures globally observed after the onset produced by an increased solar wind dynamic pressure impacting on the Earth's magnetosphere are caused by the setting up of a system of electric currents in the coupled magnetosphere-ionosphere. This current system consists of a particular evolving set of magnetopause currents closing in the ionosphere through geomagnetic field-aligned currents (FACs) and their induced counterpart. The present paper confirms the starting assumptions of the referred model by use of spherical elementary current systems (SECS), namely, the existence of FACs reversing polarity during the first couple of minutes of the SC. It is the first time that SECS have been applied to the study of SCs. The method has been fed with data from more than 100 stations of the global network of geomagnetic observatories and variometer sites in the northern hemisphere so as to provide a reliable pattern of the equivalent current system flowing at ionospheric heights on the occasion of the SCs associated with the 2013 and 2015 St. Patrick's Day storms. The combined analysis of solar wind data and the synoptic view of the SC current patterns provided by SECS allows it to explain some of the differences observed between both events.

  18. Impacts of CME-induced geomagnetic storms on the midlatitude mesosphere and lower thermosphere observed by a sodium lidar and TIMED/GUVI

    Science.gov (United States)

    Yuan, T.; Zhang, Y.; Cai, X.; She, C.-Y.; Paxton, L. J.

    2015-09-01

    In this paper, we report our findings on the correlation between the neutral temperature (around the mesopause) and thermospheric column density O/N2 ratio, along with their response to geomagnetic storms above midlatitude of North America. A temperature/wind Doppler Na lidar, operating at Fort Collins, CO (41°N, 105°W), and later at Logan, UT (42°N and 112°W), observed significant temperature increases (temperature anomaly) above 95 km (as much as 55 K at 105 km altitude) during four coronal mass ejection-induced geomagnetic storms (April 2002, November 2004, May 2005, and October 2012). Coincident Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Global Ultraviolet Spectrographic Imager observations indicate significant depletion in the thermospheric O/N2 ratio at the lidar locations. These observations suggest that the local mesopause warming seen by the lidar is due to transport of the high-latitude joule and particle heated neutrals at the E and F layers to the midlatitude region.

  19. Sun-to-Earth Characteristics of Two Coronal Mass Ejections Interacting near 1 AU: Formation of a Complex Ejecta and Generation of a Two-Step Geomagnetic Storm

    CERN Document Server

    Liu, Ying D; Wang, Rui; Luhmann, Janet G; Richardson, John D; Lugaz, Noé

    2014-01-01

    On 2012 September 30 - October 1 the Earth underwent a two-step geomagnetic storm. We examine the Sun-to-Earth characteristics of the coronal mass ejections (CMEs) responsible for the geomagnetic storm with combined heliospheric imaging and in situ observations. The first CME, which occurred on 2012 September 25, is a slow event and shows an acceleration followed by a nearly invariant speed in the whole Sun-Earth space. The second event, launched from the Sun on 2012 September 27, exhibits a quick acceleration, then a rapid deceleration and finally a nearly constant speed, a typical Sun-to-Earth propagation profile for fast CMEs \\citep{liu13}. These two CMEs interacted near 1 AU as predicted by the heliospheric imaging observations and formed a complex ejecta observed at Wind, with a shock inside that enhanced the pre-existing southward magnetic field. Reconstruction of the complex ejecta with the in situ data indicates an overall left-handed flux rope-like configuration, with an embedded concave-outward shoc...

  20. SUN-TO-EARTH CHARACTERISTICS OF TWO CORONAL MASS EJECTIONS INTERACTING NEAR 1 AU: FORMATION OF A COMPLEX EJECTA AND GENERATION OF A TWO-STEP GEOMAGNETIC STORM

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying D.; Yang, Zhongwei; Wang, Rui [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Luhmann, Janet G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Richardson, John D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Lugaz, Noé, E-mail: liuxying@spaceweather.ac.cn [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)

    2014-10-01

    On 2012 September 30-October 1 the Earth underwent a two-step geomagnetic storm. We examine the Sun-to-Earth characteristics of the coronal mass ejections (CMEs) responsible for the geomagnetic storm with combined heliospheric imaging and in situ observations. The first CME, which occurred on 2012 September 25, is a slow event and shows an acceleration followed by a nearly invariant speed in the whole Sun-Earth space. The second event, launched from the Sun on 2012 September 27, exhibits a quick acceleration, then a rapid deceleration, and finally a nearly constant speed, a typical Sun-to-Earth propagation profile for fast CMEs. These two CMEs interacted near 1 AU as predicted by the heliospheric imaging observations and formed a complex ejecta observed at Wind, with a shock inside that enhanced the pre-existing southward magnetic field. Reconstruction of the complex ejecta with the in situ data indicates an overall left-handed flux-rope-like configuration with an embedded concave-outward shock front, a maximum magnetic field strength deviating from the flux rope axis, and convex-outward field lines ahead of the shock. While the reconstruction results are consistent with the picture of CME-CME interactions, a magnetic cloud-like structure without clear signs of CME interactions is anticipated when the merging process is finished.

  1. Forward and adjoint quasi-geostrophic models of the geomagnetic secular variation

    Science.gov (United States)

    Canet, Elisabeth; Fournier, Alexandre; Jault, Dominique

    2009-11-01

    We introduce a quasi-geostrophic model of core dynamics, which aims at describing core processes on geomagnetic secular variation timescales. It extends the formalism of Alfvén torsional oscillations by incorporating nonzonal motions. Within this framework, the magnetohydrodynamics takes place in the equatorial plane; it involves quadratic magnetic quantities, which are averaged along the direction of rotation of the Earth. In addition, the equatorial flow is projected on the core-mantle boundary. It interacts with the magnetic field at the core surface, through the radial component of the magnetic induction equation. That part of the model connects the dynamics and the observed secular variation, with the radial component of the magnetic field acting as a passive tracer. We resort to variational data assimilation to formally construct the relationship between model predictions and observations. Variational data assimilation seeks to minimize an objective function by computing its sensitivity to its control variables. The sensitivity is efficiently calculated after integration of the adjoint model. We illustrate that framework with twin experiments, performed first in the case of the kinematic core flow inverse problem and then in the case of Alfvén torsional oscillations. In both cases, using the adjoint model allows us to retrieve core state variables which, while taking part in the dynamics, are not directly sampled at the core surface. We study the effect of several factors on the solution (width of the assimilation time window, amount and quality of data), and we discuss the potential of the model to deal with real geomagnetic observations.

  2. Fast geomagnetic field intensity variations between 1400 and 400 BCE: New archaeointensity data from Germany

    Science.gov (United States)

    Hervé, Gwenaël; Faβbinder, Jörg; Gilder, Stuart A.; Metzner-Nebelsick, Carola; Gallet, Yves; Genevey, Agnès; Schnepp, Elisabeth; Geisweid, Leonhard; Pütz, Anja; Reuβ, Simone; Wittenborn, Fabian; Flontas, Antonia; Linke, Rainer; Riedel, Gerd; Walter, Florian; Westhausen, Imke

    2017-09-01

    Thirty-five mean archaeointensity data were obtained on ceramic sherds dated between 1400 and 400 BCE from sites located near Munich, Germany. The 453 sherds were collected from 52 graves, pits and wells dated by archaeological correlation, radiocarbon and/or dendrochronology. Rock magnetic analyses indicate that the remanent magnetization was mainly carried by magnetite. Data from Thellier-Thellier experiments were corrected for anisotropy and cooling rate effects. Triaxe and multispecimen (MSP-DSC) protocols were also measured on a subset of specimens. Around 60% of the samples provide reliable results when using stringent criteria selection. The 35 average archaeointensity values based on 154 pots are consistent with previous data and triple the Western Europe database between 1400 and 400 BCE. A secular variation curve for central-western Europe, built using a Bayesian approach, shows a double oscillation in geomagnetic field strength with intensity maxima of ∼70 μT around 1000-900 BCE and another up to ∼90 μT around 600-500 BCE. The maximum rate of variation was ∼0.25 μT/yr circa 700 BCE. The secular variation trend in Western Europe is similar to that observed in the Middle East and the Caucasus except that we find no evidence for hyper-rapid field variations (i.e. geomagnetic spikes). Virtual Axial Dipole Moments from Western Europe, the Middle East and central Asia differ by more than 2·1022 A·m2 prior to 600 BCE, which signifies a departure from an axial dipole field especially between 1000 and 600 BCE. Our observations suggest that the regional Levantine Iron Age anomaly has been accompanied by an increase of the axial dipole moment together with a tilt of the dipole.

  3. Long-term variation in the upper atmosphere as seen in the amplitude of the geomagnetic solar quiet daily variation

    Science.gov (United States)

    Shinbori, A.; Koyama, Y.; Hayashi, H.; Nose, M.; Hori, T.; Otsuka, Y.; Tsuda, T.

    2011-12-01

    It has been well-known that geomagnetic solar quiet (Sq) daily variation is produced by global ionospheric currents flowing in the E-region from middle latitudes to the magnetic equator. These currents are generated by a dynamo process via interaction between the neutral wind and ionospheric plasma in a region of the thermosphere and ionosphere. From the Ohm's equation, the ionospheric currents strongly depend on the ionospheric conductivity, polarization electric field and neutral wind. Then, to investigate the Sq amplitude is essential for understanding the long-term variations in the ionospheric conductivity and neutral wind of the thermosphere and ionosphere. Elias et al. [2010] found that the Sq amplitude tends to increase by 5.4-9.9 % in the middle latitudes from 1961 to 2001. They mentioned that the long-term variation of ionospheric conductivity associated with geomagnetic secular variation mainly determines the Sq trend, but that the rest component is ionospheric conductivity enhancement associated with cooling effects in the thermosphere due to increasing the greenhouse gases. In this talk, we clarify the characteristics of the long-term variation in the Sq amplitude using the long-term observation data of geomagnetic field and neutral wind. These observation data have been provided by the IUGONET (Inter-university Upper atmosphere Global Observation NETwork) project. In the present analysis, we used the F10.7 flux as an indicator of the variation in the solar irradiance in the EUV and UV range, geomagnetic field data with time resolution of 1 hour. The definition of the Sq amplitude is the difference of the H-component between the maximum and minimum per day when the Kp index is less than 4. As a result, the Sq amplitude at all the stations strongly depends on 11-year solar activity, and tends to enhance more during the high activities (19- and 22- solar cycles) than during the low activity (20-solar cycle). The Fourier spectra of the F10.7 flux and Sq

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

    Science.gov (United States)

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

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

  5. Bayesian inference of local geomagnetic secular variation curves: application to archaeomagnetism

    Science.gov (United States)

    Lanos, Philippe

    2014-05-01

    The errors that occur at different stages of the archaeomagnetic calibration process are combined using a Bayesian hierarchical modelling. The archaeomagnetic data obtained from archaeological structures such as hearths, kilns or sets of bricks and tiles, exhibit considerable experimental errors and are generally more or less well dated by archaeological context, history or chronometric methods (14C, TL, dendrochronology, etc.). They can also be associated with stratigraphic observations which provide prior relative chronological information. The modelling we propose allows all these observations and errors to be linked together thanks to appropriate prior probability densities. The model also includes penalized cubic splines for estimating the univariate, spherical or three-dimensional curves for the secular variation of the geomagnetic field (inclination, declination, intensity) over time at a local place. The mean smooth curve we obtain, with its posterior Bayesian envelop provides an adaptation to the effects of variability in the density of reference points over time. Moreover, the hierarchical modelling also allows an efficient way to penalize outliers automatically. With this new posterior estimate of the curve, the Bayesian statistical framework then allows to estimate the calendar dates of undated archaeological features (such as kilns) based on one, two or three geomagnetic parameters (inclination, declination and/or intensity). Date estimates are presented in the same way as those that arise from radiocarbon dating. In order to illustrate the model and the inference method used, we will present results based on French, Bulgarian and Austrian datasets recently published.

  6. Correlation Between Time Change in Modulus of Short-Period Geomagnetic Variation and Seismicity in Taiwan

    Directory of Open Access Journals (Sweden)

    Kuang-Jung Chen

    2007-01-01

    Full Text Available In this study, geomagnetic data of the Lunping observatory from 1993 to 2000 are utilized for computing the amplitude variation of short-period geomagnetic total intensity data, using the complex demodulation method (CD method. In order to compare these time changes with seismicity, earthquakes that occurred within 150 km of Lunping, with magnitude ML greater than 3.0, are located. The total sum of those earthquakes, summed month by month, is correlated with the modulus. After removing seasonal effect, our results show that the modulus of periods 24, 12, and 8 hr reveals a notable change that seems to be related to the total sum of events within the whole study period. One possible precursor is found 6 months prior to the 1999 high seismicity. The modulus for the periods 24, 12, and 8 hr increased gradually from the beginning of 1999 to August 1999. After earthquake occurrence the modulus decreased again to a normal level. We propose that this notable increase might be related to a preparation process for this strong earthquake.

  7. Geomagnetic field variations in Western Europe from 1500BC to 200AD. Part I: Directional secular variation curve

    Science.gov (United States)

    Hervé, Gwenaël; Chauvin, Annick; Lanos, Philippe

    2013-05-01

    To improve the geomagnetic field secular variation curve (SVC) of Western Europe during protohistoric times, archaeomagnetic directions of 39 archaeological kilns or hearths from France were investigated. The dating of each archaeological structure was established with archaeological or chronometric methods. Thirty-seven of these structures are dated from the first millennium BC, one from the end of the second millennium BC and the last one from the fourth millennium BC. Thermomagnetic curves, unblocking temperatures and coercivities suggest that the main carrier of the remanent magnetization is a Ti-poor titanomagnetite. Archaeodirections were obtained by alternating field and thermal demagnetizations on almost 900 specimens. The anisotropy tensor of thermoremanent magnetization was determined for 35 structures and 22 mean archaeodirections were corrected for anisotropy. The new archaeodirections are very consistent with previously published data. A new directional SVC was built using bivariate statistics with selected Western Europe data located within 1000 km of Paris. Selection criteria include the number of samples, the dating reliability and the accuracy of the mean archaeodirection. Resulting secular variation between 1500BC and 0AD mainly shows large changes in declination, while inclinations are bracketed between ˜65° and ˜75°. The declinations show a strong maximum with values ˜30-35° around 800-750BC, followed by a sharp decrease to values around 0° at 500BC and close to -7° around 250BC. The main features of the secular variation from 1500BC to 0AD appear to be a dominant westward drift and two major changes around 800 and 250BC. Compared to the global and regional geomagnetic models, the new reference data are better fitted by ARCH3k_cst.1 and SCHA.DIF.3k than by ARCH3k.1 and CALS3k.4 models. The strong variation of the archaeodirection between 1000 and 500BC makes archaeomagnetism very useful for dating purposes.

  8. Geomagnetic field variations in Western Europe from 1500 BC to 200 AD. Part II: New intensity secular variation curve

    Science.gov (United States)

    Hervé, Gwenaël; Chauvin, Annick; Lanos, Philippe

    2013-05-01

    In order to extend the secular variation curve (SVC) of archaeointensity in Western Europe to the first millennium BC, we studied 24 kilns and hearths in place, two displaced hearths and six sets of pottery sherds from French archaeological sites. Archaeological artefacts, radiocarbon and dendrochronology dated the acquisition of the thermoremanent magnetization (TRM) carried by the studied objects. Rock magnetism experiments suggest that the main carrier of the magnetization is a Ti-poor titanomagnetite. Archaeointensity was determined by the Thellier-Thellier classical protocol with pTRM-checks. A strict criteria set was applied to select only the most reliable results with linear NRM-TRM diagrams (55% of total specimens). This study demonstrates that pottery sherds with two TRMs give reliable archaeointensities in the low-temperature interval, if the NRM-TRM diagram is adequately adjusted. Eighteen new mean archaeointensities (14 corrected from the anisotropy of TRM and 16 from cooling rate) were computed. The comparison with previously published Western Europe paleointensities show a strong dispersion between data primarily due to their variable quality. Western Europe data were weighted following the archaeointensity protocol, the number of specimens per site and the type of studied materials, in order to better highlight the secular variation of archaeointensity during the first millennium BC. The SVC, built with sliding windows of 160 years shifted every 50 years, presents (at Paris) a maximum of 90 μT around 800 BC and a minimum of 60 μT around 250 BC. These archaeointensity maximum and minimum correspond to cusps of the geomagnetic field direction in Western Europe. This new curve is consistent with Mesopotamian and Eastern Europe data. The archaeointensity secular variation in Western Europe predicted by global geomagnetic models CALS3k.4, ARCH3k.1 and ARCH3k_cst.1 is smoother than our SVC. We used our directional dataset (Hervé et al., 2013) to build

  9. Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

    Science.gov (United States)

    Connor, Hyunju Kim; Zesta, Eftyhia; Fedrizzi, Mariangel; Shi, Yong; Raeder, Joachim; Codrescu, Mihail V.; Fuller-Rowell, Tim J.

    2016-06-01

    The magnetosphere is a major source of energy for the Earth's ionosphere and thermosphere (IT) system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the storm-time dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM) coupled with the Coupled Thermosphere Ionosphere Model (CTIM). OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD) equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe). CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at ~ 400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset, which in turn

  10. Constraints on geomagnetic secular variation modeling from electromagnetism and fluid dynamics of the Earth's core

    Science.gov (United States)

    Benton, E. R.

    1986-01-01

    A spherical harmonic representation of the geomagnetic field and its secular variation for epoch 1980, designated GSFC(9/84), is derived and evaluated. At three epochs (1977.5, 1980.0, 1982.5) this model incorporates conservation of magnetic flux through five selected patches of area on the core/mantle boundary bounded by the zero contours of vertical magnetic field. These fifteen nonlinear constraints are included like data in an iterative least squares parameter estimation procedure that starts with the recently derived unconstrained field model GSFC (12/83). Convergence is approached within three iterations. The constrained model is evaluated by comparing its predictive capability outside the time span of its data, in terms of residuals at magnetic observatories, with that for the unconstrained model.

  11. A model of the geomagnetic field and its secular variation for epoch 2000 estimated from Orsted data

    DEFF Research Database (Denmark)

    Olsen, Nils

    2002-01-01

    as measured simultaneously by globally distributed geomagnetic observatories. In addition, the observatory data are used to constrain secular variation. The model is estimated using an iteratively reweighted least-squares method with Huber weights to account for the non-Gaussian data error distribution...

