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Sample records for geomagnetic westward drift

  1. The Study of Westward Drift in the Main Geomagnetic Field

    Directory of Open Access Journals (Sweden)

    G. Bayanjargal

    2013-01-01

    Full Text Available We have obtained a solution for the velocity of westward drift from the induction equation in which an approach for main geomagnetic field was built. Distribution functions B(r, t entered into the induction equation have been built by the observatories' data in North America and the Europe from 1991 to 2006. The longitudinal −0.123 degree/year and latitudinal 0.068 degree/year drifts were defined in North America. And the longitudinal −0.257 degree/year drift was defined in Europe from 1991 to 2006. These drifts are similar to results of other studies.

  2. The Study of Westward Drift in the Main Geomagnetic Field

    OpenAIRE

    Bayanjargal, G.

    2013-01-01

    We have obtained a solution for the velocity of westward drift from the induction equation in which an approach for main geomagnetic field was built. Distribution functions B(r, t) entered into the induction equation have been built by the observatories' data in North America and the Europe from 1991 to 2006. The longitudinal −0.123 degree/year and latitudinal 0.068 degree/year drifts were defined in North America. And the longitudinal −0.257 degree/year drift was defined in Europe from 1991...

  3. Inner Core Rotation from Geomagnetic Westward Drift and a Stationary Spherical Vortex in Earth's Core

    Science.gov (United States)

    Voorhies, C. V.

    1999-01-01

    The idea that geomagnetic westward drift indicates convective leveling of the planetary momentum gradient within Earth's core is pursued in search of a differentially rotating mean state, upon which various oscillations and secular effects might be superimposed. The desired state conforms to roughly spherical boundary conditions, minimizes dissipative interference with convective cooling in the bulk of the core, yet may aide core cooling by depositing heat in the uppermost core and lower mantle. The variational calculus of stationary dissipation applied to a spherical vortex within the core yields an interesting differential rotation profile akin to spherical Couette flow bounded by thin Hartmann layers. Four boundary conditions are required. To concentrate shear induced dissipation near the core-mantle boundary, these are taken to be: (i) no-slip at the core-mantle interface; (ii) geomagnetically estimated bulk westward flow at the base of the core-mantle boundary layer; (iii) no-slip at the inner-outer core interface; and, to describe magnetic locking of the inner core to the deep outer core, (iv) hydrodynamically stress-free at the inner-outer core boundary. By boldly assuming the axial core angular momentum anomaly to be zero, the super-rotation of the inner core is calculated to be at most 1.5 degrees per year.

  4. On the Nocturnal Downward and Westward Equatorial Ionospheric Plasma Drifts During the 17 March 2015 Geomagnetic Storm

    Science.gov (United States)

    Bagiya, Mala S.; Vichare, Geeta; Sinha, A. K.; Sripathi, S.

    2018-02-01

    During quiet period, the nocturnal equatorial ionospheric plasma drifts eastward in the zonal direction and downward in the vertical direction. This quiet time drift pattern could be understood through dynamo processes in the nighttime equatorial ionosphere. The present case study reports the nocturnal simultaneous occurrence of the vertically downward and zonally westward plasma drifts over the Indian latitudes during the geomagnetic storm of 17 March 2015. After 17:00 UT ( 22:10 local time), the vertical plasma drift became downward and coincided with the westward zonal drift, a rarely observed feature of low latitude plasma drifts. The vertical drift turned upward after 18:00 UT, while the zonal drift became eastward. We mainly emphasize here the distinct bipolar type variations of vertical and zonal plasma drifts observed around 18:00 UT. We explain the vertical plasma drift in terms of the competing effects between the storm time prompt penetration and disturbance dynamo electric fields. Whereas, the westward drift is attributed to the storm time local electrodynamical changes mainly through the disturbance dynamo field in addition to the vertical Pedersen current arising from the spatial (longitudinal) gradient of the field aligned Pedersen conductivity.

  5. Electromagnetically driven westward drift and inner-core superrotation in Earth’s core

    OpenAIRE

    Livermore, Philip W.; Hollerbach, Rainer; Jackson, Andrew

    2013-01-01

    Seismic probing of the earth’s deep interior has shown that the inner core, the solid core of our planet, rotates slightly faster (i.e., eastward) than the rest of the earth. Quite independently, observations of the geomagnetic field provide evidence of westward-drifting features at the edge of the liquid outer core. This paper describes a computer model that suggests that the geomagnetic field itself may provide a link between them: The associated electromagnetic torque currently is westward...

  6. Westward ionospheric currents over the dip equator during geomagnetic disturbances

    International Nuclear Information System (INIS)

    Rastogi, R.G.

    1975-01-01

    During geomagnetic disturbed periods, the q type of sporadic E layer near the dip equator is shown to disappear with maximum error of five minutes during the period when the difference of the geomagnetic H field between the equatorial and non-equatorial station decreases below the night level. These periods are identified with the reversal to westward direction of the electrojet currents at the base of the E region around 100 km level irrespective of the changes in the S/subq/ current system which might be produced by the disturbance

  7. Westward equatorial electrojet during daytime hours. [relation to geomagnetic horizontal field depression

    Science.gov (United States)

    Rastogi, R. G.

    1974-01-01

    The phenomenon of the depression of the geomagnetic horizontal field during the daytime hours of magnetically quiet days at equatorial stations is described. These events are generally seen around 0700 and 1600 LT, being more frequent during the evening than the morning hours. The evening events are more frequent during periods of low solar activity and in the longitude region of weak equatorial electrojet currents. The latitudinal extent of the phenomenon is limited to the normal equatorial electrojet region, and on some occasions the phenomenon is not seen at both stations, separated by only a few hours in longitude. During such an event, the latitudinal profile of the geomagnetic vertical field across the equator is reversed, the ionospheric drift near the equator is reversed toward the east, the q type of sporadic E layer is completely absent, and the height of the peak ionization in the F2 region is decreased. It is suggested that these effects are caused by a narrow band of current flowing westward in the E region of the ionosphere and within the latitude region of the normal equatorial electrojet, due to the reversal of the east-west electrostatic field at low latitudes.

  8. Electromagnetically driven westward drift and inner-core superrotation in Earth's core.

    Science.gov (United States)

    Livermore, Philip W; Hollerbach, Rainer; Jackson, Andrew

    2013-10-01

    A 3D numerical model of the earth's core with a viscosity two orders of magnitude lower than the state of the art suggests a link between the observed westward drift of the magnetic field and superrotation of the inner core. In our model, the axial electromagnetic torque has a dominant influence only at the surface and in the deepest reaches of the core, where it respectively drives a broad westward flow rising to an axisymmetric equatorial jet and imparts an eastward-directed torque on the solid inner core. Subtle changes in the structure of the internal magnetic field may alter not just the magnitude but the direction of these torques. This not only suggests that the quasi-oscillatory nature of inner-core superrotation [Tkalčić H, Young M, Bodin T, Ngo S, Sambridge M (2013) The shuffling rotation of the earth's inner core revealed by earthquake doublets. Nat Geosci 6:497-502.] may be driven by decadal changes in the magnetic field, but further that historical periods in which the field exhibited eastward drift were contemporaneous with a westward inner-core rotation. The model further indicates a strong internal shear layer on the tangent cylinder that may be a source of torsional waves inside the core.

  9. Electromagnetically driven westward drift and inner-core superrotation in Earth’s core

    Science.gov (United States)

    Livermore, Philip W.; Hollerbach, Rainer; Jackson, Andrew

    2013-01-01

    A 3D numerical model of the earth’s core with a viscosity two orders of magnitude lower than the state of the art suggests a link between the observed westward drift of the magnetic field and superrotation of the inner core. In our model, the axial electromagnetic torque has a dominant influence only at the surface and in the deepest reaches of the core, where it respectively drives a broad westward flow rising to an axisymmetric equatorial jet and imparts an eastward-directed torque on the solid inner core. Subtle changes in the structure of the internal magnetic field may alter not just the magnitude but the direction of these torques. This not only suggests that the quasi-oscillatory nature of inner-core superrotation [Tkalčić H, Young M, Bodin T, Ngo S, Sambridge M (2013) The shuffling rotation of the earth’s inner core revealed by earthquake doublets. Nat Geosci 6:497–502.] may be driven by decadal changes in the magnetic field, but further that historical periods in which the field exhibited eastward drift were contemporaneous with a westward inner-core rotation. The model further indicates a strong internal shear layer on the tangent cylinder that may be a source of torsional waves inside the core. PMID:24043841

  10. Equatorial westward electrojet impacting equatorial ionization anomaly development during the 6 April 2000 superstorm

    Science.gov (United States)

    Horvath, Ildiko; Lovell, Brian C.

    2013-11-01

    investigate the forward plasma fountain and the equatorial ionosphere in the topside region during the 6 April 2000 superstorm in the Australian sector at ~0900 LT. Space- and ground-based multi-instrument measurements, Coupled Thermosphere-Ionosphere-Plasmasphere Electrodynamics (CTIPe) simulations, and field-aligned observations comprise our results. These reveal an unusual storm development during which the eastward prompt penetration electric (E) field (PPEF) developed and operated under the continuous effects of the westward disturbance dynamo E-field (DDEF) while large-scale traveling ionospheric disturbances (TIDs) traveled equatorward and generated strong equatorward wind surges. We have identified the eastward PPEF by the superfountain effect causing the equatorial ionization anomaly (EIA)'s development with crests situated at ~±28°N (geomagnetic) in the topside ionosphere at ~840 km altitude. The westward DDEF's occurrence is confirmed by mapping the "anti-Sq" current system wherein the equatorial westward current created a weak long-lasting westward electrojet event. Line plots of vertical drift data tracked large-scale TIDs. Four scenarios, covering ~3.5 h in universal time, demonstrate that the westward DDEF became superimposed on the eastward PPEF. As these E-fields of different origins became mapped into the F region, they could interact. Consequently, the eastward PPEF-related equatorial upward E × B drift became locally reduced by up to 75 m/s near the dip equator by the westward DDEF-related equatorial downward E × B drift. Meanwhile, the EIA displayed a better development as equatorial wind surges, reproduced by CTIPe, increased from 501 to 629 m/s, demonstrating the crucial role of mechanical wind effects keeping plasma density high.

  11. The postsunset vertical plasma drift during geomagnetic storms and its effects on the generation of equatorial spread F

    Science.gov (United States)

    Huang, C.

    2017-12-01

    We will present two distinct phenomena related to the postsunset vertical plasma drift and equatorial spread F (ESF) observed by the Communication/Navigation Outage Forecasting System satellite over six years. The first phenomenon is the behavior of the prereversal enhancement (PRE) of the vertical plasma drift during geomagnetic storms. Statistically, storm-time disturbance dynamo electric fields cause the PRE to decrease from 30 to 0 m/s when Dst changes from -60 to -100 nT, but the PRE does not show obvious variations when Dst varies from 0 to -60 nT. The observations show that the storm activities affect the evening equatorial ionosphere only for Dst correlated with the PRE and that the occurrence of small-amplitude ESF irregularities does not show a clear pattern at low solar activity but is anti-correlated with large-amplitude irregularities and the PRE at moderate solar activity. That is, the months and longitudes with high occurrence probability of large-amplitude irregularities are exactly those with low occurrence probability of small-amplitude irregularities, and vice versa. The generation of large-amplitude ESF irregularities is controlled by the PRE, and the generation of small-amplitude ESF irregularities may be caused by gravity waves and other disturbances, rather than by the PRE.

  12. Long-Term Seafloor Electromagnetic Observation in the Northwest Pacific May Detect the Vector Geomagnetic Secular Variation

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    H Toh

    2010-03-01

    Full Text Available Sea Floor ElectroMagnetic Stations (SFEMSs are now operating at two deep seafloor sites called the 'WPB' and the 'NWP' in the West Philippine Basin and the Northwest Pacific Basin, respectively. One of the main objectives of the SFEMSs is to detect the geomagnetic secular variations on the deep seafloor where long-term geomagnetic observations have not so far been achieved. SFEMSs can measure the absolute geomagnetic total force as well as the geomagnetic vector field with precise attitude monitoring systems. The vector geomagnetic time-series that was observed for more than 5 years revealed that the westward drift of the equatorial dipole dominates in the geomagnetic secular variation at the NWP.

  13. Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

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    K.-H. Glassmeier

    Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way, 
    m
    = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed

  14. Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

    Directory of Open Access Journals (Sweden)

    K.-H. Glassmeier

    1999-03-01

    Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way,  m = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed.Key words. Magnetospheric physics (energetic particles , trapped

  15. Comparison of vertical E × B drift velocities and ground-based magnetometer observations of DELTA H in the low latitude under geomagnetically disturbed conditions

    Science.gov (United States)

    Prabhu, M.; Unnikrishnan, K.

    2018-04-01

    In the present work, we analyzed the daytime vertical E × B drift velocities obtained from Jicamarca Unattended Long-term Ionosphere Atmosphere (JULIA) radar and ΔH component of geomagnetic field measured as the difference between the magnitudes of the horizontal (H) components between two magnetometers deployed at two different locations Jicamarca, and Piura in Peru for 22 geomagnetically disturbed events in which either SC has occurred or Dstmax values of daytime vertical E × B drift velocity and peak value of ΔH for the three consecutive days of the events. It was observed that 45% of the events have daytime vertical E × B drift velocity peak in the magnitude range 10-20 m/s and 20-30 m/s and 20% have peak ΔH in the magnitude range 50-60 nT and 80-90 nT. It was observed that the time of occurrence of the peak value of both the vertical E × B drift velocity and the ΔH have a maximum (40%) probability in the same time range 11:00-13:00 LT. We also investigated the correlation between E × B drift velocity and Dst index and the correlation between delta H and Dst index. A strong positive correlation is found between E × B drift and Dst index as well as between delta H and Dst Index. Three different techniques of data analysis - linear, polynomial (order 2), and polynomial (order 3) regression analysis were considered. The regression parameters in all the three cases were calculated using the Least Square Method (LSM), using the daytime vertical E × B drift velocity and ΔH. A formula was developed which indicates the relationship between daytime vertical E × B drift velocity and ΔH, for the disturbed periods. The E × B drift velocity was then evaluated using the formulae thus found for the three regression analysis and validated for the 'disturbed periods' of 3 selected events. The E × B drift velocities estimated by the three regression analysis have a fairly good agreement with JULIA radar observed values under different seasons and solar activity

  16. Simulation of low-latitude ionospheric response to 2015 St. Patrick's Day super geomagnetic storm using ionosonde-derived PRE vertical drifts over Indian region

    Science.gov (United States)

    Joshi, L. M.; Sripathi, S.; Singh, Ram

    2016-03-01

    In this paper, we present low-latitude ionospheric response over Indian longitude to the recent super geomagnetic storm of 17 March 2015, using the Sami2 is Another Model of the Ionosphere (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 (1) Dst reaches as low as -228 nT and (2) prompt penetration of eastward electric field coincided with evening hours PRE. The daytime vertical E × B 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 E × B drift along with equatorward disturbance wind, indicate suppression of the daytime EIA. SAMI2 simulations considering the disturbance wind during the recovery phase suggest 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 indicates that model does reproduce enhancement of the EIA during the main phase and suppression of the EIA during the recovery phase of the superstorm. However, peculiarities pertaining to the ionospheric response to prompt penetration electric field in the Indian sector vis-a-vis earlier reports from American sector have been discussed.

  17. On the lifetime and extent of an auroral westward flow channel (AWFC observed during a magnetospheric substorm

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    M. L. Parkinson

    Full Text Available A -190-nT negative bay in the geomagnetic X component measured at Macquarie Island ( -65° L showed that an ionospheric substorm occurred during 09:58 to 11:10 UT on 27 February 2000. Signatures of an auroral westward flow channel (AWFC were observed nearly simultaneously in the backscatter power, LOS Doppler velocity, and Doppler spectral width measured using the Tasman International Geospace Environment Radar (TIGER, a Southern Hemisphere HF SuperDARN radar. Many of the characteristics of the AWFC were similar to those occurring during a polarisation jet (PJ, or subauroral ion drift (SAID event, and suggest that it may have been a pre-cursor to a fully developed, intense westward flow channel satisfying all of the criteria defining a PJ/SAID. A beam-swinging analysis showed that the westward drifts (poleward electric field associated with the flow channel were very structured in time and space, but the smoothed velocities grew to ~ 800 ms-1 (47 mVm-1 during the 22-min substorm onset interval 09:56 to 10:18 UT. Maximum west-ward drifts of >1.3 km s-1 (>77 mVm-1 occurred during a ~ 5-min velocity spike, peaking at 10:40 UT during the expansion phase. The drifts decayed rapidly to ~ 300 ms-1 (18 mVm-1 during the 6-min recovery phase interval, 11:04 to 11:10 UT. Overall, the AWFC had a lifetime of 74 min, and was located near -65° L in the evening sector west of the Harang discontinuity. The large westward drifts were confined to a geographic zonal channel of longitudinal ex-tent >20° (>1.3 h magnetic local time, and latitudinal width ~2° L. Using a half-width of ~ 100 km in latitude, the peak electric potential was >7.7 kV. However, a transient velocity of >3.1 km s-1 with potential >18.4 kV was observed further poleward at the end of the recovery phase. Auroral oval boundaries determined

  18. Geomagnetic storm effects in ionospheric TEC at an euatorial station: contribution of EXB drifts and meridional neutral winds

    International Nuclear Information System (INIS)

    Dabas, R.S.; Jain, A.R.

    1985-01-01

    Storm-time variations in TEC measurements at the Indian station Ootacamund with IEC data for four stations in the anomaly region. Variations in Nsub(T)(OOTY) are found to be smaller compared to those observed at anomaly stations. The equatorial electrojet control of Nsub(T)(OOTY) is weaker compared to that of Nsub(m)F2. This result and absence of midday biteout in Nsub(T)(OOTY) are interpreted in terms of plasma exchange between ionosphere and plasmasphere which, to some extent, compensates the loss of plasma in the column due to E x B drifts. The anomaly depth is found to be well correlated with the electrojet strength. It is also noticed that for the same anomaly is weaker on a storm day than for quiet days. This is interpreted in terms of converging equatorward meridional winds. Thus, ionosphere-plasmasphere plasma exchange and, during disturbed period, the converging equatorward meridional winds also have significant effects on the distribution of ionization at these latitudes though the E x B drifts are most important in affecting the ionization distribution at low latitudes. (author)

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

    DEFF Research Database (Denmark)

    Aubert, Julien; Finlay, Chris; Fournier, Alexandre

    2013-01-01

    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 coupling5 aligns the inner core with the mantle, forcing the flow of liquid metal in the outer core into a giant, westward drifting, sheet...... release in the outer core which in turn distorts the gyre, forcing it to become eccentric, in agreement with recent core flow inversions6, 10, 11. This bottom-up heterogeneous driving of core convection dominates top-down driving from mantle thermal heterogeneities, and localizes magnetic variations......Temporal changes in the Earth’s magnetic field, known as geomagnetic secular variation, occur most prominently at low latitudes in the Atlantic hemisphere1, 2 (that is, from −90 degrees east to 90 degrees east), whereas in the Pacific hemisphere there is comparatively little activity...

  20. The westward drift of the lithosphere: A tidal ratchet?

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    A. Carcaterra

    2018-03-01

    Full Text Available Is the westerly rotation of the lithosphere an ephemeral accidental recent phenomenon or is it a stable process of Earth's geodynamics? The reason why the tidal drag has been questioned as the mechanism determining the lithospheric shift relative to the underlying mantle is the apparent too high viscosity of the asthenosphere. However, plate boundaries asymmetries are a robust indication of the ‘westerly’ decoupling of the entire Earth's outer lithospheric shell and new studies support lower viscosities in the low-velocity layer (LVZ atop the asthenosphere. Since the solid Earth tide oscillation is longer in one side relative to the other due to the contemporaneous Moon's revolution, we demonstrate that a non-linear rheological behavior is expected in the lithosphere mantle interplay. This may provide a sort of ratchet favoring lowering of the LVZ viscosity under shear, allowing decoupling in the LVZ and triggering the westerly motion of the lithosphere relative to the mantle.

  1. How does the predicted geomagnetic main field variation alter the thermosphere-ionosphere storm-time response?

    Science.gov (United States)

    Maute, A. I.; Lu, G.; Richmond, A. D.

    2017-12-01

    Earth's magnetic main field plays an important role in the thermosphere-ionosphere (TI) system, as well as its coupling to Earth's magnetosphere. The ionosphere consists of a weakly ionized plasma strongly influenced by the main field and embedded in the thermosphere. Therefore, ion-neutral coupling and ionospheric electrodynamics can influence the plasma distribution and neutral dynamics. There are strong longitude variations of the TI storm response. At high latitude magnetosphere-ionosphere coupling is organized by the geomagnetic main field, leading in general to stronger northern middle latitude storm time response in the American sector due to the geomagnetic dipole location. In addition, the weak geomagnetic main field in the American sector leads to larger local ExB drift and can alter the plasma densities. During geomagnetic storms the intense energy input into the high latitude region is redistributed globally, leading to thermospheric heating, wind circulation changes and alterations of the ionospheric electrodynamics. The storm time changes are measurable in the plasma density, ion drift, temperature, neutral composition, and other parameters. All these changes depend, to some degree, on the geomagnetic main field which changes on decadal time scales. In this study, we employ a forecast model of the geomagnetic main field based on data assimilation and geodynamo modeling [Aubert et al., 2015]. The main field model predicts that in 50 years the South Atlantic Anomaly is further weakened by 2 mT and drifts westward by approximately 10o. The dipole axis moves northward and westward by 2o and 6o, respectively. Simulating the March 2015 geomagnetic storm with the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM) driven by the Assimilative Mapping of Ionospheric Electrodynamics (AMIE), we evaluate the thermosphere-ionosphere response using the geomagnetic main field of 2015, 2065, and 2115. We compare the TI response for 2015 with

  2. Plasma sheet instability related to the westward traveling surge

    International Nuclear Information System (INIS)

    Roux, A.; Perraut, S.; Robert, P.; Morane, A.; Pedersen, A.; Korth, A.; Kremser, G.; Aparicio, B.; Rodgers, D.; Pellinen, R.

    1991-01-01

    The detailed analysis of an isolated dispersionless substorm is performed on the basis of field and particle data collected in situ by the geostationary satellite GEOS 2 and of data from ground-based instruments installed close to the GEOS 2 magnetic footprint. These data give evidence for (1) quasi-periodic variations of the magnetic field configuration, which is alternatively taillike and dipolelike, (2) in-phase oscillations of the flux of energetic electrons, which is high when the configuration is dipolelike and vice versa, (3) a gradient in the flux of energetic ions, which is, on the average, earthward but undergoes large fluctuations around this average direction, and (4) large transient fluctuations of the quasi-dc electric field, which reverses its direction from eastward to westward. It is shown that these results are consistent with the development of an instability which leads to a westward propagating wave. The source of the instability is the differential drift of energetic electrons and ions in a highly stressed magnetic field configuration (in a high β plasma). Evidence is given for a system of localized field-aligned currents flowing alternately earthward and equatorward at the leading and trailing edges of the westward propagating wave. This current system resulting from the temporal development of the instability produces the so-called Pi 2 pulsations, at the ionospheric level. The closure of this current system in the equatorial region leads to a current antiparallel to the tail current, and therefore to its reduction or cancellation. This reduction/cancellation of the tail current restores the dipole magnetic field (dipolarization) and generates a large westward directed induced electric field (injection)

  3. SuperDARN Hokkaido radar observation of westward flow enhancement in subauroral latitudes

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    R. Kataoka

    2009-04-01

    Full Text Available Westward flow enhancement in subauroral latitudes is investigated based on the first one and a half year observation of the SuperDARN Hokkaido radar. A total of 15 events are identified with the criteria of westward flow speed of >1.0 km/s in magnetic latitude from 45 to 65 deg during geomagnetically disturbed period of Kp>3+ at 20 magnetic local time. It is found that especially during the storm recovery phase, the flow enhancement occurs in broad range of Dst amplitude, and the occurrence latitude depends on the amplitude of Dst. It is also found that the disturbed Kp condition is not sufficient for the appearance of the subauroral flow enhancement as seen by Hokkaido radar while storm-like Dst condition is necessary, supporting the idea that ring current particles play an essential role to enhance the westward flow in subauroral latitudes via magnetosphere-ionosphere coupling through the field-aligned current.

  4. Drift velocities of 150-km Field-Aligned Irregularities observed by the Equatorial Atmosphere Radar

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    Yuichi Otsuka

    2013-11-01

    Full Text Available Between 130 and 170 km altitude in the daytime ionosphere, the so-called 150-km field-aligned irregularities (FAIs have been observed since the 1960s at equatorial regions with several very high frequency (VHF radars. We report statistical results of 150-km FAI drift velocities on a plane perpendicular to the geomagnetic field, acquired by analyzing the Doppler velocities of 150-km FAIs observed with the Equatorial Atmosphere Radar (EAR at Kototabang, Indonesia during the period from Aug. 2007 to Oct. 2009. We found that the southward/upward perpendicular drift velocity of the 150-km FAIs tends to decrease in the afternoon and that this feature is consistent with that of F-region plasma drift velocities over the magnetic equator. The zonal component of the 150-km FAI drift velocity is westward and decreases with time, whereas the F-region plasma drift velocity observed with the incoherent scatter radar at Jicamarca, Peru, which is westward, reaches a maximum at about noon. The southward/upward and zonal drift velocities of the 150-km FAIs are smaller than that of the F-region plasma drift velocity by approximately 3 m/s and 25 m/s, respectively, on average. The large difference between the 150-km FAI and F-region plasma drift velocities may not arise from a difference in the magnetic latitudes at which their electric fields are generated. Electric fields generated at the altitude at which the 150-km FAIs occur may not be negligible.

  5. Geomagnetism 4

    CERN Document Server

    Jacobs, John A

    2013-01-01

    Geomagnetism, Volume 4 focuses on the processes, methodologies, technologies, and approaches involved in geomagnetism, including electric fields, solar wind plasma, pulsations, and gravity waves.The selection first offers information on solar wind, magnetosphere, and the magnetopause of the Earth. Discussions focus on magnetopause structure and transfer processes, magnetosphere electric fields, geomagnetically trapped radiation, microstructure of the solar wind plasma, and hydro magnetic fluctuations and discontinuities. The text then examines geomagnetic tail, neutral upper atmosphere, and ge

  6. Geomagnetism and paleomagnetism 1979-1983

    Science.gov (United States)

    Fuller, M.

    My function, in writing these notes, is to bring you up to date in Geomagnetism and Paleomagnetism, in as painless a manner as possible—without tears, as the French language texts for tourists used to promise. In writing this account of progress in the past quadrennium, I must first acknowledge that it is a personal and subjective viewpoint;; another reporter would surely emphasize other developments. Yet, there is some virture in writing of things, about which one knows something, so I leave to future reporters the task of redresssing the balance in matters covered.At the outset, one very sad event must be recorded. On April 3, 1981, Sir Edward Bullard died. His published work alone marks him as one of the leaders of geomagnetism in our times. Yet his contribution was much greater; many an American geophysicist, as well as a whole generation of British colleagues, have felt the benefit of his perceptive advice on their research. To those who saw him in the last few months of his life, his courage in the face of his illness was a remarkable example of fortitude. It is by now well known that the definitive paper, which he wrote with Malin, on secular variation at London, was only completed immediately before his death. The transmittal letter had been typed, but death prevented him from signing it. Bullard returned in this final paper to a topic to which he had contributed much. In it, he notes the role of Halley, who first described the phenomenon of westward drift, to which Bullard gave a new numerical precision, two and a half centuries later. I seem to remember Bullard saying in a lecture years ago that, while the Newtons of this world seem other than mortal, Halley was a scientist whose life and acheivements could encourage one's own efforts. Bullard, like Halley, inspires and encourages us.

  7. Calaveras reversed: westward younging is indicated.

    Science.gov (United States)

    Bateman, P.C.; Harris, A.G.; Kistler, R.W.; Krauskopf, K.B.

    1985-01-01

    Samples of limestone collected from strata in the southern part of the western metamorphic belt of the Sierra Nevada, which traditionally have been assigned to the Calaveras Formation, have yielded Early Triassic conodonts, and samples of metavolcanic rock indicate an Early Jurassic Rb-Sr age. These ages, together with general westward younging of units rather than with eastward younging as has been assumed until recently by many workers, chiefly on the basis of sparse oservations of bedding facings. The rocks are strongly deformed, and the possibility that tectonism rather than stratigraphic succession accounts for the age pattern cannot be dismissed.-Authors

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

    Directory of Open Access Journals (Sweden)

    F. D'Ajello Caracciolo

    2011-06-01

    Full Text Available Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleosecular variation ((PSV are available. To this end, we re-evaluate the whole Italian geomagnetic directional dataset, consisting of 833 and 696 declination and inclination measurements, respectively, carried out since 1640 AD at several localities. All directions were relocated via the virtual geomagnetic pole method to Stromboli (38.8° N, 15.2° E, the rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method by French data (for period 1670–1789, and by nearby Italian sites/years (for periods 1640–1657 and 1790–1962. Using post-1825 declination values, we obtain a 0.46 ± 0.19° yr−1 westward drift of the geomagnetic field for Italy. The original observation years were modified, considering such drift value, to derive at a drift-corrected relocated dataset. Both datasets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000 and Pavon-Carrasco et al. (2009. However, the drift-corrected dataset minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933–1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated datasets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. The curve comparison suggests that both available field models yield the best available SV curve to perform paleomagnetic dating of 1600–1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the 19th century. For the 20th century, the global model by

  9. Correlations between the geomagnetic field variations, the fluctuations of the earth`s rotation and climate change

    Energy Technology Data Exchange (ETDEWEB)

    Greiner-Mai, H; Jochmann, H

    1995-03-01

    The amplitude spectra of global geophysical phenomena were investigated to motivate research of physical connections between them. The suggested causality was derived from comparison of the spectra, and from cross correlation functions. The following global parameters were discussed: For the earth rotation by the variations of the length of day, for the geomagnetic variation by the global field intensity, changes of the dipole axis and the westward drift, and for climate change by the atmospheric excitation function derived from air pressure variations, and temperature variations. The model of atmospheric excitation, which can be proved most exactly for the annual variations of length of day, is responsible for the 11 and 22 years periods, too. It failed for longer periods, e.g. partially for the 30 years periods and completely for the 60 to 80 years periods, which were also discovered in the mean temperature and geomagnetic field variations. Therefore, it was suggested that longer periods in climate change and in the variations of the earth`s rotation are caused independently by the same process in the earth core, provided that a physical influence of the geomagnetic field on climate will be accepted in future. The investigation was completed by comparison with the spectra of some local temperature variations in Europe. (orig.)

  10. Geomagnetic storms

    International Nuclear Information System (INIS)

    McNamara, A.G.

    1980-01-01

    Disturbances due to geomagnetic storms can affect the functioning of communications satellites and of power lines and other long conductors. Two general classes of geomagnetic activity can be distinguished: ionospheric current flow (the auroral electrojet), and magnetospheric compression. Super magnetic storms, such as the one of August 1972, can occur at any time and average about 17 occurrences per century. Electrical transmission systems can be made more tolerant of such events at a price, but the most effective way to minimize damage is by better operator training coupled with effective early warning systems. (LL)

  11. Archeomagnetic Intensity Spikes: Global or Regional Geomagnetic Field Features?

    Directory of Open Access Journals (Sweden)

    Monika Korte

    2018-03-01

    Full Text Available Variations of the geomagnetic field prior to direct observations are inferred from archeo- and paleomagnetic experiments. Seemingly unusual variations not seen in the present-day and historical field are of particular interest to constrain the full range of core dynamics. Recently, archeomagnetic intensity spikes, characterized by very high field values that appear to be associated with rapid secular variation rates, have been reported from several parts of the world. They were first noted in data from the Levant at around 900 BCE. A recent re-assessment of previous and new Levantine data, involving a rigorous quality assessment, interprets the observations as an extreme local geomagnetic high with at least two intensity spikes between the 11th and 8th centuries BCE. Subsequent reports of similar features from Asia, the Canary Islands and Texas raise the question of whether such features might be common occurrences, or whether they might even be part of a global magnetic field feature. Here we use spherical harmonic modeling to test two hypotheses: firstly, whether the Levantine and other potential spikes might be associated with higher dipole field intensity than shown by existing global field models around 1,000 BCE, and secondly, whether the observations from different parts of the world are compatible with a westward drifting intense flux patch. Our results suggest that the spikes originate from intense flux patches growing and decaying mostly in situ, combined with stronger and more variable dipole moment than shown by previous global field models. Axial dipole variations no more than 60% higher than observed in the present field, probably within the range of normal geodynamo behavior, seem sufficient to explain the observations.

  12. The Storm Time Evolution of the Ionospheric Disturbance Plasma Drifts

    Science.gov (United States)

    Zhang, Ruilong; Liu, Libo; Le, Huijun; Chen, Yiding; Kuai, Jiawei

    2017-11-01

    In this paper, we use the C/NOFS and ROCSAT-1 satellites observations to analyze the storm time evolution of the disturbance plasma drifts in a 24 h local time scale during three magnetic storms driven by long-lasting southward IMF Bz. The disturbance plasma drifts during the three storms present some common features in the periods dominated by the disturbance dynamo. The newly formed disturbance plasma drifts are upward and westward at night, and downward and eastward during daytime. Further, the disturbance plasma drifts are gradually evolved to present significant local time shifts. The westward disturbance plasma drifts gradually migrate from nightside to dayside. Meanwhile, the dayside downward disturbance plasma drifts become enhanced and shift to later local time. The local time shifts in disturbance plasma drifts are suggested to be mainly attributed to the evolution of the disturbance winds. The strong disturbance winds arisen around midnight can constantly corotate to later local time. At dayside the westward and equatorward disturbance winds can drive the F region dynamo to produce the poleward and westward polarization electric fields (or the westward and downward disturbance drifts). The present results indicate that the disturbance winds corotated to later local time can affect the local time features of the disturbance dynamo electric field.

  13. Are North Atlantic Multidecadal SST Anomalies Westward Propagating?

    NARCIS (Netherlands)

    Feng, Qingyi; Dijkstra, Hendrik

    2014-01-01

    The westward propagation of sea surface temperature (SST) anomalies is one of the main characteristics of one of the theories of the Atlantic Multidecadal Oscillation. Here we use techniques from complex network modeling to investigate the existence of the westward propagation in the North Atlantic

  14. STARE velocities: 2. Evening westward electron flow

    Directory of Open Access Journals (Sweden)

    M. Uspensky

    2004-04-01

    Full Text Available Four evening events and one morning event of joint EISCAT/STARE observations during ~22h are considered and the differences between observed STARE line-of-sight (l-o-s velocities and EISCAT electron drift velocities projected onto the STARE beams are studied. We demonstrate that the double-pulse technique, which is currently in use in the STARE routine data handling, typically underestimates the true phase velocity as inferred from the multi-pulse STARE data. We show that the STARE velocities are persistently smaller (1.5–2 times than the EISCAT velocities, even for the multi-pulse data. The effect seems to be more pronounced in the evening sector when the Finland radar observes at large flow angles. We evaluate the performance of the ion-acoustic approach (IAA, Nielsen and Schlegel, 1985 and the off-orthogonal fluid approach (OOFA, Uspensky et al., 2003 techniques to predict the true electron drift velocity for the base event of 12 February 1999. The IAA technique predicts the convection reasonably well for enhanced flows of >~1000m/s, but not so well for slower ones. By considering the EISCAT N(h profiles, we derive the effective aspect angle and effective altitude of backscatter, and use this information for application of the OOFA technique. We demonstrate that the OOFA predictions for the base event are superior over the IAA predictions and thus, we confirm that OOFA predicts the electron velocities reasonably well in the evening sector, in addition to the morning sector, as concluded by Uspensky et al. (2003. To check how "robust" the OOFA model is and how successful it is for convection estimates without the EISCAT support, we analysed three additional evening events and one additional morning event for which information on N(h profiles was intentionally ignored. By accepting the mean STARE/EISCAT velocity ratio of 0.55 and the mean azimuth rotation of 9° (derived for the basic event, we show that the OOFA performs

  15. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade....... The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites....

