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Sample records for geomagnetic storm variations

  1. Semiannual variations of great geomagnetic storms: Solar sources of great storms. (Reannouncement with new availability information)

    SciTech Connect

    Cliver, E.W.; Crooker, N.U.; Cane, H.V.

    1992-01-01

    The authors report preliminary results of an investigation of the solar sources of 25 great geomagnetic storms with D sub st < or = {minus}250 nT occurring from 1957-1990. These storms exhibit a clear semiannual variation with 14 events occurring within {+-} 30 days of the equinoxes vs. 5 storms within {+-} 30 days of the solstices. This seasonal variation appears to result from a variable threshold for the size of a solar event required to produce a great geomagnetic storm, in the sense that weaker solar events, such as disappearing solar filaments, are more likely to produce great storms at the equinoxes than near the solstices. The great problem storms of the last four solar cycles, i.e., those storms lacking commensurate preceding solar activity, are all found to occur relatively near the equinoxes. Conversely, four of the five great storms that occurred near the solstices were preceded by truly outstanding solar flares. About half (11/25) of the great storms had obvious precursor geomagnetic activity, i.e., periods of approximately > 1 day with D sub st approximately < {minus}30 nT. The precursors can enable some weaker solar events to be more geoeffective than would otherwise be the case in two ways: (1) compression and amplification of pre-existing southward (precursor) fields by the transient shock, and (2) establishment of a lower D sub st baseline , making it easier for transient events to drive D sub st to values < or = {minus}250 nT.

  2. Latitudinal variation of the polar cusp during a geomagnetic storm

    SciTech Connect

    Meng, C.

    1982-01-01

    Large amplitude latitudinal variation of the polar cusp position was observed during the intense geomagnetic storm of 15--16 February 1980. The observation of the polar cusp, identified as the region of intense but extremely soft electron precipitation, was made by two nearly noon-midnight orbit DMSP satellites over both northern and southern hemispheres. The latitudinal shift of the polar cusp is observed to be related to the intensity variation of the ring current indicated by the hourly Dst values. The polar cusp region moved from its normal location at approx.76/sup 0/ gm lat down to approx.62/sup 0/ gm lat at the peak of this storm. This movement took about 5 hours and was detected over both hemispheres. A drastic variation in the width of the cusp region was also observed; it is very narrow (approx.1/sup 0/) during the equatorial shift and expands to > or approx. =5/sup 0/ during the poleward recovery. Variation of the polar cusp latitude with that of the Dst index was also seen during the period before the intense storm.

  3. [Biotropic effects of geomagnetic storms and their seasonal variations].

    PubMed

    Kuleshova, V P; Pulinets, S A; Sazanova, E A; Kharchenko, A M

    2001-01-01

    A substantial effect of geomagnetic storms on human health with a confidential probability P = 0.95 was revealed. The quantitative estimates of the biotropic effect are presented. For example, the frequency of occurrence of bursts exceeding the average number of hospitalized patients with mental and cardiovascular diseases during magnetic storms increases approximately 2 times compared with quiet periods (based on the data on 1983-84). The frequency of occurrence of myocardial infarction, angina pectoris, violation of cardial rhythm, acute violation of brain blood circulation during storms increases 2.1; 1.6; 1.6; 1.5 times, respectively compared with magnetically quiet periods (based on the data of 1992-96). A similarity of the seasonal distribution of the magnitude of the biotropic effect is revealed in the case of myocardial infarction and the number of magnetic storms: a maximum in the equinox and a minimum in summer.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Adriani, O.; Barbarino, G. C.; 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.; 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.; 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.

    2016-03-01

    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 (≳ 80MeV) 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 ˜7° 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 of geomagnetic cutoffs for protons with kinetic energies in the sub-GeV and GeV region.

  6. Extreme Geomagnetic Storms - 1868 - 2010

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  7. Hazards of geomagnetic storms

    USGS Publications Warehouse

    Herzog, D.C.

    1992-01-01

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

  8. On extreme geomagnetic storms

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  9. Ionospheric redistribution during geomagnetic storms.

    PubMed

    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 (Dst<-100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3-6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  11. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Singh, Vir; Dharwan, Maneesha

    2016-07-01

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

  13. The semiannual variation of great geomagnetic storms and the postshock Russell-Mcpherron effect preceding coronal mass ejecta

    NASA Technical Reports Server (NTRS)

    Crooker, N. U.; Cliver, E. W.; Tsurutani, B. T.

    1992-01-01

    Recent results indicate that the intense southward interplanetary magnetic fields (IMFs) responsible for great storms can reside in the postshock plasma preceding the driver gas of coronal mass ejections (CMEs) as well as in the driver gas itself. It is proposed here that strong southward fields in the postshock flow result from a major increase in the Russell-McPherron polarity effect through a systematic pattern of compression and draping within the ecliptic plane. Differential compression at the shock increases the Parker spiral angle and, consequently, the azimuthal field component that projects as a southward component onto earth's dipole axis. The resulting prediction is that southward fields in the postshock plasma maximize at the spring (fall) equinox in CMEs emerging from toward (away) sectors. This pattern produces a strong semiannual variation in postshock IMF orientation and may account at least in part for the observed semiannual variation of the occurrence of great geomagnetic storms.

  14. The Cause of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Nagatsuma, T.

    2001-12-01

    Although the cause of magnetic storms is important issue, the exact mechanism of the storm development is still controversial. Two mechanisms of storm development are considered. One is that the frequent substorm activity injects high-energy particles to the inner magnetosphere; the other is that the enhanced convection plays a role. Further, Iyermori and Rao [1996] shows that the substorm reduces the development of storms. On the contrary, magnetospheric convections and magnetic storms correspond different solar wind parameter. It is well known that the variations of the magnetospheric convection correspond to merging electric field (Em) by Kan and Lee [1979]. However, the variations of the magenetic storm correspond Ey [e.g. Burton et al., 1975]. This suggests that magnetospheric convection and magnetic storm are independent phenomena. However, we cannot discuss the independency of two phenomena since the difference between Em and Ey is small, under usual solar wind condition. We have analyzed Nov. 8, 1998 storm event, since the big difference between Em and Ey exists during 6 hours. The enhancement of Ey terminates first, and Em continues to enhance more than 6 hours after that. Although the variation of the storm estimated from SYM-H(Dst) index corresponds to Ey, that of the magnetospheric convection estimated from PC index corresponds to Em. This shows that the development of the storm terminate although the magnetospheric convection still enhances. This result suggests that the development of magnetic storms is independent from enhanced convection and the magnetic storm is directly caused by the enhancement of Ey in the solar wind.

  15. On the watch for geomagnetic storms

    USGS Publications Warehouse

    Green, Arthur W.; Brown, William M.

    1997-01-01

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

  16. Large Geomagnetic Storms: Introduction to Special Section

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2010-01-01

    Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst < or = -100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section.

  17. Geomagnetic storms: historical perspective to modern view

    NASA Astrophysics Data System (ADS)

    Lakhina, Gurbax S.; Tsurutani, Bruce T.

    2016-12-01

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

  18. Storm-time variation of the horizontal and vertical components of the geomagnetic fields and rate of induction at different latitudes

    NASA Astrophysics Data System (ADS)

    Falayi, E. O.; Oyebanjo, O. A.; Omotosho, T. V.; Okusanya, A. A.

    2016-10-01

    The paper presents the hourly mean variation of horizontal (H) and vertical (Z) components of the geomagnetic field and the rate of induction ΔH/ΔZ at different latitudes during magnetic storm of 20 March 2001 and 1 October 2001. The results of the analysis revealed that at high latitude stations greater than 60°, the reduction in ΔH component was noticed after the noon time while other stations less than 60° experienced reduction of H in the morning time during the geomagnetic storm. Large amplitude of ΔH and ΔZ were exhibited during the daytime over the equatorial zone, the amplitude decreases from mid latitudes to the dip equator during the nighttime. The daytime enhancement of ΔH at AAE, BAN and MBO suggest the presence of a strong eastward directed current which comes under the influence of electrojet. There were strong positive and negative correlations between ring current (DR) and horizontal component of the magnetic field ΔH. The effect of rate of induction is more significant at high latitudes than lower latitudes, during the geomagnetic storm. More enhancement in rate of induction occurred at nighttime than daytime. This result may be from other sources other than the ionosphere that is magnetospheric process significantly contributes toward the variation of induction.

  19. Quantifying Power Grid Risk from Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Reddy, A.; Sonwalkar, V. S.

    2015-12-01

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

  1. Research on Historical Records of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    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 < -500 nT, where Dst stands for the disturbance storm time index that measures the strength of the magnetic storm) although relatively rare, have the largest societal and technological relevance. Such storms can 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. The Causes of Geomagnetic Storms During Solar Maximum

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  3. Principles of major geomagnetic storms forecasting

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  5. The causes of geomagnetic storms during solar maximum

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1994-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. In investigating the causes of geomagnetic storms occurring during solar maximum, the following topics are discussed: solar phenomena; types of solar wind; magnetic reconnection and magnetic storms; an interplanetary example; and future space physics missions.

  6. Solar wind charge exchange during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Robertson, I. P.; Cravens, T. E.; Sibeck, D. G.; Collier, M. R.; Kuntz, K. D.

    2012-04-01

    On 2001 March 31 a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 R_E. The NASA/GSFC Community Coordinated Modeling Center (CCMC) 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 soft 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 2000 July 14 (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.

  7. NOAA Plans for Geomagnetic Storm Observations

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  9. AI techniques in geomagnetic storm forecasting

    NASA Astrophysics Data System (ADS)

    Lundstedt, Henrik

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

  10. Space Weather Monitoring for ISS Geomagnetic Storm Studies

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Parker, Linda Neergaard

    2013-01-01

    The International Space Station (ISS) space environments community utilizes near real time space weather data to support a variety of ISS engineering and science activities. The team has operated the Floating Potential Measurement Unit (FPMU) suite of plasma instruments (two Langmuir probes, a floating potential probe, and a plasma impedance probe) on ISS since 2006 to obtain in-situ measurements of plasma density and temperature along the ISS orbit and variations in ISS frame potential due to electrostatic current collection from the plasma environment (spacecraft charging) and inductive (vxB) effects from the vehicle motion across the Earth s magnetic field. An ongoing effort is to use FPMU for measuring the ionospheric response to geomagnetic storms at ISS altitudes and investigate auroral charging of the vehicle as it passes through regions of precipitating auroral electrons. This work is challenged by restrictions on FPMU operations that limit observation time to less than about a third of a year. As a result, FPMU campaigns ranging in length from a few days to a few weeks are typically scheduled weeks in advance for ISS engineering and payload science activities. In order to capture geomagnetic storm data under these terms, we monitor near real time space weather data from NASA, NOAA, and ESA sources to determine solar wind disturbance arrival times at Earth likely to be geoeffective (including coronal mass ejections and high speed streams associated with coronal holes) and activate the FPMU ahead of the storm onset. Using this technique we have successfully captured FPMU data during a number of geomagnetic storm periods including periods with ISS auroral charging. This presentation will describe the strategies and challenges in capturing FPMU data during geomagnetic storms, the near real time space weather resources utilized for monitoring the space weather environment, and provide examples of auroral charging data obtained during storm operations.

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

    NASA Astrophysics Data System (ADS)

    Stauning, Peter

    2013-06-01

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

  12. Correlative comparison of geomagnetic storms and auroral substorms using geomagnetic indeces. Master's thesis

    SciTech Connect

    Cade, W.B.

    1993-06-01

    Partial contents include the following: (1) Geomagnetic storm and substorm processes; (2) Magnetospheric structure; (3) Substorm processes; (4) Data description; (5) Geomagnetic indices; and (6) Data period and data sets.

  13. Halo Coronal Mass Ejections and Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2009-01-01

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

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

    USGS Publications Warehouse

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Tiwari, Bhupendra Kumar

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

  17. Solar Wind Charge Exchange During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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. Plasmasphere Refilling After Geomagnetic Storms Observed by EMMA Magnetometer Network

    NASA Astrophysics Data System (ADS)

    Del Corpo, A.; Vellante, M.; Heilig, B.; Lichtenberger, J.; Reda, J.; Pietropaolo, E.; Chi, P. J.

    2015-12-01

    We present the results of a study of plasmasphere dynamics during a few geomagnetic storms through examination of radial profiles of the equatorial plasma mass density. The plasma mass density is derived from field line resonance (FLR) frequencies observations across EMMA, a meridional network of 25 magnetometer stations extending from Central Italy to North Finland (1.5 < L < 6.5). The study focuses on plasmaspheric refilling following depletion due to geomagnetic activity. From the time variation of the equatorial plasma mass density we derived daytime refilling rates and the corresponding upward plasma fluxes from the ionosphere for different L-values. Daily averaged refilling rates occurring during the recovery phase have been also investigated.

  20. Transient cosmic ray increase associated with a geomagnetic storm

    NASA Technical Reports Server (NTRS)

    Kudo, S.; Wada, M.; Tanskanen, P.; Kodama, M.

    1985-01-01

    On the basis of worldwide network data of cosmic ray nucleonic components, the transient cosmic ray increase due to the depression of cosmic ray cutoff rigidity during a severe geomagnetic storm was investigated in terms of the longitudinal dependence. Multiple correlation analysis among isotropic and diurnal terms of cosmic ray intensity variations and Dst term of the geomagnetic field is applied to each of various station's data. It is shown that the amplitude of the transient cosmic ray increase associated with Dst depends on the local time of the station, and that its maximum phase is found in the evening sector. This fact is consistent with the theoretical estimation based on the azimuthally asymmetric ring current model for the magnetic DS field.

  1. Statistical Relationship between Sawtooth Oscillations and Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Hun; Lee, Dae-Young; Choi, Cheong-Rim; Her, Young-Tae; Han, Jin-Wook; Hong, Sun-Hak

    2008-06-01

    We have investigated a statistical relationship between sawtooth oscillations and geomagnetic storms during 2000-2004. First of all we selected a total of 154 geomagnetic storms based on the Dst index, and distinguished between different drivers such as Coronal Mass Ejection (CME) and Co-rotating Interaction Region (CIR). Also, we identified a total of 48 sawtooth oscillation events based on geosynchronous energetic particle data for the same 2000-2004 period. We found that out of the 154 storms identified, 47 storms indicated the presence of sawtooth oscillations. Also, all but one sawtooth event identified occurred during a geomagnetic storm interval. It was also found that sawtooth oscillation events occur more frequently for storms driven by CME (˜62%) than for storms driven by CIR (˜30%). In addition, sawtooth oscillations occurred mainly (˜82%) in the main phase of storms for CME-driven storms while they occurred mostly (˜78%) during the storm recovery phase for CIR-driven storms. Next we have examined the average characteristics of the Bz component of IMF, and solar wind speed, which were the main components for driving geomagnetic storm. We found that for most of the sawtooth events, the IMF Bz corresponds to --15 to 0 nT and the solar wind speed was in the range of 400˜700 km/s. We found that there was a weak tendency that the number of teeth for a given sawtooth event interval was proportional to the southward IMF Bz magnitude.

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

    DOE PAGES

    Anderson, B. R.; Millan, R. M.; Reeves, G. D.; ...

    2015-12-02

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

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

    SciTech Connect

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

    2015-12-02

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

  4. Major Geomagnetic Storms in Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Zheng, Y.

    2013-12-01

    Solar Cycle 24 has produced 11 major geomagnetic storms (where Dstmin < -100 nT) with three in 2011, six in 2012 and two in 2013 (as of 7 August 2013). Detailed analysis of each event will be given in terms of its solar driver(s): CME, coronal hole high speed solar wind stream (HSS), multiple CMEs or interactions between CME and HSS. While some of these storms are associated with a fast and wide CME, the few cases involving slow or common CMEs and interactions with HSS are particularly interesting. These events pose great challenges for accurate space weather forecasting, since operationally the slower or average CMEs tend to receive less attention and are sometimes overlooked altogether. The characteristics of such challenging, not-so-fast yet geoeffective CME events (such as their coronal signatures and interactions with surrounding solar wind structure(s), etc) will be examined in detail, with the goal of extracting common and telltale features, if any, of these CMEs that distinguish them from CMEs in a similar category.

  5. Polar and equatorial ionosphere interaction during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Biktash, L.

    The solar wind-magnetosphere-ionosphere coupling as applied to the polar and equatorial ionosphere dynamics is examined. To do this simultaneous observations of the IMF, ground-based measurements of the ionospheric parameters and geomagnetic field variations from the high latitudes to the equator are used during magnetic storms. It is shown that the auroral electric fields during magnetically disturbed conditions by the magnetospheric current systems can play a dominant role in the equatorial ionosphere processes. During magnetic storms the equatorial ionosphere parameters h'F, foF2 and etc. widely deviated from quiet day conditions and different kinds of ionospheric irregularities are formed. The equatorial ionospheric irregularities manifest as spread F in ionograms, reversals of drift velocities, scintillation of radio transmissions through the ionosphere, etc. These phenomena can interpret as the result of direct penetration of electric fields from the high latitude field-aligned currents (FAC) to the equatorial ionosphere. Model of direct penetration of FAC electric field of Polar Regions 1 and Region 2, which are controlled by the solar wind, to the equatorial ionosphere is presented. From this model the solar wind electric field through the FAC is likely to the factor wich generate or inhibit the equatorward penetration of the high latitude electric field. We demonstrate that the model is suitable to explain h'F, foF2 variations and scintillation activity during geomagnetic storms. Taking into account of the equatorial and auroral electric fields coupling, relationship, between these regions can be useful to study difficult auroral conditions during magnetic storms.

  6. Comment on 'The semiannual variation of great geomagnetic storms and the postshock Russell-McPherron effect preceding coronal mass ejecta' by N. U. Crooker, E. W. Cliver and B. T. Tsurutani

    NASA Technical Reports Server (NTRS)

    Gonzalez, W. D.; Clua De Gonzalez, A. L.; Tsurutani, B. T.

    1993-01-01

    It is proposed by Crooker et al. (1992) that for a subgroup of great geomagnetic storms, for which the associated strong southward IMF (B(S)) fields reside in the postshock plasma, preceding the driver gas of coronal mass ejections, such strong B(S) fields result from a 'major increase in the Russell-McPherron polarity effect, through a systematic pattern of compression and draping' of the Archimedean field in the x-y plane. The critics test the scenario proposed by Crooker et al., namely, that the Russell-McPherron polarity effect is a major contribution to the semiannual variable of intense geomagnetic storms. It is found by the critics that in the cases studied there is little difference between the B(S) values as measured in geocentric solar ecliptic and geocentric solar magnetospheric coordinates, and it is concluded that the Russell-McPherron mechanism cannot explain by itself the seasonal dependence of intense storms, for which the variation is the largest. Crooker et al. present arguments to show that the combined preshock and postshock Russell-McPherron effect remains the sole cause of the semiannual variation of great storm occurrence.

  7. Response of the thermosphere and ionosphere to geomagnetic storms

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Technical Reports Server (NTRS)

    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.

  9. Morphological Investigation of Disturbed Ionosphere during Intense Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Malvi, Bhupendra; Srivastav, Prateek S.; Mansoori, Azad A.; Atulkar, Roshni; Bhardwaj, Shivangi; Purohit, P. K.

    2016-10-01

    Geomagnetic Storms are the disturbed magnetic conditions, influenced and induced by Interplanetary Magnetic Field and the Charged Particle's motion around the Earth, respectively, in Geospace. As the ionosphere is woven by the earth's magnetic field it responds to the change in that. During the geomagnetic storms the filled-in plasma between the magnetic field lines, geomagnetic flux tubes, redistributes itself in effect of the magnetic field forcing. In the present study we have done the investigation of the morphology of the ionosphere over the mid and high latitude regions during intense Geomagnetic Storms. We got fairly convincing results; in three cases decrease of the critical frequency of F2 layer (foF2) and in one case enhancement of the critical frequency of F2 layer (foF2) at mid and high latitudes.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    SciTech Connect

    Brinkman, D.G.

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  15. Longitudinal Hemispheric Differences During Geomagnetic Storm Times Examined with GITM

    NASA Astrophysics Data System (ADS)

    Greer, K.; Immel, T. J.; Ridley, A. J.

    2015-12-01

    Work by Immel and Mannucci [2013] has indicated that geomagnetic storms cause larger effects on the ionospheric TEC (Total Electron Count) in the American sector than anywhere else on the planet, suggesting that there is a longitude dependent (UT) effect which is important for correctly understanding the impact, structure and timing of geomagnetic storms. Using Global Ionosphere-Thermosphere Model (GITM) [Ridley et al., 2006] coupled with realistic transport, we examine the underlying mechanisms of the longitude-dependent storm enhancements. We accomplish this by using a case study storm observed on 5 August 2011 and then conducting model experiments with GITM by shifting the storm onset time over the course of 24 hours. TEC measurements, the Dst index, and IMF are used in conjunction with model output.

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  17. Installation of Induced Current Measurement Systems in Substations and Analysis of GIC Data during Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Choi, Kyu-Cheol; Park, Mi-Young; Ryu, Youngsoo; Hong, Youngsu; Yi, Jong-Hyuk; Park, Sung-Won; Kim, Jae-Hun

    2015-12-01

    Coronal Mass Ejections (CME), which originate from active regions of the Sun's surface, e.g., sunspots, result in geomagnetic storms on Earth. The variation of the Earth's geomagnetic field during such storms induces surface currents that could cause breakdowns in electricity power grids. Hence, it is essential to both monitor Geomagnetically Induced Currents (GICs) in real time and analyze previous GIC data. In 2012, in order to monitor the variation of GICs, the Korean Space Weather Center (KSWC) installed an induced current measurement system at SINGAPYEONG Substation, which is equipped with 765 kV extra-high-voltage transformers. Furthermore, in 2014, two induced current measurement systems were installed on the 345 kV high-voltage transformers at the MIGEUM and SINPOCHEON substations. This paper reports the installation process of the induced current measurement systems at these three substations. Furthermore, it presents the results of both an analysis performed using GIC data measured at the SINGAPYEONG Substation during periods of geomagnetic storms from July 2013 through April 2015 and the comparison between the obtained GIC data and magnetic field variation (dH/dt) data measured at the Icheon geomagnetic observatory.

  18. The causes of recurrent geomagnetic storms

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  19. Planetary distribution of geomagnetic pulsations during a geomagnetic storm at solar minimum

    NASA Astrophysics Data System (ADS)

    Kleimenova, N. G.; Kozyreva, O. V.

    2014-01-01

    We investigate the features of the planetary distribution of wave phenomena (geomagnetic pulsations) in the Earth's magnetic shell (the magnetosphere) during a strong geomagnetic storm on December 14-15, 2006, which is untypical of the minimum phase of solar activity. The storm was caused by the approach of the interplanetary magnetic cloud towards the Earth's magnetosphere. The study is based on the analysis of 1-min data of global digital geomagnetic observations at a few latitudinal profiles of the global network of ground-based magnetic stations. The analysis is focused on the Pc5 geomagnetic pulsations, whose frequencies fall in the band of 1.5-7 mHz ( T ˜ 2-10 min), on the fluctuations in the interplanetary magnetic field (IMF) and in the solar wind density in this frequency band. It is shown that during the initial phase of the storm with positive IMF Bz, most intense geomagnetic pulsations were recorded in the dayside polar regions. It was supposed that these pulsations could probably be caused by the injection of the fluctuating streams of solar wind into the Earth's ionosphere in the dayside polar cusp region. The fluctuations arising in the ionospheric electric currents due to this process are recorded as the geomagnetic pulsations by the ground-based magnetometers. Under negative IMF Bz, substorms develop in the nightside magnetosphere, and the enhancement of geomagnetic pulsations was observed in this latitudinal region on the Earth's surface. The generation of these pulsations is probably caused by the fluctuations in the field-aligned magnetospheric electric currents flowing along the geomagnetic field lines from the substorm source region. These geomagnetic pulsations are not related to the fluctuations in the interplanetary medium. During the main phase of the magnetic storm, when fluctuations in the interplanetary medium are almost absent, the most intense geomagnetic pulsations were observed in the dawn sector in the region corresponding to the

  20. New insights on geomagnetic storms from observations and modeling

    SciTech Connect

    Jordanova, Vania K

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.; Babayev, E. S.; Mustafa, F. R.; Stoilova, I.; Taseva, T.; Georgieva, K.

    2009-12-01

    Results of collaborative studies on revealing a possible relationship between solar activity (SA) and geomagnetic activity (GMA) and pre-hospital acute myocardial infarction (AMI) morbidity are presented. Studies were based on medical data from Bulgaria and Azerbaijan. Bulgarian data, covering the period from 01.12.1995 to 31.12.2004, concerned daily distribution of number of patients with AMI diagnose (in total 1192 cases) from Sofia Region on the day of admission at the hospital. Azerbaijani data contained 4479 pre-hospital AMI incidence cases for the period 01.01.2003-31.12.2005 and were collected from 21 emergency and first medical aid stations in Grand Baku Area (including Absheron Economical Region with several millions of inhabitants). Data were "cleaned" as much as possible from social and other factors and were subjected to medical and mathematical/statistical analysis. Medical analysis showed reliability of the used data. Method of ANalysis Of VAriance (ANOVA) was applied to check the significance of GMA intensity effect and the type of geomagnetic storms - those caused by magnetic clouds (MC) and by high speed solar wind streams (HSSWS) - on AMI incidences. Relevant correlation coefficients were calculated. Results were outlined for both considered data. Results obtained for the Sofia data showed statistically significant positive correlation between considered GMA indices and AMI occurrence. ANOVA revealed that AMI incidence number was significantly increased from the day before till the day after geomagnetic storms with different intensities. Geomagnetic storms caused by MC were related to significant increase of AMI number in comparison with the storms caused by HSSWS. There was a trend for such different effects even on -1st and +1st day for the period 1995-2004. Results obtained for the Baku data revealed trends similar to those obtained for Sofia data. AMI morbidity increment was observed on the days with higher GMA intensity and after these days

  3. Modeling Longitudinal Hemispheric Differences during Geomagnetic Storm Times

    NASA Astrophysics Data System (ADS)

    Greer, K.; Immel, T. J.; Ridley, A. J.

    2014-12-01

    Work by Immel and Mannucci [2013] has indicated that geomagnetic storms causes a larger effect on the ionospheric TEC (Total Electron Count) in the American sector than anywhere else on the planet, suggesting that there is a longitude dependent (UT) effect which is important for correctly understanding the impact, structure and timing of geomagnetic storms. Here we examine the extent to which numerical models appropriately reproduce the observed results. Using Global Ionosphere-Thermosphere Model (GITM) [Ridley et al., 2006] coupled with realistic transport to examine the underlying mechanisms of the longitude-dependent storm enhancements and whether these mid-latitude enhancements are connected to high-latitude changes. TEC measurements, the Dst index, and are used in conjunction with model output.

  4. A case study of the thermospheric neutral wind response to geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Jiang, Guoying; Zhang, Shunrong; Wang, Wenbin; Yuan, Wei; Wu, Qian; Xu, Jiyao

    A minor geomagnetic storm (Kp=5) occurred on March 27-28, 2012. The response of the thermospheric neutral wind at ~ 250 km to this storm was investigated by the 630.0 nm nightglow measurements of Fabry-Perot interferometers (FPIs) over Xinglong (geographic location: 40.2N, 117.4E; geomagnetic location: 29.8N, 193.2E) and Millstone Hill (geographic location: 42.6N, 71.5W; geomagnetic location: 53.1N, 65.1W). Our results show that the minor storm on March 27-28, 2012 obviously effected on the thermospheric neutral winds over Xinglong and Millstone Hill, especially Millstone Hill had larger response because of its higher geomagnetic latitude. Another interesting result is that a small variation in geomagnetic activity (Kp=2.7) could enough introduce a clear disturbance in the nighttime thermospheric neutral wind over Millstone hill. NCAR-TIME-GCM (National Center for Atmospheric Research-Thermosphere Ionosphere Mesosphere Electrodynamics-General Circulation Model) was employed to study the evolution and mechanism of the thermospheric neutral wind response.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Gopinath, Sumesh; Prince, P. R.

    2016-01-01

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

  7. Modeling the ionospheric UT effect during the August 2013 geomagnetic storm with a nonhydrostatic general circulation model

    NASA Astrophysics Data System (ADS)

    Yigit, E.; Immel, T. J.; Ridley, A. J.; Liemohn, M. W.

    2013-12-01

    Using the three-dimensional nonhydrostatic Global Ionosphere Thermosphere Model (GITM), we investigate the response of the thermosphere-ionosphere (TI) system to the August 2013 major geomagnetic storm. The model is run with observed realistic IMF, auroral and solar input and the results are compared with a simulation conducted under constant quiescent solar and geomagnetic conditions. There is a substantial amount of hemispheric asymmetry in the response of the TI system to the storm. Key momentum and energy deposition processes are diagnozed to identify mechanisms influencing the latitutidinal variations. With additional systematic simulations, we determine the dependence of upper atmosphere response on the onset time of the storm.

  8. Statistical analysis of geomagnetic storm driver and intensity

    NASA Astrophysics Data System (ADS)

    Katus, R. M.; Liemohn, M. W.

    2013-05-01

    Geomagnetic storms are investigated statistically with respect to the solar wind driver and the intensity of the events. The Hot Electron and Ion Drift Integrator (HEIDI) model was used to simulate all of the intense storms (minimum Dst < - 100 nT) from solar cycle 23 (1996-2005). Four different configurations of HEIDI were used to investigate the outer boundary condition and electric field description. The storms are then classified as being a coronal mass ejection (CME) or corotating interaction region (CIR) driven event and binned based on the magnitude of the minimum Dst. The simulation results as well as solar wind and geomagnetic data sets are then analyzed along a normalized epoch timeline. The average behavior of each storm type and the corresponding HEIDI configurations are then presented and discussed. It is found that while the self-consistent electric field better reproduces stronger CME driven storms, the Volland-Stern electric field does well reproducing the results for CIR driven events.

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

    NASA Astrophysics Data System (ADS)

    Marlia, Dessi; Wu, Falin

    2016-07-01

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

  10. Geomagnetically induced currents around the world during the 17 March 2015 storm

    NASA Astrophysics Data System (ADS)

    Carter, B. A.; Yizengaw, E.; Pradipta, R.; Weygand, J. M.; Piersanti, M.; Pulkkinen, A.; Moldwin, M. B.; Norman, R.; Zhang, K.

    2016-10-01

    Geomagnetically induced currents (GICs) represent a significant space weather issue for power grid and pipeline infrastructure, particularly during severe geomagnetic storms. In this study, magnetometer data collected from around the world are analyzed to investigate the GICs caused by the 2015 St. Patrick's Day storm. While significant GIC activity in the high-latitude regions due to storm time substorm activity is shown for this event, enhanced GIC activity was also measured at two equatorial stations in the American and Southeast Asian sectors. This equatorial GIC activity is closely examined, and it is shown that it is present both during the arrival of the interplanetary shock at the storm sudden commencement (SSC) in Southeast Asia and during the main phase of the storm ˜10 h later in South America. The SSC caused magnetic field variations at the equator in Southeast Asia that were twice the magnitude of those observed only a few degrees to the north, strongly indicating that the equatorial electrojet (EEJ) played a significant role. The large equatorial magnetic field variations measured in South America are also examined, and the coincident solar wind data are used to investigate the causes of the sudden changes in the EEJ ˜10 h into the storm. From this analysis it is concluded that sudden magnetopause current increases due to increases in the solar wind dynamic pressure, and the sudden changes in the resultant magnetospheric and ionospheric current systems, are the primary drivers of equatorial GICs.

  11. Secular trends in storm-level geomagnetic activity

    USGS Publications Warehouse

    Love, J.J.

    2011-01-01

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

  12. Solar Energetic Particle Trapping During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Hudson, M.; Kress, B.; Blake, J. B.; Mazur, J.

    2007-12-01

    The prompt trapping of Solar Energetic Particles (SEPs) in the inner magnetosphere inside of L = 4 has been reported, including protons and heavier ions, in association with high speed interplanetary shocks and Storm Sudden Commencements (SSCs). These observations include the Bastille Day 2000 CME-driven storm as well as two in November 2001, which produced a long-lived new proton belt, as well as trapping of heavy ions up to Fe in all three cases. A survey of such events around the most recent solar maximum, including high altitude measurements from Polar, HEO and ICO satellites along with low altitude measurements from SAMPEX, indicates similarities to the well-studied March 24, 1991 SSC event. In this event, electrons and protons in drift resonance with a magnetosonic impulse were transported radially inward, requiring a source population which is multi-MeV at geosynchronous. A requirement for such shock-induced acceleration is a high-speed CME- shock at 1 AU, which launches a perturbation with comparable velocity inside the magnetosphere. Secondly, there must be a source population which is drift-resonant with the impulse. The CME-shock itself is a source of solar energetic particles, both protons and heavy ions, with higher fluxes and harder spectra associated with faster moving CMEs. A 3D Lorentz integration of SEP trajectories in electric and magnetic fields taken from the Lyon-Fedder-Mobarry (LFM) global MHD model, using solar wind input parameters from spacecraft measurements upstream from the bow shock, has been carried out for two November, 2001 SEP trapping events, and a CME-shock associated with the Halloween 2003 storm period, 29 October, which transported outer zone electrons and trapped solar energetic electrons into around L = 2.5, with little effect on SEPs. These results indicate that an enhancement in solar wind dynamic pressure for these events plays a role in the observed injection of ions (and electrons) to low L-values, as does the extent of

  13. The neutral thermosphere at Arecibo during geomagnetic storms

    SciTech Connect

    Burnside, R.G.; Tepley, C.A.; Sulzer, M.P. ); Fuller-Rowell, T.J. ); Torr, D.G. ); Roble, R.G. )

    1991-02-01

    Over the past five years, simultaneous incoherent scatter and optical observations have been obtained at Arecibo, Puerto Rico, during two major geomagnetic storms. The first storm the authors examine occurred during the World Day campaign of 12-16 January 1988, where on 14 January 1988, Kp values greater than 7 were recorded. An ion-energy balance calculation shows that atomic oxygen densities at a fixed height on 14 January 1988 were about twice as large as they were on the quiet days in this period. Simultaneous radar and Fabry-Perot interferometer observations were used to infer nightime O densities on 14-15 January 1988 that were about twice as large as on adjacent quiet nights. On this night, unusually high westward ion velocities were observed at Arecibo. The Fabry-Perot measurements show that the normal eastward flow of the neutral wind was reversed on this night. The second storm they examine occured on the night of 13-14 July 1985, when Kp values reached only 4+, but the ionosphere and thermosphere responded in a similar manner as they did in January 1988. On the nights of both 13-14 July 1985 and 14-15 January 1988, the electron densities observed at Arecibo were significantly higher than they were on nearby geomagnetically quiet nights. These results indicate that major storm effects in thermospheric winds and composition propagate to low latitudes and have a pronounced effect on the ionospheric structure over Arecibo.

  14. Comparison of Dst Forecast Models for Intense Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Disturbance dynamo electric fields in response to geomagnetic storms occurring at different universal times

    NASA Astrophysics Data System (ADS)

    Huang, C.

    2013-12-01

    Perturbed electric fields in the earth's ionosphere, resulting from the penetration electric fields from high latitudes and/or from the dynamo mechanism driven by the neutral disturbances, occurr in the storm periods. In general, the identification of the penetration electric fields is easier than that of the dynamo electric fields. At times, the latter becomes unperceivable or difficult to identify. This is an interesting problem which motivates a model study to investigate the possible reasons. Model runs made with the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (NCAR/TIEGCM) will be presented. Theoretical studies of ionospheric responses to geomagnetic storms with model simulations indicate that the intensities of disturbance dynamo electric fields are highly dependent on various parameters such as solar activities, seasonal effects and universal times, etc. When geomagnetic storms commence at 01~07 UT in summer solstices with low solar fluxes, the disturbance dynamo electric fields become very small. As compared with the general daily variations, they seem to be unperceivable. This phenomenon can be explained by the model results which show that the positive charge accumulation at low latitudes will be weakened when the equatward neutral disturbances penetrate into the opposite hemisphere in the storm time. For other cases, the magnitudes of the dynamo electric fields are relatively larger under the same geomagnetic activity.