  12. Paleosecular variation record of geomagnetic full vector during late Miocene, from the Nayarit area, Mexico

    Science.gov (United States)

    Goguitchaichvili, Avto; Alva Valdivia, Luis M.; Elguera, Jose Rosas; Fucugauchi, Jaime Urrutia; Cervantes, Miguel Angel; Morales, Juan

    2002-11-01

    We have sampled a sequence of 45 late Miocene consecutive lava flows in the Tepic area (Nayarit State, Mexico). The age of the volcanic units lies between 8 and 9 million years (Ma) according to available radiometric data. All samples were stepwise demagnetized, partly with alternating field (AF), partly thermally with very similar results. Most of the rocks exhibited well-defined one component remanent magnetisation with high unblocking temperatures (mostly above 525 °C) and high median destructive fields (MDF) (40-50 mT). Rock-magnetic experiments combined with microscopy show that, in most cases, the main magnetic mineral is Ti-poor titanomagnetite associated with exsoluted ilmenite. Continuous susceptibility measurements with temperature and hysteresis experiments yield in most cases nearly reversible curves with Curie points close to that of magnetite and pseudo-single-domain characteristics. Characteristic remanent magnetisations (ChRM) isolated after the first steps of demagnetisation are all normal polarity. According to the dispersion of virtual geomagnetic pole (VGP) directions, paleosecular variation was abnormally lower than the one observed in general during Miocene. Considering our paleomagnetic results together with available radiometric data, it seems that the volcanic units have been emplaced during a very short time span of about 0.08 million years. The mean paleomagnetic directions obtained from this study do not differ significantly from that expected for the middle Miocene. Thirty-one samples from eight individual flows yielded acceptable paleointensity estimates. The site mean paleointensities range from 27.8±0.9 to 42.0±7.9 μT. The virtual dipole moments (VDM) range from 5.9 to 9.5×10 22 Am 2. This corresponds to a mean value of 7.6±1.4×10 22 Am 2, which is higher than the average VDM value for late Miocene. Altogether our data suggest the existence of relatively high geomagnetic field strength undergoing low fluctuations. These

  13. Climatology of rapid geomagnetic variations at high latitudes over two solar cycles

    Directory of Open Access Journals (Sweden)

    A. Viljanen

    2011-10-01

    Full Text Available We investigate the characteristics of rapid geomagnetic variations at high latitudes based on the occurrence of large time derivatives of the horizontal magnetic field (dH/dt exceeding 1 nT s−1. Analysis of IMAGE magnetometer data from North Europe in 1983–2010, covering more than two solar cycles, confirms and specifies several previous findings. We show that dH/dt activity is high around the midnight and early morning hours, and nearly vanishes at noon and early afternoon. This happens during all seasons, although the midnight maximum is nearly invisible during summer. As indicated by modelled ionospheric equivalent currents, large dH/dt values occur predominantly during westward ionospheric electrojets. Before and around midnight, dH/dt tends to be north-south oriented, whereas in the morning hours, its direction is more west-east directed. dH/dt tends to be more strictly north-south oriented during winter than other seasons. The seasonal occurrence of large dH/dt values is similar to the variation of the maximum amplitude of westward equivalent currents. The yearly fraction of east-west directed large dH/dt vectors at the Kilpisjärvi station (MLAT 65.88 varies from 31 to 47 % without any clear correlation with the general geomagnetic activity nor with the yearly averages of solar wind parameters.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chu, W. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather; Univ. of Chinese Academy of Sciences, Beijing (China). College of Earth Sciences; Qin, G. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather

    2016-04-01

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

  15. Similarity and differences in morphology and mechanisms of the foF2 and TEC disturbances during the geomagnetic storms on 26–30 September 2011

    Directory of Open Access Journals (Sweden)

    M. V. Klimenko

    2017-08-01

    Full Text Available This study presents an analysis of the ground-based observations and model simulations of ionospheric electron density disturbances at three longitudinal sectors (eastern European, Siberian and American during geomagnetic storms that occurred on 26–30 September 2011. We use the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP to reveal the main mechanisms influencing the storm-time behavior of the total electron content (TEC and the ionospheric F2 peak critical frequency (foF2 during different phases of geomagnetic storms. During the storm's main phase the long-lasting positive disturbances in TEC and foF2 at sunlit mid-latitudes are mainly explained by the storm-time equatorward neutral wind. The effects of eastward electric field can only explain the positive ionospheric storm in the first few hours of the initial storm phase. During the main phase the ionosphere was more changeable than the plasmasphere. The positive disturbances in the electron content at the plasmaspheric heights (800–20 000 km at high latitudes can appear simultaneously with the negative disturbances in TEC and foF2. The daytime positive disturbances in foF2 and TEC occurred at middle and low latitudes and at the Equator due to n(O ∕ n(N2 enhancement during later stage of the main phase and during the recovery phase of the geomagnetic storm. The plasma tube diffusional depletion and negative disturbances in electron and neutral temperature were the main formation mechanisms of the simultaneous formation of the positive disturbances in foF2 and negative disturbances in TEC at low latitudes during the storm's recovery phase.

  16. Bulgarian Geomagnetic Reference Field (BulGRF) for 2015.0 and secular variation prediction model up to 2020

    Science.gov (United States)

    Metodiev, Metodi; Trifonova, Petya

    2017-09-01

    The Bulgarian Geomagnetic Reference Field (BulGRF) for 2015.0 epoch and its secular variation model prediction up to 2020.0 is produced and presented in this paper. The main field model is based on the well-known polynomial approximation in latitude and longitude of the geomagnetic field elements. The challenge in our modelling strategy was to update the absolute field geomagnetic data from 1980.0 up to 2015.0 using secular measurements unevenly distributed in time and space. As a result, our model gives a set of six coefficients for the horizontal H, vertical Z, total field F, and declination D elements of the geomagnetic field. The extrapolation of BulGRF to 2020 is based on an autoregressive forecasting of the Panagyurishte observatory annual means. Comparison of the field values predicted by the model with Panagyurishte (PAG) observatory annual mean data and two vector field measurements performed in 2015 shows a close match with IGRF-12 values and some difference with the real (measured) values, which is probably due to the influence of crustal sources. BulGRF proves to be a reliable alternative to the global geomagnetic field models which together with its simplicity makes it a useful tool for reducing magnetic surveys to a common epoch carried out over the Bulgarian territory up to 2020.

  17. Response of nighttime equatorial and low latitude F-region to the geomagnetic storm of August 18, 2003, in the Brazilian sector

    Science.gov (United States)

    Sahai, Y.; Becker-Guedes, F.; Fagundes, P. R.; Lima, W. L. C.; Otsuka, Y.; Huang, C.-S.; Espinoza, E. S.; Pi, X.; de Abreu, A. J.; Bolzan, M. J. A.; Pillat, V. G.; Abalde, J. R.; Pimenta, A. A.; Bittencourt, J. A.

    This paper presents an investigation of geomagnetic storm effects in the equatorial and low latitude F-region in the Brazilian sector during the intense geomagnetic storm on 18 August, 2003 (SSC 14:21 UT on 17/08; ΣKp = 52+; Ap = 108; ∣Dst∣ max = 168 at 1600 UT on 18/08). Simultaneous ionospheric sounding measurements from two stations, viz., Palmas (10.2°S, 48.2°W; dip latitude 5.7°S) and Sao Jose dos Campos (23.2°S, 45.9°W; dip latitude 17.6°S), Brazil, are presented for the nights of 16-17, 17-18 and 18-19 August, 2003 (quiet, disturbed and recovery phases). Both stations are equipped with the Canadian Advanced Digital Ionosonde (CADI). Quiet and disturbed conditions of the F-region ionosphere are compared using data collected from the two stations. The relationship between magnetospheric disturbance and low-latitude ionospheric dynamics, and generation of ionospheric irregularities are discussed. On the disturbed nights (17-18 and 18-19 August), the low latitude station S. J. Campos showed strong enhancements in the F-region critical frequency (foF2), whereas the near equatorial station Palmas showed strong uplifting of the F-layer about 1 h earlier. Normally during the June solstice months (May-August) in the Brazilian sector, large-scale ionospheric irregularities in form of plasma bubbles are rarely observed. On the night of 17-18 August, ionsospheric sounding observations at Palmas showed the presence of bottomside spread-F, whereas on the night of 18-19 August, the observations at Palmas and S. J. Campos showed the presence of plasma bubbles when the storm recovery phase had just started. The complementary GPS data available from several stations in the "Rede Brasileira de Monitoramento Continuo de GPS (Brazilian Network for Continuous GPS Monitoring)" are used to obtain the vertical total electron content (VTEC) and the rate of change of TEC per minute on UT days 18 and 19 August, 2003 and presented. Also, several global ionospheric TEC maps

  18. A case for variational geomagnetic data assimilation: insights from a one-dimensional, nonlinear, and sparsely observed MHD system

    Directory of Open Access Journals (Sweden)

    A. Fournier

    2007-01-01

    Full Text Available Secular variations of the geomagnetic field have been measured with a continuously improving accuracy during the last few hundred years, culminating nowadays with satellite data. It is however well known that the dynamics of the magnetic field is linked to that of the velocity field in the core and any attempt to model secular variations will involve a coupled dynamical system for magnetic field and core velocity. Unfortunately, there is no direct observation of the velocity. Independently of the exact nature of the above-mentioned coupled system – some version being currently under construction – the question is debated in this paper whether good knowledge of the magnetic field can be translated into good knowledge of core dynamics. Furthermore, what will be the impact of the most recent and precise geomagnetic data on our knowledge of the geomagnetic field of the past and future? These questions are cast into the language of variational data assimilation, while the dynamical system considered in this paper consists in a set of two oversimplified one-dimensional equations for magnetic and velocity fields. This toy model retains important features inherited from the induction and Navier-Stokes equations: non-linear magnetic and momentum terms are present and its linear response to small disturbances contains Alfvén waves. It is concluded that variational data assimilation is indeed appropriate in principle, even though the velocity field remains hidden at all times; it allows us to recover the entire evolution of both fields from partial and irregularly distributed information on the magnetic field. This work constitutes a first step on the way toward the reassimilation of historical geomagnetic data and geomagnetic forecast.

  19. Low-latitude ionosphere response to super geomagnetic storm of 17/18 March 2015: Results from a chain of ground-based observations over Indian sector

    Science.gov (United States)

    Ramsingh; Sripathi, S.; Sreekumar, Sreeba; Banola, S.; Emperumal, K.; Tiwari, P.; Kumar, Burudu Suneel

    2015-12-01

    In this paper, we present unique results of equatorial and low-latitude ionosphere response to one of the major geomagnetic storms of the current solar cycle that occurred during 17-18 March 2015, where Dst reached its minimum of -228 nT. Here we utilized data from magnetometers, chain of ionosondes located at Tirunelveli (8.73°N, 77.70°E; geometry: 0.32°N), Hyderabad (17.36°N, 78.47°E; geometry 8.76°N), and Allahabad (25.45°N, 81.85°E; geometry 16.5°N) along with multistation GPS receivers over Indian sector. The observations showed a remarkable increase of h'F to as high as ~560 km over Tirunelveli (magnetic equator) with vertical drift of ~70 m/s at 13:30 UT due to direct penetration of storm time eastward electric fields which exactly coincided with the local time of pre-reversal enhancement (PRE) and caused intense equatorial spread F irregularities in ionosondes and scintillations in GPS receivers at wide latitudes. Plasma irregularities are so intense that their signatures are seen in Allahabad/Lucknow. Storm time thermospheric meridional winds as estimated using two ionosondes suggest the equatorward surge of gravity waves with period of ~2 h. Suppression of anomaly crest on the subsequent day of the storm suggests the complex role of disturbance dynamo electric fields and disturbance wind effects. Our results also show an interesting feature of traveling ionospheric disturbances possibly associated with disturbance meridional wind surge during recovery phase. In addition, noteworthy observations are nighttime westward zonal drifts and PRE-related total electron content enhancements at anomaly crests during main phase and counter electrojet signatures during recovery phase.

  20. Mid-Latitude Pc1, 2 Pulsations Induced by Magnetospheric Compression in the Maximum and Early Recovery Phase of Geomagnetic Storms

    Institute of Scientific and Technical Information of China (English)

    N. A. Zolotukhina; I.P. Kharchenko

    2005-01-01

    We investigate the properties of interplanetary inhomogeneities generating long-lasting mid-latitude Pc1, 2 geomagnetic pulsations. The data from the Wind and IMP 8 spacecrafts, and from the Mondy and Borok midlatitude magnetic observatories are used in this study. The pulsations under investigation develop in the maximum and early recovery phase of magnetic storms. The pulsations have amplitudes from a few tens to several hundred pT andlast more than seven hours. A close association of the increase (decrease) in solar wind dynamic pressure (Psw) with the onset or enhancement (attenuation or decay) of these pulsations has been established. Contrary to high-latitude phenomena, there is a distinctive feature of the interplanetary inhomogeneities that are responsible for generation of long-lasting mid-latitude Pc1, 2. It is essential that the effect of the quasi-stationary negative Bz-component of the interplanetary magnetic field on the magnetosphere extends over 4 hours. Only then are the Psw pulses able to excite the above-mentioned type of mid-latitude geomagnetic pulsations. Model calculations show that in the cases under study the plasmapause can form in the vicinity of the magnetic observatory. This implies that the existence of an intense ring current resulting from the enhanced magnetospheric convection is necessary for the Pc1, 2 excitation. Further, the existence of the plasmapause above the observation point (as a waveguide) is necessary for long-lasting Pc1 waves to arrive at the ground.

  1. Multifluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms-Initial Results

    Science.gov (United States)

    Glocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J.-C.; Kistler, L. M.

    2009-01-01

    The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered

  2. Multi-Fluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms, Initial Results

    Science.gov (United States)

    Gkocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J. C.; Kistler, L. M.

    2010-01-01

    The magnetosphere contains a significant amount of ionospheric O{+}, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the BATS-R-US model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multi-fluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single- fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multi-fluid MHD model (with outflow) gives comparable results to the multi-species MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multi-species and multi-fluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H{+} and O(+}, which is not possible when utilizing the other techniques considered.

  3. Multifluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms-Initial Results

    Science.gov (United States)

    Glocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J.-C.; Kistler, L. M.

    2009-01-01

    The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered

  4. Specific interplanetary conditions for CIR-, Sheath-, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis

    Directory of Open Access Journals (Sweden)

    Yu. I. Yermolaev

    2010-12-01

    Full Text Available A comparison of specific interplanetary conditions for 798 magnetic storms with Dst <−50 nT during 1976–2000 was made on the basis of the OMNI archive data. We categorized various large-scale types of solar wind as interplanetary drivers of storms: corotating interaction region (CIR, Sheath, interplanetary CME (ICME including both magnetic cloud (MC and Ejecta, separately MC and Ejecta, and "Indeterminate" type. The data processing was carried out by the method of double superposed epoch analysis which uses two reference times (onset of storm and minimum of Dst index and makes a re-scaling of the main phase of the storm in a such way that all storms have equal durations of the main phase in the new time reference frame. This method reproduced some well-known results and allowed us to obtain some new results. Specifically, obtained results demonstrate that (1 in accordance with "output/input" criteria the highest efficiency in generation of magnetic storms is observed for Sheath and the lowest one for MC, and (2 there are significant differences in the properties of MC and Ejecta and in their efficiencies.

  5. Parallel Computation of Spatio-Temporal Variations of Geomagnetic Field Using One-Minute Time Resolution Dataset

    Directory of Open Access Journals (Sweden)

    Felix Ale

    2012-11-01

    Full Text Available This work presents a novel method for analyzing spatio-temporal variations of geomagnetic field using parallel computing. One-minute resolution geomagnetic dataset of 1996 was obtained from INTERMAGNET global network of 64 observatory stations. In effect, large and three dimensional arrays of geomagnetic observations are to be processed. Thus, sequential and parallel algorithms were developed using MATLAB 2012a, interfaced with the well-known kriging method for efficient geostatistical data gridding and mapping of solar quiet (Sq daily variations. The runtime of the sequential algorithm on a processor took 18.5 minutes while the corresponding parallel algorithm took 2.95 minutes using eight Intel Xeon E5410 2.33GHz processors in parallel. The efficiency profile of the model is logarithmic in nature. This was further optimized using quadratic polynomial interpolation. The results show that 13 processors will process the Sq in less than one minute, thus providing effective near real-time observation of Space weather. In addition, the foci of the generated finer Sq(H plots revealed temporal variability that is consistently maximized at local noon at every location on this geomagnetic environment as demonstrated in the 2D visual display.

  6. Physical meaning of the equinoctial effect for semi-annual variation in geomagnetic activity

    Directory of Open Access Journals (Sweden)

    A. Yoshida

    2009-05-01

    Full Text Available Physical meaning of the equinoctial effect for semi-annual variation in geomagnetic activity is investigated based on the three-hourly am index and solar wind parameters. When the z component of the interplanetary magnetic field (IMF in geocentric solar magnetospheric (GSM coordinates is southward, am indices are well correlated with BsVx2, where Bs is the southward component of the IMF and Vx is the solar wind velocity in the sun-earth direction. The am-BsVx2 relationship, however, depends on the range of Vx2: the am in higher ranges of Vx2 tends to be larger than am in lower ranges of Vx2 for the same value of BsVx2 for both equinoctial and solstitial epochs. Using the data sets of the same Vx2 range, it is shown that distribution of points in the am-BsVx2 diagram at the solstitial epochs overlaps with that at the equinoctial epochs and the average am values in each BsVx2 bin in solstitial epochs are closely consistent with those in equinoctial epochs, if Vx2 for each point at solstices are reduced to Vx2sin2 (Ψ where Ψ is the geomagnetic colatitude of the sub-solar point. Further, it is shown that monthly averages of the am index in the long period is well correlated with the values of sin2(ψ for the middle day of each month. These findings indicate that the factor that contributes to the generation of geomagnetic disturbance is not the velocity of the solar wind, but the component of the solar wind velocity perpendicular to the dipole axis of the geomagnetic

  7. Effects of geomagnetic disturbances in daytime variations of the atmospheric electric field in polar regions

    Science.gov (United States)

    Kleimenova, N. G.; Kubicki, M.; Odzimek, A.; Malysheva, L. M.; Gromova, L. I.

    2017-05-01

    We have studied the influence of daytime polar substorms (geomagnetic bays under the IMF Bz > 0) on variations of the vertical gradient of the atmospheric electric field potential ( Ez) observed at the Polish Hornsund Station (Svalbard, Norway). Only the observations of Ez under "fair weather" conditions were used, i.e. in the absence of strong wind, precipitations, low cloud cover, etc. We studied more than 20 events of daytime polar substorms registered by the Scandinavian chain of IMAGE magnetometers in 2010-2014 during the "fair weather" periods at the Hornsund Station. Analysis of the observations showed that Ez significantly deviates from the its background variations during daytime, as a rule, when the Hornsund Station is in the region of projection of the daytime auroral oval, the position of which was determined from OVATION data. It was shown that the development of a daytime polar substorm leads to fluctuating enhance of Ez values. It was found that Ez surges are accompanied by intensification of field-aligned electric currents outflowing from the ionosphere, which were calculated from the data of low-orbit communication satellites of the AMPERE project.

  8. Spatial and Temporal Variations in the Geomagnetic Field Determined From the Paleomagnetism of Sediment Cores From Scientific Ocean Drilling

    Science.gov (United States)

    Acton, G.

    2014-12-01

    Quantifying the spatial and temporal variations of the main geomagnetic field at Earth's surface is important for understanding underlying geodynamo processes and conditions near the core-mantle boundary. Much of the geomagnetic variability, known as secular variation, occurs on timescales of tens of years to many thousands of years, requiring the use of paleomagnetic observations to derive continuous records of the ancient field, referred to as paleosecular variation (PSV) records. Marine depositional systems where thick sedimentary sections accumulate at high sedimentation rates provide some of the best locations for obtaining long continuous PSV records that can reveal both the short- and long-term changes in the field. Scientific ocean drilling has been successful at recovering many such sections and the paleomagnetic records from these reveal how the amplitude of PSV differs between sites and through time. In this study, several such records cored during Ocean Drilling Program (ODP), Integrated Ocean Drilling Program (IODP), and other cruises from high, mid, and low latitudes will be used to quantify time intervals of low and high PSV, to examine time-average properties of the field, to map spatial variations in the angular dispersion of the virtual geomagnetic pole (VGP), and to assess whether the spatial variation in angular dispersion changes with time.

  9. AN UPDATE OF ITALIAN ARCHEAOINTENSITY DATA AND GEOMAGNETIC FIELD STRENGTH VARIATION DURING THE LAST THREE MILLENNIA

    Science.gov (United States)

    Tema, E.; Goguitchaichrili, A.

    2009-12-01

    Beside of the impressive cultural heritage and the abundant archaeological sites, Italian archaeointensity data are still sparse. We present here a new compilation and analysis of existing absolute intensity data in order to estimate the variation of the Earth’s magnetic field over the past three millennia. The current dataset consists of 140 intensity data mainly belonging to southern Italy. Vesuvius and Etna contribute 83 per cent of total while only 17 per cent comes from archaeological material. The time distribution is also irregular with the majority of determinations concentrated at the last four centuries. Still, older periods are very poorly covered. All data have been reduced at the latitude of Viterbo (42.45° N, 12.03° E) and plotted versus time. Data coming from historical volcanic eruptions show important discrepancies while those coming from archaeological material are still not sufficiently numerous to reliably describe the fine characteristics of geomagnetic field intensity variations. In order to increase the representativity of the data, archaeointensity results from nearby regions (approximately 700 km and 900 km radius from Viterbo) have been considered. The 700 km circle dataset still remains poor with only 20 additional data added. In contrast, the 900 km dataset includes 122 more archaeointensity data mainly coming from France, Switzerland, Czech Republic, Slovakia, Hungary, Greece and Bulgaria that partially fill the gap between 4-7th centuries BC and 3-4th and 9-11th AD for which no Italian data are available. A preliminary Italian intensity secular variation curve has been calculated by using sliding windows of 100 years shifted by 50 years. The results have been compared with regional and global models predictions. Clearly more Italian archaeointensity data are still needed in order to draw a robust Italian intensity secular variation curve that could be used for archaeomagnetic dating in combination with directional data.