  16. Geographical localisation of the geomagnetic secular variation

    DEFF Research Database (Denmark)

    Aubert, Julien; Finlay, Chris; Olsen, Nils

    2013-01-01

    the model and geomagnetic data previously processed in the same way. Our results suggest that conservation of angular momentum and heterogeneous thermochemical boundary control in the coupled inner core / outer core / mantle system are central to understanding how Earth’s magnetic field currently evolves......., westward moving, magnetic flux patches at the core surface. Despite its successes in explaining the main morphological properties of Earth’s magnetic field, self-consistent numerical modelling of the geodynamo has so far failed to reproduce this field variation pattern. Furthermore its magnetohydrodynamic...... control from either, or both, the inner-core boundary and the core-mantle boundary. In addition to presenting an Earth-like magnetic field morphology, these new numerical models also reproduce the morphology and localization of geomagnetic secular variation. In our models, the conservation of the angular...

  17. Zonal wind observations during a geomagnetic storm

    Science.gov (United States)

    Miller, N. J.; Spencer, N. W.

    1986-01-01

    In situ measurements taken by the Wind and Temperature Spectrometer (WATS) onboard the Dynamics Explorer 2 spacecraft during a geomagnetic storm display zonal wind velocities that are reduced in the corotational direction as the storm intensifies. The data were taken within the altitudes 275 to 475 km in the dusk local time sector equatorward of the auroral region. Characteristic variations in the value of the Dst index of horizontal geomagnetic field strength are used to monitor the storm evolution. The detected global rise in atmospheric gas temperature indicates the development of thermospheric heating. Concurrent with that heating, reductions in corotational wind velocities were measured equatorward of the auroral region. Just after the sudden commencement, while thermospheric heating is intense in both hemispheres, eastward wind velocities in the northern hemisphere show reductions ranging from 500 m/s over high latitudes to 30 m/s over the geomagnetic equator. After 10 hours storm time, while northern thermospheric heating is diminishing, wind velocity reductions, distinct from those initially observed, begin to develop over southern latitudes. In the latter case, velocity reductions range from 300 m/s over the highest southern latitudes to 150 m/s over the geomagnetic equator and extend into the Northern Hemisphere. The observations highlight the interhemispheric asymmetry in the development of storm effects detected as enhanced gas temperatures and reduced eastward wind velocities. Zonal wind reductions over high latitudes can be attributed to the storm induced equatorward spread of westward polar cap plasma convection and the resulting plasma-neutral collisions. However, those collisions are less significant over low latitudes; so zonal wind reductions over low latitudes must be attributed to an equatorward extension of a thermospheric circulation pattern disrupted by high latitude collisions between neutrals transported via eastward winds and ions

  18. Geomagnetic storms and electric fields in the equatorial ionosphere

    International Nuclear Information System (INIS)

    Rastogi, R.G.

    1977-01-01

    Using direct measurements of equatorial electric field during a geomagnetic storm it is shown that the large decrease in the field observed near the dip equator is due to the reversal of the equatorial electrojet current. This is caused by the imposition of an additional westward electric field on the equatorial ionosphere which was originated by the interaction of solar wind with the interplanetary magnetic field. (author)

  19. Geomagnetic Principal Magnetic Storms

    Data.gov (United States)

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

  20. Tectonically asymmetric Earth: From net rotation to polarized westward drift of the lithosphere

    Directory of Open Access Journals (Sweden)

    Carlo Doglioni

    2015-05-01

    Full Text Available The possibility of a net rotation of the lithosphere with respect to the mantle is generally overlooked since it depends on the adopted mantle reference frames, which are arbitrary. We review the geological and geophysical signatures of plate boundaries, and show that they are markedly asymmetric worldwide. Then we compare available reference frames of plate motions relative to the mantle and discuss which is at best able to fit global tectonic data. Different assumptions about the depths of hotspot sources (below or within the asthenosphere, which decouples the lithosphere from the deep mantle predict different rates of net rotation of the lithosphere relative to the mantle. The widely used no-net-rotation (NNR reference frame, and low (1°/Ma net rotation (shallow hotspots source, all plates, albeit at different velocity, move westerly along a curved trajectory, with a tectonic equator tilted about 30° relative to the geographic equator. This is consistent with the observed global tectonic asymmetries.

  1. Geomagnetic secular variation from recent lake sediments, ancient fireplaces and historical measurements in southeastern Australia

    Science.gov (United States)

    Barton, C. E.; Barbetti, Mike

    1982-07-01

    Compilations of historical observations, archaeomagnetic data from ancient fireplaces and palaemagetic results from short cores of sediment from lakes in southeastern Australia, particularly Lake Keilambete, provide a detailed record of the geomagnetic secular variation during the last 3000 years. The independent sets of data are in good agreement if the radiocarbon time scale for the lacustrine record is about 450 years too old. The error is attributed to systematic incorporation of ancient carbon into the lake floor sediments, mainly through erosion of sediment on the crater walls at times of low water level. A significant lag between deposition and the acquisition of stable magnetic remanence is ruled out. Inclination has been abnormally steep during the last 500 years but remained fairly close to the axial dipole field value prior to that. During the last 1000 years the predominant sense of looping of the magnetic vector corresponds to westward drift of the nondipole field. Secular variations on a time scale of ˜ 100 years can be resolved by the lacustrine record.

  2. Geomagnetic field of earth

    International Nuclear Information System (INIS)

    Delipetrev, Marjan; Delipetrev, Blagoj; Panovska, Sanja

    2008-01-01

    In this paper is introduced the theory of geomagnetic field of the Earth. A homogenous and isotropic sphere is taken for a model of Earth with a bar magnet at its center as a magnetic potential. The understanding of the real origin of geomagnetic field produced from differential rotation of inner core with respect to the outer core of Earth is here presented. Special attention is given to the latest observed data of the established net of geomagnetic repeat stations in the Republic of Macedonia. Finally, the maps of elements of geomagnetic field and the equation for calculation of normal magnetic field of Earth are provided. (Author)

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

    International Nuclear Information System (INIS)

    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 mid-latitude 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. We infer 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 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

  4. Stokes drift

    Science.gov (United States)

    van den Bremer, T. S.; Breivik, Ø.

    2017-12-01

    During its periodic motion, a particle floating at the free surface of a water wave experiences a net drift velocity in the direction of wave propagation, known as the Stokes drift (Stokes 1847 Trans. Camb. Philos. Soc. 8, 441-455). More generally, the Stokes drift velocity is the difference between the average Lagrangian flow velocity of a fluid parcel and the average Eulerian flow velocity of the fluid. This paper reviews progress in fundamental and applied research on the induced mean flow associated with surface gravity waves since the first description of the Stokes drift, now 170 years ago. After briefly reviewing the fundamental physical processes, most of which have been established for decades, the review addresses progress in laboratory and field observations of the Stokes drift. Despite more than a century of experimental studies, laboratory studies of the mean circulation set up by waves in a laboratory flume remain somewhat contentious. In the field, rapid advances are expected due to increasingly small and cheap sensors and transmitters, making widespread use of small surface-following drifters possible. We also discuss remote sensing of the Stokes drift from high-frequency radar. Finally, the paper discusses the three main areas of application of the Stokes drift: in the coastal zone, in Eulerian models of the upper ocean layer and in the modelling of tracer transport, such as oil and plastic pollution. Future climate models will probably involve full coupling of ocean and atmosphere systems, in which the wave model provides consistent forcing on the ocean surface boundary layer. Together with the advent of new space-borne instruments that can measure surface Stokes drift, such models hold the promise of quantifying the impact of wave effects on the global atmosphere-ocean system and hopefully contribute to improved climate projections. This article is part of the theme issue 'Nonlinear water waves'.

  5. Re-Evaluation of Geomagnetic Field Observation Data at Syowa Station, Antarctica

    Directory of Open Access Journals (Sweden)

    K Takahashi

    2013-05-01

    Full Text Available The Japanese Antarctic Research Expedition has conducted geomagnetic observations at Syowa Station, Antarctica, since 1966. Geomagnetic variation data measured with a fluxgate magnetometer are not absolute but are relative to a baseline and show drift. To enhance the importance of the geomagnetic data at Syowa Station, therefore, it is necessary to correct the continuous variation data by using absolute baseline values acquired by a magnetic theodolite and proton magnetometer. However, the database of baseline values contains outliers. We detected outliers in the database and then converted the geomagnetic variation data to absolute values by using the reliable baseline values.

  6. Characteristic features of the geomagnetic field of the Earth

    International Nuclear Information System (INIS)

    Petrova, G.N.

    1978-01-01

    The laws of the earth magnetism permitting to make a model of the earth magnetic field are popularly investigated. The modern methods of investigations used in the development of geomagnetism and determining the quantity and direction of the earth magnetic field from the moment of rock formation are described. Considered are the characteristic peculiarities of geomagnetic field: the inclination of the magnetic axis to the rotational axis of the Earth, the western drift of the geomagnetic field, the magnetic field asymmetry, its pole exchange and secular variations. The sources of the continuous magnetic field are investigated. The theory of hydromagnatic dinamo operating in the earth core is described. According to the invariance of the geomagnetic field characteristics it is possible to assume that the core has not significantly evolved for milliard years

  7. Reducing Pesticide Drift

    Science.gov (United States)

    Provides information about pesticide spray drift, including problems associated with drift, managing risks from drift and the voluntary Drift Reduction Technology program that seeks to reduce spray drift through improved spray equipment design.

  8. Drift chamber

    International Nuclear Information System (INIS)

    Inagaki, Yosuke

    1977-01-01

    Drift chamber is becoming an important detector in high energy physics as a precision and fast position detector because of its high spatial resolution and count-rate. The basic principle is that it utilizes the drift at constant speed of electrons ionized along the tracks of charged particles towards the anode wire in the nearly uniform electric field. The method of measuring drift time includes the analog and digital ones. This report describes about the construction of and the application of electric field to the drift chamber, mathematical analysis on the electric field and equipotential curve, derivation of spatial resolution and the factor for its determination, and selection of gas to be used. The performance test of the chamber was carried out using a small test chamber, the collimated β source of Sr-90, and 500 MeV/C electron beam from the 1.3 GeV electron synchrotron in the Institute of Nuclear Study, University of Tokyo. Most chambers to date adopted one dimensional read-out, but it is very advantageous if the two dimensional read-out is feasible with one chamber when the resolution in that direction is low. The typical methods of delay line and charge division for two dimensional read-out are described. The development of digital read-out system is underway, which can process the signal of a large scale drift chamber at high speed. (Wakatsuki, Y.)

  9. Geomagnetic field, global pattern

    OpenAIRE

    Macmillan, Susan

    2011-01-01

    The geomagnetic field is generated in the fluid outer core region of the Earth by electrical currents flowing in the slowly moving molten iron. In addition to sources in the Earth’s core, the geomagnetic field observable on the Earth’s surface has sources in the crust and in the ionosphere and magnetosphere. The signal from the core dominates, accounting for over 95% of the field at the Earth’s surface. The geomagnetic field varies on a range of scales, both temporal and spatial; the...

  10. Geomagnetic Storm Sudden Commencements

    Data.gov (United States)

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

  11. Geomagnetic Indices Bulletin (GIB)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Geomagnetic Indices Bulletin is a one page sheet containing the magnetic indices Kp, Ap, Cp, An, As, Am and the provisional aa indices. The bulletin is published...

  12. Geomagnetic aa Indices

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The geomagnetic aa indices are the continuation of the series beginning in the year 1868. A full description of these indices is given in the International...

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

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

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

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

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    1999-03-01

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

  15. A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

    Energy Technology Data Exchange (ETDEWEB)

    Williams, A.P.; Funk, Chris [University of California, Santa Barbara, Geography Department, Santa Barbara, CA (United States)

    2011-12-15

    Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by {proportional_to}40 longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55 E-140 W) since at least 1948, explaining more variance than anomalies associated with the El Nino-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980-2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the 'long-rains' season of March-June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more 'El Nino-like' conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning. (orig.)

  16. International Geomagnetic Reference Field

    DEFF Research Database (Denmark)

    Finlay, Chris; Maus, S.; Beggan, C. D.

    2010-01-01

    The eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V‐MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field...... model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity...

  17. Occurrence and zonal drifts of small-scale ionospheric irregularities over an equatorial station during solar maximum - Magnetic quiet and disturbed conditions

    Science.gov (United States)

    Muella, M. T. A. H.; de Paula, E. R.; Kantor, I. J.; Rezende, L. F. C.; Smorigo, P. F.

    2009-06-01

    occasionally may present westward drift. The present work is important to evaluate the behavior of the ionospheric irregularities at equatorial latitudes under geomagnetically quiet and disturbed conditions, which is one of the most relevant themes in the space weather studies.

  18. Geomagnetic radioflash unfold (GRUF)

    International Nuclear Information System (INIS)

    Malik, J.S.

    1975-08-01

    A method of inverting the geomagnetic component of the radioflash signal from a nuclear explosion to obtain the gamma-ray time history was proposed by E. D. Dracott of the Atomic Weapons Research Establishment. A simplified development of an elaboration by B. R. Suydam has been programmed for small calculators in a form suitable for interim field analysis of such data. The development of the program is contained in the report

  19. Geomagnetic Field During a Reversal

    Science.gov (United States)

    Heirtzler, J. R.

    2003-01-01

    It has frequently been suggested that only the geomagnetic dipole, rather than higher order poles, reverse during a geomagnetic field reversal. Under this assumption the geomagnetic field strength has been calculated for the surface of the Earth for various steps of the reversal process. Even without an eminent a reversal of the field, extrapolation of the present secular change (although problematic) shows that the field strength may become zero in some geographic areas within a few hundred years.

  20. The national geomagnetic initiative

    Science.gov (United States)

    1993-01-01

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

  1. A preliminary comparison of F region plasma drifts and E region irregularity drifts in the auroral zone

    International Nuclear Information System (INIS)

    Ecklund, W.L.; Balsley, B.B.; Carter, D.A.

    1977-01-01

    During several days in April--May 1976 the Chatanika, Alaska, incoherent scatter radar and a temporary Doppler auroral radar located at Aniak, Alaska, were directed toward ionospheric volumes along a common magnetic field line in order to compare E region and F region drifts and associated electric fields. The Chatanika radar measured F region plasma drifts via the incoherent scatter technique, while the Aniak radar measured the drifts of E region irregularities (i.e., the radar aurora). The radar geometry was arranged so that both radars measured approximately the same velocity component of a magnetically westward or eastward motion. Preliminary data show good agreement between the drift velocity components measured by the two techniques during most of the experimental period. This result indicates that relatively modest auroral radar systems may be used, with some qualifications, to determine auroral electric fields

  2. Characteristics of the development of the westward electrojet during the expansive phase of magnetospheric substorms

    International Nuclear Information System (INIS)

    Wiens, R.G.; Rostoker, G.

    1975-01-01

    By use of high-, mid-, and low-latitude magnetograms it is concluded that the westward expansion of the substorm westward electrojet is not continuous but takes place as a series of discrete steps or jumps. The substorm is pictured as consisting of the sequential development of a series of westward electrojets, which we have labeled a 'substorm sequence.' The westward electrojets develop in succession at intervals of about 10 min in such a way that each new electrojet appears to the northwest of the previous one. Associated with the westward jumps of substorm activity are enhancements in the growth rate of a ring or cross-tail current. These enhancements are concurrent with the onset of the westward electrojets and occur to the west of that sector which is presently undergoing its initial onset of substorm activity. Each substorm intensification is accompanied by a response in the adjacent sector to the west, consistent with the signatures of growth suggested by McPherron (1972) and Iijima and Nagata (1972). We suggest that growth may be stimulated by the same mechanism which triggers the expansion phase and that the energy responsible for ensuing substorm intensifications in the evening sector is made available in this fashion

  3. Geomagnetically conjugate observation of plasma bubbles and thermospheric neutral winds at low latitudes

    Science.gov (United States)

    Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Nishioka, M.; Kubota, M.; Tsugawa, T.; Nagatsuma, T.; Komonjinda, S.; Yatini, C. Y.

    2015-03-01

    This is the first paper that reports simultaneous observations of zonal drift of plasma bubbles and the thermospheric neutral winds at geomagnetically conjugate points in both hemispheres. The plasma bubbles were observed in the 630 nm nighttime airglow images taken by using highly sensitive all-sky airglow imagers at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0°S), and Chiang Mai, Thailand (MLAT: 8.9°N), which are nearly geomagnetically conjugate stations, for 7 h from 13 to 20 UT (from 20 to 03 LT) on 5 April 2011. The bubbles continuously propagated eastward with velocities of 100-125 m/s. The 630 nm images at Chiang Mai and those mapped to the conjugate point of Kototabang fit very well, which indicates that the observed plasma bubbles were geomagnetically connected. The eastward thermospheric neutral winds measured by two Fabry-Perot interferometers were 70-130 m/s at Kototabang and 50-90 m/s at Chiang Mai. We compared the observed plasma bubble drift velocity with the velocity calculated from the observed neutral winds and the model conductivity, to investigate the F region dynamo contribution to the bubble drift velocity. The estimated drift velocities were 60-90% of the observed velocities of the plasma bubbles, suggesting that most of the plasma bubble velocity can be explained by the F region dynamo effect.

  4. Geomagnetic Reversals during the Phanerozoic.

    Science.gov (United States)

    McElhinny, M W

    1971-04-09

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

  5. Evolution of the ring current during two geomagnetic storms

    International Nuclear Information System (INIS)

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

    1987-01-01

    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

  6. Increased Arctic sea ice drift alters adult female polar bear movements and energetics.

    Science.gov (United States)

    Durner, George M; Douglas, David C; Albeke, Shannon E; Whiteman, John P; Amstrup, Steven C; Richardson, Evan; Wilson, Ryan R; Ben-David, Merav

    2017-09-01

    Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987-1998 and 1999-2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%-9.6%) or by increasing their travel speed (8.5%-8.9%). This increased their calculated annual energy expenditure by 1.8%-3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1-3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  7. Wintertime westward-traveling planetary-scale perturbations over the Euro-Atlantic region

    Energy Technology Data Exchange (ETDEWEB)

    Doblas-Reyes, F.J. [Centro de Astrobiologia, INTA, Madrid (Spain); Pastor, M.A.; Casado, M.J. [Instituto Nacional de Meteorologia, Madrid (Spain); Deque, M. [CNRM, Meteo-France, Toulouse (France)

    2001-07-01

    The features of the wintertime westward-traveling planetary scale perturbations over the Euro-Atlantic region are examined through the use of space-time spectral analysis applied to the 500 hPa geopotential height field. The intention is to understand the nature of these phenomena and the performance of climate models. Data from both ECMWF re-analyses and a simulation from the ARPEGE general circulation model are used. Westward-traveling planetary scale transients are found over the region as local perturbations resembling Rossby normal modes, with a maximum power over the Eastern Atlantic. The westward-traveling planetary scale transients north of 40 {sup circle} N have periods larger than 20 days. South of this latitude, wave periods are shifted to a band around 10 days, so that they can be related to subtropical transient waves. The atmospheric model used, like other models which exhibit reasonable mean climatic properties, tend to have less overall intraseasonal variability than observed. Nevertheless, the model is able to capture most of the features of the westward-traveling low-frequency transients. The differences in basic state, partially produced by scale interactions, would lead to the generation of westward-traveling waves in the model distinct from the observed. However, it is suggested that the improvement of the present model version with regard to previous model versions is due to a better simulation of the time-mean state. The reasonable simulation of the synoptic-scale variability south of 50 {sup circle} N, and thus of its barotropic forcing on the basic state, may also help to explain the realistic westward-traveling transients in the model. (orig.)

  8. Instability of drift Alfven wave accompanying polar magnetic storm

    International Nuclear Information System (INIS)

    Higuchi, Yoshihiro

    1974-01-01

    As the micro plasma instability due to the plasma non-uniformity in magnetosphere, there is the instability of drift Alfven wave. With the data obtained with the network of multiple observation points for geomagnetism, attempt was made to prove the hypothesis that the instability of drift Alfven wave due to the electron temperature gradient at the inner boundary of plasma sheet may be one of the causes for the geomagnetic pulsation (Pi 1) accompanying polar magnetic storm. Up to date, final conclusion is yet impossible as to the problems in it due to the discussion based on the data from widely separated observation points. The installation of economically efficient multi-point observation network is necessary for the solution. (Mori, K.)

  9. The temporal and spatial variations of low frequency geomagnetic pulsations at polar cusp and cap latitudes

    International Nuclear Information System (INIS)

    Kleimenova, N.; Kozyreva, O.V.; Francia, P.; Villante, U.

    1999-01-01

    Geomagnetic field measurements at two Antarctic are compared during two weeks in the local summer (January 1-15, 1992). Low frequency (0.6 mHz) pulsations are observed at each station near local magnetic noon. The same wave packets appear in some case also at the other station, although with a significant attenuation, more clearly in the morning sector; the wave show a near noon reversal of the polarization sense from counterclockwise in the morning to clockwise in the afternoon indicating a westward and an eastward propagation, respectively

  10. The temporal and spatial variations of low frequency geomagnetic pulsations at polar cusp and cap latitudes

    Directory of Open Access Journals (Sweden)

    J. Bitterly

    1999-06-01

    Full Text Available Geomagnetic field measurements at two Antarctic stations are compared during two weeks in the local summer (January 1-15, 1992. Low frequency (0.6-6 mHz pulsations are observed at each station near local magnetic noon. The same wave packets appear in some cases also at the other station, although with a significant attenuation, more clearly in the morning sector; the waves show a near noon reversal of the polarization sense from counter-clockwise in the morning to clockwise in the afternoon indicating a westward and an eastward propagation, respectively.

  11. The effect of plasma drift on the electromagnetic cyclotron instability

    International Nuclear Information System (INIS)

    Kulkarni, V.H.; Rycroft, M.J.

    1979-01-01

    It is shown that the drift of plasma across a homogeneous magnetic field causes the generation of a wave electric field which, for waves propagating along the magnetic field in the whistler mode, is in the direction of the magnetic field. This leads to Landau damping of the wave field by the background electron distribution, simultaneously with amplification via the electromagnetic cyclotron instability. The drift velocity of the plasma for zero net growth of a whistler mode signal is calculated. It is suggested that such a process occurs in the equatorial region of the magnetosphere during a geomagnetic storm and accounts for the missing band of emissions at half the equatorial gyrofrequency. (Auth.)

  12. The neutral thermosphere at Arecibo during geomagnetic storms

    International Nuclear Information System (INIS)

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

    1991-01-01

    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

  13. Geomagnetic spikes on the core-mantle boundary

    Science.gov (United States)

    Davies, C. J.; Constable, C.

    2017-12-01

    Extreme variations of Earth's magnetic field occurred in the Levantine region around 1000 BC, where the field intensity rose and fell by a factor of 2-3 over a short time and confined spatial region. There is presently no coherent link between this intensity spike and the generating processes in Earth's liquid core. Here we test the attribution of a surface spike to a flux patch visible on the core-mantle boundary (CMB), calculating geometric and energetic bounds on resulting surface geomagnetic features. We show that the Levantine intensity high must span at least 60 degrees in longitude. Models providing the best trade-off between matching surface spike intensity, minimizing L1 and L2 misfit to the available data and satisfying core energy constraints produce CMB spikes 8-22 degrees wide with peak values of O(100) mT. We propose that the Levantine spike grew in place before migrating northward and westward, contributing to the growth of the axial dipole field seen in Holocene field models. Estimates of Ohmic dissipation suggest that diffusive processes, which are often neglected, likely govern the ultimate decay of geomagnetic spikes. Using these results, we search for the presence of spike-like features in geodynamo simulations.

  14. Drift chamber detectors

    International Nuclear Information System (INIS)

    Duran, I.; Martinez Laso, L.

    1989-01-01

    A review of High Energy Physics detectors based on drift chambers is presented. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysied, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author)

  15. Drift Chambers detectors

    International Nuclear Information System (INIS)

    Duran, I.; Martinez laso, L.

    1989-01-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs

  16. Geomagnetic Observatory Database February 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) maintains an active database of worldwide geomagnetic observatory...

  17. Impact of the Lower Atmosphere on the Ionosphere Response to a Geomagnetic Superstorm

    Science.gov (United States)

    Pedatella, N. M.

    2016-12-01

    Numerical simulations in the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) are performed to elucidate the impacts of lower atmosphere forcing on the ionosphere response to a geomagnetic superstorm. In particular, how the ionosphere variability due to the October 2003 Halloween storm would be different if it occurred in January coincident with a major sudden stratosphere warming (SSW) event is investigated. The TIE-GCM simulations reveal that the E x B vertical drift velocity and total electron content (TEC) respond differently to the geomagnetic disturbance when the lower atmosphere forcing is representative of SSW conditions compared to climatological lower atmosphere forcing conditions. Notably, the storm time variations in the E x B vertical drift velocity differ when the effects of the SSW are considered, and this is in part due to effects of the SSW on the equatorial ionosphere being potentially misinterpreted as being of geomagnetic origin. Differences in the TEC response to the geomagnetic storm can be up to 100% ( 30 TECU) of the storm induced TEC change, and the temporal variability of the TEC during the storm recovery phase is considerably different if SSW effects are considered. The results demonstrate that even during periods of extreme geomagnetic forcing it is important to consider the effects of lower atmosphere forcing on the ionosphere variability.

  18. On polar daily geomagnetic variation

    Directory of Open Access Journals (Sweden)

    Paola De Michelis

    2015-11-01

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

  19. Observational evidence for westward propagation of temperature inversions in the southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shankar, D.; Gopalakrishna, V.V.; Shenoi, S.S.C.; Durand, F.; Shetye, S.R.; Rajan, C.K.; Johnson, Z.; Araligidad, N.; Michael, G.S.

    2002 to April 2003 show that temperature inversions occur off the southwest coast of India in early December with the arrival of low-salinity waters from the Bay of Bengal. The low-salinity waters and the inversions propagate westward along...

  20. Westward Extension of the Lionfish Pterois volitans Linnaeus, 1758 along the Mediterranean Coast of Turkey

    Directory of Open Access Journals (Sweden)

    Mehmet Gokoglu

    2017-06-01

    Full Text Available One red lionfish (Pterois volitans was caught in the Gulf of Antalya on October 15th 2016. The present study, seconf record of P. volitans was reported in the coast of the Antalya Bay, Turkey. Our study shows that P. volitans westward extension along to Turkey Mediterranean coasts.

  1. Characterization and demonstration results of a SQUID magnetometer system developed for geomagnetic field measurements

    Science.gov (United States)

    Kawai, J.; Miyamoto, M.; Kawabata, M.; Nosé, M.; Haruta, Y.; Uehara, G.

    2017-08-01

    We characterized a low temperature superconducting quantum interference device (SQUID) magnetometer system developed for high-sensitivity geomagnetic field measurement, and demonstrated the detection of weak geomagnetic signals. The SQUID magnetometer system is comprised of three-axis SQUID magnetometers housed in a glass fiber reinforced plastic cryostat, readout electronics with flux locked loop (FLL), a 24-bit data logger with a global positioning system and batteries. The system noise was approximately 0.2 pT √Hz- 1/2 in the 1-50 Hz frequency range. This performance was determined by including the thermal noise and the shielding effect of the copper shield, which covered the SQUID magnetometers to eliminate high-frequency interference. The temperature drift of the system was ˜0.8 pT °C- 1 in an FLL operation. The system operated for a month using 33 l liquid helium. Using this system, we performed the measurements of geomagnetic field in the open-air, far away from the city. The system could detect weak geomagnetic signals such as the Schumann resonance with sixth harmonics, and the ionospheric Alfvén resonance appearing at night, for the north-south and east-west components of the geomagnetic field. We confirm that the system was capable of high-sensitivity measurement of the weak geomagnetic activities.

  2. Study of the Equatorial and Low-Latitude Electrodynamic and Ionospheric Disturbances During the 22-23 June 2015 Geomagnetic Storm Using Ground-Based and Spaceborne Techniques

    Science.gov (United States)

    Astafyeva, E.; Zakharenkova, I.; Hozumi, K.; Alken, P.; Coïsson, P.; Hairston, M. R.; Coley, W. R.

    2018-03-01

    We use a set of ground-based instruments (Global Positioning System receivers, ionosondes, magnetometers) along with data of multiple satellite missions (Swarm, C/NOFS, DMSP, GUVI) to analyze the equatorial and low-latitude electrodynamic and ionospheric disturbances caused by the geomagnetic storm of 22-23 June 2015, which is the second largest storm in the current solar cycle. Our results show that at the beginning of the storm, the equatorial electrojet (EEJ) and the equatorial zonal electric fields were largely impacted by the prompt penetration electric fields (PPEF). The PPEF were first directed eastward and caused significant ionospheric uplift and positive ionospheric storm on the dayside, and downward drift on the nightside. Furthermore, about 45 min after the storm commencement, the interplanetary magnetic field (IMF) Bz component turned northward, leading to the EEJ changing sign to westward, and to overall decrease of the vertical total electron content (VTEC) and electron density on the dayside. At the end of the main phase of the storm, and with the second long-term IMF Bz southward turn, we observed several oscillations of the EEJ, which led us to conclude that at this stage of the storm, the disturbance dynamo effect was already in effect, competing with the PPEF and reducing it. Our analysis showed no significant upward or downward plasma motion during this period of time; however, the electron density and the VTEC drastically increased on the dayside (over the Asian region). We show that this second positive storm was largely influenced by the disturbed thermospheric conditions.

  3. Dike/Drift Interactions

    Energy Technology Data Exchange (ETDEWEB)

    E. Gaffiney

    2004-11-23

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1).

  4. Dike/Drift Interactions

    International Nuclear Information System (INIS)

    Gaffiney, E.

    2004-01-01

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1)

  5. The Drift Burst Hypothesis

    OpenAIRE

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    2016-01-01

    The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude are an expected and regular occurrence in financial markets that can arise through established mechanisms such as feedback trading. At a theoretical level, we show how to build drift bursts into the...

  6. Rectangular drift tube characteristics

    International Nuclear Information System (INIS)

    Denisov, D.S.; Musienko, Yu.V.

    1985-01-01

    Results on the study of the characteristics of a 50 x 100 mm aluminium drift tube are presented. The tube was filled with argon-methane and argon-isobutane mixtures. With 16 per cent methane concentration the largest deviation from a linear relation between the drift time and the drift path over 50 mm is less than 2 mm. The tube filled with argon-isobutane mixture is capable of operating in a limited streamer mode

  7. Dike/Drift Interactions

    Energy Technology Data Exchange (ETDEWEB)

    E.S. Gaffney

    2003-10-08

    This report documents the model of events associated with a potential intrusion of magma from a volcanic dike into a drift or drifts in the Yucca Mountain Nuclear Waste Repository. The following topics are included in this report: (1) A discussion of dike propagation, which provides the basis for describing the path that a representative dike, or swarm of dikes, would follow during an event. (2) A discussion of magma flow, which evaluates the interaction at the junction of the propagating dike with the drift and the movement of magmatic products into and down drifts and, potentially, through a drift to the surface by way of access drift or a secondary dike opened up along the drift. (3) A discussion of gas flow and conductive cooling of a magma-filled drift, describing how an adjacent drift that has not been intersected by a dike could be affected by post-intrusion phenomena. Note that a gas flow analysis is also addressed in ''Igneous Intrusion Impacts on Waste Form and Waste Packages'' (BSC 2003 [DIRS 161810]), and those results are consistent with the results presented in this report.

  8. Dike/Drift Interactions

    International Nuclear Information System (INIS)

    E.S. Gaffney

    2003-01-01

    This report documents the model of events associated with a potential intrusion of magma from a volcanic dike into a drift or drifts in the Yucca Mountain Nuclear Waste Repository. The following topics are included in this report: (1) A discussion of dike propagation, which provides the basis for describing the path that a representative dike, or swarm of dikes, would follow during an event. (2) A discussion of magma flow, which evaluates the interaction at the junction of the propagating dike with the drift and the movement of magmatic products into and down drifts and, potentially, through a drift to the surface by way of access drift or a secondary dike opened up along the drift. (3) A discussion of gas flow and conductive cooling of a magma-filled drift, describing how an adjacent drift that has not been intersected by a dike could be affected by post-intrusion phenomena. Note that a gas flow analysis is also addressed in ''Igneous Intrusion Impacts on Waste Form and Waste Packages'' (BSC 2003 [DIRS 161810]), and those results are consistent with the results presented in this report

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  10. Six-day westward propagating wave in the maximum electron density of the ionosphere

    Directory of Open Access Journals (Sweden)

    D. Altadill

    2003-07-01

    Full Text Available Analyses of time-spatial variations of critical plasma frequency foF2 during the summer of 1998 reveal the existence of an oscillation activity with attributes of a 6-day westward propagating wave. This event manifests itself as a global scale wave in the foF2 of the Northern Hemisphere, having a zonal wave number 2. This event coincides with a 6-day oscillation activity in the meridional neutral winds of the mesosphere/lower thermosphere (MLT. The oscillation in neutral winds seems to be linked to the 6–7-day global scale unstable mode westward propagating wave number 1 in the MLT. The forcing mechanisms of the 6-day wave event in the ionosphere from the wave activity in the MLT are discussed.Key words. Ionosphere (Ionosphere-Atmosphere interactions; Mid-latitude Ionosphere – Meterology and atmospheric dynamics (waves and tides

  11. Six-day westward propagating wave in the maximum electron density of the ionosphere

    Directory of Open Access Journals (Sweden)

    D. Altadill

    Full Text Available Analyses of time-spatial variations of critical plasma frequency foF2 during the summer of 1998 reveal the existence of an oscillation activity with attributes of a 6-day westward propagating wave. This event manifests itself as a global scale wave in the foF2 of the Northern Hemisphere, having a zonal wave number 2. This event coincides with a 6-day oscillation activity in the meridional neutral winds of the mesosphere/lower thermosphere (MLT. The oscillation in neutral winds seems to be linked to the 6–7-day global scale unstable mode westward propagating wave number 1 in the MLT. The forcing mechanisms of the 6-day wave event in the ionosphere from the wave activity in the MLT are discussed.