  17. On the scaling features of high-latitude geomagnetic field fluctuations during a large geomagnetic storm

    NASA Astrophysics Data System (ADS)

    De Michelis, Paola; Federica Marcucci, Maria; Consolini, Giuseppe

    2015-04-01

    Recently we have investigated the spatial distribution of the scaling features of short-time scale magnetic field fluctuations using measurements from several ground-based geomagnetic observatories distributed in the northern hemisphere. We have found that the scaling features of fluctuations of the horizontal magnetic field component at time scales below 100 minutes are correlated with the geomagnetic activity level and with changes in the currents flowing in the ionosphere. Here, we present a detailed analysis of the dynamical changes of the magnetic field scaling features as a function of the geomagnetic activity level during the well-known large geomagnetic storm occurred on July, 15, 2000 (the Bastille event). The observed dynamical changes are discussed in relationship with the changes of the overall ionospheric polar convection and potential structure as reconstructed using SuperDARN data. This work is supported by the Italian National Program for Antarctic Research (PNRA) - Research Project 2013/AC3.08 and by the European Community's Seventh Framework Programme ([FP7/2007-2013]) under Grant no. 313038/STORM and

  18. The flywheel effect: Ionospheric currents after a geomagnetic storm

    SciTech Connect

    Deng, W.; Killeen, T.L.; Burns, A.G. ); Roble, R.G. )

    1991-10-01

    In the period following a geomagnetic storm the high-latitude, magnetospheric-driven convection pattern is normally weak. However, the neutral circulation, set up by ion-neutral momentum coupling during the main phase of the storm, may continue for several hours after the storm has ended. This persistent neutral circulation has the potential to drive Hall currents for some hours. In this paper the authors investigate these flywheel' currents by simulating a storm which occurred on the 23rd of November 1982 using the National Center for Atmospheric Research Thermosphere Ionosphere General Circulation Model (NCAR-TIGCM). The resulting high-latitude, height-integrated Hall currents are dominated by the neutral-wind-driven component for several hours after the end of main phase of the storm. The direction of these currents is reversed from normal. Analysis of the neutral and ion components of this current system indicates that the neutral component may drive as much as 80% of the high-latitude current system immediately after the storm has ended, and may continue to dominate this system for 4 to 5 hours.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

    Uwamahoro, Jean Claude; Habarulema, John Bosco

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Merline Matamba, Tshimangadzo; Bosco Habarulema, John

    2016-07-01

    The analyses of ionospheric responses due to great geomagnetic storms i.e. Dst index < 350 nT that occurred during solar cycle 23 are presented. The GPS Total Electron Content (TEC) and ionosonde data over Southern and Northern Hemisphere mid-latitudes were used to study the ionospheric responses. A geomagnetic latitude region of ±30° to ±46° within a longitude sector of 15° to 40° was considered. Using a criteria of Dst < -350 nT, there were only four great storm periods (29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004) in solar cycle 23. Analysis has shown that ionospheric dynamics during these disturbed conditions could be due to a number of dynamic and electrodynamics processes in both Hemispheres. In some instances the ionosphere responds differently to the same storm condition in both Hemispheres. Physical mechanisms related to (but not limited to) composition changes and electric fields will be discussed.

  3. Multi-station observation of ionospheric irregularities over South Africa during strong geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Amabayo, Emirant Bertillas; Cilliers Pierre, J.

    2013-03-01

    This paper presents results pertaining to the response of the mid-latitude ionosphere to strong geomagnetic storms that occurred from 31 March to 02 April 2001 and 07-09 September 2002. The results are based on (i) Global Positioning Systems (GPSs) derived total electron content (TEC) variations accompanying the storm, (ii) ionosonde measurements of the ionospheric electrodynamic response towards the storms and (iii) effect of storm induced travelling ionospheric disturbances (TIDs) on GPS derived TEC. Ionospheric data comprising of ionospheric TEC obtained from GPS measurements, ionograms, solar wind data obtained from Advanced Composition Explorer (ACE) and magnetic data from ground based magnetometers were used in this study. Storm induced features in vertical TEC (VTEC) have been obtained and compared with the mean VTEC of quiet days. The response of the mid-latitude ionosphere during the two storm periods examined may be characterised in terms of increased or decreased level of VTEC, wave-like structures in VTEC perturbation and sudden enhancement in hmF2 and h‧F. The study reveals both positive and negative ionospheric storm effects on the ionosphere over South Africa during the two strong storm conditions. These ionospheric features have been mainly attributed to the travelling ionospheric disturbances (TIDs) as the driving mechanism for the irregularities causing the perturbations observed. TEC perturbations due to the irregularities encountered by the satellites were observed on satellites with pseudo random numbers (PRNs) 15, 17, 18 and 23 between 17:00 and 23:00 UT on 07 September 2002.

  4. The Dependence of the Geoeffectiveness of Interplanetary Flux Rope on Its Orientation, with Possible Application to Geomagnetic Storm Prediction

    NASA Astrophysics Data System (ADS)

    Wang, Yuming; Ye, Pinzhong; Wang, S.

    2007-02-01

    Interplanetary magnetic clouds (MCs) are one of the main sources of large non-recurrent geomagnetic storms. With the aid of a force-free flux rope model, the dependence of the intensity of geomagnetic activity (indicated by Dst index) on the axial orientation (denoted by θ and φ in GSE coordinates) of the magnetic cloud is analyzed theoretically. The distribution of the Dst values in the ( θ, φ) plane is calculated by changing the axial orientation for various cases. It is concluded that (i) geomagnetic storms tend to occur in the region of θ<0°, especially in the region of θ≲-45°, where larger geomagnetic activity could be created; (ii) the intensity of geomagnetic activity varies more strongly with θ than with φ; (iii) when the parameters B 0 (the magnetic field strength at the flux rope axis), R 0 (the radius of the flux rope), or V (the bulk speed) increase, or | D| (the shortest distance between the flux rope axis and the x-axis in GSE coordinates) decreases, a flux rope not only can increase the intensity of geomagnetic activity, but also is more likely to create a storm, however the variation of n (the density) only has a little effect on the intensity; (iv) the most efficient orientation (MEO) in which a flux rope can cause the largest geomagnetic activity appears at φ˜0° or ˜ 180°, and some value of θ which depends mainly on D; (v) the minimum Dst value that could be caused by a flux rope is the most sensitive to changes in B 0 and V of the flux rope, and for a stronger and/or faster MC, a wider range of orientations will be geoeffective. Further, through analyzing 20 MC-caused moderate to large geomagnetic storms during 1998 2003, a long-term prediction of MC-caused geomagnetic storms on the basis of the flux rope model is proposed and assessed. The comparison between the theoretical results and the observations shows that there is a close linear correlation between the estimated and observed minimum Dst values. This suggests that using

  5. Energetic particle precipitation in the Brazilian geomagnetic anomaly during the "Bastille Day storm" of July 2000

    NASA Astrophysics Data System (ADS)

    Nishino, M.; Makita, K.; Yumoto, K.; Miyoshi, Y.; Schuch, N. J.; Abdu, M. A.

    2006-05-01

    Ionospheric absorption associated with a great geomagnetic storm on July 15-16, 2000 (the "Bastille Day storm") was observed in the Brazilian geomagnetic anomaly using a two-dimensional 4×4 imaging riometer (IRIS). In the afternoon of July 15, weak absorption (~0.2 dB) was observed during the initial phase of the storm; large spatial-scale absorption exceeded the IRIS field of view (330×330 km). During the sharp magnetic decrease in the main phase of the storm, absorption was intensified (<0.5 dB) in the evening, showing a sheet structure with ~150 km latitudinal width and >330 km longitudinal elongation. Subsequently, absorption was intensified (~1 dB), having a small spatial-scale (~150 km) in the background sheet structure and a pronounced westward drift (~570 m s-1). In association with large magnetic fluctuations in the Bz component of the interplanetary magnetic field (IMF), the ground magnetic variation in the night sector showed large positive swings during the initial to main phases of the storm. With the subsequent southward turning of the IMF Bz, the ground magnetic variation in the evening sector showed rapid storm development. Particle fluxes measured by a geosynchronous satellite (L = ~6.6) demonstrated large enhancements of low-energy protons (50-400 keV) and probably electrons (50-225 keV) during the storm's initial phase. Particle fluxes from the low-altitude NOAA satellite (~870 km) indicated the invasion of low-energy particles into the region of L < 2 during the main phase of the storm. These results indicate that low-energy particles injected into the outer radiation belt in association with frequent and strong substorm occurrences, were transported into the inner radiation belt through direct convective access by the storm-induced electric fields during the storm's development. These particles then precipitated into the ionosphere over the Brazilian geomagnetic anomaly. Notably, the most intense absorption could be dominantly caused by

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

    NASA Astrophysics Data System (ADS)

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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. Study of Ring Current Dynamics During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Jordanova, Vania K.

    2000-01-01

    This research program considered modeling the dynamical evolution of the ring current during several geomagnetic storms. The first year (6/01/1997-5/31/1998) of this successful collaborative research between the University of New Hampshire (UNH) and the University of California Los Angeles (UCLA) was supported by NASA grant NAG5-4680. The second and third years (6/01/1998-5/31/2000) were funded at UNH under NASA grant NAG5-7368. Research work at UNH concentrated on further development of a kinetic model to treat all of the important physical processes that affect the ring current ion population during storm conditions. This model was applied to simulate ring current development during several International Solar-Terrestrial Physics (ISTP) events, and the results were directly compared to satellite observations. A brief description of our major accomplishments and a list of the publications and presentations resulting from this effort are given.

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

    NASA Astrophysics Data System (ADS)

    Al-Ubaidi, Najat

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  12. Problems with Modeling Plasmasphere Refilling After Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Schunk, R. W.

    2015-12-01

    During geomagnetic storms, the plasma in the outer plasmasphere is depleted as the plasma drifts away from the Earth across magnetic field (B) lines due to storm-time electric fields. After the storm, the plasmasphere refills due to an upward flow of plasma from the ionosphere that is initially supersonic (H+). The current numerical models of plasmasphere refilling are typically based on a numerical solution of the ion (H+, O+, He+) and electron continuity, momentum, and energy equations. The equations are solved along closed magnetic field lines that connect conjugate ionospheres, with allowance for cross-B plasma drift during storms. Both diffusion and hydrodynamic approximations have been adopted. The diffusion approximation neglects the nonlinear initial term in the momentum equations, so this approximation is not rigorously valid for early refilling times (~ day). At high altitudes, the plasma becomes collisionless and there are different temperatures parallel and perpendicular to B (not included in current models). Also, single-stream and multi-stream (separate ion streams from the conjugate ionospheres) formulations have been adopted, and the refilling features are different. These and other problems with the current plasmasphere refilling models will be discussed.

  13. Evolution of the ring current during two geomagnetic storms

    SciTech Connect

    Lui, A.T.Y.; McEntire, R.W.; Krimigis, S.M.

    1987-07-01

    The progressive developments in the radial profiles of the particle pressure, plasma beta, and electric currents of the storm time ring current are investigated with data from the medium energy particle analyzer on the AMPTE Charged Particle Explorer spacecraft. Measurements of ions from 25 keV to 1 MeV, which carry 70--85% of the energy density of the entire ring current population, are used in this work. Two geomagnetic storms in September of 1984 are selected and four traversals of the equatorial ring current region during the course of each storm are studied. It is shown that enhancements in the particle pressure occur initially in the outer region and reach the inner region in the late phase of the storm. Structures suggestive of multiple particle injections are seen in the pressure profile. The leading and trailing edges of the particle injection structures are associated, respectively, with the depressions and enhancements of the westward current densities of the ring current. Plasma beta occasionally increases to values of the order of 1 in some regions of the ring current from prestorm values of the order of 0.1 or less. It is also found that the location of the maximum ring current particle pressure can be several earth radii from where the most intense westward ring current flows. This is a consequence of the dominance of pressure gradient current over the current associated with the magnetic field line curvature and particle anisotropy. copyright American Geophysical Union 1987

  14. New forecasting methods of the intensity and time development of geomagnetic and ionospheric storms

    NASA Astrophysics Data System (ADS)

    Akasofu, S.-I.

    The main phase of a geomagnetic storm develops differently from one storm to another. A description is given of the solar wind quantity which controls directly the development of the main phase of geomagnetic storms. The parameters involved include the solar wind speed, the magnetic field intensity, and the polar angle of the solar wind magnetic field projected onto the dawn-dusk plane. A redefinition of geomagnetic storm and auroral activity is given. It is pointed out that geomagnetic disturbances are caused by the magnetic fields of electric currents which are generated by the solar wind-magnetosphere dynamo. Attention is given to approaches for forecasting the occurrence and intensity of geomagnetic storms and ionospheric disturbances.

  15. Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes

    NASA Technical Reports Server (NTRS)

    Kane, R. P.; Trivedi, N. B.

    1981-01-01

    Computations concerning variations of the geomagnetic field at MAGSAT altitudes were investigated. Using MAGSAT data for the X, Y, and Z components of the geomagnetic field, a computer conversion to yield the H component was performed. Two methods of determining delta H normalized to a constant geocentric distance R sub 0 = 6800 were investigated, and the utility of elta H at times of magnetic storms was considered. Delta H at a geographical latitude of 0 at dawn and dusk, the standard Dst, and K sub p histograms were plotted and compared. Magnetic anomalies are considered. Examination of data from the majority of the 400 passes of MAGSAT considered show a reasonable delta H versus latitude variation. Discrepancies in values are discussed.

  16. Ionospheric Behaviors Over Korea Peninsula During the Super Geomagnetic Storm Using GPS Measurements

    NASA Astrophysics Data System (ADS)

    Chung, Jong-Kyun; Choi, Byung-Kyu; Baek, Jungho; Jee, Geonhwa; Cho, Jungho

    2009-12-01

    The super-geomagnetic storms called 2003 Halloween event globally occurred during the period of 29 through 31 which are the following days when the solar flares of X18 class exploded on 28 October 2003. The S4 index from GPS signal strength and the peak electron density (NmF2) from GPS tomography method are analyzed according to the date. The occurrences of the cycle slip and scintillation in the GPS signals are 1,094 and 1,387 on 28 and 29 October, respectively and these values are higher than 604 and 897 on 30 and 31 October. These mean the ionospheric disturbances are not always generated by the period of geomagnetic storm. Therefore, GPS S4 index is useful to monitor the ionospheric disturbances. Behaviors of ionospheric electron density estimated from GPS tomography method are analyzed with the date. At UT = 18 hr, the maximum NmF2 is shown on 28 October. It agrees with NmF2 variation measured from Anyang ionosonde, and the GPS signal are better condition on 30 and 31 October than 28 October. In conclusion, GPS signal condition is relation with geomagnetic activities, and depend upon the variation of the electron density. We will study the long-term data to examine the relationship between the GPS signal quality and the electron density as the further works.

  17. Active experiments in the ionosphere and geomagnetic field variations

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  18. Interplanetary magnetic field and geomagnetic Dst variations.

    NASA Technical Reports Server (NTRS)

    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.

  19. Moderate Geomagnetic Storms: Interplanetary Origins and Coupling Functions (ISEE3 Data)

    NASA Technical Reports Server (NTRS)

    Mendes, Odim, Jr.; Gonzalez, W. D.; Gonzalez, A. L. C.; Pinto, O., Jr.; Tsurutani, B. T.

    1996-01-01

    Geomagnetic storms are related to the ring current intensification, 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 (-100nT is less or equal to Dst(sub peak) is less than or equal to -50 nT) and analyzed the coupling processes during the storm main phase at solar maximum (1978-1979).

  20. Fluctuations in tides and geomagnetic variations

    NASA Astrophysics Data System (ADS)

    Kohsiek, A.; Kiefer, M.; Meek, C. E.; Manson, A. H.

    Middle atmosphere tidal winds and the daily geomagnetic Sq-variation show a day-to-day variability, both with a local behaviour. Due to the main cause of the Sq-variation, the ionospheric dynamo effect, day-to-day fluctuation of Sq could be raised by fluctuations in tides. This coupling of fluctuations is investigated with radar wind data measured at Saskatoon at around 100 km height and with magnetic data from four observatories in the vicinity of the radar. We show that our definition of fluctuations exhibits properties of atmospheric tides in the winds and that the magnetic data can be assumed to represent a local behaviour. We find that there are some significant correlations between fluctuations in winds and magnetic variations. Apparently the local fluctuation of geomagnetic variations is weakly coupled not only to the fluctuations of the semidiurnal tides but also to those of the mean winds.

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

    NASA Astrophysics Data System (ADS)

    Berényi, Kitti Alexandra; Barta, Veronika; Kis, Arpad

    2016-07-01

    Geomagnetic storms affect the ionospheric regions of the terrestrial upper atmosphere through different physical and atmospheric processes. The phenomena that can be regarded as a result of these processes, generally is named as "ionospheric storm". The processes depend on altitude, segment of the day, the geomagnetic latitude and longitude, strength of solar activity and the type of the geomagnetic storm. We examine the data of ground-based radio wave ionosphere sounding measurements of European ionospheric stations (mainly the data of Nagycenk Geophysical Observatory) in order to determine how and to what extent a geomagnetic disturbance of a certain strength affects the mid-latitude ionospheric regions in winter and in summer. For our analysis we used disturbed time periods between November 2012 and June 2015. Our results show significant changing of the ionospheric F2 layer parameters on strongly disturbed days compared to quiet ones. We show that the critical frequencies (foF2) increase compared to their quiet day value when the ionospheric storm was positive. On the other hand, the critical frequencies become lower, when the storm was negative. In our analysis we determined the magnitude of these changes on the chosen days. For a more complete analysis we compare also the evolution of the F2 layer parameters of the European ionosonde stations on a North-South geographic longitude during a full storm duration. The results present the evolution of an ionospheric storm over a geographic meridian. Furthermore, we compared the two type of geomagnetic storms, namely the CME caused geomagnetic storm - the so-called Sudden impulse (Si) storms- and the HSS (High Speed Solar Wind Streams) caused geomagnetic storms -the so-called Gradual storms (Gs)- impact on the ionospheric F2-layer (foF2 parameter). The results show a significant difference between the effect of Si and of the Gs storms on the ionospheric F2-layer.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  4. Database of ion temperature maps during geomagnetic storms.

    PubMed

    Keesee, Amy M; Scime, Earl E

    2015-02-01

    Ion temperatures as a function of the x and y axes in the geocentric solar magnetospheric (GSM) coordinate system and time are available for 76 geomagnetic storms that occurred during the period July 2008 to December 2013 on CDAWeb. The method for mapping energetic neutral atom data from the Two Wide-angle Imaging Spectrometers (TWINS) mission to the GSM equatorial plane and subsequent ion temperature calculation are described here. The ion temperatures are a measure of the average thermal energy of the bulk ion population in the 1-40 keV energy range. These temperatures are useful for studies of ion dynamics, for placing in situ measurements in a global context, and for establishing boundary conditions for models of the inner magnetosphere and the plasma sheet.

  5. The geomagnetic storm of 1910 May 18 and the tail of Halley's Comet

    NASA Astrophysics Data System (ADS)

    Yan, L.-S.; Li, Z.-Y.; Gu, S.-Y.

    1984-09-01

    On May 18, 1910, the Lu-Kia-Pang Observatory near Shanghai recorded a geomagnetic storm, but it was thought that this storm was not connected with the tail of Halley's comet. In the present paper, it is argued that this storm, rather than originating in some solar activity (coronal hole or solar flare), could have been the result of the interaction of the plasma tail of Halley's comet and the earth's magnetosphere. The time lag between the storm and the transit as calculated by Leuchner (1910) is given, and the characteristic features of cometary tails and the mechanisms by which they produce geomagnetic storms are analyzed.

  6. Driving Plasmaspheric Electron Density Simulations During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  7. Geomagnetic secular variation in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Heirtzler, J. R.; Nazarova, K.

    2003-02-01

    Annual repeat stations in Australia and in South Africa show that secular variation may change rapidly and over short geographical distances in the Indian Ocean area. Satellite models show large secular variations in the center of the Indian Ocean where there are few island geomagnetic observatories. This paper investigates marine geomagnetic measurements to see if they give more information about secular variations in this area. Between 1960 and 1988 there were more than 70 port-to-port cruises with ships towing proton precession magnetometers in the Indian Ocean. Change in field intensity from one cruise to another provides new information about the secular variation in this part of the world. Several methods were investigated to determine this change from the ship's data. Observing the change on closely parallel or crossing tracks provides an estimate of this change. These results indicate that there are short time and distance scales of secular variation in the Indian Ocean which have not been accounted for in geomagnetic field models.

  8. Solar generated quasi-biennial geomagnetic variation

    NASA Technical Reports Server (NTRS)

    Sugiura, M.; Poros, D. J.

    1977-01-01

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

  9. Why are intense geomagnetic storms so important for human life?

    NASA Astrophysics Data System (ADS)

    Saiz, E.; Cerrato, E.; Cid, C.; Aguado, J.

    2008-12-01

    Increasing knowledge concerning the space environment surrounding the earth has become one of the main focuses of research. This is mainly due to the fact that the adverse conditions in near-earth space cause significant damage to technological systems and, consequently, considerable economic losses. Many types of space weather-related anomalies and failings have been identified in recent years, thus converting adverse space weather into one of the threats facing modern human technology. Therefore important efforts should be made to find technical and operational solutions to space weather problems. In this framework, the need to implement reliable real-time warning tools is evident. Meanwhile, the fewer parameters involved in making predictions, the more valuable the tools will be. The present work develops a warning procedure based on the use of the z component of the interplanetary magnetic field only. The aim of this tool is to warn of the occurrence of intense geomagnetic variations, as measured by the geomagnetic Dst index. A comparison of our results with those criteria available in the relevant literature for the occurrence of intense geomagnetic activity shows a significant improvement in alerting capability.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Modeling geomagnetic storms on prompt and diffusive time scales

    NASA Astrophysics Data System (ADS)

    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 <400~MeV/G, but peaks in phase space density observed by the ECT instrument suite at higher first invariant are not reproduced by radial transport from a source at higher L. A 3D guiding center code with plasmasheet injection is used to simulate particle motion in time-dependent MHD fields calculated from the Lyon-Fedder-Mobarry global MHD code, as an extension of the Hudson et al. (2012) study of the Whole Heliosphere Interval of CIR-driven storms in March-April 2008. Direct comparison with measured fluxes at GOES show improved comparison with observations relative to

  12. Composition change and its effect on mass density response during geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Liu, X.; Thayer, J. P.; Wang, W.; Burns, A. G.; Sutton, E.

    2013-12-01

    Accelerometer data from coplanar orbits of CHAMP and GRACE satellites are used to study the complex altitude and latitude variations of the thermosphere mass density response to corotating interaction regions / high speed streams for the period of 01-10 December 2008 near 09 LT. The thermosphere neutral composition response to the energy input and the associated thermal expansion and vertical winds induced by the storm is investigated in this study. Helium number densities near 500 km were extracted from the CHAMP and GRACE measurements and, with three-degree latitude resolution, clearly show the presence of a winter hemisphere helium bulge. Helium estimates in the upper thermosphere during solar minimum have not been observed since the 1976 minimum. This recent extreme solar minimum indicates winter-time helium concentrations exceed NRL-MSISE00 estimates by 30%-70% during quiet geomagnetic activity after adjusting F10.7 input into MSIS. During active geomagnetic conditions, helium concentrations at GRACE altitudes decrease while oxygen concentrations increase. The perturbation in mass density from quiet to active conditions is found to be less enhanced in the winter hemisphere at the higher GRACE altitudes (25%) than at CHAMP altitudes (60%) and is attributed to dynamic behavior in the helium / oxygen transition. An investigation of the altitude structure in thermosphere mass density storm-time perturbations revealed the important effects of composition change with maximum perturbation occurring near the He/O transition region and a much weaker maximum occurring near the O/N2 transition region. A helium module has been implemented in the NCAR-TIEGCM model and simulations of mass density response to a geomagnetic storm for thermosphere conditions with and without helium will be presented.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Geomagnetic sudden impulses and storm sudden commencements - A note on terminology

    NASA Technical Reports Server (NTRS)

    Joselyn, J. A.; Tsurutani, B. T.

    1990-01-01

    The definitions of and distinctions between storm sudden commencements (SSCs) and geomagnetic sudden impulses (SIs) are examined and present definitions of SIs and SSCs are modernized. Quantitative definitions of the two terms are recommended.

  15. Substorms observations over Apatity during geomagnetic storms in the period 2012 - 2016

    NASA Astrophysics Data System (ADS)

    Guineva, Veneta; Werner, Rolf; Despirak, Irina; Kozelov, Boris

    2016-07-01

    In this work we studied substorms, generated during enhanced geomagnetic activity in the period 2012 - 2016. Observations of the Multiscale Aurora Imaging Network (MAIN) in Apatity have been used. Solar wind and interplanetary magnetic field parameters were judged by the 1-min sampled OMNI data base. Substorm onset and further development were verified by the 10-s sampled data of IMAGE magnetometers and by data of the all-sky camera at Apatity. Subject of the study were substorms occurred during geomagnetic storms. The so-called "St. Patrick's day 2015 event" (17-21 March 2015), the events on 17-18 March 2013 and 7-17 March 2012 (a chain of events generated four consecutive storms) which were among the events of strongest geomagnetic activity during the current solar cycle 24, were part of the storms under consideration. The behavior of the substorms developed during different phases of the geomagnetic storms was discussed.

  16. Biotropic geomagnetic pulsations Pc1 resulting from the magnetic storm of March 17, 2015

    NASA Astrophysics Data System (ADS)

    Slivinsky, A. P.

    2016-12-01

    Data obtained by a Hall sensor-based magnetic field detector have been used to record the spectral components of the geomagnetic field. An analysis of specific features of the spectral characteristics of geomagnetic fluctuations has indicated that the pulsations identified in the vicinity of the strong magnetic storm of March 17, 2015, are "pearl"-type fluctuations, i.e., biotropic geomagnetic Pc1 pulsations.

  17. A search for the interplanetary quantity controlling the development of geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1979-01-01

    An historical account is presented concerning the evolution of our present concept of geomagnetic storms. The present concept was formulated by Chapman (1927) in his magnetic data statistical studies of 'the initial rise' (now termed the initial phase) 'and subsequent larger decrease' (now termed the main phase) in H, followed by 'slow recovery'. The concept introduced by Alfven in 1940 of guiding center motions of a charged particle in a nonuniform magnetic field (ring currents) is also discussed. By 1963 it became quite certain that the ring current, namely a storm-time Van Allen belt, is formed in the magnetosphere during the storm's main phase. The search then began for the solar wind quantity controlling the development of the main phase. The author then gives a personal account of how our concept of geomagnetic storms has advanced and how new findings based on satellite and ground-based observations have made it possible to arrive at a first-approximation expression for the interplanetary quantity controlling the development of geomagnetic storms. Since a geomagnetic storm is a magnetic manifestation of a magnetospheric storm, which is a nonlinear superposition of intense magnetospheric substorms, the main emphasis is shifted toward the understanding of magnetospheric substorms in order to arrive at the parameters controlling the development of geomagnetic storms.

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

    PubMed

    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.

  19. Modeling the dynamics of the inner magnetosphere during strong geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Tsyganenko, N. A.; Sitnov, M. I.

    2005-03-01

    This work builds on and extends our previous effort (Tsyganenko et al., 2003) to develop a dynamical model of the storm-time geomagnetic field in the inner magnetosphere, using space magnetometer data taken during 37 major events in 1996-2000 and concurrent observations of the solar wind and interplanetary magnetic field (IMF). The essence of the approach is to derive from the data the temporal variation of all major current systems contributing to the distant geomagnetic field during the entire storm cycle, using a simple model of their growth and decay. Each principal source of the external magnetic field (magnetopause, cross-tail current sheet, axisymmetric and partial ring currents, and Birkeland current systems) is driven by a separate variable, calculated as a time integral of a combination of geoeffective parameters NλVβBsγ, where N, V, and Bs are the solar wind density, speed, and the magnitude of the southward component of the IMF, respectively. In this approach we assume that each source has its individual relaxation timescale and residual quiet-time strength, and its partial contribution to the total field depends on the entire history of the external driving of the magnetosphere during a storm. In addition, the magnitudes of the principal field sources were assumed to saturate during extremely large storms with abnormally strong external driving. All the parameters of the model field sources, including their magnitudes, geometrical characteristics, solar wind/IMF driving functions, decay timescales, and saturation thresholds, were treated as free variables, and their values were derived from the data. As an independent consistency test, we calculated the expected Dst variation on the basis of the model output at Earth's surface and compared it with the actual observed Dst. A good agreement (cumulative correlation coefficient R = 0.92) was found, in spite of the fact that ˜90% of the spacecraft data used in the fitting were taken at synchronous orbit

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Nikitina, Lidia; Trichtchenko, Larisa; Boteler, David

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  3. Some properties of trans-equatorial ion whistlers observed by Isis satellites during geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Watanabe, S.; Ondoh, T.

    1986-01-01

    Several ion whistlers were observed by the polar orbiting satellites, Isis, during geomagnetic storms associated with large solar flares in 1982. It seems that the proton density ratio to the total ions deduced from the crossover frequency of the transequatorial ion whistlers observed at geomagnetic low latitudes during the main phase of the geomagnetic storm on July 14, 1982 was lower than the usual density ratio. An anomalous pattern seen on the time-compressed dynamic spectra of the ion whistlers on September 6, 1982 may suggest the existence of effects by the component He(3+) in a quite small amount.

  4. Mid-latitude Ionospheric Disturbances Due to Geomagnetic Storms at ISS Altitudes

    NASA Astrophysics Data System (ADS)

    Minow, J. I.; Willis, E. M.; Parker, L. N.

    2014-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  6. Determination of a geomagnetic storm and substorm effects on the ionospheric variability from GPS observations at high latitudes

    NASA Astrophysics Data System (ADS)

    Gómez, Luis; Ignacio Sabbione, Juan; Andrea van Zele, María; Meza, Amalia; Brunini, Claudio

    2007-06-01

    The aim of this work is to characterize the ionospheric electron content variability during a standard and simple geomagnetic storm, and substorms during it. The analysis is based on tying the geomagnetic disturbances including the signatures of the current wedge formed during the substorm expansion phase, with the variability of ionospheric vertical total electron content (VTEC) in local time; for this reason the VTEC is computed for complete geographical longitude coverage at subauroral and auroral latitudes. The study is based on the geomagnetic storm befallen on April 6 and 7, 2000 (near the equinox) and the TEC are computed from global positioning system (GPS). The main results can be divided into three groups: (a) when the geomagnetic storm starts between pre-midnight and dawn, a minimum of VTEC is recorded, lasting all the long day (ionospheric storm negative phase); also the nighttime electron content may decrease below the corresponding for quiet days; but near the 60 of geomagnetic latitude the ionization polar tongue can be observed at noon, superimposed to the negative phase; (b) computed by GPS stations placed lower than 50, when the geomagnetic storm starts between dawn and noon the VTEC recorded a positive phase, but if it starts at noon a dusk effect is recorded; those located between 50 and 60 show a sudden increase and later sudden decrease to nocturnal values, (c) when the geomagnetic storm starts between afternoon and sunset, at stations located lower than 50 a dusk effect and an ionospheric negative phase during the next day are recorded, but if the GPS stations are located at higher latitude than 50 the VTEC representation shows the nocturnal end of the ionization polar tongue. Expansion phases of substorms are shown as small VTEC variations recorded for a short time: decreases if the substorm happens between dawn and midday; enhancements during the fall of the ionospheric positive phase. From the comparison with the results obtained by other

  7. Comparison of outliers and novelty detection to identify ionospheric TEC irregularities during geomagnetic storm and substorm

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    In this study, we compare two learning mechanisms: outliers and novelty detection in order to detect ionospheric TEC disturbance by November 2004 geomagnetic storm and January 2005 substorm. The mechanisms are applied by using v-SVR learning algorithm which is a regression version of SVM. Our results show that both mechanisms are quiet accurate in learning TEC data. However, novelty detection is more accurate than outliers detection in extracting anomalies related to geomagnetic events. The detected anomalies by outliers detection are mostly related to trend of data, while novelty detection are associated to geomagnetic events. Novelty detection also shows evidence of LSTID during geomagnetic events.

  8. Data-based Modeling of the Dynamical Inner Magnetosphere During Strong Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Tsyganenko, N.; Sitnov, M.

    2004-12-01

    This work builds on and extends our previous effort [Tsyganenko et al., 2003] to develop a dynamical model of the storm-time geomagnetic field in the inner magnetosphere, using space magnetometer data taken during 37 major events in 1996--2000 and concurrent observations of the solar wind and IMF. The essence of the approach is to derive from the data the temporal variation of all major current systems contributing to the geomagnetic field during the entire storm cycle, using a simple model of their growth and decay. Each principal source of the external magnetic field (magnetopause, cross-tail current sheet, axisymmetric and partial ring currents, Birkeland currents) is controlled by a separate driving variable that includes a combination of geoeffective parameters in the form Nλ Vβ Bsγ , where N, V, and Bs are the solar wind density, speed, and the magnitude of the southward component of the IMF, respectively. Each source was also assumed to have an individual relaxation timescale and residual quiet-time strength, so that its partial contribution to the total field was calculated for any moment as a time integral, taking into account the entire history of the external driving of the magnetosphere during each storm. In addition, the magnitudes of the principal field sources were assumed to saturate during extremely large storms with abnormally strong external driving. All the parameters of the model field sources, including their magnitudes, geometrical characteristics, solar wind/IMF driving functions, decay timescales, and saturation thresholds were treated as free variables, to be derived from the data by the least squares. The relaxation timescales of the individual magnetospheric field sources were found to largely differ between each other, from as large as ˜30 hours for the symmetrical ring current to only ˜50 min for the region~1 Birkeland current. The total magnitudes of the currents were also found to dramatically vary in the course of major storms

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

    NASA Technical Reports Server (NTRS)

    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

  10. Ionospheric Behavior During the First Few Hours of Intense Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Mannucci, Anthony J.; Crowley, Geoff; Tsurutani, Bruce; Fuller-Rowell, Tim

    2006-01-01

    The behavior of the ionosphere during the first few hours of intense geomagnetic storms is presented. The topics include: 1) TEC Modification; 2) JASON TEC (1336 km altitude); 3) Multiple Storms; 4) CHAMP (greater than 400 km) November 20, 2003; 5) November 20, 1PM LT, Ground; 6) Role of Modeling; and 7) Composition-related increase.

  11. Historical variation of the geomagnetic axial dipole

    NASA Astrophysics Data System (ADS)

    Finlay, Christopher C.

    2008-09-01

    The geomagnetic axial dipole (hereinafter denoted g10) is the largest component of our planet's magnetic field. Its magnitude determines the morphology of solar-terrestrial electrical current systems and it is the most fundamental diagnostic property of the core-generated geodynamo. Elucidating past and future variations of g10(t) is consequently of central importance in geomagnetism. Previous historical geomagnetic field models, such as gufm1 of Jackson et al. [Jackson, A., Jonkers, A.R.T., Walker, M.R., 2000. Four centuries of geomagnetic secular variation from historical records. Philos. Trans. R. Soc. Lond. A 358, 957-990], used direct observations to constrain g10(t) only after 1840 A.D.; before this time a crude linear extrapolation of the post-1840 A.D. rate of change (15 nT/year) was employed. In this contribution I construct historical field models with g10(t) instead constrained from 1590 A.D. to 1840 A.D. by an archaeointensity dataset compiled by Korte et al. [Korte, M., Genevey, A., Constable, C.G., Frank, U., Schnepp, E., 2005. Continuous geomagnetic field models for the past 7 millennia. 1. A new global data compilation. Geochem. Geophys. Geosyst. 6, doi:10.1029/2004GC000800]. A range of possible linear models of the form g10(t)=g10(1840)+β(t-1840) are first explored; β=2.74±42.32 nT/year is found to explain the archaeointensity dataset with maximum likelihood, consistent with the recent findings of Gubbins et al. [Gubbins, D., Jones, A.L., Finlay, C.C., 2006. Fall in Earth's magnetic field is erratic. Science 312, 900-902]. Relaxing the linear constraint in an effort to find more physically plausible models, I find it is necessary to artificially increase the weight given to the archaeointensity data in order to obtain acceptable models. Despite satisfactorily explaining both the historical and archaeointensity data, and possessing reasonable spatial and temporal complexity, such free evolution models perform worse than the simpler linearly

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

    NASA Astrophysics Data System (ADS)

    Bhatt, A.; Kendall, E. A.