  10. Monitoring of the mass density profile along the 0° geomagnetic longitude during magnetic storms with the use of ground magnetometers.

    Science.gov (United States)

    Romanova, N.; Stepanova, M. V.; Kozyreva, O. V.; Pilipenko, V.; Zesta, E.

    2015-12-01

    Ground magnetometers offer a very cheap and robust means of globally monitoring the magnetospheric mass density, by determining the ULF field line resonant frequency. ULF waves are almost always present in near-Earth environment and are generated by the solar wind interaction with the terrestrial magnetosphere. These waves from the magnetopause propagate through the magnetosphere. When they encounter a field line that resonates at the same frequency, coupling to the Alfven field line oscillations occurs and the resonance can be detected on the ground at that particular latitude. There are different methods for determining resonant frequencies from ground ULF waves. the density profiles along the 0° geomagnetic longitude were obtained using both the gradient and the amplitude-phase methods for the analysis of the magnetic field data from the magnetometer arrays: SAMBA (South American Meridional B-field Array), MAGDAS and American Antarctic bases (Palmer, WAIS-D). We compared the density profiles during quiet magnetic conditions and during strong magnetic storms (recovery phase). It is shown that in the recovery phase of strong magnetic storms (Dst <-150 nT) profile of the equatorial mass density varies greatly in comparison with the density distribution in quiet days.

  11. Geomagnetically Induced Currents: Principles

    Science.gov (United States)

    Oliveira, Denny M.; Ngwira, Chigomezyo M.

    2017-10-01

    The geospace, or the space environment near Earth, is constantly subjected to changes in the solar wind flow generated at the Sun. The study of this environment variability is called Space Weather. Examples of effects resulting from this variability are the occurrence of powerful solar disturbances, such as coronal mass ejections (CMEs). The impact of CMEs on the Earth's magnetosphere very often greatly perturbs the geomagnetic field causing the occurrence of geomagnetic storms. Such extremely variable geomagnetic fields trigger geomagnetic effects measurable not only in the geospace but also in the ionosphere, upper atmosphere, and on and in the ground. For example, during extreme cases, rapidly changing geomagnetic fields generate intense geomagnetically induced currents (GICs). Intense GICs can cause dramatic effects on man-made technological systems, such as damage to high-voltage power transmission transformers leading to interruption of power supply, and/or corrosion of oil and gas pipelines. These space weather effects can in turn lead to severe economic losses. In this paper, we supply the reader with theoretical concepts related to GICs as well as their general consequences. As an example, we discuss the GIC effects on a North American power grid located in mid-latitude regions during the 13-14 March 1989 extreme geomagnetic storm. That was the most extreme storm that occurred in the space era age.

  12. The Challenge of Predicting the Occurrence of Intense Storms

    Indian Academy of Sciences (India)

    Nandita Srivastava

    2006-06-01

    Geomagnetic super-storms of October and November 2003 are compared in order to identify solar and interplanetary variables that influence the magnitude of geomagnetic storms. Although these super-storms (DST < -300 nT) are associated with high speed CMEs, their DST indices show large variation. The most intense storm of November 20, 2003 (DST ∼ -472 nT) had its source in a comparatively small active region and was associated with a relatively weaker, M-class flare, while the others had their origins in large active regions and were associated with strong X-class flares. An attempt has been made to implement a logistic regression model for the prediction of the occurrence of intense/super-intense geomagnetic storms. The model parameters (regression coefficients) were estimated from a training data-set extracted from a data-set of 64 geo-effective CMEs observed during 1996–2002. The results indicate that logistic regression models can be effectively used for predicting the occurrence of major geomagnetic storms from a set of solar and interplanetary factors. The model validation shows that 100% of the intense storms (-200 nT < DST < -100 nT) and only 50% of the super-intense (DST < -200 nT) storms could be correctly predicted.

  13. Variation of strong dust storm events in Northern China during 1978-2007

    Science.gov (United States)

    Wang, Ruxing; Liu, Bo; Li, Huiru; Zou, Xueyong; Wang, Jingpu; Liu, Wei; Cheng, Hong; Kang, Liqiang; Zhang, Chunlai

    2017-01-01

    Dust storms have a great significance for global mineral aerosol cycle, marine ecosystem, air quality and human health. Dust storm frequency (DSF), often used as a primary index for understanding a regional characteristic of dust storms. However, DSF couldn't describe the frequency and the outbreak areas of a dust storm event (DSE) which was defined as a dust storm occurred at three or more meteorological stations during the same weather process, because a DSE might occur at several meteorological stations and continue for several days. We defined a new index DSE considering the factors including wind speed, wind direction and spatial variation during a dust storm process. To clarify which index of DSF or DSE is better to describe the characteristics of dust storms, we have used the data sets of dust storm from 319 meteorological stations to calculate the frequency of DSE, and the outbreak area and the duration of each DSE in 1978-2007, as well as to compare the differences between DSE and DSF in spatiotemporal distribution in Northern China. The results showed that the high-value locations of occurrence numbers of DSE and DSF were almost overlapped; from 1978 to 2007, the total values of DSE and DSF decreased from 558 to 201 and from 1273 to 467, respectively, but the mean values of outbreak area and duration of DSE have wavily increased since 1991. These implied that the differences existed between DSE and DSF in describing the characteristics of a regional dust storm, and DSE was a better index for a dust storm to identify the fact of occurrence frequency and outbreak area. The implication of this study was that the values of DSE and DSF have a decrease trends with increase of extreme precipitation events and decrease of mean wind speed under the global warming scenarios, but strong dust storms, which is defined as the outbreak area of an event > 105 km2 here, probably bring greater risk in future.

  14. Response of equatorial and low latitude ionosphere to 2015 St. Patrick's Day super geomagnetic storm: Results from a chain of ground based observations over Indian region

    Science.gov (United States)

    Samireddipalle, Sripathi; Singh, Ram; Sreekumar, Sreeba; Suneel Kumar, Buduru

    2016-07-01

    In this paper, we present unique results of equatorial and low latitude ionosphere response to one of the major geomagnetic storms of the current solar cycle that occurred during 17-18 March 2015 where Dst reached its minimum of -228 nT. Here we utilized data from magnetometers, chain of ionosondes located at Tirunelveli (8.73°N, 77.70°E; geom: 0.320N), Hyderabad (17.360N, 78.470E; geom: 8.760N) and Allahabad (25.45°N, 81.85°E; geom: 16.50N) along with multi station GPS receivers over Indian sector. The observations showed a remarkable increase of h'F to as high as ~560 km over Tirunelveli (magnetic equator) with vertical drift of ~70 m/s at 13:30 UT due to direct penetration of storm time eastward electric fields which exactly coincided with the local time of Pre-Reversal Enhancement (PRE) and caused intense ESF irregularities in ionosondes and scintillations in GPS receivers at wide latitudes. Plasma irregularities are so intense that their signatures are seen in Allahabad/Lucknow. Stormtime thermospheric meridional winds as estimated using two ionosondes suggest the equatorward surge of gravity waves with period of ~2 hrs. Suppression of anomaly crest on the subsequent day of the storm suggests the complex role of disturbance dynamo electric fields and disturbance wind effects. Our results also show an interesting feature of Traveling Ionospheric Disturbances (TIDs) possibly associated with disturbance meridional wind surge during recovery phase. In addition, noteworthy observations are nighttime westward zonal drifts and PRE related TEC enhancements at anomaly crests during main phase and CEJ signatures during recovery phase.

  15. Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

    Directory of Open Access Journals (Sweden)

    Connor Hyunju Kim

    2016-01-01

    Full Text Available The magnetosphere is a major source of energy for the Earth’s ionosphere and thermosphere (IT system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the storm-time dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM coupled with the Coupled Thermosphere Ionosphere Model (CTIM. OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe. CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at ~ 400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset

  16. Archaeomagnetic results from southern Italy and their bearing on geomagnetic secular variation

    Science.gov (United States)

    Evans, M. E.; Hoye, G. S.

    2005-07-01

    Archaeodirectional results from kilns and other baked structures in southern Italy are presented. They are generally compatible with the much larger data sets from France and Bulgaria. In particular, a summary of all the results associated with the well-known eruption of Vesuvius that destroyed Pompeii ( n = 9, D = 355°, I = 58°, α95 = 1.5°) provides a reliable archaeomagnetic anchor point supporting the French and Bulgarian master curves. It is extremely well-constrained in time and it comprises independent studies carried out in four different countries. Furthermore, it is derived from a diverse set of features agreement amongst which argues strongly against significant perturbations due to magnetic refraction, structural disturbance, or depositional shallowing. In terms of geomagnetic secular variation, we interpret the western European archaeomagnetic data summarized here in terms of an open loop caused by westward drift, followed by an inclination low spanning the first few centuries CE representing the signal of a static flux pulse that reaches a maximum magnetic moment of a few percent of the earth's main central dipole.

  17. Retrieving geomagnetic secular variations from lava flows: evidence from Mounts Arso, Etna and Vesuvius (southern Italy)

    Science.gov (United States)

    Incoronato, Alberto; Angelino, Antimo; Romano, Romolo; Ferrante, Agostino; Sauna, Renata; Vanacore, Gianpio; Vecchione, Claudio

    2002-06-01

    Mean directions of magnetization from Mounts Arso (Ischia Island, Gulf of Naples), Etna and Vesuvius lava flows have been determined based on very stringent linearity criteria. These indicate that, regardless of the source volcano, the lava flow mean directions of magnetization form a common path, the SISVC (Southern Italy Secular Variation Curve). This curve enables a reassessment of the age of eruption of several lavas. A date of AD 1169 is demonstrated to be the only possible time of emplacement for one Etna lava flow previously assigned an age of AD 812/1169. It is also demonstrated that two Etna lava flows, which, according to the literature, were emplaced in AD 1536 and 1595 respectively, were actually both emplaced around AD 1037. Three other Etna lava flows, one ascribed to AD 1566 and two to AD 1595, were actually emplaced between AD 1169 and 1284/85. The same time window also holds for a Vesuvius lava flow for which only an upper time threshold was previously available. Only one of the studied flows needs further sampling and analysis to verify whether this flow has been affected by a complete remagnetization or has an erroneous historical dating. The applied procedure seems to be the most appropriate one in carrying out palaeomagnetic surveys of lava flows, as also suggested by the broad agreement with some 17th and 19th century measurements of the geomagnetic field in Rome, relocated to Etna, and is likely to improve knowledge of past history of a volcano significantly.

  18. Decadal to millennial scale geomagnetic field variations in the Levantine archaeointensity curve (LAC): methodology and applications

    Science.gov (United States)

    Shaar, Ron; Tauxe, Lisa; Ron, Hagai; Agnon, Amotz; Ben-Yosef, Erez; Finkelstein, Israel; Zuckerman, Sharon; Levy, Thomas E.

    2014-05-01

    ) according to the dating method employed (archaeological, historical, radiocarbon). In addition, we cross check results from multiple archaeological sites using different source materials dated using different methodologies. The results of this effort are summarized in a regional compilation namely Levantine Archaeomagnetic Curve - LAC. The initial version of the LAC includes recently published data from ancient copper production sites, and new data from two important biblical archaeological mounds in Israel - Tel Megiddo ("Armageddon") and Tel Hazor. In this talk we review our working methodologies, report the current status of the LAC, and discuss its implications on our understanding of geomagnetic secular variations.

  19. The latitudinal variation of geoelectromagnetic disturbances during large (Dst≤-100 nT) geomagnetic storms

    Science.gov (United States)

    Woodroffe, J. R.; Morley, S. K.; Jordanova, V. K.; Henderson, M. G.; Cowee, M. M.; Gjerloev, J. G.

    2016-09-01

    Geoelectromagnetic disturbances (GMDs) are an important consequence of space weather that can directly impact many types of terrestrial infrastructure. In this paper, we analyze 30 years of SuperMAG magnetometer data from the range of magnetic latitudes 20°≤λ≤75° to derive characteristic latitudinal profiles for median GMD amplitudes. Based on this data, we obtain a parameterization of these latitudinal profiles of different types of GMDs, providing an analytical fit with Dst-dependent parameters. We also obtain probabilistic estimates for the magnitudes of "100 year" GMDs, finding that Ḃ = 6.9 (3.60-12.9) nT/s should be expected at 45°≤λ < 50°, exceeding the 5 nT/s threshold for dangerous inductive heating.

  20. Holocene geomagnetic field intensity variations: Contribution from the low latitude Canary Islands site

    Science.gov (United States)

    Kissel, C.; Laj, C.; Rodriguez-Gonzalez, A.; Perez-Torrado, F.; Carracedo, J. C.; Wandres, C.

    2015-11-01

    New absolute paleomagnetic intensity (PI) are investigated from 37 lava flows located at Tenerife and Gran Canaria (Canary Islands). They complete previously published directional results from the same flows and therefore allow to examine the time variations of the full geomagnetic vector. Twenty-eight flows are radiocarbon dated between 1706 AD and about 13 200 BC and one is historical. Eight other flows are not dated but they have stratigraphic links with the dated flows and archeomagnetic ages had been attributed to them based on their paleomagnetic directions. Various mineralogical analyses were conducted, giving access to the nature of the magnetic minerals and to their grain size. We performed the original Thellier and Thellier paleointensity (PI) experiments with a success rate of about 65% coupling this experiment with the strict set of selection criteria PICRIT-03. The mean PIs at the flow level are based on 3 to 12 independent PI determinations except for one site in which only one reliable determination could be obtained. The data indicate some variability in the local field intensity with a prominent PI peak centered around 600 BC and reaching 80 μT (VADM 16 ×1022 Am2), documented for the first time in this region. Combined with the published data obtained from western Africa, Spain, Portugal, Morocco and the Azores within a 2000 km-radius around the Canary Islands, our data allow to construct a curve illustrating the Earth magnetic field intensity fluctuations for Southwestern Europe/Western Africa. This curve, compared to the one produced for the Middle East and one calculated for Central Asia shows that maximum intensity patches have a very large geographical extent. They do not yet appear clearly in the models of variations of the dipolar field intensity.

  1. Geomagnetic intensity variations for the past 8 kyr: New archaeointensity results from Eastern China

    Science.gov (United States)

    Cai, Shuhui; Tauxe, Lisa; Deng, Chenglong; Pan, Yongxin; Jin, Guiyun; Zheng, Jianming; Xie, Fei; Qin, Huafeng; Zhu, Rixiang

    2014-04-01

    In this study, we have carried out paleointensity experiments on 918 specimens spanning the last ∼7 kyr, including pottery fragments, baked clay and slag, collected from Shandong, Liaoning, Zhejiang and Hebei Provinces in China. Approximately half of the specimens yielded results that passed strict data selection criteria and give high-fidelity paleointensities. The virtual axial dipole moments (VADMs) of our sites range from ∼2×1022 to ∼13×1022 Am. At ∼2250 BCE our results suggest a paleointensity low of ∼2×1022 Am, which increases to a high of ∼13×1022 Am by ∼1300 BCE. This rapid (less than 1000 yrs) six-fold change in the paleointensity may have important implications for the dynamics of core flow at this time. Our data from the last ∼3 kyr are generally in good agreement with the ARCH3k.1 model, but deviate significantly at certain time periods from the CALS3k.4 and CALS10k.1b model, which is likely due to differences in the data used to constrain these models. At ages older than ∼3 ka, where only the CALS10k.1b model is available for comparison, our data deviate significantly from the model. Combining our new results with the published data from China and Japan, we provide greatly improved constraints for the regional model of Eastern Asia. When comparing the variations of geomagnetic field in three global representative areas of Eastern Asia, the Middle East and Southern Europe, a common general trend of sinusoidal variations since ∼8 ka is shown, likely dominated by the dipole component. However, significant disparities are revealed as well, which we attribute to non-dipolar components caused by movement of magnetic flux patches at the core-mantle boundary.

  2. Some aspects of the geomagnetic response to solar wind pressure variations: a case study at low and middle latitudes

    Directory of Open Access Journals (Sweden)

    U. Villante

    2004-06-01

    Full Text Available We examined geomagnetic field observations at low and middle latitudes in the Northern Hemisphere during a 50-min interval (12 May 1999, characterized by a complex behaviour of the solar wind dynamic pressure. For the entire interval, the aspects of the geomagnetic response can be organized into four groups of events which show common characteristics for the H and D components, respectively. The correspondence between the magnetospheric field and the ground components reveals different aspects of the geomagnetic response in different magnetic local time (MLT sectors. For the H component, the correspondence is highly significant in the dusk and night sectors; in the dawn and prenoon sectors it shows a dramatic change across a separation line that extends approximately between (6 MLT, 35° and (13 MLT, 60°. For the D component, the correspondence has significant values in the dawn and prenoon regions. We propose a new approach to the experimental data analysis which reveals that, at each station, the magnetospheric field has a close correspondence with the geomagnetic field projection along an axis (M1 that progressively rotates from north/south (night events to east/west orientation (dawn events. When projected along M1, the geomagnetic signals can be interpreted in terms of a one-dimensional pattern that mostly reflects the field behaviour observed at geostationary orbit. Several features appear more evident in this perspective, and the global geomagnetic response to the SW pressure variations appears much clearer than in other representations. In particular, the MLT dependence of the geomagnetic response is much smaller than that one estimated by previous investigations. A clear latitudinal dependence emerges in the dusk sector. The occurrence of low frequency waves at ~2.8mHz can be interpreted in terms of global magnetospheric modes driven by the SW pulse. This event occurred in the recovery phase after the day

  3. 27-day variation of the GCR intensity based on corrected and uncorrected for geomagnetic disturbances data of neutron monitors

    CERN Document Server

    Alania, M V; Wawrzynczak, A; Sdobnov, V E; Kravtsova, M V

    2015-01-01

    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 5 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 ...

  4. Study on noise in simultaneous geomagnetic difference data caused by the effect of Sq local-time variation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new concept is suggested on tectonomagnetic research about the noise in simultaneous geomagnetic difference data caused by the effect of Sq local-time variation, together with the method of theoretical calculation. The level of the noise and its contribution to the total noises of the differences data are analyzed. The result indicates that the noise increases linearly with the increase of the distance between the two stations in the range of 40° longitude-difference, and its increasing rate is about 0.4 nT/(°) at latitude 40°N. The example calculated at a pair of sites with longitude-difference 0.357°, shows that the noise is about one fifth of the total noises of the difference data on geomagnetic quiet-day.

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

    Science.gov (United States)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2013-04-01

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

  6. Magnetic Flux of EUV Arcade and Dimming Regions as a Relevant Parameter for Early Diagnostics of Solar Eruptions - Sources of Non-Recurrent Geomagnetic Storms and Forbush Decreases

    CERN Document Server

    Chertok, I M; Belov, A V; Abunin, A A

    2012-01-01

    This study aims at the early diagnostics of geoeffectiveness of coronal mass ejections (CMEs) from quantitative parameters of the accompanying EUV dimming and arcade events. We study events of the 23th solar cycle, in which major non-recurrent geomagnetic storms (GMS) with Dst <-100 nT are sufficiently reliably identified with their solar sources in the central part of the disk. Using the SOHO/EIT 195 A images and MDI magnetograms, we select significant dimming and arcade areas and calculate summarized unsigned magnetic fluxes in these regions at the photospheric level. The high relevance of this eruption parameter is displayed by its pronounced correlation with the Forbush decrease (FD) magnitude, which, unlike GMSs, does not depend on the sign of the Bz component but is determined by global characteristics of ICMEs. Correlations with the same magnetic flux in the solar source region are found for the GMS intensity (at the first step, without taking into account factors determining the Bz component near t...