    Key words. Ionosphere (Ionosphere-Atmosphere interactions; Mid-latitude Ionosphere – Meterology and atmospheric dynamics (waves and tides

  12. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dwayne C. Kicker

    2001-09-28

    A statistical description of the probable block sizes formed by fractures around the emplacement drifts has been developed for each of the lithologic units of the repository host horizon. A range of drift orientations with the drift azimuth varied in 15{sup o} increments has been considered in the static analysis. For the quasi-static seismic analysis, and the time-dependent and thermal effects analysis, two drift orientations have been considered: a drift azimuth of 105{sup o} and the current emplacement drift azimuth of 75{sup o}. The change in drift profile resulting from progressive deterioration of the emplacement drifts has been assessed both with and without backfill. Drift profiles have been determined for four different time increments, including static (i.e., upon excavation), 200 years, 2,000 years, and 10,000 years. The effect of seismic events on rock fall has been analyzed. Block size distributions and drift profiles have been determined for three seismic levels, including a 1,000-year event, a 5,000-year event, and a 10,000-year event. Data developed in this modeling and analysis activity have been entered into the TDMS (DTN: MO0109RDDAAMRR.003). The following conclusions have resulted from this drift degradation analysis: (1) The available fracture data are suitable for supporting a detailed key block analysis of the repository host horizon rock mass. The available data from the north-south Main Drift and the east-west Cross Drift provide a sufficient representative fracture sample of the repository emplacement drift horizon. However, the Tptpln fracture data are only available from a relatively small section of the Cross Drift, resulting in a smaller fracture sample size compared to the other lithologic units. This results in a lower degree of confidence that the key block data based on the Tptpln data set is actually representative of the overall Tptpln key block population. (2) The seismic effect on the rock fall size distribution for all events

  13. Biological effects of geomagnetic storms

    International Nuclear Information System (INIS)

    Chibisov, S.M.; Breus, T.K.; Levitin, A.E.; Drogova, G.M.; AN SSSR, Moscow; AN SSSR, Moscow

    1995-01-01

    Six physiological parameters of cardio-vascular system of rabbits and ultrastructure of cardiomyocytes were investigated during two planetary geomagnetic storms. At the initial and main phase of the storm the normal circadian structure in each cardiovascular parameter was lost. The disynchronozis was growing together with the storm and abrupt drop of cardia activity was observed during the main phase of storm. The main phase of storm followed by the destruction and degradation of cardiomyocytes. Parameters of cardia activity became substantially synchronized and characterized by circadian rhythm structure while the amplitude of deviations was still significant at the recovery stage of geomagnetic storm. 3 refs.; 7 figs

  14. An electrodeless drift chamber

    International Nuclear Information System (INIS)

    Allison, J.; Barlow, R.J.; Bowdery, C.K.; Duerdoth, I.; Rowe, P.G.

    1982-01-01

    We describe a chamber in which the drift field is controlled by the deposition of electrostatic charge on an insulating surface. The chamber operates with good efficiency and precision for observed drift distances of up to 45 cm, promises to be extremely robust and adaptable and offers a very cheap way of making particle detectors. (orig.)

  15. Modeling concept drift

    DEFF Research Database (Denmark)

    Borchani, Hanen; Martinez, Ana Maria; Masegosa, Andrés R.

    2015-01-01

    An often used approach for detecting and adapting to concept drift when doing classification is to treat the data as i.i.d. and use changes in classification accuracy as an indication of concept drift. In this paper, we take a different perspective and propose a framework, based on probabilistic ...... data set from a Spanish bank....

  16. Estimating Outer Zone Radial Diffusion Coefficients from Drift Scale Fluctuations in Van Allen Particle Data

    Science.gov (United States)

    O'Brien, T. P., III; Claudepierre, S. G.

    2017-12-01

    During geomagnetic storms, the Earth's outer radiation belt experiences enhanced radial transport. This transport occurs via phase-dependent radial displacements of particles, either by impulsive events or drift resonant waves. Because transport is phase dependent, it produces drift phase bunching, which can be observed with in situ particle detectors. We provide bounds on the radial diffusion coefficients derived from this drift phase structure as seen by NASA's Van Allen Probes. We compare these bounds to published radial diffusion coefficient models, particularly those derived independently from electromagnetic field observations.

  17. Time dependent drift Hamiltonian

    International Nuclear Information System (INIS)

    Boozer, A.H.

    1982-04-01

    The motion of individual charged particles in a given magnetic and an electric fields is discussed. An idea of a guiding center distribution function f is introduced. The guiding center distribution function is connected to the asymptotic Hamiltonian through the drift kinetic equation. The general non-stochastic magnetic field can be written in a contravariant and a covariant forms. The drift Hamiltonian is proposed, and the canonical gyroradius is presented. The proposed drift Hamiltonian agrees with Alfven's drift velocity to lowest non-vanishing order in the gyroradius. The relation between the exact, time dependent equations of motion and the guiding center equation is clarified by a Lagrangian analysis. The deduced Lagrangian represents the drift motion. (Kato, T.)

  18. Abstraction of Drift Seepage

    International Nuclear Information System (INIS)

    J.T. Birkholzer

    2004-01-01

    This model report documents the abstraction of drift seepage, conducted to provide seepage-relevant parameters and their probability distributions for use in Total System Performance Assessment for License Application (TSPA-LA). Drift seepage refers to the flow of liquid water into waste emplacement drifts. Water that seeps into drifts may contact waste packages and potentially mobilize radionuclides, and may result in advective transport of radionuclides through breached waste packages [''Risk Information to Support Prioritization of Performance Assessment Models'' (BSC 2003 [DIRS 168796], Section 3.3.2)]. The unsaturated rock layers overlying and hosting the repository form a natural barrier that reduces the amount of water entering emplacement drifts by natural subsurface processes. For example, drift seepage is limited by the capillary barrier forming at the drift crown, which decreases or even eliminates water flow from the unsaturated fractured rock into the drift. During the first few hundred years after waste emplacement, when above-boiling rock temperatures will develop as a result of heat generated by the decay of the radioactive waste, vaporization of percolation water is an additional factor limiting seepage. Estimating the effectiveness of these natural barrier capabilities and predicting the amount of seepage into drifts is an important aspect of assessing the performance of the repository. The TSPA-LA therefore includes a seepage component that calculates the amount of seepage into drifts [''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504], Section 6.3.3.1)]. The TSPA-LA calculation is performed with a probabilistic approach that accounts for the spatial and temporal variability and inherent uncertainty of seepage-relevant properties and processes. Results are used for subsequent TSPA-LA components that may handle, for example, waste package corrosion or radionuclide transport

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

    Science.gov (United States)

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

    2014-10-06

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

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

    Science.gov (United States)

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

    2014-01-01

    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

  1. Mantle superplumes induce geomagnetic superchrons

    Directory of Open Access Journals (Sweden)

    Peter eOlson

    2015-07-01

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

  2. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    G.H. Nieder-Westermann

    2005-01-01

    The outputs from the drift degradation analysis support scientific analyses, models, and design calculations, including the following: (1) Abstraction of Drift Seepage; (2) Seismic Consequence Abstraction; (3) Structural Stability of a Drip Shield Under Quasi-Static Pressure; and (4) Drip Shield Structural Response to Rock Fall. This report has been developed in accordance with ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The drift degradation analysis includes the development and validation of rockfall models that approximate phenomenon associated with various components of rock mass behavior anticipated within the repository horizon. Two drift degradation rockfall models have been developed: the rockfall model for nonlithophysal rock and the rockfall model for lithophysal rock. These models reflect the two distinct types of tuffaceous rock at Yucca Mountain. The output of this modeling and analysis activity documents the expected drift deterioration for drifts constructed in accordance with the repository layout configuration (BSC 2004 [DIRS 172801])

  3. Relation of zonal plasma drift and wind in the equatorial F region as derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    J. Park

    2013-06-01

    Full Text Available In this paper we estimate zonal plasma drift in the equatorial ionospheric F region without counting on ion drift meters. From June 2001 to June 2004 zonal plasma drift velocity is estimated from electron, neutral, and magnetic field observations of Challenging Mini-satellite Payload (CHAMP in the 09:00–20:00 LT sector. The estimated velocities are validated against ion drift measurements by the Republic of China Satellite-1/Ionospheric Plasma and Electrodynamics Instrument (ROCSAT-1/IPEI during the same period. The correlation between the CHAMP (altitude ~ 400 km estimates and ROCSAT-1 (altitude ~ 600 km observations is reasonably high (R ≈ 0.8. The slope of the linear regression is close to unity. However, the maximum westward drift and the westward-to-eastward reversal occur earlier for CHAMP estimates than for ROCSAT-1 measurements. In the equatorial F region both zonal wind and plasma drift have the same direction. Both generate vertical currents but with opposite signs. The wind effect (F region wind dynamo is generally larger in magnitude than the plasma drift effect (Pedersen current generated by vertical E field, thus determining the direction of the F region vertical current.

  4. Analysis of Total Electron Content and Electron Density Profile during Different Geomagnetic Storms

    Science.gov (United States)

    Chapagain, N. P.; Rana, B.; Adhikari, B.

    2017-12-01

    Total Electron content (TEC) and electron density are the key parameters in the mitigation of ionospheric effects on radio communication system. Detail study of the TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (13˚N -17˚N, 88˚E -98˚E), (30˚N-50˚N, 120˚W -95˚W), (29˚S-26˚S, 167˚W-163˚W,) and (60˚S-45˚S, 120˚W-105˚W) using the Gravity Recovery and Climate Experiment (GRACE) satellite observations. In order to find the geomagnetic activity, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma drift velocity (Vsw), flow pressure (nPa), AE, Dst and Kp indices were obtained from Operating Mission as Nodes on the Internet (OMNI) web system. The data for geomagnetic indices have been correlated with the TEC and electron density for four different events of geomagnetic storms on 6 April 2008, 27 March 2008, 4 September 2008, and 11 October 2008. The result illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes. This study illustrates that the values of TEC and the vertical electron density profile are influenced by the solar wind parameters associated with solar activities. The peak values of electron density and TEC increase as the geomagnetic storms become stronger. Similarly, the electron density profile varies with altitudes, which peaks around the altitude range of about 250- 350 km, depending on the strength of geomagnetic storms. The results clearly show that the peak electron density shifted to higher altitude (from about 250 km to 350 km) as the geomagnetic disturbances becomes stronger.

  5. Collisional drift fluids and drift waves

    International Nuclear Information System (INIS)

    Pfirsch, D.; Correa-Restrepo, D.

    1995-05-01

    The usual theoretical description of drift-wave turbulence (considered to be one possible cause of anomalous transport in a plasma), e.g. the Hasegawa-Wakatani theory, makes use of various approximations, the effect of which is extremely difficult to assess. This concerns in particular the conservation laws for energy and momentum. The latter is important as concerns charge separation and resulting electric fields which are possibly related to the L-H transition. Energy conservation is crucial for the stability behaviour; it will be discussed via an example. New collisional multispecies drift-fluid equations were derived by a new method which yields in a transparent way conservation of energy and total angular momentum, and the law for energy dissipation. Both electrostatic and electromagnetic field variations are considered. The method is based primarily on a Lagrangian for dissipationless fluids in drift approximation with isotropic pressures. The dissipative terms are introduced by adding corresponding terms to the ideal equations of motion and of the pressures. The equations of motion, of course, no longer result from a Lagrangian via Hamilton's principle. Their relation to the ideal equations imply, however, also a relation to the ideal Lagrangian of which one can take advantage. Instead of introducing heat conduction one can also assume isothermal behaviour, e.g. T ν (x)=const. Assumptions of this kind are often made in the literature. The new method of introducing dissipation is not restricted to the present kind of theories; it can equally well be applied to theories such as multi-fluid theories without using the drift approximation of the present paper. Linear instability is investigated via energy considerations and the implications of taking ohmic resistivity into account are discussed. (orig./WL)

  6. Ice ages and geomagnetic reversals

    Science.gov (United States)

    Wu, Patrick

    1992-01-01

    There have been speculations on the relationship between climatic cooling and polarity reversals of the earth's magnetic field during the Pleistocene. Two of the common criticisms on this relationship have been the reality of these short duration geomagnetic events and the accuracy of their dates. Champion et al. (1988) have reviewed recent progress in this area. They identified a total of 10 short-duration polarity events in the last 1 Ma and 6 of these events have been found in volcanic rocks, which also have K-Ar dates. Supposing that the speculated relationship between climatic cooling and geomagnetic reversals actually exist, two mechanisms that assume climatic cooling causes short period magnetic reversals will be investigated. These two methods are core-mantle boundary topography and transfer of the rotational energy to the core.

  7. Geomagnetic storm effects on the occurrences of ionospheric irregularities over the African equatorial/low-latitude region

    Science.gov (United States)

    Amaechi, P. O.; Oyeyemi, E. O.; Akala, A. O.

    2018-04-01

    The study investigated the effects of intense geomagnetic storms of 2015 on the occurrences of large scale ionospheric irregularities over the African equatorial/low-latitude region. Four major/intense geomagnetic storms of 2015 were analyzed for this study. These storms occurred on 17th March 2015 (-229 nT), 22nd June 2015 (-204 nT), 7th October 2015 (-124 nT), and 20th December 2015 (-170 nT). Total Electron Content (TEC) data obtained from five African Global Navigation Satellite Systems (GNSS) stations, grouped into eastern and western sectors were used to derive the ionospheric irregularities proxy indices, e.g., rate of change of TEC (ROT), ROT index (ROTI) and ROTI daily average (ROTIAVE). These indices were characterized alongside with the disturbance storm time (Dst), the Y component of the Interplanetary Electric Field (IEFy), polar cap (PC) index and the H component of the Earth's magnetic field from ground-based magnetometers. Irregularities manifested in the form of fluctuations in TEC. Prompt penetration of electric field (PPEF) and disturbance dynamo electric field (DDEF) modulated the behaviour of irregularities during the main and recovery phases of the geomagnetic storms. The effect of electric field over both sectors depends on the local time of southward turning of IMF Bz. Consequently, westward electric field inhibited irregularities during the main phase of March and October 2015 geomagnetic storms, while for the June 2015 storm, eastward electric field triggered weak irregularities over the eastern sector. The effect of electric field on irregularities during December 2015 storm was insignificant. During the recovery phase of the storms, westward DDEF suppressed irregularities.

  8. Drift Scale THM Model

    International Nuclear Information System (INIS)

    Rutqvist, J.

    2004-01-01

    This model report documents the drift scale coupled thermal-hydrological-mechanical (THM) processes model development and presents simulations of the THM behavior in fractured rock close to emplacement drifts. The modeling and analyses are used to evaluate the impact of THM processes on permeability and flow in the near-field of the emplacement drifts. The results from this report are used to assess the importance of THM processes on seepage and support in the model reports ''Seepage Model for PA Including Drift Collapse'' and ''Abstraction of Drift Seepage'', and to support arguments for exclusion of features, events, and processes (FEPs) in the analysis reports ''Features, Events, and Processes in Unsaturated Zone Flow and Transport and Features, Events, and Processes: Disruptive Events''. The total system performance assessment (TSPA) calculations do not use any output from this report. Specifically, the coupled THM process model is applied to simulate the impact of THM processes on hydrologic properties (permeability and capillary strength) and flow in the near-field rock around a heat-releasing emplacement drift. The heat generated by the decay of radioactive waste results in elevated rock temperatures for thousands of years after waste emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, resulting in water redistribution and altered flow paths. These temperatures will also cause thermal expansion of the rock, with the potential of opening or closing fractures and thus changing fracture permeability in the near-field. Understanding the THM coupled processes is important for the performance of the repository because the thermally induced permeability changes potentially effect the magnitude and spatial distribution of percolation flux in the vicinity of the drift, and hence the seepage of water into the drift. This is important because a sufficient amount of water must be available within a

  9. Seismic Evidence of Ancient Westward Residual Slab Subduction Beneath Southern Taiwan

    Directory of Open Access Journals (Sweden)

    Cheng-Horng Lin

    2015-01-01

    Full Text Available The northeastern convergence of the Philippine Sea plate toward the Eurasian plate causes the major western Philippine Sea plate boundary to subduct toward the northwest or west directions. However, this phenomenon is not clearly observed along the plate boundary between Luzon and Taiwan. Careful examination of deep seismicity in the southern Taiwan area from the earthquake catalog reported by the Central Weather Bureau shows two seismic zones dipping toward the opposing directions. The first dips toward the east from the surface down to 150 km in depth, while the second dips westward at depths between 150 and 200 km. These two seismic zones are confirmed further by seismogram observation and modeling results generated by two deep faults in the southern Taiwan area. The eastward seismic zone clearly results from the Eurasia plate subduction along the Manila trench, while a small section of the westward seismic zone might likely be a residual slab from the ancient subducted Philippine Sea plate. Based on the subduction speed obtained from GPS observations and the subducted Eurasian plate geometry, we can further estimate the eastward Eurasian plate subduction started at least 3.35 million years ago. This result is roughly consistent with the volcanic ages (3 - 4 Ma observed in the arc between Luzon and Taiwan.

  10. Geomagnetic effects caused by rocket exhaust jets

    Directory of Open Access Journals (Sweden)

    Lipko Yu.V.

    2016-09-01

    Full Text Available In the space experiment Radar–Progress, we have made 33 series of measurements of geomagnetic variations during ignitions of engines of Progress cargo spacecraft in low Earth orbit. We used magneto-measuring complexes, installed at observatories of the Institute of Solar-Terrestrial Physics of Siberian Branch of the Russian Academy of Sciences, and magnetotelluric equipment of a mobile complex. We assumed that engine running can cause geomagnetic disturbances in field tubes crossed by the spacecraft. When analyzing experimental data, we took into account the following space weather factors: solar wind parameters, total daily mid-latitude geomagnetic activity index Kр, geomagnetic auroral electrojet index AE, global geomagnetic activity. The empirical data we obtained indicate that 18 of the 33 series showed geomagnetic variations with various periods.

  11. Geomagnetic Observations for Main Field Studies

    DEFF Research Database (Denmark)

    Matzka, Jürgen; Chulliat, A.; Mandea, M.

    2010-01-01

    Direct measurements of the geomagnetic field have been made for more than 400 years, beginning with individual determinations of the angle between geographic and magnetic North. This was followed by the start of continuous time series of full vector measurements at geomagnetic observatories...... and the beginning of geomagnetic repeat stations surveys in the 19th century. In the second half of the 20th century, true global coverage with geomagnetic field measurements was accomplished by magnetometer payloads on low-Earth-orbiting satellites. This article describes the procedures and instruments...... for magnetic field measurements on ground and in space and covers geomagnetic observatories, repeat stations, automatic observatories, satellites and historic observations. Special emphasis is laid on the global network of geomagnetic observatories....

  12. Geomagnetic secular variation in India-regional and local features

    International Nuclear Information System (INIS)

    Srivastava, B.J.; Abbas, H.

    1977-01-01

    A study of the secular variation in the geomagnetic elements H, Z, F and D at Colaba (Bombay)-Alibag for the period 1848-1973, has been made. Fifth degree polynomials are fitted to the data of annual mean values of H, Z and F, and third degree to D, and the residuals discussed. The trends are also examined at the six Indian observatories using the data for 1960-1974. The increasing trend of Z at Alibag is found to decrease from about 1937, while that of H and F from 1965 at 20-30 nT/year, it being of the same order at Sabhawala and Hyderabad but smaller at the equatorial stations, particularly for Z component. The westward annual change in D swings eastward again around 1965 at all the Indian stations. This reversal of the secular variation trend in India after 1965 emerges as an important regional feature connected with a southward migration of the dip equator in India from 1968. The secular change in D at Alibag (+0.4'/year) is somewhat anomalous in the sense that it is reduced as compared to Hyderabad and other stations (+1.6'/year), probably due to the local magnetic anomaly of the Deccan lavas, and calls for detailed investigations. (auth.)

  13. The Geomagnetic Field During a Reversal

    Science.gov (United States)

    Heirtzler, James R.

    2003-01-01

    By modifying the IGRF it is possible to learn what may happen to the geomagnetic field during a geomagnetic reversal. If the entire IGRF reverses then the declination and inclination only reverse when the field strength is zero. If only the dipole component of the IGRF reverses a large geomagnetic field remains when the dipole component is zero and he direction of the field at the end of the reversal is not exactly reversed from the directions at the beginning of the reversal.

  14. Relative drift between black aurora and the ionospheric plasma

    Directory of Open Access Journals (Sweden)

    E. M. Blixt

    2005-07-01

    Full Text Available Black auroras are recognized as spatially well-defined regions within uniform diffuse aurora where the optical emission is significantly reduced. Although a well studied phenomenon, there is no generally accepted theory for black auroras. One theory suggests that black regions are formed when energetic magnetospheric electrons no longer have access to the loss cone. If this blocking mechanism drifts with the source electron population in the magnetosphere, black auroras in the ionosphere should drift eastward with a velocity that increases with the energy of the precipitating electrons in the surrounding aurora, since the gradient-B curvature drift is energy dependent. It is the purpose of this paper to test this hypothesis. To do so we have used simultaneous measurements by the European Incoherent Scatter (EISCAT radar and an auroral TV camera at Tromsø, Norway. We have analyzed 8 periods in which a black aurora occurred frequently to determine their relative drift with respect to the ionospheric plasma. The black aurora was found to drift eastward with a velocity of 1.5–4km/s, which is in accordance with earlier observations. However, one case was found where a black patch was moving westward, this being the first report of such behaviour in the literature. In general, the drift was parallel to the ionospheric flow but at a much higher velocity. This suggests that the generating mechanism is not of ionospheric origin. The characteristic energy of the precipitating electron population was estimated through inversion of E-region plasma density profiles. We show that the drift speed of the black patches increased with the energy of the precipitating electrons in a way consistent with the gradient-B curvature drift, suggesting a magnetospheric mechanism for the black aurora. As expected, a comparison of the drift speeds with a rudimentary dipole field model of the gradient-B curvature drift speed only yields order-of-magnitude agreement, which

  15. Analysis of equatorial plasma bubble zonal drift velocities in the Pacific sector by imaging techniques

    Directory of Open Access Journals (Sweden)

    D. Yao

    2007-03-01

    Full Text Available Using 1024 nights of data from 2002–2005 taken by the Cornell Narrow Field Imager (CNFI, we examine equatorial plasma bubble (EPB zonal drift velocity characteristics. CNFI is located at the Maui Space Surveillance Site on the Haleakala Volcano (geographic: 20.71° N, 203.83° E; geomagnetic: 21.03° N, 271.84° E on the island of Maui, Hawaii. The imager is set up to view in a magnetic field-aligned geometry in order to maximize its resolution. We calculate the zonal drift velocities using two methods: a correlation routine and an EPB west-wall intensity gradient tracking routine. These two methods yield sizeable differences in the evenings, suggesting strong pre-local midnight EPB development. An analysis of the drift velocities is also performed based on the three influencing factors of season, geomagnetic activity, and solar activity. In general, our data match published trends and drift characteristics from past studies. However, we find that the drift magnitudes are much lower than results from other imagers at similar latitude sectors but at different longitude sectors, suggesting that zonal drift velocities have a longitudinal dependence.

  16. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    D. Kicker

    2004-01-01

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal stress. (3) The DRKBA

  17. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  18. Spiral silicon drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Lutz, G.; Kemmer, J.; Prechtel, U.; Ziemann, T.

    1988-01-01

    An advanced large area silicon photodiode (and x-ray detector), called Spiral Drift Detector, was designed, produced and tested. The Spiral Detector belongs to the family of silicon drift detectors and is an improvement of the well known Cylindrical Drift Detector. In both detectors, signal electrons created in silicon by fast charged particles or photons are drifting toward a practically point-like collection anode. The capacitance of the anode is therefore kept at the minimum (0.1pF). The concentric rings of the cylindrical detector are replaced by a continuous spiral in the new detector. The spiral geometry detector design leads to a decrease of the detector leakage current. In the spiral detector all electrons generated at the silicon-silicon oxide interface are collected on a guard sink rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease of the leakage current and the very small capacities of the detector anode with a capacitively matched preamplifier may improve the energy resolution of Spiral Drift Detectors operating at room temperature down to about 50 electrons rms. This resolution is in the range attainable at present only by cooled semiconductor detectors. 5 refs., 10 figs

  19. The 2015 Summer Solstice Storm: One of the Major Geomagnetic Storms of Solar Cycle 24 Observed at Ground Level

    Science.gov (United States)

    Augusto, C. R. A.; Navia, C. E.; de Oliveira, M. N.; Nepomuceno, A. A.; Raulin, J. P.; Tueros, E.; de Mendonça, R. R. S.; Fauth, A. C.; Vieira de Souza, H.; Kopenkin, V.; Sinzi, T.

    2018-05-01

    We report on the 22 - 23 June 2015 geomagnetic storm that occurred at the summer solstice. There have been fewer intense geomagnetic storms during the current solar cycle, Solar Cycle 24, than in the previous cycle. This situation changed after mid-June 2015, when one of the largest solar active regions (AR 12371) of Solar Cycle 24 that was located close to the central meridian, produced several coronal mass ejections (CMEs) associated with M-class flares. The impact of these CMEs on the Earth's magnetosphere resulted in a moderate to severe G4-class geomagnetic storm on 22 - 23 June 2015 and a G2 (moderate) geomagnetic storm on 24 June. The G4 solstice storm was the second largest (so far) geomagnetic storm of Cycle 24. We highlight the ground-level observations made with the New-Tupi, Muonca, and the CARPET El Leoncito cosmic-ray detectors that are located within the South Atlantic Anomaly (SAA) region. These observations are studied in correlation with data obtained by space-borne detectors (ACE, GOES, SDO, and SOHO) and other ground-based experiments. The CME designations are taken from the Computer Aided CME Tracking (CACTus) automated catalog. As expected, Forbush decreases (FD) associated with the passing CMEs were recorded by these detectors. We note a peculiar feature linked to a severe geomagnetic storm event. The 21 June 2015 CME 0091 (CACTus CME catalog number) was likely associated with the 22 June summer solstice FD event. The angular width of CME 0091 was very narrow and measured {˜} 56° degrees seen from Earth. In most cases, only CME halos and partial halos lead to severe geomagnetic storms. We perform a cross-check analysis of the FD events detected during the rise phase of Solar Cycle 24, the geomagnetic parameters, and the CACTus CME catalog. Our study suggests that narrow angular-width CMEs that erupt in a westward direction from the Sun-Earth line can lead to moderate and severe geomagnetic storms. We also report on the strong solar proton

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

    Science.gov (United States)

    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.

  1. Radial semiconductor drift chambers

    International Nuclear Information System (INIS)

    Rawlings, K.J.

    1987-01-01

    The conditions under which the energy resolution of a radial semiconductor drift chamber based detector system becomes dominated by the step noise from the detector dark current have been investigated. To minimise the drift chamber dark current attention should be paid to carrier generation at Si/SiO 2 interfaces. This consideration conflicts with the desire to reduce the signal risetime: a higher drift field for shorter signal pulses requires a larger area of SiO 2 . Calculations for the single shaping and pseudo Gaussian passive filters indicate that for the same degree of signal risetime sensitivity in a system dominated by the step noise from the detector dark current, the pseudo Gaussian filter gives only a 3% improvement in signal/noise and 12% improvement in rate capability compared with the single shaper performance. (orig.)

  2. Nonlinear drift tearing mode

    International Nuclear Information System (INIS)

    Zelenyj, L.M.; Kuznetsova, M.M.

    1989-01-01

    Nonlinear study of magnetic perturbation development under single-mode conditions in collision-free plasma in configurations with the magnetic field shear is investigated. Results are obtained with regard of transverse component of electrical field and its effect on ion dynamics within wide range of ion Larmor radius value and values of magnetic field shear. Increments of nonlinear drift tearing mode are obtained and it is shown that excitation drastic conditions of even linearly stable modes are possible. Mechanism of instability nonlinear stabilization is considered and the value of magnetic island at the saturation threshold is estimeted. Energy of nonlinear drift tearing mode is discussed

  3. The Drift Burst Hypothesis

    DEFF Research Database (Denmark)

    Christensen, Kim; Oomen, Roel; Renò, Roberto

    are an expected and regular occurrence in financial markets that can arise through established mechanisms such as feedback trading. At a theoretical level, we show how to build drift bursts into the continuous-time Itô semi-martingale model in such a way that the fundamental arbitrage-free property is preserved......, currencies and commodities. We find that the majority of identified drift bursts are accompanied by strong price reversals and these can therefore be regarded as “flash crashes” that span brief periods of severe market disruption without any material longer term price impacts....

  4. The Sidebands of the Equatorial Electrojet: General Characteristic of the Westward Currents, as Deduced From CHAMP

    Science.gov (United States)

    Zhou, Yun-Liang; Lühr, Hermann; Alken, Patrick

    2018-02-01

    Based on 5 years (2001-2005) of magnetic field measurements made by the CHAMP satellite, latitudinal profiles of the equatorial electrojet (EEJ) have been derived. This study provides a comprehensive characterization of the reverse current EEJ sidebands. These westward currents peak at ±5° quasi-dipole latitude with typical amplitudes of 35% of the main EEJ. The diurnal amplitude variation is quite comparable with that of the EEJ. Similarly to the EEJ, the intensity is increasing with solar EUV flux, but with a steeper slope, indicating that not only the conductivity plays a role. For the longitude distribution we find, in general, larger amplitudes in the Western than in the Eastern Hemisphere. It is presently a common understanding that the reverse current EEJ sidebands are generated by eastward zonal winds at altitudes above about 120 km. In particular, a positive vertical gradient of wind speed generates westward currents at magnetic latitudes outside of 2° dip latitude. Interesting information about these features can be deduced from the sidebands' tidal characteristics. The longitudinal variation of the amplitude is dominated by a wave-1 pattern, which can primarily be attributed to the tidal components SPW1 and SW3. In case of the hemispheric amplitude differences these same two wave-1 components dominate. The ratio between sideband amplitude and main EEJ is largely controlled by the tidal features of the EEJ. The longitudinal patterns of the latitude, where the sidebands peak, resemble to some extent those of the amplitude. Current densities become larger when the peaks move closer to the magnetic equator.

  5. Evidence for geomagnetic imprinting as a homing mechanism in Pacific salmon.

    Science.gov (United States)

    Putman, Nathan F; Lohmann, Kenneth J; Putman, Emily M; Quinn, Thomas P; Klimley, A Peter; Noakes, David L G

    2013-02-18

    In the final phase of their spawning migration, Pacific salmon use chemical cues to identify their home river, but how they navigate from the open ocean to the correct coastal area has remained enigmatic. To test the hypothesis that salmon imprint on the magnetic field that exists where they first enter the sea and later seek the same field upon return, we analyzed a 56-year fisheries data set on Fraser River sockeye salmon, which must detour around Vancouver Island to approach the river through either a northern or southern passageway. We found that the proportion of salmon using each route was predicted by geomagnetic field drift: the more the field at a passage entrance diverged from the field at the river mouth, the fewer fish used the passage. We also found that more fish used the northern passage in years with warmer sea surface temperature (presumably because fish were constrained to more northern latitudes). Field drift accounted for 16% of the variation in migratory route used, temperature 22%, and the interaction between these variables 28%. These results provide the first empirical evidence of geomagnetic imprinting in any species and imply that forecasting salmon movements is possible using geomagnetic models. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Tapping with intentional drift

    NARCIS (Netherlands)

    Vardy, A.N.; Daffertshofer, A.; Beek, P.J.

    2009-01-01

    When tapping a desired frequency, subjects tend to drift away from this target frequency. This compromises the estimate of the correlation between inter-tap intervals (ITIs) as predicted by the two-level model of Wing and Kristofferson which consists of an internal timer ('clock') and motor delays.

  7. The KLOE drift chamber

    International Nuclear Information System (INIS)

    Ferrari, A.

    2002-01-01

    The design and construction of the large drift chamber of the KLOE experiment is presented. The track reconstruction is described, together with the calibration method and the monitoring systems. The stability of operation and the performance are studied with samples of e + e - , K S K L and K + K - events

  8. High resolution drift chambers

    International Nuclear Information System (INIS)

    Va'vra, J.

    1985-07-01

    High precision drift chambers capable of achieving less than or equal to 50 μm resolutions are discussed. In particular, we compare so called cool and hot gases, various charge collection geometries, several timing techniques and we also discuss some systematic problems. We also present what we would consider an ''ultimate'' design of the vertex chamber. 50 refs., 36 figs., 6 tabs

  9. Argus drift chamber

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, M; Nagovizin, V; Hasemann, H; Michel, E; Schmidt-Parzefall, W; Wurth, R; Kim, P

    1983-11-15

    The ARGUS detector came into operation at the DORIS-II e/sup +/s/sup -/ storage ring at the end of 1982. Its two meter long drift chamber contains 5940 sense and 24588 field wires organized in uniform 18x18.8 mm/sup 2/ drift cells filling the whole volume. These cells form 36 layers, 18 of which provide stereo views. Each sense wire is equipped with a single hit TDC and ADC for coordinate and dE/dx measurements. The chamber is operated with propane to improve momentum and dE/dx resolution. The drift chamber design and initial performance are presented. With a very crude space-time relation approximation and without all the necessary corrections applied a spatial resolution of about 200 ..mu..m was obtained for half of the drift cell volume. Further corrections should improve this result. An intrinsic dE/dx resolution of 4.2% and an actual resolution of 5% were obtained for cosmic muons and also for Bhabha scattered electrons. An actual dE/dx resolution of 5.6% was obtained for pions from e/sup +/e/sup -/ annihilation data with almost no track selection. A relativistic rise of 30% was observed in good agreement with theory. The long-term stability is still to be investigated.

  10. Inland drift sand landscapes

    NARCIS (Netherlands)

    Fanta, J.; Siepel, H.

    2010-01-01

    Man has had a complex relationship with inland drift sands through the ages. For some centuries these landscapes were seen as a threat to society, especially agriculture and housing. At present we conserve these landscapes as important Natura 2000 priority habitats. In this book you may find these

  11. Guiding center drift equations

    International Nuclear Information System (INIS)

    Boozer, A.H.

    1979-03-01

    The quations for particle guiding center drift orbits are given in a new magnetic coordinate system. This form of the equations not only separates the fast motion along the lines from the slow motion across, but also requires less information about the magnetic field than many other formulations of the problem

  12. IN DRIFT CORROSION PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley

    1999-12-02

    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  13. VLF Wave Properties During Geomagnetic Storms

    Science.gov (United States)

    Blancarte, J.; Artemyev, A.; Mozer, F.; Agapitov, O. V.

    2017-12-01

    Whistler-mode chorus is important for the global dynamics of the inner magnetosphere electron population due to its ability to scatter and accelerate electrons of a wide energy range in the outer radiation belt. The parameters of these VLF emissions change dynamically during geomagnetic storms. Presented is an analysis of four years of Van Allen probe data, utilizing electric and magnetic field in the VLF range focused on the dynamics of chorus wave properties during the enhancement of geomagnetic activity. It is found that VLF emissions respond to geomagnetic storms in more complicated ways than just by affecting the waves' amplitude growth or depletion. Oblique wave amplitudes grow together with parallel waves during periods of intermediate geomagnetic activity, while the occurrence rate of oblique waves decreases during larger geomagnetic storms.

  14. Daily variation characteristics at polar geomagnetic observatories

    Science.gov (United States)

    Lepidi, S.; Cafarella, L.; Pietrolungo, M.; Di Mauro, D.

    2011-08-01

    This paper is based on the statistical analysis of the diurnal variation as observed at six polar geomagnetic observatories, three in the Northern and three in the Southern hemisphere. Data are for 2006, a year of low geomagnetic activity. We compared the Italian observatory Mario Zucchelli Station (TNB; corrected geomagnetic latitude: 80.0°S), the French-Italian observatory Dome C (DMC; 88.9°S), the French observatory Dumont D'Urville (DRV; 80.4°S) and the three Canadian observatories, Resolute Bay (RES; 83.0°N), Cambridge Bay (CBB; 77.0°N) and Alert (ALE, 87.2°N). The aim of this work was to highlight analogies and differences in daily variation as observed at the different observatories during low geomagnetic activity year, also considering Interplanetary Magnetic Field conditions and geomagnetic indices.