    2015-12-01

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

  13. Comparison of CME and CIR driven geomagnetic storms using the artificial neural network model

    NASA Astrophysics Data System (ADS)

    Revallo, Milos; Valach, Fridrich; Hejda, Pavel; Bochnicek, Josef

    2016-04-01

    A model of geomagnetic storms based on the method of artificial neural networks (ANN) combined with an analytical approach is presented in the paper. Unlike our previous studies, here we focus on medium and weak geomagnetic storms caused by coronal mass ejections (CMEs) and those caused by corotating interaction regions (CIRs). As the model input, the hourly solar wind parameters measured by the ACE satellite at the libration point L1 are used. The time series of the Dst index is obtained as the model output. The simulated Dst index series is compared with the corresponding observatory data. The resulting Dst index series are inspected and typical features of CME and CIR driven storms are isolated. The model reliabilty is assessed using the skill scores, namely the correlation coefficient CC and the prediction efficiency PE. The general observation is that in the case of medium and weak geomagnetic storms the model performance is worse than in the case of intense geomagnetic storms studied in our previous paper. Due to more complex Dst index record, the model response for CIR driven storms is worse than in the case of CME driven storms.

  14. Reduction of the field-aligned potential drop in the polar cap during large geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Kitamura, N.; Seki, K.; Nishimura, Y.; Hori, T.; Terada, N.; Ono, T.; Strangeway, R. J.

    2013-12-01

    We have studied photoelectron flows and the inferred field-aligned potential drop in the polar cap during 5 large geomagnetic storms that occurred in the periods when the photoelectron observations in the polar cap were available near the apogee of the FAST satellite (~4000 km) at solar maximum, and the footprint of the satellite paths in the polar cap was under sunlit conditions most of the time. In contrast to the ~20 V potential drop during geomagnetically quiet periods at solar maximum identified by Kitamura et al. [JGR, 2012], the field-aligned potential drop frequently became smaller than ~5 V during the main and early recovery phases of the large geomagnetic storms. Because the potential acts to inhibit photoelectron escape, this result indicates that the corresponding acceleration of ions by the field-aligned potential drop in the polar cap and the lobe region is smaller during the main and early recovery phases of large geomagnetic storms compared to during geomagnetically quiet periods. Under small field-aligned current conditions, the number flux of outflowing ions should be nearly equal to the net escaping electron number flux. Since ions with large flux originating from the cusp/cleft ionosphere convect into the polar cap during geomagnetic storms [e.g., Kitamura et al., JGR, 2010], the net escaping electron number flux should increase to balance the enhanced ion outflows. The magnitude of the field-aligned potential drop would be reduced to let a larger fraction of photoelectrons escape.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    In this work we have investigated the global ionospheric response to geomagnetic storm on May 2-3, 2010 using GSM TIP (Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere) simulation results. In the GSM TIP storm time model runs, several input parameters such as cross-polar cap potential difference and R2 FAC (Region 2 Field-Aligned Currents) varied as a function of the geomagnetic activity AE-index. Current simulation also uses the empirical model of high-energy particle precipitation by Zhang and Paxton. In this model, the energy and energy flux of precipitating electrons depend on a 3 hour Kp-index. We also have included the 30 min time delay of R2 FAC variations with respect to the variations of cross-polar cap potential difference. In addition, we use the ground-based ionosonde data for comparison our model results with observations. We present an analysis of the physical mechanisms responsible for the ionospheric effects of geomagnetic storms. The obtained simulation results are used by us as a medium for HF radio wave propagation at different latitudes in quiet conditions, and during main and recovery phase of a geomagnetic storm. To solve the problem of the radio wave propagation we used Zakharov's (I. Kant BFU) model based on geometric optics. In this model the solution of the eikonal equation for each of the two normal modes is reduced using the method of characteristics to the integration of the six ray equation system for the coordinates and momentum. All model equations of this system are solved in spherical geomagnetic coordinate system by the Runge-Kutta method. This model was tested for a plane wave in a parabolic layer. In this study, the complex refractive indices of the ordinary and extraordinary waves at ionospheric heights was calculated for the first time using the global first-principal model of the thermosphere-ionosphere system that describes the parameters of an inhomogeneous anisotropic medium during a

  16. Positive and negative ionospheric storms occurring during the 15 May 2005 geomagnetic superstorm

    NASA Astrophysics Data System (ADS)

    Horvath, Ildiko; Lovell, Brian C.

    2015-09-01

    This study focuses on the 15 May 2005 geomagnetic superstorm and aims to investigate the global variation of positive and negative storm phases and their development. Observations are provided by a series of global total electron content maps and multi-instrument line plots. Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe) simulations are also employed. Results reveal some sunward streaming plumes of storm-enhanced density (SED) over Asia and a well-developed midlatitude trough over North America forming isolated positive and negative storms, respectively. The simultaneous development of positive and negative storms over North America is also shown. Then, some enhanced auroral ionizations maintained by strong equatorward neutral winds appeared in the depleted nighttime ionosphere. Meanwhile, the northern nighttime polar region became significantly depleted as the SED plume plasma could not progress further than the dayside cusp. Oppositely, a polar tongue of ionization (TOI) developed in the daytime southern polar region. According to CTIP simulations, solar heating locally maximized (minimized) over the southern (northern) magnetic pole. Furthermore, strong upward surges of molecular-rich air created O/N2 decreases both in the auroral zone and in the trough region, while some SED-related downward surges produced O/N2 increases. From these results we conclude for the time period studied that (1) composition changes contributed to the formation of positive and negative storms, (2) strengthening polar convection and increasing solar heating of the polar cap supported polar TOI development, and (3) a weaker polar convection and minimized solar heating of the polar cap aided the depletion of polar plasma.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Study on geomagnetic storms driving motion of 0.1-2 MeV radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenxia; Li, Xinqiao

    2016-08-01

    accelerating processes responsible for spectral index variations in different L regions during geomagnetic storms.

  19. Forecast of geomagnetic storms using CME parameters and the WSA-ENLIL model

    NASA Astrophysics Data System (ADS)

    Moon, Y.; Lee, J.; Jang, S.; Na, H.; Lee, J.

    2013-12-01

    Intense geomagnetic storms are caused by coronal mass ejections (CMEs) from the Sun and their forecast is quite important in protecting space- and ground-based technological systems. The onset and strength of geomagnetic storms depend on the kinematic and magnetic properties of CMEs. Current forecast techniques mostly use solar wind in-situ measurements that provide only a short lead time. On the other hand, techniques using CME observations near the Sun have the potential to provide 1-3 days of lead time before the storm occurs. Therefore, one of the challenging issues is to forecast interplanetary magnetic field (IMF) southward components and hence geomagnetic storm strength with a lead-time on the order of 1-3 days. We are going to answer the following three questions: (1) when does a CME arrive at the Earth? (2) what is the probability that a CME can induce a geomagnetic storm? and (3) how strong is the storm? To address the first question, we forecast the arrival time and other physical parameters of CMEs at the Earth using the WSA-ENLIL model with three CME cone types. The second question is answered by examining the geoeffective and non-geoeffective CMEs depending on CME observations (speed, source location, earthward direction, magnetic field orientation, and cone-model output). The third question is addressed by examining the relationship between CME parameters and geomagnetic indices (or IMF southward component). The forecast method will be developed with a three-stage approach, which will make a prediction within four hours after the solar coronagraph data become available. We expect that this study will enable us to forecast the onset and strength of a geomagnetic storm a few days in advance using only CME parameters and the physics-based models.

  20. Data-Model Comparisons of Plasma Sheet Ion Temperatures during Moderate Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Keesee, A. M.; Ilie, R.; Liemohn, M. W.; Trigo, B.; Robison, G.; Carr, J., Jr.

    2014-12-01

    Ion heating occurs during geomagnetic storms as a result of many physical processes, including magnetic reconnection and adiabatic heating. Ion temperatures calculated from TWINS energetic neutral atom (ENA) data provide a global view of regions of heated ions in the plasma sheet. Two storms of similar, moderate magnitude are analyzed, a coronal mass ejection (CME)-driven storm that occurred on 26 September 2011 and a high speed stream (HSS)-driven storm on 13 October 2012. We present a comparison of the ion temperatures during the storms to patterns observed in a superposed epoch analysis of ion temperatures [Keesee et al., 2013] and compare the October storm to a previously analyzed HSS-driven storm [Keesee et al., 2012]. We also present a comparison of observed ion temperatures to those calculated from a simulation of each storm using the Space Weather Modeling Framework, including the BATS-R-US MHD model coupled with the HEIDI inner magnetosphere model.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Constable, Catherine; Parker, Robert L.

    1993-01-01

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

  3. Numerical Simulations of the Ring Current During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Chen, M. W.; Lemon, C.; Guild, T. B.; Schulz, M.; Roeder, J. L.; Lui, A.; Keesee, A. M.; Goldstein, J.; Le, G.; Rodriguez, J. V.

    2012-12-01

    Recent progress in ring current modeling has shown the importance of a self-consistent treatment of particle transport along with magnetic and electric fields in the inner magnetosphere. The ring current intensity and spatial distribution are significantly affected by variations in the plasma sheet (the major source to the ring current), the cross polar cap potential, and compressions and expansions of the magnetosphere. We simulate the ion and electron ring current and plasma sheet by using the magnetically and electrically self-consistent Rice Convection Model-Equilibrium [Lemon et al., JGR, 2004] with a time-varying magnetopause driven by upstream solar wind and interplanetary magnetic (IMF) conditions and with time-varying plasma sheet distributions as boundary conditions. Examples of detailed comparisons of simulated storm events with in-situ magnetic intensities (e. g., GOES, Polar/MPA, or THEMIS) and proton flux spectra (e. g., LANL/MPA and SOPA, Polar/CAMMICE, or THEMIS) and energetic neutral atom (ENA) fluxes (e. g., TWINS) will be shown. We will also present comparisons of observed electron flux spectra with simulations based on a few simple electron loss models. These data-model comparisons test the ability of our model to characterize the ring current environment and the storm-time inner magnetospheric magnetic field.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Olabode, Ayomide; Ariyibi, Emmanuel

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Radio signal anomalies detected with MEXART in 2012 during the recovery phase of geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Carrillo-Vargas, Armando; Pérez-Enríquez, Román; López-Montes, Rebeca; Rodríguez-Martínez, Mario; Ugalde-Calvillo, Luis Gerardo

    2016-11-01

    In this work we present MEXART observations in 2012 from 17 radio sources in which we detected anomalies in the radio signal of these sources occurring during the recovery phase of some geomagnetic storms. We performed FFT and wavelet analysis of the radio signals during these periods and found that rather than IPS the anomalies seem to originate in the ionosphere, especially because of the frequencies at which they are observed. We discuss this results under the view that the source of the geomagnetic storm is no longer in the interplanetary medium.

  8. A theoretical study of thermospheric composition perturbations during an impulsive geomagnetic storm

    SciTech Connect

    Burns, A.G.; Killeen, T.L. ); Roble, R.G. )

    1991-08-01

    The compositional response of the neutral thermosphere to an impulsive geomagnetic storm has been investigated using a numerical simulation made with the National Center for Atmospheric Research thermospheric general circulation model (NCAR-TGCM). Calculated time-dependent changes in neutral thermospheric composition have been studied, together with detailed neutral parcel trajectories and other diagnostic information from the model, to gain a greater understanding of the physical mechanisms responsible for composition variability during geomagnetic storms and, in particular, to investigate the causes of the positive and negative ionospheric storm effects. The following principal results were obtained from this study. (1) Calculated perturbations in thermospheric composition following the onset of an impulsive geomagnetic storm were found to be in good qualitative agreement with the previous experimental statistical study of storm time thermospheric morphology by Proelss. (2) During the initial (onset) phase of the simulated storm, upward vertical winds occurred in the auroral zone and downward winds occurred in the central magnetic polar cap. (3) The largest perturbations in mass mixing ratio of nitrogen at F region altitudes were found to be associated with parcels of neutral gas that travelled through the cusp region and with parcels that were trapped within the auroral zone for a long time. (4) Storm time enhancements in {Psi}{sub N{sub 2}} were found to occur in the midnight and early morning sectors both within and equatorward of the auroral zone, and these were determined to be associated with the advective effects of the large antisunward polar cap neutral winds.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Similarities and differences in low-to-mid latitude geomagnetic indices during storms

    NASA Astrophysics Data System (ADS)

    Katus, R. M.; Liemohn, M. W.

    2012-12-01

    Several versions of low-to-middle latitude geomagnetic indices are examined with respect to a normalized timeline based on several key storm features. In particular, we examine the well-known Dst and SYM-H indices, as well as a few other more recently-developed storm-intensity indices. These superposed indices are quantitatively compared, using the bootstrap method to quantify the error analysis, and employing descriptive statistics and significance tests to assess the similarities and differences between them. The results are then categorized by storm intensity, storm phase, and solar wind driver. While the indices are highly correlated with each other, dramatic deviation between the indices exist at certain storm epoch times and for certain types of magnetic storms. In particular, the correlation degrades at storm peak and especially for more intense storms. These indices are compared against simulation results from the Hot Electron and Ion Drift Integrator (HEIDI) model, which has been run for every intense storm from the last solar cycle with several input and boundary condition settings. Current systems and magnetic perturbations from these simulation results, which are also scaled onto a normalized storm-based timeline and categorized by storm intensity, storm phase, and solar wind driver, are used to interpret the physical processes underlying the systematic differences in the various ground-based magnetometer indices.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. [Influence of geomagnetic storms on the balance of autonomic regulatory mechanisms].

    PubMed

    Chichinadze, G; Tvildiani, L; Kvachadze, I; Tarkhan-Mouravi, I

    2005-09-01

    The investigation aimed to evaluate autonomic regulatory mechanisms in practically healthy persons during the geomagnetically quiet periods and during geomagnetic storms. The examinations were conducted among the volunteer young men (n=64) 18-22 years of age. The autonomic function was studied on the basis of the heart rate variability. The geomagnetically quiet periods were considered when the value of the K-index was no more then 2 and a geomagnetic storm was considered when the value of the index was 5 and more. It is ascertained that in the both cases the basic statistical indices of the heart rate were identical. The analysis of R-R intervals spectral power gave the possibility to sort the persons examined into the three different groups. The data obtained allowed to suggest that geomagnetic storms influence human organisms through the vagus centers by means of their excitation. This phenomenon may be considered as a self-regulatory physiologic mechanism of the adaptive character. The analysis of the spectral power of R-R intervals may be considered as a sensitive method for the detection of the magnitolabile persons.

  14. Electromagnetic emissions and fine structures observed near main ionospheric trough during geomagnetic storms and their interactions

    NASA Astrophysics Data System (ADS)

    Przepiórka, Dorota; Marek, Michał; Matyjasiak, Barbara; Rothkaehl, Hanna

    2016-04-01

    Geomagnetic conditions triggered by the solar activity affect the ionosphere, its fine and global structures. Very intense magnetic storms substantially change the plasma density, concentration and circulation. Especially sensitive region is located near auroral oval, where most energy is deposited during geomagnetic storms. In this region and just below it, where the main ionospheric trough is located, we observe enhanced electromagnetic emissions in different frequency ranges. In particular the AKR-like (Auroral Kilometric Radiation) emissions are seen at frequencies of the order of hundreds of kHz in the ionosphere, just below the auroral oval. Analyzing spectrograms from DEMETER mission and comparing them with electron density measurements from DEMETER, we found that AKR-like emissions are seen near poleward wall of the main ionospheric trough, during geomagnetic storms. Main ionospheric trough is known as a turbulent region which properties change as the geomagnetic storm evolves. This work is an attempt to determine how the presence of the different emissions affect main ionospheric trough parameters such as location, width and depth. Data used in this study come from DEMETER and RELEC missions. This work was partly supported by NCN grant Rezonans 2012/07/B/ST9/04414.

  15. A theoretical study of thermospheric composition perturbations during an impulsive geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Burns, A. G.; Killeen, T. L.; Roble, R. G.

    1991-08-01

    A numerical simulation was performed using the NCAR thermospheric GCM (NCAR-TGCM) and was used to investigate the physical processes responsible for the thermospheric neutral compositional perturbations that were caused by forcings associated with an impulsive geomagnetic storm. The resulting compositional forcing terms and the compositional response were analyzed using the diagnostics processor described by Killeen and Roble (1984, 1986) and Burns et al. (1989). The results of the study are used to explain the respective roles of dynamics and diffusion in establishing the compositional morphology observed during the storm, which is, in turn, partly responsible for the negative phase of ionospheric storms.

  16. Geomagnetic Storm and Substorm effect on the total electron content using GPS at subauroral latitudes

    NASA Astrophysics Data System (ADS)

    Gomez, L.; Sabione, J. I.; van Zele, M. A.; Meza, A. M.; Brunini, C.

    The aim of this work is to characterize the ionospheric electron content variability during a geomagnetic storm and substorms during it This study is based on the vertical total electron content VTEC computed from global positioning system GPS GPS stations located at sub-auroral latitudes are taken into account for analyzing the signatures of the current wedge formed during the substorm expansion phase The study is focused on the geomagnetic storm befallen on April 6 and 7 2000 near the equinox Because our study is based on tying the geomagnetic disturbances with the variability of VTEC in local time the GPS stations are located at different geographic longitude The main results are a when the geomagnetic storm starts between pre-midnight and dawn a minimum of VTEC is recorded lasting all the long day ionospheric storm negative phase also the nighttime electron content may decrease below the corresponding for quiet days but near the 60z of latitude the ionization polar tongue can be observed at noon superimposed to the negative phase b the VTEC computed by GPS station placed lower than 50o recorded a positive phase when the geomagnetic storm starts between dawn and noon or a dusk effect if it starts at noon while those located between 50o and 60o show a sudden increase and later sudden decrease to nocturnal values c when it starts between afternoon and sunset the ionospheric negative phase is recorded during the next day and if the GPS station are located at higher latitude than 50o the VTEC representation shows the nocturnal end of the

  17. Forecasting Geomagnetic Storms and Solar Energetic Particle Events: the COMESEP Project

    NASA Astrophysics Data System (ADS)

    Crosby, N.; Veronig, A.; Robbrecht, E.; Vrsnak, B.; Vennerstrøm, S.; Malandraki, O.; Dalla, S.; Srivastava, N.; Hesse, M.; Odstrcil, D.

    2012-04-01

    COMESEP (COronal Mass Ejections and Solar Energetic Particles), funded by the European Union Framework 7 programme, is a three-year collaborative project that has been running for one year. Tools for forecasting geomagnetic storms and solar energetic particle (SEP) radiation storms are being developed under the project. By analysis of historical data, complemented by the extensive data coverage of solar cycle 23, the key ingredients that lead to magnetic storms and SEP events and the factors that are responsible for false alarms are being identified. To enhance our understanding of the 3D kinematics and interplanetary propagation of coronal mass ejections (CMEs), the structure, propagation and evolution of CMEs are being investigated. In parallel, the sources and propagation of SEPs are being examined and modeled. Based on the insights gained, and making use of algorithms for the automated detection of CMEs, forecasting tools for geomagnetic and SEP radiation storms are being developed and optimised. Validation and implementation of the produced tools into an operational Space Weather Alert system will be performed. Geomagnetic and SEP radiation storm alerts will be based on the COMESEP definition of risk. COMESEP is a unique cross-collaboration effort and bridges the gap between the SEP and CME scientific communities. For more information about the project, see the COMESEP website http://www.comesep.eu/ . This work has received funding from the European Commission FP7 Project COMESEP (263252).

  18. Energetic Electron Populations in the Magnetosphere During Geomagnetic Storms and Substorms

    NASA Technical Reports Server (NTRS)

    McKenzie, David L.; Anderson, Phillip C.

    2002-01-01

    This report summarizes the scientific work performed by the Aerospace Corporation under NASA Grant NAG5-10278, 'Energetic Electron Populations in the Magnetosphere during Geomagnetic Storms and Subsisting.' The period of performance for the Grant was March 1, 2001 to February 28, 2002. The following is a summary of the Statement of Work for this Grant. Use data from the PIXIE instrument on the Polar spacecraft from September 1998 onward to derive the statistical relationship between particle precipitation patterns and various geomagnetic activity indices. We are particularly interested in the occurrence of substorms during storm main phase and the efficacy of storms and substorms in injecting ring-current particles. We will compare stormtime simulations of the diffuse aurora using the models of Chen and Schulz with stormtime PIXIE measurements.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. An empirical probability density distribution of planetary ionosphere storms with geomagnetic precursors

    NASA Astrophysics Data System (ADS)

    Gulyaeva, Tamara; Stanislawska, Iwona; Arikan, Feza; Arikan, Orhan

    moderate geomagnetic storms occurred during 2013. Results are discussed in the paper. This study is supported by the joint grant of TUBITAK 112E568 and RFBR 13-02-91370-CT_a.

  1. SAMI3-RCM simulation of the 17 March 2015 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Huba, J. D.; Sazykin, S.; Coster, A.

    2017-01-01

    We present a self-consistent modeling study of the ionosphere-plasmasphere system response to the 17 March 2015 geomagnetic storm using the coupled SAMI3-RCM code. The novel feature of this work is that we capture the important storm time dynamics of the ionosphere on a global scale and its manifestation in the plasmasphere. We find that the penetration electric fields associated with the magnetic storm lead to a storm time enhanced density in the low- to middle-latitude ionosphere. We compare the modeled total electron content (TEC) with GPS-measured TEC in the American sector. Additionally, we observe the development of polar cap "tongues of ionization" and the formation of subauroral plasma streams in the postsunset, premidnight sector, and its impact on the plasmasphere. However, we did not see the development of plasmaspheric plumes during this event which we attribute to the long main phase of the storm (˜18 h).

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Global inospheric effects of the October 1989 geomagnetic storm

    SciTech Connect

    Yeh, K.C.; Lin, K.H.; Ma, S.Y.

    1994-04-01

    Based on a large data base from 40 ionosonde stations distributed worldwide and 12 total electron content stations, a case study is made on the global behavior of ionospheric responses to the great magnetic storm of October 1989. The magnetic storm was triggered by a solar flare with the largest class of X13/4B and started with a sudden storm commencement (ssc) at 0917 UT on October 20. After the initial phase the storm underwent two periods of maximum activities in the following 2 days. Low-latitude auroras were sighted and reported in widely separated areas in both northern and southern hemispheres. In response to these magnetic and auroral activities the ionosphere showed remarkable effects. Depending on the local time of ssc occurrence, the ionospheric response differed appreciably. Impressive changes were long-lasting, large-scale effects, such as the severe depressions of foF2 at higher latitudes, the temporary suppression of the equatorial anomaly and large horizontal gradients at certain latitudes. Also observed were positive storm effects of short duration during the post-sunset period in response to the onset of both ssc and main phase of the magnetic storm. These two positive storm effects showed different patterns suggesting different casual mechanisms. In addition, global propagation of large-scale traveling ionospheric disturbances (TIDs) was seen during 2 nights, identified by dramatic rises of h{prime}F with periodic fluctuations. The equatorward propagation velocities of the TIDs varied between 330 m/s and 680 m/s for the east Asia region. 33 refs., 16 figs., 1 tab.

  4. Impacts of Geomagnetic Storms on the Terrestrial H-Exosphere Using Twins-Lyman Stereo Data

    NASA Astrophysics Data System (ADS)

    Nass, U.; Zoennchen, J.; Fahr, H. J.; Goldstein, J.

    2015-12-01

    Based on continuously monitored Lyman-alpha data registered by the TWINS1/2-LAD instruments we have studied the impact of a weaker and a stronger geomagnetic storm on the exospheric H-density distribution between heights of 3--8 Earth-radii. As is well known, solar Lyman-alpha radiation is resonantly backscattered from geocoronal neutral hydrogen (H). The resulting resonance glow intensity in the optically thin regime is proportional to H column density along the line of sight (LOS). Here we present the terrestrial exospheric response to geomagnetic storms. We quantify the reaction to geomagnetic activity in form of amplitude and temporal response of the H-density, sampled at different geocentric distances. We find that even in case of a weak storm, the exospheric H-density in regions above the exobase reacts with a suprisingly large increase in a remarkably short time period of less than half a day. Careful analysis of this geomagnetic density effect indicates that it is an expansion in the radial scale height of the exospheric H-density, developing from exobasic heights.

  5. Geomagnetic disturbance intensity dependence on the universal timing of the storm peak

    NASA Astrophysics Data System (ADS)

    Katus, R. M.; Liemohn, M. W.; Keesee, A. M.; Immel, T. J.; Ilie, R.; Welling, D. T.; Ganushkina, N. Yu.; Perlongo, N. J.; Ridley, A. J.

    2016-08-01

    The role of universal time (UT) dependence on storm time development has remained an unresolved question in geospace research. This study presents new insight into storm progression in terms of the UT of the storm peak. We present a superposed epoch analysis of solar wind drivers and geomagnetic index responses during magnetic storms, categorized as a function of UT of the storm peak, to investigate the dependency of storm intensity on UT. Storms with Dst minimum less than -100 nT were identified in the 1970-2012 era (305 events), covering four solar cycles. The storms were classified into six groups based on the UT of the minimum Dst (40 to 61 events per bin) then each grouping was superposed on a timeline that aligns the time of the minimum Dst. Fifteen different quantities were considered: seven solar wind parameters and eight activity indices derived from ground-based magnetometer data. Statistical analyses of the superposed means against each other (between the different UT groupings) were conducted to determine the mathematical significance of similarities and differences in the time series plots. It was found that the solar wind parameters have no significant difference between the UT groupings, as expected. The geomagnetic activity indices, however, all show statistically significant differences with UT during the main phase and/or early recovery phase. Specifically, the 02:00 UT groupings are stronger storms than those in the other UT bins. That is, storms are stronger when the Asian sector is on the nightside (American sector on the dayside) during the main phase.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  7. Terrestrial Response to Eruptive Solar Flares: Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.

    1995-01-01

    During the interval of August 1979 - December 1979, 56 unambiguous fast forward shocks were identified using magnetic field and plasma data collected by the ISEE-3 spacecraft. Because this interval is a solar maximum we assume the streams causing these shocks are associated with coronal mass ejections and eruptive solar flares. For these shocks we shall describe the shock-storm relationship for the level of intense storms (Dst < -100 nT). Then, we will discuss the interplanetary structures that are associated with the large-amplitude and long-duration negative Bz fields, which are found in the sheath field and/or driver gas regions of the shock and are thought to be the main cause of the intense storms.

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip K.; Ogunmodimu, Olugbenga

    2016-07-01

    The amplitude and phase of VLF/LF radio signals are sensitive to changes in electrical conductivity of the lower ionosphere which imprints its signature on the Earth-ionosphere waveguide. This characteristic makes it useful in studying sudden ionospheric disturbances, especially those related to prompt X-ray flux output from solar flares and gamma ray bursts (GRBs). However, strong geomagnetic disturbance and storm conditions are known to produce large and global ionospheric disturbances, which can significantly affect VLF radio propagation in the D region of the ionosphere. In this paper, using the data of three propagation paths at mid-latitudes (40-54°), we analyse the trend in variation of aspects of VLF diurnal signal under varying solar and geomagnetic space environmental conditions in order to identify possible geomagnetic footprints on the D region characteristics. We found that the trend of variations generally reflected the prevailing space weather conditions in various time scales. In particular, the 'dipping' of mid-day signal amplitude peak (MDP) occurs after significant geomagnetic perturbed or storm conditions in the time scale of 1-2 days. The mean signal amplitude before sunrise (MBSR) and mean signal amplitude after sunset (MASS) also exhibit storm-induced dipping, but they appear to be influenced by event's exact occurrence time and the highly variable conditions of dusk-to-dawn ionosphere. We also observed few cases of the signals rise (e.g., MDP, MBSR or MASS) following a significant geomagnetic event. This effect may be related to storms associated phenomena or effects arising from sources other than solar origin. The magnitude of induced dipping (or rise) significantly depends on the intensity and duration of event(s), as well as the propagation path of the signal. The post-storm day signal (following a main event, with lesser or significantly reduced geomagnetic activity) exhibited a tendency of recovery to pre-storm day level. In the

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Relationship Between Human Physiological Parameters And Geomagnetic Variations Of Solar Origin

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.

    variations of solar origin. The examinations and analyses performed show that space weather prediction may be utilized for the purpose of pharmacological and regime measures to limit the adverse physiological reactions to geomagnetic storms.

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

    USGS Publications Warehouse

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

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  14. The Future of Geomagnetic Storm Predictions: Implications from Recent Solar and Interplanetary Observations

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Within the last 7-8 years, there has been a substantial growth in out knowledge of the solar and interplanetary causes of geomagnetic storms at Earth. This review article will not attempt to cover all of the work done during this period. This can be found elsewhere. Our emphasis here will be on recent efforts that expose important, presently unanswered questions that must be addressed and solved before true predictability of storms can be possible. Hopefully, this article will encourage some readers to join this effort and perhaps make major contributions to the field.

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

    PubMed

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

    2014-04-01

    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.

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

    PubMed Central

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

    2014-01-01

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

  17. Nighttime thermospheric-ionospheric coupling during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Fagundes, P. R.; Muella, M. T. A. H.; Bittencourt, J. A.; Sahai, Y.; Lima, W. L. C.; Becker-Guedes, F.; Pillat, V. G.

    The electrodynamics of the ionosphere in the tropical region presents various scientific aspects which remain subject of intensive investigations and debates by the scientific community During the year 2002 in a joint project between Universidade do Vale do Para i ba UNIVAP and Universidade Luterana do Brasil ULBRA a chain of three Canadian Digital Ionosondes CADIs was established nearly along the geomagnetic meridian direction for tropical ionospheric studies such as the generation and dynamics of ionospheric irregularities changes and response due to geomagnetic disturbances and thermosphere-ionosphere coupling in the Brazilian sector The locations of the three ionosonde stations are S a o Jos e dos Campos 23 2 o S 45 9 o W dip latitude 17 6 o S - under the Equatorial Ionospheric Anomaly Palmas 10 2 o S 48 2 o W dip latitude 5 5 o S -- near the magnetic equator and Manaus 2 9 o S 60 0 o W dip latitude 6 4 o N -- near the magnetic equator It should be pointed out that Palmas and Manaus are located on opposite side of the magnetic equator but both are south of the geographic equator The three CADIs work in time-synchronized mode and obtain ionograms every 5 minutes This unique configuration of the ionospheric sounding stations allowed us to study the F-region dynamics during disturbed periods in the months of August and September 2002 Then an extension of the servo model was used to infer the magnetic meridional component of the thermospheric neutral winds over the low latitude

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

    USGS Publications Warehouse

    Campbell, W.H.

    1996-01-01

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

  19. RELATIONSHIPs among Geomagnetic storms, interplanetary shocks, magnetic clouds, and SUNSPOT NUMBER during 1995-2012

    NASA Astrophysics Data System (ADS)

    Berdichevsky, D. B.; Lepping, R. P.; Wu, C. C.

    2015-12-01

    During 1995-2012 Wind recorded 168 magnetic clouds (MCs), 197 magnetic cloud-like structures (MCLs), and 358 interplanetary (IP) shocks. Ninety four MCs and 56 MCLs had upstream shock waves. The following features are found: (i) Averages of solar wind speed, interplanetary magnetic field (IMF), duration (<Δt>), strength of Bzmin, and intensity of the associated geomagnetic storm/activity (Dstmin) for MCs with upstream shock waves (MCSHOCK) are higher (or stronger) than those averages for the MCs without upstream shock waves (MCNO-SHOCK). (ii) The <Δt> of MCSHOCK events (≈19.6 hr) is 9% longer than that for MCNO-SHOCK events (≈17.9 hr). (iii) For the MCSHOCK events, the average duration of the sheath (<ΔtSHEATH>) is 12.1 hrs. These findings could be very useful for space weather predictions, i.e. IP shocks driven by MCs are expected to arrive at Wind (or at 1 AU) about ~12 hours ahead of the front of the MCs on average. (iv) The occurrence frequency of IP shocks is well associated with sunspot number (SSN). The average intensity of geomagnetic storms measured by for MCSHOCK and MCNOSHOCK events is -102 and -31 nT, respectively. The is -78, -70, and -35 nT for the 358 IP shocks, 168 MCs, and 197 MCLs, respectively. These results imply that IP shocks, when they occur with MCs/MCLs, must play an important role in the strength of geomagnetic storms. We speculate as to why this is so. Yearly occurrence frequencies of MCSHOCK and IP shocks are well correlated with solar activity (e.g., SSN). Choosing the right Dstmin estimating formula for predicting the intensity of MC-associated geomagnetic storms is crucial for space weather predictions.

  20. Comparisons of Several Coupling Functions during Moderate Geomagnetic Storms of SC23

    NASA Astrophysics Data System (ADS)

    Maris Muntean, Georgeta; Mierla, Marilena; Besliu-Ionescu, Diana; Talpeanu, Dana Camelia

    2016-07-01

    Understanding the evolution of the interplanetary parameters before a geomagnetic storm and how they relate to its magnitude should improve our perspective towards a better prediction of geo-effectiveness of the solar eruptive events. One important way to understand the evolution of a geomagnetic storm is by computing the quantity of energy that is transferred from the solar wind into the magnetosphere. There are several formulas (coupling functions) to estimate this transfer of energy. We selected moderate geomagnetic storms (-50 nT ≥ Dst ≥ -150 nT) that were produced by interplanetary coronal mass ejections throughout the solar cycle 23. We selected only the events which were clearly associated with a solar event (i.e. a coronal mass ejection) (see Richardson and Cane online catalogue). We will present here a comparative analysis between different coupling functions such as epsilon parameter (Akasofu, 1981) and Ein parameter (Wang et al., 2014). We will discuss how these coupling functions are related to the geoeffective interplanetary electric field Em (see e.g. - Kan and Lee, 1979) that we have computed for the selected events. We will focus on a detailed case study.

  1. An interplanetary cause of large geomagnetic storms: Fast forward shock overtaking preceding magnetic cloud

    NASA Astrophysics Data System (ADS)

    Wang, Y. M.; Ye, P. Z.; Wang, S.; Xue, X. H.

    2003-07-01

    In the event that occurred during October 3-6, 2000, at least one magnetosonic wave and one fast forward shock advanced into the preceding magnetic cloud (MC). By using the field and plasma data from the ACE and WIND spacecraft, we analyze the evolution of this event, including the characteristics and changes of the magnetic fields and plasma. At the rear part of the cloud, a large southward magnetic field is caused by a shock compression. The shock intensified a preexisting southward magnetic field. This increased the geoeffectiveness of this event and produced an intense geomagnetic storm with Dst = -175 nT. We also describe another event with a shock overtaking a MC on Nov. 6, 2001. A great geomagnetic storm of intensity Dst = 292 nT resulted. These observations are used to argue that shock compression of magnetic cloud fields is an important interplanetary cause of large geomagnetic storms. Our analyses suggest that the geoeffectiveness is related to the direction of preexisting magnetic fields, the intensity of overtaking shock, and the amount of shock penetration into the preceding MC.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Geomagnetic storm effects on the thermosphere and the ionosphere revealed by in situ measurements from OGO 6

    NASA Technical Reports Server (NTRS)

    Marubashi, K.; Reber, C. A.; Taylor, H. A., Jr.