  7. Secular variation in Western Europe during the first millennium BC New full vector data and comparison with geomagnetic models

    Science.gov (United States)

    Hervé, G.; Chauvin, A.; Lanos, P.

    2011-12-01

    Archaeological structures in Western Europe are the most-used material to estimate the secular variation of the geomagnetic field during the last millennia. However there is still a lack of data especially for archaeointensities beyond the transition BC/AD, whereas already published data suggest very strong secular variation during the first millennium BC. This study presents 37 new archaeodirections and 18 new archaeointensities from France for the last 1500 years BC. Studied materials are kilns, hearths and two sets of pottery collections. Usual rock magnetism methods have been carried out to characterize magnetic grains. Archaeodirections were obtained by thermal and alternating fields demagnetization and they were corrected for thermal remanent magnetization anisotropy effects. Archaeointensities were determined with the classical Thellier-Thellier protocol with pTRM checks and take account of anisotropy and cooling rate effects. New Bayesian Western Europe secular variation curves for archaeodirection and archaeointensity were built with this new dataset and previously published data selected following reliability criteria. New curves present small variations of inclination during the last 1500 years BC. However for declination a very sharp maximum is observed around 800-750BC. Our new high-quality data set reveals also a regular decrease of archaeointensity between 800BC and the end of the first millennium BC. Our secular variation curves for France are very coherent with predicted directions computed with ARCH3K_cst.1 constrained model (Korte et al., 2009), but we note some discrepancies for archaeointensity between data and predicted values. ARCH3K_cst.1 constrained model built with archaeomagnetic and volcanic data seems more efficient than CALS3k.4 model (Korte & Constable, 2011), which includes archaeomagnetic, volcanic and sedimentary records. This study demonstrates consequently the central part of high-quality archaeomagnetic and volcanic data in the

  8. New evidence of a fast secular variation of the geomagnetic field 1000 BCE: archaeomagnetic study of Bavarian potteries

    Science.gov (United States)

    Hervé, G.; Gilder, S.; Fassbinder, J.; Metzler-Nebelsick, C.; Schnepp, E.; Geisweid, L.; Putz, A.; Reuss, S.; Riedel, G.; Westhausen, I.; Wittenborn, F.

    2016-12-01

    This study presents new archaeointensity results obtained on 350 pottery sherds from 45 graves and pits from 12 sites around Munich (Germany). The features are dated between 1400 and 400 BCE by ceramic and metallic artifacts, radiocarbon and dendrochronology. We collected only red- or partly red-colored sherds in order to minimize mineralogical alteration during laboratory experiments. Rock magnetism analyses show that the remanent magnetization is mainly carried by titanomagnetite. Archaeointensities were determined using the Thellier-Thellier protocol with corrections of TRM anisotropy and cooling rate on one to three specimens per sherd. The experiments were completed using Triaxe and multispecimen (MSP-DSC) methods. Around 60 per cent of the sherds provide reliable results, allowing the computation of 35 mean archaeointensity values. This quadruples the number of previously published data in Western Europe. The secular variation of the geomagnetic field strength is low from 1400 to 1200 BCE with intensities close to 50 µT then the intensity increased to 70 µT around 1000-900 BCE. After a minimum 50 µT near 750 BCE, the intensity increased again to 90 µT at 650 BCE. This high secular variation rate (0.4 µT/year) is especially apparent in the sherds from a fountain dated between 750 and 650 BCE. Next, the intensity remained high until 400 BCE before rapidly decreasing to 200 BCE. As the sharp change in geomagnetic direction around 800 BCE is not contemporaneous with an intensity high, this period is probably not characterized by an archaeomagnetic jerk. The trend of secular variation with two intensity maxima is similar to the one observed in the Near East. The Virtual Axial Dipole Moments of the two regions are approximately the same after 700 BCE, but before they are systematically 1-2 × 1022 Am2 higher in the Near East. This difference may be a further proof of a geomagnetic field anomaly in this area 1000 BCE, yet there is no evidence for a geomagnetic

  9. PFISR observation of intense ion upflow fluxes associated with an SED during the 1 June 2013 geomagnetic storm

    Science.gov (United States)

    Zou, Shasha; Ridley, Aaron; Jia, Xianzhe; Boyd, Emma; Nicolls, Michael; Coster, Anthea; Thomas, Evan; Ruohoniemi, J. M.

    2017-02-01

    The Earth's ionosphere plays an important role in supplying plasma into the magnetosphere through ion upflow/outflow, particularly during periods of strong solar wind driving. An intense ion upflow flux event during the 1 June 2013 storm has been studied using observations from multiple instruments. When the open-closed field line boundary (OCB) moved into the Poker Flat incoherent scatter radar (PFISR) field of view, divergent ion fluxes were observed by PFISR with intense upflow fluxes reaching 1.9 × 1014 m-2 s-1 at 600 km altitude. Both ion and electron temperatures increased significantly within the ion upflow, and thus, this event has been classified as a type 2 upflow. We discuss factors contributing to the high electron density and intense ion upflow fluxes, including plasma temperature effect and preconditioning by storm-enhanced density (SED). Our analysis shows that the significantly enhanced electron temperature due to soft electron precipitation in the cusp can reduce the dissociative recombination rate of molecular ions above 400 km and contributed to the density increase. In addition, this intense ion upflow flux event is preconditioned by the lifted F region ionosphere due to northwestward convection flows in the SED plume. During this event, the OCB and cusp were detected by DMSP between 15 and 16 magnetic local times, unusually duskward. Results from a global magnetohydrodynamics simulation using the Space Weather Modeling Framework have been used to provide a global context for this event. This case study provides a more comprehensive mechanism for the generation of intense ion upflow fluxes observed in association with SEDs.

  10. New archaeointensity results from archaeological sites and variation of the geomagnetic field intensity for the last 7 millennia in Greece

    Science.gov (United States)

    De Marco, E.; Spatharas, V.; Gómez-Paccard, M.; Chauvin, A.; Kondopoulou, D.

    In this study six new intensity determinations are presented, obtained from five well dated archaeological sites, located in northern Greece and in Paros, Cyclades Islands. The fired structures consisted of ceramic and pottery kilns belonging to the Hellenistic, Roman and Byzantine periods. Between 8 and 21 samples of highly fired baked clays, tiles and bricks were taken, homogeneously distributed over the structures. The samples were analysed using the classical Thellier method, providing the past intensities and directions of the geomagnetic field recorded at each site. The intensity values have been corrected for anisotropy of thermal remanent magnetisation and cooling rate effects. Differences in the mean archaeointensities per site ranging from 1% to 11%, before and after TRM anisotropy and cooling rate corrections, were obtained. The new results indicate a decrease of 20% of the geomagnetic field strength in Greece, during the last four centuries BC. In order to compare our results with previously published data, a catalogue of archaeo- and palaeointensity results for the Aegean area has been established, covering the last 7 millennia. It consists of 336 data from Greece, western Turkey and Former Yugoslavia, collected from various authors. Weighting factors have been applied to these data, that then have been treated with a hierarchical Bayesian modelling, and a geomagnetic field intensity variation curve for Greece was constructed. A good agreement is observed when comparing the curve for Greece with the Bulgarian secular variation curve (SVC) for intensity. Satisfactory coincidence is also found with the archaeointensity data from Mesopotamia. Despite the presence of some time gaps, a more precise secular variation intensity curve has been constructed for Greece which, combined with a forthcoming directional SVC, will help for dating purposes.

  11. New archaeomagnetic direction results from China and their constraints on palaeosecular variation of the geomagnetic field in Eastern Asia

    Science.gov (United States)

    Cai, Shuhui; Tauxe, Lisa; Deng, Chenglong; Qin, Huafeng; Pan, Yongxin; Jin, Guiyun; Chen, Xuexiang; Chen, Wei; Xie, Fei; Zhu, Rixiang

    2016-11-01

    We carried out an archaeomagnetic directional study on 38 oriented samples (bricks and baked clays) collected from four archaeological locations at three provinces in China. The ages of our samples, spanning from ˜3000 BCE to ˜1300 CE, were constrained using a combination of archaeological context, radiocarbon dating and stratigraphic information. Rock magnetic results demonstrate that the main magnetic minerals of the studied samples are magnetite and/or hematite in single domain and superparamagnetic states. A total of 20 new reliable archaeodirectional data from 12 independent sites are obtained after thermal demagnetization experiments. These are the first set of archaeodirectional data in China produced since the 1990s. The published data are largely from the past 2 kyr and data from older time periods are rare. Our new data, especially those from period older than 3 ka, fill many gaps of the presently published dataset and will provide strong constraints on palaeosecular variation of the geomagnetic field in Eastern Asia and on the improvement of global models. Quite a few inflection points in the direction of the geomagnetic field are recorded in Eastern Asia over the past 10 kyr and some of them synchronize with the maximums or minimums of the palaeointensity. The palaeosecular variation rates are very low (based on present data distribution) before 2000 BCE and then start to increase and fluctuate afterward, which is generally consistent with the pattern of palaeointensity variations in this area.

  12. Evaluation of the Applicability of the Chapman-Miller Method on Variation of the Geomagnetic Total Intensity Field in Taiwan from 1988 to 2007

    Directory of Open Access Journals (Sweden)

    Chieh-Hung Chen

    2009-01-01

    Full Text Available The solar (S and lunar (L variations of geomagnetic fields at the horizontal (H, declination (D, and the downward vertical component data (Z are modeled by the Chap man-Miller method with four order harmonics. In this paper, we compare S and L variations of the geomagnetic total intensity field using a consistent method with 3-component data for seasonal variations (summer, winter, and equinox for three distinct phases during the years 1988 - 2007. The results show that consistency in the S and L variations for geomagnetic total intensity indicates normal stations and discrepancies are occurred due to data quality. In application, consistent results also prove that the function of the magnetometers at TW was normal and that large anomalies were certainly in existence during the Chia-Yi earthquake.

  13. Electric Utility Industry Experience with Geomagnetic Disturbances

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Electric utility industry experience with geomagnetic disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. [Oak Ridge National Lab., TN (United States); Taylor, E.R. Jr. [ABB Power Systems, Inc., Pittsburgh, PA (United States); 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.

  15. Electric utility industry experience with geomagnetic disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. (Oak Ridge National Lab., TN (United States)); Taylor, E.R. Jr. (ABB Power Systems, Inc., Pittsburgh, PA (United States)); 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.

  16. Electric utility industry experience with geomagnetic disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. (Oak Ridge National Lab., TN (United States)); Taylor, E.R. Jr. (ABB Power Systems, Inc., Pittsburgh, PA (United States)); 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.

  17. Electric utility industry experience with geomagnetic disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. [Oak Ridge National Lab., TN (United States); Taylor, E.R. Jr. [ABB Power Systems, Inc., Pittsburgh, PA (United States); 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.

  18. Improving our knowledge of the rapid geomagnetic field intensity variation observed in Europe around 800 AD

    Science.gov (United States)

    Gómez-Paccard, M.; Chauvin, A.; Lanos, P.; Dufresne, P.; Kovacheva, M.; Hill, M. J.; Beamud, E.; Gutiérrez-Lloret, S.; Cañavate, V.; Blain, S.; Bouvier, A.; Oberlin, C.; Guibert, P.; Sapin, C.; Pringent, D.

    2011-12-01

    Available European data indicate that during the past 2500 years there have been periods of rapid intensity geomagnetic fluctuations interspersed with periods of little change. The challenge now is to precisely describe these rapid changes. The aim of this study is to obtain an improved description of the sharp geomagnetic intensity change that took place in Western Europe around 800 yrs AD as well as to investigate if this peak is observed at a continental scale. For this purpose 13 precisely dated early medieval Spanish pottery fragments, 4 archeological French kilns and a 3 collections of bricks used for the construction of different historical buildings from France and with ages ranging between 330 to 1290 AD have been studied. The material collected has been dated by archeological/historical constraints together with radiocarbon,thermoluminiscence (TL) and archeomagentic analysis. From classical Thellier experiments including TRM anisotropy and cooling rate corrections upon archeointensity estimates and conducted on 164 specimens (119 of them giving reliable results) ten new high-quality mean intensities have been obtained. The new intensity data together with a selection of the most reliable data from Western Europe have been relocated to the latitude of Paris and confirm the existence of an intensity maxima of ~85 μT centred at ~850 AD and related to intensity changes up to 20 μT per century. The results also indicate that a previous abrupt intensity change (reaching a maximum value of ~ 90 μT) took place in Western Europe around 650 AD. A selection of high-quality intensity data from Bulgaria, Italy and Greece indicate a very similar intensity trend for Eastern Europe. Although available data indicate that the duration of such periods of high intensities may be of less than one century more data are needed to infer the exact duration of these maximums. A comparison between the selected data and regional and global geomagnetic field models indicates that

  19. Global changes of cosmic ray cutoff rigidities in the maximum of the geomagnetic storm of November 2003

    Science.gov (United States)

    Vernova, Elena; Tyasto, Marta; Danilova, Olga

    2017-04-01

    Vertical cosmic ray (CR) cutoff rigidities were calculated by the CR particle trajectory tracing method in the magnetic field of the Tsyganenko's disturbed magnetosphere model Ts01 for the minimum of the Dst-variation for world grid 5°x15°. The results were compared with cutoff rigidities of Shea & Smart for IGRF2000. The areas of the large differences between them are revealed.

  20. Holocene geomagnetic field variations from low latitude site: contribution from the Canary Islands

    Science.gov (United States)

    Kissel, Catherine; Laj, Carlo; Rodriguez-Gonzalez, Alejandro; Perez-Torrado, Francisco; Carrracedo, Juan-Carlos; Wandres, Camille

    2016-04-01

    Full geomagnetic vector information was retrieved from 37 lava flows (corresponding to 38 sites because one flow was sampled at two different localities) located in Tenerife and Gran Canaria (Canary Islands). Twenty-eight flows are dated between 1706 AD and about 13200 BC and one is historical. Eight other non-dated flows have stratigraphic links with the dated flows and at the end, our study allowed us to attribute to them archeomagnetic ages based on their paleomagnetic characteristics. Various mineralogical analyses were conducted, giving access to the nature and grain size of the magnetic minerals. Full stepwise (about 13 steps) thermal and AF demagnetizations were conducted on more than 400 samples to determine the paleomagnetic directions. The individual MAD values are on the average about 2° and the mean precision parameter at the flow scale (alpha95) is 4.2°. For paleointensities (PI), we performed the original Thellier and Thellier experiments with a success rate of about 65%, coupling it with the strict set of selection criteria PICRIT-03. The mean PIs at the flow level are based on 3 to 12 independent PI determinations except for one site in which only one reliable determination could be obtained. The obtained data are unique in this area over the 1000-14000 BC period and they are complementary to the dataset obtained in the Canary Islands for the last 500 years. Over the last 3 kyr, they indicate some variability in the local field intensity with a prominent PI peak centered around 600 BC and reaching 80 μT (VADM 16 x 10 ^22 Am ^2), documented by four different flows and associated to significantly easterly deviated declinations. The directional data are rather consistent with the most recent models proposed for that area but the obtained PI indicate that models largely underestimate the paleointensities. Combined with published data obtained from western Africa, Spain, Portugal, Morocco and the Azores within a 2000 km-radius around the Canary

  1. Radio and optical observations of large-scale traveling ionospheric disturbances during a strong geomagnetic storm of 6-8 April 2000

    CERN Document Server

    Afraimovich, E L; Leonovich, L A; Lesyuta, O S; Mikhalev, A V; Ashkaliev, Y F; Aushev, V M; Vodyannikov, V V; Yakovets, A F; Ashkaliev, Ya. F.

    2001-01-01

    Basic properties of the mid-latitude large-scale traveling ionospheric disturbances (LS TIDs) during the maximum phase of a strong magnetic storm of 6-8 April 2000 are shown. Total electron content (TEC) variations were studied by using data from GPS receivers located in Russia and Central Asia. The nightglow response to this storm at mesopause and termospheric altitudes was also measured by optical instruments FENIX located at the observatory of the Institute of Solar-Terrestrial Physics, (51.9 deg. N, 103.0 deg. E) and MORTI located at the observatory of the Institute of Ionosphere (43.2 deg. N, 77.0 deg. E). Observations of the O (557.7 nm, 630.0 nm, 360-410 nm, and 720-830 nm) emissions originating from atmospheric layers centered at altitudes of 90 km, 97 km, and 250 km were carried out at Irkutsk and of the O_2 (866.5 nm) emission originating from an atmospheric layer centered at altitude of 95 km was carried out at Almaty. Variations of the f_0F2 and virtual altitude of the F2 layer were measured at Al...

  2. Regulation of autonomic nervous system in space and magnetic storms

    Science.gov (United States)

    Baevsky, R. M.; Petrov, V. M.; Chernikova, A. G.

    Variations in the earth's magnetic field and magnetic storms are known to be a risk factor for the development of cardiovascular disorders. The main ``targets'' for geomagnetic perturbations are the central nervous system and the neural regulation of vascular tone and heart rate variability. This paper presents the data about effect of geomagnetic fluctuations on human body in space. As a method for research the analysis of heart rate variability was used, which allows evaluating the state of the sympathetic and parasympathetic parts of the autonomic nervous system, vasomotor center and subcortical neural centers activity. Heart rate variability data were analyzed for 30 cosmonauts at the 2-nd day of space flight on transport spaceship Soyuz (32nd orbit). There were formed three groups of cosmonauts: without magnetic storm (n=9), on a day with magnetic storm (n=12) and 1-2 days after magnetic storm (n=9). The present study was the first to demonstrate a specific impact of geomagnetic perturbations on the system of autonomic circulatory control in cosmonauts during space flight. The increasing of highest nervous centers activity was shown for group with magnetic storms, which was more significant on 1-2 days after magnetic storm. The use of discriminate analysis allowed to classify indicated three groups with 88 % precision. Canonical variables are suggested to be used as criterions for evaluation of specific and non-specific components of cardiovascular reactions to geomagnetic perturbations. The applied aspect of the findings from the present study should be emphasized. They show, in particular, the need to supplement the medical monitoring of cosmonauts with predictions of probable geomagnetic perturbations in view of the prevention of unfavorable states appearances if the adverse reactions to geomagnetic perturbations are added to the tension experienced by regulatory systems during various stresses situations (such as work in the open space).

  3. The temporal and spatial variations of low frequency geomagnetic pulsations at polar cusp and cap latitudes

    Directory of Open Access Journals (Sweden)

    J. Bitterly

    1999-06-01

    Full Text Available Geomagnetic field measurements at two Antarctic stations are compared during two weeks in the local summer (January 1-15, 1992. Low frequency (0.6-6 mHz pulsations are observed at each station near local magnetic noon. The same wave packets appear in some cases also at the other station, although with a significant attenuation, more clearly in the morning sector; the waves show a near noon reversal of the polarization sense from counter-clockwise in the morning to clockwise in the afternoon indicating a westward and an eastward propagation, respectively.

  4. Investigation of Characteristics of Large dB/dt for Geomagnetically Induced Currents

    Science.gov (United States)

    Munoz, D.; Ngwira, C.; Damas, M. C.

    2016-12-01

    When geomagnetically induced currents (GICs) flow through electrical networks, they become a potential threat for electrical power systems. Changes in the geomagnetic field (dB/dt) during severe geomagnetic disturbances are the main sources of GICs. These dB/dt phenomena were studied by selecting 24 strong geomagnetic storms with Dst ≤ - 150 nT. ACE spacecraft solar wind data: flow speed, proton density, By and Bz IMF components of the solar wind were correlated with measurements of the magnetic field detected on ground stations at different latitudes. This article reports characteristics of the solar wind during time intervals of large changes in the horizontal geomagnetic field with a threshold of dB/dt ≥ ± 20 nT/min for the 24 geomagnetic storms. The results of this investigation can help scientists to understand the mechanisms responsible for causing large magnetic field variations in order to predict and mitigate possible large events in the future, which is critical for our society that relies constantly on electricity for livelihood and security. In addition, this ongoing project will continue to investigate electron flux response before, during, and after large changes in geomagnetic field.