  15. Dike Propagation Near Drifts

    International Nuclear Information System (INIS)

    2002-01-01

    The purpose of this Analysis and Model Report (AMR) supporting the Site Recommendation/License Application (SR/LA) for the Yucca Mountain Project is the development of elementary analyses of the interactions of a hypothetical dike with a repository drift (i.e., tunnel) and with the drift contents at the potential Yucca Mountain repository. This effort is intended to support the analysis of disruptive events for Total System Performance Assessment (TSPA). This AMR supports the Process Model Report (PMR) on disruptive events (CRWMS M and O 2000a). This purpose is documented in the development plan (DP) ''Coordinate Modeling of Dike Propagation Near Drifts Consequences for TSPA-SR/LA'' (CRWMS M and O 2000b). Evaluation of that Development Plan and the work to be conducted to prepare Interim Change Notice (ICN) 1 of this report, which now includes the design option of ''Open'' drifts, indicated that no revision to that DP was needed. These analyses are intended to provide reasonable bounds for a number of expected effects: (1) Temperature changes to the waste package from exposure to magma; (2) The gas flow available to degrade waste containers during the intrusion; (3) Movement of the waste package as it is displaced by the gas, pyroclasts and magma from the intruding dike (the number of packages damaged); (4) Movement of the backfill (Backfill is treated here as a design option); (5) The nature of the mechanics of the dike/drift interaction. These analyses serve two objectives: to provide preliminary analyses needed to support evaluation of the consequences of an intrusive event and to provide a basis for addressing some of the concerns of the Nuclear Regulatory Commission (NRC) expressed in the Igneous Activity Issue Resolution Status Report

  16. The South Atlantic Anomaly: the key for a possible geomagnetic reversal

    Directory of Open Access Journals (Sweden)

    F. Javier ePavón-Carrasco

    2016-04-01

    Full Text Available The South Atlantic Anomaly is nowadays one of the most important features of the Earth’s magnetic field. Its extent area at the Earth’s surface is continuously growing since the intensity instrumental measurements are available covering part of the Southern Hemisphere and centred in South America. Several studies associate this anomaly as an indicator of an upcoming geomagnetic transition, such an excursion or reversal. In this paper we carry out a detailed study about this issue using the most recent models that also include data from the last ESA mission Swarm. Our results reveal that one of the reversed polarity patch located under the South Atlantic Ocean is growing with a pronounced rate of -2.54•105 nT per century and with western drift. In addition, we demonstrate that the quadrupole field mainly controls this reversal patch at the CMB along with the rapid decay of the dipolar field. The presence of the reversal patches at the CMB seems to be characteristic during the preparation phase of a geomagnetic transition. However, the present value of the dipolar moment (7.7 1022A•m2 is not so low when compared with recent paleomagnetic data for the Holocene (last 12ka and for the entire Brunhes geomagnetic normal polarity (last 0.8 Ma, although the rate of decay is similar of the previous documented geomagnetic reversals or excursions.

  17. Thermospheric response observed over Fritz peak, Colorado, during two large geomagnetic storms near solar cycle maximum

    International Nuclear Information System (INIS)

    Hernandez, G.; Roble, R.G.; Ridley, E.C.; Allen, J.H.

    1982-01-01

    Nightime thermospheric winds and temperatures have been measured over Fritz Peak Observatory, Colorado (39.9 0 N, 105.5 0 W), with a high resolution Fabry-Perot spectrometer. The winds and temperatures are obtained from the Doppler shifts and line profiles of the (O 1) 15,867K (630 nm) line emission. Measurements made during two large geomagnetic storm periods near solar cycle maximum reveal a thermospheric response to the heat and momentum sources associated with these storms that is more complex than the ones measured near solar cycle minimum. In the earlier measurements made during solar cycle minimum, the winds to the north of Fritz Peak Observatory had an enhanced equatorward component and the winds to the south were also equatorward, usually with smaller velocities. The winds measured to the east and west of the observatory both had an enhanced westward wind component. For the two large storms near the present solar cycle maximum period converging winds are observed in each of the cardinal directions from Fritz Peak Observatory. These converging winds with speeds of hundreds of meters per second last for several hours. The measured neutral gas temperature in each of the directions also increases several hundred degrees Kelvin. Numerical experiments done with the NCAR thermospheric general circulation model (TGCM) suggest that the winds to the east and north of the station are driven by high-latitude heating and enhanced westward ion drag associated with magnetospheric convection. The cause of the enhanced poleward and eastward winds measured to the south and west of Fritz Peak Observatory, respectively, is not known. During geomagnetic quiet conditions the circulation is typically from the soutwest toward the northeast in the evening hours

  18. Style drift in private equity

    NARCIS (Netherlands)

    Cumming, D.; Fleming, G.; Schwienbacher, A.

    2009-01-01

    We introduce the concept of style drift to private equity investment. We present theory and evidence pertaining to style drifts in terms of a fund manager's stated focus on particular stages of entrepreneurial development. We develop a model that derives conditions under which style drifts are less

  19. Vertical slab sinking and westward subduction offshore of Mesozoic North America

    Science.gov (United States)

    Sigloch, Karin; Mihalynuk, Mitchell G.

    2013-04-01

    Subducted slabs in the mantle, as imaged by seismic tomography, preserve a record of ancient subduction zones. Ongoing debate concerns how direct this link is. How long ago did each parcel of slab subduct, and where was the trench located relative to the imaged slab position? Resolving these questions will benefit paleogeographic reconstructions, and restrict the range of plausible rheologies for mantle convection simulations. We investigate one of the largest and best-constrained Mesozoic slab complexes, the "Farallon" in the transition zone and lower mantle beneath North America. We quantitatively integrate observations from whole-mantle P-wave tomography, global plate reconstructions, and land geological evidence from the North American Cordillera. These three data sets permit us to test the simplest conceivable hypothesis for linking slabs to paleo-trenches: that each parcel of slab sank only vertically shortly after entering the trench That is, we test whether within the limits of tomographic resolution, all slab material lies directly below the location where it subducted beneath its corresponding arc. Crucially and in contrast to previous studies, we do not accept or impose an Andean-style west coast trench (Farallon-beneath-continent subduction) since Jurassic times, as this scenario is inconsistent with many geological observations. Slab geometry alone suggests that trenches started out as intra-oceanic because tomography images massive, linear slab "walls" in the lower mantle, extending almost vertically from about 800 km to 2000+ km depth. Such steep geometries would be expected from slabs sinking vertically beneath trenches that were quasi-stationary over many tens of millions of years. Intra-oceanic trenches west of Mesozoic North America could have been stationary, whereas a coastal Farallon trench could not, because the continent moved westward continuously as the Atlantic opened. Overlap of North American west-coast positions, as reconstructed in a

  20. Time variations in geomagnetic intensity

    Science.gov (United States)

    Valet, Jean-Pierre

    2003-03-01

    After many years spent by paleomagnetists studying the directional behavior of the Earth's magnetic field at all possible timescales, detailed measurements of field intensity are now needed to document the variations of the entire vector and to analyze the time evolution of the field components. A significant step has been achieved by combining intensity records derived from archeological materials and from lava flows in order to extract the global field changes over the past 12 kyr. A second significant step was due to the emergence of coherent records of relative paleointensity using the remanent magnetization of sediments to retrace the evolution of the dipole field. A third step was the juxtaposition of these signals with those derived from cosmogenic isotopes. Contemporaneous with the acquisition of records, new techniques have been developed to constrain the geomagnetic origin of the signals. Much activity has also been devoted to improving the quality of determinations of absolute paleointensity from volcanic rocks with new materials, proper selection of samples, and investigations of complex changes in magnetization during laboratory experiments. Altogether these developments brought us from a situation where the field changes were restricted to the past 40 kyr to the emergence of a coherent picture of the changes in the geomagnetic dipole moment for at least the past 1 Myr. On longer timescales the field variability and its average behavior is relatively well documented for the past 400 Myr. Section 3 gives a summary of most methods and techniques that are presently used to track the field intensity changes in the past. In each case, current limits and potential promises are discussed. The section 4 describes the field variations measured so far over various timescales covered by the archeomagnetic and the paleomagnetic records. Preference has always been given to composite records and databases in order to extract and discuss major and global geomagnetic

  1. Diogene pictorial drift chamber

    International Nuclear Information System (INIS)

    Gosset, J.

    1984-01-01

    A pictorial drift chamber, called DIOGENE, has been installed at Saturne in order to study central collisions of high energy heavy ions. It has been adapted from the JADE internal detector, with two major differences to be taken into account. First, the center-of-mass of these collisions is not identical to the laboratory reference frame. Second, the energy loss and the momentum ranges of the particles to be detected are different from the ones in JADE. It was also tried to keep the cost as small as possible, hence the choice of minimum size and minimum number of sensitive wires. Moreover the wire planes are shifted from the beam axis: this trick helps very much to quickly reject the bad tracks caused by the ambiguity of measuring drift distances (positive or negative) through times (always positive)

  2. Drift-Diffusion Equation

    Directory of Open Access Journals (Sweden)

    K. Banoo

    1998-01-01

    equation in the discrete momentum space. This is shown to be similar to the conventional drift-diffusion equation except that it is a more rigorous solution to the Boltzmann equation because the current and carrier densities are resolved into M×1 vectors, where M is the number of modes in the discrete momentum space. The mobility and diffusion coefficient become M×M matrices which connect the M momentum space modes. This approach is demonstrated by simulating electron transport in bulk silicon.

  3. Negative Drift in Populations

    DEFF Research Database (Denmark)

    Lehre, Per Kristian

    2011-01-01

    An important step in gaining a better understanding of the stochastic dynamics of evolving populations, is the development of appropriate analytical tools. We present a new drift theorem for populations that allows properties of their long-term behaviour, e.g. the runtime of evolutionary algorithms......, to be derived from simple conditions on the one-step behaviour of their variation operators and selection mechanisms....

  4. An auroral westward flow channel (AWFC and its relationship to field-aligned current, ring current, and plasmapause location determined using multiple spacecraft observations

    Directory of Open Access Journals (Sweden)

    M. L. Parkinson

    2007-02-01

    Full Text Available An auroral westward flow channel (AWFC is a latitudinally narrow channel of unstable F-region plasma with intense westward drift in the dusk-to-midnight sector ionosphere. AWFCs tend to overlap the equatorward edge of the auroral oval, and their life cycle is often synchronised to that of substorms: they commence close to substorm expansion phase onset, intensify during the expansion phase, and then decay during the recovery phase. Here we define for the first time the relationship between an AWFC, large-scale field-aligned current (FAC, the ring current, and plasmapause location. The Tasman International Geospace Environment Radar (TIGER, a Southern Hemisphere HF SuperDARN radar, observed a jet-like AWFC during ~08:35 to 13:28 UT on 7 April 2001. The initiation of the AWFC was preceded by a band of equatorward expanding ionospheric scatter (BEES which conveyed an intense poleward electric field through the inner plasma sheet. Unlike previous AWFCs, this event was not associated with a distinct substorm surge; rather it occurred during an interval of persistent, moderate magnetic activity characterised by AL~−200 nT. The four Cluster spacecraft had perigees within the dusk sector plasmasphere, and their trajectories were magnetically conjugate to the radar observations. The Waves of High frequency and Sounder for Probing Electron density by Relaxation (WHISPER instruments on board Cluster were used to identify the plasmapause location. The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE EUV experiment also provided global-scale observations of the plasmapause. The Cluster fluxgate magnetometers (FGM provided successive measurements specifying the relative location of the ring current and filamentary plasma sheet current. An analysis of Iridium spacecraft magnetometer measurements provided estimates of large-scale ionospheric FAC in relation to the AWFC evolution. Peak flows in the AWFC were located close to the peak of a Region 2

  5. Kinematic reversal schemes for the geomagnetic dipole.

    Science.gov (United States)

    Levy, E. H.

    1972-01-01

    Fluctuations in the distribution of cyclonic convective cells, in the earth's core, can reverse the sign of the geomagnetic field. Two kinematic reversal schemes are discussed. In the first scheme, a field maintained by cyclones concentrated at low latitude is reversed by a burst of cyclones at high latitude. Conversely, in the second scheme, a field maintained predominantly by cyclones in high latitudes is reversed by a fluctuation consisting of a burst of cyclonic convection at low latitude. The precise fluid motions which produce the geomagnetic field are not known. However, it appears that, whatever the details are, a fluctuation in the distribution of cyclonic cells over latitude can cause a geomagnetic reversal.

  6. Consistent guiding center drift theories

    International Nuclear Information System (INIS)

    Wimmel, H.K.

    1982-04-01

    Various guiding-center drift theories are presented that are optimized in respect of consistency. They satisfy exact energy conservation theorems (in time-independent fields), Liouville's theorems, and appropriate power balance equations. A theoretical framework is given that allows direct and exact derivation of associated drift-kinetic equations from the respective guiding-center drift-orbit theories. These drift-kinetic equations are listed. Northrop's non-optimized theory is discussed for reference, and internal consistency relations of G.C. drift theories are presented. (orig.)

  7. Laboratory Course on Drift Chambers

    International Nuclear Information System (INIS)

    Garcia-Ferreira, Ix-B.; Garcia-Herrera, J.; Villasenor, L.

    2006-01-01

    Drift chambers play an important role in particle physics experiments as tracking detectors. We started this laboratory course with a brief review of the theoretical background and then moved on to the the experimental setup which consisted of a single-sided, single-cell drift chamber. We also used a plastic scintillator paddle, standard P-10 gas mixture (90% Ar, 10% CH4) and a collimated 90Sr source. During the laboratory session the students performend measurements of the following quantities: a) drift velocities and their variations as function of the drift field; b) gas gains and c) diffusion of electrons as they drifted in the gas

  8. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independent...... tensor elements. Furthermore, in current free regions the magnetic gradient tensor becomes symmetric, further reducing the number of independent elements to five. In that case B is a Laplacian potential field and the gradient tensor can be expressed in series of spherical harmonics. We present properties...... of the magnetic gradient tensor and provide explicit expressions of its elements in terms of spherical harmonics. Finally we discuss the benefit of using gradient measurements for exploring the Earth’s magnetic field from space, in particular the advantage of the various tensor elements for a better determination...

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

    Directory of Open Access Journals (Sweden)

    J. L. Zerbo

    2012-02-01

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

  10. The impact of coronal mass ejection on the horizontal geomagnetic fields and the induced geoelectric fields

    Science.gov (United States)

    Falayi, E. O.; Adebesin, B. O.; Bolaji, O. S.

    2018-02-01

    This work investigates the influence of coronal mass ejection (CME) on the time derivatives of horizontal geomagnetic and geoelectric fields, proxy parameters for identifying GICs. 16 events were identified for the year 2003 from the CORONAS-PHOTON spacecraft. Five of the events (May 29, June 9, October 28, October 29, and November 4) were extensively discussed over four magnetic observatories, were analyzed using the time derivatives of the horizontal geomagnetic (dH/dt) and geoelectric (EH) fields obtained from data of the INTERMAGNET network. It was observed that energy distributions of the wavelet power spectrum of the horizontal geoelectric field are noticed at the nighttime on both 29 May and 9 June 2003 across the stations. Daytime and nighttime intensification of energy distribution of the wavelet power spectrum of the horizontal geoelectric field are observed on both 28 and 29 October 2003 due to strong westward electrojet. The 4 November 2003 event depicts daytime amplification of energy distributions of the wavelet power spectrum across the stations. The highest correlation magnitude is obtained in the event of 4 November 2003 between dH/dt and EH relationships during the intense solar flare of class X 17.4. We observed that the correlation magnitude between dH/dt and EH increases with increase in CME activity. We concluded that the response of the surface impedance model for different stations plays a key role in determining the surface electric field strength, due to large electric field changes at different stations.

  11. Geomagnetism solid Earth and upper atmosphere perspectives

    CERN Document Server

    Basavaiah, Nathani

    2011-01-01

    This volume elaborates several important aspects of solid Earth geomagnetism. It covers all the basics of the subject, including biomagnetism and instrumentation, and offers a number of practical applications with carefully selected examples and illustrations.

  12. Magnetotactic bacteria at the geomagnetic equator

    International Nuclear Information System (INIS)

    Frankel, R.B.; Blakemore, R.P.; Araujo, F.F.T. de; Esquivel, D.M.S.; Danon, J.

    1981-01-01

    Magnetotatic bacteria are observed in freshwater and marine sediments of Fortaleza, Brazil, situated close to the geomagnetic equator. Both South-seeking and North-seeking bacteria are present in roughly equal numbers in the same samples. This observation is consistent with the hypothesis that the vertical component of the geomagnetic field selects the predominant polarity type among magnetotactic bacteria in natural environments. (Author) [pt

  13. Toward a possible next geomagnetic transition?

    OpenAIRE

    A. De Santis; E. Qamili; L. Wu

    2013-01-01

    The geomagnetic field is subject to possible reversals or excursions of polarity during its temporal evolution. Considering that: (a) the typical average time between one reversal and the next (the so-called chron) is around 300 000 yr, (b) the last reversal occurred around 780 000 yr ago, (c) more excursions (rapid changes of polarity) can occur within the same chron and (d) the geomagnetic field dipole is currently decreasing, a possible imminent geomagne...

  14. How the geomagnetic field vector reverses polarity

    Science.gov (United States)

    Prevot, M.; Mankinen, E.A.; Gromme, C.S.; Coe, R.S.

    1985-01-01

    A highly detailed record of both the direction and intensity of the Earth's magnetic field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals. ?? 1985 Nature Publishing Group.

  15. Drifting black aurorae?

    International Nuclear Information System (INIS)

    Schoute-Vanneck, H.; Scourfield, M.W.J.; Nielsen, E.

    1990-01-01

    Characteristics of eastward drifting forms, previously described in the literature as black aurorae, have been identified in low-light level TV camera data. The TV field of view was within the field of view of STARE and that of an all-sky camera. On the basis of these observations the authors propose that these auroral forms are a manifestation of folds or waves on the borders of auroral bands propagating along the dark regions between neighboring auroral bands. Conditions under which the folds or waves occur are compatible with their formation by the Kelvin-Helmholtz electrostatic instability

  16. ABSTRACTION OF DRIFT SEEPAGE

    International Nuclear Information System (INIS)

    Wilson, Michael L.

    2001-01-01

    Drift seepage refers to flow of liquid water into repository emplacement drifts, where it can potentially contribute to degradation of the engineered systems and release and transport of radionuclides within the drifts. Because of these important effects, seepage into emplacement drifts is listed as a ''principal factor for the postclosure safety case'' in the screening criteria for grading of data in Attachment 1 of AP-3.15Q, Rev. 2, ''Managing Technical Product Inputs''. Abstraction refers to distillation of the essential components of a process model into a form suitable for use in total-system performance assessment (TSPA). Thus, the purpose of this analysis/model is to put the information generated by the seepage process modeling in a form appropriate for use in the TSPA for the Site Recommendation. This report also supports the Unsaturated-Zone Flow and Transport Process Model Report. The scope of the work is discussed below. This analysis/model is governed by the ''Technical Work Plan for Unsaturated Zone Flow and Transport Process Model Report'' (CRWMS MandO 2000a). Details of this activity are in Addendum A of the technical work plan. The original Work Direction and Planning Document is included as Attachment 7 of Addendum A. Note that the Work Direction and Planning Document contains tasks identified for both Performance Assessment Operations (PAO) and Natural Environment Program Operations (NEPO). Only the PAO tasks are documented here. The planning for the NEPO activities is now in Addendum D of the same technical work plan and the work is documented in a separate report (CRWMS MandO 2000b). The Project has been reorganized since the document was written. The responsible organizations in the new structure are the Performance Assessment Department and the Unsaturated Zone Department, respectively. The work plan for the seepage abstraction calls for determining an appropriate abstraction methodology, determining uncertainties in seepage, and providing

  17. Drift velocity monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2010-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented.

  18. The CLEO III drift chamber

    CERN Document Server

    Peterson, D; Briere, R A; Chen, G; Cronin-Hennessy, D; Csorna, S; Dickson, M; Dombrowski, S V; Ecklund, K M; Lyon, A; Marka, S; Meyer, T O; Patterson, J R; Sadoff, A; Thies, P; Thorndike, E H; Urner, D

    2002-01-01

    The CLEO group at the Cornell Electron Storage Ring has constructed and commissioned a new central drift chamber. With 9796 cells arranged in 47 layers ranging in radius from 13.2 to 79 cm, the new drift chamber has a smaller outer radius and fewer wires than the drift chamber it replaces, but allows the CLEO tracking system to have improved momentum resolution. Reduced scattering material in the chamber gas and in the inner skin separating the drift chamber from the silicon vertex detector provides a reduction of the multiple scattering component of the momentum resolution and an extension of the usable measurement length into the silicon. Momentum resolution is further improved through quality control in wire positioning and symmetry of the electric fields in the drift cells which have provided a reduction in the spatial resolution to 88 mu m (averaged over the full drift range).

  19. Total electron content responses to HILDCAAs and geomagnetic storms over South America

    Science.gov (United States)

    Mara de Siqueira Negreti, Patricia; Rodrigues de Paula, Eurico; Nicoli Candido, Claudia Maria

    2017-12-01

    Total electron content (TEC) is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs) and the longer-lasting ionospheric disturbance dynamo (DD) electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA) at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE) activity) events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013) the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O / N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil) and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from ˜ 25 to 80 % (compared to quiet time) were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to solar wind forcing and

  20. Total electron content responses to HILDCAAs and geomagnetic storms over South America

    Directory of Open Access Journals (Sweden)

    P. M. de Siqueira Negreti

    2017-12-01

    Full Text Available Total electron content (TEC is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs and the longer-lasting ionospheric disturbance dynamo (DD electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE activity events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013 the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O ∕ N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from  ∼  25 to 80 % (compared to quiet time were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to

  1. Electronics for proportional drift tubes

    International Nuclear Information System (INIS)

    Fremont, G.; Friend, B.; Mess, K.H.; Schmidt-Parzefall, W.; Tarle, J.C.; Verweij, H.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Geske, K.; Riege, H.; Schuett, J.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Semenov, Y.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration)

    1980-01-01

    An electronic system for the read-out of a large number of proportional drift tubes (16,000) has been designed. This system measures deposited charge and drift-time of the charge of a particle traversing a proportional drift tube. A second event can be accepted during the read-out of the system. Up to 40 typical events can be collected and buffered before a data transfer to a computer is necessary. (orig.)

  2. Drift-Scale Radionuclide Transport

    International Nuclear Information System (INIS)

    Houseworth, J.

    2004-01-01

    The purpose of this model report is to document the drift scale radionuclide transport model, taking into account the effects of emplacement drifts on flow and transport in the vicinity of the drift, which are not captured in the mountain-scale unsaturated zone (UZ) flow and transport models ''UZ Flow Models and Submodels'' (BSC 2004 [DIRS 169861]), ''Radionuclide Transport Models Under Ambient Conditions'' (BSC 2004 [DIRS 164500]), and ''Particle Tracking Model and Abstraction of Transport Process'' (BSC 2004 [DIRS 170041]). The drift scale radionuclide transport model is intended to be used as an alternative model for comparison with the engineered barrier system (EBS) radionuclide transport model ''EBS Radionuclide Transport Abstraction'' (BSC 2004 [DIRS 169868]). For that purpose, two alternative models have been developed for drift-scale radionuclide transport. One of the alternative models is a dual continuum flow and transport model called the drift shadow model. The effects of variations in the flow field and fracture-matrix interaction in the vicinity of a waste emplacement drift are investigated through sensitivity studies using the drift shadow model (Houseworth et al. 2003 [DIRS 164394]). In this model, the flow is significantly perturbed (reduced) beneath the waste emplacement drifts. However, comparisons of transport in this perturbed flow field with transport in an unperturbed flow field show similar results if the transport is initiated in the rock matrix. This has led to a second alternative model, called the fracture-matrix partitioning model, that focuses on the partitioning of radionuclide transport between the fractures and matrix upon exiting the waste emplacement drift. The fracture-matrix partitioning model computes the partitioning, between fractures and matrix, of diffusive radionuclide transport from the invert (for drifts without seepage) into the rock water. The invert is the structure constructed in a drift to provide the floor of the

  3. Statistical analysis of geomagnetic field variations during solar eclipses

    Science.gov (United States)

    Kim, Jung-Hee; Chang, Heon-Young

    2018-04-01

    We investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories, which are observed while the Moon's umbra or penumbra passed over them during a solar eclipse event. Though it is generally considered that the geomagnetic field can be modulated during solar eclipses, the effect of the solar eclipse on the observed geomagnetic field has proved subtle to be detected. Instead of exploring the geomagnetic field as a case study, we analyze 207 geomagnetic manifestations acquired by 100 geomagnetic observatories during 39 solar eclipses occurring from 1991 to 2016. As a result of examining a pattern of the geomagnetic field variation on average, we confirm that the effect can be seen over an interval of 180 min centered at the time of maximum eclipse on a site of a geomagnetic observatory. That is, demonstrate an increase in the Y component of the geomagnetic field and decreases in the X component and the total strength of the geomagnetic field. We also find that the effect can be overwhelmed, depending more sensitively on the level of daily geomagnetic events than on the level of solar activity and/or the phase of solar cycle. We have demonstrated it by dividing the whole data set into subsets based on parameters of the geomagnetic field, solar activity, and solar eclipses. It is suggested, therefore, that an evidence of the solar eclipse effect can be revealed even at the solar maximum, as long as the day of the solar eclipse is magnetically quiet.

  4. Geometric effects of ICMEs on geomagnetic storms

    Science.gov (United States)

    Cho, KyungSuk; Lee, Jae-Ok

    2017-04-01

    It has been known that the geomagnetic storm is occurred by the interaction between the Interplanetary Coronal Mass Ejection (ICME) and the Earth's magnetosphere; especially, the southward Bz component of ICME is thought as the main trigger. In this study, we investigate the relationship between Dst index and solar wind conditions; which are the southward Bz, electric field (VBz), and time integral of electric field as well as ICME parameters derived from toroidal fitting model in order to find what is main factor to the geomagnetic storm. We also inspect locations of Earth in ICMEs to understand the geometric effects of the Interplanetary Flux Ropes (IFRs) on the geomagnetic storms. Among 59 CDAW ICME lists, we select 30 IFR events that are available by the toroidal fitting model and classify them into two sub-groups: geomagnetic storms associated with the Magnetic Clouds (MCs) and the compression regions ahead of the MCs (sheath). The main results are as follows: (1) The time integral of electric field has a higher correlation coefficient (cc) with Dst index than the other parameters: cc=0.85 for 25 MC events and cc=0.99 for 5 sheath events. (2) The sheath associated intense storms (Dst ≤-100nT) having usually occur at flank regions of ICMEs while the MC associated intense storms occur regardless of the locations of the Earth in ICMEs. The strength of a geomagnetic storm strongly depends on electric field of IFR and durations of the IFR passages through the Earth.

  5. Progress in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Walton, J.; Gatti, E.

    1985-01-01

    Progress in testing semiconductor drift detectors is reported. Generally better position and energy resolutions were obtained than resolutions published previously. The improvement is mostly due to new electronics better matched to different detectors. It is shown that semiconductor drift detectors are becoming versatile and reliable detectors for position and energy measurements

  6. CTF Void Drift Validation Study

    Energy Technology Data Exchange (ETDEWEB)

    Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gosdin, Chris [Pennsylvania State Univ., University Park, PA (United States); Avramova, Maria N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gergar, Marcus [Pennsylvania State Univ., University Park, PA (United States)

    2015-10-26

    This milestone report is a summary of work performed in support of expansion of the validation and verification (V&V) matrix for the thermal-hydraulic subchannel code, CTF. The focus of this study is on validating the void drift modeling capabilities of CTF and verifying the supporting models that impact the void drift phenomenon. CTF uses a simple turbulent-diffusion approximation to model lateral cross-flow due to turbulent mixing and void drift. The void drift component of the model is based on the Lahey and Moody model. The models are a function of two-phase mass, momentum, and energy distribution in the system; therefore, it is necessary to correctly model the ow distribution in rod bundle geometry as a first step to correctly calculating the void distribution due to void drift.

  7. Geomagnetosystem: charged particle trajectories in the geomagnetic tail

    International Nuclear Information System (INIS)

    Propp, K.E.

    1983-01-01

    The interaction between the solar wind and the magnetic field of the earth results in the formation of a long tail-like structure extending antisolarward. Of central importance in the explanations of the causes and processes involved in the earth's aurorae is the study of the manner in which the magnetotail is formed and maintained. A realistic model of the steady state magnetic field structure is formulated. The magnetic field model is comprised of the geomagnetic dipole field, the field due to the forward magnetopause currents, and the field due to the magnetotail current system. The values and derivatives of the model magnetic field are made available for any position within the geomagnetosystem as the output from specially designed computer subprograms. By numerically integrating both the exact and the guidingcenter approximation equations of motion the motions of protons with energies from 2 eV to 20 keV were studied. All possible pitch and phase angles were used along with the energies to determine a complete range of starting velocities at the center of the magnetotail 40 earth radii distant from the earth. Considerable pitch angle scattering during traversals of the equatorial plane was observed. Nevertheless, the following results were obtained: 1) the phase averaged exact motion results agree well with the phase independent guidingcenter approximation, 2) the dawn to dusk drift velocity in the equatorial region of the tail is nearly independent of pitch angle, 3) the drift velocity which is due to both field line curvature and field gradient is proportional to the proton energy and is approximately as given adiabatic approximations for energies up to 20 keV

  8. Coronal mass ejections and large geomagnetic storms

    International Nuclear Information System (INIS)

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

    1990-01-01

    Previous work indicates that coronal mass ejection (CME) events in the solar wind at 1 AU can be identified by the presence of a flux of counterstreaming solar wind halo electrons (above about 80 eV). Using this technique to identify CMEs in 1 AU plasma data, the authors find that most large geomagnetic storms during the interval surrounding the last solar maximum (Aug. 1978-Oct. 1982) were associated with Earth-passage of interplanetary disturbances in which the Earth encountered both a shock and the CME driving the shock. However, only about one CME in six encountered by Earth was effective in causing a large geomagnetic storm. Slow CMEs which did not interact strongly with the ambient solar wind ahead were particularly ineffective in a geomagnetic sense

  9. Recent Activities Of The World Data Centre For Geomagnetism (Edinburgh)

    OpenAIRE

    Reay, Sarah; Humphries, Tom; Macmillan, Susan; Flower, Simon; Stevenson, Peter; Clarke, Ellen

    2015-01-01

    For almost 50 years the World Data Centre for Geomagnetism (Edinburgh) has been a custodian of geomagnetic data. In particular, over recent years the scope of the data holdings has been increased, quality control measures introduced and better interfaces to make the data more accessible to users are being developed. The WDC hold geomagnetic time-series data from around 280 observatories worldwide at a number of time resolutions along with various magnetic survey, model, and geomagnetic ac...

  10. Subauroral Polarization Streams (SAPS) Duration as Determined From Van Allen Probe Successive Electric Drift Measurements

    Science.gov (United States)

    Lejosne, Solène; Mozer, F. S.

    2017-09-01

    We examine a characteristic feature of the magnetosphere-ionosphere coupling, namely, the persistent and latitudinally narrow bands of rapid westward ion drifts called the subauroral polarization streams (SAPS). Despite countless works on SAPS, information relative to their durations is lacking. Here we report on the first statistical analysis of more than 200 near-equatorial SAPS observations based on more than 2 years of Van Allen Probe electric drift measurements. First, we present results relative to SAPS radial locations and amplitudes. Then, we introduce two different ways to estimate SAPS durations. In both cases, SAPS activity is estimated to last for about 9 h on average. However, our estimates for SAPS duration are limited either by the relatively long orbital periods of the spacecraft or by the relatively small number of observations involved. Fifty percent of the events fit within the time interval [0;18] hours.

  11. Holocene earthquakes of magnitude 7 during westward escape of the Olympic Mountains, Washington

    Science.gov (United States)

    Nelson, Alan R.; Personius, Stephen; Wells, Ray; Schermer, Elizabeth R.; Bradley, Lee-Ann; Buck, Jason; Reitman, Nadine G.

    2017-01-01

    Mountains by north‐directed, margin‐parallel shortening and westward escape of the mountains.

  12. Improvements in geomagnetic observatory data quality

    DEFF Research Database (Denmark)

    Reda, Jan; Fouassier, Danielle; Isac, Anca

    2011-01-01

    between observatories and the establishment of observatory networks has harmonized standards and practices across the world; improving the quality of the data product available to the user. Nonetheless, operating a highquality geomagnetic observatory is non-trivial. This article gives a record...... of the current state of observatory instrumentation and methods, citing some of the general problems in the complex operation of geomagnetic observatories. It further gives an overview of recent improvements of observatory data quality based on presentation during 11th IAGA Assembly at Sopron and INTERMAGNET...

  13. A simple statistical model for geomagnetic reversals

    Science.gov (United States)

    Constable, Catherine

    1990-01-01

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

  14. Geomagnetic Storm Impact On GPS Code Positioning

    Science.gov (United States)

    Uray, Fırat; Varlık, Abdullah; Kalaycı, İbrahim; Öǧütcü, Sermet

    2017-04-01

    This paper deals with the geomagnetic storm impact on GPS code processing with using GIPSY/OASIS research software. 12 IGS stations in mid-latitude were chosen to conduct the experiment. These IGS stations were classified as non-cross correlation receiver reporting P1 and P2 (NONCC-P1P2), non-cross correlation receiver reporting C1 and P2 (NONCC-C1P2) and cross-correlation (CC-C1P2) receiver. In order to keep the code processing consistency between the classified receivers, only P2 code observations from the GPS satellites were processed. Four extreme geomagnetic storms October 2003, day of the year (DOY), 29, 30 Halloween Storm, November 2003, DOY 20, November 2004, DOY 08 and four geomagnetic quiet days in 2005 (DOY 92, 98, 99, 100) were chosen for this study. 24-hour rinex data of the IGS stations were processed epoch-by-epoch basis. In this way, receiver clock and Earth Centered Earth Fixed (ECEF) Cartesian Coordinates were solved for a per-epoch basis for each day. IGS combined broadcast ephemeris file (brdc) were used to partly compensate the ionospheric effect on the P2 code observations. There is no tropospheric model was used for the processing. Jet Propulsion Laboratory Application Technology Satellites (JPL ATS) computed coordinates of the stations were taken as true coordinates. The differences of the computed ECEF coordinates and assumed true coordinates were resolved to topocentric coordinates (north, east, up). Root mean square (RMS) errors for each component were calculated for each day. The results show that two-dimensional and vertical accuracy decreases significantly during the geomagnetic storm days comparing with the geomagnetic quiet days. It is observed that vertical accuracy is much more affected than the horizontal accuracy by geomagnetic storm. Up to 50 meters error in vertical component has been observed in geomagnetic storm day. It is also observed that performance of Klobuchar ionospheric correction parameters during geomagnetic storm

  15. Drifting oscillations in axion monodromy

    Energy Technology Data Exchange (ETDEWEB)

    Flauger, Raphael [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); McAllister, Liam [Department of Physics, Cornell University, Ithaca, NY 14853 (United States); Silverstein, Eva [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305 (United States); Westphal, Alexander, E-mail: flauger@physics.ucsd.edu, E-mail: mcallister@cornell.edu, E-mail: evas@stanford.edu, E-mail: alexander.westphal@desy.de [Theory Group, Deutsches Elektronen-Synchrotron DESY, D-22603 Hamburg (Germany)

    2017-10-01

    We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.

  16. Drifting oscillations in axion monodromy

    International Nuclear Information System (INIS)

    Flauger, Raphael; Westphal, Alexander

    2014-12-01

    We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.

  17. Last three millennia Earth's Magnetic field strength in Mesoamerica and southern United States: Implications in geomagnetism and archaeology

    Science.gov (United States)

    Goguitchaichvili, Avto; Ruiz, Rafael García; Pavón-Carrasco, F. Javier; Contreras, Juan Julio Morales; Arechalde, Ana María Soler; Urrutia-Fucugauchi, Jaime

    2018-06-01

    Earth's Magnetic Field variation strength may provide crucial information to understand the geodynamo mechanism and elucidate the conditions on the physics of the Earth's deep interiors. Aimed to reveal the fine characteristics of the geomagnetic field during the last three millennia in Mesoamerica, we analyzed the available absolute geomagnetic intensities associated to absolute radiometric dating as well some ages provided by historical documents. This analysis is achieved using thermoremanent magnetization carried by volcanic lava flows and burned archaeological artefacts. A total of 106 selected intensities from Mesoamerica and other 100 from the southern part of the United States represent the main core of the dataset to construct the variation curve using both combined bootstrap method and temporal penalized B-spline methods. The obtained intensity paleosecular variation curve for Mesoamerica generally disagrees with the values predicted by the global geomagnetic field models. There is rather firm evidence of eastward drift when compared to similar reference curves in Western Europe, Asia and Pacific Ocean. The recent hypothesis about the relationship between the geomagnetic field strength and paleoclimate is also critically analyzed in the light of this new data compilation.