    1976-01-01

    The temporal response of the densities of upper-atmospheric ion and neutral constituents to a particular geomagnetic storm is studied using simultaneous ion and neutral-composition data obtained by the OGO 6 satellite during consecutive orbits at altitudes greater than 400 km. The investigated constituents include H(+), O(+), N2, O, He, and H. Derivation of the H density is reviewed, and the main effects of the storm are discussed, particularly temporal and global variations in the densities. It is found that: (1) the H and He densities began to decrease near the time of sudden commencement, with the decrease amounting to more than 40% of the quiet-time densities during the maximum stage at high latitudes; (2) the O and N2 densities exhibited an overall increase which began later than the change in H and He densities; (3) the H(+) density decreased differently in two distinct regions separated near the low-latitude boundary of the light-ion trough; and (4) the O(+) density showed an increase during earlier stages of the storm and decreased only in the Northern Hemisphere during the recovery phase. Certain physical and chemical processes are suggested which play principal roles in the ionospheric response to the storm

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

    NASA Astrophysics Data System (ADS)

    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

    NASA Astrophysics Data System (ADS)

    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. Secular Variations of the Geomagnetic Field in Europe

    NASA Astrophysics Data System (ADS)

    Sas-Uhrynowski, A.; Welker, E.

    2009-09-01

    The international project MagNetE (Magnetic Net For Europe) was undertaken in 2003. The project has been accepted by the International Association of Geomagnetism and Aeronomy of the IUGG. The common research on the geomagnetic field space and time distribution in Europe, as well as collecting data and its analysis, constitutes the grounds for theoretical works on geomagnetic field models and their parameters. It is also the basis for studying the genesis of the geomagnetic field secular variations and its mechanism. The results of the project enable to increase the accuracy of models on the global, regional, and also on local scale. It has a vital meaning for the regions where the geomagnetic data are not available or, where the existing data, because of their low accuracy, cannot be used. Information about the secular variations of the geomagnetic field makes it possible to update the magnetic data, which is needed in navigation, topography, telecommunication, geology and geophysics and other domains. The enclosed maps of isopors presented have been compiled using the results of measuring campaigns in the years 2004-2006 together with the archive data. They show the secular variations of the magnetic declination D, the length H of the horizontal intensity vector and the lenght F of the total intensity vector of the geomagnetic field, in the intervals 1995-2000 and 2000-2005. The maps of isopors for Europe have been worked out using data from not only the magnetic observatories, but also from some hundred magnetic secular variation stations (repeated stations), located in 23 European countries. The secular variation differences between data obtained from terrestrial surveys and data from the IGRF model (International Geomagnetic Reference Field) have been presented in the form of maps and histograms. In several regions of Europe the unexpectedly large secular variation anomalies are visible. Anomalies of so high frequency and large amplitude cannot exist. They are

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Day-to-day variability of total content, peak density and slab thickness, and the ionospheric response to geomagnetic storms. Final report, Jun 86-Sep 90

    SciTech Connect

    Fox, M.W.

    1990-11-01

    The issue of day-to-day ionospherics is of ongoing concern to users of satellites, navigation systems, and hf radio communications, and the mechanisms behind the variations are of interest to researchers. This report attempts to satisfy those operational concerns with a physical perspective, by analyzing hourly ionospheric data and developing an operationally useful model of the variations that is discussed in terms of the underlying physical processes. We describe an analysis of day-to-day variations in the total electron content, maximum electron density and equivalent slab thickness using nearly two solar cycles of observations from the American sector at mid latitudes. The report begins by quantifying day-to-day variability of these three F-region parameters and by performing a detailed correlation analysis between them. Usefulness of statistical and persistence forecasts are discussed. Then follows a study of the response of the ionosphere to geomagnetic storms, as these are the times when the variations from day to day are greatest. We then define storm patterns in terms of the departures on each day from average conditions in a storm-affected period. The average ionospheric response under a variety of conditions is described qualitatively and numerically. Individual storm patterns and common storm-related features are studied to characterize each storm and to investigate dependencies and interdependencies. The physical processes governing the observed responses and attempts to model these numerically, as well as applications to modeling real-time day-to-day variations in an operational sense, are discussed.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  12. Equatorial noise emissions observed by the DEMETER spacecraft during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Němec, F.; Parrot, M.; Santolík, O.

    2016-10-01

    Equatorial noise emissions are electromagnetic waves routinely observed in the equatorial region of the inner magnetosphere at frequencies between the proton cyclotron frequency and the lower hybrid frequency. Their observations are, however, typically limited to radial distances larger than about 2RE. We use the data measured by the low-altitude DEMETER spacecraft (altitude of about 700 km) to confirm that during periods of enhanced geomagnetic activity, these emissions penetrate down to low radial distances and eventually become a dominant wave emission close to the proton cyclotron frequency in the equatorial region. Wave data obtained during six intense geomagnetic storms (Dst <- 100 nT) are analyzed. It is shown that during the analyzed time intervals, the daytime wave activity within about 20° from the geomagnetic equator is significantly enhanced, while the nightside wave activity shows a weaker increase at lower frequencies. Multicomponent wave data allow us to determine dayside wave propagation parameters. It is shown that the waves are nearly linearly polarized and their wave vector directions are almost perpendicular to the ambient Earth's magnetic field, as it has been previously observed for equatorial noise emissions. Finally, we analyze the dependence of the equatorial wave intensity at the proton cyclotron frequency on Dst and AE geomagnetic indices, and we demonstrate that the dayside wave intensity increases by as much as 3 orders of magnitude during severely disturbed periods.

  13. Magnetic Field Measurement on the C/NOFS Satellite: Geomagnetic Storm Effects in the Low Latitude Ionosphere

    NASA Technical Reports Server (NTRS)

    Le, Guan; Pfaff, Rob; Kepko, Larry; Rowland, Doug; Bromund, Ken; Freudenreich, Henry; Martin, Steve; Liebrecht, C.; Maus, S.

    2010-01-01

    The Vector Electric Field Investigation (VEFI) suite onboard the Communications/Navigation Outage Forecasting System (C/NOFS) spacecraft includes a sensitive fluxgate magnetometer to measure DC and ULF magnetic fields in the low latitude ionosphere. The instrument includes a DC vector measurement at 1 sample/sec with a range of +/- 45,000 nT whose primary objective is to provide direct measurements of both V x B and E x B that are more accurate than those obtained using a simple magnetic field model. These data can also be used for scientific research to provide information of large-scale ionospheric and magnetospheric current systems, which, when analyzed in conjunction with the C/NOFS DC electric field measurements, promise to advance our understanding of the electrodynamics of the low latitude ionosphere. In this study, we use the magnetic field data to study the temporal and local time variations of the ring currents during geomagnetic storms. We first compare the in situ measurements with the POMME (the POtsdam Magnetic Model of the Earth) model in order to provide an in-flight "calibration" of the data as well as compute magnetic field residuals essential for revealing large scale external current systems. We then compare the magnetic field residuals observed both during quiet times and during geomagnetic storms at the same geographic locations to deduce the magnetic field signatures of the ring current. As will be shown, the low inclination of the C/NOFS satellite provides a unique opportunity to study the evolution of the ring current as a function of local time, which is particularly insightful during periods of magnetic storms. This paper will present the initial results of this study.

  14. The geomagnetic secular variation S parameter: A mathematical artifact

    NASA Astrophysics Data System (ADS)

    Linder, J. M.; Gilder, S. A.

    2011-12-01

    Secular variation, the change in the Earth's magnetic field through time, reflects the energy state of the geodynamo. Secular variation is commonly quantified by the standard deviation of the angular distances of the virtual geomagnetic poles to their mean pole, known as the S value. The S value has long been thought to exhibit latitude dependence [S(λ)] whose origin is widely attributed to a combination of time-varying dipole and non-dipole components. The slope, magnitude and uncertainty of S(λ) are taken as a basis to model the geomagnetic field and understand its evolution. Here we show that variations in S stem from a mathematical aberration of the conversion from directions to poles. A new method to quantify secular variation is proposed.

  15. The Study of a Solar Storm and Its Interplanetary and Geomagnetic Effects

    NASA Astrophysics Data System (ADS)

    Qiu, B. H.; Li, C.

    2015-01-01

    We present a detailed study of a solar storm occurred on 2014 January 7. By using the remote-sensing solar observations from the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO), the eruptions of the solar flare and the coronal mass ejection (CME) are investigated. Based on the particle measurement from the Geostationary Operational Environmental Satellites (GOES) and the in-situ plasma measurement from the Advanced Composition Explorer (ACE), the solar energetic particle (SEP) event, the interplanetary CME (ICME), and its driven shock are analyzed. The influence of the solar storm on the geomagnetic fields is also analyzed. The results show that: (1) The impulsive eruption of the solar flare and the lift of the CME are temporally in accordance with each other. (2) The solar protons are mainly accelerated by the CME-driven shock when the CME travels to 7.7 solar radius, rather than by the magnetic reconnection in the flare. (3) The widths of the interplanetary shock sheath and the ICME itself are derived to be 0.22 AU and 0.26 AU, respectively. (4) The interplanetary shock and the ICME give rise to substorms and aurora, whereas no obvious geomagnetic storm is detected. The reason is that the ICME does not include a structure of the magnetic cloud (MC) or southward magnetic fields.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Global Observations of the O+/H+ Ratio During Large Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Valek, P. W.; Goldstein, J.; Jahn, J. M.; McComas, D. J.; Spence, H. E.

    2014-12-01

    During large geomagnetic storms the fraction of magnetospheric oxygen ions increases compared to hydrogen, and is at times even becomes the dominant population. However, it is not well known how this population is energized and transported in the inner magnetosphere. Using a combination of global images from the Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) mission and in situ observations from the Van Allen Probes Hydrogen Oxygen Proton and Electron (HOPE) sensors, we examine how the inner magnetospheres O+/H+ changes during large storms. TWINS provides continuous global observations of medium energy (<50 keV) H and O Energetic Neutral Atoms (ENAs) from the inner magnetosphere. These ENA observations allow us to follow global changes in the composition and energy during storms. HOPE provides 20 eV-45 keV, high-spatial-resolution, in situ measurements of the inner magnetospheric source populations for the ENAs. We present these complementary (global and local) observations of the O+/H+ ratio for selected case study storms, and examine the dependence on local time and storm phase.

  18. Particle and field characteristics of broadband electrons observed by the FAST satellite during a geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Nakajima, A.; Shiokawa, K.; Seki, K.; Strangeway, R. J.; McFadden, J. P.; Carlson, C. W.

    2007-06-01

    Broadband electrons (BBEs) are remarkable flux enhancements (>1013 eV cm-2 s-1) of precipitating electrons over a broad energy range (0.03-30 keV) near the equatorward edge of the auroral oval during geomagnetic storms. We show characteristics of particles (energy spectra and pitch angle distribution) and fields (electric field, magnetic field, and wave spectra) during a BBE event observed by the Fast Auroral SnapshoT (FAST) satellite. The BBEs were observed at an altitude of ˜2000 km at 59°-61° invariant latitudes (ILATs) and 21 h magnetic local time (MLT). The event was observed at ˜7 min after the onset of a substorm during the main phase of the Bastille Day geomagnetic storm (minimum Dst = -301 nT) on 15 July 2000. The precipitation region of the BBEs corresponded to a localized intensification of auroral emission, lasting ˜14 min, observed by the Polar UVI images at 50°-60° geomagnetic latitudes (MLATs) and 20-21 MLTs. These results suggest that rapid particle acceleration was occurring in the inner magnetosphere associated with a storm-time substorm. The pitch angle distribution of BBEs was isotropic except for a loss cone feature around the field-aligned upward direction at a higher energy range above ˜1 keV, while field-aligned electron fluxes were larger than the perpendicular fluxes below ˜1 keV. These results imply that a higher energy part of the BBEs originated from higher altitudes in the inner magnetosphere and that a lower energy part was accelerated parallel to the local magnetic field at lower altitudes near the satellite. Intense fluctuations of electric and magnetic fields were observed during this BBE event. From these results, we discuss possible acceleration of the lower energy part of BBEs through wave-particle interaction.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes, part 2

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Kane, R. P.; Trivedi, N. B.

    1982-01-01

    Geomagnetic field variations were studied by considering the parameter delta H which indicated H(observed) minus H(model), where H = (X squared + Y squared) (1/2) where X, Y, and Z are the components actually observed. Quiet time base values for 5 deg longitude belts were estimated. After subtracting these from the observed values, the residual delta H (dawn) and delta H (dusk) were studied for the two major storms. It was noticed that the dusk values attained larger (negative) values for a longer time, than the dawn value. Some changes in delta Y and delta Z were also noticed, indicating possibilities of either meridional currents and/or noncoincidence of the central plane of the ring current with the equatorial plane of the Earth. Other details are described.

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

    NASA Astrophysics Data System (ADS)

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

    field and predicting strong 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}=< y, phi_{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

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Relationships Among Geomagnetic Storms, Interplanetary Shocks, Magnetic Clouds, and Sunspot Number During 1995 - 2012

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Chun; Lepping, Ronald P.

    2016-01-01

    During 1995 - 2012, the Wind spacecraft has recorded 168 magnetic clouds (MCs), 197 magnetic cloud-like structures (MCLs), and 358 interplanetary (IP) shocks. Ninety-four MCs and 56 MCLs had upstream shock waves. The following features are found: i) The averages of the solar wind speed, interplanetary magnetic field (IMF), duration (< Δ t >), the minimum of B_{min}, and intensity of the associated geomagnetic storm/activity (Dst_{min}) for MCs with upstream shock waves (MC_{shock}) are higher (or stronger) than those averages for the MCs without upstream shock waves (MC_{no-shock}). ii) The average < Δ t > of MC_{shock} events ({≈} 19.8 h) is 9 % longer than that for MC_{no-shock} events ({≈} 17.6 h). iii) For the MC_{shock} events, the average duration of the sheath (<Δ t_{sheath}>) is 12.1 h. These findings could be very useful for space weather predictions, i.e. IP shocks driven by MCs are expected to arrive at Wind (or at 1 AU) about 12 h ahead of the front of the MCs on average. iv) The occurrence frequency of IP shocks is well associated with sunspot number (SSN). The average intensity of geomagnetic storms measured by < Dst_{min}> for MC_{shock} and MC_{no-shock} events is -102 and -31 nT, respectively. The average values < {Dst}_{min} > are -78, -70, and -35 nT for the 358 IP shocks, 168 MCs, and 197 MCLs, respectively. These results imply that IP shocks, when they occur with MCs/MCLs, must play an important role in the strength of geomagnetic storms. We speculate about the reason for this. Yearly occurrence frequencies of MC_{shock} and IP shocks are well correlated with solar activity ( e.g., SSN). Choosing the correct Dst_{min} estimating formula for predicting the intensity of MC-associated geomagnetic storms is crucial for space weather predictions.

  4. Radial deformation of the solar current sheet as a cause of geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1979-01-01

    It is suggested that the solar current sheet, extending from a coronal streamer, develops a large-scale radial deformation, at times with a very steep gradient at the earth's distance. The associated magnetic field lines (namely, the interplanetary magnetic field (IMF) lines) are expected to have also a large gradient in the vicinity of the current sheet. It is also suggested that some of the major geomagnetic storms occur when the earth is located in the region where IMF field lines have a large dip angle with respect to the ecliptic plane for an extended period (6-48 h), as a result of a steep radial deformation of the current sheet.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Ariyibi, Emmanuel; Joshua, Emanuel; Rabiu, Babatunde

    2013-02-01

    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.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    USGS Publications Warehouse

    Peddie, N.W.

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. Analysis of Changes of Cardiological Parameters at Middle Latitude Region in Relation to Geomagnetic Disturbances and Cosmic Ray Variations

    NASA Astrophysics Data System (ADS)

    Papailiou, M.; Dimitrova, S.; Babayev, E. S.; Mavromichalaki, H.

    2010-01-01

    Collaborating scientific groups from Athens (Greece), Baku (Azerbaijan) and Sofia (Bulgaria) have conducted a research work on the possible effects of geomagnetic field disturbances (GMF) and cosmic ray intensity (CRI) variations on human homeostasis, particularly, the cardio-health state. Electrocardiograms (ECGs) of seven functionally healthy persons were digitally registered at the joint Laboratory of Heliobiology located in the Medical Centre INAM, Baku, on working days and Saturdays. Heart rate values, estimated from ECGs, were analysed in relation to daily values of CRI, as measured by the Neutron Monitor of the University of Athens and daily variations of Dst and Ap geomagnetic indices and some significant results had been revealed in previous studies. Researches were continued by study of additional cardiologic parameters estimated from the same ECG data. In this study digital data of RR interval (the time elapsing between two consecutive R waves in the ECG), namely RRminimum, RRmaximum and RRaverage were analyzed taking into consideration different levels of GMF disturbances (estimated through variations of Dst and Ap indices) and cosmic ray activity (through CRI variations). The data refer to the time period 15 July 2006-31 March 2008. Variations of RR intervals show connection to GMF disturbances and CRI variations. The revealed effects are more pronounced for high levels of geomagnetic activity (when geomagnetic storms occur) and large CRI decreases as well as on the days before and after these variations.

  13. Natural variations in the geomagnetically trapped electron population

    NASA Technical Reports Server (NTRS)

    Vampola, A. L.

    1972-01-01

    Temporal variations in the trapped natural electron flux intensities and energy spectra are discussed and demonstrated using recent satellite data. These data are intended to acquaint the space systems engineer with the types of natural variations that may be encountered during a mission and to augment the models of the electron environment currently being used in space system design and orbit selection. An understanding of the temporal variations which may be encountered should prove helpful. Some of the variations demonstrated here which are not widely known include: (1) addition of very energetic electrons to the outer zone during moderate magnetic storms: (2) addition of energetic electrons to the inner zone during major magnetic storms; (3) inversions in the outer zone electron energy spectrum during the decay phase of a storm injection event and (4) occasional formation of multiple maxima in the flux vs altitude profile of moderately energetic electrons.

  14. The Study on a Solar Storm and Its Interplanetary and Geomagnetic Effects

    NASA Astrophysics Data System (ADS)

    Bai-han, Qiu; Chuan, LI

    2015-10-01

    We present a detailed study on a solar storm occurred on 2014 January 7. By using the remote-sensing observations of solar activities at multiple wavelengths from the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO), the eruptions of the solar flare and coronal mass ejection (CME) are investigated. Based on the measurement of energetic protons from the Geostationary Operational Environmental Satellite (GOES) and the in-situ plasma measurement from the Advanced Composition Explorer (ACE) at the solar-terrestrial L1 point, the solar energetic particle (SEP) event and interplanetary CME (ICME) accompanied by the solar storm, and the shock driven by the ICME are analyzed. The influence of the solar storm on the geomagnetic fields is also analyzed with the ground-based magnetic data. The results in this study show that: (1) The initial time of impulsive phase of the solar flare and the ejection time of the CME are temporally in accordance with each other. (2) The solar protons are mainly accelerated by the CME-driven shock, rather than by the magnetic reconnection in the flare, and the protons are released when the CME travels to 7.7 solar radius. (3) The widths of the interplanetary shock sheath and the ICME itself are derived to be 0.22 AU and 0.26 AU, respectively. (4) The interplanetary shock and the ICME give rise to substorms and aurora, whereas no obvious geomagnetic storm is detected. The reason is that the ICME does not contain a regular structure of magnetic cloud (MC) or evident southward component of magnetic field.

  15. Decay of the Dst field of geomagnetic disturbance after substorm onset and its implication to storm-substorm relation

    NASA Astrophysics Data System (ADS)

    Iyemori, T.; Rao, D. R. K.

    1996-06-01

    In order to investigate the causal relationship between magnetic storms and substorms, variations of the mid-latitude geomagnetic indices, ASY (asymmetric part) and SYM (symmetric part), at substorm onsets are examined. Substorm onsets are defined by three different phenomena; (1) a rapid increase in the mid-latitude asymmetric-disturbance indices, ASY-D and ASY-H, with a shape of so-called `mid-latitude positive bay\\'; (2) a sharp decrease in the AL index; (3) an onset of Pi2 geomagnetic pulsation. The positive bays are selected using eye inspection and a pattern-matching technique. The 1-min-resolution SYM-H index, which is essentially the same as the hourly Dst index except in terms of the time resolution, does not show any statistically significant development after the onset of substorms; it tends to decay after the onset rather than to develop. It is suggested by a simple model calculation that the decay of the magnetospheric tail current after substorm onset is responsible for the decay of the Dst field. The relation between the IMF southward turning and the development of the Dst field is re-examined. The results support the idea that the geomagnetic storms and substorms are independent processes; that is, the ring-current development is not the result of the frequent occurrence of substorms, but that of enhanced convection caused by the large southward IMF. A substorm is the process of energy dissipation in the magnetosphere, and its contribution to the storm-time ring-current formation seems to be negligible. The decay of the Dst field after a substorm onset is explained by a magnetospheric energy theorem. Acknowledgements. This study is supported in part by the Ministry of Education, Science, Sports, and Culture in Japan, under a Grant-in-Aid for Scientific Research (Category B). Topical Editor D. Alcaydé thanks M. Lockwood and N. J. Fox for their help in evaluating this paper.-> Correspondence to: Y. Kamide->

  16. Geomagnetic storm of 29-31 October 2003: Geomagnetically induced currents and their relation to problems in the Swedish high-voltage power transmission system

    NASA Astrophysics Data System (ADS)

    Pulkkinen, Antti; Lindahl, Sture; Viljanen, Ari; Pirjola, Risto

    2005-08-01

    On 30 October 2003, an ongoing geomagnetic superstorm knocked down a part of the high-voltage power transmission system in southern Sweden. The blackout lasted for an hour and left about 50,000 customers without electricity. The incident was probably the most severe geomagnetically induced current (GIC) failure observed since the well-known March 1989 Québec blackout. The "three-phase" storm produced exceptionally large geomagnetic activity at the Fennoscandian auroral region. Although the diversity of the GIC drivers is addressed in the study, the problems in operating the Swedish system during the storm are attributed geophysically to substorms, storm sudden commencement, and enhanced ionospheric convection, all of which created large and complex geoelectric fields capable of driving large GIC. On the basis of the basic twofold nature of the failure-related geoelectric field characteristics, a semideterministic 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. The study revealed that the primary mode of GIC-related failures in the Swedish high-voltage power transmission system were via harmonic distortions produced by GIC combined with too sensitive operation of the protective relays. The outage in Malmö on 30 October 2003 was caused by a combination of an abnormal switching state of the system and tripping of a low-set residual overcurrent relay that had a high sensitivity for the third harmonic of the fundamental frequency.

  17. Radiometric Quantification of Aurora Activities during Severe Geomagnetic Storms from SNPP VIIRS Day-Night Band Observations

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Two severe geomagnetic storms of level G4 occurred so far in 2015. These are among the strongest geomagnetic storms of the current solar cycle (Solar Cycle 24). Both reached G4-Severe level (Kp = 8) on March 17, 2015 and on June 22, 2015, respectively. The March 17 geomagnetic storm is identified as due to the Coronal Mass Ejections (CMEs) which erupted on March 15 from Region 2297 of solar surface. Combined effects of three CMEs produced on June 18, 19 and 21 caused G4-Severe geomagnetic storm on June 22, 2015. During these geomagnetic storms, solar wind interacts with the Earth's magnetic field and causes temporary disturbances of the Earth's magnetosphere and aurora may be seen in low latitude region. The Day Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advancement in night time imaging capabilities. The DNB senses radiance spanning 7 orders of magnitude in one (0.5-0.9 μm) reflective solar band and provides imagery over illumination levels ranging from full sunlight to quarter moon. In this paper, DNB observations of aurora activities during the two geomagnetic storm events are analyzed. During these events, auroras are observed to evolve with salient features by DNB during orbital pass on the night side (~local time 1:30am) in both hemispheres. The radiometricly calibrated DNB observations allow us to quantitatively analyze the large-scale spatial distribution and temporal evolution of aurora during the geomagnetic storms. The radiance data from DNB observation are collected at the night sides of both hemispheres during the two events and geo-located onto geomagnetic local time (MLT) coordinates. Regions of aurora during each orbital pass are identified through image processing by contouring radiance values and excluding regions with stray light near day-night terminator. The evolution of aurora are characterized with time series of the poleward and low latitude boundary of aurora, their

  18. Multiinstrument observations of a geomagnetic storm and its effects on the Arctic ionosphere: A case study of the 19 February 2014 storm

    NASA Astrophysics Data System (ADS)

    Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga; Shume, Esayas B.; Benzon, Hans-Henrik; Mannucci, Anthony J.; Butala, Mark D.; Høeg, Per; Langley, Richard B.

    2017-01-01

    We present a multiinstrumented 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 index that year. The geomagnetic storm was the result of two powerful Earth-directed coronal mass ejections (CMEs). It produced a strong long lasting negative storm phase over Greenland with a dominant energy input in the polar cap. We employed global navigation satellite system (GNSS) networks, geomagnetic observatories, and a specific ionosonde station in Greenland. We complemented the approach with spaceborne measurements in order to map the state and variability of the Arctic ionosphere. In situ observations from the Canadian CASSIOPE (CAScade, Smallsat and IOnospheric Polar Explorer) satellite's ion mass spectrometer were used to derive ion flow data from the polar cap topside ionosphere during the event. Our research specifically found that (1) thermospheric O/N2 measurements demonstrated significantly lower values over the Greenland sector than prior to the storm time. (2) An increased ion flow in the topside ionosphere was observed during the negative storm phase. (3) Negative storm phase was a direct consequence of energy input into the polar cap. (4) Polar patch formation was significantly decreased during the negative storm phase. This paper addresses the physical processes that can be responsible for this ionospheric storm development in the northern high latitudes. We conclude that ionospheric heating due to the CME's energy input caused changes in the polar atmosphere resulting in Ne upwelling, which was the major factor in high-latitude ionosphere dynamics for this storm.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Toward a standardized definition of geomagnetic sudden impulses and storm sudden commencements

    NASA Astrophysics Data System (ADS)

    Kamide, Y.; Joselyn, J. A.

    In an attempt to resolve some ambiguity in defining geomagnetic sudden impulses (Sis) and storm sudden commencements (SSCs) using the existing phenomenological definition (see, for example, Mayaud and Romana [1977]; Mayaud [1980]), Joselyn and Tsurutani [1990] recently constructed a scheme in which SSCs are a subset of Sis, depending on the magnitude of subsequent geomagnetic activity. For quantitative application, they have proposed that an SI be specified as a sharp change (at least 10 nT in 3 minutes or less) observed nearly simultaneously (within a few minutes) in either component of the horizontal magnetic field at globally spaced observatories near 20° geomagnetic latitude. In addition, SSCs are those Sis followed within 24 hours by an hourly Dst index of at least -50 nT. Because the Dst index is not readily available, the recommended provisional alternative indicators are a 3-hourly Kp index of 5 or more and a half-daily a a index of 60 or more. Joselyn and Tsurutani [1990] have recommended these new quantitative definitions of the two terms (Sis and SSCs) for open discussion.

  1. Energetic Electron Transport in the Inner Magnetosphere During Geomagnetic Storms and Substorms

    NASA Technical Reports Server (NTRS)

    McKenzie, D. L.; Anderson, P. C.

    2005-01-01

    We propose to examine the relationship of geomagnetic storms and substorms and the transport of energetic particles in the inner magnetosphere using measurements of the auroral X-ray emissions by PIXIE. PIXIE provides a global view of the auroral oval for the extended periods of time required to study stormtime phenomena. Its unique energy response and global view allow separation of stormtime particle transport driven by strong magnetospheric electric fields from substorm particle transport driven by magnetic-field dipolarization and subsequent particle injection. The relative importance of substorms in releasing stored magnetospheric energy during storms and injecting particles into the inner magnetosphere and the ring current is currently hotly debated. The distribution of particles in the inner magnetosphere is often inferred from measurements of the precipitating auroral particles. Thus, the global distributions of the characteristics of energetic precipitating particles during storms and substorms are extremely important inputs to any description or model of the geospace environment and the Sun-Earth connection. We propose to use PIXIE observations and modeling of the transport of energetic electrons to examine the relationship between storms and substorms.

  2. Evolution of the Aurora during the Great Geomagnetic Storm of 1859

    NASA Astrophysics Data System (ADS)

    Green, J. L.; Boardsen, S. A.

    2004-12-01

    The great geomagnetic storm of 1859 extended over a period from August 28 through to September 3 and was, arguably, the first space weather event of the modern age. The storm clearly demonstrated that the sun and aurora were connected and that auroras generated strong currents. A significant portion of the world's 140,000 miles of telegaph lines were adversely effected, many of which were unusable for a number of hours. In addition to the scientific measurements that where published, primarily in the American Journal of Science, newspapers of that era provided an untapped wealth of first hand observations giving time and location along with reports of the auroral forms and colors. Low latitude auroral events where big news for both small local and metropolitan newspapers. If the weather was clear during an auroral display, you could almost guarantee a story in the local news the next day or even a few days later. The evolution of the aurora over the great storm period will be shown and is accomplished by combining the observations from many available sources (ie: scientific observations, newspaper accounts, ship logs, and national weather services reports) in two-hour intervals. At its height, the aurora was described as a blood or deep crimson red that was so bright that one could read a newspaper by. The precipitation extended over L shells from 4 to 1.3. The implications of the configuration of the magnetosphere during the great storm will also be discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Curtis, B.

    2015-12-01

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

  5. Relevance vector machines as a tool for forecasting geomagnetic storms during years 1996-2007

    NASA Astrophysics Data System (ADS)

    Andriyas, T.; Andriyas, S.

    2015-04-01

    In this paper, we investigate the use of relevance vector machine (RVM) as a learning tool in order to generate 1-h (one hour) ahead forecasts for geomagnetic storms driven by the interaction of the solar wind with the Earth's magnetosphere during the years 1996-2007. This epoch included solar cycle 23 with storms that were both ICME (interplanetary coronal mass ejection) and CIR (corotating interaction region) driven. Merged plasma and magnetic field measurements of the solar wind from the Advanced Composition Explorer (ACE) and WIND satellites located upstream of the Earth's magnetosphere at 1-h cadence were used as inputs to the model. The magnetospheric response to the solar wind driving measured by the disturbance storm time or the Dst index (measured in nT) was used as the output to be forecasted. The model was first tested on previously reported storms in Wu and Lundstedt (1997) and it gave a linear correlation coefficient, ρ, of above 90% and prediction efficiency (PE) above 80%. During 1996-2007, several storms (within each year) were chosen as test cases to analyze the forecasting robustness of the model. The top three forecasts per year were analyzed to assess the generalization ability of the model. These included storms with varying intensities ranging from weak (-53.01 nT) to strong (-422.02 nT) and durations (119-445 h). The top RVM forecast in a given year had ρ above 85% (87.00-96.85%), PE > 73 % (73.59-93.59%), and a root mean square error (RMSE) ranging from 9.31 to 33.45 nT. A qualitative comparison is made with model forecasts previously reported by Ji et al. (2012). We found that the robustness of the model with regards to fast learning and generating forecasts within acceptable error bounds makes it a very good proposition as a prediction tool (given the solar wind parameters) for space weather monitoring.

  6. Geomagnetic Secular Variation Prediction with Thermal Heterogeneous Boundary Conditions

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Solar daily variation at geomagnetic observatories in Pakistan

    NASA Astrophysics Data System (ADS)

    Rahim, Zain; Kumbher, Abdul Salam

    2016-03-01

    A study of solar daily variation is performed using the famous Chapman-Miller method for solar cycles 22 & 23 (1986-2007). The objective is to study the characteristics of Sq variation at Pakistani geomagnetic observatories using solar harmonics and a more traditional five quietest day's method. The data recorded at the Karachi geomagnetic observatory for SC 22 and 23 and data sets from other Pakistani geomagnetic observatories; Sonmiani, Quetta and Islamabad are analyzed for H, D and Z components of the geomagnetic field. Except for the D and Z components at Karachi and Sonmiani and H component at Islamabad, the two solar daily variations correlated well with each other. Also, the synthesized daily variation from the solar harmonics of H, D and Z components explained the equivalent Sq current system reasonably well for all seasons. For H component, the first solar harmonic (s1) obtained from spherical harmonic analysis of the data, appeared as the largest harmonic with no significant changes for the seasonal division of data. However, for D and Z components, amplitudes are comparable, but undergo distinct variations. s1 for H and D components increases with magnetic activity while for Z component it is the largest for the medium phase of magnetic activity. With the sunspot number division of data, the weighted mean of the Wolf ratio of all three components is in good agreement with the previous studies. The synthesized solar daily variation for D component, S(D), at Karachi, Sonmiani, Quetta and Islamabad did not show any signs of winter anomaly for the period studied. However, S(D) variation at Karachi during winter season showed morning minimum followed by a maximum at local noon and another minimum in the afternoon. We suggest this could be the effects of Equatorial Ionospheric Anomaly (EIA) observable at the Karachi observatory only during the winter season. Similarly, much disturbed in equinoctial and summer months, S(Z) illustrated an unwavering daily

  9. Prompt penetration electric fields and the extreme topside ionospheric response to the June 22-23, 2015 geomagnetic storm as seen by the Swarm constellation

    NASA Astrophysics Data System (ADS)

    Astafyeva, Elvira; Zakharenkova, Irina; Alken, Patrick

    2016-09-01

    Using data from the three Swarm satellites, we study the ionospheric response to the intense geomagnetic storm of June 22-23, 2015. With the minimum SYM-H excursion of -207 nT, this storm is so far the second strongest geomagnetic storm in the current 24th solar cycle. A specific configuration of the Swarm satellites allowed investigation of the evolution of the storm-time ionospheric alterations on the day- and the nightside quasi-simultaneously. With the development of the main phase of the storm, a significant dayside increase of the vertical total electron content (VTEC) and electron density Ne was first observed at low latitudes on the dayside. From ~22 UT of 22 June to ~1 UT of 23 June, the dayside experienced a strong negative ionospheric storm, while on the nightside an extreme enhancement of the topside VTEC occurred at mid-latitudes of the northern hemisphere. Our analysis of the equatorial electrojet variations obtained from the magnetic Swarm data indicates that the storm-time penetration electric fields were, most likely, the main driver of the observed ionospheric effects at the initial phase of the storm and at the beginning of the main phase. The dayside ionosphere first responded to the occurrence of the strong eastward equatorial electric fields. Further, penetration of westward electric fields led to gradual but strong decrease of the plasma density on the dayside in the topside ionosphere. At this stage, the disturbance dynamo could have contributed as well. On the nightside, the observed extreme enhancement of the Ne and VTEC in the northern hemisphere (i.e., the summer hemisphere) in the topside ionosphere was most likely due to the combination of the prompt penetration electric fields, disturbance dynamo and the storm-time thermospheric circulation. From ~2.8 UT, the ionospheric measurements from the three Swarm satellites detected the beginning of the second positive storm on the dayside, which was not clearly associated with electrojet

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

    NASA Astrophysics Data System (ADS)

    Mungufeni, Patrick

    2016-07-01

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

  11. Plasmaspheric Depletion and Refilling after Geomagnetic Storms in the Dynamic Model of the Plasmasphere

    NASA Astrophysics Data System (ADS)

    Moschou, S. P.; Pierrard, V.; Lemaire, J. F.

    2015-12-01

    The three-dimensional physical dynamic kinetic model of the plasmasphere is a physics-based model partially constrained by empirical observations and available for running on the space weather portal. The position of the plasmapause is determined by the interchange instability mechanism. The level of geomagnetic activity driven by the Kp index determines the convection electric field which dominates at large radial distances. During storm and substorm events, the convection rate increases, especially in the postmidnight MLT sector. This leads to an inward motion of the plasmapause in this MLT sector during the storms and a depletion of the outer flux tubes. The combination with the corotation electric field leads later to the formation of a plume in the afternoon sector which then rotates with the Earth. After geomagnetic storms, progressive refilling process takes several days to increase the density in the depleted flux tubes located in regions between the vestigial plasmapause and the new plasmapause situated at larger radial distance. The model is coupled with an empirical model of the ionosphere which determines the boundary conditions at low altitudes. Like in other kinetic models of planetary and stellar atmospheres, the density, flux, velocity and temperatures of the particles are obtained by solving the kinetic evolution equation to determine the velocity distribution function of the particles. Additional new results are related to the consideration of the plasmaspheric wind appearing during low activity periods. Comparisons with IMAGE and CLUSTER observations show good agreement with the results of the model, including during periods when a plume is visible during several successive days.