  5. A directional Secular Variation Curve for Greece for the last 4500 years: Comparison with regional and global geomagnetic field models

    Science.gov (United States)

    de Marco, E.; Tema, E.; Lanos, P.; Kondopoulou, D.

    2009-12-01

    A total of 64 Greek archaeomagnetic directional data have been used for the establishment of the variation of the Earth’s magnetic field in Greece over the past 4500 years. Most of the data come from archaeological material but some data from Santorini lava flows are also included. The data ages range from Minoan times (~2500 BC) up to the last century with a gap around 10th to 6th century BC. All data have been relocated to Athens (37.97° N, 23.72° E) using the virtual geomagnetic pole method. Data coming from direct measurements available in Greece for the last four centuries have been also added. The secular variation (SV) curves for declination and inclination have been obtained using hierarchical Bayesian modelling. For comparison, the dataset has been also analysed using the bi-variate moving average window technique with 150 years time window shifted by 75 years. The obtained smoothed curves accompanied by a 95 % confidence envelope are compared with archaeomagnetic data from Mediterranean area and with SV curves from nearby countries. The Greek curves have also been compared with the predictions of the SCHA.DIF.3K regional and the CALS7K and ARCH3K global geomagnetic field models. Despite the differences recognised between these models, the Greek archaeomagnetic SV curve is in reasonably good agreement with their basic trends. The proposed directional SV curve can contribute, together with the intensity SV curve previously published for Greece, to the reliable archaeomagnetic dating of Greek artefacts based on the full description of the Earth’s magnetic field (declination, inclination, intensity). It is clear that the continuous update of the dataset with new results from well-dated archaeological material will increase the precision of the SV curve, especially for the time periods poorly covered by data.

  6. Variations of Morphologic Changes induced by Tropical Storm Debby along Three Barrier Island, West-Central Florida, USA

    Science.gov (United States)

    Wang, P.; Roberts, T.

    2012-12-01

    Tropical Storm Debby generated sustained high waves and elevated water levels for nearly three days from June 24th to 26th, 2012, inducing substantial changes in beach and nearshore morphology. In addition, the storm winds and high waves approached the coast from a highly oblique angle from the south, driving substantial northward longshore sand transport, opposite to the regional net annual southward transport. A total of 145 beach and nearshore profiles along 3 adjacent barrier islands were surveyed 2 weeks before and one week after the storm impact. Overall, dune, beach, intertidal, and immediate subtidal areas suffered erosion, while deposition was measured over the nearshore bar. Beach recovery in the form of ridge and runnel development occurred as the storm energy subsided. Substantial longshore variations of storm-induced beach changes were measured, including both severe dune/beach/berm erosion and storm berm accretion, and both onshore and offshore migration of nearshore bar. Factors controlling these longshore variations include: 1) the oblique approaching of the storm forcing, 2) pre-storm beach morphology and chronic erosional or accretional trends, 3) sediment supply, and 4) tidal inlet and beach interactions. Wide spreading dune scarping occurred along the 30-km studied coast. Based on the pre- and post-storm survey data, a balanced sediment budget is obtained accounting for sand volume loss from dune, beach, intertidal, and subtidal zones, and sand gains over the nearshore bar and along the northern sections of the beach.

  7. Using “domino” model to study the secular variation of the geomagnetic dipolar moment

    Science.gov (United States)

    Duka, B.; Peqini, K.; De Santis, A.; Pavón-Carrasco, F. J.

    2015-05-01

    Aiming to understand the physical processes underneath the reversals events of geomagnetic field, different numerical models have been conceived. We considered here the so named “domino” model, an Ising-Heisenberg model of interacting magnetic macrospins aligned along a ring. This model was proposed by Mazaud and Laj (1989) and then applied by Mori et al. (2013) to study geomagnetic field reversals. The long series of the axial magnetic moment (dipolar moment or “magnetization”) generated by the “domino” model are empirically studied by varying all model parameters. We present here some results which are slightly different from those given by Mori et al. (2013), and will provide our explanation on the presence of these differences. We also define the set of parameters that supply the longest mean time between reversals. Using this set of parameters, a large number of time series of axial magnetic moment are also generated. After de-noising the fluctuation of these time series and averaging them, we compared the resulting averaged series with the series of axial dipolar magnetic moment values supplied by CALS7k.2, and CALS10k.1b models, finding similar behavior for the all time series. In a similar way, we also compared the averaged 14,000 years long series of dipolar moment with the dipolar magnetic moment obtained by the model SHA.DIF.14k.

  8. Applying "domino" model to study dipolar geomagnetic field reversals and secular variation

    Science.gov (United States)

    Peqini, Klaudio; Duka, Bejo

    2014-05-01

    Aiming to understand the physical processes underneath the reversals events of geomagnetic field, different numerical models have been conceived. We considered the so named "domino" model, an Ising-Heisenberg model of interacting magnetic spins aligned along a ring [Mazaud and Laj, EPSL, 1989; Mori et al., arXiv:1110.5062v2, 2012]. We will present here some results which are slightly different from the already published results, and will give our interpretation on the differences. Following the empirical studies of the long series of the axial magnetic moment (dipolar moment or "magnetization") generated by the model varying all model parameters, we defined the set of parameters that supply the longest mean time between reversals. Using this set of parameters, a short time series (about 10,000 years) of axial magnetic moment was generated. After de-noising the fluctuation of this time series, we compared it with the series of dipolar magnetic moment values supplied by CALS10K.1b model for the last 10000 years. We found similar behavior of the both series, even if the "domino" model could not supply a full explanation of the geomagnetic field SV. In a similar way we will compare a 14000 years long series with the dipolar magnetic moment obtained by the model SHA.DIF.14k [Pavón-Carrasco et al., EPSL, 2014].

  9. Multifractal analysis of low-latitude geomagnetic fluctuations

    Directory of Open Access Journals (Sweden)

    M. J. A. Bolzan

    2009-02-01

    Full Text Available The technique of large deviation multifractal spectrum has shown that the high-latitude (77.5° N, 69.2° W geomagnetic fluctuations can be described from direct dissipation process or loading-unloading regimes of the solar wind-magnetosphere coupling. In this paper, we analyze the H-component of low-latitude (22.4° S, 43.6° W geomagnetic field variability observed during the month of July 2000 at the Geomagnetic Observatory, Vassouras, RJ, Brazil. The variability pattern during this period is a mixture of quiet and disturbed days including the Bastille Day intense geomagnetic storm on 15 July. Due to the complexity of this data, we pursue a detailed analysis of the geomagnetic fluctuations in different time scales including a multifractal approach using the singular power spectrum deviations obtained from the wavelet transform modulus maxima (WTMM. The results suggest, as observed from high-latitude data, the occurrence of low-latitude multifractal processes driving the intermittent coupling between the solar wind-magnetosphere and geomagnetic field variations. On finer scales possible physical mechanisms in the context of nonlinear magnetosphere response are discussed.

  10. Global Electric Circuit Diurnal Variation Derived from Storm Overflight and Satellite Optical Lightning Datasets

    Science.gov (United States)

    Mach, Douglas M.; Blakeslee, R. J.; Bateman, M. J.; Bailey, J. C.

    2011-01-01

    We have combined analyses of over 1000 high altitude aircraft observations of electrified clouds with diurnal lightning statistics from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) to produce an estimate of the diurnal variation in the global electric circuit. Using basic assumptions about the mean storm currents as a function of flash rate and location, and the global electric circuit, our estimate of the current in the global electric circuit matches the Carnegie curve diurnal variation to within 4% for all but two short periods of time. The agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Mean contributions to the global electric circuit from land and ocean thunderstorms are 1.1 kA (land) and 0.7 kA (ocean). Contributions to the global electric circuit from ESCs are 0.22 kA for ocean storms and 0.04 kA for land storms. Using our analysis, the mean total conduction current for the global electric circuit is 2.0 kA.

  11. Atmospheric inputs of organic matter to a forested watershed: Variations from storm to storm over the seasons

    Science.gov (United States)

    Iavorivska, Lidiia; Boyer, Elizabeth W.; Miller, Matthew P.; Brown, Michael G.; Vasilopoulos, Terrie; Fuentes, Jose D.; Duffy, Christopher J.

    2016-12-01

    The objectives of this study were to determine the quantity and chemical composition of precipitation inputs of dissolved organic carbon (DOC) to a forested watershed; and to characterize the associated temporal variability. We sampled most precipitation that occurred from May 2012 through August 2013 at the Susquehanna Shale Hills Critical Zone Observatory (Pennsylvania, USA). Sub-event precipitation samples (159) were collected sequentially during 90 events; covering various types of synoptic meteorological conditions in all climatic seasons. Precipitation DOC concentrations and rates of wet atmospheric DOC deposition were highly variable from storm to storm, ranging from 0.3 to 5.6 mg C L-1 and from 0.5 to 32.8 mg C m-2 h-1, respectively. Seasonally, storms in spring and summer had higher concentrations of DOC and more optically active organic matter than in winter. Higher DOC concentrations resulted from weather types that favor air advection, where cold frontal systems, on average, delivered more than warm/stationary fronts and northeasters. A mixed modeling statistical approach revealed that factors related to storm properties, emission sources, and to the chemical composition of the atmosphere could explain more than 60% of the storm to storm variability in DOC concentrations. This study provided observations on changes in dissolved organic matter that can be useful in modeling of atmospheric oxidative chemistry, exploring relationships between organics and other elements of precipitation chemistry, and in considering temporal changes in ecosystem nutrient balances and microbial activity.

  12. Geomagnetism 4

    CERN Document Server

    Jacobs, John A

    2013-01-01

    Geomagnetism, Volume 4 focuses on the processes, methodologies, technologies, and approaches involved in geomagnetism, including electric fields, solar wind plasma, pulsations, and gravity waves.The selection first offers information on solar wind, magnetosphere, and the magnetopause of the Earth. Discussions focus on magnetopause structure and transfer processes, magnetosphere electric fields, geomagnetically trapped radiation, microstructure of the solar wind plasma, and hydro magnetic fluctuations and discontinuities. The text then examines geomagnetic tail, neutral upper atmosphere, and ge

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

    Science.gov (United States)

    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

  14. An electromagnetic sounding experiment in Germany using the vertical gradient of geomagnetic variations observed in a deep borehole

    Science.gov (United States)

    Schmucker, Ulrich; Spitzer, Klaus; Steveling, Erich

    2009-09-01

    We have recorded for 13 d, geomagnetic variations simultaneously on the Earth's surface and in a borehole at 832 m depth straight below, with a sampling rate of 1 Hz. In addition, geoelectric variations were observed at the same site near Bad Königshofen in Frankonia, Germany. The penetrated moderately conductive Triassic sediments lie above highly resistive Permian deposits. A presumably crystalline basement begins at 1500-1900 m depth. The purpose of the experiment is to determine the skin effect of geomagnetic variations and to derive from it the equivalent to the magnetotelluric (MT) surface impedance, using the vertical gradient (VG) method of electromagnetic (EM) sounding. In this way, we were able to reproduce all four elements of the MT impedance tensor, except for an unexplained but consistent downward shift of VG phases against MT phases by roughly 15° for the two off-diagonal elements. Hence, our tensor evaluation goes beyond the common practice, to express the skin effect by a single VG transfer function in response to a layered structure. The otherwise good agreement of VG and MT results implies that at our test site, the MT impedance tensor is largely distortion-free and that, for example, its pronounced anisotropy should be regarded as a genuine characteristic of the EM response for a laterally non-uniform or possibly anisotropic deep structure. The drilling site lies within the range of a widespread induction anomaly. We have observed the resulting variations of the vertical magnetic component at the surface and in the borehole and found them to be identical. The thus established absence of a skin effect for the vertical component allows us to treat the sedimentary layer down to the depth of the borehole instrument as a thin sheet, and the pertinent thin-sheet approximation for EM induction forms the basis of our analysis. We have derived the required estimate of conductance from the skin effect of horizontal components, noting that this estimate

  15. Analysis on the decadal scale variation of the dust storm in North China

    Institute of Scientific and Technical Information of China (English)

    KANG Dujuan; WANG Huijun

    2005-01-01

    In this paper, the temporal variation characteristics of the dust storm in North China are investigated. Based on power spectrum analysis and wavelet analysis, 1956-1970 and 1985-1999 are chosen as the high-frequency and low-frequency dust storm decades respectively. Analysis results clearly show that the spring and wintertime anomalous atmospheric circulation between these two decades are significantly different. Compared with the former decade, there are a strengthened polar vortex, enhanced westerlies near 50(N, and a weak East Asian major though in the winter of the latter decade. The north and center parts of the Siberian high and the Aleutian low become weak. The southerly and easterly wind anomalies appear over the north and east parts of China, which implies the weakening of East Asian winter monsoon. Meanwhile, northern China experiences warmer winters and wetter springs, which are in favor of the weakening of dust storm intensity in North China. There are significant out-of-phase relationships between dust frequency and wintertime westerly intensity, as well as between dust frequency and Arctic Oscillation. It is also found that the frequency of dust weather is strongly related to winter-springtime East Asian monsoon intensity.

  16. Paleosecular variations of geomagnetic field from the Last Glacial Maximum to the Holocene in the north of South China Sea

    Science.gov (United States)

    Yang, X.; Huang, W.; Liu, Q.

    2012-12-01

    The high-resolution geomagnetic field records from the Last Glacial Maximum to the Holocene, which possessed of a notable climate change, were scarce in the global area. In this abstract, two gravity piston cores ZSQD2 (114.16oE, 19.58oN, ~190 cm in length, water depth 681m) and ZSQD34 (114.74oE, 19.05oN, ~184 cm in length, water depth 1820 m), situated in the north of South China Sea, were selected to study the secular variations of geomagnetic field in this area. Radiocarbon ages of G.sacculifer suggest that the deposition rate varied with 56.1 cm/kyr and 3.7 cm/kyr during the Last Glacial and the Holocene, respectively. Rock magnetic results indicate that the pseudo-single domain magnetite with low coercivity dominate the properties of sediments. The characteristic remanent magnetization (ChRM) values are evaluated using the 5-8 AF steps when MAD values are generally <5. Constrained by the radiocarbon chronology, the secular variation curves since ~18 cal. kyr can be constructed using the ChRM directions and NRM/ARM ratios (as a proxy of relative intensity). Comparing the Holocene SV with that from terrestrial lakes in Southern China, similar shape corroborates the reliability of records and uniform pattern of non-dipole magnetic field. Two significant features on SV curves present the geomagnetic field characteristics from ~17 cal. kyr to the early Holocene. One is that the direction variations lag behind the relative intensity on the millennium time scale. Such as a major direction shift occurred around 13 cal. kyr while the relative intensity low was about 14 cal. kyr. Another feature is the fast and frequent wiggles both in direction and intensity between ~17 to ~14.5 cal. kyr. During this period, two significant negative inclination anomalies occurred at ~16.4 and ~15.4 cal. kyr associated with low intensity, respectively. Nevertheless, the corresponding declinations did not show the reversed features although they had also some slight fluctuations. The

  17. Atmospheric inputs of organic matter to a forested watershed: Variations from storm to storm over the seasons

    Science.gov (United States)

    Iavorivska , Lidiia; Boyer, Elizabeth W.; Miller, Matthew P.; Brown, Michael G.; Vasilopoulos , Terrie; Fuentes, Jose D.; Duffy, Christopher J.

    2016-01-01

    The objectives of this study were to determine the quantity and chemical composition of precipitation inputs of dissolved organic carbon (DOC) to a forested watershed; and to characterize the associated temporal variability. We sampled most precipitation that occurred from May 2012 through August 2013 at the Susquehanna Shale Hills Critical Zone Observatory (Pennsylvania, USA). Sub-event precipitation samples (159) were collected sequentially during 90 events; covering various types of synoptic meteorological conditions in all climatic seasons. Precipitation DOC concentrations and rates of wet atmospheric DOC deposition were highly variable from storm to storm, ranging from 0.3 to 5.6 mg C L−1 and from 0.5 to 32.8 mg C m−2 h−1, respectively. Seasonally, storms in spring and summer had higher concentrations of DOC and more optically active organic matter than in winter. Higher DOC concentrations resulted from weather types that favor air advection, where cold frontal systems, on average, delivered more than warm/stationary fronts and northeasters. A mixed modeling statistical approach revealed that factors related to storm properties, emission sources, and to the chemical composition of the atmosphere could explain more than 60% of the storm to storm variability in DOC concentrations. This study provided observations on changes in dissolved organic matter that can be useful in modeling of atmospheric oxidative chemistry, exploring relationships between organics and other elements of precipitation chemistry, and in considering temporal changes in ecosystem nutrient balances and microbial activity.

  18. Authigenic 10Be/9Be ratio signatures of the cosmogenic nuclide production linked to geomagnetic dipole moment variation since the Brunhes/Matuyama boundary

    Science.gov (United States)

    Thouveny, Nicolas; Bourlès, Didier L.; Valet, Jean‐Pierre; Bassinot, Franck; Ménabréaz, Lucie; Guillou, Valéry; Choy, Sandrine; Beaufort, Luc

    2016-01-01

    Abstract Geomagnetic dipole moment variations associated with polarity reversals and excursions are expressed by large changes of the cosmogenic nuclide beryllium‐10 (10Be) production rates. Authigenic 10Be/9Be ratios (proxy of atmospheric 10Be production) from oceanic cores therefore complete the classical information derived from relative paleointensity (RPI) records. This study presents new authigenic 10Be/9Be ratio results obtained from cores MD05‐2920 and MD05‐2930 collected in the west equatorial Pacific Ocean. Be ratios from cores MD05‐2920, MD05‐2930 and MD90‐0961 have been stacked and averaged. Variations of the authigenic 10Be/9Be ratio are analyzed and compared with the geomagnetic dipole low series reported from global RPI stacks. The largest 10Be overproduction episodes are related to dipole field collapses (below a threshold of 2 × 1022 Am2) associated with the Brunhes/Matuyama reversal, the Laschamp (41 ka) excursion, and the Iceland Basin event (190 ka). Other significant 10Be production peaks are correlated to geomagnetic excursions reported in literature. The record was then calibrated by using absolute dipole moment values drawn from the Geomagia and Pint paleointensity value databases. The 10Be‐derived geomagnetic dipole moment record, independent from sedimentary paleomagnetic data, covers the Brunhes‐Matuyama transition and the whole Brunhes Chron. It provides new and complementary data on the amplitude and timing of millennial‐scale geomagnetic dipole moment variations and particularly on dipole moment collapses triggering polarity instabilities. PMID:28163989

  19. Authigenic (10)Be/(9)Be ratio signatures of the cosmogenic nuclide production linked to geomagnetic dipole moment variation since the Brunhes/Matuyama boundary.

    Science.gov (United States)

    Simon, Quentin; Thouveny, Nicolas; Bourlès, Didier L; Valet, Jean-Pierre; Bassinot, Franck; Ménabréaz, Lucie; Guillou, Valéry; Choy, Sandrine; Beaufort, Luc

    2016-11-01

    Geomagnetic dipole moment variations associated with polarity reversals and excursions are expressed by large changes of the cosmogenic nuclide beryllium-10 ((10)Be) production rates. Authigenic (10)Be/(9)Be ratios (proxy of atmospheric (10)Be production) from oceanic cores therefore complete the classical information derived from relative paleointensity (RPI) records. This study presents new authigenic (10)Be/(9)Be ratio results obtained from cores MD05-2920 and MD05-2930 collected in the west equatorial Pacific Ocean. Be ratios from cores MD05-2920, MD05-2930 and MD90-0961 have been stacked and averaged. Variations of the authigenic (10)Be/(9)Be ratio are analyzed and compared with the geomagnetic dipole low series reported from global RPI stacks. The largest (10)Be overproduction episodes are related to dipole field collapses (below a threshold of 2 × 10(22) Am(2)) associated with the Brunhes/Matuyama reversal, the Laschamp (41 ka) excursion, and the Iceland Basin event (190 ka). Other significant (10)Be production peaks are correlated to geomagnetic excursions reported in literature. The record was then calibrated by using absolute dipole moment values drawn from the Geomagia and Pint paleointensity value databases. The (10)Be-derived geomagnetic dipole moment record, independent from sedimentary paleomagnetic data, covers the Brunhes-Matuyama transition and the whole Brunhes Chron. It provides new and complementary data on the amplitude and timing of millennial-scale geomagnetic dipole moment variations and particularly on dipole moment collapses triggering polarity instabilities.