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

    Directory of Open Access Journals (Sweden)

    N. Longden

    2007-10-01

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

  19. Detection of a westward hotspot offset in the atmosphere of hot gas giant CoRoT-2b

    Science.gov (United States)

    Dang, Lisa; Cowan, Nicolas B.; Schwartz, Joel C.; Rauscher, Emily; Zhang, Michael; Knutson, Heather A.; Line, Michael; Dobbs-Dixon, Ian; Deming, Drake; Sundararajan, Sudarsan; Fortney, Jonathan J.; Zhao, Ming

    2018-03-01

    Short-period planets exhibit day-night temperature contrasts of hundreds to thousands of kelvin. They also exhibit eastward hotspot offsets whereby the hottest region on the planet is east of the substellar point1; this has been widely interpreted as advection of heat due to eastward winds2. We present thermal phase observations of the hot Jupiter CoRoT-2b obtained with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. These measurements show the most robust detection to date of a westward hotspot offset of 23 ± 4°, in contrast with the nine other planets with equivalent measurements3-10. The peculiar infrared flux map of CoRoT-2b may result from westward winds due to non-synchronous rotation11 or magnetic effects12,13, or partial cloud coverage, that obscure the emergent flux from the planet's eastern hemisphere14-17. Non-synchronous rotation and magnetic effects may also explain the planet's anomalously large radius12,18. On the other hand, partial cloud coverage could explain the featureless dayside emission spectrum of the planet19,20. If CoRoT-2b is not tidally locked, then it means that our understanding of star-planet tidal interaction is incomplete. If the westward offset is due to magnetic effects, our result represents an opportunity to study an exoplanet's magnetic field. If it has eastern clouds, then it means that a greater understanding of large-scale circulation on tidally locked planets is required.

  20. Geomagnetic activity and the North Atlantic Oscillation

    Czech Academy of Sciences Publication Activity Database

    Bucha, Václav

    2014-01-01

    Roč. 58, č. 3 (2014), s. 461-472 ISSN 0039-3169 Institutional support: RVO:67985530 Keywords : geomagnetic activity * solar wind * polar vortex intensification * downward winds Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.806, year: 2014

  1. Geomagnetic secular variation at the African observatories

    International Nuclear Information System (INIS)

    Haile, T.

    2002-10-01

    Geomagnetic data from ten observatories in the African continent with time series data length of more than three decades have been analysed. All-day annual mean values of the D, H and Z components were used to study secular variations in the African region. The residuals in D, H and Z components obtained after removing polynomial fits have been examined in relation to the sunspot cycle. The occurrence of the 1969-1970 worldwide geomagnetic impulse in each observatory is studied. It is found that the secular variation in the field can be represented for most of the observatories with polynomials of second or third degree. Departures from these trends are observed over the Southern African region where strong local magnetic anomalies have been observed. The residuals in the geomagnetic field components have been shown to exhibit parallelism with the periods corresponding to double solar cycle for some of the stations. A clear latitudinal distribution in the geomagnetic component that exhibits the 1969-70 jerk is shown. The jerk appears in the plots of the first differences in H for the southern most observatories of Hermanus, Hartebeesthoek, and Tsuemb, while the Z plots show the jerk for near equatorial and equatorial stations of Antananarivo, Luanda Belas, Bangui and Addis Ababa. There is some indication for this jerk in the first difference plots of D for the northern stations of M'Bour and Tamanrasset. The plots of D rather strongly suggest the presence of a jerk around 1980 at most of the stations. (author)

  2. Geomagnetic activity and the global temperature

    Czech Academy of Sciences Publication Activity Database

    Bucha, Václav

    2009-01-01

    Roč. 53, č. 4 (2009), s. 571-573 ISSN 0039-3169 Institutional research plan: CEZ:AV0Z30120515 Keywords : global warming * Southern Oscillation * geomagnetic storms Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.000, year: 2009

  3. Some aspects of geomagnetically conjugate phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Rycroft, M.J.

    1987-12-01

    Both charged particles and waves convey information about the thermosphere, ionosphere and magnetosphere from the Northern to the Southern Hemisphere and vice versa, along geomagnetic flux tubes.The interhemispheric travel time of electrons or ions, being dependent upon L-value , pitch angle and energy (which may lie between less than or equal to 1 eV and greater than or equal to 1 MeV) may be many hours, ranging down to less than or equal to 1 s. However, the one-hop propagation time for magnetohydrodynamic or whistler mode waves generally lies between 10/sup 2/s and 1 s. Such times, therefore, give the time scales of transient phenomena that are geomagnetically conjugate and of changes in steady-state plasma processes occurring in geomagnetically conjugate regions. Contrasting examples are presented of conjugate physical phenomena, obtained using satellite, rocket, aircraft and ground-based observations; the latter capitalise upon the rather rare disposition of land - rather than ocean - at each end of a geophysically interesting flux tube. Particular attention is paid to the interactions between whistler mode waves and energetic electrons. Geomagnetic, radio, optical and plasma observations, taken together with model computations, provide a wealth of knowledge on conjugate phenomena and their dependence on conditions in the solar wind, substorms, L-value, etc... Finally, some suggestions are made for future lines of research.

  4. Drift chamber data readout system

    International Nuclear Information System (INIS)

    Basiladze, S.G.; Lokhonyai, L.

    1980-01-01

    An electronic system for processing drift chamber signals is described. The system consists of 4-channel fast amplifier-discriminators of low threshold, 16-channel time-expanders transforming 0.5 μs time intervals to 10 μs and a 9-bit time-to-digital converter (TDC) recording up to 16 expanded time intervals. If the average track multiplicity is small, TDC is capable to process signals from 4 time-expanders (i.e., 64 drift gaps). In order to record multiple tracks per drift gap discriminator outputs can be connected to a number of time-expander channels. The fast clear input enables the system to be cleared within 0.5 μs. Efficient readout from TDC is facilated by reading only those channels which contain non-zero data (9 bits - drift time; 6 bits - wire number)

  5. Drift tubes of Linac 2

    CERN Multimedia

    Photographic Service

    1977-01-01

    Being redied for installation, those at the right are for tank 1, those on the left for tank 2. Contrary to Linac 1, which had drift-tubes supported on stems, here the tubes are suspended, for better mechanical stability.

  6. What do we mean by accuracy in geomagnetic measurements?

    Science.gov (United States)

    Green, A.W.

    1990-01-01

    High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

  7. On nonlinear periodic drift waves

    International Nuclear Information System (INIS)

    Kauschke, U.; Schlueter, H.

    1990-09-01

    Nonlinear periodic drift waves are investigated on the basis of a simple perturbation scheme for both the amplitude and inverse frequency. The coefficients for the generation of the forced harmonics are derived, a nonlinear dispersion relation is suggested and a criterion for the onset of the modulational instability is obtained. The results are compared with the ones obtained with the help of a standard KBM-treatment. Moreover cnoidal drift waves are suggested and compared to an experimental observation. (orig.)

  8. The OPAL vertex drift chamber

    International Nuclear Information System (INIS)

    Carter, J.R.; Elcombe, P.A.; Hill, J.C.; Roach, C.M.; Armitage, J.C.; Carnegie, R.K.; Estabrooks, P.; Hemingway, R.; Karlen, D.; McPherson, A.; Pinfold, J.; Roney, J.M.; Routenburg, P.; Waterhouse, J.; Hargrove, C.K.; Klem, D.; Oakham, F.G.; Carter, A.A.; Jones, R.W.L.; Lasota, M.M.B.; Lloyd, S.L.; Pritchard, T.W.; Wyatt, T.R.

    1990-01-01

    A high precision vertex drift chamber has been installed in the OPAL experiment at LEP. The design of the chamber and the associated readout electronics is described. The performance of the system has been studied using cosmic ray muons and the results of these studies are presented. A space resolution of 50 μm in the drift direction is obtained using the OPAL central detector gas mixture at 4 bar. (orig.)

  9. Geomagnetic field evolution during the Laschamp excursion

    Science.gov (United States)

    Leonhardt, Roman; Fabian, Karl; Winklhofer, Michael; Ferk, Annika; Laj, Carlo; Kissel, Catherine

    2009-02-01

    Since the last geomagnetic reversal, 780,000 years ago, the Earth's magnetic field repeatedly dropped dramatically in intensity. This has often been associated with large variations in local field direction, but without a persistent global polarity flip. The structure and dynamics of geomagnetic excursions, and especially the difference between excursions and polarity reversals, have remained elusive so far. For the best documented excursion, the Laschamp event at 41,000 years BP, we have reconstructed the evolution of the global field morphology by using a Bayesian inversion of several high-resolution palaeomagnetic records. We have obtained an excursion scenario in which inverse magnetic flux patches at the core-mantle boundary emerge near the equator and then move poleward. Contrary to the situation during the last reversal (Leonhardt, R., Fabian, K., 2007. Paleomagnetic reconstruction of the global geomagnetic field evolution during the Matuyama/Brunhes transition: Iterative Bayesian inversion and independent verification. Earth Planet. Sci. Lett. 253, 172-195), these flux patches do not cross the hydrodynamic boundary of the inner-core tangent cylinder. While the last geomagnetic reversal began with a substantial increase in the strength of the non-dipolar field components, prior to the Laschamp excursion, both dipolar and non-dipolar field decay at the same rate. This result suggests that the nature of an upcoming geomagnetic field instability can be predicted several hundred years in advance. Even though during the Laschamp excursion the dipolar field at the Earth's surface was dominant, the reconstructed dynamic non-dipolar components lead to considerable deviations among predicted records at different locations. The inverse model also explains why at some locations no directional change during the Laschamp excursion is observed.

  10. Generalized drift-flux correlation

    International Nuclear Information System (INIS)

    Takeuchi, K.; Young, M.Y.; Hochreiter, L.E.

    1991-01-01

    A one-dimensional drift-flux model with five conservation equations is frequently employed in major computer codes, such as TRAC-PD2, and in simulator codes. In this method, the relative velocity between liquid and vapor phases, or slip ratio, is given by correlations, rather than by direct solution of the phasic momentum equations, as in the case of the two-fluid model used in TRAC-PF1. The correlations for churn-turbulent bubbly flow and slug flow regimes were given in terms of drift velocities by Zuber and Findlay. For the annular flow regime, the drift velocity correlations were developed by Ishii et al., using interphasic force balances. Another approach is to define the drift velocity so that flooding and liquid hold-up conditions are properly simulated, as reported here. The generalized correlation is used to reanalyze the MB-2 test data for two-phase flow in a large-diameter pipe. The results are applied to the generalized drift flux velocity, whose relationship to the other correlations is discussed. Finally, the generalized drift flux correlation is implemented in TRAC-PD2. Flow reversal from countercurrent to cocurrent flow is computed in small-diameter U-shaped tubes and is compared with the flooding curve

  11. The Drifting Star

    Science.gov (United States)

    2008-04-01

    By studying in great detail the 'ringing' of a planet-harbouring star, a team of astronomers using ESO's 3.6-m telescope have shown that it must have drifted away from the metal-rich Hyades cluster. This discovery has implications for theories of star and planet formation, and for the dynamics of our Milky Way. ESO PR Photo 09a/08 ESO PR Photo 09a/08 Iota Horologii The yellow-orange star Iota Horologii, located 56 light-years away towards the southern Horologium ("The Clock") constellation, belongs to the so-called "Hyades stream", a large number of stars that move in the same direction. Previously, astronomers using an ESO telescope had shown that the star harbours a planet, more than 2 times as large as Jupiter and orbiting in 320 days (ESO 12/99). But until now, all studies were unable to pinpoint the exact characteristics of the star, and hence to understand its origin. A team of astronomers, led by Sylvie Vauclair from the University of Toulouse, France, therefore decided to use the technique of 'asteroseismology' to unlock the star's secrets. "In the same way as geologists monitor how seismic waves generated by earthquakes propagate through the Earth and learn about the inner structure of our planet, it is possible to study sound waves running through a star, which forms a sort of large, spherical bell," says Vauclair. The 'ringing' from this giant musical instrument provides astronomers with plenty of information about the physical conditions in the star's interior. And to 'listen to the music', the astronomers used one of the best instruments available. The observations were conducted in November 2006 during 8 consecutive nights with the state-of-the-art HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla. Up to 25 'notes' could be identified in the unique dataset, most of them corresponding to waves having a period of about 6.5 minutes. These observations allowed the astronomers to obtain a very precise portrait of Iota Horologii: its

  12. Classification and quantification of solar wind driver gases leading to intense geomagnetic storms

    Science.gov (United States)

    Adekoya, B. J.; Chukwuma, V. U.

    2018-01-01

    Classification and quantification of the interplanetary structures causing intense geomagnetic storms (Dst ≤ -100 nT) that occurred during 1997-2016 are studied. The subject of this consists of solar wind parameters of seventy-three intense storms that are associated with the southward interplanetary magnetic field. About 30.14% of the storms were driven by a combination of the sheath and ejecta (S + E), magnetic clouds (MC) and sheath field (S) are 26% each, 10.96% by combined sheath and MCs (S + C), while 5.48% of the storms were driven by ejecta (E) alone. Therefore, we want to aver that for storms driven by: (1) S + E. The Bz is high (≥10 nT), high density (ρ) (>10 N/cm3), high plasma beta (β) (>0.8), and unspecified (i.e. high or low) structure of the plasma temperature (T) and the flow speed (V); (2) MC. The Bz is ≥10 nT, low temperature (T ≤ 400,000 K), low ρ (≤10 N/cm3), high V (≥450 km), and low β (≤0.8); (3) The structures of S + C are similar to that of MC except that the V is low (V ≤ 450 km); (4) S. The Bz is high, low T, high ρ, unspecified V, and low β; and (5) E. Is when the structures are directly opposite of the one driven by MCs except for high V. Although, westward ring current indicates intense storms, but the large intensity of geomagnetic storms is determined by the intense nature of the electric field strength and the Bz. Therefore, great storms (i.e. Dst ≤ -200 nT) are manifestation of high electric field strength (≥13 mV/m).

  13. Characteristic parameters of drift chambers calculation

    International Nuclear Information System (INIS)

    Duran, I.; Martinez-Laso, L.

    1989-01-01

    We present here the methods we used to analyse the characteristic parameters of drift chambers. The algorithms to calculate the electric potential in any point for any drift chamber geometry are presented. We include the description of the programs used to calculate the electric field, the drift paths, the drift velocity and the drift time. The results and the errors are discussed. (Author) 7 refs

  14. Plasma drifts associated with a system of sun-aligned arcs in the polar cap

    International Nuclear Information System (INIS)

    Mende, S.B.; Doolittle, J.H.; Robinson, R.M.; Vondrak, R.R.; Rich, F.J.

    1988-01-01

    A series of four sun-aligned arcs passed over Sondre Stromfjord, Greenland, on the night of the 17th and 18th of February, 1985. Observations of these arcs were made using the Sondrestrom incoherent scatter radar and an intensified all-sky imaging TV system that was operated at the radar site. The first of the four arcs crossed the Sondre Stromfjord meridian just before local midnight moving westward, and the other three arcs followed at approximately half-hour intervals. When we account for the earth's rotation, the arc drift in an inertial frame was eastward, or dusk to dawn. The half-hour interval between meridian crossings of the arcs implies that the mean spacing between the arcs was 180 km. A Defense Meteorological Satellite Program (DMSP) F6 satellite pass at 0110 UT revealed the presence of highly structured electron and ion precipitation throughout the polar cap. The DMSP visible imager detected a single, sun-aligned arc associated with the largest peak in precipitating electron flux. This arc was also observed at Thule, Greenland, with an intensified film camera. These observations suggest that at least one of the arcs that were observed at Sondre Stromfjord extended across a large part of the polar cap. The radar at Sondre Stromfjord measured electron density and ion drift velocities associated with the four arcs. The radar drift measurements were superimposed on the all-sky video images to determine the location of the measurements relative to the arcs. Plasma drifts outside the arcs were found to be both sunward and antisunward, while within the arcs the drifts were predominantly antisunward. The variability of the drifts in the direction parallel to the arcs indicates that the electric fields were highly structured even though the configuration and motion of the arcs were well behaved

  15. In-Drift Microbial Communities

    Energy Technology Data Exchange (ETDEWEB)

    D. Jolley

    2000-11-09

    As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses.

  16. In-Drift Microbial Communities

    International Nuclear Information System (INIS)

    Jolley, D.

    2000-01-01

    As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses

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

    International Nuclear Information System (INIS)

    Chu, W.; Univ. of Chinese Academy of Sciences, Beijing; Qin, G.

    2016-01-01

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

  18. Mathematical Properties Relevant to Geomagnetic Field Modeling

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils

    2010-01-01

    be directly measured. In this chapter, the mathematical foundation of global (as opposed to regional) geomagnetic field modeling is reviewed, and the spatial modeling of the field in spherical coordinates is focussed. Time can be dealt with as an independent variable and is not explicitly considered......Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations.The set of numerical coefficients defining this linear combination is then what one refers.......The relevant elementary mathematical functions are introduced, their properties are reviewed, and how they can be used to describe the magnetic field in a source-free (such as the Earth’s neutral atmosphere) or source-dense (such as the ionosphere) environment is explained. Completeness and uniqueness...

  19. Mathematical Properties Relevant to Geomagnetic Field Modeling

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils

    2014-01-01

    be directly measured. In this chapter, the mathematical foundation of global (as opposed to regional) geomagnetic field modeling is reviewed, and the spatial modeling of the field in spherical coordinates is focused. Time can be dealt with as an independent variable and is not explicitly considered......Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations. The set of numerical coefficients defining this linear combination is then what one refers....... The relevant elementary mathematical functions are introduced, their properties are reviewed, and how they can be used to describe the magnetic field in a source-free (such as the Earth’s neutral atmosphere) or source-dense (such as the ionosphere) environment is explained. Completeness and uniqueness...

  20. Solar wind velocity and geomagnetic moment variations

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Rozanova, T.S.

    1982-01-01

    The mean year values of the solar wind velocity have been calculated from the mean-year values of a geomagnetic activity index am according to the Svalgard equation of regression for the pe-- riod from 1930 to 1960. For the same years the values of the geomagnetic moment M and separately of its ''inner'' (causes of which'' are inside the Earth) and ''external'' (causes of which are outside the Earth) parts have been calculated from the mean year data of 12 magnetic observatories. The proof of the presence of the 11-year variation in the moment M has been obtained. It is concluded that the 11-year variations in M result from the variations of the solar wind velocity

  1. Geomagnetic oriented electromagnetic radiation in the ionosphere

    International Nuclear Information System (INIS)

    Benton, C.U.; Fowles, H.M.; Goen, P.K.

    1976-08-01

    Strong bursts of electromagnetic radiation were observed in the ionosphere during the Waso rocket Electromagnetic Pulse (EMP) experiment. The pulses have a frequency content from below 20 MHz to above 70 MHz. They vary in duration between 5 μs and 2 ms and in peak-amplitudes of 2 mV/m to greater than 200 mV/m. These pulses show a high degree of geomagnetic correlation and are of unknown origin

  2. Geomagnetic fluctuations during a polarity transition

    Science.gov (United States)

    Audunsson, Haraldur; Levi, Shaul

    1997-01-01

    The extensive Roza Member of the Columbia River Basalt Group (Washington State) has intermediate paleomagnetic directions, bracketed by underlying normal and overlying reverse polarity flows. A consistent paleomagnetic direction was measured at 11 widely distributed outcrops; the average direction has a declination of 189° and an inclination of -5°, with greater variation in the inclination [Rietman, 1966]. In this study the Roza Member was sampled in two Pasco Basin drillcores, where it is a single cooling unit and its thickness exceeds 50 m. Excellent core recovery allowed uniform and dense sampling of the drillcores. During its protracted cooling, the Roza flow in the drillcores recorded part of a 15.5 Ma geomagnetic polarity transition. The inclination has symmetric, quasicyclic intraflow variation, while the declination is nearly constant, consistent with the results from the outcrops. Thermal models of the cooling flow provide the timing for remanence acquisition. The inclination is inferred to have progressed from 0° to -15° and back to -3°over a period of 15 to 60 years, at rates of 1.6° to 0.5°/yr. Because the geomagnetic intensity was probably weak during the transition, these apparently high rates of change are not significantly different from present-day secular variation. These results agree with the hypothesis that normal secular variation persists through geomagnetic transitions. The Iow-amplitude quasicyclical fluctuations of the field over tens of years, recorded by Roza, suggest that the geomagnetic field reverses in discrete steps, and that more than 15-60 years were required to complete this reversal.

  3. Uncertainty Quantification in Geomagnetic Field Modeling

    Science.gov (United States)

    Chulliat, A.; Nair, M. C.; Alken, P.; Meyer, B.; Saltus, R.; Woods, A.

    2017-12-01

    Geomagnetic field models are mathematical descriptions of the various sources of the Earth's magnetic field, and are generally obtained by solving an inverse problem. They are widely used in research to separate and characterize field sources, but also in many practical applications such as aircraft and ship navigation, smartphone orientation, satellite attitude control, and directional drilling. In recent years, more sophisticated models have been developed, thanks to the continuous availability of high quality satellite data and to progress in modeling techniques. Uncertainty quantification has become an integral part of model development, both to assess the progress made and to address specific users' needs. Here we report on recent advances made by our group in quantifying the uncertainty of geomagnetic field models. We first focus on NOAA's World Magnetic Model (WMM) and the International Geomagnetic Reference Field (IGRF), two reference models of the main (core) magnetic field produced every five years. We describe the methods used in quantifying the model commission error as well as the omission error attributed to various un-modeled sources such as magnetized rocks in the crust and electric current systems in the atmosphere and near-Earth environment. A simple error model was derived from this analysis, to facilitate usage in practical applications. We next report on improvements brought by combining a main field model with a high resolution crustal field model and a time-varying, real-time external field model, like in NOAA's High Definition Geomagnetic Model (HDGM). The obtained uncertainties are used by the directional drilling industry to mitigate health, safety and environment risks.

  4. Modeling the ocean effect of geomagnetic storms

    DEFF Research Database (Denmark)

    Olsen, Nils; Kuvshinov, A.

    2004-01-01

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

  5. Elliptical magnetic clouds and geomagnetic storms

    Czech Academy of Sciences Publication Activity Database

    Antoniadou, I.; Geranios, A.; Vandas, Marek; Panagopoulou, M.; Zacharopoulou, O.; Malandraki, O.

    2008-01-01

    Roč. 56, 3-4 (2008), s. 492-500 ISSN 0032-0633 R&D Projects: GA AV ČR 1QS300120506; GA ČR GA205/06/0875 Institutional research plan: CEZ:AV0Z10030501 Keywords : magnetic clouds * geomagnetic storms * solar wind Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.506, year: 2008

  6. Drift tubes of Linac 2

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    With the advent of the 800 MeV PS Booster in 1972, the original injector of the PS, a 50 MeV Alvarez-type proton linac, had reached its limits, in terms of intensity and stability. In 1973 one therefore decided to build a new linac (Linac 2), also with a drift-tube Alvarez structure and an energy of 50 MeV. It had a new Cockcroft-Walton preinjector with 750 keV, instead of the previous one with 500 keV. Linac 2 was put into service in 1980. The old Linac 1 was then used for the study of, and later operation with, various types of ions. This picture shows Linac 2 drift-tubes, suspended on stems coming from the top, in contrast to Linac 1, where the drift-tubes stood on stems coming from the bottom.

  7. Domino model for geomagnetic field reversals.

    Science.gov (United States)

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

    2013-01-01

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

  8. AI techniques in geomagnetic storm forecasting

    Science.gov (United States)

    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.

  9. Geomagnetic storm under laboratory conditions: randomized experiment

    Science.gov (United States)

    Gurfinkel, Yu I.; Vasin, A. L.; Pishchalnikov, R. Yu; Sarimov, R. M.; Sasonko, M. L.; Matveeva, T. A.

    2017-10-01

    The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

  10. Geomagnetic storm under laboratory conditions: randomized experiment.

    Science.gov (United States)

    Gurfinkel, Yu I; Vasin, A L; Pishchalnikov, R Yu; Sarimov, R M; Sasonko, M L; Matveeva, T A

    2018-04-01

    The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

  11. Predicting public sector accountability : From agency drift to forum drift

    NARCIS (Netherlands)

    Schillemans, Thomas|info:eu-repo/dai/nl/229913881; Busuioc, Madalina

    2015-01-01

    Principal-agent theory has been the dominant theory at the heart of public sector accountability research. The notion of the potentially drifting agent-such as independent public agencies, opaque transnational institutions, or recalcitrant street-level bureaucrats-has been the guiding paradigm in

  12. Latitudinally propagating on-off switching aurorae and associated geomagnetic pulsations

    International Nuclear Information System (INIS)

    Oguti, T.; Kokubun, S.; Hayashi, K.; Tsuruda, K.; Machida, S.; Kitamura, T.; Saka, O.; Watanabe, T.

    1981-01-01

    Poleward propagating on-off switching aurorae and equatorward propagating aurorae, otherwise similar, were observed simultaneously at Rabbit Lake and La Ronge, respectively, for about 40 min before dawn of Feb 20, 1980. Rabbit Lake is a high auroral latitude site at the northern end of the Saskatchewan chain of stations for the Pulsating Aurora Campaign, whereas La Ronge, due south of Rabbit, is almost at the southern edge of the auroral zone. The repetition periods of the on-off switching aurorae are about 6 to 13 s. The poleward propagating aurorae had well defined fronts of light which extended a few hundred kilometres or more in the east-west direction. The light fronts of the equatorward propagating aurorae, though comparable in extent, were less well defined: they were thicker and fuzzier. The poleward propagating aurorae moved with a speed of approximately 10 km/s whereas the equatorward ones did so with a slightly greater velocity. Geomagnetic field fluctuations were concurrent with the aurorae at both sites. At Rabbit Lake, northward (southward) field changes were associated with upward (downward) changes, whereas the trend is reversed at La Ronge, viz., northward (southward) changes with downward (upward) changes. These trends are consistent with a model of a periodic occurrence of two line currents, westward and eastward, the former moving poleward north of Rabbit Lake and the latter approaching La Ronge from the north

  13. An impending geomagnetic transition? Hints from the past

    OpenAIRE

    Laj, Carlo; Kissel, Catherine

    2015-01-01

    The rapid decrease of the geomagnetic field intensity in the last centuries has led to speculations that an attempt to a reversal or an excursion might be under way. Here we investigate this hypothesis by examining past records of geomagnetic field intensity obtained from sedimentary cores and from the study of cosmogenic nuclides. The selected records describe geomagnetic changes with an unprecedented temporal resolution between 20 and 75 kyr B.P. We find that some aspects of the present-day...

  14. Collisional drift fluid equations and implications for drift waves

    International Nuclear Information System (INIS)

    Pfirsch, Dieter; Correa-Restrepo, Dario

    1996-01-01

    The usual theoretical description of drift-wave turbulence (considered to be one possible cause of anomalous transport in a plasma), e.g. the Hasegawa-Wakatani theory, makes use of various approximations, the effects of which are extremely difficult to assess. This concerns in particular the conservation laws for energy and momentum. The latter law is important in relation to charge separation and the resulting electric fields, which are possibly related to the L-H transition. Energy conservation is crucial to the stability behaviour, it will be discussed by means of an example. New collisional multi-species drift-fluid equations were derived by a new method which yields, in a transparent way, conservation of energy and total angular momentum and the law for energy dissipation. Both electrostatic and electromagnetic field variations are considered. The only restriction involved is the validity of the drift approximation; in particular, there are no assumptions restricting the geometry of the system. The method is based primarily on a Lagrangian for dissipationless fluids in the drift approximation with isotropic pressures. The dissipative terms are introduced by adding corresponding terms to the ideal equations of motion and of the pressures. The equations of motion, of course, no longer result from a Lagrangian via Hamilton's principle. However, their relation to the ideal equations also implies a relation to the ideal Lagrangian, which can be used to advantage. Instead of introducing heat conduction one can also assume isothermal behaviour, e.g. T v (x) = constant. Assumptions of this kind are often made in the literature. The new method of introducing dissipation is not restricted to the present kind of theory; it can equally well be applied to theories such as multi-fluid theories without using the drift approximation of the present paper. (author)

  15. Solar Drift-Pair Bursts

    Science.gov (United States)

    Stanislavsky, A.; Volvach, Ya.; Konovalenko, A.; Koval, A.

    2017-08-01

    In this paper a new sight on the study of solar bursts historically called drift pairs (DPs) is presented. Having a simple morphology on dynamic spectra of radio records (two short components separated in time, and often they are very similar) and discovered at the dawn of radio astronomy, their features remain unexplained totally up to now. Generally, the DPs are observed during the solar storms of type III bursts, but not every storm of type III bursts is linked with DPs. Detected by ground-based instruments at decameter and meter wavelengths, the DP bursts are limited in frequency bandwidth. They can drift from high frequencies to low ones and vice versa. Their frequency drift rate may be both lower and higher than typical rates of type III bursts at the same frequency range. The development of low-frequency radio telescopes and data processing provide additional possibilities in the research. In this context the fresh analysis of DPs, made from recent observations in the summer campaign of 2015, are just considered. Their study was implemented by updated tools of the UTR-2 radio telescope at 9-33 MHz. During 10-12 July of 2015, DPs forming the longest patterns on dynamic spectra are about 7% of the total number of recorded DPs. Their marvelous resemblance in frequency drift rates with the solar S-bursts is discussed.

  16. Job satisfaction and preference drift.

    NARCIS (Netherlands)

    Maassen van den Brink, H.; Groot, W.J.N.

    1999-01-01

    Most empirical studies do not find that higher wages lead to more job satisfaction. In this paper we argue that the insignificant effect of wages on job satisfaction is due to preference drift. We adapt the standard ordered response model to allow for preference shifts. The empirical results support

  17. The Egyptian geomagnetic reference field to the Epoch, 2010.0

    Directory of Open Access Journals (Sweden)

    H.A. Deebes

    2017-06-01

    The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF 2010 is indicated.

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

    Science.gov (United States)

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

    2012-12-01

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

  19. Electromagnetic core-mantle coupling associated with changes in the geomagnetic dipole field

    International Nuclear Information System (INIS)

    Watanabe, Hidehumi; Yukutake, Takesi.

    1975-01-01

    On a shelluar earth model electromagnetic coupling between the mantle and the core is investigated when the geomagnetic dipole field changes its intensity. Besides electromagnetic interaction between the dipole change and the relative slip of the mantle to the core, coupling of the dipole change with shear motions within the core is considered. If, in the core, the dipole change is limited within a surface layer shallower than a few hundred kilometers, the electromagnetic interaction gives the same order of magnitudes and phases of mantle oscillation as suggested from observation for three different periods, 8000, 400 and 65 years, provided that the electrical conductivity of the bottom part of the mantle is 10 -9 to 10 -8 emu. It is shown that mean motion of the surface shells of the core thus calculated is compatible with the observed variations in the drift velocity of the geomagnetic secular change. Except for surface shells, those in the deep interior is confirmed to oscillate almost with the same angular velocity, like a rigid rotation, for all the periods. (auth.)

  20. Distinct Pattern of Solar Modulation of Galactic Cosmic Rays above a High Geomagnetic Cutoff Rigidity

    Science.gov (United States)

    Mangeard, Pierre-Simon; Clem, John; Evenson, Paul; Pyle, Roger; Mitthumsiri, Warit; Ruffolo, David; Sáiz, Alejandro; Nutaro, Tanin

    2018-05-01

    Solar modulation refers to Galactic cosmic-ray variations with the ∼11 yr sunspot cycle and ∼22 yr solar magnetic cycle and is relevant to the space radiation environment and effects on Earth’s atmosphere. Its complicated dependence on solar and heliospheric conditions is only roughly understood and has been empirically modeled in terms of a single modulation parameter. Most analyses of solar modulation use neutron monitor (NM) data from locations with relatively low geomagnetic cutoff rigidity, i.e., the threshold for cosmic rays to penetrate Earth’s magnetic field. The Princess Sirindhorn Neutron Monitor at Doi Inthanon, Thailand, has the world’s highest cutoff rigidity (≈17 GV) where observations span a complete solar modulation cycle (since late 2007). The pattern of solar modulation at Doi Inthanon during 2011–2014 was qualitatively very different from that at a low geomagnetic cutoff and is not well described by the same modulation parameter. At other times, NM count rates from Doi Inthanon and McMurdo, Antarctica (cutoff ∼1 GV), were linearly correlated and confirm the observation from latitude surveys in the previous solar cycle that the slope of the correlation changes with solar magnetic polarity. Low solar magnetic tilt angles (magnetic field, which is consistent with an increase in diffusion at high rigidity short-circuiting the effects of drifts and the heliospheric current sheet.

  1. Energetic particle drift motions in the outer dayside magnetosphere

    International Nuclear Information System (INIS)

    Buck, R.M.

    1987-12-01

    Models of the geomagnetic field predict that within a distance of approximately one earth radius inside the dayside magnetopause, magnetic fields produced by the Chapman-Ferraro magnetopause currents create high-latitude minimum-B ''pockets'' in the geomagnetic field. Drift-shell branching caused by the minimum-B pockets is analyzed and interpreted in terms of an adiabatic shell branching and rejoining process. We examine the shell-branching process for a static field in detail, using the Choe-Beard 1974 magnetospheric magnetic field model. We find that shell branching annd rejoining conserves the particle mirror field B/sub M/, the fieldline integral invariant I, and the directional electron flux j. We determine the spatial extent of the stable trapping regions for the Choe-Beard model. We develop an adiabatic branching map methodology which completely identifies and describes the location of shell-branching points and the adiabatic trajectories of particles on branched shells, for any model field. We employ the map to develop synthetic pitch angle distributions near the dayside magnetopause by adiabatically transforming observed midnight distributions to the dayside. We find that outer dayside lines contain particles moving on branched and unbranched shells, giving rise to distinctive pitch angle distribution features. We find a good correlation between the pitch angles which mark the transition from branched to unbranched shells in the model, and the distinctive features of the OGO-5 distributions. In the morning sector, we observe large flux changes at critical pitch angles which correspond to B-pocket edges in the model. Measurements on inbound passes in the afternoon sector show first the adiabatic particle shadow, then the arrival of fluxes on rejoined shells, then fluxes on unbranced shells - in accord with model predictions. 204 refs., 138 figs., 2 tabs

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

    Science.gov (United States)

    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

  3. Ten cycles of solar and geomagnetic activity

    International Nuclear Information System (INIS)

    Legrand, J.P.

    1981-01-01

    Series of 110 years of sunspot numbers and indices of geomagnetic activity are used with 17 years of solar wind data in order to study through solar cycles both stream and shock event solar activity. According to their patterns on Bartels diagrams of geomagnetic indices, stable wind streams and transient solar activities are separated from each other. Two classes of stable streams are identified: equatorial streams occurring sporadically, for several months, during the main phase of sunspot cycles and both polar streams established, for several years, at each cycle, before sunspot minimum. Polar streams are the first activity of solar cycles. For study of the relationship between transient geomagnetic phenomena and sunspot activity, we raise the importance of the contribution, at high spot number, of severe storms and, at low spot number, of short lived and unstable streams. Solar wind data are used to check and complete the above results. As a conclusion, we suggest a unified scheme of solar activity evolution with a starting point every eleventh year, a total duration of 17 years and an overlapping of 6 years between the first and the last phase of both successive series of phenomena: first, from polar field reversal to sunspot minimum, a phase of polar wind activity of the beginning cycle is superimposed on the weak contribution of shock events of the ending cycle; secondly, an equatorial phase mostly of shock events is superimposed on a variable contribution of short lived and sporadic stable equatorial stream activities; and thirdly a phase of low latitude shock events is superimposed on the polar stream interval of the following cycle. (orig.)