  12. Localized sudden changes in the geomagnetic secular variation.

    USGS Publications Warehouse

    Alldredge, L.R.

    1987-01-01

    There is much debate as to whether there was a worldwide geomagnetic jerk in 1969 or 1970. It is agreed that there was an unusual sharp change in the secular variation in the east component, Y, in Europe at that time. This note points out how a localized sudden change in the secular variation pattern of one component in Europe can occur without having any large worldwide effects in any of the components. The accompanying changes in the spherical harmonic coefficients for such a localized change are also discussed. -after Author

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

    NASA Astrophysics Data System (ADS)

    Dashora, N.; Sharma, S.; Dabas, R. S.; Alex, S.; Pandey, R.

    2009-05-01

    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) enhanced background level of VTEC as compared to the mean

  14. High-frequency ``Pc1'' during the geomagnetic storm of November 2004

    NASA Astrophysics Data System (ADS)

    Ermakova, Elena; Demekhov, Andrei; Yahnin, Alexander; Kotik, Dmitry; Yahnina, Tatyana

    At 00-04 UT on 10 November 2004 during a strong geomagnetic storm the IMAGE spacecraft observed proton auroras at extremely low latitudes (L=2.4). Conjugated with the auroras the low orbiting NOAA satellites detected localized precipitation of energetic (>30 keV) protons (LPEP). The LPEP are typically associated with EMIC waves or geomagnetic pulsations in the Pc1 range. This means that both EMIC waves and LPEP are the result of ion-cyclotron interaction operating in the equatorial plane in the magnetosphere. Close to the meridian of the low-latitude proton aurora there exist several geomagnetic observatories located at L>3.4, but none of them detected any pulsations in the Pc1 range. Here we present results of observations performed at a mid-latitude site Novaya Zhizn located at L=2.6, that is, close to the observed proton aurora. This site is equipped with a magnetometer which produces pulsation spectra up to 30 Hz. Not surprisingly, we found some emissions correlated with the proton aurora and LPEP at frequencies exceeding first Sсhumann resonance. Oscillations of the horizontal component of the magnetic field were detected at frequencies of about 9.5-11.5 Hz. It worth noting that both modeling and IMAGE EUV and RPI observations show that the plasmasphere was very contracted during the storm and the plasmapause was located at about L=2.5. The precipitation zone was projected onto the plasmapause. The emission frequency corresponds to the band above the equatorial gyrofrequency of He+ ions at the geomagnetic flux tube of the precipitation region and, thus, the signal may be associated with the ion-cyclotron instability of electromagnetic ion-cyclotron (EMIC) waves at the unusually low latitude plasmapause. Further study has revealed three more periods of the detection of such "high frequency" emissions: from 22:30 UT on November 10, 2004 to 03:00 UT on November 11, 2004,from 06-08 UT on November 11, 2004, and 09-12 UT on November 11, 2004. During the period 06

  15. Seasonal variations of storm zones on Mars

    NASA Astrophysics Data System (ADS)

    Hollingsworth, J. L.; Haberle, R. M.; Schaeffer, J.

    1997-05-01

    Using the NASA Ames Mars general circulation model, an annual cycle simulation has been performed corresponding to a low atmospheric dust loading. Surface pressure time series near the Viking Lander 2 location have been analyzed using singular spectrum analysis (SSA) and autoregressive models to isolate statistically significant spectral power. Also, circulation statistics have been separated using band-pass time filtering and analyzed for coherent spatial patterns. During northern autumn, winter and spring seasons, localized `storm zones' can occur which are particularly strong within the lowlands of Arcadia, Acidalia and Utopia. During early northern spring, the transient eddy activity is stronger than that found during any other season. With weakening baroclinicity accompanying seasonal transition toward midspring, the eddies become less vigorous and the associated storm `belt' shifts into higher latitudes. Since transient baroclinic eddies are active agents in the transport of heat, momentum and moisture in middle latitudes, variations in the storm zones during the seasonal cycle will have important implications for Mars' regional climate.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  17. Long-lasting negative ionospheric storm effects in low and middle latitudes during the recovery phase of the 17 March 2013 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Yue, Xinan; Wang, Wenbin; Lei, Jiuhou; Burns, Alan; Zhang, Yongliang; Wan, Weixing; Liu, Libo; Hu, Lianhuan; Zhao, Biqiang; Schreiner, William S.

    2016-09-01

    In this paper, an ionospheric electron density reanalysis algorithm was used to generate global optimized electron density during the 17-18 March 2013 geomagnetic storm by assimilating 10 low Earth orbit satellites based and 450 ground global navigation satellite system receiver-based total electron content into a background ionospheric model. The reanalyzed electron density could identify the large-scale ionospheric features quite well during storm time, including the storm-enhanced density, the positive ionospheric storm effect during the initial and main phases, and the negative ionospheric storm effect during the recovery phase. The simulations from the Thermosphere Ionosphere Electrodynamics General Circulation Model can reproduce similar large-scale ionospheric disturbances as seen in the reanalysis results. Both the reanalysis and simulations show long-lasting (>17 h) daytime negative storm effect over the Asia sector as well as hemispheric asymmetry during the recovery phase. Detailed analysis of the Global Ultraviolet Imager-derived O/N2 ratio and model simulations indicate that the polar ward meridional wind disturbance, the downward E × B drift disturbance and O/N2 depletion might be responsible for the negative storm effect. The hemispheric asymmetry is mainly caused by the geomagnetic field line configuration, which could cause hemispheric asymmetry in the O/N2 depletion.

  18. Studying Peculiarities of Ionospheric Response to the 2015 March 17-19 Geomagnetic Storm in East Asia: Observations and Simulation

    NASA Astrophysics Data System (ADS)

    Romanova, Elena; Zherebtsov, Gelii; Polekh, Nelya; Wang, Xiao; Wang, Guojun; Zolotukhina, Nina; Shi, Jiankui

    2016-07-01

    We report results of the research into effects of the strong geomagnetic storm in the ionosphere of high, middle, and low latitudes on March 17-19, 2015. The research relies on measurements made at the network of ionospheric stations located near the 120°E meridian. The analysis of experimental data has revealed that at the beginning of the main storm phase the equatorial wall of the main ionospheric trough (MIT) shifted towards geographic latitudes 58-60°N, which caused negative disturbances in subauroral latitudes and positive disturbances in middle latitudes. Further displacement of the MIT equatorial wall towards a geographic latitude of 52° N led to a decrease in the F2-layer critical frequency (foF2) up to 2 MHz in middle latitudes during evening and night hours, and to the appearance of sporadic layers in these latitudes due to energetic particle precipitation. Such phenomena are largely specific to the subauroral ionosphere. During the recovery storm phase on March 18, 2015 during daylight hours, negative disturbances were recorded at all the stations. Since prolonged negative disturbances are usually associated with a reduction in the ratio of concentrations of atomic oxygen and molecular nitrogen [O]/[N2] which is transported by disturbed thermospheric wind from auroral latitudes to middle and low ones, we analyzed measurements of [O]/[N2], made by GUVI (Global Ultraviolet Imager, http://guvi.jhuapl.edu/site/gallery/guvi-galleryl3on2.shtml), during this storm. The storm appeared to be characterized by very low values of [O]/[N2] which were recorded in the longitude sector 60 - 150°E up to 15°N on March 18. The discovered peculiarities of the ionospheric response to the storm were interpreted using a theoretical model of ionosphere-plasmosphere coupling developed at ISTP SB RAS. The simulation showed that the displacement of MIT equatorial wall resulted in foF2 variations similar to those observed during the main storm phase in subauroral and middle

  19. Nonlinearity in Chorus Waves During a Geomagnetic Storm on 1 November 2012

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Paulson, K. W.; Torbert, R. B.; Spence, H.; Kletzing, C.; Kurth, W. S.; Skoug, R. M.; Larsen, B.

    2013-12-01

    In this study, we investigate possibility of nonlinearity in chorus waves during a geomagnetic storm on 1 November 2012. The data we use are measured by the Van Allen Probes B (RBSP-B). Wave data from the EMFISIS instrument and particle data from the ECT instrument are analyzed. HOPE instrument on ECT provides measurements of plasmasheet electrons. Chorus waves are frequently measured in the morning side during the main phase of this storm. During this storm interval, large amplitude chorus waves are seen with amplitudes of the order of ~0.6 nT and >7 mV/m, which is similar to or larger than the size of ULF waves. The waves quite often consist of rising tones during the burst sampling. Since the rising tone is known as a signature of nonlinearity, the large portion of the waves are considered as nonlinear at least during the burst sampling. These results underline the importance of nonlinearity in the dynamics of chorus waves. We further examine the consistency between the measurement and the nonlinear theory. For example, the relation between wave amplitudes and frequency drift rate is checked.

  20. Marine Magnetic Anomalies, Oceanic Crust Magnetization, and Geomagnetic Time Variations

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Arkani-Hamed, J.

    2005-12-01

    Since the classic paper of Vine and Matthews (Nature, 1963), marine magnetic anomalies are commonly used to date the ocean floor through comparison with the geomagnetic polarity time scale and proper identification of reversal sequences. As a consequence, the classical model of rectangular prisms bearing a normal / reversed magnetization has been dominant in the literature for more than 40 years. Although the model explains major characteristics of the sea-surface magnetic anomalies, it is contradicted by (1) recent advances on the geophysical and petrologic structure of the slow-spreading oceanic crust, and (2) the observation of short-term geomagnetic time variations, both of which are more complex than assumed in the classical model. Marine magnetic anomalies may also provide information on the magnetization of the oceanic crust as well as short-term temporal fluctuations of the geomagnetic field. The "anomalous skewness", a residual phase once the anomalies have been reduced to the pole, has been interpreted either in terms of geomagnetic field variations or crustal structure. The spreading-rate dependence of anomalous skewness rules out the geomagnetic hypothesis and supports a spreading-rate dependent magnetic structure of the oceanic crust, with a basaltic layer accounting for most of the anomalies at fast spreading rates and an increasing contribution of the deeper layers with decreasing spreading rate. The slow cooling of the lower crust and uppermost mantle and serpentinization, a low temperature alteration process which produces magnetite, are the likely cause of this contribution, also required to account for satellite magnetic anomalies over oceanic areas. Moreover, the "hook shape" of some sea-surface anomalies favors a time lag in the magnetization acquisition processes between upper and lower magnetic layers: extrusive basalt acquires a thermoremanent magnetization as soon as emplaced, whereas the underlying peridotite and olivine gabbro cool slowly

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    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 < -200 nT) of solar cycle 24 occurred on "St. Patrick's day" (17 March 2015). Notably, it was a two-step storm. The source of the storm can be traced back to the solar event on 15 March 2015. At ~2:10 UT on that day, SOHO/LASCO C3 recorded a partial halo coronal mass ejection (CME), which was associated with a C9.1/1F flare (S22W25) and a series of type II/IV 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. Geomagnetic secular variation timescales under rapid rotation constraints

    NASA Astrophysics Data System (ADS)

    Coutelier, Maélie; Amit, Hagay; Christensen, Uli

    2016-04-01

    Based on geomagnetic observations, numerical dynamo simulations and frozen-flux theory it has been argued that the secular variation (SV) timescale of the magnetic field varies as 1l (where l is the spherical harmonic degree), except for the dipole. The equatorial symmetry of the core flow, which is expected due to rapid rotation effects, allows SV timescale decomposition into symmetric and asymmetric parts. We show in geomagnetic field models and in numerical dynamo simulations that the 1/l scaling law applies for the symmetric and asymmetric timescales as well separately. In both observed and simulated data the symmetric/asymmetric SV timescales are smaller/larger respectively, than in that of the full dataset. The symmetric dipole time scale is well fitted by the 1/l law in the geomagnetic field models, but not in the dynamo models. The opposite holds for the symmetric quadrupole time scales. Assuming that the dynamo models are more representative of the long-term behavior than the geomagnetic field models due to the much longer averaging time of the former, this may suggest that during the historical era the symmetric dipole SV timescale was exceptionally large and the symmetric quadrupole SV timescale was exceptionally small. Since present-day symmetric dipole SV timescale is below the 1/l fit, this may further suggest that the nearly constant dipole tilt between 1840-1960 was anomalous. Failure to explain the dipole SV timescales (both axial and equatorial) by the scaling law may suggest strong diffusion effects for the lowest degrees. Overall, our analytical fits for the symmetric and asymmetric SV timescales provide new insight into the re-organization times of different length scales in Earth's outer core.

  4. A study on the response of the Equatorial Ionization Anomaly over the East Africa sector during the geomagnetic storm of November 13, 2012

    NASA Astrophysics Data System (ADS)

    Joseph, Olwendo Ouko; Yamazak, Yosuke; Cilliers, Pierre; Baki, Paul; Ngwira, Chigomezyo M.; Mito, Collins

    2015-06-01

    Using a set of up to 12 International GNSS Services (IGS) receivers around the East African region, we present the formation of the peak of ionospheric Equatorial Ionization Anomaly during the geomagnetic storm of 13th November 2012. The diurnal pattern of total electron content (TEC) shows a strong negative storm during the main phase of the storm. Latitudinal variation of TEC shows development of strong Equatorial Ionization Anomaly (EIA) on the recovery phase. Evidence in terms of magnetic variations during the storm period, indicates that the penetration of interplanetary electric fields is the main cause of the negative ionospheric effect during the main phase of the storm. Observation shows the occurrence of very strong westward electric fields arising from the IMF Bz turning southward a few hours after sunset local time. TEC enhancement during the recovery phase on the 16th are attributed to the increased ionospheric disturbance dynamo electric fields. In addition the EIA crest was found to intensify in amplitude as well as expand in latitudinal extent.

  5. Contribution of the topside and bottomside ionosphere to the total electron content during two strong geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Zhu, Qingyu; Lei, Jiuhou; Luan, Xiaoli; Dou, Xiankang

    2016-03-01

    In this study, the ionospheric observations from ionosondes, GPS receivers, and incoherent scatter radars (ISR) at low and middle latitudes were used to investigate the contribution of the bottomside and topside ionosphere to the total electron content (TEC) during the September 2005 and December 2006 geomagnetic storms. It was found that the contribution of the bottomside TEC below F2 peak (BTEC) to the ionosonde ionospheric TEC (ionosonde ITEC), namely, BTEC/ITEC was almost constant during both quiet and storm times, while the ratio of BTEC to GPS TEC (i.e., BTEC/GPS-TEC) underwent obvious diurnal variations at all stations. The BTEC/GPS-TEC during the positive phase was similar to that during quiet time, regardless of the formation mechanisms of the observed positive phases. Moreover, our analysis revealed that the ISR calculated BTEC/ITEC during positive ionospheric phases was comparable to that during quiet time. This suggests that the positive phases in these two events mainly occurred around the F2 peak height. There were large differences between the calculated BTEC/ITEC from the ISR observations and BTEC/GPS-TEC during the negative phase or at night when the plasmasphere possibly contributed significantly to the TEC in the relative sense. Although the absolute changes of the topside TEC were larger than the bottomside TEC at low and middle latitudes associated with the larger topside effective ionospheric thickness, unlike the October 2003 superstorms, the relative changes of the topside TEC to the quiet time reference in these two strong storms were not greater than the changes of the bottomside TEC and peak density NmF2.

  6. Isis 1 observations of the high-latitude ionosphere during a geomagnetic storm.

    NASA Technical Reports Server (NTRS)

    Whitteker, J. H.; Hartz, T. R.; Brace, L. H.; Burrows, J. R.; Heikkila, W. J.; Sagalyn, R. C.; Thomas, D. M.

    1972-01-01

    The Isis 1 satellite has made measurements of several ionospheric and related parameters, and the results of the various measurements have been compared in detail for two north transpolar passes during the geomagnetic storm of February 3, 1969. Simultaneous measurements were made of local electron and ion densities and temperatures, electron density between the satellite and the peak of the F layer, radio noise, and particle fluxes over a wide energy range extending down to 10 eV. Several features of the ionosphere (in particular, enhancements of radio noise, scale height, and plasma temperatures) appear to be due to soft-particle (100 eV to 1 keV) precipitation, which is related to magnetospheric structure as delineated by the observation of more energetic particles. The magnetosheath particles precipitating on the dayside of the polar cap are particularly effective.

  7. GPS observation of continent-size traveling TEC pulsations at the start of geomagnetic storms

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    We report our experimental observation of continent-size traveling plasma disturbances using GPS measurements of total electron content (TEC) over the North American sector. These plasma disturbances occurred at the beginning of geomagnetic storms, immediately after the shock arrived, and prior to the appearance of large-scale traveling ionospheric disturbances (LSTIDs) from the auroral region. Specifically, these supersize TEC perturbations were observed when the interplanetary magnetic field Bz was oscillating between northward and southward directions. They were found to propagate zonally with a propagation speed of 2-3 km/s. We interpret these TEC pulsations as ion drift waves in the magnetosphere/plasmasphere that propagate azimuthally inside the GPS orbit.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  9. Radiation belt electron reanalysis over two solar cycles: Comparitive modeling and analysis of several geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Kellerman, Adam; Turner, Drew; Kondrashov, Dmitri; Shprits, Yuri; Podladchikova, Tatiana; Drozdov, Alexander

    Earth’s electron radiation belts are a dynamic system, coupled to the solar wind and to the ionosphere. Understanding the observed dynamics requires consideration of the coupling between the three systems. Remote sensing and in situ observations provide information on the current state of the radiation belt system, and together with careful modeling may be used to resolve the physical processes at work. The Versatile Electron Radiation Belt (VERB) model solves the Fokker-Planck diffusion equation in three dimensional invariant coordinates, which allows one to more effectively separate adiabatic and non-adiabatic changes in the radiation belt electron population. The model includes geomagnetic storm intensity dependent parameterizations of the following dominant magnetospheric waves: day- and night-side chorus, plasmaspheric hiss (in the inner magnetosphere and inside the plume region), lightning and anthropogenic generated waves, and electro-magnetic ion cyclotron (EMIC) waves, also inside of plasmaspheric plumes. The model is used to forecast the future state of the radiation belt electron population, while real-time data may be used to update the current state of the belts through assimilation with the model. The Kalman filter provides a computationally inexpensive method to assimilate data with a model, while taking into account the errors associated with each. A split-operator Kalman filter approach is applied in this study, which provides a fast and effective way to assimilate data over very long time periods. Data error estimates are derived through the intercalibration, while model error estimates are adjusted dynamically based on the model forecast performance. In the current study, a set of geomagnetic storms are investigated comparatively using solar wind data, and reanalysis of electron phase space density from several different spacecraft missions. The storms occurred during periods that span over two solar cycles, and include CME and CIR driven

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Modeling of Coronal Mass Ejections that Caused Particularly Large Geomagnetic Storms Using ENLIL Heliosphere Cone Model

    NASA Technical Reports Server (NTRS)

    Taktakishvili, A.; Pulkkinen, A.; MacNeice, P.; Kuznetsova, M.; Hesse, M.; Odstrcil, D.

    2011-01-01

    In our previous paper we reported the results of modeling of 14 selected well -observed strong halo coronal mass ejection (CME) events using the WSA -ENLIL cone model combination. Cone model input parameters were obtained from white light coronagraph images of the CME events using the analytical method developed by Xie et al. This work verified that coronagraph input gives reasonably good results for the CME arrival time prediction. In contrast to Taktakishvili et al., where we started the analysis by looking for clear CME signatures in the data and then proceeded to model the interplanetary consequences at 1 AU, in the present paper we start by generating a list of observed geomagnetic storm events and then work our way back to remote solar observations and carry out the corresponding CME modeling. The approach used in this study is addressing space weather forecasting and operational needs. We analyzed 36 particularly strong geomagnetic storms, then tried to associate them with particular CMEs using SOHO/LASCO catalogue, and finally modeled these CMEs using WSA-ENLIL cone model. Recently, Pulkkinen et al. developed a novel method for automatic determination of cone model parameters. We employed both analytical and automatic methods to determine cone model input parameters. We examined the CME arrival times and magnitude of impact at 1 AU for both techniques. The results of the simulations are compared with the ACE satellite observations. This comparison demonstrated that WSA -ENLIL model combination with coronagraph input gives reasonably good results for the CME arrival times for this set of 'geoeffective" CME events as well.

  12. The Evolution of Ring Current Energy Density and Energy Content during Geomagnetic Storms Based on Van Allen Probes Measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Freidel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.; Rodriguez, J. V.

    2015-12-01

    Enabled by the comprehensive measurements from the MagEIS, HOPE, and RBSPICE instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of particles with different energies and species to the ring current energy density and their dependence on the geomagnetic storms and storm phases are quantified. During the main phases of moderate storms (with minimum Dst between -50 nT and -100 nT), ions of energies < 50 keV and electrons of energies of <35 keV contribute more significantly to the ring current energy than those of higher energies. During the recovery phase and quiet times higher energy protons dominate the ring current energy content. For the March 29, 2013 moderate storm, the contribution from O+ is ~25% of the ring current energy content during the main phase, and the majority of that comes from < 50 keV O+. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions and low energy O+ plays an important role in ring current dynamics. The contribution of electrons to the ring current energy content is up to ~7% during this moderate storm and the magnetic local time dependence of electron energy density is also investigated. However, the ring current energy partitions for different species and energy ranges are very different during the great storm of 17 March 2015 (with minimum Dst<-210 nT).

  13. Two-scale model of a geomagnetic field variation

    NASA Technical Reports Server (NTRS)

    Braginsky, S. I.; Le Mouel, J. L.

    1993-01-01

    The effect of the vertical scale is investigated by considering a simple kinematic two-scale model of fluid flow inducing a variable magnetic field. Depending on the time constant, the induced magnetic field displays a variety of behaviors and geometries. In the high-frequency case, for example, a strong magnetic field tangential to the core mantle boundary, and hidden in the Delta layer, can be generated. A detailed computation and description of this magnetic field are presented. Some possible features of the secular variation of the actual geomagnetic field are discussed in the light of the model proposed here.

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

    NASA Astrophysics Data System (ADS)

    Sharma, A. K.; et al.

    2006-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  17. Support Vector Machine combined with Distance Correlation learning for Dst forecasting during intense geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Lu, J. Y.; Peng, Y. X.; Wang, M.; Gu, S. J.; Zhao, M. X.

    2016-01-01

    In this study we apply the Support Vector Machine (SVM) combined together with Distance Correlation (DC) to the forecasting of Dst index by using 80 intense geomagnetic storms (Dst ≤ - 100 nT) from 1995 to 2014. We also train the Neural Network (NN) and the Linear Machine (LM) to verify the effectiveness of SVM. The purpose for us to introduce DC is to make feature screening in input datasets that can effectively improve the forecasting performance of the SVM. For comparison, we estimate the correlation coefficients (CC), the RMS errors, the absolute value of difference in minimum Dst (ΔDstmin) and the absolute value of difference in minimum time (ΔtDst) between observed Dst and predicted one. K-fold Cross Validation is used to improve the reliability of the results. It is shown that DC-SVM model exhibits the best forecasting performance for all parameters when all 80 events are considered. The CC, the RMS error, the ΔDstmin, and the ΔtDst of DC-SVM are 0.95, 16.8 nT, 9.7 nT and 1.7 h, respectively. For further comparison, we divide the 80 storm events into two groups depending on minimum value of Dst. It is also found that the DC-SVM is better than other models in the two groups.

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

    PubMed Central

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

    PubMed

    Olson, P

    2007-12-18

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

  20. Ionospheric E-Region Response to Solar-Geomagnetic Storms Observed by TIMED/SABER and Application to IRI Storm-Model Development

    NASA Technical Reports Server (NTRS)

    Mertens, Christopher J.; Mast, Jeffrey C.; Winick, Jeremy R.; Russell, James M., III; Mlynczak, Martin G.; Evans, David S.

    2007-01-01

    The large thermospheric infrared radiance enhancements observed from the TIMED/SABER experiment during recent solar storms provide an exciting opportunity to study the influence of solar-geomagnetic disturbances on the upper atmosphere and ionosphere. In particular, nighttime enhancements of 4.3 um emission, due to vibrational excitation and radiative emission by NO+, provide an excellent proxy to study and analyze the response of the ionospheric E-region to auroral electron dosing and storm-time enhancements to the E-region electron density. In this paper we give a status report of on-going work on model and data analysis methodologies of deriving NO+ 4.3 um volume emission rates, a proxy for the storm-time E-region response, and the approach for deriving an empirical storm-time correction to International Reference Ionosphere (IRI) E-region NO+ and electron densities.

  1. Long Term Geomagnetic Variations and Whole-Mantle Convection Processes

    NASA Astrophysics Data System (ADS)

    Biggin, A. J.; Steinberger, B. M.; Aubert, J.; Suttie, N.; Holme, R.; Torsvik, T. H.; van der Meer, D.; Van Hinsbergen, D. J.

    2012-12-01

    It has long been suspected that palaeomagnetically-observed variations in geomagnetic behaviour occurring over tens to hundreds of millions of years result from changes in core-mantle boundary (CMB) heat flow, itself controlled by lower mantle dynamics. Furthermore, the last few decades have seen numerous claims of causal relations between the palaeomagnetic record and surface events inferred from the geological record that invoke whole-mantle convection processes (sinking slabs, rising plumes, and true polar wander). Recent findings in seismology, geodynamics, and the numerical simulation of both mantle convection and the geodynamo do provide qualitative support for such ideas. CMB heat flow is probably highly heterogeneous and susceptible to substantial changes through variations in locations and rates of subduction, plume flux, or simply by rotations of the entire pattern with respect to the geodynamo via true polar wander (TPW). Numerical geodynamo modelling suggests that long term geomagnetic behaviour is sensitive to changes in total heat flow and its spatial pattern but cannot yet quantitatively confirm that the variations we expect to see in CMB heat flow over tens to hundreds of Myr (up to several tens of percent) are sufficient to modify the behaviour as observed. The most dramatic change in long-term geomagnetic behaviour observed in the last 200 Myr was between the mid-Jurassic (~ 170 Myr ago) and the mid-Cretaceous (~ 120 Myr ago) when average reversal frequency decreased from > 8 Myr-1 to < 0.1 Myr-1, mean field intensity appeared to increase by a factor of ~ 2, and the pattern of secular variation became much more stable. This transition was coincident with a major TPW event that probably moved patches of high CMB heat flux towards higher latitudes, a process which geodynamo models suggest would cause changes to geomagnetic behaviour similar to those observed. Consequently, we suspect that TPW played a role in causing this transition. TPW may not be

  2. Very intense geomagnetic storms and their relation to interplanetary and solar active phenomena

    NASA Astrophysics Data System (ADS)

    Szajko, N. S.; Cristiani, G.; Mandrini, C. H.; Dal Lago, A.

    2013-05-01

    We revisit previous studies in which the characteristics of the solar and interplanetary sources of intense geomagnetic storms have been discussed. In this particular analysis, using the Dst time series, we consider the very intense geomagnetic storms that occurred during Solar Cycle 23 by setting a value of Dstmin⩽-200nT as threshold. After carefully examining the set of available solar and in situ observations from instruments aboard the Solar and Heliospheric Observatory (SOHO) and the Advanced Composition Explorer (ACE), complemented with data from the ground, we have identified and characterized the solar and interplanetary sources of each storm. That is to say, we determine the time, angular width, plane-of-the-sky, lateral expansion, and radial velocities of the source coronal mass ejection (CME), the type and heliographic location of the CME solar source region (including the characteristics of the sunspot groups), and the time duration of the associated flare. After this, we investigate the overall characteristics of the interplanetary (IP) main-phase storm driver, including the time arrival of the shock/disturbance at 1 AU, the type of associated IP structure/ejecta, the origin of a prolonged and enhanced southward component (Bs) of the IP field, and other characteristics related to the energy injected into the magnetosphere during the storm (i.e. the solar wind maximum convected electric field, Ey). The analyzed set consists of 20 events, some of these are complex and present two or more Dst minima that are, in general, due to consecutive solar events. The 20 storms are distributed along Solar Cycle 23 (which is a double-peak cycle) in such a way that 15% occurs during the rising phase of the cycle, 45% during both cycle maxima, and, surprisingly, 40% during the cycle descending phase. This latter set includes half of the superstorms and the only cycle extreme event. 85% of the storms are associated to full halo CMEs and 10% to partial halo events. One

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

    NASA Astrophysics Data System (ADS)

    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

  4. First results on climatological response of Indian low latitude ionosphere to geomagnetic storms during solar cycle 23 and 24

    NASA Astrophysics Data System (ADS)

    Suresh, Sunanda; Dashora, Nirvikar

    2016-07-01

    For the first time, a climatological response of low latitude ionosphere to geomagnetic storms is presented using long term global ionospheric maps (GIM) data from June 1998 to June 2015 covering two solar cycles 23 and 24. The results are not only the first from Indian region but also the first around the globe to bring latitudinal character of daytime ionospheric storms with use of newly defined criteria. The results are presented for daytime forenoon and afternoon sectors under minor, moderate and major ionospheric storm categories based on minimum Dst index criterion. For the first time the effectiveness of storms is identified using monthly standard deviation as an indicator of the day-to-day variability in equatorial and low latitude ionosphere. Thus results on climatology are definitive and form a data base that would be comparable to statistical results from any other longitude and time. Seasonal statistics for total storms, effective positive and negative storms, and amplitude of mean seasonal perturbation in total electron content are obtained. Total and effective storms are found to be higher in solar cycle 23 than in 24 and only couple of effective storms occurred during low solar activity 2007-2009 that also in minor category. Afternoon sector is found to be favourable for occurrence of maximum number of effective positive storms. A latitudinal preference is found for a given storm to be effective in either time sectors. Equinoctial asymmetry in ionospheric response both in terms of occurrence and perturbation amplitude is found. September equinoxes are found to bear maximum total, effective positive and negative storms. Winters are found more prone to negative storms whereas summers have recorded minimum number of either of storms and minimum perturbation amplitudes.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  6. The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Baker, D. N.; Fennell, J. F.; Blake, J. B.; Larsen, B. A.; Skoug, R. M.; Funsten, H. O.; Friedel, R. H. W.; Reeves, G. D.; Spence, H. E.; Mitchell, D. G.; Lanzerotti, L. J.; Rodriguez, J. V.

    2015-09-01

    Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute more significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O+ is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O+. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. The results show that the measured ring current ions contribute about half of the Dst depression.

  7. Global images of trapped ring current ions during main phase of 17 March 2015 geomagnetic storm as observed by TWINS

    NASA Astrophysics Data System (ADS)

    Perez, J. D.; Goldstein, J.; McComas, D. J.; Valek, P.; Fok, M.-C.; Hwang, Kyoung-Joo

    2016-07-01

    A unique view of the trapped particles in the inner magnetosphere provided by energetic neutral atom (ENA) imaging is used to observe the dynamics of the spatial structure and the pitch angle anisotropy on a global scale during the last 6 h of the main phase of a large geomagnetic storm (minimum SYM-H = -230 nT) that began on 17 March 2015. Ion flux and pressure anisotropy obtained from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) ENA images are shown. The ion flux shows two peaks, an inner one at approximately radii = 3-4 RE in the dusk-to-midnight sector and an outer peak at radii = 8-9 RE prior to midnight. The inner peak is relatively stationary during the entire period with some intensification during the final steep decline in SYM-H to its minimum. The outer peak shows the significant temporal variation brightening and dimming and finally disappearing at the end of the main phase. The pressure anisotropy shows the expected perpendicular pitch angles inside of L = 6 but shows parallel pitch angles at greater L values. This is interpreted as consistent with pitch angle-dependent drift as modeled in the Tsy05 magnetic field and Comprehensive Inner Magnetosphere-Ionosphere simulations. The TWINS results are compared directly with Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)-A measurements. Using 15 min snapshots of flux and pressure anisotropy from TWINS along the path of RBSPICE-A during the 6 h focused upon in this study, the essential features displayed in the TWINS global images are supported.

  8. Global Images of Trapped Ring Current Ions During Main Phase of 17 March 2015 Geomagnetic Storm as Observed by TWINS

    NASA Technical Reports Server (NTRS)

    Perez, J. D.; Goldstein, J.; McComas, D. J.; Valek, P.; Fok, Mei-Ching; Hwang, Kyoung-Joo

    2016-01-01

    A unique view of the trapped particles in the inner magnetosphere provided by energetic neutral atom (ENA) imaging is used to observe the dynamics of the spatial structure and the pitch angle anisotropy on a global scale during the last 6 h of the main phase of a large geomagnetic storm (minimum SYM-H 230 nT) that began on 17 March 2015. Ion flux and pressure anisotropy obtained from Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) ENA images are shown. The ion flux shows two peaks, an inner one at approximately radii 34 RE in the dusk-to-midnight sector and an outer peak at radii 89 RE prior to midnight. The inner peak is relatively stationary during the entire period with some intensification during the final steep decline in SYM-H to its minimum. The outer peak shows the significant temporal variation brightening and dimming and finally disappearing at the end of the main phase. The pressure anisotropy shows the expected perpendicular pitch angles inside of L 6 but shows parallel pitch angles at greater L values. This is interpreted as consistent with pitch angle-dependent drift as modeled in the Tsy05 magnetic field and Comprehensive Inner Magnetosphere-Ionosphere simulations. The TWINS results are compared directly with Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)-A measurements. Using 15 min snapshots of flux and pressure anisotropy from TWINS along the path of RBSPICE-A during the 6 h focused upon in this study, the essential features displayed in the TWINS global images are supported.

  9. Equatorial counterelectrojets during geomagnetic storms and their possible dynamos in the magnetosphere

    NASA Astrophysics Data System (ADS)

    Kikuchi, T.; Hashimoto, K. K.; Ebihara, Y.; Tsuji, Y.; Veenadhari, B.; Nishimura, T.; Tanaka, T.; Fujita, S.; Nagatsuma, T.

    2012-12-01

    During the substorm growth phase and storm main phase, the high pressure plasma accumulated in the cusp and mantle regions activates a dynamo for the dawn-to-dusk convection electric field and the Region-1 field-aligned currents (R1 FACs) [Tanaka, 1995]. The electric field and FACs are conveyed by the shear Alfven waves to the polar ionosphere and the electric field extends promptly to low latitude through the Earth-ionosphere waveguide [Kikuchi and Araki, 1979]. The electric field drives the DP2 currents at mid latitudes [Wilson et al., 2001; Tsuji et al., 2012] and intensifies the equatorial electrojet (EEJ) [Kikuchi et al., 1996, 2008]. The convection electric field extends to the inner magnetosphere promptly [Nishimura et al., 2009] and energizes the plasma in the partial ring current region with the help of the gradient and curvature drift [Ebihara and Ejiri, 2000], which in turn works as a dynamo for the dusk-to-dawn electric field and the R2 FACs. The dusk-to-dawn electric field causes the counterelectrojet (CEJ) at the equator when the IMF turns northward [Rastogi, 1975]. The CEJ often appears during substorms [Kobea et al., 2000; Kikuchi et al., 2000]. Both the R1 and R2 FACs are intensified by the substorm expansion, with the R2 FACs strong enough to cause the CEJ [Hashimoto et al., 2011]. The CEJ often occurs during the recovery phase of geomagnetic storms [Kikuchi et al., 2008; Tsuji et al., 2012], while the CEJ also appears during the storm main phase under the relatively stable southward IMF [Fejer et al., 2007; Veenadhari et al., 2010]. In this paper, we analyzed several storm events to identify the dynamo for the stormtime CEJ. The disturbance dynamo is a commonly accepted dynamo for the long lasting stormtime CEJ [Blanc and Richmond, 1980; Fejer and Scherliess 1997]. However, the observed rapid and periodic development of the CEJ should be attributed to the R2 FACs generated in the inner magnetosphere. Based on the magnetometer and radar

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Panovska, Sanja; Constable, Catherine

    2015-04-01

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

  12. Modeling of Coronal Mass Ejections That Caused Particularly Large Geomagnetic Storms Using ENLIL Heliosphere Cone Model

    NASA Astrophysics Data System (ADS)

    Taktakishvili, A.; Pulkkinen, A.; MacNeice, P. J.; Kuznetsova, M. M.; Hesse, M.; Odstrcil, D.