  20. Thermospheric circulation model in meridian plane (I)——Storm time variations in thermal status and circulation

    Institute of Scientific and Technical Information of China (English)

    萧佐; 王劲松

    2000-01-01

    A thermospheric circulation model in meridian plane (TCMMP) is introduced and a case study on the variations in night side thermosphere caused by energy deposition in auroral oval during a single magnetic substorm is expounded. Calculations show that TCMMP can correctly reflect the thermospheric thermal status and circulation patterns during storm time and the results are in agreement with previous theoretical and observational ones. This paper and other works also show the validity of TCMMP in researches on medium and large scale changes in mid- and low latitude thermosphere. Results also support strongly some related theory about the cause of ionospheric storms, expecially the negative phase storms.

  1. Mechanisms of the outer radiation belt electron flux variation during magnetic storms

    Science.gov (United States)

    Nakamura, M.; Obara, T.; Koshiishi, H.; Koga, K.; Matsumoto, H.; Goka, T.

    2003-12-01

    We have investigated variations of the energetic electron flux (> 0.4 MeV) and the magnetic field in the outer radiation belt obtained from the Standard DOse Monitor (SDOM) and the MAgnetoMeter (MAM) of the Space Environment Data Acquisition equipment (SEDA) onboard Tsubasa (Mission Demonstration Test Satellite (MDS)-1). Since Tsubasa operates in geostationary transfer orbit (GTO) with an orbital period of 10 hours and an inclination of 28.5 degrees, it has provided a rare opportunity for directly observing near-equatorial radiation belt plasma particles and the magnetic field during magnetic storms. The decreases of the energetic electron flux during the main phase of the magnetic storms, and the subsequent recoveries and enhancements during the recovery phase in the outer radiation belt are linked respectively to typical variations of the magnetic field. At the moment that the outer radiation belt flux sharply drops during the main phase of the 17 April 2002 magnetic storm, the butterfly distribution is observed at L=5 and the magnetic equator where the magnitude of magnetic field is much smaller than the IGRF model. Calculating the drift motions of the energetic electrons in the Tyganenko 2001 magnetospheric magnetic field model, shows that the drift-shell splitting mechanism could generate the butterfly distribution due to loss of the near-equatorially mirroring electrons through dayside magnetopause boundary. We evaluate roles and contributions of the other possible mechanisms to explain the flux decreases. We discuss the three-dimensional field configuration in the magnetopause to compare with the low earth orbital observation of the outer radiation belt flux.

  2. Time-variation update for geomagnetic navigation reference map based on secular variation model of main geomagnetic field%基于主磁场长期变化模型的地磁导航基准图时变修正

    Institute of Scientific and Technical Information of China (English)

    孙渊; 张金生; 王仕成; 乔玉坤; 张盈

    2011-01-01

    Secular variation of main geomagnetic field is an important factor that influences the time-validity of geomagnetic navigation reference map. A method is proposed to update the variation using a model-predicted value. The secular variation model of main geomagnetic field is used to solve the time-variation problem of near-space geomagnetic navigation reference map. Secular variation model of the earth's main geomagnetic field is modeled based on WMM2010, and depending on this model, the secular variation model of near-space in China (30 km above sea level) is modeled. Calculated secular variation rates of geomagnetic components are used to update the time-variation. Experiment results indicate that the matching probability of updated map can reach more than 90%, and the effect is better when the time-interval is longer. The updated reference map by the secular variation model of main geomagnetic field has good adaptability.%地球主磁场长期变化是影响地磁导航基准图时效性的一个重要因素.提出一种以模型预测值对基准图进行时变修正的方法,利用主磁场长期变化模型解决临近空间地磁导航基准图的时变修正问题.基于WMM2010建立地球主磁场长期变化模型,在此基础上建立中国地区临近空间(海拔高度30 km)的主磁场长期变化模型,利用该模型计算出的地磁场分量长期变化率对基准图时变进行修正.仿真实验结果表明,修正后的地磁导航基准图的匹配概率可以达到90%以上,相比修正前有显著提高,且修正前后间隔时间越长效果越明显.利用主磁场长期变化模型修正后的地磁导航基准图具有良好的适配性.

  3. Geomagnetic field variations during the last 400 kyr in the western equatorial Pacific: Paleointensity-inclination correlation revisited

    Science.gov (United States)

    Yamazaki, T.; Kanamatsu, T.; Mizuno, S.; Hokanishi, N.; Gaffar, E. Z.

    2008-12-01

    A paleomagnetic study was conducted on four piston cores newly obtained from the West Caroline Basin in the western equatorial Pacific in order to investigate variations in paleointensity and inclination during the last 400 kyr. An inclination-intensity correlation was previously reported in this region using giant piston cores, but the quality of the paleomagnetic data of the younger end, the last ca. 300 kyr, was needed to be checked because the upper part of the giant piston cores could suffer from perturbation by oversampling. Age control is based on the oxygen-isotope ratios for one core and inter-core correlation using relative paleointensity for other cores. The mean inclinations of the four cores show negative inclination anomalies ranging from -5.2 to -11.2 degree. The western equatorial Pacific is documented as a region of a large negative inclination anomalies, and the observed values are comparable to those expected from the time-averaged field (TAF) models [Johnson and Constable, 1997; Hatakeyama and Kono, 2002]. Stacked curves of paleointensity and inclination were constructed from the four cores. It was confirmed that geomagnetic variations on the order of 10 to 100 kyrs occur in inclination as well as paleointensity. A cross-correlation analysis showed that significant in-phase correlation occurs between intensity and inclination for periods longer than about 25 kyr, and power spectra of both paleointensity and inclination variations have peaks at ~100 kyr periods. The regional paleointensity stack with higher resolution than the Sint-800 stack [Guyodo and Valet, 1999] should be useful for paleointensity-assisted chronostratigraphy.

  4. What is the function between the geomagnetic indices and the ionospheric foF2 parameter during the maximum of the #24 solar cycle at midlatitude?

    Science.gov (United States)

    Berényi, Kitti Alexandra; Kis, Árpád; Barta, Veronika

    2017-04-01

    In our study we analyzed the differences between the effect of CME-related (Si disturbance) and of HSS/CIR-related (Gs disturbance) geomagnetic storms in the ionospheric F2-layer during the maximum of the recent #24 solar cycle (2012-2015). These effects were investigated by taking into consideration the seasonal and daytime variations also. We used the ionospheric foF2 parameter from the midlatitude ionosonde of Széchenyi István Geophysical Observatory (IAGA code: NCK) in this work. A total number of 62 geomagnetic storm periods were analyzed: 21 from summer and 41 from winter time periods. In the main phase of the storms we compared the data of the foF2 parameter with the global geomagnetic Dst-, Kp- and AE-index. In summer at Noon an Si disturbance decreases the foF2 parameter (negative ionospheric storm effect), while the Gs disturbance triggers an increase (positive ionospheric storm effect) in the F2-layer parameter value as a function of geomagnetic storm magnitude. On the other hand, the Dawn data doesn't show such a reverse effect: both storm types causes decrease in the foF2 parameter value. In winter time period the Noon data presents a much more scattered behavior during Si disturbances which makes impossible to establish a trend (positive or negative) as a function of storm magnitude. At the same winter time period we can observe a clear increase in the foF2 parameter value during Gs disturbances as a function of geomagnetic storm magnitude. The response of ionospheric parameter values to a geomagnetic storm are very similar at Dawn during summer and winter: slight decrease. We can conclude that in summer the effect on ionospheric parameters of both geomagnetic storm types (i.e, Si and Gs) is more significant than in winter. Another conclusion is that while the Kp-index does not correlate well with the ionospheric parameter values, the Dst index shows a very good correlation with the ionospheric parameter values during a geomagnetic disturbance.

  5. Variations in the geomagnetic field strength in the 5th 3rd centuries BC in the eastern Mediterranean (according to narrowly dated ceramics)

    Science.gov (United States)

    Nachasova, I. E.; Burakov, K. S.; Il'Ina, T. A.

    2008-06-01

    The magnetization of ceramics from the eastern Mediterranean dated within a short period (mostly shorter than ±20 years) has been studied, which made it possible to specify the geomagnetic field variations on the time interval 5th 3rd centuries BC. The 11-year time series of the geomagnetic field strength values has been constructed. The field strength changes have been considered, which indicated that the centennial variation with a characteristic time of ˜130 years (according to the obtained data) is observed on this time interval as well as during the last two millennia. The ceramic material from the Mayskaya Gora archeological site (Taman), the preparation succession of which was established based on the shape of pottery but the problem of absolute dating was not solved, has been dated.

  6. Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk

    DEFF Research Database (Denmark)

    Olsen, Nils; Mandea, M.

    2007-01-01

    at the "virtual observatories" as well as those of the spherical harmonic expansion coefficients, we detect a secular variation impulse (an abrupt jump in the second time derivative of the magnetic field) in the CHAMP satellite data during the first months of the year 2003. The jerk occurred simultaneously...... an approach to extract satellite monthly means at a regular network of "virtual observatories" at 400 km altitude, based on CHAMP magnetic measurements. Using monthly means for 2001-2005 from those "virtual observatories" we investigate the space-time structure of the short-period variation of the Earth......'s magnetic field by means of a Spherical Harmonic Expansion, followed by a separation into external (magnetospheric) and internal part. This allows, for the first time, to study the secular variation globally and directly from satellite magnetic data. Analyzing the time series of the magnetic field...

  7. The variations of ionosphere critical frequency of E layer over the equatorial geomagnetic region in Southeast Asia

    Science.gov (United States)

    Kenpankho, Prasert; Ishii, Mamoru; Supnithi, Pornchai

    2016-07-01

    We investigate the values of the critical frequency of the ionospheric E layer, foE, obtained at Chumphon ionospheric observatory station, Thailand. For a declining phase of the solar cycle 23 during the year 2005-2008 and an inclining phase of the solar cycle 24 during the year 2009-2013, the foE data have been used to investigate the foE variations over the equatorial geomagnetic region in Southeast Asia. A comparison between the observation data and International Reference Ionosphere (IRI) 2012 model has also been investigated and studied. The results show that the foE obtained from IRI 2012 model underestimates foE from Chumphon station especially during the period of 7-11 am and after 6 pm for each day and all seasons. As the results combining with the previous investigations, we suggest that the underestimation of ionospheric foE by IRI 2012 model is helpful for the correction and improvement of IRI model in an equatorial Asia region.

  8. Possible links between long-term geomagnetic variations and whole-mantle convection processes

    NARCIS (Netherlands)

    Biggin, A.J.; Steinberger, B.; Aubert, J.; Suttie, N.; Holme, R.; Torsvik, T.H.; van der Meer, D.G.; van Hinsbergen, D.J.J.

    2012-01-01

    The Earth's internal magnetic field varies on timescales of months to billions of years. The field is generated by convection in the liquid outer core, which in turn is influenced by the heat flowing from the core into the base of the overlying mantle. Much of the magnetic field's variation is thoug

  9. Geomagnetic Diurnal Variations - Analysis in Space and Time Associated with the 2011 off the Pacific Coast of Tohoku Earthquake (Mw9.0)

    Science.gov (United States)

    Hattori, Katsumi; Han, Peng

    2017-04-01

    Recent studies have reported unusual behaviors of geomagnetic diurnal variation (GDV) in the vertical component prior to the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0). To make a better understanding of this phenomenon, time-spatial analysis of GDV has been applied in this study. Geomagnetic data of long term observations at 17 stations in Japan have been analyzed using the same method in Han et al. 2015. Ratios of diurnal variation range between the target station and the reference station KAK have been computed. After removing seasonal variations revealed by wavelet transform analysis, the 15-day mean values of the ratios in the vertical component shows a clear anomaly exceeding the statistical threshold about 2 months before the mega event in both ESA and MIZ stations in the Tohoku Region. Similar results could not be found in other regions of Japan. Spatial distributions of the ratios show a good agreement between the location of the anomalies and the epicenter of Mw 9.0 earthquake. These time-spatial results seem to be consistent with independent results obtained from other observations such as radon density, seismicity, and GPS displacements, which suggest the geomagnetic data might be useful in earthquake monitoring and disaster mitigation.

  10. Variations in spectroscopic characteristics and disinfection byproduct formation potentials of dissolved organic matter for two contrasting storm events

    Science.gov (United States)

    Nguyen, Hang Vo-Minh; Lee, Mi-Hee; Hur, Jin; Schlautman, Mark A.

    2013-02-01

    SummaryChanges in disinfection byproduct (DBP) precursors during storm events have not been intensively studied to date despite their dramatic impact on downstream drinking water supplies. For this study, variations in dissolved organic matter (DOM) spectroscopic properties and DBP formation potentials (DBPFPs), and the correlations among these various parameters, were investigated in river water samples collected under two contrasting storm event conditions (a strong summer storm versus a weak fall event). Fluorescence excitation-emission matrices (EEMs) combined with parallel factor analysis revealed that a combination of two humic-like components (C1 and C2) dominated the EEM data of the storm samples. Measured DOM characteristics and DBPFPs varied over a wider range during the more intense summer storm, exhibiting higher values of specific ultraviolet absorbance and C1/C2 ratio at high flow conditions. Variations in the fluorescence index were less pronounced during the two storm events. The spectroscopic changes were well explained by the input of terrestrial DOM sources from the surrounding catchments during the storms. Different trends of the formation potentials for trihalomethanes and haloacetic acids on the recession limb of the hydrographs suggest that the structures responsible for DBP precursors during storm events may not be the same for the two classes of DBPs. The ultraviolet light-absorbing moieties in DOM appear to play major roles in generating DBPs, as evidenced by their strong positive correlations with DBPFPs. Higher correlations with DBPFP for C1 versus C2 suggest that humic-like substances associated with more aromatic and condensed structures have a greater proclivity to generate DBP upon chlorination.

  11. Assessment of Vegetation Variation on Primarily Creation Zones of the Dust Storms Around the Euphrates Using Remote Sensing Images

    Directory of Open Access Journals (Sweden)

    Jamil Amanollahi

    2012-06-01

    Full Text Available Recently, period frequency and effect domain of the dust storms that enter Iran from Iraq have increased. In this study, in addition to detecting the creation zones of the dust storms, the effect of vegetation cover variation on their creation was investigated using remote sensing. Moderate resolution image Spectroradiometer (MODIS and Landsat Thematic Mapper (TM5 have been utilized to identify the primarily creation zones of the dust storms and to assess the vegetation cover variation, respectively. Vegetation cover variation was studied using Normalized Differences Vegetation Index (NDVI obtained from band 3 and band 4 of the Landsate satellite. The results showed that the surrounding area of the Euphrates in Syria, the desert in the vicinity of this river in Iraq, including the deserts of Alanbar Province, and the north deserts of Saudi Arabia are the primarily creation zones of the dust storms entering west and south west of Iran. The results of NDVI showed that excluding the deserts in the border of Syria and Iraq, the area with very weak vegetation cover have increased between 2.44% and 20.65% from 1991 to 2009. In the meanwhile, the retention pound surface areas in the south deserts of Syria as well as the deserts in its border with Iraq have decreased 6320 and 4397 hectares, respectively. As it can be concluded from the findings, one of the main environmental parameters initiating these dust storms is the decrease in the vegetation cover in their primarily creation zones.

  12. Paleomagnetic secular variation study of Ar-Ar dated lavas flows from Tacambaro area (Central Mexico): Possible evidence of Intra-Jaramillo geomagnetic excursion in volcanic rocks

    Science.gov (United States)

    Peña, Rafael Maciel; Goguitchaichvili, Avto; Guilbaud, Marie-Noëlle; Martínez, Vicente Carlos Ruiz; Rathert, Manuel Calvo; Siebe, Claus; Reyes, Bertha Aguilar; Morales, Juan

    2014-04-01

    More than 350 oriented paleomagnetic cores were obtained for rock-magnetic and paleomagnetic analysis from radiometrically dated (40Ar-39Ar) magmatic rocks occurring in the southern segment (Jorullo and Tacámbaro areas) of the Michoacán-Guanajuato Volcanic Field in the Trans-Mexican Volcanic Belt. Most of the lavas (37) stem from monogenetic volcanoes dated at less than 4 Ma. Two additional sites were sampled from the plutonic basement dated at 33-30 Ma. Primary remanences carried by low-Ti titanomagnetites allowed to determining 34 reliable site-mean directions of mostly normal (27) but also reversed (7) polarities. The mean directions of these two populations are antipodal, and suggest neither major vertical-axis rotations with respect to the North America craton nor tilting in the region for the last 4 Ma (rotation and flattening of the inclination parameters being less than -5.9 ± 3.8 and 0.1 ± 3.9, respectively). The corresponding paleomagnetic pole obtained for Pliocene-Pleistocene times is PLAT = 83.4°, PLON = 2.4° (N = 32, A95 = 2.7°). Virtual geomagnetic poles also contribute to the time averaged field global database and to the paleosecular variation (PSV) investigations at low latitudes from lavas for the last 5 Ma, showing a geomagnetic dispersion value that is in agreement with available PSV models. When comparing the magnetic polarities and corresponding radiometric ages of the studied sites with the Cenozoic geomagnetic polarity time scale (GPTS), a good correlation is observable. This finding underscores the suitability of data obtained on lavas in Central Mexico for contributing to the GPTS. Furthermore, the detection of short-lived geomagnetic features seems possible, since the possible evidence of Intra-Jaramillo geomagnetic excursion could be documented for the first time in these volcanic rocks.

  13. Observations of Deep Ionospheric F-Region Density Depletions with FPMU Instrumentation and Their Relationship with the Global Dynamics of the June 22-23, 2015 Geomagnetic Storm

    Science.gov (United States)

    Coffey, Victoria; Sazykin, Stan; Chandler, Michael O.; Hairston, Marc; Minow, Joseph I.; Anderson, Brian

    2017-01-01

    The magnetic storm that commenced on June 22, 2015 was one of the largest storms in the current solar cycle. During this event, ionospheric F-region density measurements from the Floating Potential Measurement Unit (FPMU) on board the International Space Station (ISS) show dramatic depletions in the post-sunset (nighttime) local time sector at equatorial latitudes starting in the main phase of the storm and persisting on several subsequent orbits into the next day. Putting these low-latitude measurements in context with the global dynamics of the storm, we will present results from simulations and observations in our efforts to better understand the effects of this storm on the different regions of the coupled ionosphere-magnetosphere. The consequences of the magnetospheric penetration electric field and their role in the occurrence of these equatorial spread F observations will be investigated through the results of the SAMI3-RCM numerical model, a coupled ionosphere-magnetosphere model with self-consistent large-scale electrodynamics. Specifically, we will investigate the transient signatures of the interplanetary magnetic field component, Bz, and its role in driving the global convection electric field and ionospheric density redistribution. Lastly, measurements from the AMPERE Birkeland currents, DMSP drift velocities and the particle flux dropouts observed from the Magnetospheric Multiscale Mission (MMS) will be correlated with the FPMU density depletions and each other. Together these observations and simulation results will be assembled to provide each region's context to the global dynamics and time evolution of the storm.

  14. Influence of magnetospheric inputs definition on modeling of ionospheric storms

    Science.gov (United States)

    Tashchilin, A. V.; Romanova, E. B.; Kurkin, V. I.