  4. Drift Chambers detectors; Detectores de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I; Martinez laso, L

    1989-07-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs.

  5. Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

    NARCIS (Netherlands)

    Linssen, J.H.

    1991-01-01

    In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its

  6. International Geomagnetic Reference Field: the 12th generation

    DEFF Research Database (Denmark)

    Thébault, Erwan; Finlay, Chris; Beggan, Ciarán D.

    2015-01-01

    The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch ...

  7. Geomagnetic observations on Tristan da Cunha, South Atlantic Ocean

    DEFF Research Database (Denmark)

    Matzka, J.; Olsen, Nils; Maule, C. F.

    2009-01-01

    Few geomagnetic ground observations exist of the Earth's strongest core field anomaly, the South Atlantic Anomaly (SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa and South America at 37 degrees 05' S, 12 degrees 18' W, is therefore of cr...

  8. Computation of geomagnetic elements for Nigeria for the year 2000 ...

    African Journals Online (AJOL)

    The Earth's magnetic field may be considered to be the sum of two parts, the main geomagnetic field which originates from the earth's fluid core, and the anomaly field that has its sources in the earth crust. The analysis of the geomagnetic field residual or anomaly, obtained from the difference between these two sources are ...

  9. Geomagnetic Field Variation during Winter Storm at Localized ...

    Indian Academy of Sciences (India)

    that transports plasma and magnetic flux which create the geomagnetic field variation. Key words. Dst—vertical component of interplanetary magnetic field and geomagnetic field components. 1. Introduction. The magnetic field is one of the important properties of the earth. The main magnetic field originates from ...

  10. ATLAS Muon Drift Tube Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Arai, Y [KEK, High Energy Accelerator Research Organisation, Tsukuba (Japan); Ball, B; Chapman, J W; Dai, T; Ferretti, C; Gregory, J [University of Michigan, Department of Physics, Ann Arbor, MI (United States); Beretta, M [INFN Laboratori Nazionali di Frascati, Frascati (Italy); Boterenbrood, H; Jansweijer, P P M [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands); Brandenburg, G W; Fries, T; Costa, J Guimaraes da; Harder, S; Huth, J [Harvard University, Laboratory for Particle Physics and Cosmology, Cambridge, MA (United States); Ceradini, F [INFN Roma Tre and Universita Roma Tre, Dipartimento di Fisica, Roma (Italy); Hazen, E [Boston University, Physics Department, Boston, MA (United States); Kirsch, L E [Brandeis University, Department of Physics, Waltham, MA (United States); Koenig, A C [Radboud University Nijmegen/Nikhef, Dept. of Exp. High Energy Physics, Nijmegen (Netherlands); Lanza, A [INFN Pavia, Pavia (Italy); Mikenberg, G [Weizmann Institute of Science, Department of Particle Physics, Rehovot (Israel)], E-mail: brandenburg@physics.harvard.edu (and others)

    2008-09-15

    This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta of muon tracks to an accuracy of 60 {mu}m, which corresponds to a momentum accuracy of about 10% at p{sub T}= 1 TeV. The design and performance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under simulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

  11. ATLAS Muon Drift Tube Electronics

    CERN Document Server

    Arai, Y; Beretta, M; Boterenbrood, H; Brandenburg, G W; Ceradini, F; Chapman, J W; Dai, T; Ferretti, C; Fries, T; Gregory, J; Guimarães da Costa, J; Harder, S; Hazen, E; Huth, J; Jansweijer, P P M; Kirsch, L E; König, A C; Lanza, A; Mikenberg, G; Oliver, J; Posch, C; Richter, R; Riegler, W; Spiriti, E; Taylor, F E; Vermeulen, J; Wadsworth, B; Wijnen, T A M

    2008-01-01

    This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta of muon tracks to an accuracy of 60 microns, which corresponds to a momentum accuracy of about 10% at pT = 1 TeV. The design and performance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under simulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

  12. A Pascalian lateral drift sensor

    International Nuclear Information System (INIS)

    Jansen, H.

    2016-01-01

    A novel concept of a layer-wise produced semiconductor sensor for precise particle tracking is proposed herein. In contrast to common semiconductor sensors, local regions with increased doping concentration deep in the bulk termed charge guides increase the lateral drift of free charges on their way to the read-out electrode. This lateral drift enables charge sharing independent of the incident position of the traversing particle. With a regular grid of charge guides the lateral charge distribution resembles a normalised Pascal's triangle for particles that are stopped in depths lower than the depth of the first layer of the charge guides. For minimum ionising particles a sum of binomial distributions describes the lateral charge distribution. This concept decouples the achievable sensor resolution from the pitch size as the characteristic length is replaced by the lateral distance of the charge guides.

  13. A Pascalian lateral drift sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, H., E-mail: hendrik.jansen@desy.de

    2016-09-21

    A novel concept of a layer-wise produced semiconductor sensor for precise particle tracking is proposed herein. In contrast to common semiconductor sensors, local regions with increased doping concentration deep in the bulk termed charge guides increase the lateral drift of free charges on their way to the read-out electrode. This lateral drift enables charge sharing independent of the incident position of the traversing particle. With a regular grid of charge guides the lateral charge distribution resembles a normalised Pascal's triangle for particles that are stopped in depths lower than the depth of the first layer of the charge guides. For minimum ionising particles a sum of binomial distributions describes the lateral charge distribution. This concept decouples the achievable sensor resolution from the pitch size as the characteristic length is replaced by the lateral distance of the charge guides.

  14. MPS II drift chamber system

    International Nuclear Information System (INIS)

    Platner, E.D.

    1982-01-01

    The MPS II detectors are narrow drift space chambers designed for high position resolution in a magnetic field and in a very high particle flux environment. Central to this implementation was the development of 3 multi-channel custom IC's and one multi-channel hybrid. The system is deadtimeless and requires no corrections on an anode-to-anode basis. Operational experience and relevance to ISABELLE detectors is discussed

  15. Shear wall ultimate drift limits

    International Nuclear Information System (INIS)

    Duffey, T.A.; Goldman, A.; Farrar, C.R.

    1994-04-01

    Drift limits for reinforced-concrete shear walls are investigated by reviewing the open literature for appropriate experimental data. Drift values at ultimate are determined for walls with aspect ratios ranging up to a maximum of 3.53 and undergoing different types of lateral loading (cyclic static, monotonic static, and dynamic). Based on the geometry of actual nuclear power plant structures exclusive of containments and concerns regarding their response during seismic (i.e.,cyclic) loading, data are obtained from pertinent references for which the wall aspect ratio is less than or equal to approximately 1, and for which testing is cyclic in nature (typically displacement controlled). In particular, lateral deflections at ultimate load, and at points in the softening region beyond ultimate for which the load has dropped to 90, 80, 70, 60, and 50 percent of its ultimate value, are obtained and converted to drift information. The statistical nature of the data is also investigated. These data are shown to be lognormally distributed, and an analysis of variance is performed. The use of statistics to estimate Probability of Failure for a shear wall structure is illustrated

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

    Science.gov (United States)

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

    2013-04-01

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

  17. Optimal Transmission Line Switching under Geomagnetic Disturbances

    International Nuclear Information System (INIS)

    Lu, Mowen; Nagarajan, Harsha; Yamangil, Emre; Bent, Russell; Backhaus, Scott

    2017-01-01

    Recently, there have been increasing concerns about how geomagnetic disturbances (GMDs) impact electrical power systems. Geomagnetically-induced currents (GICs) can saturate transformers, induce hot spot heating and increase reactive power losses. These effects can potentially cause catastrophic damage to transformers and severely impact the ability of a power system to deliver power. To address this problem, we develop a model of GIC impacts to power systems that includes 1) GIC thermal capacity of transformers as a function of normal Alternating Current (AC) and 2) reactive power losses as a function of GIC. We also use this model to derive an optimization problem that protects power systems from GIC impacts through line switching, generator dispatch, and load shedding. We then employ state-of-the-art convex relaxations of AC power flow equations to lower bound the objective. We demonstrate the approach on a modified RTS96 system and UIUC 150-bus system and show that line switching is an effective means to mitigate GIC impacts. We also provide a sensitivity analysis of decisions with respect to GMD direction.

  18. Resolving issues concerning Eskdalemuir geomagnetic hourly values

    Directory of Open Access Journals (Sweden)

    S. Macmillan

    2011-02-01

    Full Text Available The hourly values of the geomagnetic field from 1911 to 1931 derived from measurements made at Eskdalemuir observatory in the UK, and available online from the World Data Centre for Geomagnetism at http://www.wdc.bgs.ac.uk/, have now been corrected. Previously they were 2-point averaged and transformed from the original north, east and vertical down values in the tables in the observatory yearbooks. This paper documents the course of events from discovering the post-processing done to the data to the final resolution of the problem. As it was through the development of a new index, the Inter-Hour Variability index, that this post-processing came to light, we provide a revised series of this index for Eskdalemuir and compare it with that from another European observatory. Conclusions of studies concerning long-term magnetic field variability and inferred solar variability, whilst not necessarily consistent with one another, are not obviously invalidated by the incorrect hourly values from Eskdalemuir. This series of events illustrates the challenges that lie ahead in removing any remaining errors and inconsistencies in the data holdings of different World Data Centres.

  19. Atmospheric helium and geomagnetic field reversals.

    Science.gov (United States)

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

    1972-01-01

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

  20. Geomagnetic storm effects on GPS based navigation

    Directory of Open Access Journals (Sweden)

    P. V. S. Rama Rao

    2009-05-01

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

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

  1. Geomagnetic control of polar mesosphere summer echoes

    Directory of Open Access Journals (Sweden)

    J. Bremer

    2000-02-01

    Full Text Available Using observations with the ALOMAR SOUSY radar near Andenes (69.3°N, 16.0°E from 1994 until 1997 polar mesosphere summer echoes (PMSE have been investigated in dependence on geomagnetic K indices derived at the Auroral Observatory Tromsø (69.66°N, 18.94°E. During night-time and morning hours a significant correlation between the signal-to-noise ratio (SNR of the radar results and the geomagnetic K indices could be detected with a maximum correlation near midnight. The correlation becomes markedly smaller in the afternoon and early evening hours with a minimum near 17 UT. This diurnal variation is in reasonable agreement with riometer absorption at Ivalo (68.55°N, 27.28°E and can be explained by the diurnal variation of ionization due to precipitating high energetic particles. Therefore, a part of the diurnal PMSE variation is caused by this particle precipitation. The variability of the solar EUV variation, however, has no significant influence on the PMSE during the observation period.Keywords: Ionosphere (auroral ionosphere - Magnetospheric physics (energetic particles, precipitating - Radio science (remote sensing

  2. Plasmaspheric noise radiation during geomagnetic storms

    International Nuclear Information System (INIS)

    Larkina, V.I.; Likhter, Ya.I.

    1981-01-01

    Variations of plasmospheric background radiations during geomagnetic storms of different intensity are investigated. Used are results of ELF and VLF radiation measurements as well as electron fluxes of energies Esub(e)>40 keV carried out by Intercosmos 3 and Intercosmos 5 satellites. Dependences of radiation amplitude variations at 1.6 and 25 kHz frequencies on L shell for various geomagnetic activity in the day-time as well as data on variations of quasicaptured electron fluxes at Esub(e)>40 keV, are given. It is shown that experimental data agree with the existing theories of plasmospheric noise excitation. It is concluded that the plasmospheric noise excitation area Lsub(max) is always in the region of gap between radiation belts and inner slope of external radiation belt during magnetic storms. During magnetic storms Lsub(max) area moves simultaneously with the area, where particle flux of the external radiation belt is the most intensive [ru

  3. Solar Wind Charge Exchange During Geomagnetic Storms

    Science.gov (United States)

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

    2012-01-01

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

  4. Geomagnetically trapped carbon, nitrogen, and oxygen nuclei.

    Science.gov (United States)

    Mogro-Campero, A.

    1972-01-01

    Results of measurements carried out with the University of Chicago nuclear composition telescope on the Ogo 5 satellite, establishing the presence of 13- to 33-MeV/nucleon geomagnetically trapped C and O nuclei, with some evidence for N nuclei. These trapped nuclei were found at L less than or equal to 5 and near the geomagnetic equator. The data cover the period from Mar. 3, 1968, to Dec. 31, 1969. The distribution of CNO flux as a function of L is given. No change in the intensity of the average trapped CNO flux was detected by comparing data for 1968 and 1969. The results reported set a new value for the observed high energy limit of trapping as described by the critical adiabaticity parameter. The penetration of solar flare CNO up to L = 4 was observed twice in 1968, in disagreement with Stormer theory predictions. The effects of these results on some models for the origin of the trapped radiation are discussed.

  5. Three-dimensional current flow and particle precipitation in a westward travelling surge (observed during the barium-GEOS rocket experiment)

    International Nuclear Information System (INIS)

    Opgenoorth, H.J.; Pellinen, R.J.; Baumjohann, W.; Nielsen, E.; Marklund, G.; Eliasson, L.

    1983-01-01

    During the Barium-GEOS rocket experiment on September 24, 1979 the passage of a westward travelling surge (WTS) was observed over Scandinavia. Extended instrument networks in that area, viz., the Scandinavian Magnetometer Array, the STARE radars, all-sky cameras, and riometers, allowed simultaneous observation of the two-dimensional character of magnetic and electric field disturbances and particle precipitation associated with the auroral feature. By combination of the different datasets and additional information from particle and electric field measurements aboard the Barium-GEOS rocket it was possible to derive the two-dimensional distribution of ionospheric electric fields and conductivities and to model the three-dimensional current flow in the vicinity of the westward travelling surge. The main feature of the resulting model current system is the presence of a localized upward field-aligned current directed out of the head of the surge and fed by a westward electrojet, which is composed of both Hall and Pedersen currents. Secondary ionospheric currents, e.g. a counterclockwise loop of mainly Hall currents around the leading edge of the surge, are found to be responsible for most of the transient effects observed by ground-based magnetometers as the WTS passed overhead. The most energetic particle precipitation as inferred from cosmic noise absorption measurements and triangulation of auroral arc altitudes is found to be confined to the leading part and central regions of the surge and to travel westward with the visual auroral form

  6. Optimization of drift gases for accuracy in pressurized drift tubes

    CERN Document Server

    Kirchner, J J; Dinner, A R; Fidkowski, K J; Wyatt, J H

    2001-01-01

    Modern detectors such as ATLAS use pressurized drift tubes to minimize diffusion and achieve high coordinate accuracy. However, the coordinate accuracy depends on the exact knowledge of converting measured times into coordinates. Linear space-time relationships are best for reconstruction, but difficult to achieve in the $E \\propto \\frac{1}{r}$ field. Previous mixtures, which contained methane or other organic quenchers, are disfavored because of ageing problems. From our studies of nitrogen and carbon dioxide, two mixtures with only small deviations from linearity were determined and measured. Scaling laws for different pressures and magnetic fields are also given.

  7. Optimization of drift gases for accuracy in pressurized drift tubes

    International Nuclear Information System (INIS)

    Kirchner, J.J.; Becker, U.J.; Dinner, R.B.; Fidkowski, K.J.; Wyatt, J.H.

    2001-01-01

    Modern detectors such as ATLAS use pressurized drift tubes to minimize diffusion and achieve high coordinate accuracy. However, the coordinate accuracy depends on the exact knowledge of converting measured times into coordinates. Linear space-time relationships are best for reconstruction, but difficult to achieve in the E∝1/r field. Previous mixtures, which contained methane or other organic quenchers, are disfavored because of ageing problems. From our studies of nitrogen and carbon dioxide, two mixtures with only small deviations from linearity were determined and measured. Scaling laws for different pressures and magnetic fields are also given

  8. Geomagnetic response to solar and interplanetary disturbances

    Directory of Open Access Journals (Sweden)

    Maris Georgeta

    2013-07-01

    Full Text Available The space weather discipline involves different physical scenarios, which are characterised by very different physical conditions, ranging from the Sun to the terrestrial magnetosphere and ionosphere. Thanks to the great modelling effort made during the last years, a few Sun-to-ionosphere/thermosphere physics-based numerical codes have been developed. However, the success of the prediction is still far from achieving the desirable results and much more progress is needed. Some aspects involved in this progress concern both the technical progress (developing and validating tools to forecast, selecting the optimal parameters as inputs for the tools, improving accuracy in prediction with short lead time, etc. and the scientific development, i.e., deeper understanding of the energy transfer process from the solar wind to the coupled magnetosphere-ionosphere-thermosphere system. The purpose of this paper is to collect the most relevant results related to these topics obtained during the COST Action ES0803. In an end-to-end forecasting scheme that uses an artificial neural network, we show that the forecasting results improve when gathering certain parameters, such as X-ray solar flares, Type II and/or Type IV radio emission and solar energetic particles enhancements as inputs for the algorithm. Regarding the solar wind-magnetosphere-ionosphere interaction topic, the geomagnetic responses at high and low latitudes are considered separately. At low latitudes, we present new insights into temporal evolution of the ring current, as seen by Burton’s equation, in both main and recovery phases of the storm. At high latitudes, the PCC index appears as an achievement in modelling the coupling between the upper atmosphere and the solar wind, with a great potential for forecasting purposes. We also address the important role of small-scale field-aligned currents in Joule heating of the ionosphere even under non-disturbed conditions. Our scientific results in

  9. Measurement of the positron-drift time relation of a high-pressure drift chamber

    International Nuclear Information System (INIS)

    Pruefert, W.

    1989-04-01

    As a test of its performance, the measurement of the drift time versus drift distance relation of a high pressure drift chamber using cosmic rays is described. Two multiwire proportional chambers, mounted above and below the detector, are used to define the track of the cosmic particle in the drift chamber. The drift chamber is read out by FADCs (Flash Analog to Digital Converter), and the drift time is determined from the FADC signals by the DOS- (Difference Of Samples) method. The measured drift time versus drift distance relation showed good agreement with the relation, which is expected from the spatial dependence of the electric field and the dependence of the drift velocity on this field. (orig.) [de

  10. Pulse shape simulation for drift chambers with long drift paths

    International Nuclear Information System (INIS)

    Mayer, H.J.

    1987-01-01

    A detailed Monte Carlo program for the simulation of drift chamber pulse shapes is described. It has been applied to the case of a jet chamber with drift paths up to 24 cm. Results on pulse shapes and corresponding spatial and double hit resolution are discussed and compared to recent measurements of the OPAL central detector jet chamber full size prototype and to measurements of a small 20-wire prototype, which was designed to study the pulse shapes generated by tracks in a magnetic field. Simulated pulse shapes and spatial resolutions agree well with the experimental data. Clustering, saturation and wire crosstalk are shown to be necessary ingredients in the simulation. A deterioration in resolution due to the influence of crosstalk signals is correctly reproduced, as well as the cancellation of this effect by a hardwired first and second neighbour crosstalk compensation. The simulation correctly describes the asymmetry in spatial resolution observed for tracks with positive or negative inclination against the wire plane when a magnetic field is present. The effect of saturation on double hit resolution is found to be small. The magnetic field is predicted to improve the double hit resolution. (orig.)

  11. Pulse shape simulation for drift chambers with long drift paths

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, H J

    1987-09-15

    A detailed Monte Carlo program for the simulation of drift chamber pulse shapes is described. It has been applied to the case of a jet chamber with drift paths up to 24 cm. Results on pulse shapes and corresponding spatial and double hit resolution are discussed and compared to recent measurements of the OPAL central detector jet chamber full size prototype and to measurements of a small 20-wire prototype, which was designed to study the pulse shapes generated by tracks in a magnetic field. Simulated pulse shapes and spatial resolutions agree well with the experimental data. Clustering, saturation and wire crosstalk are shown to be necessary ingredients in the simulation. A deterioration in resolution due to the influence of crosstalk signals is correctly reproduced, as well as the cancellation of this effect by a hardwired first and second neighbour crosstalk compensation. The simulation correctly describes the asymmetry in spatial resolution observed for tracks with positive or negative inclination against the wire plane when a magnetic field is present. The effect of saturation on double hit resolution is found to be small. The magnetic field is predicted to improve the double hit resolution.

  12. Global Ultra-Low-Frequency Geomagnetic Pulsations Associated with the March 24, 1991 Geomagnetic Storm

    Directory of Open Access Journals (Sweden)

    Nan-Wei Chen Jann-Yenq Liu

    2008-01-01

    Full Text Available On 24 March 1991, global ultra-low-frequency (ULF pulsations (1.1 - 3.3 mHz observed in the magnetosphere as well as on the ground were studied via analyzing magnetic field data obtained from a global network, comprising ground-based observatories and geosynchronous satellites. In the magnetosphere, the compressional and transverse components of the magnetic fields recorded at two satellites, GOES 6 and GOES 7, showed dominant fluctuations when they were in the vicinity of the noon sector, whereas the transverse fluctuations became dominant when they were at the dawn side. Similarly, on the ground, the H and D components had major fluctuations along with an increase in amplitude from low to high geomagnetic latitudes. In addition, the amplitude of the ULF pulsation was enhanced at the dawn and dusk sides. The geomagnetic pulsations propagated anti-sunward and were of counterclockwise and clockwise elliptical polarizations at the dawn and dusk sides respectively. The counterclockwise elliptical polarization reversed to a clockwise elliptical polarization at geomagnetic local noon and linear polarization was observed during the reversal. It appears that the analysis of the global network data not only provided us with a study of the characteristics of the waves in the magnetosphere and on the ground but also provided us with correlations between the geosynchronous and ground observations, which should be essential to the determination of possible mechanisms of this storm-related wave event.

  13. Drift waves in a stellarator

    International Nuclear Information System (INIS)

    Bhattacharjee, A.; Sedlak, J.E.; Similon, P.L.; Rosenbluth, M.N.; Ross, D.W.

    1982-11-01

    We investigate the eigenmode structure of drift waves in a straight stellarator using the ballooning mode formalism. The electrons are assumed to be adiabatic and the ions constitute a cold, magnetized fluid. The effective potential has an overall parabolic envelope but is modulated strongly by helical ripples along B. We have found two classes of solutions: those that are strongly localized in local helical wells, and those that are weakly localized and have broad spatial extent. The weakly localized modes decay spatially due to the existence of Mathieu resonances between the periods of the eigenfunction and the effective potential

  14. Kinetic theory of drift waves

    International Nuclear Information System (INIS)

    Vlad, G.

    1988-01-01

    The linear stability of the electrostatic drift waves in slab geometry has been studied analytically and numerically. The effects of magnetic field with shear, of the finite Larmor radius, of an electron streaming, of a temperature gradient and of collisions have been retained. The analytical solution has been obtained using the matched asymptotic expansion technique, and an expression for the critical streaming parameter has been derived. Finally, assuming that the transport in the Reversed Field Pinches is dominated by this instability, a scaling law for the temperature in such machine is derived

  15. Experimental work on drift chambers

    International Nuclear Information System (INIS)

    Alcaraz, J.; Duran, I.; Gonzalez, E.; Martinez-Laso, L.; Olmos, P.

    1989-01-01

    An experimental work made on drift chambers is described in two chapters. In the firt chapter we present the description of the experimental installation used, as well as some details on the data adquisition systems and the characteristics on three ways used for calibration proposes (cosmic muons, β radiation and test beam using SPS at CERN facilities). The second chapter describes the defferent prototypes studied. The experimental set up and the analysis are given. Some results are discussed. The magnetic field effect is also studied. (Author)

  16. Drift vortices in continuous media

    International Nuclear Information System (INIS)

    Chernousenko, V.M.; Chernenko, I.V.; Chernyshenko, S.V.

    1989-01-01

    The work is devoted to investigation into the problems of large-scale cortex drift and generation in continuous media based on the solution of notably non-linear differential equations. Using the capability of the modern computer technique it is possible to consider a series of cases with regard to medium viscosity and its inhomogeneity and with regard to three-dimensional vortex nature. Based on the solutions obtained the large-scale steady-state vortex generation processes are considered. The results can be used when studying non-linear phenomena in plasma and processes of substance and energy transfer in non-equilibrium media. 16 refs.; 5 figs

  17. Statistical Study of False Alarms of Geomagnetic Storms

    DEFF Research Database (Denmark)

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

    . A subset of these halo CMEs did not cause a geomagnetic storm the following four days and have therefore been considered as false alarms. The properties of these events are investigated and discussed here. Their statistics are compared to the geo-effective CMEs. The ability to identify potential false......Coronal Mass Ejections (CMEs) are known to cause geomagnetic storms on Earth. However, not all CMEs will trigger geomagnetic storms, even if they are heading towards the Earth. In this study, front side halo CMEs with speed larger than 500 km/s have been identified from the SOHO LASCO catalogue...

  18. GEOMAGNETIC CONJUGACY OF MODERN TECTONIC STRUCTURES

    Directory of Open Access Journals (Sweden)

    G. Ya. Khachikyan

    2013-01-01

    Full Text Available An earthquake is an element of the global electric circuit (GEC –  this new idea suggested in the space age is tested in our study. In the frame of the GEC concept, one may expect that tectonic structures of the northern and southern hemispheres may be magnetically conjugated. It is found that the midocean ridges of the southern hemisphere, located along the boundary of the Antarctic lithosphere plate, are magnetically conjugated with the areas of the junction of continental orogens and platforms in the northern hemisphere. The closest geomagnetic conjugacy exists between the southern boundary of Nazca lithospheric plate and the northern boundaries of Cocos and Caribbean lithospheric plates.

  19. Extreme Geomagnetic Storms – 1868–2010

    DEFF Research Database (Denmark)

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

    2016-01-01

    presents our investigation of the corresponding solar eventsand 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 areanalyzed statistically in the context of more well...... occurring in May 1921 and the Quebec storm from March 1989. We identifykey characteristics of the storms by combining several different available data sources, listsof storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks,solar wind in-situ measurements, neutron monitor data...... %), Forbushdecreases (100 %), and energetic solar proton events (70 %). A quantitative comparison ofthese associations relative to less intense storms is also presented. Most notably, we findthat most often the extreme storms are characterized by a complexity that is associated with multiple, often interacting, solar...

  20. Regional Forecasting of Wind Speeds during Typhoon Landfall in Taiwan: A Case Study of Westward-Moving Typhoons

    Directory of Open Access Journals (Sweden)

    Chih-Chiang Wei

    2018-04-01

    Full Text Available Taiwan is located on a route where typhoons often strike. Each year, the strong winds accompanying typhoons are a substantial threat and cause significant damage. However, because the terrains of high mountains in Taiwan vary greatly, when a typhoon passes the Central Mountain Range (CMR, the wind speed of typhoons becomes difficult to predict. This research had two primary objectives: (1 to develop data-driven techniques and a powerful artificial neural network (ANN model to predict the highly complex nonlinear wind systems in western Taiwan; and, (2 to investigate the accuracy of wind speed predictions at various locations and for various durations in western Taiwan when the track of westward typhoons is affected by the complex geographical shelters and disturbances of the CMR. This study developed a typhoon wind speed prediction model that evaluated various typhoon tracks (covering Type 2, Type 3, and Type 4 tracks, as defined by the Central Weather Bureau, and evaluated the prediction accuracy at Hsinchu, Wuqi, and Kaohsiung Stations in western Taiwan. Back propagation neural networks (BPNNs were employed to establish wind speed prediction models, and a linear regression model was adopted as the benchmark to evaluate the strengths and weaknesses of the BPNNs. The results were as follows: (1 The BPNNs generally had favorable performance in predicting wind speeds and their performances were superior to linear regressions; (2 when absolute errors were adopted to evaluate the prediction performances, the predictions at Hsinchu Station were the most accurate, whereas those at Wuqi Station were the least accurate; however, when relative errors were adopted, the predictions at Hsinchu Station were again the most accurate, whereas those at Kaohsiung were the least accurate; and, (3 regarding the relative error rates for the maximum wind speed of Types 2, 3, and 4 typhoons, Wuqi, Kaohsiung, and Wuqi had the most accurate performance, respectively; as

  1. Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch

    Directory of Open Access Journals (Sweden)

    Mario Brkić

    2013-12-01

    Full Text Available After more than half a century, scientific book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch describes the recent geomagnetic field on Croatian territory. A review of research in the past decade as well as the original solutions makes the book a document of contribution to geodesy and geomagnetism in Croatia.The book’s introduction gives an overview of two centuries of history and the strategic, security, economic and scientific significance of knowing the geomagnetic field on the Croatian territory. All the activities related to the updating of the geomagnetic information, which took place in the last decade, signified a big step toward the countries where geomagnetic survey is a mature scientific and technical discipline, and a scientific contribution to understanding of the nature of the Earth's magnetism.The declination, inclination and total intensity maps (along with the normal annual changes for the epoch 2009.5 are given in the Appendix. The book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch (ISBN 978-953-293-521-9 is published by the State Geodetic Administration of the Republic of Croatia. Beside editor in chief, M. Brkić, the authors are: E. Vujić, D. Šugar, E. Jungwirth, D. Markovinović, M. Rezo, M. Pavasović, O. Bjelotomić, M. Šljivarić, M. Varga and V. Poslončec-Petrić. The book contains 48 pages and 3 maps, and is published in 200 copies. CIP record is available in digital catalogue of the National and University Library in Zagreb under number 861937.

  2. Drift-time measurement electronics

    International Nuclear Information System (INIS)

    Pernicka, M.

    1978-01-01

    The aim of the construction was to improve the time resolution without using the facility of time stretching, to have a fast read-out possibility, and to be still cheaper in price in comparison to other systems. A possibility was thus foreseen for using the firm Fairchild. These integrated circuits (IC) have, for example, a propagation delay of 0.75 ns for a gate. One can expect therefore less time jitter and less time difference between the different inputs. Furthermore this IC offers a greater flexibility and therefore the number of ICs decreases and distances become smaller. Working with clock frequencies up to 166.6 MHz is easily possible without running into timing problems. On the other hand, to make full use of the advantages of this IC, it was necessary to build the print as a multilayer. The only risk could be in the use of a completely new product. A further aim was to build for this system a second type of drift-time module with a short time range for measuring drift time and pulse length in rotated multiwire proportional chambers. A brief outline of the specifications of the different modules is given in table 1. (Auth.)

  3. High-speed and supersonic upward plasma drifts: multi-instrumental study

    Science.gov (United States)

    Astafyeva, E.; Zakharenkova, I.; Hairston, M. R.; Huba, J.; Coley, W. R.

    2017-12-01

    Since the pioneering observations by Aggson et al. (1992, JGR, doi: 10.1002/92JA00644), there have been several reports of the occurrence of high-speed (Vz>800 m/s) and supersonic plasma flows in the post-sunset (e.g., Hysell et al., 1994, JGR, doi: 10.1029/94JA00476; Hanson et al., 1997, JGR, doi: 10.1029/96JA03376) and the pre-dawn sector (Astafyeva and Zakharenkova, 2015, GRL, doi:10.1002/2015GL066369). However, despite this observational evidence, these events remain rare and are not well understood. The main issue is to determine the background conditions leading to the occurrence of these high-speed plasma drifts. In this work, we perform a multi-instrumental study of high-speed and supersonic upward plasma drift events/structures. For this purpose, we analyze data from several ground-based and space-borne instruments, including data from the DMSP, Swarm and C/NOFS (IVM instrument) satellites. In addition to the space-borne instruments, we use data from ground-based GPS-receivers and ionosondes to further investigate the background ionosphere conditions, as well as the effects produced by the plasma bubbles and ionospheric irregularities. Besides the observations, we add the SAMI3/ESF modeling results on plasma bubble simulations and high-speed drifts inside plasma bubbles. TIE-GCM runs (from the CCMC, https://ccmc.gsfc.nasa.gov) are used to define the background atmospheric/ionospheric and electrodynamical conditions leading to the occurrence of the high-speed and supersonic plasma drift events. Our search of events with upward plasma drift exceeding 800 m/s in the data of DMSP for the years 2002-2016 shows that such high-speed events are extremely rare. During this period of time, only 6 events were found, two of them occurred during the recovery phase of a geomagnetic storm, while the other four were detected during geomagnetically quiet conditions. Concerning the generation of such events, our preliminary results show that enhanced electric fields are

  4. The large cylindrical drift chamber of TASSO

    International Nuclear Information System (INIS)

    Boerner, H.; Fischer, H.M.; Hartmann, H.; Loehr, B.; Wollstadt, M.; Fohrmann, R.; Schmueser, P.; Cassel, D.G.; Koetz, U.; Kowalski, H.

    1980-03-01

    We have built and operated a large cylindrical drift chamber for the TASSO experiment at the DESY storage ring, PETRA. The chamber has a length of 3.5 m, a diameter of 2.5 m, and a total of 2340 drift cells. The cells are arranged in 15 concentric layers such that tracks can be reconstructed in three dimensions. A spatial resolution of 220 μm has been achieved for tracks of normal incidence on the drift cells. (orig.)

  5. Drift chamber tracking with neural networks

    International Nuclear Information System (INIS)

    Lindsey, C.S.; Denby, B.; Haggerty, H.

    1992-10-01

    We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed

  6. Electron injection in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Castoldi, A.; Vacchi, A.

    1990-01-01

    The paper reports the first successful results of a simple MOS structure to inject electrons at a given position in Silicon Drift Detectors. The structure allows on-line calibration of the drift velocity of electrons within the detector. The calibration is a practical method to trace the temperature dependence of the electron mobility. Several of these injection structures can be implemented in silicon drift detectors without additional steps in the fabrication process. 5 refs., 11 figs

  7. Cooling tower drift: comprehensive case study

    International Nuclear Information System (INIS)

    Laulainen, N.S.; Ulanski, S.L.

    1979-01-01

    A comprehensive experiment to study drift from mechanical drift cooling towers was conducted during June 1978 at the PG and E Pittsburg Power Plant. The data from this study will be used for validation of drift deposition models. Preliminary results show the effects of tower geometry and orientation with respect to the wind and to single- or two-tower operation. The effect of decreasing relative humidity during a test run can also be seen

  8. Effects of geomagnetic storm on low latitude ionospheric total ...

    Indian Academy of Sciences (India)

    1Department of Physics, Tripura University, Suryamaninagar, Tripura 799 022, India. ... the fact that the electro-dynamic effect of geomagnetic storms around EIA region is more effective than ... causes range of error in GPS communication.

  9. Research on Stealthy Headphone Detector Based on Geomagnetic Sensor

    Directory of Open Access Journals (Sweden)

    Liu Ya

    2016-01-01

    Full Text Available A kind of stealth headphone detector based on geomagnetic sensor has been developed to deal with the stealth headphones which are small, extremely stealthy and hard to detect. The U.S. PNI geomagnetic sensor is chosen to obtain magnetic field considering the strong magnetic performance of stealth headphones. The earth’s magnetic field at the geomagnetic sensor is eliminated by difference between two geomagnetic sensors, and then weak variations of magnetic field is detected. STM8S103K2 is chosen as the central controlling chip, which is connected to LED, buzzer and LCD 1602. As shown by the experimental results, the probe is not liable to damage by the magnetic field and the developed device has high sensitivity, low False Positive Rate (FAR and satisfactory reliability.