    2010-12-01

    The largest geomagnetic storms are caused by the solar coronal mass ejections (CMEs). In our previous paper (Taktakishvili et al., [2009]) we reported the results of modeling 14 selected well observed strong halo CME events using the WSA/ENLIL cone model combination. In that study the cone model input parameters were obtained from white-light coronagraph images of the CME events using the analytical method developed by Xie et al [ 2004 ]. This work verified that coronagraph input gives reasonably good results for the CME arrival time prediction. Recently Pulkkinen et al., [2009] developed a novel method for automatic determination of cone model parameters. This approach combines standard image processing techniques and a novel inversion routine to derive the cone parameters. The present work extends our previous studies by addressing more CME events. The approach in this paper is different from our previous study: we started from addressing 36 particularly strong geomagnetic storms, then tried to associate them with particular CMEs using SOHO/LASCO catalogue, and finally modeled these CMEs using WSA/ENLIL cone model. This approach is addressing space weather forecasting and operational needs. We employed both analytical and automatic methods to determine cone model input parameters. We examined the CME arrival times and magnitude of impact at 1 AU for both techniques. The results of the simulations were compared with the ACE satellite observations. This comparison demonstrated that WSA/ENLIL model combination with coronograph input gives reasonably good results for the CME arrival times for this set of "geo-effective" CME events as well. References: Taktakishvili, A., M. Kuznetsova, P. Macneice, M. Hesse, L. Rastaetter, A. Pulkkinen, A. Chulaki and D. Odstrci (2009), Validation of the coronal mass ejection predictions at the Earth orbit estimated by ENLIL heliosphere cone model, Space Weather,7, S03004,doi10.1029/2008SW000448. Xie, H., L. Ofman, and G. Lawrence

  13. Long-duration geomagnetic storm effects on the D region of the ionosphere: Some case studies using VLF signal

    NASA Astrophysics Data System (ADS)

    Choudhury, Abhijit; De, Barin Kumar; Guha, Anirban; Roy, Rakesh

    2015-01-01

    present work investigates the effects of long-duration geomagnetic storms on VLF signal during ionospheric sunrise time, commonly known as D Layer Preparation Time (DLPT) depth. The VLF signal at 19.8 kHz transmitted from Northwest Cape, Australia, and received at a low-latitude station, Tripura, India, is used for the present analysis. The data for the analysis are selected from November 2008 to October 2011. In the active period of the geomagnetic storms, the average DLPT depth is found to have a negative correlation coefficient of 0.91 with geomagnetic Ap index. It is also found that with each 10 unit increase of Ap index, the DLPT depth (the day and night asymmetry level) changes by 1.25 dB. The results are supported with modeled International Reference Ionosphere (IRI) electron density data and DLPT depth at 71 km height for the three positions, namely, receiver position, signal hop position, and the transmitter position along the total Great Circle Path. It is found that the receiver position electron density is the main controlling factor for DLPT depth. The correlation between IRI electron density and DLPT depth increases from -0.13 at transmitter position to -0.33 at the first hop position, to -0.46 at the receiver position, respectively. The percentage change of post storm electron density, at 71 km height, is found to increase by more than 100% at the receiver position. The results are discussed on the basis of the electron density changes over the signal propagation path, mainly caused by the geomagnetic storms.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Ionosphere-magnetosphere structure during a geomagnetic storm based on measurements in the morning auroral zone

    SciTech Connect

    Denig, W.F.; Rich, F.J.

    1986-01-01

    Measurements of field-aligned currents (FAC's), convection electric fields, and precipitating electrons were made by the S3 2 satellite in the midmorning time sectors of both the northern and southern high-latitude ionospheres before and during a geomagnetic storm. The patterns of electric fields and FAC's did not match the standard configuration of two-cell convection and the region 1/region 2 FAC's. In particular, near the beginning of the main phase of the storm an intense (242 m V/m) convection electric field and an extra FAC were observed just poleward of the region 1 current in the southern hemisphere. The observations, made over a period of at least 3 hours, were consistent with a quasi-steady three-cell convection pattern with stresses from a strong B/sub y/ component of the interplanetary magnetic field (IMF). An analysis of the particle and field data from within the region of the intense convection electric field is in sharp disagreement with the single particle motion model of Lyons (1980) and implies that a significant portion of the measured FAC was from ionospheric ions. Finally, large-amplitude AC electric waves from broadband electrostatic noise (BEN) were present in the high-altitude southern (or winter) passes but not in the northern passes at lower altitudes. In general, BEN was observed occasionally by S3 2 within the high-altitude (1000-1500 km) winter auroral regions but not detected during other seasons or at lower altitudes. The implication of these measurements is that the low-altitude limit for the region of field aligned potentials is determined by the local plasma density.

  17. A broad-band VLF-burst associated with ring-current electrons. [geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Maeda, K.

    1982-01-01

    Frequency band broadening takes place just outside of the nighttime plasmasphere, where the density of cold plasma is known to be very low during the later phase of a geomagnetic storm. Instead of the gradual broadening of several hours duration, a burst type broadening of VLF emission lasting less than ten minutes was observed by Explorer 45 in a similar location. The magnetic field component of this emission is very weak and the frequency spreads below the local half electron cyclotron frequency. Corresponding enhancement of the anisotropic ring current electrons is also very sudden and limited below the order of 10 keV without significant velocity dispersion, in contrast to the gradual broadening events. The cause of this type of emission band spreading can be attributed to the generation of the quasielectrostatic whistler mode emission of short wavelength by hot bimaxwellian electrons surging into the domain of relatively low density magnetized cold plasma. The lack of energy dispersion in the enhanced electrons indicates that the inner edge of the plasma sheet, the source of these hot electrons, is not far from the location of this event.

  18. Generation of large-scale equatorial F-region plasma depletions during geomagnetic storms: A review

    NASA Astrophysics Data System (ADS)

    Sahai, Y.; Fagundes, P.; Bittencourt, J.; Pimenta, A.

    All-sky imaging observations of the F-region OI 630 nm nightglow emission allow us to visualize large - scale equatorial plasma depletions, generally known as transequatorial plasma bubbles. These quasi north south direction aligned- ionospheric plasma depletions are o tical signatures of strong range type equatorialp spread-F. An extensive data base of the OI 630 nm emission all-sky imaging- observations has been obtained at Cachoeira Paulista (22.7o S, 45.0 o W; dip latitude ~16o S), Brazil, between the years 1987 and 2000. An analysis of these observations revealed that normally large-scale ionospheric plasma depletions do not occur during the months of May to August (southern winter) in the Brazilian sector. However, large-scale ionospheric plasma depletions during thes e months have been observed on several occasions in association with geomagnetic storms. In this paper, a detailed analysis of the events when large - scale ionospheric plasma depletions were initiated and evolved during magnetic disturbances will be present ed and discussed.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  1. 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

    DTIC Science & Technology

    2008-01-01

    energy electrons based sites such as at Poker Flat , Alaska and Kangerlus- or other differences in the energy distribution during the suaq, Greenland...and riometer observations from the Alaska chain in Poker ship is linear or of higher order [Hecht et al., 2006]. Flat and Fort Yukon, photometric...Coordinates of Ground-Based Locations Site Geographic Lat Geographic Long Geomagnetic Lat Geomagnetic Long Fort Yukon 66.6 214.7 67.3 -94.7 Poker Flat 65.1

  2. Statistical analysis of the geomagnetic response to different solar wind drivers and the dependence on storm intensity

    NASA Astrophysics Data System (ADS)

    Katus, R. M.; Liemohn, M. W.; Ionides, E. L.; Ilie, R.; Welling, D. T.

    2014-12-01

    Geomagnetic storms start with activity on the Sun that causes propagation of magnetized plasma structures in the solar wind. The type of solar activity is used to classify the plasma structures as being either interplanetary coronal mass ejection (ICME) or corotating interaction region (CIR)-driven. The ICME-driven events are further classified as either magnetic cloud (MC)-driven or sheath (SH)-driven by the geoeffective structure responsible for the peak of the storm. The geoeffective solar wind flow then interacts with the magnetosphere producing a disturbance in near-Earth space. It is commonly believed that a SH-driven event behaves more like a CIR-driven event than a MC-driven event; however, in our analysis this is not the case. In this study, geomagnetic storms are investigated statistically with respect to the solar wind driver and the intensity of the events. We use the Hot Electron and Ion Drift Integrator (HEIDI) model to simulate the inner magnetospheric hot ion population during all of the storms classified as intense (Dstmin < - 100 nT) within solar cycle 23 (1996-2005). HEIDI is configured four different ways using either the Volland-Stern or self-consistent electric field and either event-based Los Alamos National Lab (LANL) magnetospheric plasma analyzer (MPA) data or a reanalyzed lower resolution version of the data that provides spatial resolution. Presenting the simulation results, geomagnetic data, and solar wind data along a normalized epoch timeline shows the average behavior throughout a typical storm of each classification. The error along the epoch timeline for each HEIDI configuration is used to rate the model's performance. We also subgrouped the storms based on the magnitude of the minimum Dst. We found that typically the LANL MPA data provides the best outer boundary condition. Additionally, the self-consistent electric field better reproduces SH and MC-driven events throughout most of the storm timeline but the Volland-Stern electric

  3. The Effects of Neutral Inertia on Ionospheric Currents in the High-Latitude Thermosphere Following a Geomagnetic Storm

    NASA Technical Reports Server (NTRS)

    Deng, W.; Killeen, T. L.; Burns, A. G.; Roble, R. G.; Slavin, J. A.; Wharton, L. E.

    1993-01-01

    Results of an experimental and theoretical investigation into the effects of the time dependent neutral wind flywheel on high-latitude ionospheric electrodynamics are presented. The results extend our previous work which used the National Center for Atmospheric Research Thermosphere/Ionosphere General Circulation Model (NCAR TIGCM) to theoretically simulate flywheel effects in the aftermath of a geomagnetic storm. The previous results indicated that the neutral circulation, set up by ion-neutral momentum coupling in the main phase of a geomagnetic storm, is maintained for several hours after the main phase has ended and may dominate height-integrated Hall currents and field-aligned currents for up to 4-5 hours. We extend the work of Deng et al. to include comparisons between the calculated time-dependent ionospheric Hall current system in the storm-time recovery period and that measured by instruments on board the Dynamics Explorer 2 (DE 2) satellite. Also, comparisons are made between calculated field-aligned currents and those derived from DE 2 magnetometer measurements. These calculations also allow us to calculate the power transfer rate (sometimes called the Poynting flux) between the magnetosphere and ionosphere. The following conclusions have been drawn: (1) Neutral winds can contribute significantly to the horizontal ionospheric current system in the period immediately following the main phase of a geomagnetic storm, especially over the magnetic polar cap and in regions of ion drift shear. (2) Neutral winds drive Hall currents that flow in the opposite direction to those driven by ion drifts. (3) The overall morphology of the calculated field-aligned current system agrees with previously published observations for the interplanetary magnetic field (IMF) B(sub Z) southward conditions, although the region I and region 2 currents are smeared by the TI(ICM model grid resolution. (4) Neutral winds can make significant contributions to the field-aligned current

  4. Alfvénic field-aligned currents, ion upflow and electron precipitation during large geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Hatch, Spencer; LaBelle, James; Chaston, Christopher

    2016-04-01

    We present four years of FAST observations of Alfvénic field-aligned currents (FACs) in the Northern Hemisphere coincident with 40 moderate (Dst < -50 nT) to very large geomagnetic storms. Superposed epoch analysis of Alfvénic activity of storm periods demonstrate a sharp increase in the probability of AlfvÉn wave occurrence just after storm commencement, and analysis based on storm phase shows that the probability of Alfvén wave occurrence increases by more than a factor of 5 on both dayside and nightside. Additionally, recently reported Van Allen Probes measurements in the magnetosphere imply a region (˜60-68 degrees invariant latitude) in the nightside ionosphere where Alfvén waves are statistically likely to be observed during storm main phase; we report statistical observations during main phase showing that this region instead corresponds to both intense electron precipitation (>10 mW m-2) and strong upflowing ion number flux (> 108 cm^{-2 s-1), while observed Alfvénic FAC occurrence rates are diminished relative to Van Allen Probes measurements. FAST observations also indicate that the most intense electron precipitation associated with Alfvénic FACs occurs pre-midnight during storm recovery phase.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    USGS Publications Warehouse

    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.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Geomagnetic Storm Effects in the Low- to Middle-Latitude Upper Thermosphere

    NASA Technical Reports Server (NTRS)

    Burns, A. G.; Killeen, T. L.; Deng, W.; Carignan, G. R.; Roble, R. G.

    1995-01-01

    In this paper, we use data from the Dynamics Explorer 2 (DE 2) satellite and a theoretical simulation made by using the National Center for Atmospheric Research thermosphere/ionosphere general circulation model (NCAR-TIGCM) to study storm-induced changes in the structure of the upper thermosphere in the low- to middle-latitude (20 deg-40 deg N) region of the winter hemisphere. Our principal results are as follows: (1) The winds associated with the diurnal tide weaken during geomagnetic storms, causing primarily zonally oriented changes in the evening sector, few changes in the middle of the afternoon, a combination of zonal and meridional changes in the late morning region, and mainly meridional changes early in the morning; (2) Decreases in the magnitudes of the horizontal winds associated with the diurnal tide lead to a net downward tendency in the vertical winds blowing through a constant pressure surface; (3) Because of these changes in the vertical wind, there is an increase in compressional heating (or a decrease in cooling through expansion), and thus temperatures in the low- to middle-latitudes of the winter hemisphere increase; (4) Densities of all neutral species increase on a constant height surface, but the pattern of changes in the O/N2 ratio is not well ordered on these surfaces; (5) The pattern of changes in the O/N2 ratio is better ordered on constant pressure surfaces. The increases in this ratio on constant pressure surfaces in the low- to middle-latitude, winter hemisphere are caused by a more downward tendency in the vertical winds that blow through the constant pressure surfaces. Nitrogen-poor air is then advected downward through the pressure surface, increasing the O/N2 ratio; (6) The daytime geographical distribution of the modeled increases in the O/N2 ratio on a constant pressure surface in the low- to middle-latitudes of the winter hemisphere correspond very closely with those of increases in the modeled electron densities at the F2 peak.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Geomagnetic secular variations at the Permo-Triassic boundary

    NASA Astrophysics Data System (ADS)

    Pavlov, Vladimir; Veselovskiy, Roman; Fetisova, Anna; Latyshev, Anton; Fluteau, Frederic

    2014-05-01

    Study of changes in geomagnetic secular variations through geological time is essential to document the Earth's magnetic field evolution and provides an important constraint for geodynamo modeling. Moreover, knowledge of the secular variations value for any specific geological epoch (paleosecular variations - PSV) may give an additional tool to constrain the duration of emplacement and cooling of various magmatic bodies including flows, dykes and sills. In this report we present the result of study of the PSV at the Permo-Triassic boundary (~252 Ma), based on the paleomagnetic data, obtained from numerous (N>100) volcanic flows of the Siberian traps exposed in series of sections located in Norilsk and Maymecha-Kotuy regions in the North-West and North of the Siberian platform. Our data, taken together with similar data from other regions (Sementau, East Kazakhstan; Emeichan, China) indicates that the amplitude of PSV at the Permo-Triassic boundary was about the same or a little lower than in Late Cenozoic during last 5 milllions years. The low (comparing with expected one) value of PSV recorded in several large sills from Angara-Bratsk region (southern Siberian platform) indicates that these sills was formed very fast during the time interval less than, at least, several thousand years. Especially this conclusion is interesting for so called Tolstomyss sill, which, in fact, represents a huge field of associated tuffs, sills, dykes and volcanics, extended over the distance more than 200 km. This result can be considered as a further indication of very fast emplacement of the Siberian traps and their link with the Permo-Triassic catastrophe.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

    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

  18. Dynamo currents representing geomagnetic L variation demonstrated by a multi-layer ionospheric model

    NASA Astrophysics Data System (ADS)

    Xu, W.-Y.; Tschu, K.-K.; Matsushita, S.

    1984-05-01

    A multi-layer ionospheric model and lunar (2,2) tidal mode have been used to calculate dynamo current systems representing lunar geomagnetic semidiurnal variations. Since both the height variation of the ionospheric conductivities and latitudinal dependence of the height of the conductivity peaks have been taken into account, the dynamo current systems agree with equivalent ones (estimated from geomagnetic data) better than those for a thin shell model of the ionospheric conductivity, especially in the polar region.

  19. Altitude variations in the thermosphere mass density response to geomagnetic activity during the recent solar minimum

    NASA Astrophysics Data System (ADS)

    Liu, X.; Thayer, J. P.; Burns, A.; Wang, W.; Sutton, E.

    2014-03-01

    Accelerometer data from coplanar orbits of Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites were used to study the complex altitude and latitude variations of the thermosphere mass density response to geomagnetic activity during 1-10 December 2008 near 09 LT. Helium number densities near 500 km altitude were extracted from the CHAMP and GRACE measurements and clearly show the presence of a winter hemisphere helium bulge. This recent extreme solar minimum indicates that wintertime helium concentrations exceed NRLMSISE-00 model estimates by 30%-70% during quiet geomagnetic activity after adjusting F10.7 input into MSIS. The perturbation in mass density from quiet to active conditions is found to be less enhanced in the winter hemisphere at the higher GRACE altitudes (25%) than at the lower CHAMP altitudes (60%) and is attributed to dynamic behavior in the helium/oxygen transition. The investigation revealed the maximum storm time density perturbation to occur near the He/O transition region with a much weaker maximum near the O/N2 transition region. The altitude of maximum density perturbation occurs where the perturbation in the weighted pressure scale height is equal and opposite to the perturbation in the weighted mean molecular weight scale height. The altitude structure of density scale height perturbation is significantly influenced by the changes in the molecular weight scale height and can account for 50% of the change in mass density scale height in a region correspondingly close to the He/O transition during the 2008 solar minimum period.

  20. Statistical analysis of the geomagnetic response to different solar wind drivers and the dependence on storm intensity

    NASA Astrophysics Data System (ADS)

    Katus, R. M.; Liemohn, M. W.; Ionides, E. L.; Ilie, R.; Welling, D.; Sarno-Smith, L. K.

    2015-01-01

    storms start with activity on the Sun that causes propagation of magnetized plasma structures in the solar wind. The type of solar activity is used to classify the plasma structures as being either interplanetary coronal mass ejection (ICME) or corotating interaction region (CIR) driven. The ICME-driven events are further classified as either magnetic cloud (MC) driven or sheath (SH) driven by the geoeffective structure responsible for the peak of the storm. The geoeffective solar wind flow then interacts with the magnetosphere producing a disturbance in near-Earth space. It is commonly believed that a SH-driven event behaves more like a CIR-driven event than a MC-driven event; however, in our analysis this is not the case. In this study, geomagnetic storms are investigated statistically with respect to the solar wind driver and the intensity of the events. We use the Hot Electron and Ion Drift Integrator (HEIDI) model to simulate the inner magnetospheric hot ion population during all of the storms classified as intense (Dstmin ≤ -100 nT) within solar cycle 23 (1996-2005). HEIDI is configured four different ways using either the Volland-Stern or self-consistent electric field and either event-based Los Alamos National Laboratory (LANL) magnetospheric plasma analyzer (MPA) data or a reanalyzed lower resolution version of the data that provides spatial resolution. Presenting the simulation results, geomagnetic data, and solar wind data along a normalized epoch timeline shows the average behavior throughout a typical storm of each classification. The error along the epoch timeline for each HEIDI configuration is used to rate the model's performance. We also subgrouped the storms based on the magnitude of the minimum Dst. We found that typically the LANL MPA data provide the best outer boundary condition. Additionally, the self-consistent electric field better reproduces SH- and MC-driven events throughout most of the storm timeline, but the Volland-Stern electric

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

    NASA Astrophysics Data System (ADS)

    Lacasa, Lucas

    2012-01-01

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

  2. Geophysical variables and behavior: LXXX. Periodicities and energetic characteristics of a strobe-light luminosity during a geomagnetic storm.

    PubMed

    Persinger, M A; Hart, B; Thomas, A W

    1996-04-01

    A videotape of a "strobe-light" luminosity that occurred in northern Ontario for several minutes during the evening of 6 October, 1994, at the time of a geomagnetic storm, was analyzed frame by frame. Brightness of the flashes decreased over the time of the observation. The interflicker intervals displayed phase-shifted periodicities that would be compatible with a rotating electromagnetic dipole and with the observations of the witnesses. The time of the occurrence and the dynamics of the luminosity were consistent with the predictions of the tectonic strain hypothesis.

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

    USGS Publications Warehouse

    Gannon, J.L.

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. Solar and interplanetary sources of major geomagnetic storms (Dst <= -100 nT) during 1996-2005

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    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 ≤ -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. On the basis of 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 (Bs), 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, 11 (13%) in quiet Sun

  6. GPS observations of the ionospheric F2-layer behavior during the 20th November 2003 geomagnetic storm over South Korea

    NASA Astrophysics Data System (ADS)

    Jin, Shuanggen; Luo, O. F.; Park, P.

    2008-12-01

    The ionospheric F2-layer peak density (NmF2) and its height (hmF2) are of great influence on the shape of the ionospheric electron density profile Ne (h) and may be indicative of other physical processes within the ionosphere, especially those due to geomagnetic storms. Such parameters are often estimated using models such as the semiempirical international reference ionosphere (IRI) models or are measured using moderately priced to expensive instrumentation, such as ionosondes or incoherent scatter radars. Global positioning system (GPS) observations have become a powerful tool for mapping high-resolution ionospheric structures, which can be used to study the ionospheric response to geomagnetic storms. In this paper, we describe how 3-D ionospheric electron density profiles were produced from data of the dense permanent Korean GPS network using the tomography reconstruction technique. These profiles are verified by independent ionosonde data. The responses of GPS-derived parameters at the ionospheric F2-layer to the 20th November 2003 geomagnetic storm over South Korea are investigated. A fairly large increase in the electron density at the F2-layer peak (the NmF2) (positive storm) has been observed during this storm, which is accompanied by a significant uplift in the height of the F2 layer peak (the hmF2). This is confirmed by independent ionosonde observations. We suggest that the F2-layer peak height uplift and NmF2 increase are mainly associated with a strong eastward electric field, and are not associated with the increase of the O/N2 ratio obtained from the GUVI instruments aboard the TIMED satellite. It is also inferred that the increase in NmF2 is not caused by the changes in neutral composition, but is related to other nonchemical effects, such as dynamical changes of vertical ion motions induced by winds and E × B drifts, tides and waves in the mesosphere/lower thermosphere region, which can be dynamically coupled upward to generate ionospheric

  7. Different geomagnetic indices as an indicator for geo-effective solar storms and human physiological state

    NASA Astrophysics Data System (ADS)

    Dimitrova, Svetla

    2008-02-01

    A group of 86 healthy volunteers were examined on each working day during periods of high solar activity. Data about systolic and diastolic blood pressure, pulse pressure, heart rate and subjective psycho-physiological complaints were gathered. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters. The factors were as follows: (1) geomagnetic activity estimated by daily amplitude of H-component of the local geomagnetic field, Ap- and Dst-index; (2) gender; and (3) the presence of medication. Average values of systolic, diastolic blood pressure, pulse pressure and subjective complaints of the group were found to increase significantly with geomagnetic activity increment.

  8. Comparative dynamics of relativistic electron fluxes during two geomagnetic storms on 17-18 March and on 22-23 June 22-23 in 2015

    NASA Astrophysics Data System (ADS)

    Vlasova, Natalia; Kalegaev, Vladimir; Beresneva, Evgeniya; Stanislav, Ganitskiy

    2016-07-01

    The role of solar wind in the outer Earth`s radiation belt dynamics is under consideration during the last decades. Unfortunately, the physical mechanisms that control the loss and acceleration of the magnetospheric relativistic electron fluxes are not evident until now. In this study we compared and contrasted some features of relativistic electron flux dynamics during two largest geomagnetic storms in 2015 (17-18 March and 22-23 June) having the similar Dst-variations profiles and amplitudes (~200 nT). Analysis of experimental data from Van Allen Probes (RBSP), GOES, Electro, POES, Meteor satellites was combined with theoretical investigations on the base of the A2000 model of the magnetospheric magnetic field. Multipoint observations at GEO and LEO show the dramatic changes in the MeV electron populations during the main phase of the magnetic storms. We found the solar wind and IMF variations responsible for large-scale magnetospheric current system changes that reveal themselves in the relativistic electron flux dynamics.

  9. ong-term trends of foE and geomagnetic activity variations

    NASA Astrophysics Data System (ADS)

    Mikhailov, A. V.; de La Morena, B. A.

    2003-03-01

    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.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Variation of curve number with storm depth

    NASA Astrophysics Data System (ADS)

    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

  13. Variations in geomagnetic field and temperature in Spain during the past millennium

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    The archaeomagnetic studies are conducted for the collection of coated ceramic samples from the Albarracin archaeological monument in Spain dated to the 10-20th centuries A.D. The pattern of variations in geomagnetic field intensity during this time interval is identified. The behavior of geomagnetic intensity is dominated by a decreasing trend (from ˜80 to 40 μT). The variation with a characteristic time of a few hundred years is the most striking one. Investigation of the material from this collection by the method of rehydroxylation provided the temperature estimates for this region of Spain for the time interval of pottery production. The temperature variations generally tend to increase, while the main trend in the variations of geomagnetic intensity is decreasing. The time series of temperature and intensity of the main magnetic field contain variations with close characteristic times shifted in time so that the changes in temperature go somewhat ahead of the changes in the geomagnetic field. It was previously suggested to improve the accuracy and resolution of the obtained variations in the past magnetic field using the method of archaeomagnetic dating of the material from archaeological monuments. The method was tested by dating the pottery kiln material from the El Molon monument, Spain, with the use of the virtual geomagnetic pole curve based on the past magnetic field in the East Europe. The method proved to be quite efficient and promising for dating the archaeological material from all over Europe.

  14. 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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    Barlow, Peter W.; Fisahn, Joachim; Yazdanbakhsh, Nima; Moraes, Thiago A.; Khabarova, Olga V.; Gallep, Cristiano M.

    2013-01-01

    Background Correlative evidence suggests a relationship between the lunisolar tidal acceleration and the elongation rate of arabidopsis roots grown under free-running conditions of constant low light. Methods Seedlings of Arabidopsis thaliana were grown in a controlled-climate chamber maintained at a constant temperature and subjected to continuous low-level illumination from fluorescent tubes, conditions that approximate to a ‘free-running’ state in which most of the abiotic factors that entrain root growth rates are excluded. Elongation of evenly spaced, vertical primary roots was recorded continuously over periods of up to 14 d using high temporal- and spatial-resolution video imaging and were analysed in conjunction with geophysical variables. Key Results and Conclusions The results confirm the lunisolar tidal/root elongation relationship. Also presented are relationships between the hourly elongation rates and the contemporaneous variations in geomagnetic activity, as evaluated from the disturbance storm time and ap indices. On the basis of time series of root elongation rates that extend over ≥4 d and recorded at different seasons of the year, a provisional conclusion is that root elongation responds to variation in the lunisolar force and also appears to adjust in accordance with variations in the geomagnetic field. Thus, both lunisolar tidal acceleration and the geomagnetic field should be considered as modulators of root growth rate, alongside other, stronger and more well-known abiotic environmental regulators, and perhaps unexplored factors such as air ions. Major changes in atmospheric pressure are not considered to be a factor contributing to oscillations of root elongation rate. PMID:23532042

  16. Observations of the UARS Particle Environment Monitor and computation of ionization rates in the middle and upper atmosphere during a geomagnetic storm

    NASA Technical Reports Server (NTRS)

    Sharber, J. R.; Frahm, R. A.; Winningham, J. D.; Biard, J. C.; Lummerzheim, D.; Rees, M. H.; Chenette, D. L.; Gaines, E. E.; Nightingale, R. W.; Imhof, W. L.

    1993-01-01

    In this paper we present observations made by the Particle Environment Monitor (PEM) instruments during the geomagnetic storm of 8-9 November, 1991. Ionization and energy deposition rates as functions of altitude in the middle and upper atmosphere by incident electrons and positive ions in the storm interval are computed. The suite of PEM instruments provides a systematic measurement of energetic particles and their associated X-rays over an energy range not fully covered by previous satellite missions.

  17. Analysis of Geomagnetic Disturbances and Cosmic Ray Intensity Variations in Relation to Medical Data from Rome

    NASA Astrophysics Data System (ADS)

    Giannaropoulou, E.; Papailiou, M.; Mavromichalaki, H.; Tsipis, A.

    2010-07-01

    Over the last few years many studies have been conducted concerning the possible influence of geomagnetic and solar activity and cosmic ray activity on human physiological state and in particular on human cardio - health state. As it is shown the human organism is sensitive to environmental changes and reacts to them through a series of variations of its physiological parameters such as heart rate, arterial systolic and diastolic blood pressure, etc. In this paper daily mean values of heart rate, as they were registered for a group of 2.028 volunteers during medical examinations in the Polyclinico Tor Vergata, Rome, Italy are analyzed in relation to daily cosmic ray intensity variations, as measured by the Neutron Monitor of the University of Athens and daily variations of the geomagnetic indices Dst, Ap and Kp. The results from this study show that geomagnetic activity changes and cosmic rays intensity variations may regulate the human homeostasis.

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

    NASA Astrophysics Data System (ADS)

    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

  19. Variations in the geomagnetic dipole moment during the Holocene and the past 50 kyr

    NASA Astrophysics Data System (ADS)

    Knudsen, Mads Faurschou; Riisager, Peter; Donadini, Fabio; Snowball, Ian; Muscheler, Raimund; Korhonen, Kimmo; Pesonen, Lauri J.

    2008-07-01

    All absolute paleointensity data published in peer-reviewed journals were recently compiled in the GEOMAGIA50 database. Based on the information in GEOMAGIA50, we reconstruct variations in the geomagnetic dipole moment over the past 50 kyr, with a focus on the Holocene period. A running-window approach is used to determine the axial dipole moment that provides the optimal least-squares fit to the paleointensity data, whereas associated error estimates are constrained using a bootstrap procedure. We subsequently compare the reconstruction from this study with previous reconstructions of the geomagnetic dipole moment, including those based on cosmogenic radionuclides ( 10Be and 14C). This comparison generally lends support to the axial dipole moments obtained in this study. Our reconstruction shows that the evolution of the dipole moment was highly dynamic, and the recently observed rates of change (5% per century) do not appear unique. We observe no apparent link between the occurrence of archeomagnetic jerks and changes in the geomagnetic dipole moment, suggesting that archeomagnetic jerks most likely represent drastic changes in the orientation of the geomagnetic dipole axis or periods characterized by large secular variation of the non-dipole field. This study also shows that the Holocene geomagnetic dipole moment was high compared to that of the preceding ˜ 40 kyr, and that ˜ 4 · 10 22 Am 2 appears to represent a critical threshold below which geomagnetic excursions and reversals occur.

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

    NASA Astrophysics Data System (ADS)

    Ou, Jiaming; Du, Aimin

    2016-04-01

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

  1. Regional response of the mesosphere lower thermosphere dynamics over Scandinavia to solar proton events and geomagnetic storms in late October 2003

    NASA Astrophysics Data System (ADS)

    Pancheva, D.; Singer, W.; Mukhtarov, P.

    2007-07-01

    The short-term regional responses of the mesosphere lower thermosphere (MLT) dynamics over Scandinavia to the exceptionally strong solar storms with their accompanying solar proton fluxes on the Earth in late October 2003 have been investigated using radar measurements at Andenes (69°N, 16°E) and Esrange (68°N, 21°E). Several solar activity storms resulted in solar proton events (SPEs) at this time, but a particularly active period of high proton fluxes occurred between 28 and 31 October 2003. The significant temperature drop (˜25 K), detected by the meteor radar at Andenes at altitude ˜90 km, was in line with the enhancement of the proton fluxes and was caused by the dramatic reduction of the ozone in the high-latitude middle atmosphere monitored by satellite measurements. This exceptionally strong phenomenon in late October 2003 was composed of three geomagnetic storms, with the first one occurring in the daytime of 29 October and the other two storms in the nighttime of 29 and 30 October, respectively. The responses of the prevailing wind and the main tides (24- and 12-h tides) were studied in detail. It was found that the response of the MLT dynamics to the first geomagnetic storm occurring in the daytime and accompanied by solar proton fluxes is very different from those to the second and third geomagnetic storms with onsets during the nighttime. Some physical mechanisms have been suggested in order to explain the observed short-term variability of the MLT dynamics. This case study revealed the impact of the SPEs observed in late October 2003 and the timing of the geomagnetic storms on the MLT neutral wind responses observed over Scandinavia.

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

    SciTech Connect

    Borovsky, Joseph E; Cayton, Thomas E; Denton, Michael H

    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.

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

    NASA Astrophysics Data System (ADS)

    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 <0.05) increase in cortisol levels in all three independent groups of people was shown. Amplitude increases in cortisol levels in different groups were about 30% of the observed variation in the

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

    NASA Technical Reports Server (NTRS)

    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.

  5. Deep depletions of total electron content associated with severe mid-latitude gigahertz scintillations during geomagnetic storms

    SciTech Connect

    Ogawa, T.; Kumagai, H.

    1985-07-01

    Using 136-MHz Faraday rotation data obtained at three closely spaced stations, we present evidence that severe nightime gigahertz scintillations, which appear rarely at mid-latitudes around Japan only during geomagnetic storm conditions, are closely associated with deep depletions of total electron content (TEC). The TEC depletions amount to 2--8 x 10/sup 16/ el/m/sup 2/ (10--30% of the background TEC), and their durations range from 10 min to 1 hour. These depletions move northeastward or eastward with velocities between 60 and 260 m/s. The depletions are probably not counterparts of the equatorial bubbles but seem to be formed in localized regions around Japan under complicated and peculiar ionospheric conditions. There is an indication that the oscillation of the F region caused by large-scale TID's propagating from north to south (approx.600 m/s) may initiate the generation of the depletion.

  6. Satellite observations of energy-banded ions during large geomagnetic storms: Event studies, statistics, and comparisons to source models

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Cattell, C. A.; Kozyra, J. U.; Thomsen, M. F.; Lavraud, B.

    2016-07-01

    Energy-banded ions from tens to ten thousands of eV are observed in the low-latitude auroral and subauroral zones during every large (minimum Dst < -150 nT) geomagnetic storm encountered by the FAST satellite. The banded ions persist for many FAST orbits, lasting up to 12 h, in both the northern and southern hemispheres. The energy-banded ions often have more than six distinct bands, and the O+, He+, and H+ bands are often observed at the same energies. The bands are extensive in latitude (~50-75° on the dayside, often extending to 45°) and magnetic local time, covering all magnetic local time over the data set of storms. The distributions are peaked in the perpendicular direction at the altitudes of the FAST satellite (~350-4175 km), although in some cases the precipitating component dominates for the lowest energy bands. At the same time, for some of the events studied in detail, long-lasting intervals of field-aligned energy dispersed ions from ~100 eV to 40 keV are seen in Los Alamos National Laboratory geosynchronous observations, primarily on the dayside and after magnetosheath encounters (i.e., highly compressed magnetosphere). We present both case and statistical studies of the banded ions. These bands are a new phenomenon associated with all large storms, which are distinctly different from other banded populations, and are not readily interpreted using previous models for particle sources, transport, and loss. The energy-banded ions are an energetically important component of the inner magnetosphere during the most intense magnetic storms.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  8. The impact of geomagnetic storms on the US electric power grid

    NASA Astrophysics Data System (ADS)

    Schrijver, C.; Mitchell, S.; Title, A. M.