    Usually for numerical modeling of ionospheric storms corresponding empirical models specify parameters of neutral atmosphere and magnetosphere. Statistical kind of these models renders them impractical for simulation of the individual storm. Therefore one has to correct the empirical models using various additional speculations. The influence of magnetospheric inputs such as distributions of electric potential, number and energy fluxes of the precipitating electrons on the results of the ionospheric storm simulations has been investigated in this work. With this aim for the strong geomagnetic storm on September 25, 1998 hour global distributions of those magnetospheric inputs from 20 to 27 September were calculated by the magnetogram inversion technique (MIT). Then with the help of 3-D ionospheric model two variants of ionospheric response to this magnetic storm were simulated using MIT data and empirical models of the electric fields (Sojka et al., 1986) and electron precipitations (Hardy et al., 1985). The comparison of the received results showed that for high-latitude and subauroral stations the daily variations of electron density calculated with MIT data are more close to observations than those of empirical models. In addition using of the MIT data allows revealing some peculiarities in the daily variations of electron density during strong geomagnetic storm. References Sojka J.J., Rasmussen C.E., Schunk R.W. J.Geophys.Res., 1986, N10, p.11281. Hardy D.A., Gussenhoven M.S., Holeman E.A. J.Geophys.Res., 1985, N5, p.4229.

  15. Intensity variation of the geomagnetic field in Mesoamerica during the last 3500 years

    Science.gov (United States)

    Morales, J.; Gogichaisvili, A.

    2009-05-01

    After Nagata's and Bucha's pioneering works in Mesoamerica in the 60th's and 70th's a gap in archeointensity studies in the region seems to be opened, in spite of the abundant well known archeological vestiges available in Mexico. Aimed to improve the insipient reference curve for Mesoamerica, and to contribute to the global intensity database, we present latest archeointensity determinations obtained from oldest Western Mesoamerican archaeological deposits, as well as from pre-Columbian Central and Eastern Mexican archaeological sites. Although still not enough in number to define a variation curve for the region, they outline a tendency that differs to that of model predictions based on previous data.

  16. Variations in the geomagnetic and gravitational background associated with two strong earthquakes of the May 2012 sequence in the Po Valley Plain (Italy).

    Science.gov (United States)

    Straser, Valentino

    2013-04-01

    Reawakening of seismic activity in the Emilian Po Valley Plain (Italy) resulted in 2,492 earthquakes over five and a half months: 2,270 with M4.0, 27 con 4.0= 7. The mainshock was recorded during the night of 20 May 2012, at 04:03:52 Italian time (02:03:52 UTC) with epicentre in Finale Emilia, at a depth of 6.3km, by the Italian National Institute of Geophysics and Vulcanology (INGV). A long sequence of telluric shocks occurred in the same seismic district in the areas between the provinces of Modena, Ferrara, Mantua, Reggio Emilia, Bologna and Rovigo. In addition to the general devastation plus damage to civil and industrial buildings and the historical heritage, the earthquakes resulted in a total of 27 victims. Concomitant with the two strongest quakes, recorded on 20 and 29 May 2012, respectively, as in the case of others, variations were noted in the geomagnetic background by the LTPA monitoring station in Rome (Italy). The geomagnetic background variations were associated with the appearance of radio-anomalies in a frequency range from 0.1 to 3.0Hz, as well as gravimetric variations found around 60km from the epicentre. The peak accelerations, detected in correspondence with the strongest shocks on 20 and 29 May 2012, were respectively 0.31g and 0.29g. The appearance of the radio-anomalies coincided, from a temporal point of view, with average gravimetric variations of approximately 30µGal around the epicentre areas, concurrent with the mainshock. In this study, both the appearance of radio-anomalies and the gravitational variations recorded before strong earthquakes were related to the dynamics of the fault and a progressive reduction in granulometry in the core of the fracture, until the point of dislocation was reached. The intense friction in the fault and the damping factors produced before the shock are hypothesized as being proportional to the number of radio-anomalies measured. The radio anomaly is an unknown radio emission that has no

  17. Paleomagnetism and 40Ar/39Ar geochronology of the Plio-Pleistocene Boring Volcanic Field: Implications for the geomagnetic polarity time scale and paleosecular variation

    Science.gov (United States)

    Hagstrum, Jonathan T.; Fleck, Robert J.; Evarts, Russell C.; Calvert, Andrew T.

    2017-01-01

    Paleomagnetic directions and 40Ar/39Ar ages have been determined for samples of lava flows from the same outcrops, where possible, for 84 eruptive units ranging in age from 3200 ka to 60 ka within the Boring Volcanic Field (BVF) of the Pacific Northwest, USA. This study expands upon our previous results for the BVF, and compares the combined results with the current geomagnetic polarity time scale (GPTS). Lava flows with transitional directions were found within the BVF at the Matuyama-Brunhes and Jaramillo-Matuyama polarity boundaries, and replicate ages corresponding to these and other boundaries have been newly ascertained. Although the BVF data generally agree with GPTS chronozone boundaries, they indicate that onset of the Gauss-Matuyama transition and Olduvai subchron occurred significantly earlier than given in the current time scale calibration. Additional comparisons show that the BVF results are consistent with recent statistical models of geomagnetic paleosecular variation.

  18. Assessment of Modeling Capability for Reproducing Storm Impacts on TEC

    Science.gov (United States)

    Shim, J. S.; Kuznetsova, M. M.; Rastaetter, L.; Bilitza, D.; Codrescu, M.; Coster, A. J.; Emery, B. A.; Foerster, M.; Foster, B.; Fuller-Rowell, T. J.; Huba, J. D.; Goncharenko, L. P.; Mannucci, A. J.; Namgaladze, A. A.; Pi, X.; Prokhorov, B. E.; Ridley, A. J.; Scherliess, L.; Schunk, R. W.; Sojka, J. J.; Zhu, L.

    2014-12-01

    During geomagnetic storm, the energy transfer from solar wind to magnetosphere-ionosphere system adversely affects the communication and navigation systems. Quantifying storm impacts on TEC (Total Electron Content) and assessment of modeling capability of reproducing storm impacts on TEC are of importance to specifying and forecasting space weather. In order to quantify storm impacts on TEC, we considered several parameters: TEC changes compared to quiet time (the day before storm), TEC difference between 24-hour intervals, and maximum increase/decrease during the storm. We investigated the spatial and temporal variations of the parameters during the 2006 AGU storm event (14-15 Dec. 2006) using ground-based GPS TEC measurements in the selected 5 degree eight longitude sectors. The latitudinal variations were also studied in two longitude sectors among the eight sectors where data coverage is relatively better. We obtained modeled TEC from various ionosphere/thermosphere (IT) models. The parameters from the models were compared with each other and with the observed values. We quantified performance of the models in reproducing the TEC variations during the storm using skill scores. This study has been supported by the Community Coordinated Modeling Center (CCMC) at the Goddard Space Flight Center. Model outputs and observational data used for the study will be permanently posted at the CCMC website (http://ccmc.gsfc.nasa.gov) for the space science communities to use.

  19. Effect of Interplanetary Magnetic Field and Disturb Storm Time on H Component

    Indian Academy of Sciences (India)

    Rajni Devi; Smita Dubey; Shailendra Saini; Babita Devi; Ajay Dhar; S. K. Vijay; A. K. Gwal

    2008-03-01

    A fluxgate digital magnetometer is used to study the variation of magnitude of H component during geomagnetic storm events of April, July and November 2004 at southern subauroral localized region at “MAITRI” (geom. lat. 62°S, long. 52.8°E). We also study the effect of vertical component of interplanetary magnetic field (IMF) on the variation of the magnitude of H component during storm time of April, July and November 2004. Results show that before sudden storm commencement (SSC) time magnitude ofHcomponent and IMF showsmooth variation but after SSC of first storm of 22 July 2004, the magnitude of the H component shows fluctuations and at 09:00 UT it increases, but during second storm of 24 July 2004, the magnitude of H component indicates large fluctuations and it increases rapidly at 04:00 UT.

  20. Prospect of Using Numerical Dynamo Model for Prediction of Geomagnetic Secular Variation

    Science.gov (United States)

    Kuang, Weijia; Tangborn, Andrew

    2003-01-01

    Modeling of the Earth's core has reached a level of maturity to where the incorporation of observations into the simulations through data assimilation has become feasible. Data assimilation is a method by which observations of a system are combined with a model output (or forecast) to obtain a best guess of the state of the system, called the analysis. The analysis is then used as an initial condition for the next forecast. By doing assimilation, not only we shall be able to predict partially secular variation of the core field, we could also use observations to further our understanding of dynamical states in the Earth's core. One of the first steps in the development of an assimilation system is a comparison between the observations and the model solution. The highly turbulent nature of core dynamics, along with the absence of any regular external forcing and constraint (which occurs in atmospheric dynamics, for example) means that short time comparisons (approx. 1000 years) cannot be made between model and observations. In order to make sensible comparisons, a direct insertion assimilation method has been implemented. In this approach, magnetic field observations at the Earth's surface have been substituted into the numerical model, such that the ratio of the multiple components and the dipole component from observation is adjusted at the core-mantle boundary and extended to the interior of the core, while the total magnetic energy remains unchanged. This adjusted magnetic field is then used as the initial field for a new simulation. In this way, a time tugged simulation is created which can then be compared directly with observations. We present numerical solutions with and without data insertion and discuss their implications for the development of a more rigorous assimilation system.

  1. Spatial variations of storm runoff pollution and their correlation with land-use in a rapidly urbanizing catchment in China.

    Science.gov (United States)

    Qin, Hua-Peng; Khu, Soon-Thiam; Yu, Xiang-Ying

    2010-09-15

    The composition of land use for a rapidly urbanizing catchment is usually heterogeneous, and this may result in significant spatial variations of storm runoff pollution and increase the difficulties of water quality management. The Shiyan Reservoir catchment, a typical rapidly urbanizing area in China, is chosen as a study area, and temporary monitoring sites were set at the downstream of its 6 sub-catchments to synchronously measure rainfall, runoff and water quality during 4 storm events in 2007 and 2009. Due to relatively low frequency monitoring, the IHACRES and exponential pollutant wash-off simulation models are used to interpolate the measured data to compensate for data insufficiency. Three indicators, event pollutant loads per unit area (EPL), event mean concentration (EMC) and pollutant loads transported by the first 50% of runoff volume (FF50), were used to describe the runoff pollution for different pollutants in each sub-catchment during the storm events, and the correlations between runoff pollution spatial variations and land-use patterns were tested by Spearman's rank correlation analysis. The results indicated that similar spatial variation trends were found for different pollutants (EPL or EMC) in light storm events, which strongly correlate with the proportion of residential land use; however, they have different trends in heavy storm events, which correlate with not only the residential land use, but also agricultural and bare land use. And some pairs of pollutants (such as COD/BOD, NH(3)-N/TN) might have the similar source because they have strong or moderate positive spatial correlation. Moreover, the first flush intensity (FF50) varies with impervious land areas and different interception ratio of initial storm runoff volume should be adopted in different sub-catchments. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Geomagnetic Observations and Models

    CERN Document Server

    Mandea, Mioara

    2011-01-01

    This volume provides comprehensive and authoritative coverage of all the main areas linked to geomagnetic field observation, from instrumentation to methodology, on ground or near-Earth. Efforts are also focused on a 21st century e-Science approach to open access to all geomagnetic data, but also to the data preservation, data discovery, data rescue, and capacity building. Finally, modeling magnetic fields with different internal origins, with their variation in space and time, is an attempt to draw together into one place the traditional work in producing models as IGRF or describing the magn

  3. Geomagnetism applications

    Science.gov (United States)

    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.

  4. Methodology for simulation of geomagnetically induced currents in power systems

    Directory of Open Access Journals (Sweden)

    Boteler David

    2014-07-01

    Full Text Available To assess the geomagnetic hazard to power systems it is useful to be able to simulate the geomagnetically induced currents (GIC that are produced during major geomagnetic disturbances. This paper examines the methodology used in power system analysis and shows how it can be applied to modelling GIC. Electric fields in the area of the power network are used to determine the voltage sources or equivalent current sources in the transmission lines. The power network can be described by a mesh impedance matrix which is combined with the voltage sources to calculate the GIC in each loop. Alternatively the power network can be described by a nodal admittance matrix which is combined with the sum of current sources into each node to calculate the nodal voltages which are then used to calculate the GIC in the transmission lines and GIC flowing to ground at each substation. Practical calculations can be made by superposition of results calculated separately for northward and eastward electric fields. This can be done using magnetic data from a single observatory to calculate an electric field that is a uniform approximation of the field over the area of the power system. It is also shown how the superposition of results can be extended to use data from two observatories: approximating the electric field by a linear variation between the two observatory locations. These calculations provide an efficient method for simulating the GIC that would be produced by historically significant geomagnetic storm events.

  5. Origin-Dependent Variations in the Atmospheric Microbiome Community in Eastern Mediterranean Dust Storms.

    Science.gov (United States)

    Gat, Daniella; Mazar, Yinon; Cytryn, Eddie; Rudich, Yinon

    2017-06-20

    Microorganisms carried by dust storms are transported through the atmosphere and may affect human health and the functionality of microbial communities in various environments. Characterizing the dust-borne microbiome in dust storms of different origins or that followed different trajectories provides valuable data to improve our understanding of global health and environmental impacts. We present a comparative study on the diversity of dust-borne bacterial communities in dust storms from three distinct origins (North Africa, Syria and Saudi Arabia) and compare them with local bacterial communities sampled on clear days, all collected at a single location: Rehovot, Israel. Storms from different dust origins exhibited distinct bacterial communities, with signature bacterial taxa. Dust storms were characterized by a lower abundance of selected antibiotic resistance genes (ARGs) compared with ambient dust, asserting that the origin of these genes is local and possibly anthropogenic. With the progression of the storm, the storm-borne bacterial community showed increasing resemblance to ambient dust, suggesting mixing with local dust. These results show, for the first time, that dust storms from different sources display distinct bacterial communities, suggesting possible diverse effects on the environment and public health.

  6. Geomagnetically trapped, albedo and solar energetic particles: trajectory analysis and flux reconstruction with PAMELA

    CERN Document Server

    Bruno, A; Barbarino, G C; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; Christian, E C; De Donato, C; de Nolfo, G A; De Santis, C; De Simone, N; Di Felice, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mergé, M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Ryan, J M; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stochaj, S; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G I; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N

    2016-01-01

    The PAMELA satellite experiment is providing comprehensive observations of the interplanetary and magnetospheric radiation in the near-Earth environment. Thanks to its identification capabilities and the semi-polar orbit, PAMELA is able to precisely measure the energetic spectra and the angular distributions of the different cosmic-ray populations over a wide latitude region, including geomagnetically trapped and albedo particles. Its observations comprise the solar energetic particle events between solar cycles 23 and 24, and the geomagnetic cutoff variations during magnetospheric storms. PAMELA's measurements are supported by an accurate analysis of particle trajectories in the Earth's magnetosphere based on a realistic geomagnetic field modeling, which allows the classification of particle populations of different origin and the investigation of the asymptotic directions of arrival.

  7. An Ensemble Algorithm Based Component for Geomagnetic Data Assimilation

    Directory of Open Access Journals (Sweden)

    Zhibin Sun and Weijia Kuang

    2015-01-01

    Full Text Available Geomagnetic data assimilation is one of the most recent developments in geomagnetic studies. It combines geodynamo model outputs and surface geomagnetic observations to provide more accurate estimates of the core dynamic state and provide accurate geomagnetic secular variation forecasting. To facilitate geomagnetic data assimilation studies, we develop a stand-alone data assimilation component for the geomagnetic community. This component is used to calculate the forecast error covariance matrices and the gain matrix from a given geodynamo solution, which can then be used for sequential geomagnetic data assimilation. This component is very flexible and can be executed independently. It can also be easily integrated with arbitrary dynamo models.

  8. Recent geomagnetic secular variation from Swarm and ground observatories as estimated in the CHAOS-6 geomagnetic field model

    DEFF Research Database (Denmark)

    Finlay, Chris; Olsen, Nils; Kotsiaros, Stavros

    2016-01-01

    , under the region of northern South America, and at high northern latitudes under Alaska and Siberia. Surprisingly, there is also evidence for significant SA in the central Pacific region, for example near Hawaii where radial field SA is observed on either side of a jerk in 2014. On the other hand...... of the Earth's magnetic field between 1999.0 and 2016.5. We present details of the secular variation (SV) and secular acceleration (SA) from CHAOS-6 at Earth's surface and downward continued to the core surface. At Earth's surface, we find evidence for positive acceleration of the field intensity in 2015 over......, jets at low latitudes, for example close to 40 degrees W, that may be responsible for localized SA oscillations. In addition to scalar data from Orsted, CHAMP, SAC-C and Swarm, and vector data from Orsted, CHAMP and Swarm, CHAOS-6 benefits from the inclusion of along-track differences of scalar...

  9. The Egyptian geomagnetic reference field to the Epoch, 2010.0

    Directory of Open Access Journals (Sweden)

    H.A. Deebes

    2017-06-01

    The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF 2010 is indicated.

  10. New archeointensity data from French Early Medieval pottery production (6th-10th century AD). Tracing 1500 years of geomagnetic field intensity variations in Western Europe

    Science.gov (United States)

    Genevey, Agnès; Gallet, Yves; Jesset, Sébastien; Thébault, Erwan; Bouillon, Jérôme; Lefèvre, Annie; Le Goff, Maxime

    2016-08-01

    Nineteen new archeointensity results were obtained from the analysis of groups of French pottery fragments dated to the Early Middle Ages (6th to 10th centuries AD). They are from several medieval ceramic production sites, excavated mainly in Saran (Central France), and their precise dating was established based on typo-chronological characteristics. Intensity measurements were performed using the Triaxe protocol, which takes into account the effects on the intensity determinations of both thermoremanent magnetization anisotropy and cooling rate. Intensity analyses were also carried out on modern pottery produced at Saran during an experimental firing. The results show very good agreement with the geomagnetic field intensity directly measured inside and around the kiln, thus reasserting the reliability of the Triaxe protocol and the relevance of the quality criteria used. They further demonstrate the potential of the Saran pottery production for archeomagnetism. The new archeointensity results allow a precise and coherent description of the geomagnetic field intensity variations in Western Europe during the Early Medieval period, which was until now poorly documented. They show a significant increase in intensity during the 6th century AD, high intensity values from the 7th to the 9th century, with a minimum of small amplitude at the transition between the 7th and the 8th centuries and finally an important decrease until the beginning of the 11th century. Together with published intensity results available within a radius of 700 km around Paris, the new data were used to compute a master curve of the Western European geomagnetic intensity variations over the past 1500 years. This curve clearly exhibits five intensity maxima: at the transition between the 6th and 7th century AD, at the middle of the 9th century, during the 12th century, in the second part of the 14th century and at the very beginning of the 17th century AD. Some of these peaks are smoothed, or

  11. Evaluation of super intense geomagnetic storms and related structures of the interplanetary medium through the observation of cosmic rays of high energy surface; Analise de tempestades geomagneticas super intensas e de estruturas do meio interplanetario relacionadas, atraves da observacao de raios cosmicos de superficie de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Savian, Jairo Francisco; Schuch, Nelson J., E-mail: savian@lacesm.ufsm.br, E-mail: njschuch@lacesm.ufsm.br [Centro Regional Sul de Pesquisas Espaciais - CRSPE/INPE-MCT, Santa Maria, RS (Brazil); Silva, Marlos Rockenbach da; Lago, Alisson dal; Gonzalez, Walter Demetrio, E-mail: marlos@dge.inpe.br, E-mail: dallago@dge.inpe.br, E-mail: gonzalez@dge.inpe.br [Instituto Nacional de Pesquisas Espaciais - INPE-MCT, Sao Jose dos Campos, SP (Brazil); Munakata, Kazuoki [Physics Department, Shinshu University, Matsumoto (Japan)

    2005-04-15

    It is believed that the physical mechanism responsible for the transference of energy from the solar wind to the Earth magnetosphere is the reconnection between the interplanetary magnetic field and the terrestrial magnetic field (Tsurutani and Gonzalez, 1997). The necessary criterion for a intense geomagnetic storms to occur, Dst < -100nT, is the existence of a dawn-dusk interplanetary electric field larger than 5 mV/m, for a period larger than 3 hours. Cosmic rays have been studied as a natural phenomenon that can tell much about both Earth's environment in space and distant astrophysical processes (Jokipii, 2000). A solar disturbance propagating away from the Sun affects the pre-existing population of galactic cosmic rays in a number of ways. The most famous one is known as the 'Forbush decrease', which is a suppression of ground cosmic-ray counts observed during geomagnetic disturbances. The objective of this work is to study the response of the Southern Space Observatory ground Muon Telescope observations, installed in Sao Martinho da Serra, RS, Brazil, to 3 super intense geomagnetic storms, combining observation provided by L1 satellites and ground detectors. (author)

  12. Thermosphere variation at different altitudes over the northern polar cap during magnetic storms

    Science.gov (United States)

    Huang, Yanshi; Wu, Qian; Huang, Cheryl Y.; Su, Yi-Jiun

    2016-08-01

    In this study, we report observations and simulation results of heated neutrals at various altitudes inside the polar cap during two magnetic storms in January 2005. The Poynting flux measurements from the Defense Meteorological Satellite Program (DMSP) satellites show enhanced energy input in the polar cap during the storm main phase, which is underestimated in the TIE-GCM simulation. Neutral temperature measurements at 250 km from the ground-based Fabry-Perot Interferometer (FPI) at Resolute Bay are presented, along with the neutral density observations at 360 km and 470 km from Challenging Minisatellite Payload (CHAMP) and the Gravity Recovery and Climate Experiment (GRACE) satellites, respectively. These data have been analyzed to demonstrate the altitudinal dependence of neutral response to the storm energy input. By comparing the TIE-GCM simulation results and the observations, we demonstrate that Poynting fluxes as well as the thermosphere response were underestimated in the model. The simulated neutral temperature at Resolute Bay increases by approximately 260° and 280° K for the two events, respectively, much lower than the observed temperature enhancements of 750° and 900° K. Neutral density enhancements with more than 30% increase over the background density were also observed at polar latitudes, with no clear distinction between the auroral zone and polar cap. All measurements indicate enhancements at high latitudes poleward of 80° magnetic latitude (MLAT) implying that substantial heating can occur within the polar cap during storms.