  10. A comprehensive analysis of the geomagnetic storms occurred dur

    Directory of Open Access Journals (Sweden)

    Essam Ghamry

    2016-06-01

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

  11. A Probabilistic Assessment of the Next Geomagnetic Reversal

    Science.gov (United States)

    Buffett, Bruce; Davis, William

    2018-02-01

    Deterministic forecasts for the next geomagnetic reversal are not feasible due to large uncertainties in the present-day state of the Earth's core. A more practical approach relies on probabilistic assessments using paleomagnetic observations to characterize the amplitude of fluctuations in the geomagnetic dipole. We use paleomagnetic observations for the past 2 Myr to construct a stochastic model for the axial dipole field and apply well-established methods to evaluate the probability of the next geomagnetic reversal as a function of time. For a present-day axial dipole moment of 7.6 × 1022 A m2, the probability of the dipole entering a reversed state is less than 2% after 20 kyr. This probability rises to 11% after 50 kyr. An imminent geomagnetic reversal is not supported by paleomagnetic observations. The current rate of decline in the dipole moment is unusual but within the natural variability predicted by the stochastic model.

  12. An Impending geomagnetic transition? Hints from the past.

    Directory of Open Access Journals (Sweden)

    Carlo eLAJ

    2015-10-01

    Full Text Available The rapid decrease of the geomagnetic field intensity in the last centuries has led to speculations that an attempt to a reversal or an excursion might be under way. Here we investigate this hypothesis by examining past records of geomagnetic field intensity obtained from sedimentary cores and from the study of cosmogenic nuclides. The selected records describe geomagnetic changes with an unprecedented temporal resolution between 20 and 75 kyr B.P. We find that some aspects of the present-day geomagnetic field have some similarities with those documented for the Laschamp excursion 41 kyr ago. Under the assumption that the dynamo processes for an eventual future reversal or excursion would be similar to those of the Laschamp excursion, we tentatively suggest that, whilst irreversible processes that will drive the geodynamo into a polarity change may have already started, a reversal or an excursion should not be expected before 500 to 1000 years.

  13. Geomagnetic field models for satellite angular motion studies

    Science.gov (United States)

    Ovchinnikov, M. Yu.; Penkov, V. I.; Roldugin, D. S.; Pichuzhkina, A. V.

    2018-03-01

    Four geomagnetic field models are discussed: IGRF, inclined, direct and simplified dipoles. Geomagnetic induction vector expressions are provided in different reference frames. Induction vector behavior is compared for different models. Models applicability for the analysis of satellite motion is studied from theoretical and engineering perspectives. Relevant satellite dynamics analysis cases using analytical and numerical techniques are provided. These cases demonstrate the benefit of a certain model for a specific dynamics study. Recommendations for models usage are summarized in the end.

  14. A Probabilistic Assessment of the Next Geomagnetic Reversal

    OpenAIRE

    Buffett, B; Davis, W

    2018-01-01

    ©2018. American Geophysical Union. All Rights Reserved. Deterministic forecasts for the next geomagnetic reversal are not feasible due to large uncertainties in the present-day state of the Earth's core. A more practical approach relies on probabilistic assessments using paleomagnetic observations to characterize the amplitude of fluctuations in the geomagnetic dipole. We use paleomagnetic observations for the past 2 Myr to construct a stochastic model for the axial dipole field and apply wel...

  15. Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

    OpenAIRE

    Linssen, J.H.

    1991-01-01

    In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its variations are recorded in rocks as a natural remanent magnetization (NRM) during the formation of these rocks. The study of the NRM in sedimentary reversal records is the subject of this dissertation.

  16. Construction update and drift velocity calibration for the CLAS drift chamber system

    International Nuclear Information System (INIS)

    Mestayer, M.D.; Barbosa, F.J.; Bonneau, P.; Burtin, E.; Christo, S.; Doolittle, G.; Dytman, S.A.; Gilfoyle, G.P.; Hyde-Wright, C.E.; Klein, A.; Kossov, M.V.; Kuhn, S.E.; Magahiz, R.; Miskimen, R.A.; Murphy, L.Y.; O'Meara, J.E.; Pyron, T.D.; Qin, L.; Raue, B.A.; Schumacher, R.A.; Tuzel, W.; Weinstein, L.B.; Yegneswaran, A.

    1995-01-01

    We briefly describe the drift chamber system for the CLAS detector at CEBAF, concentrating on the method which will be used to calibrate the drift velocity function. We identify key features of the function which should apply to any small-cell drift chamber geometry in which the cathode and anode surfaces are wires. Using these ideas, we describe a simple method to compensate for variations in the drift velocity function due to environmental changes. (orig.)

  17. Construction update and drift velocity calibration for the CLAS drift chamber system

    Energy Technology Data Exchange (ETDEWEB)

    Mestayer, M.D. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Barbosa, F.J. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Bonneau, P. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Burtin, E. [University of South Carolina, Columbia, SC (United States); Christo, S. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Doolittle, G. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Dytman, S.A. [University of Pittsburg, Pittsburg, PA (United States); Gilfoyle, G.P. [University of Richmond, Richmond, VA (United States); Hyde-Wright, C.E. [Old Dominion University, Norfolk, VA (United States); Klein, A. [Old Dominion University, Norfolk, VA (United States); Kossov, M.V. [Christopher Newport University, Newport News, VA (United States); Kuhn, S.E. [Old Dominion University, Norfolk, VA (United States); Magahiz, R. [Carnegie-Mellon Univ., Pittsburgh, PA (United States); Miskimen, R.A. [University of Massachussetts, Amherst, MA (United States); Murphy, L.Y. [CE Saclay, Gif sur Yvette (France); O`Meara, J.E. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Pyron, T.D. [Old Dominion University, Norfolk, VA (United States); Qin, L. [Old Dominion University, Norfolk, VA (United States); Raue, B.A. [Old Dominion University, Norfolk, VA (United States); Schumacher, R.A. [Carnegie-Mellon Univ., Pittsburgh, PA (United States); Tuzel, W. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Weinstein, L.B. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Yegneswaran, A. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)

    1995-12-11

    We briefly describe the drift chamber system for the CLAS detector at CEBAF, concentrating on the method which will be used to calibrate the drift velocity function. We identify key features of the function which should apply to any small-cell drift chamber geometry in which the cathode and anode surfaces are wires. Using these ideas, we describe a simple method to compensate for variations in the drift velocity function due to environmental changes. (orig.).

  18. Electron drift time in silicon drift detectors: A technique for high precision measurement of electron drift mobility

    International Nuclear Information System (INIS)

    Castoldi, A.; Rehak, P.

    1995-01-01

    This paper presents a precise absolute measurement of the drift velocity and mobility of electrons in high resistivity silicon at room temperature. The electron velocity is obtained from the differential measurement of the drift time of an electron cloud in a silicon drift detector. The main features of the transport scheme of this class of detectors are: the high uniformity of the electron motion, the transport of the signal electrons entirely contained in the high-purity bulk, the low noise timing due to the very small anode capacitance (typical value 100 fF), and the possibility to measure different drift distances, up to the wafer diameter, in the same semiconductor sample. These features make the silicon drift detector an optimal device for high precision measurements of carrier drift properties. The electron drift velocity and mobility in a 10 kΩ cm NTD n-type silicon wafer have been measured as a function of the electric field in the range of possible operation of a typical drift detector (167--633 V/cm). The electron ohmic mobility is found to be 1394 cm 2 /V s. The measurement precision is better than 1%. copyright 1995 American Institute of Physics

  19. Influence of geomagnetic activity and atmospheric pressure in hypertensive adults.

    Science.gov (United States)

    Azcárate, T; Mendoza, B

    2017-09-01

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

  20. Effects of geomagnetic activity on the mesospheric electric fields

    Directory of Open Access Journals (Sweden)

    A. M. Zadorozhny

    Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and ∑Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.

    Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

  1. Effects of geomagnetic activity on the mesospheric electric fields

    Directory of Open Access Journals (Sweden)

    A. M. Zadorozhny

    1998-12-01

    Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and ∑Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

  2. Influence of geomagnetic activity and atmospheric pressure in hypertensive adults

    Science.gov (United States)

    Azcárate, T.; Mendoza, B.

    2017-09-01

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

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

    Science.gov (United States)

    Bailey, Rachel L.; Leonhardt, Roman

    2016-06-01

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

  4. Seepage Model for PA Including Drift Collapse

    International Nuclear Information System (INIS)

    Li, G.; Tsang, C.

    2000-01-01

    The purpose of this Analysis/Model Report (AMR) is to document the predictions and analysis performed using the Seepage Model for Performance Assessment (PA) and the Disturbed Drift Seepage Submodel for both the Topopah Spring middle nonlithophysal and lower lithophysal lithostratigraphic units at Yucca Mountain. These results will be used by PA to develop the probability distribution of water seepage into waste-emplacement drifts at Yucca Mountain, Nevada, as part of the evaluation of the long term performance of the potential repository. This AMR is in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (CRWMS M andO 2000 [153447]). This purpose is accomplished by performing numerical simulations with stochastic representations of hydrological properties, using the Seepage Model for PA, and evaluating the effects of an alternative drift geometry representing a partially collapsed drift using the Disturbed Drift Seepage Submodel. Seepage of water into waste-emplacement drifts is considered one of the principal factors having the greatest impact of long-term safety of the repository system (CRWMS M andO 2000 [153225], Table 4-1). This AMR supports the analysis and simulation that are used by PA to develop the probability distribution of water seepage into drift, and is therefore a model of primary (Level 1) importance (AP-3.15Q, ''Managing Technical Product Inputs''). The intended purpose of the Seepage Model for PA is to support: (1) PA; (2) Abstraction of Drift-Scale Seepage; and (3) Unsaturated Zone (UZ) Flow and Transport Process Model Report (PMR). Seepage into drifts is evaluated by applying numerical models with stochastic representations of hydrological properties and performing flow simulations with multiple realizations of the permeability field around the drift. The Seepage Model for PA uses the distribution of permeabilities derived from air injection testing in niches and in the cross drift to

  5. Autoresonant control of drift waves

    DEFF Research Database (Denmark)

    Shagalov, A.G.; Rasmussen, Jens Juul; Naulin, Volker

    2017-01-01

    The control of nonlinear drift waves in a magnetized plasmas column has been investigated. The studies are based on the Hasegawa–Mima model, which is solved on a disk domain with radial inhomogeneity of the plasma density. The system is forced by a rotating potential with varying frequency defined...... on the boundary. To excite and control the waves we apply the autoresonant effect, taking place when the amplitude of the forcing exceeds a threshold value and the waves are phase-locked with the forcing. We demonstrate that the autoresonant approach is applicable for excitation of a range of steady nonlinear...... waves of the lowest azimuthal mode numbers and for controlling their amplitudes and phases. We also demonstrate the excitation of zonal flows (m = 0 modes), which are controlled via the forced modes....

  6. Single wire drift chamber design

    International Nuclear Information System (INIS)

    Krider, J.

    1987-01-01

    This report summarizes the design and prototype tests of single wire drift chambers to be used in Fermilab test beam lines. The goal is to build simple, reliable detectors which require a minimum of electronics. Spatial resolution should match the 300 μm rms resolution of the 1 mm proportional chambers that they will replace. The detectors will be used in beams with particle rates up to 20 KHz. Single track efficiency should be at least 99%. The first application will be in the MT beamline, which has been designed for calibration of CDF detectors. A set of four x-y modules will be used to track and measure the momentum of beam particles

  7. Drift effects in CANDU reactors

    International Nuclear Information System (INIS)

    Koclas, J.; Roy, R.; Marleau, G.

    1993-01-01

    The diffusion equation is an approximation to the transport equation which relies on the validity of Fick's law. Since this law is not explicitly integrated in the transport equation it can only be derived approximately using homogenization theories. However, such homogenization theories state that when the cell is not symmetric Fick's law breaks down due to the presence of an additional term to the neutron current, called the drift term. In fact, this term can be interpreted as a transport correction to Fick's law which tends to increase the neutron current in a direction opposite to that specified by the flux gradient. In this paper, we investigate how the presence of asymmetric liquid zone controllers will modify the flux distribution inside a CANDU core. 5 refs., 2 figs., 1 tab

  8. A Quaternary Geomagnetic Instability Time Scale

    Science.gov (United States)

    Singer, B. S.

    2013-12-01

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

  9. Historical and Contemporary Trends in the Size, Drift, and Color of Jupiter's Great Red Spot

    Science.gov (United States)

    Simon, Amy A.; Tabataba-Vakili, Fachreddin; Cosentino, Richard; Beebe, Reta F.; Wong, Michael H.; Orton, Glenn S.

    2018-04-01

    Observations of Jupiter’s Great Red Spot (GRS) span more than 150 years. This allows for careful measurements of its size and drift rate. High spatial resolution spacecraft data also allow tracking of its spectral characteristics and internal dynamics and structure. The GRS continues to shrink in longitudinal length at an approximately linear rate of 0.°194 yr‑1 and in latitudinal width at 0.°048 yr‑1. Its westward drift rate (relative to System III W. longitude) has increased from ∼0.°26/day in the 1980s to ∼0.°36/day currently. Since 2014, the GRS’s short wavelength (indicating a change in clouds/haze at high altitudes. In addition, its north–south color asymmetry has decreased, and the dark core has become smaller. Internal velocities have increased on its east and west edges, and decreased on the north and south, resulting in decreased relative vorticity and circulation. The GRS’s color changes from 2014 to 2017 may be explained by changes in stretching vorticity or divergence acting to balance the decrease in relative vorticity.

  10. Energy drift in reversible time integration

    International Nuclear Information System (INIS)

    McLachlan, R I; Perlmutter, M

    2004-01-01

    Energy drift is commonly observed in reversible integrations of systems of molecular dynamics. We show that this drift can be modelled as a diffusion and that the typical energy error after time T is O(√T). (letter to the editor)

  11. TBV 361 RESOLUTION ANALYSIS: EMPLACEMENT DRIFT ORIENTATION

    International Nuclear Information System (INIS)

    Lin, M.; Kicker, D.C.; Sellers, M.D.

    1999-01-01

    The purpose of this To Be Verified/To Be Determined (TBX) resolution analysis is to release ''To Be Verified'' (TBV)-361 related to the emplacement drift orientation. The system design criterion in ''Subsurface Facility System Description Document'' (CRWMS M andO 1998a, p.9) specifies that the emplacement drift orientation relative to the dominant joint orientations should be at least 30 degrees. The specific objectives for this analysis include the following: (1) Collect and evaluate key block data developed for the repository host horizon rock mass. (2) Assess the dominant joint orientations based on available fracture data. (3) Document the maximum block size as a function of drift orientation. (4) Assess the applicability of the drift orientation/joint orientation offset criterion in the ''Subsurface Facility System Description Document'' (CRWMS M andO 1998a, p.9). (5) Consider the effects of seepage on drift orientation. (6) Verify that the viability assessment (VA) drift orientation complies with the drift orientation/joint orientation offset criterion, or provide justifications and make recommendations for modifying the VA emplacement drift layout. In addition to providing direct support to the System Description Document (SDD), the release of TBV-361 will provide support to the Repository Subsurface Design Department. The results from this activity may also provide data and information needs to support the MGR Requirements Department, the MGR Safety Assurance Department, and the Performance Assessment Organization

  12. Silicon drift detectors, present and future prospects

    Science.gov (United States)

    Takahashi, J.; Bellwied, R.; Beuttenmuller, R.; Caines, H.; Chen, W.; Dyke, H.; Hoffmann, G. W.; Humanic, T.; Kotov, I.; Kuczewski, P.; Leonhardt, W.; Li, Z.; Lynn, D.; Minor, R.; Munhoz, M.; Ott, G.; Pandey, S. U.; Schambach, J.; Soja, R.; Sugarbaker, E.; Willson, R. M.

    2001-04-01

    Silicon drift detectors provide unambiguous two-dimensional position information for charged particle detection with a single detector layer. A large area silicon drift detector was developed for the inner tracking detector of the STAR experiment at RHIC. In this paper, we discuss the lessons learned and the future prospects of this technology.

  13. Equatorial electrojet in the Indian region during the geomagnetic ...

    Indian Academy of Sciences (India)

    1998-11-14

    Nov 14, 1998 ... In the recovery phase of the storm, the electric field due to shielding layer penetrates to equatorial latitudes as an overshielding electric field with opposite polarity, westward during day- side and eastward during night side (Kelley et al. 1979). In addition to the prompt penetration elec- tric fields, there are ...

  14. FIELD INVESTIGATION OF THE DRIFT SHADOW

    International Nuclear Information System (INIS)

    G.W. Su; T.J. Kneafsey

    2006-01-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming the existence of the drift shadow have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow--and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content using a gravimetric technique, as well as analyzed for chemistry. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift

  15. Role of drifts in diffusive shock acceleration

    International Nuclear Information System (INIS)

    Decker, R.B.

    1988-01-01

    The role played by shock-associated drifts during the diffusive acceleration of charged particles at collisionless MHD shocks is evaluated. In the rest frame of the shock, the total energy gained by a particle is shown to result from two coupled acceleration mechanisms, the usual first-order Fermi mechanism and the drift mechanism. When averaged over a distribution of particles, the ratio of the drift-associated energy gain to the total energy is found to be independent of the total energy at a given theta1 (the angle between the shock normal and the unperturbed upstream magnetic field) in agreement with theoretical predictions. No evidence is found for drift-associated deceleration, suggesting that drifts always augment acceleration. 35 references

  16. Drift reversal capability in helical systems

    International Nuclear Information System (INIS)

    Yokoyama, M.; Itoh, K.; Okamura, S.

    2002-10-01

    The maximum-J (J is the second adiabatic invariant) capability, i.e., the drift reversal capability, is examined in quasi-axisymmetric (QAS) stellarators and quasi-poloidally symmetric (QPS) stellarators as a possible mechanism for turbulent transport suppression. Due to the existence of non-axisymmetry of the magnetic field strength in QAS configurations, a local maximum of J is created to cause the drift reversal. The increase of magnetic shear in finite beta equilibria also has favorable effect in realizing the drift reversal. The radial variation of the uniform magnetic field component plays a crucial role for the drift reversal in a QPS configuration. Thus, the drift reversal capability and its external controllability are demonstrated for QAS and QPS stellarators, by which the impact of magnetic configuration on turbulent transport can be studied in experiments. (author)

  17. Drift reversal capability in helical systems

    International Nuclear Information System (INIS)

    Yokoyama, M.; Itoh, K.; Okamura, S.; Matsuoka, K.; Nakajima, N.; Itoh, S.-I.; Neilson, G.H.; Zarnstorff, M.C.; Rewoldt, G.

    2003-01-01

    The maximum-J (J is the second adiabatic invariant) capability, i.e., the drift reversal capability, is examined in quasi-axisymmetric (QAS) stellarators and quasi-poloidally symmetric (QPS) stellarators as a possible mechanism for turbulent transport suppression. Due to the existence of non-axisymmetry of the magnetic field strength in QAS configurations, a local maximum of J is created to cause the drift reversal. The increase of magnetic shear in finite beta equilibria also has favorable effect in realizing the drift reversal. The radial variation of the uniform magnetic field component plays a crucial role for the drift reversal in a QPS configuration. Thus, the drift reversal capability and its external controllability are demonstrated for QAS and QPS stellarators, by which the impact of magnetic configuration on turbulent transport can be studied in experiments. (author)

  18. Ground Control for Emplacement Drifts for LA

    International Nuclear Information System (INIS)

    Y. Sun

    2004-01-01

    The purpose of this calculation is to analyze the stability of repository emplacement drifts during the preclosure period, and to provide a final ground support method for emplacement drifts for the License Application (LA). The scope of the work includes determination of input parameter values and loads, selection of appropriate process and methods for the calculation, application of selected methods, such as empirical or analytical, to the calculation, development and execution of numerical models, and evaluation of results. Results from this calculation are limited to use for design of the emplacement drifts and the final ground support system installed in these drifts. The design of non-emplacement openings and their ground support systems is covered in the ''Ground Control for Non-Emplacement Drifts for LA'' (BSC 2004c)

  19. Dissipative drift instability in dusty plasma

    Directory of Open Access Journals (Sweden)

    Nilakshi Das

    2012-03-01

    Full Text Available An investigation has been done on the very low-frequency electrostatic drift waves in a collisional dusty plasma. The dust density gradient is taken perpendicular to the magnetic field B0⃗, which causes the drift wave. In this case, low-frequency drift instabilities can be driven by E1⃗×B0⃗ and diamagnetic drifts, where E1⃗ is the perturbed electric field. Dust charge fluctuation is also taken into consideration for our study. The dust- neutral and ion-neutral collision terms have been included in equations of motion. It is seen that the low-frequency drift instability gets damped in such a system. Both dust charging and collision of plasma particles with the neutrals may be responsible for the damping of the wave. Both analytical and numerical techniques have been used while developing the theory.

  20. Average configuration of the geomagnetic tail

    International Nuclear Information System (INIS)

    Fairfield, D.H.

    1979-01-01

    Over 3000 hours of Imp 6 magnetic field data obtained between 20 and 33 R/sub E/ in the geomagnetic tail have been used in a statistical study of the tail configuration. A distribution of 2.5-min averages of B/sub z/ as a function of position across the tail reveals that more flux crosses the equatorial plane near the dawn and dusk flanks (B-bar/sub z/=3.γ) than near midnight (B-bar/sub z/=1.8γ). The tail field projected in the solar magnetospheric equatorial plane deviates from the x axis due to flaring and solar wind aberration by an angle α=-0.9 Y/sub SM/-2.7, where Y/sub SM/ is in earth radii and α is in degrees. After removing these effects, the B/sub y/ component of the tail field is found to depend on interplanetary sector structure. During an 'away' sector the B/sub y/ component of the tail field is on average 0.5γ greater than that during a 'toward' sector, a result that is true in both tail lobes and is independent of location across the tail. This effect means the average field reversal between northern and southern lobes of the tail is more often 178 0 rather than the 180 0 that is generally supposed

  1. Geomagnetism during solar cycle 23: Characteristics

    Directory of Open Access Journals (Sweden)

    Jean-Louis Zerbo

    2013-05-01

    Full Text Available On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996–2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT and yearly averaged solar wind speed (364 km/s are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s, associated to the highest value of the yearly averaged aa index (37 nT. We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum.

  2. The Complexity of Solar and Geomagnetic Indices

    Science.gov (United States)

    Pesnell, W. Dean

    2017-08-01

    How far in advance can the sunspot number be predicted with any degree of confidence? Solar cycle predictions are needed to plan long-term space missions. Fleets of satellites circle the Earth collecting science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Statistical and timeseries analyses of the sunspot number are often used to predict solar activity. These methods have not been completely successful as the solar dynamo changes over time and one cycle's sunspots are not a faithful predictor of the next cycle's activity. In some ways, using these techniques is similar to asking whether the stock market can be predicted. It has been shown that the Dow Jones Industrial Average (DJIA) can be more accurately predicted during periods when it obeys certain statistical properties than at other times. The Hurst exponent is one such way to partition the data. Another measure of the complexity of a timeseries is the fractal dimension. We can use these measures of complexity to compare the sunspot number with other solar and geomagnetic indices. Our concentration is on how trends are removed by the various techniques, either internally or externally. Comparisons of the statistical properties of the various solar indices may guide us in understanding how the dynamo manifests in the various indices and the Sun.

  3. The Contribution of a Geophysical Data Service: The International Service of Geomagnetic Indices

    Directory of Open Access Journals (Sweden)

    M Menvielle

    2013-01-01

    Full Text Available Geomagnetic indices are basic data in Solar-Terrestrial physics and in operational Space Weather activities. The International Service of Geomagnetic Indices (ISGI is in charge of the derivation and dissemination of the geomagnetic indices that are acknowledged by the International Association of Geomagnetism and Aeronomy (IAGA, an IUGG association. Institutes that are not part of ISGI started early in the Internet age to circulate on-line preliminary values of geomagnetic indices. In the absence of quality stamping, this resulted in a very confusing situation. The ISGI label was found to be the simplest and the safest way to insure quality stamping of circulated geomagnetic indices.

  4. A modeling study of ionospheric F2-region storm effects at low geomagnetic latitudes during 17-22 March 1990

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    2006-05-01

    Full Text Available We have presented a comparison between the modeled NmF2 and hmF2, and NmF2 and hmF2, which were observed in the low-latitude ionosphere simultaneously by the Kokubunji, Yamagawa, Okinawa, Manila, Vanimo, and Darwin ionospheric sounders, by the middle and upper atmosphere (MU radar during 17-22 March 1990, and by the Arecibo radar for the time period of 20-22 March 1990. A comparison between the electron and ion temperatures measured by the MU and Arecibo radars and those produced by the model of the ionosphere and plasmasphere is presented. The empirical zonal electric field, the meridional neutral wind taken from the HWM90 wind model, and the NRLMSISE-00 neutral temperature and densities are corrected so that the model results agree reasonably with the ionospheric sounder observations, and the MU and Arecibo radar data. It is proved that the nighttime weakening of the equatorial zonal electric field (in comparison with that produced by the empirical model of Fejer and Scherliess (1997 or Scherliess and Fejer (1999, in combination with the corrected wind-induced plasma drift along magnetic field lines, provides the development of the nighttime enhancements in NmF2 observed over Manila during 17-22 March 1990. As a result, the new physical mechanism of the nighttime NmF2 enhancement formation close to the geomagnetic equator includes the nighttime weakening of the equatorial zonal electric field and equatorward nighttime plasma drift along magnetic field lines caused by neutral wind in the both geomagnetic hemispheres. It is found that the latitudinal positions of the crests depend on the E×B drift velocity and on the neutral wind velocity. The relative role of the main mechanisms of the equatorial anomaly suppression observed during geomagnetic storms is studied for the first time in terms of storm-time variations of the model crest-to-trough ratios of the equatorial anomaly. During most of the studied time period, a total contribution from

  5. Non-Dipole Features of the Geomagnetic Field May Persist for Millions of Years

    Science.gov (United States)

    Biasi, J.; Kirschvink, J. L.

    2017-12-01

    Here we present paleointensity results from within the South Atlantic Anomaly (SAA), which is a large non-dipole feature of the geomagnetic field. Within the area of the SAA, anomalous declinations, inclinations, and intensities are observed. Our results suggest that the SAA has been present for at least 5 Ma. This is orders-of-magnitude greater than any previous estimate, and suggests that some non-dipole features do not `average out' over geologic time, which is a fundamental assumption in all paleodirectional studies. The SAA has been steadily growing in size since the first magnetic measurements were made in the South Atlantic, and it is widely believed to have appeared 400 years ago. Recent studies from South Africa (Tarduno et al. (2015)) and Tristan da Cunha (Shah et al. (2016)) have suggested that the SAA has persisted for 1 ka and 96 ka respectively. We conducted paleointensity (PI) experiments on basaltic lavas from James Ross Island, on the Antarctic Peninsula. This large shield volcano has been erupting regularly over the last 6+ Ma (dated via Ar/Ar geochronology), and therefore contains the most complete volcanostratigraphic record in the south Atlantic. Our PI experiments used the Thellier-Thellier method, the IZZI protocol, and the same selection criteria as the Lawrence et al. (2009) study of Ross Island lavas (near McMurdo Station), which is the only comparable PI study on the Antarctic continent. We determined an average paleointensity at JRI of 13.8±5.2 μT, which is far lower than what we would expect from a dipole field (55 μT). In addition, this is far lower than the current value over James Ross Island of 36 μT. These results support the following conclusions: The time-averaged field model of Juarez et al. (1998) and Tauxe et al. (2013) is strongly favored by our PI data. The SAA has persisted over James Ross Island for at least 5 Ma, and has not drifted significantly over that time. The strength of non-dipole features such as the SAA

  6. Drift velocity and pressure monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2011-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers. The differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest drift velocity monitoring results are discussed.

  7. Drift velocity and pressure monitoring of the CMS muon drift chambers

    CERN Document Server

    Sonnenschein, Lars

    2010-01-01

    The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers because the drift velocity depends on it. Furthermore the differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest pressure monitoring results are discussed.

  8. Transitional geomagnetic impulse hypothesis: Geomagnetic fact or rock-magnetic artifact?

    Science.gov (United States)

    Camps, Pierre; Coe, Robert S.; PréVot, Michel

    1999-08-01

    A striking feature of the Steens Mountain (Oregon) geomagnetic polarity reversal is the two (maybe three) extremely rapid field directional changes (6 degrees per day) proposed to account for unusual behavior in direction of remanent magnetization in a single lava flow. Each of these very fast field changes, or impulses, is associated with a large directional gap (some 90°) in the record. In order to check the spatial reproducibility of the paleomagnetic signal over distances up to several kilometers, we have carried out a paleomagnetic investigation of two new sections (B and F) in the Steens summit region which cover the second and the third directional gap. The main result is the description of two new directions, which are located between the pre second and post second impulse directions. These findings weigh against the hypothesis that the geomagnetic field cause the unusual intraflow fluctuations, which now appears to be more ad hoc as an explanation of the paleomagnetic data. However, the alternative baking hypothesis remains also ad hoc since we have to assume variable rock magnetic properties that we have not yet been able to detect within the flows at the original section Steens A and D 1.5 km to the north. In addition, new results for 22 transitional and normal lava flows in section B are presented that correlate well with earlier results from section A.

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

    Directory of Open Access Journals (Sweden)

    S. Lepidi

    2017-01-01

    Full Text Available 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.

  10. Field investigation of the drift shadow

    International Nuclear Information System (INIS)

    Su, Grace W.; Kneafsey, Timothy J.; Ghezzehei, Teamrat A.; Marshall, Brian D.; Cook, Paul J.

    2005-01-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming its existence have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow and the corresponding hydrological process at the Hazel-Atlas silica-sandmine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine Formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rockmass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content and chemical constituents. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift. Tensiometers, electrical resistance probes, neutron probes, and ground

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

    Science.gov (United States)

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

    2011-10-01

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

  12. Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

    Science.gov (United States)

    Moro, J.; Resende, L. C. A.; Denardini, C. M.; Xu, J.; Batista, I. S.; Andrioli, V. F.; Carrasco, A. J.; Batista, P. P.; Schuch, N. J.

    2017-12-01

    Equatorial E region electric fields (EEFs) inferred from coherent radar data, sporadic-E (Es) layers observed from a digital ionosonde data, and modeling results are used to study the responses of the equatorial E region over São Luís (SLZ, 2.3°S, 44.2°W, -7° dip angle), Brazil, during the super storm of November 2004. The EEF is presented in terms of the zonal (Ey) and vertical (Ez) components in order to analyze the corresponding characteristics of different types of Es seen in ionograms and simulated with the E region ionospheric model. We bring out the variabilities of Ey and Ez components with storm time changes in the equatorial E region. In addition, some aspects of the electric fields and Es behavior in three cases of weak, very weak, and strong Type II occurrences during the recovery phase of the geomagnetic storm are discussed. The connection between the enhanced occurrence and suppressions of the Type II irregularities and the q-type Es (Esq) controlled by electric fields, with the development or disruption of the blanketing sporadic E (Esb) layers produced by wind shear mechanism, is also presented. The mutual presence of Esq along with the Esb occurrences is a clear indicator of the secular drift of the magnetic equator and hence that of the equatorial electrojet (EEJ) over SLZ. The results show evidence about the EEJ and Es layer electrodynamics and coupling during geomagnetic disturbance time electric fields.

  13. Drift-modeling and monitoring comparisons

    International Nuclear Information System (INIS)

    Chen, N.C.J.; Hanna, S.R.

    1977-01-01

    Congress is looking into the conglomeration of nuclear reactors into energy centers of limited area. Drift from cooling towers can corrode and damage structures in the immediate vicinity of the towers, cause a public nuisance if located near parking lots or high-density traffic areas, and endanger local vegetation. The estimation of salt deposition has relied primarily on predictions from a variety of models, with very few direct measurements. One of the major efforts in our program is to evaluate the assumptions, limitations, and applicabilities of various analytical models for drift deposition prediction. Several drift deposition models are compared using a set of standard input conditions. The predicted maximum drift deposition differs by two orders of magnitude, and the downwind locations of the maximum differ by one order of magnitude. The discrepancies are attributed mainly to different assumptions in the models regarding the initial effective height of the droplets. Current programs in which drift characteristics at the tower mouth and drift deposition downwind of the tower are being measured are summarized. At the present time, drift deposition measurements, sufficiently comprehensive for model verifications, are unavailable. Hopefully, the Chalk Point Program will satisfy this need

  14. Seepage into drifts with mechanical degradation

    International Nuclear Information System (INIS)

    Li, Guomin; Tsang, Chin-Fu

    2002-01-01

    Seepage into drifts in unsaturated tuff is an important issue for the long-term performance of the potential nuclear waste repository at Yucca Mountain, Nevada. Drifts in which waste packages will potentially be emplaced are subject to degradation in the form of rockfall from the drift ceiling induced by stress relief, seismic, or thermal effects. The objective of this study is to calculate seepage rates for various drift-degradation scenarios and for different values of percolation flux for the Topopah Spring middle nonlithophysal (Tptpmn) and the Topopah Spring lower lithophysal (Tptpll) units. Seepage calculations are conducted by (1) defining a heterogeneous permeability model on the drift scale that is consistent with field data, (2) selecting calibrated parameters associated with the Tptpmn and Tptpll units, and (3) simulating seepage on detailed degraded-drift profiles, which were obtained from a separate rock mechanics engineering analysis. The simulation results indicate (1) that the seepage threshold (i.e., the percolation flux at which seepage first occurs) is not significantly changed by drift degradation, and (2) the degradation-induced increase in seepage above the threshold is influenced more by the shape of the cavity created by rockfall than the rockfall volume

  15. Intermittency and multifractional Brownian character of geomagnetic time series

    Directory of Open Access Journals (Sweden)

    G. Consolini

    2013-07-01

    Full Text Available The Earth's magnetosphere exhibits a complex behavior in response to the solar wind conditions. This behavior, which is described in terms of mutifractional Brownian motions, could be the consequence of the occurrence of dynamical phase transitions. On the other hand, it has been shown that the dynamics of the geomagnetic signals is also characterized by intermittency at the smallest temporal scales. Here, we focus on the existence of a possible relationship in the geomagnetic time series between the multifractional Brownian motion character and the occurrence of intermittency. In detail, we investigate the multifractional nature of two long time series of the horizontal intensity of the Earth's magnetic field as measured at L'Aquila Geomagnetic Observatory during two years (2001 and 2008, which correspond to different conditions of solar activity. We propose a possible double origin of the intermittent character of the small-scale magnetic field fluctuations, which is related to both the multifractional nature of the geomagnetic field and the intermittent character of the disturbance level. Our results suggest a more complex nature of the geomagnetic response to solar wind changes than previously thought.

  16. Improving geomagnetic observatory data in the South Atlantic Anomaly

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

    Mikhailov, A. V.

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

  18. Green corona, geomagnetic activity and radar meteor rates

    International Nuclear Information System (INIS)

    Prikryl, P.

    1979-01-01

    The short-term dependence of radar meteor rates on geomagnetic activity and/or central meridian passage (CMP) of bright or faint green corona regions is studied. A superimposed-epoch analysis was applied to radar meteor observations from the Ottawa patrol radar (Springhill, Ont.) and Ksub(p)-indices of geomagnetic activity for the period 1963 to 1967. During the minimum of solar activity (1963 to 1965) the CMP of bright coronal regions was followed by the maximum in the daily rates of persistent meteor echoes (>=4s), and the minimum in the daily sums of Ksub(p)-indices whereas the minimum or the maximum, respectively, occurs after the CMP of faint coronal regions. The time delay between the CMP of coronal structures and the corresponding maxima or minima is found to be 3 to 4 days. However, for the period immediately after the minimum of solar activity (1966 to 1967) the above correlation with the green corona is void both for the geomagnetic activity and radar meteor rates. An inverse correlation was found between the radar meteor rates and the geomagnetic activity irrespective of the solar activity. The observed effect can be ascribed to the solar-wind-induced ''geomagnetic'' heating of the upper atmosphere and to the subsequent change in the density gradient in the meteor zone. (author)

  19. Chandler wobbles and the geomagnetic field

    Science.gov (United States)

    Flodmark, Stig; Davstad, K.