    2012-12-01

    Large solar explosions are responsible for space weather that can impact technological infrastructure on and around Earth. We study the impacts of geomagnetic activity on the U.S. electric power grid for the period from 1992 through 2010. We find, with more than 3-sigma significance, that approximately 4% of the disturbances in the U.S. power grid reported to the U.S. Department of Energy are attributable to geomagnetic activity. The combination of our results with an economic assessment study by the electric power industry suggests that the average cost to the U.S. economy of non-catastrophic grid disturbances in which space weather conditions are a contributing factor exceeds $3 billion per year. The magnitude of this apparent economic impact warrants extensive follow-up studies to validate, understand, and mitigate against the weak but significant contribution of space weather in power grid disturbances.

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

    PubMed Central

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

    2014-01-01

    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. PMID:25056214

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

    PubMed

    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.

  11. Ionospheric effects at low latitudes during the March 22, 1979, geomagnetic storm

    SciTech Connect

    Fesen, C.G. ); Crowley, G.; Roble, R.G. )

    1989-05-01

    This paper investigates the response of the equatorial ionosphere to the neutral atmosphere perturbations produced by the magnetic storm of March 22, 1979. A numerical model of the equatorial ionosphere is used to calculate the maximum electron densities and F layer heights associated with a storm-perturbed neutral atmosphere and circulation model. Possible electric field perturbations due to the storm are ignored. The neutral atmosphere and dynamics are simulated by the National Center for Atmospheric Research thermospheric general circulation model (TGCM) for the storm day of March 22, 1979, and the preceding quiet day. The most striking feature of the TGCM storm day simulations is the presence of waves in the neutral composition, wind, and temperature fields which propagate from high latitudes to the equator. The TGCM-calculated fields for the two days are input into a low-latitude ionosphere model which calculates n{sub max} and h{sub max} between {plus minus}20{degree}dip latitude. The calculated nighttime 6300-{angstrom} airglow emission and the altitude profiles of electron concentration are also highly perturbed by the storm. Examination of ionosonde data for March 22, 1979, shows remarkable agreement between the measured and predicted changes in f{sub 0}F{sub 2} and h{sub max} near 140{degree}W. Poorer agreement near 70{degree}W may be due to the neglect of electric field perturbations and the approximations inherent in the modeling. The results of these simulations indicate that the major factor influencing the storm time ionospheric behavior in this case is the neutral wind.

  12. Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, Atsuki; Koyama, Yukinobu; Nose, Masahito; Hori, Tomoaki; Otsuka, Yuichi; Yatagai, Akiyo

    2014-12-01

    Characteristics of long-term variation in the amplitude of solar quiet (Sq) geomagnetic field daily variation have been investigated using 1-h geomagnetic field data obtained from 69 geomagnetic observation stations within the period of 1947 to 2013. The Sq amplitude observed at these geomagnetic stations showed a clear dependence on the 10- to 12-year solar activity cycle and tended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle 23/24 in 2008 to 2009. The relationship between the solar F10.7 index and Sq amplitude was approximately linear but about 53% of geomagnetic stations showed a weak nonlinear relation to the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second-order fitting curve between the solar F10.7 index and Sq amplitude during 1947 to 2013 and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, the majority of trends in the residual Sq amplitude that passed through a trend test showed negative values over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity at 100-km altitude and residual Sq amplitude showed an anti-correlation for about 71% of the geomagnetic stations. Furthermore, the residual Sq amplitude at the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Identification of Possible Intense Historical Solar Storms During the Years 1781-1788 Inferred from Aurorae and Geomagnetic Observations in Rio De Janeiro

    NASA Astrophysics Data System (ADS)

    Vaquero, José M.; Trigo, Ricardo M.

    2006-05-01

    The reconstruction of solar activity during the late 18th century is a puzzle for researchers due to the scarcity of sunspot observations in that epoch. In this work, we analyse some details of the solar activity during the years 1781-1788, inferred from geomagnetic measurements and visual observations of aurorae performed by the Portuguese scientist Bento Sanches Dorta from Rio de Janeiro. We describe in greater detail four large solar storms that induced large changes in daily values of geomagnetic declination and, simultaneously, correspond to visual observations of aurorae described by Sanches Dorta.

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

    NASA Astrophysics Data System (ADS)

    Wu, C. C.; Liou, K.; Socker, D. G.; Howard, R.; Jackson, B. V.; Yu, H. S.; Hutting, L.; Plunkett, S. P.

    2015-12-01

    The first super geomagnetic storm of solar cycle 24 occurred on the "St. Patrick's day" (17 March 2015). Notably, it was a two-step storm. The source of the storm can be traced back to the solar event on March 15, 2015. At ~2:10 UT on that day, SOHO/LASCO C3 recorded a partial halo corona mass ejection (CME) which was associated with a C9.1/1F flare (S22W25) and a series of type II/IV radio bursts. The propagation speed of this CME is estimated to be ~668 km/s during 02:10 - 06:20 UT (Figure 1). An interplanetary (IP) shock, likely driven by the CME, arrived at the Wind spacecraft at 03:59 UT on 17 March (Figure 2). The arrival of the IP shock at the Earth may have caused a sudden storm commencement (SSC) at 04:45 UT on March 17. The storm intensified (Dst dropped to -80 nT at ~10:00 UT) during the crossing of the CME sheath. Later, the storm recovered slightly (Dst ~ -50 nT) after the IMF turned northward. At 11:01 UT, IMF started turning southward again due to the large magnetic cloud (MC) field itself and caused the second storm intensification, reaching Dst = - 228 nT on March 18. We conclude that the St. Patrick day event is a two-step storm. The first step is associated with the sheath, whereas the second step is associated with the MC. Here, we employ a numerical simulation using the global, three-dimensional (3D), time-dependent, magnetohydrodynamic (MHD) model (H3DMHD, Wu et al. 2007) to study the CME propagation from the Sun to the Earth. The H3DMHD model has been modified so that it can be driven by (solar wind) data at the inner boundary of the computational domain. In this study, we use time varying, 3D solar wind velocity and density reconstructed from STELab, Japan interplanetary scintillation (IPS) data by the University of California, San Diego, and magnetic field at the IPS inner boundary provided by CSSS model closed-loop propagation (Jackson et a., 2015). The simulation result matches well with the in situ solar wind plasma and field data at

  18. Interhourly Variability Index of Geomagnetic Activity and Its Use in Deriving the Long-Term Variation of Solar Wind Speed

    DTIC Science & Technology

    2007-10-31

    CONTRACT NUMBER Interhourly variability index of geomagnetic activity and its use in deriving the long-term variation of solar wind speed 5b...detailed derivation of the interhourly variability (IHP) index of geomagnetic activity. The LHV index for a given geomagnetic element is mechanically... index is derived separately for stations in both hemispheres within six longitude sectors spanning the Earth using only local night hours. It is

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Simultaneous stochastic inversion for geomagnetic main field and secular variation. II - 1820-1980

    NASA Technical Reports Server (NTRS)

    Bloxham, Jeremy; Jackson, Andrew

    1989-01-01

    With the aim of producing readable time-dependent maps of the geomagnetic field at the core-mantle boundary, the method of simultaneous stochastic inversion for the geomagnetic main field and secular variation, described by Bloxham (1987), was applied to survey data from the period 1820-1980 to yield two time-dependent geomagnetic-field models, one for the period 1900-1980 and the other for 1820-1900. Particular consideration was given to the effect of crustal fields on observations. It was found that the existing methods of accounting for these fields as sources of random noise are inadequate in two circumstances: (1) when sequences of measurements are made at one particular site, and (2) for measurements made at satellite altitude. The present model shows many of the features in the earth's magnetic field at the core-mantle boundary described by Bloxham and Gubbins (1985) and supports many of their earlier conclusions.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Babayev, Elchin S.; Allahverdiyeva, Aysel A.

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

  4. Multi-instrument observations of plasma features in the Arctic ionosphere during the main phase of a geomagnetic storm in December 2006

    NASA Astrophysics Data System (ADS)

    Wu, Ye-wen; Liu, Rui-yuan; Zhang, Bei-chen; Wu, Zhen-sen; Hu, Hong-qiao; Zhang, Shun-rong; Zhang, Qing-he; Liu, Jun-ming; Honary, F.

    2013-12-01

    Arctic ionospheric variations during the main phase of a magnetic storm on 14-15 December, 2006 were investigated to characterize the high energy particle precipitation caused effects, based on multi-instrument observations. These include electron density observations provided by the Global Positioning System (GPS) total electron content (TEC) measurements, European Incoherent Scatter (EISCAT) radar, the radio occultation (RO) from both the CHAMP satellite and the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite, as well as the ionospheric absorption of cosmic radio noise measured by the Imaging Riometer for Ionospheric Studies (IRIS) at Kilpisjärvi in the northern Finland (69.05°N, 20.79°E). Significant increases in the electron density for these different observations were found in the Arctic ionosphere during the main phase of the magnetic storm. These increase occurred in Scandinavian, Northwest part of Russia and Svalbard (SNRS) region, primarily at an altitude of about 110 km. These results are first reported for the SNRS region, and our study contributes to a more complete description of this space weather event during 14-15 December, 2006. Our observations also provide direct evidence that the stormtime E-layer electron density enhancement (e.g., the sporadic E) can form a nearly dominant portion in the observed TEC increase. These increases were accompanied by the ionospheric absorption enhancement at the altitude of about 90 km. The Y-component of magnetic field to the south of SNRS decreased, indicating strong upward field aligned electric current in the Arctic ionosphere. These features are interpreted as the effect of the high energy electron precipitation during the magnetic storm, which is caused by the sub-storm reflected on AL index and the measurements of IMAGE (International Monitor for Auroral Geomagnetic Effects) chain. The average energy of the precipitation electrons reached to about 10 keV and the

  5. Annual and semiannual variations of the geomagnetic field at equatorial locations

    NASA Astrophysics Data System (ADS)

    Campbell, W. H.

    1981-06-01

    The annual and semiannual variations of the quiet-sun year (1965) geomagnetic field are examined using geomagnetic records obtained from observatories located between about 0 and 30 deg N geomagnetic latitude. Three separate contributions are analyzed: (1) the quiet-day midnight level (MDT), (2) the solar-quiet daily variation (Sq), and (3) the quiet-time lunar semidiurnal tidal variation (L). Methods of three recent studies (Campbell, 1980a, 1980b) are used to emphasize the equatorial features, and the differences in the seasonal amplitude and phase changes, obtained from a Fourier analysis of annual and semiannual components in the three orthogonal magnetic-field directions, are illustrated. Conclusions are presented, including: (1) the equatorial MDT variations of the northward and vertical components at quiet periods seem to represent the expected seasonal nighttime magnetospheric distortions, (2) the seasonal equatorial region Sq follows closely the annual and semiannual patterns expected to be caused by ionospheric conductivity and heating variations that give rise to a dynamo current at E-region heights, and (3) the lunar seasonal variations show characteristics of dayside ionospheric electrojet origin.

  6. Total electron content of the ionosphere at two stations in East Africa during the 24-25 October 2011 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    D'ujanga, F. M.; Baki, P.; Olwendo, J. O.; Twinamasiko, B. F.

    2013-03-01

    The equatorial ionosphere has been known to become highly disturbed and thus rendering space-based navigation unreliable during space weather events, such as geomagnetic storms. Modern navigation systems, such as the Global Positioning System (GPS) use radio-wave signals that reflect from or propagate through the ionosphere as a means of determining range or distance. Such systems are vulnerable to effects caused by geomagnetic storms, and their performance can be severely degraded. This paper analyses total electron content (TEC) and the corresponding GPS scintillations using two GPS SCINDA receivers located at Makerere University, Uganda (Lat: 0.3o N; Lon: 32.5o E) and at the University of Nairobi, Kenya (Lat: 1.3o S; Lon: 36.8o E), both in East Africa. The analysis shows that the scintillations actually correspond to plasma bubbles. The occurrence of plasma bubbles at one station was correlated with those at the other station by using observations from the same satellite. It was noted that some bubbles develop at one station and presumably "die off" before reaching the other station. The paper also discusses the effects of the geomagnetic storm of the 24-25 October 2011 on the ionospheric TEC at the two East African stations. Reductions in the diurnal TEC at the two stations during the period of the storm were observed and the TEC depletions observed during that period showed much deeper depletions than on the non-storm days. The effects during the storm have been attributed to the uplift of the ionospheric plasma, which was then transported away from this region by diffusion along magnetic field lines.

  7. Impact of geomagnetic storm on fine and global structures of the ionosphere

    NASA Astrophysics Data System (ADS)

    Przepiorka, D.; Gromadzki, M.; Grzesiak, M.; Slominska, E.; Rothkaehl, H.; Space Plasma Group

    2011-12-01

    We have analyzed Demeter micro-satellite data, in particular from ISL, IAP and ICE experiments to study 3 magnetic storm events on January 2005: 7-8, 17-19 and 21-22. The most direct impact on ionosphere is situated at auroral zone but it also affects the dynamics of the ionosphere-thermosphere system at lower latitudes. In effect one can observe changes in the plasma parameters on the global scale. In this study we have analyzed plasma processes related to magnetic storm events and their impact on large scale ionospheric structures such as ionospheric trough. The aim of this study was to establish relation between large scale plasma inhomogeneities and small scale processes. We have produced diurnal global maps for electron density and temperature, ion temperature and ion concentrations. We also analyzed dynamics of the electric field distribution at ULF, ELF, VLF frequency ranges.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  10. Geomagnetic superchrons and time variations in the cooling rate of the core

    NASA Astrophysics Data System (ADS)

    Olson, P.

    2015-12-01

    Polarity reversal systematics from numerical dynamos are used to explore the relationship between geomagnetic reversal frequency, including geomagnetic superchrons, and time variations in the rate of the cooling of the core. We develop a parameterization of the average reversal frequency from numerical dynamos in terms of the core heat flux normalized by the difference between the present-day core heat flux and the core heat flux at geomagnetic superchron onset. A low-order polynomial fit of this parameterization to the 0-300 Ma Geomagnetic Polarity Time Scale (GPTS) reveals that a decrease in core heat flux relative to present-day of approximately 30% can account for the Cretaceous Normal Polarity and Kiaman Reversed Polarity Superchrons, whereas the hyper-reversing periods in the Jurassic GPTS imply a core heat flux approximately 20% higher than at present-day. Low heat flux and slow cooling of the core inferred during the Kiaman Reversed Polarity Superchron is qualitatively consistent with predictions from mantle global circulation models (mantle GCMs) that show a reduction in mantle convective activity during the time of Pangea, whereas these same mantle GCMs and most plate motion reconstructions predict fast core cooling during the Cretaceous Normal Polarity Superchron, suggesting that the cooling rate of the core is not generally in phase with variations in plate motions.

  11. Spectral characteristics of geomagnetic field variations at low and equatorial latitudes

    USGS Publications Warehouse

    Campbell, W.H.

    1977-01-01

    Geomagnetic field spectra from eight standard observations at geomagnetic latitudes below 30?? were studied to determine the field characteristics unique to the equatorial region. Emphasis was placed upon those variations having periods between 5 min and 4 hr for a selection of magnetically quiet, average, and active days in 1965. The power spectral density at the equator was about ten times that the near 30?? latitude. The initial manifestation of the equatorial electrojet as evidenced by the east-west alignment of the horizontal field or the change in vertical amplitudes occurred below about 20?? latitude. Induced current effects upon the vertical component from which the Earth conductivity might be inferred could best be obtained at times and latitudes unaffected by the electrojet current. Values of about 1.6 ?? 103 mhos/m for an effective skin depth of 500-600 km were determined. The spectral amplitudes increased linearly with geomagnetic activity index, Ap. The spectral slope had a similar behavior at all latitudes. The slope changed systematically with Ap-index and showed a diurnal variation, centered on local noon, that changed form with geomagnetic activity.

  12. Multiday thermospheric density oscillations associated with variations in solar radiation and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Xu, Jiyao; Wang, Wenbin; Zhang, Shunrong; Liu, Xiao; Yuan, Wei

    2015-05-01

    Thermospheric densities observed by Challenging Minisatellite Payload and Gravity Recovery and Climate Experiment satellites during 2002-2010 and the globally averaged thermospheric densities from 1967 to 2007 have been used to investigate latitudinal, longitudinal, and height dependences of the multiday oscillations of thermospheric densities. The data show that the main multiday oscillations in thermospheric densities are 27, 13.5, 9, and 7 day oscillations. The high-correlation coefficients between the density oscillations and the F10.7 or Ap index indicate that these oscillations are externally driven. The 27 day density oscillation, being the strongest, is induced by variations in solar radiation, as well as recurrent geomagnetic activity that is the result of corotating interaction regions (CIRs) and high-speed solar wind streams of coronal hole origin. Density oscillations at periods of 13.5, 9, and 7 days at solar minimum and during the declining phase are stronger than those at solar maximum. These oscillations are mainly associated with recurrent geomagnetic activity due to coronal hole high-speed streams and CIRs. The multiday, periodic oscillations of thermospheric density exhibit strong latitudinal and longitudinal variations in the geomagnetic coordinate and oscillate synchronously at different heights. Oscillations with zonal wave number 0 oscillate globally, whereas those with nonzero wave numbers are strong at high geomagnetic latitudes, and hemispherically asymmetric. They are stronger in the Southern Hemisphere. The spectral distributions of thermospheric densities at different heights have almost the same latitude and longitude structures, but the spectral magnitudes increase with height.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. A model providing long-term data sets of energetic electron precipitation during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Kamp, M.; Seppälä, A.; Clilverd, M. A.; Rodger, C. J.; Verronen, P. T.; Whittaker, I. C.

    2016-10-01

    The influence of solar variability on the polar atmosphere and climate due to energetic electron precipitation (EEP) has remained an open question largely due to lack of a long-term EEP forcing data set that could be used in chemistry-climate models. Motivated by this, we have developed a model for 30-1000 keV radiation belt driven EEP. The model is based on precipitation data from low Earth orbiting POES satellites in the period 2002-2012 and empirically described plasmasphere structure, which are both scaled to a geomagnetic index. This geomagnetic index is the only input of the model and can be either Dst or Ap. Because of this, the model can be used to calculate the energy-flux spectrum of precipitating electrons from 1957 (Dst) or 1932 (Ap) onward, with a time resolution of 1 day. Results from the model compare well with EEP observations over the period of 2002-2012. Using the model avoids the challenges found in measured data sets concerning proton contamination. As demonstrated, the model results can be used to produce the first ever >80 year long atmospheric ionization rate data set for radiation belt EEP. The impact of precipitation in this energy range is mainly seen at altitudes 70-110 km. The ionization rate data set, which is available for the scientific community, will enable simulations of EEP impacts on the atmosphere and climate with realistic EEP variability. Due to limitations in this first version of the model, the results most likely represent an underestimation of the total EEP effect.

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

    NASA Technical Reports Server (NTRS)

    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. Spatial Variation in Storm Surge in the Strait of Georgia

    NASA Astrophysics Data System (ADS)

    Soontiens, N. K.; Allen, S. E.; Latornell, D.; Le Souef, K.; Machuca, I.

    2014-12-01

    The Strait of Georgia is a strongly stratified, deep body of water located between Vancouver Island and the mainland of British Columbia and is connected to the Pacific Ocean via the Strait of Juan de Fuca to the south and Johnstone Strait to the north. It is on average 220 km in length and 30 km wide and its maximum depth is 420 m. During the winter months, coastal communities in the Strait of Georgia are at risk to flooding caused by storm surges, a natural hazard that occurs when a strong wind storm with low atmospheric pressure coincides with an unusually high tide. This study presents storm surge hindcasts of significant events between 2006 and 2009 using a numerical model of the Straits of Georgia, Juan de Fuca, Johnstone and Puget Sound (together the Salish Sea). The model is based on the Nucleus for European Modelling of the Ocean (NEMO) in a regional configuration. Realistic stratification is produced by including input from the surrounding rivers. A discussion on the sensitivity of modelled surge amplitude to open boundary conditions and atmospheric forcing will be presented. As barotropic models have previously shown, the surge entering the domain from the Pacific Ocean contributes most significantly. Surge amplitudes are found to be greater within the Strait of Georgia than those in the Strait of Juan de Fuca. Local wind patterns cause spatial variations in the strength of the surge in the Strait of Georgia, generally leading to stronger surges on the Mainland side of the Strait.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Transport of Energetic Ions in the Ring Current During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Kistler, Lynn M.; Kaufmann, Richard

    2001-01-01

    In the final year (plus no-cost extentions) of this grant, we have: Used the particle tracing code to perform a systematic study of the expected energy spectra over the full range of local times in the ring current using a variety of electric and magnetic field models. Shown that the Weimer electric field is superior to the Volland-Stern electric field in reproducing the observed energy spectra on the AMPTE CCE spacecraft. Redone our analysis of the pitch angle spectra of energetic ions during storms in the magnetosphere, using a larger data set, and a more reliable classification technique.

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

    NASA Astrophysics Data System (ADS)

    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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

  2. Contrasting behavior of the F2 peak and the topside ionosphere in response to the 2 October 2013 geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Lei, Jiuhou; Zhong, Jiahao; Mao, Tian; Hu, Lianhuan; Yu, Tao; Luan, Xiaoli; Dou, Xiankang; Sutton, Eric; Yue, Xinan; Lin, Jian; Batista, Inez S.

    2016-10-01

    In this study, the ionospheric observations from ionosondes, ground-based GPS receivers, Gravity Recovery and Climate Experiment (GRACE) and MetOp-A satellites, and Fabry-Perot interferometer over the Asian-Australian sector have been used to investigate the responses of the F2 peak and the topside ionosphere to the 2 October 2013 geomagnetic storm, particularly during the recovery phase. The comparison between the multiple simultaneous observations revealed a contrasting behavior of the topside ionosphere and the F2 peak in East Asia during the recovery phase. The upward looking total electron content from low-Earth orbit (LEO) satellites did not undergo such depletions as seen in the region near the F2 peak, and they even showed increases. Furthermore, the simulation results of the Thermosphere Ionosphere Electrodynamics General Circulation Model are used to explore the possible mechanisms responsible for the observed features. The model results and observations suggested that the contrasting behavior of the F2 peak and the topside ionosphere is mainly associated with the enhancement of the equatorward winds, albeit the disturbed electric fields could play an important role in producing it.

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

    NASA Astrophysics Data System (ADS)

    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. Statistical analysis of geomagnetic field variations during the partial solar eclipse on 2011 January 4 in Turkey

    NASA Astrophysics Data System (ADS)

    Ateş, Abdullah; Ekinci, Yunus Levent; Buyuksarac, Aydin; Aydemir, Attila; Demirci, Alper

    2015-05-01

    Some geophysical parameters, such as those related to gravitation and the geomagnetic field, could change during solar eclipses. In order to observe geomagnetic fluctuations, geomagnetic measurements were carried out in a limited time frame during the partial solar eclipse that occurred on 2011 January 4 and was observed in Canakkale and Ankara, Turkey. Additionally, records of the geomagnetic field spanning 24 hours, obtained from another observatory (in Iznik, Turkey), were also analyzed to check for any peculiar variations. In the data processing stage, a polynomial fit, following the application of a running average routine, was applied to the geomagnetic field data sets. Geomagnetic field data sets indicated there was a characteristic decrease at the beginning of the solar eclipse and this decrease can be well-correlated with previous geomagnetic field measurements that were taken during the total solar eclipse that was observed in Turkey on 2006 March 29. The behavior of the geomagnetic field is also consistent with previous observations in the literature. As a result of these analyses, it can be suggested that eclipses can cause a shielding effect on the geomagnetic field of the Earth.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

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

    PubMed

    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.

  10. Geomagnetic response to solar activity.

    NASA Technical Reports Server (NTRS)

    Mead, G. D.

    1972-01-01

    The relationship between solar activity and geomagnetic variations is discussed in the light of spacecraft data obtained during the last decade. The effects of centers of solar activity responsible for producing geomagnetic activity on earth are believed to be transmitted through the solar wind, and there is usually a delay of two or three days before the onset of magnetic activity. Attempts to make a one-to-one correspondence between specific solar events and specific magnetic storms, however, are usually unsuccessful, because of the complex and indirect processes linking the two phenomena. Normally, only statistical tendencies can be shown.

  11. Annual and semiannual variations of the geomagnetic field at equatorial locations

    USGS Publications Warehouse

    Campbell, W.H.

    1981-01-01

    For a year of quiet solar-activity level, geomagnetic records from American hemisphere observatories located between about 0?? and 30?? north geomagnetic latitude were used to compare the annual and semiannual variations of the geomagnetic field associated with three separate contributions: (a) the quiet-day midnight level, MDT; (b) the solar-quiet daily variation, Sq; (c) the quiet-time lunar semidiurnal tidal variation, L(12). Four Fourier spectral constituents (24, 12, 8, 6 h periods) of Sq were individually treated. All three orthogonal elements (H, D and Z) were included in the study. The MDT changes show a dominant semiannual variation having a range of about 7 gammas in H and a dominant annual variation in Z having a range of over 8 gammas. These changes seem to be a seasonal response to the nightside distortions by magnetospheric currents. There is a slow decrease in MDT amplitudes with increasing latitude. The Sq changes follow the patterns expected from an equatorial ionospheric dynamo electrojet current system. The dominant seasonal variations occur in H having a range of over 21 gammas for the 24 h period and over 12 gammas for the 12 h period spectral components. The higher-order components are relatively smaller in size. The Sq(H) amplitudes decrease rapidly with increasing latitude. Magnetospheric contributions to the equatorial Sq must be less than a few per cent of the observed magnitude. The L(12) variation shows the ionospheric electrojet features by the dominance of H and the rapid decrease in amplitude with latitude away from the equator. However, the seasonal variation range of over 7 gammas has a maximum in early February and minimum in late June that is not presently explainable by the known ionospheric conductivity and tidal behavior. ?? 1981.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Compressional perturbations of the dayside magnetosphere during high-speed-stream-driven geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Borovsky, Joseph E.; Denton, Michael H.

    2016-05-01

    The quasi-DC compressions of the Earth's dayside magnetic field by ram-pressure fluctuations in the solar wind are characterized by using multiple GOES spacecraft in geosynchronous orbit, multiple Los Alamos spacecraft in geosynchronous orbit, global MHD simulations, and ACE and Wind solar wind measurements. Owing to the inward-outward advection of plasma as the dayside magnetic field is compressed, magnetic field compressions experienced by the plasma in the dayside magnetosphere are greater than the magnetic field compressions measured by a spacecraft. Theoretical calculations indicate that the plasma compression can be a factor of 2 higher than the observed magnetic field compression. The solar wind ram-pressure changes causing the quasi-DC magnetospheric compressions are mostly owed to rapid changes in the solar wind number density associated with the crossing of plasma boundaries; an Earth crossing of a plasma boundary produces a sudden change in the dayside magnetic field strength accompanied by a sudden inward or outward motion of the plasma in the dayside magnetosphere. Superposed epoch analysis of high-speed-stream-driven storms was used to explore solar wind compressions and storm time geosynchronous magnetic field compressions, which are of particular interest for the possible contribution to the energization of the outer electron radiation belt. The occurrence distributions of dayside magnetic field compressions, solar wind ram-pressure changes, and dayside radial plasma flow velocities were investigated: all three quantities approximately obey power law statistics for large values. The approximate power law indices for the distributions of magnetic compressions and ram-pressure changes were both -3.

  14. Long-term variation in the ionosphere and lower thermosphere as seen in the geomagnetic solar quiet daily variation

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    In order to investigate characteristics of the long-term variation in the ionosphere and lower thermosphere, we analyzed the amplitude of geomagnetic solar quiet (Sq) field daily variation using 1-h geomagnetic field data obtained from 69 geomagnetic stations within the period of 1947-2013. In the present data analysis, we took advantage of the Inter-university Upper atmosphere Global Observation NETwork (IUGONET) products (metadata database and analysis software) for finding and handling the long-term observation data obtained at many observatories. The Sq amplitude observed at these geomagnetic stations showed a clear solar activity dependence and tended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle 23/24 in 2008-2009. This significant depression implies that the solar extreme ultraviolet (EUV) radiation responsible for ionization of the upper atmosphere decreased during this solar cycle minimum. In order to examine a global distribution of the long-term trend in the Sq amplitude, we derived the residual Sq amplitude from the deviation from the fitting curve between the solar F10.7 index and Sq amplitude. As a result, a majority of the trends in the residual Sq amplitude showed negative values over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. Moreover, we estimate the neutral wind in the lower thermosphere from the Sq amplitude and height-integrated ionospheric conductivity in order to know the physical mechanism of the long-term trend in the residual Sq amplitude. As a result, the estimated thermospheric zonal and meridional winds showed a seasonal variation with a period of one year or less, but the solar activity dependence was unclear. This result suggests that the solar cycle dependence of the Sq amplitude may be mainly attributed to the variation of the ionospheric conductivity.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  16. The Identification of Seismo and Volcanomagnetic Events Using Non-stationary Analysis of Geomagnetic Field Variations.

    NASA Astrophysics Data System (ADS)

    Fedi, M.; Gonçalves, P.; Johnston, M.; La Manna, M.

    Many studies have shown a clear correlation between volcanic and/or seismic activ- ity and time variations of local geomagnetic fields, called seismomagnetic (SM) and /or volcanomagnetic (VM) effects. SM and VM can be generated from various phys- ical process, such as piezomagnetism, tectonomagnetism and electrokinetism. Rele- vant parameters are the event duration, the event magnitude and the magnetometer sample rate. Here, we present some results obtained from a non-stationary analysis of geomagnetic time series that focuses on automatic detection of possible SM and VM events. Several approaches are considered. The first one, based on the continuous wavelet transform, provides us with a multiresolution lecture of the signal, expanded in time-scale space. The second uses a time-variant adaptive algorithm (RLS) that al- lows the detection of some time intervals where important statistical variations of the signal occur. Finally, we investigate a third technique relying on multifractal analy- sis. This latter allows estimation of local regularity of a time series path, in order to detect unusual singularities. Different multifractal models were used for testing the methodology, such as multifractional Brownian Motions (mbmSs), before applying it to synthetic simulations of geomagnetic signals. In our simulations, we took into account theoretical SM and/or VM effects deriving from fault rupture and overpres- sured magma chambers. We applied these methodologies to two different real world data sets, recorded on Mt Etna (volcanic area) during the volcanic activity occurred in 1981, and in North Palm Springs (seismic area) during the seism of July 8th 1986, respectively. In both cases, all techniques were effective in automatically identifying the geomagnetic time-variations likely inferred by volcanic and/or seismic activity and the results are in good agreement with the indices provided by real volcanic and seismic measurements.

  17. The Identification of Seismo and Volcanomagnetic Events Using Non-stationary Analysis of Geomagnetic Field Variations.

    NASA Astrophysics Data System (ADS)

    Fedi, M.; Gonçalves, P.; Johnston, M.; La Manna, M.

    Many studies have shown a clear correlation between volcanic and/or seismic activ- ity and time variations of local geomagnetic fields, called seismomagnetic (SM) and /or volcanomagnetic (VM) effects. SM and VM can be generated from various phys- ical process, such as piezomagnetism, tectonomagnetism and electrokinetism. Rele- vant parameters are the event duration, the event magnitude and the magnetometer sample rate. Here, we present some results obtained from a non-stationary analysis of geomagnetic time series that focuses on automatic detection of possible SM and VM events. Several approaches are considered. The first one, based on the continuous wavelet transform, provides us with a multiresolution lecture of the signal, expanded in time-scale space. The second uses a time-variant adaptive algorithm (RLS) that al- lows the detection of some time intervals where important statistical variations of the signal occur. Finally, we investigate a third technique relying on multifractal analy- sis. This latter allows estimation of local regularity of a time series path, in order to detect unusual singularities. Different multifractal models were used for testing the methodology, such as multifractional Brownian Motions (mbm 's), before applying it to synthetic simulations of geomagnetic signals. In our simulations, we took into account theoretical SM and/or VM effects deriving from fault rupture and overpres- sured magma chambers. We applied these methodologies to two different real world data sets, recorded on Mt Etna (volcanic area) during the volcanic activity occurred in 1981, and in North Palm Springs (seismic area) during the seism of July 8th 1986, respectively. In both cases, all techniques were effective in automatically identifying the geomagnetic time-variations likely inferred by volcanic and/or seismic activity in fact we obtained results in good agreement with the indices provided by real volcanic and seismic measurements.

  18. Geomagnetic Field Response at Southern and Northern Hemisphere

    NASA Astrophysics Data System (ADS)

    Chandel, Babita

    Geomagnetic Field Response at Southern and Northern Hemisphere Babita Chandel, Shailendra Saini, Sneha Yadav,S.K.Vijay and A.K.Gwal Space Science Laboratory, Department of Physics, Barkatullah University, Bhopal-462026, India ABSTRACT: This paper represents the geomagnetic field response at Southern Hemisphere (MAITRI) and Northern Hemisphere (TROMSO). The Indian Antarctic Station MAITRI is located at geomagnetic Long. (66.030, 53.210) where as TROMSO is at geomagnetic Long. (66.030, 53.210). We studied the behaviour of geomagnetic field with respect to geomagnetic storms at both the stations TROMSO and MAITRI. It was observed that at Southern Hemisphere there is more variation in winter as compared to the summer season, where as in Northern Hemisphere the variations are more in summer as compared to winter. As in the Northern hemisphere the magnetospheric plasma is strongly turbulized in summer and in Southern hemisphere the magentospheric plasma is strongly turbulized in winter.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Multispacecraft Observations and Modeling of the 22/23 June 2015 Geomagnetic Storm

    NASA Technical Reports Server (NTRS)

    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.

    2016-01-01

    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.

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

    PubMed

    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.

  2. Daily variations of geomagnetic H D and Z-field at equatorial latitudes

    NASA Astrophysics Data System (ADS)

    Okeke, F. N.; Hamano, Y.

    2000-04-01

    With the establishment of the new geomagnetic field observations in the Ocean Hemisphere Network Project (OHP) in Japan, minutes values of geomagnetic components, H D and Zhave been recorded. The hourly mean values were used to study the variations in these three components at these new equatorial electrojet regions. The results of the analysis carried out revealed that the amplitude of dHhas diurnal variation which peaks during the day at about local noon in all the three equatorial electrojet regions. This diurnal variation in Hwith Sq(H) enhancement in all the three regions are attributed to the enhanced dynamo action at these regions. Diurnal variation as observed in Dindicates that the equatorial electrojet current system has both east-west and north-south components. The pronounced magnitude of Zvariation as observed in Kiritimati is attributed mainly to sea induction. Also some abnormal features were observed on 23rd of January at Huancayo, in the components. Seasonal variations with more pronounced equinoctial maximum were observed in Hthan in Z. Dcomponent showed no consistent seasonal variation in all the regions. The equinoctial maximum is due to enhanced equatorial electron density at equinox. More research work, if carried out in these new regions will be useful in making more new contributions to the field of the dynamics of the equatorial electrojet region.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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 (<1 au). On 2012 June 12-16, three approximately Earthward-directed and interacting CMEs were observed by the Solar Terrestrial Relations Observatory imagers and Venus Express (VEX) in situ at 0.72 au, 6° away from the Sun-Earth line. The CME kinematics are calculated using the drag-based and WSA-Enlil models, constrained by the arrival time at VEX, resulting in the CME arrival time and speed on Earth. The CME magnetic field strength is scaled with a power law from VEX to Wind. Our investigation shows promising results for the Dst forecast (predicted: -96 and -114 nT (from 2 Dst models); observed: -71 nT), for the arrival speed (predicted: 531 ± 23 km s-1 observed: 488 ± 30 km s-1), and for the timing (6 ± 1 hr after the actual arrival time). The prediction lead time is 21 hr. The method may be applied to 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.