  13. Thyroid storm

    Science.gov (United States)

    Thyrotoxic storm; Hyperthyroid storm; Accelerated hyperthyroidism; Thyroid crisis; Thyrotoxicosis - thyroid storm ... Thyroid storm occurs due to a major stress such as trauma, heart attack , or infection. In rare ...

  14. Mechanisms controlling the spatial structure of midlatitude storm tracks and their variation under global warming

    Science.gov (United States)

    Kaspi, Y.; Tamarin, T.

    2016-12-01

    The Atlantic and Pacific storm tracks in the northern hemisphere are characterized by a downstream poleward deflection, which has important consequences for the distribution of heat, wind and precipitation in the midlatitudes. In this study, the spatial structure of the storm tracks is examined by tracking transient cyclonic eddies in an idealized GCM with a localized ocean heat flux. The localized atmospheric response is decomposed in terms of a time-zonal mean background flow, a stationary wave and a transient eddy field. The Lagrangian tracks are used to construct cyclone composites and perform a spatially varying PV budget. Three distinct mechanisms that contribute to the poleward tilt emerge: transient nonlinear advection, latent heat release and stationary advection. The downstream evolution of the PV composites shows the different role played by the stationary wave in each region. Our results imply that in the region where the tilt is maximized, all three mechanisms contribute to the poleward propagation of the low level PV anomaly associated with cyclones. Upstream of that region, the stationary wave is opposing the former two and the poleward tendency is therefore reduced. Through repeated experiments with enhanced strength of the heating source, it is shown that the poleward deflection of the storms enhances when the amplitude of the stationary wave increases. For a global warming scenario, we find that poleward deflection due to transient nonlinear advection and latent heating will strengthen, meaning that the poleward motion of individual cyclones increases with increasing global mean temperatures. Our results imply that for a 4 K rise in the global mean surface temperature, the averaged poleward drift of cyclones will increase by approximately 1 degree of latitude. This will have significant impact on midlatitude climate, and implies that localized storm tracks, such as the Atlantic and Pacific storm tracks, will exhibit a more poleward deflected shape

  15. The variation in the magnetic fluctuation anisotropy across the front boundaries of magnetic clouds and its geomagnetic response

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A statistical study of magnetic fluctuations near the front boundaries of magnetic clouds is approached with the method of Minimum Variance Analysis, based on the data of Imp8 and Wind spacecraft. New discoveries are that (1) fluctuation anisotropy tends to increase across the front boundaries of magnetic clouds; (2) there is a good correlation between the fluctuation anisotropy and the geomagnetic activity indices; and (3) in some cases, although there is southward field component immediately after the front boundary, Kp index descends (or Dst index ascends) with a corresponding decrease of the fluctuation anisotropy; in other cases with no distinct southward field component, Kp index ascends (or Dst index descends) with a corresponding increase of the fluctuation anisotropy. Thus we suggest that the fluctuation anisotropy might be a useful indicator in diagnosing the magnetic activities of magnetic clouds.

  16. Geomagnetic disturbance effects on power systems

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Space weather effects on radio propagation: study of the CEDAR, GEM and ISTP storm events

    Directory of Open Access Journals (Sweden)

    D. V. Blagoveshchensky

    2008-06-01

    Full Text Available The impact of 14 geomagnetic storms from a list of CEDAR, GEM and ISTP storms, that occurred during 1997–1999, on radio propagation conditions has been investigated. The propagation conditions were estimated through variations of the MOF and LOF (the maximum and lowest operation frequencies on three high-latitude HF radio paths in north-west Russia. Geophysical data of Dst, Bz, AE as well as some riometer data from Sodankyla observatory, Finland, were used for the analysis. It was shown that the storm impact on the ionosphere and radio propagation for each storm has an individual character. Nevertheless, there are common patterns in variation of the propagation parameters for all storms. Thus, the frequency range Δ=MOF−LOF increases several hours before a storm, then it narrows sharply during the storm, and expands again several hours after the end of the storm. This regular behaviour should be useful for the HF radio propagation predictions and frequency management at high latitudes. On the trans-auroral radio path, the time interval when the signal is lost through a storm (tdes depends on the local time. For the day-time storms an average value tdes is 6 h, but for night storms tdes is only 2 h. The ionization increase in the F2 layer before storm onset is 3.5 h during the day-time and 2.4 h at night. Mechanisms to explain the observed variations are discussed including some novel possibilities involving energy input through the cusp.

  18. Secular variation of the middle and late Miocene geomagnetic field recorded by the Columbia River Basalt Group in Oregon, Idaho and Washington, USA

    Science.gov (United States)

    Dominguez, Ada R.; Van der Voo, Rob

    2014-06-01

    This study of 118 discrete volcanic flows from the Columbia River Basalt Group is aimed to determine their distribution of geomagnetic field directions and virtual geomagnetic poles (VGPs) and to compare the inherent secular variation parameters with those from other studies. The magnetic signature of these rocks is uniformly carried by primary titanomagnetite, indicating that magnetic changes are due to variations in the magnetic field. Although most flows are flat lying, those that are tilted pass the Tauxe and Watson tilt test. Sequential flows with statistically similar site means were grouped, and directions that were considered outliers were evaluated and removed using the Vandamme cut-off method. Three normal-polarity (N-polarity) and three reversed-polarity (R-polarity) intervals are revealed by the stratigraphically ordered flows and have mean directions of N polarity (dec/inc = 6.6°/+61.2°, k = 29.3, α95 = 4.2°), and R polarity (dec/inc = 178.2°/-59.2°, k = 16, α95 = 5.5°). Regression analysis indicates that the secular variation analysis has not been affected by regional rotation, and that apparent polar wander is negligible. The VGP distribution is almost perfectly circular and supports the preference of VGP positions for the dispersion analysis. Dispersion parameters with corrections for within-site scatter (Sb) show a range of 14.3°-25.5°, including error limits, and were consistently higher for R-polarity results than for those of N polarity. Published dispersion parameters for extrusives <5 Ma show Sb values slightly lower than ours, yielding values of 16°-19°, although the difference is not statistically significant. In contrast, published dispersion parameters from high quality data from the Cretaceous Normal Superchron are lower than those for the Neogene, which suggests that the noisiness of the magnetic field correlates with the frequency of reversals. Our new results allow us to extend the Plio-Pleistocene palaeosecular variation

  19. What happens when the geomagnetic field reverses?

    CERN Document Server

    Lemaire, Joseph F

    2012-01-01

    During geomagnetic field reversals the radiation belt high-energy proton populations become depleted. Their energy spectra become softer, with the trapped particles of highest energies being lost first, and eventually recovering after a field reversal. The radiation belts rebuild in a dynamical way with the energy spectra flattening on the average during the course of many millennia, but without ever reaching complete steady state equilibrium between successive geomagnetic storm events determined by southward turnings of the IMF orientation. Considering that the entry of galactic cosmic rays and the solar energetic particles with energies above a given threshold are strongly controlled by the intensity of the northward component of the interplanetary magnetic field, we speculate that at earlier epochs when the geomagnetic dipole was reversed, the entry of these energetic particles into the geomagnetic field was facilitated when the interplanetary magnetic field was directed northward. Unlike in other compleme...

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

    Science.gov (United States)

    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.

  1. New Archaeointensity Result from Middle-Eastern China and Its Constraints on the Variation of the Geomagnetic Field during the last 6 kyr

    Science.gov (United States)

    Cai, S.; Jin, G.; Deng, C.; Tauxe, L.; Qin, H.; Pan, Y.; Zhu, R.

    2015-12-01

    Archaeomagnetic study is an effective way to understand the variation of the geomagnetic field over periods of hundreds to thousands of years. We have carried out archaeointensity studies on archaeological artifacts, including pottery fragments, bricks and baked clay, collected from several sites covering the middle to eastern part of China spanning the past ~6 kyr. We designed detailed rock magnetic and archaeointensity experiments in this study. Rock magnetic results indicate that the main magnetic carriers of these samples are stable magnetite or titanomagnetite with mainly fine particles of SD and SP. About 40% of the specimens in the paleointensity experiment pass the strict selection criteria and are considered to record robust intensity values. The virtual axial dipole moments (VADMs) of our sites range from ~2.5×1022 to ~15.8×1022 Am2. We record three low intensity values with VADMs of less than 3×1022 Am2, two of them comparable to the one reported by Cai et al. (2015) at ~3000 BCE while the other one comparable to those reported by Cai et al. (2014) at ~2200 BCE, which supply further evidence for the existence of 'DIPs' (decreases in paleoinetnsity) in China during the period of ~3000-2000 BCE. A high intensity value of ~16×1022 Am2 is recorded by our new data at ~1300 BCE, which may represent a new spike at this time period. The low and high values recorded by our new data update the six-fold variation between ~2200 BCE and ~1300 BCE discussed in Cai et al. (2014) to eight-fold, which may indicate a stronger geodynamic process during this period. Our new data are generally in good agreement with the published data in China, Japan and Korea at similar time periods, except the extreme low and high values discussed above, which will improve the Eastern Asian model greatly. The new data together with the published data suggest severe fluctuation of the geomagnetic field in Eastern Asia during the last 6 kyr. Vast quantities of reliable data are needed to

  2. The storm-time ring current: a statistical analysis at two widely separated low-latitude stations

    Directory of Open Access Journals (Sweden)

    P. Francia

    2004-11-01

    Full Text Available We conducted a statistical analysis of the geomagnetic field variations during the storm main phase at two low-latitude stations, separated by several hours in magnetic local time, in order to investigate the asymmetry and longitudinal extent of the storm-time ring current. The results show evidence for an asymmetric current which typically extends from evening to noon and, during moderate solar wind electric field conditions, up to the early morning, confirming the important role of the magnetospheric convection in the ring current energization. We also analyzed a possible relationship between the local current intensity during the storm main phase and the substorm activity observed at different time delays τ with respect to the storm onset. The results show a significant anticorrelation for τ =-1h, indicating that if the substorm activity is high just before the storm, a weaker ring current develops.

  3. K-type geomagnetic index nowcast with data quality control

    Directory of Open Access Journals (Sweden)

    René Warnant

    2011-07-01

    Full Text Available

    A nowcast system for operational estimation of a proxy K-type geomagnetic index is presented. The system is based on a fully automated computer procedure for real-time digital magnetogram data acquisition that includes screening of the dataset and removal of the outliers, estimation of the solar regular variation (SR of the geomagnetic field, calculation of the index, and issuing of an alert if storm-level activity is indicated. This is a time-controlled (rather than event-driven system that delivers the regular output of: the index value, the estimated quality flag, and eventually, an alert. The novel features provided are first, the strict control of the data input and processing, and second, the increased frequency of production of the index (every 1 h. Such quality control and increased time resolution have been found to be of crucial importance for various applications, e.g. ionospheric monitoring, that are of particular interest to us and to users of our service. The nowcast system operability, accuracy and precision have been tested with instantaneous measurements from recent years. A statistical comparison between the nowcast and the definitive index values shows that the average root-mean-square error is smaller than 1 KU. The system is now operational at the site of the Geophysical Centre of the Royal Meteorological Institute in Dourbes (50.1ºN, 4.6ºE, and it is being used for alerting users when geomagnetic storms take place.

  4. Magnetic storms and induction hazards

    Science.gov (United States)

    Love, Jeffrey J.; Rigler, E. Joshua; Pulkkinen, Antti; Balch, Christopher

    2014-01-01

    Magnetic storms are potentially hazardous to the activities and technological infrastructure of modern civilization. This reality was dramatically demonstrated during the great magnetic storm of March 1989, when surface geoelectric fields, produced by the interaction of the time-varying geomagnetic field with the Earth's electrically conducting interior, coupled onto the overlying Hydro-Québec electric power grid in Canada. Protective relays were tripped, the grid collapsed, and about 9 million people were temporarily left without electricity [Bolduc, 2002].

  5. Storm time equatorial magnetospheric ion temperature derived from TWINS ENA flux

    Science.gov (United States)

    Katus, R. M.; Keesee, A. M.; Scime, E.; Liemohn, M. W.

    2017-04-01

    The plasma sheet plays an integral role in the transport of energy from the magnetotail to the ring current. We present a comprehensive study of the equatorial magnetospheric ion temperatures derived from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) energetic neutral atom (ENA) measurements during moderate to intense (Dstpeak Los Alamos National Laboratory magnetospheric plasma analyzer. The ion temperatures are analyzed as a function of storm time, local time, and L shell. We perform a normalized superposed epoch analysis of 48 geomagnetic storms and examine the spatial and temporal evolution of the plasma as a function of storm phase. This analysis illustrates the spatial and temporal variation of the ions from the plasma sheet into the inner magnetosphere. We find that the ion temperature increases approaching the storm peak. This enhancement has the largest magnetic local time extent near 12 RE distance downtail.

  6. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites........ The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...

  7. Characterizing Extreme Ionospheric Storms

    Science.gov (United States)

    Sparks, L.; Komjathy, A.; Altshuler, E.

    2011-12-01

    Ionospheric storms consist of disturbances of the upper atmosphere that generate regions of enhanced electron density typically lasting several hours. Depending upon the storm magnitude, gradients in electron density can sometimes become large and highly localized. The existence of such localized, dense irregularities is a major source of positioning error for users of the Global Positioning System (GPS). Consequently, satellite-based augmentation systems have been implemented to improve the accuracy and to ensure the integrity of user position estimates derived from GPS measurements. Large-scale irregularities generally do not pose a serious threat to estimate integrity as they can be readily detected by such systems. Of greater concern, however, are highly localized irregularities that interfere with the propagation of a signal detected by a user measurement but are poorly sampled by the receivers in the system network. The most challenging conditions have been found to arise following disturbances of large magnitude that occur only rarely over the course of a solar cycle. These extremely disturbed conditions exhibit behavior distinct from moderately disturbed conditions and, hence, have been designated "extreme storms". In this paper we examine and compare the behavior of the extreme ionospheric storms of solar cycle 23 (or, more precisely, extreme storms occurring between January 1, 2000, and December 31, 2008), as represented in maps of vertical total electron content. To identify these storms, we present a robust means of quantifying the regional magnitude of an ionospheric storm. Ionospheric storms are observed frequently to occur in conjunction with magnetic storms, i.e., periods of geophysical activity as measured by magnetometers. While various geomagnetic indices, such as the disturbance storm time (Dst) and the planetary Kp index, have long been used to rank the magnitudes of distinct magnetic storms, no comparable, generally recognized index exists for

  8. Estimating ionospheric currents by inversion from ground-based geomagnetic data and calculating geoelectric fields for studies of geomagnetically induced currents

    Science.gov (United States)

    de Villiers, J. S.; Pirjola, R. J.; Cilliers, P. J.

    2016-09-01

    This research focuses on the inversion of geomagnetic variation field measurements to obtain the source currents in the ionosphere and magnetosphere, and to determine the geoelectric fields at the Earth's surface. During geomagnetic storms, the geoelectric fields create geomagnetically induced currents (GIC) in power networks. These GIC may disturb the operation of power systems, cause damage to power transformers, and even result in power blackouts. In this model, line currents running east-west along given latitudes are postulated to exist at a certain height above the Earth's surface. This physical arrangement results in the fields on the ground being composed of a zero magnetic east component and a nonzero electric east component. The line current parameters are estimated by inverting Fourier integrals (over wavenumber) of elementary geomagnetic fields using the Levenberg-Marquardt technique. The output parameters of the model are the ionospheric current strength and the geoelectric east component at the Earth's surface. A conductivity profile of the Earth is adapted from a shallow layered-Earth model for one observatory, together with a deep-layer model derived from satellite observations. This profile is used to obtain the ground surface impedance and therefore the reflection coefficient in the integrals. The inputs for the model are a spectrum of the geomagnetic data for 31 May 2013. The output parameters of the model are spectrums of the ionospheric current strength and of the surface geoelectric field. The inverse Fourier transforms of these spectra provide the time variations on the same day. The geoelectric field data can be used as a proxy for GIC in the prediction of GIC for power utilities. The current strength data can assist in the interpretation of upstream solar wind behaviour.

  9. Predicting the occurrence of super-storms

    Directory of Open Access Journals (Sweden)

    N. Srivastava

    2005-11-01

    Full Text Available A comparative study of five super-storms (Dst<-300 nT of the current solar cycle after the launch of SoHO, to identify solar and interplanetary variables that influence the magnitude of resulting geomagnetic storms, is described. Amongst solar variables, the initial speed of a CME is considered the most reliable predictor of the strength of the associated geomagnetic storm because fast mass ejections are responsible for building up the ram pressure at the Earth's magnetosphere. However, although most of the super-storms studied were associated with high speed CMEs, the Dst index of the resulting geomagnetic storms varied between -300 to -472 nT. The most intense storm of 20 November 2003, (Dst ~ -472 nT had its source in a comparatively smaller active region and was associated with a relatively weaker, M-class flare while all other super-storms had their origins in large active regions and were associated with strong X-class flares. However, this superstorm did not show any associated extraordinary solar and interplanetary characteristics. The study also reveals the challenge in the reliable prediction of the magnitude of a geomagnetic storm from solar and interplanetary variables.

  10. The effect of geomagnetic storms on suicide

    African Journals Online (AJOL)

    QuickSilver

    South African Psychiatry Review - August 2003. 24. The effect of ... ology, astrology and medicine, had a basic theory that an invis- ... found a high correlation between the admission rate of 3449 pa- ... Design: A retrospective analysis over a 13 year period, .... Coefficient method from the Statistix PC package was used.

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

    Science.gov (United States)

    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 lat