  5. Large Enhancements in the O/N2 Ratio in the Evening Sector of the Winter Hemisphere During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Burns, A. G.; Killeen, T. L.; Carignan, G. R.; Roble, R. G.

    1995-01-01

    In this paper, we have looked for enhancements of the O/N2 ratio in data measured by the Dynamics Explorer 2 (DE 2) satellite in the middle latitudes of the winter hemisphere, based on a prediction that was made by the National Center for Atmospheric Research thermosphere/tonosphere general circulation model (NCAR-TIGCM) that such increases occur. The NCAR-TIGCM predicts that these enhancements should be seen throughout the low latitude region and in many middle latitude locations, but that the enhancements in O/N2 are particularly strong in the middle-latitude, evening-to-midnight sector of the winter hemisphere. When this prediction was used to look for these effects in DE 2 NACS (neutral atmosphere composition spectrometer) data, large enhancements in the O/N2 ratio (approx. 50 to 90%) were seen. These enhancements were observed during the main phase of a storm that occurred on November 24, 1982, and were seen in the same region of the winter hemisphere predicted by the NCAR-TIGCM. They are partially the result of the depletion of N2 and, as electron loss is dependent on dissociative recombination at F(sub 2) altitudes, they have implications for electron densities in this area. Parcel trajectories, which have been followed through the NCAR-TIGCM history file for this event, show that large O/N2 enhancements occur in this limited region in the winter hemisphere for two reasons. First, these parcels of air are decelerated by the antisunward edge of the ion convection pattern; individual parcels converge and subsidence occurs. Thus molecular-nitrogen-poor air is brought from higher to lower heights. Because neutral parcels that are found a little poleward of the equatorial edge of the eveningside convection pattern are swept inward toward the center of the auroral oval, the enhancements occur only in a very limited range of latitudes. Second, nitrogen-poor air is transported from regions close to the magnetic pole in the winter hemisphere. During geomagnetic

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

    NASA Astrophysics Data System (ADS)

    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

  7. Response of the Fair Weather Atmospheric Electrical Current to Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Yair, Yoav; Price, Colin; Elhalal, Gal

    2013-04-01

    The Global Electric Circuit (GEC) is a conceptual model that integrates the observed electrical properties of the atmosphere in the Earth-ionosphere cavity. An average potential difference of 250 kV exists between these two conducting layers, leading to a surface electric field (Ez, sometimes also named the Potential Gradient or PG) of ~130 V/m, and a nearly constant downward flowing direct current density (Jz) of ~2 pA m-2. This is known as the DC component of the GEC. The Jz is an extremely sensitive parameter whose magnitude and fluctuations can be used for monitoring local and global conductivity changes due to aerosols, air-pollution and solar activity. The AC part of the circuit is driven by ~50 lightning flashes per second generating the global Schumann resonances (SR) in the ELF range. There are two time-scales for identifying solar effects on the GEC. On the longer scale, an 11-year modulation by solar activity, likely due to changes in ionization, was reported by several authors. For example, Satori et al. (2005) noted a decrease in the frequency of the first 3 modes of the SR band in conjunction with the solar minimum of 1995-6. On shorter time scales typical of solar activity (e.g. CMEs, solar flares and SEP events), observations show marked perturbations in Jz and in the ionospheric potential at the surface. Cobb (1967) observed an increase of Jz by 75% for ~ 6 h in measurements made at Mauna Loa in Hawaii, during a period of multiple solar flares. Reiter (1989) observed an increase in Jz of about 50%-60% following large solar flares, persisting for 4 days (at the Zungspietze station in the Alps). Belova et al. (2001) reported increased Jz for about 2 hours before T=0 (time of minimum in Bx) as well as enhanced average fluctuations. This talk will review the effects of solar storms on the GEC, and present new results from continuous measurements of Jz conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30°35'N, 34°45'E). During 3 different

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

    NASA Astrophysics Data System (ADS)

    Biktash, Lilia

    2016-07-01

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

  9. Statistics of the geomagnetic secular variation for the past 5Ma

    NASA Technical Reports Server (NTRS)

    Constable, C. G.; Parker, R. L.

    1986-01-01

    A new statistical model is proposed for the geomagnetic secular variation over the past 5Ma. Unlike previous models, the model makes use of statistical characteristics of the present day geomagnetic field. The spatial power spectrum of the non-dipole field is consistent with a white source near the core-mantle boundary with Gaussian distribution. After a suitable scaling, the spherical harmonic coefficients may be regarded as statistical samples from a single giant Gaussian process; this is the model of the non-dipole field. The model can be combined with an arbitrary statistical description of the dipole and probability density functions and cumulative distribution functions can be computed for declination and inclination that would be observed at any site on Earth's surface. Global paleomagnetic data spanning the past 5Ma are used to constrain the statistics of the dipole part of the field. A simple model is found to be consistent with the available data. An advantage of specifying the model in terms of the spherical harmonic coefficients is that it is a complete statistical description of the geomagnetic field, enabling us to test specific properties for a general description. Both intensity and directional data distributions may be tested to see if they satisfy the expected model distributions.

  10. Geomagnetic variations possibly associated with the Pisco earthquake on 15 August 2007, Peru

    NASA Astrophysics Data System (ADS)

    Takla, E. M.; Yumoto, K.; Ishitsuka, J.; Rosales, D.; Dutra, S.; Uozumi, T.; Abe, S.

    2012-02-01

    On 15 August 2007, Pisco earthquake (magnitude 8.0) hit the central coast of Peru near the MAGDAS Ancon (ANC) station. Geomagnetic data from ANC and other reference stations have been analyzed to detect any signature related to this great earthquake. Results indicate the presence of annual geomagnetic variations in the vertical component at ANC and Huancayo (HUA) stations (in the vicinity of the epicenter of Pisco earthquake). These variations have a quasi-sinusoidal waveform with amplitudes of about 10 and 5 nT for ANC and HUA stations respectively. They appeared clearly during the period preceding the onset of the Pisco earthquake especially at ANC station. By using HUA, Eusebio (EUS) and Kourou (KOU) as reference stations in the vicinity and away from the epicenter of Pisco earthquake, a clear disappearance of the diurnal variation of the vertical component was observed at ANC station during the day of earthquake. Moreover, the Pisco earthquake and another earthquake (on 29 March 2008) near ANC station were found to occur concurrently with the depressions in the polarization ratio (Z/H) of Pc 3 (10-45 s) amplitude. Such anomalous variations appear to be a result of changes in the crustal stress field and the lithospheric conductivity in the studied region.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Response of the Midlatitude F2 Layer to Some Strong Geomagnetic Storms during Solar Minimum as Observed at Four Sites of the Globe

    NASA Astrophysics Data System (ADS)

    Kim, Vitaly P.; Hegai, Valery V.

    2015-12-01

    In this study, we documented the midlatitude F2-layer response to five strong geomagnetic storms with minimum Dst < -150 nT that occurred in solar minimum years using hourly values of the F2-layer critical frequency (foF2) from four ionosondes located in different hemispheres. The results were very limited, but they illustrated some peculiarities in the behavior of the F2-layer storm. During equinox, the characteristic ionospheric disturbance patterns over the Japanese station Wakkanai in the Northern Hemisphere and the Australian station Mundaring in the Southern Hemisphere were consistent with the well-known scenario by Prölss (1993); however, during a December solstice magnetic storm, both stations did not observe any noticeable positive ionospheric disturbances. Over the "near-pole" European ionosonde, clear positive ionospheric storms were not observed during the events, but the "far-from-pole" Southern Hemisphere station Port Stanley showed prominent enhancements in F2-layer peak electron density in all magnetic storms except one. No event produced noticeable nighttime enhancements in foF2 over all four ionosondes.

  13. Storm-time changes of geomagnetic field at MAGSAT altitudes (325-550 Km) and their comparison with changes at ground locations

    NASA Technical Reports Server (NTRS)

    Parada, N. D. J. (Principal Investigator); Kane, R. P.; Trivedi, N. B.

    1983-01-01

    The values of H, X, Y, Z at MAGSAT altitudes were first expressed as residuals delta H, delta X, delta Y, delta Z after subtracting the model HMD, XMD, YMD, ZMC. The storm-time variations of H showed that delta H (Dusk) was larger (negative) than delta H (Dawn) and occurred earlier, indicating a sort of hysteresis effect. Effects at MAGSAT altitudes were roughly the same (10% accuracy) as at ground, indicating that these effects were mostly of magnetospheric origin. The delta Y component also showed large storm-time changes. The latitudinal distribution of storm-time delta H showed north-south asymmetries varying in nature as the storm progressed. It seems that the central plane of the storm-time magnetospheric ring current undergoes latitudinal meanderings during the course of the storm.

  14. Properties of Alfven waves in the magnetotail below 9 R(E) and their relation to auroral acceleration and major geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Dombeck, John Paul

    The presented studies investigate the characteristics of Alfvén wave events in the geomagnetic tail on the plasma sheet boundary layer (PSBL) and possibly well within the plasma sheet during substorms and major geomagnetic storms (<- 200 Dst). Such storms are rare but dramatically affect the state of the magnetosphere in ways that we have only recently been capable of investigating with sufficient in situ instrumentation. The first comparative study of major storm PSBL Alfvén waves events is presented. Properties of eight substorm and ten major storm events are compared using a new method, providing new insights into the phenomena, their interactions in the auroral acceleration region (AAR), and their generation. Direct comparison between Polar and FAST indicating a decrease (increase) in low-(high-)frequency shear (kinetic) earthward Alfvénic Poynting flux and an increase in earthward electron energy flux strongly suggests transfer of shear Alfvén wave Poynting flux to kinetic Alfvén waves which then accelerate auroral electrons. Polar observations also suggest a broadband source and indicate that small-scale, temporally/spatially variable factors, likely including density cavities and ionospheric conductivity structure, strongly affect the reflectivity/dissipation properties, as the waves in each frequency band contain a mixture of earthward, tailward, reflecting and incoherent wave intervals. Averages of these properties are consistent with theory, but the detailed structure has not been predicted. Tailward intervals also suggest ionospheric field line shear. Most major storm events were found have similar properties to substorm events with a few notable differences, consistent with effects related to the extended duration of storms. Low-latitude broadband auroral electrons and high-frequency Alfvén waves along with properties of a unique Alfvén wave event, related to a major storm tail reconfiguration, with very intense Poynting flux and the first

  15. Source identification of moderate (-100 nT < Dst < -50 nT) and intense geomagnetic storms (Dst < -100 nT) during ascending phase of solar cycle 24

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    The origin of 39 moderate (-100 nT < Dst < -50 nT) and 12 intense (Dst < -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.

  16. A correlation between measured E-region current and geomagnetic daily variation at equatorial latitude

    NASA Astrophysics Data System (ADS)

    Duhau, S.; Osella, A. M.

    The usual methods of separation of the geomagnetic daily variations into parts of external and internal origin at equatorial latitudes have been revised to remove any previous assumption about the internal current, so that the separation may be performed in a zone of anomalous earth conductivity. The resulting procedure has been applied to obtain the distribution of the ionospheric current from the external field, at the South American dip equator and the result has been compared with previous measurements of the E-region current.

  17. Do Geomagnetic Variations Affect the Foliar Spiral Direction of Coconut Palms?

    NASA Astrophysics Data System (ADS)

    Minorsky, P. V.; Bronstein, N. B.

    2005-12-01

    In coconut palms, leaves are attached to the stem in either an ascending clockwise (left-handed or L) or counter-clockwise (right-handed or R) spiral (1). Foliar spiral direction (FSD) is a classic case of morphological antisymmetry, in which dextral and sinistral forms are not inherited and are equally common within a species (2). FSD would seem a simple stochastic process unworthy of further study if not for the observation, based on data collected from 71,640 coconut palms in 42 locations around the world, that the FSD of coconut palms varies with latitude: R-trees predominate in the N Hemisphere and L-trees predominate in the S Hemisphere (3). Hemispheric asymmetries in FSD are significantly better correlated with magnetic latitude than with geographic or geomagnetic latitude, suggesting that latitudinal asymmetries in FSD might be associated with the temporally varying component of Earth's magnetic field (4). Here, we present two new lines of evidence that geomagnetic variations may underlie asymmetries in palm FSD. First, we show that asymmetries occur in the FSD of palm populations on opposite sides of islands, and second, that asymmetries in FSD vary with the 11-year solar cycle. The prediction that asymmetries in coconut palm FSD should exist on opposite sides of islands arises from the fact that because seawater is more electrically conductive than land, induced earth currents divide and stream past an island more strongly in one particular direction. The "geomagnetic island effect" is characterized by a complete reversal of the vertical Z component of short-period geomagnetic field anomalies at observation points on opposite sides of islands (5). To examine whether FSD varied around the circumferences of islands, we collected data on 6 islands (Puerto Rico, n = 4311; Antigua, n = 2038; Hawaii, n = 3552; Maui, n = 2175; Tahiti, n = 1582; Moorea, n = 2116). For each population, the degree of asymmetry was determined by calculating an "asymmetry quotient

  18. TEC Variations Over Korean Peninsula During Magnetic Storm

    NASA Astrophysics Data System (ADS)

    Ji, E.-Y.; Choi, B.-K.; Kim, K.-H.; Lee, D.-H.; Cho, J.-H.; Chung, J.-K.; Park, J.-U.

    2008-03-01

    By analyzing the observations from a number of ground- and space-based instruments, including ionosonde, magnetometers, and ACE interplanetary data, we examine the response of the ionospheric TEC over Korea during 2003 magnetic storms. We found that the variation of vertical TEC is correlated with the southward turning of the interplanetary magnetic field B_z. It is suggested that the electric fields produced by the dynamo process in the high-latitude region and the prompt penetration in the low-latitude region are responsible for TEC increases. During the June 16 event, dayside TEC values increase more than 15%. And the ionospheric F2-layer peak height (hmF2) was ˜300km higher and the vertical E×B drift (estimated from ground-based magnetometer equatorial electrojet delta H) showed downward drift, which may be due to the ionospheric disturbance dynamo electric field produced by the large amount of energy dissipation into high-latitude regions. In contr! ast, during November 20 event, the nightside TEC increases may be due to the prompt penetration westward electric field. The ionospheric F2-layer peak height was below 200km and the vertical E×B drift showed downward drift. Also, a strong correlation is observed between enhanced vertical TEC and enhanced interplanetary electric field. It is shown that, even though TEC increases are caused by the different processes, the electric field disturbances in the ionosphere play an important role in the variation of TEC over Korea.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Synchronous Variations of the Free Aquifer Groundwater Level and Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Ryabova, Svetlana A.; Spivak, Alexander A.

    2015-04-01

    We consider long period variations of the magnetic field at the Earth's crust surface and its relation to seasonal change of the groundwater regime at the middle latitude geophysical observatory "Mikhnevo", situated at 85 km south of Moscow. Observatory is located away from large industrial projects allowing one to realize correct recording of geophysical fields. Results of synchronous observations of geomagnetic variations and groundwater regime were used as basic data. Measurements of the local variations of the magnetic field were carried out in special geomagnetic pavilion using flux-gate magnetometer LEMI-018 (measurement range ±68 000 nT, resolution capacity 10 pT). Received digital data rows with discretization 1 s resulted in sequence of values in 1 min. Measurements of the groundwater variations in water-table aquifer were carried out in the well of 30 m depth using sensitive sensor of water level LMP308i (resolving capacity 0.1 mm). Magnetic tipper, which is very sensitive to changes of the Earth's crust properties, was considered as characteristics of the magnetic variations, and in the same time as an indicator of the change of the electric properties of the medium. Results of calculations demonstrate clear marked annual variation of both real and imaginary composites of magnetic tipper describing relation between vertical component of magnetizing force and its horizontal components. Increase of thickness of the layer of watered rock resulting from rise of underground water level in water-table aquifer causes an increase of electrical conductivity of subsurface Earth's crust plot. It results in synchronous magnetic tipper variations.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  4. RESEARCH NOTE: A Late Holocene geomagnetic secular variation record from Erhai Lake, southwest China

    NASA Astrophysics Data System (ADS)

    Hyodo, Masayuki; Yoshihara, Arata; Kashiwaya, Kenji; Okimura, Takashi; Masuzawa, Toshiyuki; Nomura, Ryotaro; Tanaka, Shingo; Xing, Tang Bang; Qing, Liu Su; Jian, Liu Shi

    1999-03-01

    A secular variation record of the geomagnetic field direction for the last 6.5 kyr has been obtained from the magnetization of sediment cores from Erhai Lake, southwest China. In order to make a comparison with this record, secular variation in east-central China was investigated by combining available magnetic field data from historical records and archaeomagnetic measurements since about 350 bc. The secular variation in Erhai Lake shows features consistent with the combined record, except for the oldest three observed declination swings in Sian from 720 to 900 ad. Many features of declination and inclination in China also occur in Japan. From 500 to 1000 ad, declination was westerly ranging from about -20° to -5° in Erhai Lake, east-central China, and Japan.

  5. Reconstruction of the long term variations of the total solar irradiance from geomagnetic data

    NASA Astrophysics Data System (ADS)

    Georgieva, K.; Nagovitsyn, Yu.; Kirov, B.

    2015-12-01

    The total solar irradiance (TSI) is considered one of the main factors determining the terrestrial climate, and its variations are included in many numerical models evaluating the effects of natural as compared to anthropogenic factors of climate change. For the purposes of climate change, it is important to estimate both past and future TSI variations, which are caused by variations of the solar magnetic fields. Various proxies are used for reconstructing the long term evolution of TSI, which have some inevitable limitations leading to big uncertainties. We suggest an independent proxy-geomagnetic activity records, and present a reconstruction of TSI which supports higher long term TSI variability than generally accepted, and a prediction for a decrease in TSI in the following cycles, which can be taken into account in models of the expected future climate variability.

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

    NASA Technical Reports Server (NTRS)

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  10. 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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Cherniak, Iurii; Zakharenkova, Irina

    2015-09-01

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

  12. 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

    SciTech Connect

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

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  15. Long periods (1 -10 mHz) geomagnetic pulsations variation with solar cycle in South Atlantic Magnetic Anomaly

    NASA Astrophysics Data System (ADS)

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

    The occurrence and intensity of the geomagnetic pulsations Pc-5 (2-7 mHz) and its relationship with the solar cycle in the South Atlantic Magnetic Anomaly -SAMA is presented. The study of geomagnetic pulsations is important to help the understanding of the physical processes that occurs in the magnetosphere region and help to predict geomagnetic storms. The fluxgate mag-netometers H, D and Z, three axis geomagnetic field data from the Southern Space Observatory -SSO/CRS/INPE -MCT, São Martinho da Serra (29.42° S, 53.87° W, 480m a.s.l.), RS, Brasil, a were analyzed and correlated with the solar wind parameters (speed, density and temperature) from the ACE and SOHO satellites. A digital filtering to enhance the 2-7 mHz geomagnetic pulsations was used. Five quiet days and five perturbed days in the solar minimum and in the solar maximum were selected for this analysis. The days were chosen based on the IAGA definition and on the Bartels Musical Diagrams (Kp index) for 2001 (solar maximum) and 2008 (solar minimum). The biggest Pc-5 amplitude averages differences between the H-component is 78,35 nT for the perturbed days and 1,60nT for the quiet days during the solar maximum. For perturbed days the average amplitude during the solar minimum is 8,32 nT, confirming a direct solar cycle influence in the geomagnetic pulsations intensity for long periods.

  16. The cosmic ray differential diurnal variation dependences on the zenith angle and the geomagnetic disturbance

    NASA Technical Reports Server (NTRS)

    Kavlakov, S.; Georgiev, L.

    1985-01-01

    Simultaneous and continuous muon measurements in two opposite azimuthal directions under equal zenith angles demonstrated the importance of this method for cosmic ray diurnal variation investigations. Lately these measurements were extended by means of improved telescopes. The obtained cosmic ray diurnal variations were presented as intensity differential curves. Theoretical investigations connected the properties of these curves with some interplanetary spece parameters. The harmonics of these curves were interpreted physically. Some order difference curves were introduced. In earlier works some dependences between the parameters characterizing the first and the second harmonics of the differential intensity curves and the geomagnetic activity were found. Then all measurements were carried out under only one zenith angle. The results of investigations of similar dependences using data of simultaneous measurements under three different zenith angles are presented.

  17. Palaeomagnetism of the Upper Miocene- Lower Pliocene lavas from the East Carpathians: contribution to the paleosecular variation of geomagnetic field

    PubMed Central

    Vişan, Mădălina; Panaiotu, Cristian G.; Necula, Cristian; Dumitru, Anca

    2016-01-01

    Investigations of the paleosecular variation of the geomagnetic field on geological timescales depend on globally distributed data sets from lava flows. We report new paleomagnetic results from lava flows of the East Carpathian Mountains (23.6°E, 46.4°N) erupted between 4 and 6 Ma. The average virtual geomagnetic pole position (76 sites) includes the North Geographic Pole and the dispersion of virtual geomagnetic poles is in general agreement with the data of the Time Averaged geomagnetic Field Initiative. Based on this study and previous results from the East Carpathians obtained from 0.04–4 Ma old lava flows, we show that high value of dispersion are characteristic only for 1.5–2.8 Ma old lava flows. High values of dispersion during the Matuyama chron are also reported around 50°N, in the global paleosecular variation data set. More data are needed at a global level to determine if these high dispersions reflect the behaviour of the geomagnetic field or an artefact of inadequate number of sites. This study of the East Carpathians volcanic rocks brings new data from southeastern Europe and which can contribute to the databases for time averaged field and paleosecular variation from lavas in the last 6 Ma. PMID:26997549

  18. Palaeomagnetism of the Upper Miocene- Lower Pliocene lavas from the East Carpathians: contribution to the paleosecular variation of geomagnetic field

    NASA Astrophysics Data System (ADS)

    Vişan, Mădălina; Panaiotu, Cristian G.; Necula, Cristian; Dumitru, Anca

    2016-03-01

    Investigations of the paleosecular variation of the geomagnetic field on geological timescales depend on globally distributed data sets from lava flows. We report new paleomagnetic results from lava flows of the East Carpathian Mountains (23.6°E, 46.4°N) erupted between 4 and 6 Ma. The average virtual geomagnetic pole position (76 sites) includes the North Geographic Pole and the dispersion of virtual geomagnetic poles is in general agreement with the data of the Time Averaged geomagnetic Field Initiative. Based on this study and previous results from the East Carpathians obtained from 0.04–4 Ma old lava flows, we show that high value of dispersion are characteristic only for 1.5–2.8 Ma old lava flows. High values of dispersion during the Matuyama chron are also reported around 50°N, in the global paleosecular variation data set. More data are needed at a global level to determine if these high dispersions reflect the behaviour of the geomagnetic field or an artefact of inadequate number of sites. This study of the East Carpathians volcanic rocks brings new data from southeastern Europe and which can contribute to the databases for time averaged field and paleosecular variation from lavas in the last 6 Ma.

  19. Palaeomagnetism of the Upper Miocene- Lower Pliocene lavas from the East Carpathians: contribution to the paleosecular variation of geomagnetic field.

    PubMed

    Vişan, Mădălina; Panaiotu, Cristian G; Necula, Cristian; Dumitru, Anca

    2016-03-21

    Investigations of the paleosecular variation of the geomagnetic field on geological timescales depend on globally distributed data sets from lava flows. We report new paleomagnetic results from lava flows of the East Carpathian Mountains (23.6°E, 46.4°N) erupted between 4 and 6 Ma. The average virtual geomagnetic pole position (76 sites) includes the North Geographic Pole and the dispersion of virtual geomagnetic poles is in general agreement with the data of the Time Averaged geomagnetic Field Initiative. Based on this study and previous results from the East Carpathians obtained from 0.04-4 Ma old lava flows, we show that high value of dispersion are characteristic only for 1.5-2.8 Ma old lava flows. High values of dispersion during the Matuyama chron are also reported around 50°N, in the global paleosecular variation data set. More data are needed at a global level to determine if these high dispersions reflect the behaviour of the geomagnetic field or an artefact of inadequate number of sites. This study of the East Carpathians volcanic rocks brings new data from southeastern Europe and which can contribute to the databases for time averaged field and paleosecular variation from lavas in the last 6 Ma.

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

    NASA Astrophysics Data System (ADS)

    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

  1. Variations in plasma parameters and magnetic field upon magnetopause crossing at the main phase maximum of the magnetic storm of November 14, 2012

    NASA Astrophysics Data System (ADS)

    Pulinets, M. S.; Kirpichev, I. P.; Antonova, E. E.

    2016-11-01

    Measurements of the plasma parameters and magnetic field upon magnetopause crossings by the THEMIS-A satellite during the large magnetic storm of November 14, 2012, are analyzed. The main specific feature of this event is the magnetopause crossing at the time of the magnetic-storm maximum. An imbalance of total pressure on the magnetopause reaching up to 40% has been observed. An abrupt turn of the magnetic field immediately on the magnetopause is recorded. Inside the magnetosphere, plasma motions have been observed, both along the magnetopause and inward, at velocities of 100-300 km/s. Variations in geomagnetic parameters are analyzed before and after the crossing. It is shown that specific features of the observed crossing may be associated with a sharp change in the magnetospheric current systems during the magnetospheric substorm.

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

    NASA Astrophysics Data System (ADS)

    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

  3. Study of dominating parameters of high speed solar plasma streams in relation to cosmic ray and geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Mishra, B. L.; Agrawal, S. P.

    1985-01-01

    The high speed solar wind streams observed near Earth are generally associated with the solar features, such as solar flares and coronal holes. Past studies of these streams from the two sources have revealed distinctly different effects on cosmic ray intensity, whereas the effect is similar for geomagnetic disturbances. Moreover, the effect of the magnitude of the high speed streams (V) and its rate of increase (dv/dt) has also been a subject of investigation to understand their relative contribution in producing geomagnetic disturbances. From the analysis of some of the fast streams presented here, it is difficult to predict, which one of the two (V, dv/dt) is more effective in producing geo-magnetic disturbances. Further, in most of the cases, no substantial decrease in cosmic ray intensity is observed.

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

    NASA Astrophysics Data System (ADS)

    Yoshida, A.

    2008-12-01

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

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  7. Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter 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. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

  8. Temporal Variation of Different Categories Sunspot Groups since 1996: Their Relation with Geomagnetic Ap and Dst Indices

    NASA Astrophysics Data System (ADS)

    Kilcik, Ali; Ozguc, Atila; Rozelot, Jean Pierre; Donmez, Burcin; Yurchyshyn, Vasyl

    2016-07-01

    We studied the temporal variation of the number of sunspot groups and sunspot counts in these groups in four categories as small (A, B), medium (C), large (D, E, F) and final (H modified Zurich classes) since 1996. Then we compared these data sets with geomagnetic Ap and Dst indices. In results of our analysis we found followings: 1) different categories sunspot groups and sunspot counts in these groups behave differently during a solar cycle. ii) Response of geomagnetic indices to these data sets are also different.

  9. Geomagnetic storm effect on the occurrence of ionospheric irregularities over African equatorial sector using GPS-TEC

    NASA Astrophysics Data System (ADS)

    Amaechi, Paul; Oyeyemi, Elijah; Akala, Andrew

    2016-07-01

    Total electron content (TEC) derived from Global Navigation Satellite Systems (GNSS) measurements provided by the International GNSS Service (IGS) network have been used to study the occurrence of large scale ionospheric irregularities over the African equatorial sector. The rate of change of TEC (ROT) as well as its standard deviation over five minutes (ROTI) were used to monitor the level of irregularities over 3 stations distributed across the three longitudinal sectors of Africa (eastern, central and western longitudinal sectors). The storm effect on irregularities occurrence has been studied in conjunction with the disturbance storm time (Dst) and the z component of the Interplanetary magnetic field (IMFBz) indices during four intense storms which were classified according to their season of occurrence during the year 2015. Irregularities were associated with GPS-TEC fluctuations as seen in the increased ROT and ROTI values especially in the post sunset period. Irregularities were inhibited over all the stations during the storm of March plausibly as a result of electric field conditioned by the southward turning of IMFBz during the pre and post midnight periods. The triggering of irregularities over the western and central stations and their inhibition over the eastern station during the storm of June was controlled by the ring current. The storm effect on irregularities was not evident over the western and central stations but inhibition of irregularities was observed over the eastern station during the storm of September.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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

  13. Ion temperature intensification in southern convection flow channels during the 1 October 2001 geomagnetic storm recovery phase

    NASA Astrophysics Data System (ADS)

    Horvath, Ildiko; Lovell, Brian C.

    2016-09-01

    In this study, we investigate Southern Hemisphere flow channel (FC) events and their underlying thermal and drift variations during the 1 October 2001 storm recovery phase. We adopt FC classification introduced by previous studies for specifying FCs, ranging from FC-0 to FC-4, according to the stages of convection cycle they are related to. Our investigation includes also the subauroral FC known as the subauroral polarization stream (SAPS) and the localized FC underlying plasma density increases crossing the polar cap. For tracking FCs, we utilize multi-instrument data from the Defence Meteorological Satellite Program (DMSP). Since our focus is on the region of magnetic South Pole, we utilize DMSP passes that crossed the magnetic pole. We present various scenarios with polar cross sections, constructed with ion density (Ni), electron and ion temperature (Te; Ti), and zonal and vertical drift (VY; VZ) data, where the location of magnetic pole is marked. Our results show (1) the occurrence of FC-2 in the central polar cap, (2) the propagation of localized FC from the dayside to the nightside across the polar cap implying dayside-nightside coupling across the polar cap, and (3) the structuring of SAPS FC. These scenarios reveal the local intensification of Ti and/or VZ in FCs (a) ranging from FC-0 to FC-3 and (b) specified as SAPS FC and localized FC passing over the magnetic pole. We conclude that strong upward drift, reaching sometimes 1000 m/s, could enhance localized thermospheric impact caused by elevated Ti in FCs.

  14. North-south variations of tropical storm genesis locations in the Western Hemisphere

    NASA Astrophysics Data System (ADS)

    Wang, Chunzai; Wang, Lei; Wang, Xin; Wang, Dongxiao; Wu, Lixin

    2016-11-01

    In the Western Hemisphere, tropical storms or hurricanes form in the North Atlantic and eastern North Pacific. Previous studies have focused on storm variability in the frequency, duration, and intensity in each basin. Here we find that the tropical storm genesis location in one ocean basin ties to the other one. On both interannual and multidecadal time scales, a northward (southward) shift of the tropical storm genesis location is associated with a southward (northward) variation in the other ocean basin. The change of cross-Central America wind in the upper troposphere, which induces an out-of-phase relation of vertical wind shear, bridges storm activity in the two ocean basins. Sea surface temperatures in both the tropical Pacific and North Atlantic can induce the zonal wind change across Central America. An implication of this study is that hurricane outlooks can be improved by considering the two ocean basins together, and thus helping reduce the damage caused by hurricane landfall.

  15. Variation of the ion composition in the ring current during magnetic storms: Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Luo, Hao; Du, Aimin; Ge, Yasong; Cao, Xin; Zhang, Ying; Wang, Yuan

    2015-04-01

    It has been reported that the energy density of the oxygen ions in the ring current region will show more enhancements than protons during magnetic storms. Knowing how the ion composition changes during a magnetic storm is important for understanding the dynamic processes in the inner magnetosphere. By using ion flux data from HOPE and RBSPICE instruments on board the Van Allen probes, we study the energy density variation of both protons and oxygen ions during fifteen strong magnetic storms (minimum Dst < -80 nT) happened during year 2013 to 2014. Results provide important details about the ion composition at different storm stages and different magnetic local times. Results also give important indications about the ion acceleration in the inner magnetosphere and the source of the ring current ions during the magnetic storms.

  16. Variation of strong dust storm events in Northern China during 1978-2007

    NASA Astrophysics Data System (ADS)

    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.

  17. Holocene geomagnetic secular variation recorded by volcanic deposits at Mount St. Helens, Washington

    USGS Publications Warehouse

    Hagstrum, J.T.; Hoblitt, R.P.; Gardner, C.A.; Gray, T.E.

    2002-01-01

    A compilation of paleomagnetic data from volcanic deposits of Mount St. Helens is presented in this report. The database is used to determine signature paleomagnetic directions of products from its Holocene eruptive events, to assign sampled units to their proper eruptive period, and to begin the assembly of a much larger database of paleomagnetic directions from Holocene volcanic rocks in western North America. The paleomagnetic results from Mount St. Helens are mostly of high quality, and generally agree with the division of its volcanic deposits into eruptive episodes based on previous geologic mapping and radiocarbon dates. The Muddy River andesite's paleomagnetic direction, however, indicates that it is more likely part of the Pine Creek eruptive period rather than the Castle Creek period. In addition, the Two-Fingers andesite flow is more likely part of the Middle Kalama eruptive period and not part of the Goat Rocks period. The paleomagnetic data from Mount St. Helens and Mount Hood document variation in the geomagnetic field's pole position over the last ~2,500 years. A distinct feature of the new paleosecular variation (PSV) record, similar to the Fish Lake record (Oregon), indicates a sudden change from rapid clockwise movement of the pole about the Earth's spin axis to relatively slow counterclockwise movement at ???800 to 900 years B.P.

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

    PubMed

    Temerin, Michael; Li, Xinlin

    2015-07-01

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

  19. Overshooting cloud top, variation of tropopause and severe storm formation

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Smith, R. E.

    1984-01-01

    The development of severe multicell thunderstorms leading to the touchdown of six tornados near Pampa, TX, on May 19-20, 1982, is characterized in detail on the basis of weather maps, rawinsonde data, and radar summaries, and the results are compared with GOES rapid-scan IR images. The multicell storm cloud is shown to have formed beginning at 1945 GMT at the point of highest horizontal moisture convergence and lowest tropopause height and to have penetrated the tropopause at 2130 GMT, reaching a maximum altitude and a cloud-top black-body temperature 9 C lower than the tropopause temperature at 2245 GMT and collapsing about 20 min, when the firt tornado touched down. The value of the real-time vertical profiles provided by satellite images in predicting which severe storms will produce tornados or other violent phenomena is stressed.

  20. Spatial and Temporal Variations in the Geomagnetic Field Determined From the Paleomagnetism of Sediment Cores From Scientific Ocean Drilling

    NASA Astrophysics Data System (ADS)

    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.

  1. Monitoring of the mass density profile along the 0° geomagnetic longitude during magnetic storms with the use of ground magnetometers.

    NASA Astrophysics Data System (ADS)

    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.

  2. AN UPDATE OF ITALIAN ARCHEAOINTENSITY DATA AND GEOMAGNETIC FIELD STRENGTH VARIATION DURING THE LAST THREE MILLENNIA

    NASA Astrophysics Data System (ADS)

    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.

  3. The effects of neutral inertia on ionospheric currents in the high-latitude thermosphere following a geomagnetic storm

    SciTech Connect

    Deng, W.; Killeen, T.L.; Burns, A.G. ); Roble, R.G. ); Slavin, J.A.; Wharton, L.E. )

    1993-05-01

    The authors extend previous work with a National Center for Atmospheric Research (NCAR) thermosphere/ionosphere general circulation model (TIGCM), to study dynamo effects in the high latitude thermosphere. Ionospheric convection can drive neutral currents in much the same pattern by means of ion drag reactions. It has been observed that ion currents established during magnetic storms can induce neutral currents which persist for hours after the end of the storm. Model results have shown that such currents can account for up to 80 percent of the Hall currents in the period immediately following storms. Here this previous work is extended and compared with experimental observations. The authors simulate time dependent Hall currents, field-aligned currents, and electrical power fluxes coupling the magnetosphere and ionosphere. They discuss their results in terms of a loaded magnetosphere, which accounts for the fact that the neutral currents can also induce currents and electric fields in the ionosphere.

  4. 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

    NASA Astrophysics Data System (ADS)

    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 o