    1986-11-01

    Paleomagnetic motion of the magnetic pole is explained by angular momentum balance between the magnetic field, inner core, outer core, and mantle. The Chandler wobbles are explained as a nutation of the mantle and crust, caused by transfer of angular momentum between the core and mantle. Evidence is found for the atmosphere not to be fully responsible for the annual oscillation period of the Chandler wobbles. The main reasons for the principal periods of 12 and 14 months are found to be the flattenings of mantle and core, respectively. The fluid core rotates collectively, as a consequence of globally coworking long-distance electromagnetic coupling. Short-distance forces may locally displace fluid core material without essentially deforming its ellipsoid of inertia. The longitudinal polar drifts of the mantle and outer core are also explained by core-mantle interaction. The core is found to force the Chandler period on the mantle, and it has high wobbling energy in comparison with the mantle.

  20. Nonlinear Gyrokinetic Theory With Polarization Drift

    International Nuclear Information System (INIS)

    Wang, L.; Hahm, T.S.

    2010-01-01

    A set of the electrostatic toroidal gyrokinetic Vlasov equation and the Poisson equation, which explicitly includes the polarization drift, is derived systematically by using Lie-transform method. The polarization drift is introduced in the gyrocenter equations of motion, and the corresponding polarization density is derived. Contrary to the wide-spread expectation, the inclusion of the polarization drift in the gyrocenter equations of motion does not affect the expression for the polarization density significantly. This is due to modification of the gyrocenter phase-space volume caused by the electrostatic potential [T. S. Hahm, Phys. Plasmas 3, 4658 (1996)].

  1. Pixelated CdZnTe drift detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2005-01-01

    A technique, the so-called Drift Strip Method (DSM), for improving the CdZnTe detector energy response to hard X-rays and gamma-rays was applied as a pixel geometry. First tests have confirmed that this detector type provides excellent energy resolution and imaging performance. We specifically...... report on the performance of 3 mm thick prototype CZT drift pixel detectors fabricated using material from eV-products. We discuss issues associated with detector module performance. Characterization results obtained from several prototype drift pixel detectors are presented. Results of position...

  2. Computer controlled drifting of Si(Li) detectors

    International Nuclear Information System (INIS)

    Landis, D.A.; Wong, Y.K.; Walton, J.T.; Goulding, F.S.

    1989-01-01

    A relatively inexpensive computer-controlled system for performing the drift process used in fabricating Si(Li) detectors is described. The system employs a small computer to monitor the leakage current, applied voltage and temperature on eight individual drift stations. The associated computer program initializes the drift process, monitors the drift progress and then terminates the drift when an operator set drift time has elapsed. The improved control of the drift with this system has been well demonstrated over the past three years in the fabrication of a variety of Si(Li) detectors. A few representative system responses to detector behavior during the drift process are described

  3. Dynamical similarity of geomagnetic field reversals.

    Science.gov (United States)

    Valet, Jean-Pierre; Fournier, Alexandre; Courtillot, Vincent; Herrero-Bervera, Emilio

    2012-10-04

    No consensus has been reached so far on the properties of the geomagnetic field during reversals or on the main features that might reveal its dynamics. A main characteristic of the reversing field is a large decrease in the axial dipole and the dominant role of non-dipole components. Other features strongly depend on whether they are derived from sedimentary or volcanic records. Only thermal remanent magnetization of lava flows can capture faithful records of a rapidly varying non-dipole field, but, because of episodic volcanic activity, sequences of overlying flows yield incomplete records. Here we show that the ten most detailed volcanic records of reversals can be matched in a very satisfactory way, under the assumption of a common duration, revealing common dynamical characteristics. We infer that the reversal process has remained unchanged, with the same time constants and durations, at least since 180 million years ago. We propose that the reversing field is characterized by three successive phases: a precursory event, a 180° polarity switch and a rebound. The first and third phases reflect the emergence of the non-dipole field with large-amplitude secular variation. They are rarely both recorded at the same site owing to the rapidly changing field geometry and last for less than 2,500 years. The actual transit between the two polarities does not last longer than 1,000 years and might therefore result from mechanisms other than those governing normal secular variation. Such changes are too brief to be accurately recorded by most sediments.

  4. A superposed epoch analysis of geomagnetic storms

    Directory of Open Access Journals (Sweden)

    J. R. Taylor

    1994-06-01

    Full Text Available A superposed epoch analysis of geomagnetic storms has been undertaken. The storms are categorised via their intensity (as defined by the Dst index. Storms have also been classified here as either storm sudden commencements (SSCs or storm gradual commencements (SGCs, that is all storms which did not begin with a sudden commencement. The prevailing solar wind conditions defined by the parameters solar wind speed (vsw, density (ρsw and pressure (Psw and the total field and the components of the interplanetary magnetic field (IMF during the storms in each category have been investigated by a superposed epoch analysis. The southward component of the IMF, appears to be the controlling parameter for the generation of small SGCs (-100 nT< minimum Dst ≤ -50 nT for ≥ 4 h, but for SSCs of the same intensity solar wind pressure is dominant. However, for large SSCs (minimum Dst ≤ -100 nT for ≥ 4 h the solar wind speed is the controlling parameter. It is also demonstrated that for larger storms magnetic activity is not solely driven by the accumulation of substorm activity, but substantial energy is directly input via the dayside. Furthermore, there is evidence that SSCs are caused by the passage of a coronal mass ejection, whereas SGCs result from the passage of a high speed/ slow speed coronal stream interface. Storms are also grouped by the sign of Bz during the first hour epoch after the onset. The sign of Bz at t = +1 h is the dominant sign of the Bz for ~24 h before the onset. The total energy released during storms for which Bz was initially positive is, however, of the same order as for storms where Bz was initially negative.

  5. Fluxgate Magnetometer Array for Geomagnetic Abnormal Phenomena Tracking

    Directory of Open Access Journals (Sweden)

    Xiaomei Wang

    2011-06-01

    Full Text Available The objective of this project is to develop a flexible observation mode for a geomagnetic abnormal phenomena tracking system. The instrument, based on ring core fluxgate magnetometer technology, improves the field environment performance. Using wireless technology provides on-the-spot mobile networking for the observational data, with efficient access to the earthquake precursor observation network. It provides a powerful detection method for earthquake short-term prediction through installation of a low-noise fluxgate magnetometer array, intensely observing the phenomenon of geomagnetic disturbances and abnormal low-frequency electromagnetic signals in different latitudes, then carrying out observational data processing and exploring the relationship between earthquake activity and geomagnetic field changes.

  6. Operations of the World Data Centre for Geomagnetism, Edinburgh

    Directory of Open Access Journals (Sweden)

    S J Reay

    2013-01-01

    Full Text Available The British Geological Survey has operated a World Data Centre for Geomagnetism since 1966. Geomagnetic time-series data from around 280 observatories worldwide at a number of time resolutions are held along with various magnetic survey, model, and activity index data. The operation of this data centre provides a valuable resource for the geomagnetic research community. The operation of the WDC and details of the range of data held are presented. The quality control procedures that are applied to incoming data are described as is the work to collaborate with other data centres to distribute and improve the overall consistency of data held worldwide. The development of standards for metadata associated with datasets is demonstrated, and current efforts to digitally preserve the BGS analogue holdings of magnetograms and observatory yearbooks are described.

  7. Midlatitude cooling caused by geomagnetic field minimum during polarity reversal.

    Science.gov (United States)

    Kitaba, Ikuko; Hyodo, Masayuki; Katoh, Shigehiro; Dettman, David L; Sato, Hiroshi

    2013-01-22

    The climatic effects of cloud formation induced by galactic cosmic rays (CRs) has recently become a topic of much discussion. The CR-cloud connection suggests that variations in geomagnetic field intensity could change climate through modulation of CR flux. This hypothesis, however, is not well-tested using robust geological evidence. Here we present paleoclimate and paleoenvironment records of five interglacial periods that include two geomagnetic polarity reversals. Marine oxygen isotope stages 19 and 31 contain both anomalous cooling intervals during the sea-level highstands and the Matuyama-Brunhes and Lower Jaramillo reversals, respectively. This contrasts strongly with the typical interglacial climate that has the temperature maximum at the sea-level peak. The cooling occurred when the field intensity dropped to 40% increase in CR flux. The climate warmed rapidly when field intensity recovered. We suggest that geomagnetic field intensity can influence global climate through the modulation of CR flux.

  8. Anomalous changes of vertical geomagnetic field in Kamchatka

    Directory of Open Access Journals (Sweden)

    Moroz Yuriy

    2016-01-01

    Full Text Available Secular variations of the vertical geomagnetic field at Paratunka (Kamchatka, Kakioka (Honshu, Mamambetsu (Hokkaido and Patrony (Irkutsk are considered from 1968 to 2014. Comparative analysis of secular variations showed that from 1968 to 2001, similar variations with the intensity of first hundreds on nT are obvious at four observatories. For the following period from 2001 to 2014, the secular variation at Paratunka observatory differs from other observatories. This disagreement of the secular geomagnetic variation at Paratunka observatory is timed to the increase of seismicity at the depth of 400-700 km in South Kamchatka region. It is suggested that in the result of increase of the seismicity in the region of transition from the upper to lower mantle, physical and chemical processes became more active. That caused formation of a large geo-electrical inhomogeneity which affected the behavior of the vertical component of geomagnetic field.

  9. Unintended Positional Drift and Its Potential Solutions

    DEFF Research Database (Denmark)

    Nilsson, Niels Christian; Serafin, Stefania; Nordahl, Rolf

    2013-01-01

    many users unintentionally move forward while walking in place. We refer to this phenomenon accidental movement as Unintended Positional Drift. The poster presents evidence of the phenomenon's existence and subsequently discusses different design solutions which potentially could circumvent the problem....

  10. CROSS DRIFT ALCOVE/NICHE UTILITIES ANALYSIS

    International Nuclear Information System (INIS)

    S. Goodin

    1999-01-01

    The purpose of this analysis is to provide the design basis and general arrangement requirements of the non-potable water, waste water, compressed air and ventilation (post excavation) utilities required in support of the Cross Drift alcoves and niches

  11. Travelling fronts in stochastic Stokes’ drifts

    KAUST Repository

    Blanchet, Adrien; Dolbeault, Jean; Kowalczyk, Michał

    2008-01-01

    By analytical methods we study the large time properties of the solution of a simple one-dimensional model of stochastic Stokes' drift. Semi-explicit formulae allow us to characterize the behaviour of the solutions and compute global quantities

  12. Self-shielding flex-circuit drift tube, drift tube assembly and method of making

    Science.gov (United States)

    Jones, David Alexander

    2016-04-26

    The present disclosure is directed to an ion mobility drift tube fabricated using flex-circuit technology in which every other drift electrode is on a different layer of the flex-circuit and each drift electrode partially overlaps the adjacent electrodes on the other layer. This results in a self-shielding effect where the drift electrodes themselves shield the interior of the drift tube from unwanted electro-magnetic noise. In addition, this drift tube can be manufactured with an integral flex-heater for temperature control. This design will significantly improve the noise immunity, size, weight, and power requirements of hand-held ion mobility systems such as those used for explosive detection.

  13. Strange Attractors in Drift Wave Turbulence

    International Nuclear Information System (INIS)

    Lewandowski, J.L.V.

    2003-01-01

    A multi-grid part-in-cell algorithm for a shearless slab drift wave model with kinetic electrons is presented. The algorithm, which is based on an exact separation of adiabatic and nonadiabatic electron responses, is used to investigate the presence of strange attractors in drift wave turbulence. Although the simulation model has a large number of degrees of freedom, it is found that the strange attractor is low-dimensional and that it is strongly affected by dissipative (collisional) effects

  14. SEEPAGE MODEL FOR PA INCLUDING DRIFT COLLAPSE

    International Nuclear Information System (INIS)

    C. Tsang

    2004-01-01

    The purpose of this report is to document the predictions and analyses performed using the seepage model for performance assessment (SMPA) for both the Topopah Spring middle nonlithophysal (Tptpmn) and lower lithophysal (Tptpll) lithostratigraphic units at Yucca Mountain, Nevada. Look-up tables of seepage flow rates into a drift (and their uncertainty) are generated by performing numerical simulations with the seepage model for many combinations of the three most important seepage-relevant parameters: the fracture permeability, the capillary-strength parameter 1/a, and the percolation flux. The percolation flux values chosen take into account flow focusing effects, which are evaluated based on a flow-focusing model. Moreover, multiple realizations of the underlying stochastic permeability field are conducted. Selected sensitivity studies are performed, including the effects of an alternative drift geometry representing a partially collapsed drift from an independent drift-degradation analysis (BSC 2004 [DIRS 166107]). The intended purpose of the seepage model is to provide results of drift-scale seepage rates under a series of parameters and scenarios in support of the Total System Performance Assessment for License Application (TSPA-LA). The SMPA is intended for the evaluation of drift-scale seepage rates under the full range of parameter values for three parameters found to be key (fracture permeability, the van Genuchten 1/a parameter, and percolation flux) and drift degradation shape scenarios in support of the TSPA-LA during the period of compliance for postclosure performance [Technical Work Plan for: Performance Assessment Unsaturated Zone (BSC 2002 [DIRS 160819], Section I-4-2-1)]. The flow-focusing model in the Topopah Spring welded (TSw) unit is intended to provide an estimate of flow focusing factors (FFFs) that (1) bridge the gap between the mountain-scale and drift-scale models, and (2) account for variability in local percolation flux due to

  15. Ponderomotive modification of drift tearing modes

    International Nuclear Information System (INIS)

    Urquijo, G.; Singh, R.; Sen, A.

    1997-01-01

    The linear characteristics of drift tearing modes are investigated in the presence of a significant background of radio-frequency (RF) waves in the ion cyclotron range of frequencies. The ponderomotive force, arising from the radial gradients in the RF field energy, is found to significantly modify the inner layer solutions of the drift tearing modes. It can have a stabilizing influence, even at moderate RF powers, provided the field energy has a decreasing radial profile at the mode rational surface. (author)

  16. Unstable universal drift eigenmodes in toroidal plasmas

    International Nuclear Information System (INIS)

    Cheng, C.Z.; Chen, L.

    1980-01-01

    The eigenmode equation describing ballooning collisionless drift instabilities is analyzed both analytically and numerically. A new branch of eigenmodes, which corresponds to quasi-bound states due to toroidal coupling effects such as ion delB drifts, is shown to be destabilized by electron Landau damping for typical tokamak parameters. This branch cannot be understood by the strong coupling approximation. However, the slab-like (Pearlstein--Berk-type) branch is found to remain stable and experience enhanced shear damping

  17. Effects of Fault Displacement on Emplacement Drifts

    International Nuclear Information System (INIS)

    Duan, F.

    2000-01-01

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10 -5 adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M and O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure

  18. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  19. Turbulent Diffusion of the Geomagnetic Field and Dynamo Theories

    OpenAIRE

    Filippi, Enrico

    2016-01-01

    The thesis deals with the Dynamo Theories of the Earth’s Magnetic Field and mainly deepens the turbulence phenomena in the fluid Earth’s core. Indeed, we think that these phenomena are very important to understand the recent decay of the geomagnetic field. The thesis concerns also the dynamics of the outer core and some very rapid changes of the geomagnetic field observed in the Earth’s surface and some aspects regarding the (likely) isotropic turbulence in the Magnetohydrodynamics. These top...

  20. Evaluation of candidate geomagnetic field models for IGRF-12

    DEFF Research Database (Denmark)

    Thébault, Erwan; Finlay, Chris; Alken, Patrick

    2015-01-01

    Background: The 12th revision of the International Geomagnetic Reference Field (IGRF) was issued in December 2014 by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html). This revision comprises new spherical...... by the British Geological Survey (UK), DTU Space (Denmark), ISTerre (France), IZMIRAN (Russia), NOAA/NGDC (USA), GFZ Potsdam (Germany), NASA/GSFC (USA), IPGP (France), LPG Nantes (France), and ETH Zurich (Switzerland). Each candidate model was carefully evaluated and compared to all other models and a mean model...

  1. IMF sector behavior estimated from geomagnetic data at South Pole

    International Nuclear Information System (INIS)

    Matsushita, S.; Xu, W.h.

    1981-01-01

    IMF sector behavior which has previously been estimated from the geomagnetic data at Godhavn is confirmed by study of the data at South Pole for 1959--1970 with the same estimation technique, taking the difference between northern and southern hemispheres into consideration. A method to improve (about 18%) the agreement between assigned and actual sector structures by study of the data at the two stations is suggested. Geomagnetic disturbance effects on sector estimation are discussed, and reversed sector effects in winter are given special emphasis

  2. Evaluation of candidate geomagnetic field models for IGRF-12

    OpenAIRE

    Erwan Thébault; Christopher C. Finlay; Patrick Alken; Ciaran D. Beggan; Elisabeth Canet; Arnaud Chulliat; Benoit Langlais; V. Lesur; Frank J. Lowes; Chandrasekharan Manoj; Martin Rother; Reyko Schachtschneider

    2015-01-01

    Background: The 12th revision of the International Geomagnetic Reference Field (IGRF) was issued in December 2014 by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html). This revision comprises new spherical harmonic main field models for epochs 2010.0 (DGRF-2010) and 2015.0 (IGRF-2015) and predictive linear secular variation for the interval 2015.0-2020.0 (SV-2010-2015). Findings: The models were deri...

  3. International Geomagnetic Reference Field: the 12th generation

    OpenAIRE

    Thébault , Erwan; Finlay , Christopher ,; Beggan , Ciarán ,; Alken , Patrick; Aubert , Julien ,; Barrois , Olivier; Bertrand , François; Bondar , Tatiana; Boness , Axel; Brocco , Laura; Canet , Elisabeth ,; Chambodut , Aude; Chulliat , Arnaud ,; Coïsson , Pierdavide ,; Civet , François

    2015-01-01

    International audience; The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, p...

  4. Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Adler, V; Beauceron, S; Blyweert, S; D'Hondt, J; De Weirdt, S; Devroede, O; Heyninck, J; Kalogeropoulos, A; Maes, J; Maes, M; Mozer, M U; Tavernier, S; Van Doninck, W; Van Mulders, P; Villella, I; Bouhali, O; Chabert, E C; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Elgammal, S; Gay, A P R; Hammad, G H; Marage, P E; Rugovac, S; Vander Velde, C; Vanlaer, P; Wickens, J; Grunewald, M; Klein, B; Marinov, A; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Basegmez, S; Bruno, G; Caudron, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Lemaitre, V; Militaru, O; Ovyn, S; Piotrzkowski, K; Quertenmont, L; Schul, N; Beliy, N; Daubie, E; Alves, G A; Pol, M E; Souza, M H G; Carvalho, W; De Jesus Damiao, D; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Oguri, V; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Fernandez Perez Tomei, T R; Ferreira Dias, M A; Gregores, E M; Novaes, S F; Abadjiev, K; Anguelov, T; Damgov, J; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Stoykova, S; Sultanov, G; Trayanov, R; Vankov, I; Dimitrov, A; Dyulendarova, M; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Toteva, Z; Chen, G M; Chen, H S; Guan, W; Jiang, C H; Liang, D; Liu, B; Meng, X; Tao, J; Wang, J; Wang, Z; Xue, Z; Zhang, Z; Ban, Y; Cai, J; Ge, Y; Guo, S; Hu, Z; Mao, Y; Qian, S J; Teng, H; Zhu, B; Avila, C; Baquero Ruiz, M; Carrillo Montoya, C A; Gomez, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Reyes Romero, D; Sanabria, J C; Godinovic, N; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Fereos, R; Galanti, M; Mousa, J; Papadakis, A; Ptochos, F; Razis, P A; Tsiakkouri, D; Zinonos, Z; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Anttila, E; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Nysten, J; Tuominen, E; Tuominiemi, J; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Nedelec, P; Sillou, D; Besancon, M; Chipaux, R; Dejardin, M; Denegri, D; Descamps, J; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Lemaire, M C; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Rousseau, D; Titov, M; Verrecchia, P; Baffioni, S; Bianchini, L; Bluj, M; Busson, P; Charlot, C; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Paganini, P; Sirois, Y; Thiebaux, C; Zabi, A; Agram, J L; Besson, A; Bloch, D; Bodin, D; Brom, J M; Conte, E; Drouhin, F; Fontaine, J C; Gelé, D; Goerlach, U; Gross, L; Juillot, P; Le Bihan, A C; Patois, Y; Speck, J; Van Hove, P; Baty, C; Bedjidian, M; Blaha, J; Boudoul, G; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; Dupasquier, T; El Mamouni, H; Fassi, F; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Lumb, N; Mirabito, L; Perries, S; Vander Donckt, M; Verdier, P; Djaoshvili, N; Roinishvili, N; Roinishvili, V; Amaglobeli, N; Adolphi, R; Anagnostou, G; Brauer, R; Braunschweig, W; Edelhoff, M; Esser, H; Feld, L; Karpinski, W; Khomich, A; Klein, K; Mohr, N; Ostaptchouk, A; Pandoulas, D; Pierschel, G; Raupach, F; Schael, S; Schultz von Dratzig, A; Schwering, G; Sprenger, D; Thomas, M; Weber, M; Wittmer, B; Wlochal, M; Actis, O; Altenhöfer, G; Bender, W; Biallass, P; Erdmann, M; Fetchenhauer, G; Frangenheim, J; Hebbeker, T; Hilgers, G; Hinzmann, A; Hoepfner, K; Hof, C; Kirsch, M; Klimkovich, T; Kreuzer, P; Lanske, D; Merschmeyer, M; Meyer, A; Philipps, B; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Sowa, M; Steggemann, J; Szczesny, H; Teyssier, D; Zeidler, C; Bontenackels, M; Davids, M; Duda, M; Flügge, G; Geenen, H; Giffels, M; Haj Ahmad, W; Hermanns, T; Heydhausen, D; Kalinin, S; Kress, T; Linn, A; Nowack, A; Perchalla, L; Poettgens, M; Pooth, O; Sauerland, P; Stahl, A; Tornier, D; Zoeller, M H; Aldaya Martin, M; Behrens, U; Borras, K; Campbell, A; Castro, E; Dammann, D; Eckerlin, G; Flossdorf, A; Flucke, G; Geiser, A; Hatton, D; Hauk, J; Jung, H; Kasemann, M; Katkov, I; Kleinwort, C; Kluge, H; Knutsson, A; Kuznetsova, E; Lange, W; Lohmann, W; Mankel, R; Marienfeld, M; Meyer, A B; Miglioranzi, S; Mnich, J; Ohlerich, M; Olzem, J; Parenti, A; Rosemann, C; Schmidt, R; Schoerner-Sadenius, T; Volyanskyy, D; Wissing, C; Zeuner, W D; Autermann, C; Bechtel, F; Draeger, J; Eckstein, D; Gebbert, U; Kaschube, K; Kaussen, G; Klanner, R; Mura, B; Naumann-Emme, S; Nowak, F; Pein, U; Sander, C; Schleper, P; Schum, T; Stadie, H; Steinbrück, G; Thomsen, J; Wolf, R; Bauer, J; Blüm, P; Buege, V; Cakir, A; Chwalek, T; De Boer, W; Dierlamm, A; Dirkes, G; Feindt, M; Felzmann, U; Frey, M; Furgeri, A; Gruschke, J; Hackstein, C; Hartmann, F; Heier, S; Heinrich, M; Held, H; Hirschbuehl, D; Hoffmann, K H; Honc, S; Jung, C; Kuhr, T; Liamsuwan, T; Martschei, D; Mueller, S; Müller, Th; Neuland, M B; Niegel, M; Oberst, O; Oehler, A; Ott, J; Peiffer, T; Piparo, D; Quast, G; Rabbertz, K; Ratnikov, F; Ratnikova, N; Renz, M; Saout, C; Sartisohn, G; Scheurer, A; Schieferdecker, P; Schilling, F P; Schott, G; Simonis, H J; Stober, F M; Sturm, P; Troendle, D; Trunov, A; Wagner, W; Wagner-Kuhr, J; Zeise, M; Zhukov, V; Ziebarth, E B; Daskalakis, G; Geralis, T; Karafasoulis, K; Kyriakis, A; Loukas, D; Markou, A; Markou, C; Mavrommatis, C; Petrakou, E; Zachariadou, A; Gouskos, L; Katsas, P; Panagiotou, A; Evangelou, I; Kokkas, P; Manthos, N; Papadopoulos, I; Patras, V; Triantis, F A; Bencze, G; Boldizsar, L; Debreczeni, G; Hajdu, C; Hernath, S; Hidas, P; Horvath, D; Krajczar, K; Laszlo, A; Patay, G; Sikler, F; Toth, N; Vesztergombi, G; Beni, N; Christian, G; Imrek, J; Molnar, J; Novak, D; Palinkas, J; Szekely, G; Szillasi, Z; Tokesi, K; Veszpremi, V; Kapusi, A; Marian, G; Raics, P; Szabo, Z; Trocsanyi, Z L; Ujvari, B; Zilizi, G; Bansal, S; Bawa, H S; Beri, S B; Bhatnagar, V; Jindal, M; Kaur, M; Kaur, R; Kohli, J M; Mehta, M Z; Nishu, N; Saini, L K; Sharma, A; Singh, A; Singh, J B; Singh, S P; Ahuja, S; Arora, S; Bhattacharya, S; Chauhan, S; Choudhary, B C; Gupta, P; Jain, S; Jha, M; Kumar, A; Ranjan, K; Shivpuri, R K; Srivastava, A K; Choudhury, R K; Dutta, D; Kailas, S; Kataria, S K; Mohanty, A K; Pant, L M; Shukla, P; Topkar, A; Aziz, T; Guchait, M; Gurtu, A; Maity, M; Majumder, D; Majumder, G; Mazumdar, K; Nayak, A; Saha, A; Sudhakar, K; Banerjee, S; Dugad, S; Mondal, N K; Arfaei, H; Bakhshiansohi, H; Fahim, A; Jafari, A; Mohammadi Najafabadi, M; Moshaii, A; Paktinat Mehdiabadi, S; Rouhani, S; Safarzadeh, B; Zeinali, M; Felcini, M; Abbrescia, M; Barbone, L; Chiumarulo, F; Clemente, A; Colaleo, A; Creanza, D; Cuscela, G; De Filippis, N; De Palma, M; De Robertis, G; Donvito, G; Fedele, F; Fiore, L; Franco, M; Iaselli, G; Lacalamita, N; Loddo, F; Lusito, L; Maggi, G; Maggi, M; Manna, N; Marangelli, B; My, S; Natali, S; Nuzzo, S; Papagni, G; Piccolomo, S; Pierro, G A; Pinto, C; 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Dykstra, D; Eartly, D P; Elias, J E; Elvira, V D; Evans, D; Feng, L; Fischler, M; Fisk, I; Foulkes, S; Freeman, J; Gartung, P; Gottschalk, E; Grassi, T; Green, D; Guo, Y; Gutsche, O; Hahn, A; Hanlon, J; Harris, R M; Holzman, B; Howell, J; Hufnagel, D; James, E; Jensen, H; Johnson, M; Jones, C D; Joshi, U; Juska, E; Kaiser, J; Klima, B; Kossiakov, S; Kousouris, K; Kwan, S; Lei, C M; Limon, P; Lopez Perez, J A; Los, S; Lueking, L; Lukhanin, G; Lusin, S; Lykken, J; Maeshima, K; Marraffino, J M; Mason, D; McBride, P; Miao, T; Mishra, K; Moccia, S; Mommsen, R; Mrenna, S; Muhammad, A S; Newman-Holmes, C; Noeding, C; O'Dell, V; Prokofyev, O; Rivera, R; Rivetta, C H; Ronzhin, A; Rossman, P; Ryu, S; Sekhri, V; Sexton-Kennedy, E; Sfiligoi, I; Sharma, S; Shaw, T M; Shpakov, D; Skup, E; Smith, R P; Soha, A; Spalding, W J; Spiegel, L; Suzuki, I; Tan, P; Tanenbaum, W; Tkaczyk, S; Trentadue, R; Uplegger, L; Vaandering, E W; Vidal, R; Whitmore, J; Wicklund, E; Wu, W; Yarba, J; Yumiceva, F; Yun, J C; Acosta, D; Avery, P; Barashko, V; Bourilkov, D; Chen, M; Di Giovanni, G P; Dobur, D; Drozdetskiy, A; Field, R D; Fu, Y; Furic, I K; Gartner, J; Holmes, D; Kim, B; Klimenko, S; Konigsberg, J; Korytov, A; Kotov, K; Kropivnitskaya, A; Kypreos, T; Madorsky, A; Matchev, K; Mitselmakher, G; Pakhotin, Y; Piedra Gomez, J; Prescott, C; Rapsevicius, V; Remington, R; Schmitt, M; Scurlock, B; Wang, D; Yelton, J; Ceron, C; Gaultney, V; Kramer, L; Lebolo, L M; Linn, S; Markowitz, P; Martinez, G; Rodriguez, J L; Adams, T; Askew, A; Baer, H; Bertoldi, M; Chen, J; Dharmaratna, W G D; Gleyzer, S V; Haas, J; Hagopian, S; Hagopian, V; Jenkins, M; Johnson, K F; Prettner, E; Prosper, H; Sekmen, S; Baarmand, M M; Guragain, S; Hohlmann, M; Kalakhety, H; Mermerkaya, H; Ralich, R; Vodopiyanov, I; Abelev, B; Adams, M R; Anghel, I M; Apanasevich, L; Bazterra, V E; Betts, R R; Callner, J; Castro, M A; Cavanaugh, R; Dragoiu, C; Garcia-Solis, E J; Gerber, C E; Hofman, D J; Khalatian, S; Mironov, C; Shabalina, E; Smoron, A; Varelas, N; Akgun, U; Albayrak, E A; Ayan, A S; Bilki, B; Briggs, R; Cankocak, K; Chung, K; Clarida, W; Debbins, P; Duru, F; Ingram, F D; Lae, C K; McCliment, E; Merlo, J P; Mestvirishvili, A; Miller, M J; Moeller, A; Nachtman, J; Newsom, C R; Norbeck, E; Olson, J; Onel, Y; Ozok, F; Parsons, J; Schmidt, I; Sen, S; Wetzel, J; Yetkin, T; Yi, K; Barnett, B A; Blumenfeld, B; Bonato, A; Chien, C Y; Fehling, D; Giurgiu, G; Gritsan, A V; Guo, Z J; Maksimovic, P; Rappoccio, S; Swartz, M; Tran, N V; Zhang, Y; Baringer, P; Bean, A; Grachov, O; Murray, M; Radicci, V; Sanders, S; Wood, J S; Zhukova, V; Bandurin, D; Bolton, T; Kaadze, K; Liu, A; Maravin, Y; Onoprienko, D; Svintradze, I; Wan, Z; Gronberg, J; Hollar, J; Lange, D; Wright, D; Baden, D; Bard, R; Boutemeur, M; Eno, S C; Ferencek, D; Hadley, N J; Kellogg, R G; Kirn, M; Kunori, S; Rossato, K; Rumerio, P; Santanastasio, F; Skuja, A; Temple, J; Tonjes, M B; Tonwar, S C; Toole, T; Twedt, E; Alver, B; Bauer, G; Bendavid, J; Busza, W; Butz, E; Cali, I A; Chan, M; D'Enterria, D; Everaerts, P; Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of cosmic muons. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.

  5. Temporal Evolution of Ion Spectral Structures During a Geomagnetic Storm: Observations and Modeling

    Science.gov (United States)

    Ferradas, C. P.; Zhang, J.-C.; Spence, H. E.; Kistler, L. M.; Larsen, B. A.; Reeves, G. D.; Skoug, R. M.; Funsten, H. O.

    2018-01-01

    Using the Van Allen Probes/Helium, Oxygen, Proton, and Electron mass spectrometer, we perform a case study of the temporal evolution of ion spectral structures observed in the energy range of 1 to 50 keV throughout the geomagnetic storm of 2 October 2013. The ion spectral features are observed near the inner edge of the plasma sheet and are signatures of fresh transport from the plasma sheet into the inner magnetosphere. We find that the characteristics of the ion structures are determined by the intensity of the convection electric field. Prior to the beginning of the storm, the plasma sheet inner edge exhibits narrow nose spectral structures that vary little in energy across L values. Ion access to the inner magnetosphere during these times is limited to the nose energy bands. As convection is enhanced and large amounts of plasma are injected from the plasma sheet during the main phase of the storm, ion access occurs at a wide energy range, as no nose structures are observed. As the magnetosphere recovers from the storm, single noses and then multiple noses are observed once again. We use a model of ion drift and losses due to charge exchange to simulate the ion spectra and gain insight into the main observed features.

  6. Results based on a correlative study of geomagnetic and radio auroral observations

    International Nuclear Information System (INIS)

    Haldoupis, C.

    The results presented here are from a correlative study of ground based magnetometer data from an auroral station, and STARE radar auroral data from a small ionospheric region located exactly above the magnetometer site. The magnetometer data includes both the horizontal X and Y magnetograms and micropulsation components. The STARE data represents time sequencies of both the echo intensity and irregularity drift velocity (or electric field) vector. The observations used in the analysis are from a reasonably disturbed 16-hour period covering the afternoon, midnight and morning sectors of auroral oval. A close relationship was found to exist between the geomagnetic variations and the backscatter amplitude. The results suggest that the conductivity, rather than the electric field, is the prime agent responsible for the long period modulation observed on both the magnetic signatures and the backscatter intensity. In one case, it was found that conductivity modifications cause direct modulation of direction but not the amplitude of the electric field. The rapid ac-fluctuations seen in the electric field most likely play a role in the generation of Pi-pulsations. (Auth.)

  7. Surface electric fields and geomagnetically induced currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm

    OpenAIRE

    Thomson, Alan W.P.; McKay, Allan J.; Clarke, Ellen; Reay, Sarah J.

    2005-01-01

    A surface electric field model is used to estimate the UK surface E field during the 30 October 2003 severe geomagnetic storm. This model is coupled with a power grid model to determine the flow of geomagnetically induced currents (GIC) through the Scottish part of the UK grid. Model data are compared with GIC measurements at four sites in the power network. During this storm, measured and modeled GIC levels exceeded 40 A, and the surface electric field reached 5 V/km at sites in ...

  8. Strong drifts effects on neoclassical transport

    International Nuclear Information System (INIS)

    Tessarotto, M.; Gregoratto, D.; White, R.B.

    1996-01-01

    It is well known that strong drifts play an important role in plasma equilibrium, stability and confinement A significant example concerns, in particular for tokamak plasmas, the case of strong toroidal differential rotation produced by E x B drift which is currently regarded as potentially important for its influence in equilibrium, stability and transport. In fact, theoretically, it has been found that shear flow can substantially affect the stability of microinstabilities as well modify substantially transport. Recent experimental observations of enhanced confinement and transport regimes in Tokamaks, show, however, evidence of the existence of strong drifts in the plasma core. These are produced not only by the radial electric field [which gives rise to the E x B drift], but also by density [N s ], temperature [T s ] and mass flow [V = ωRe var-phi , with e var-phi the toroidal unit vector, R the distance for the symmetry axis of the torus and ω being the toroidal angular rotation velocity] profiles which are suitably steep. This implies that, in a significant part of the plasma core, the relevant scale lengths of the gradients [of N s , T s , ω], i.e., respectively L N , L T and L ω can be as large as the radial scale length characterizing the banana orbits, L b . Interestingly enough, the transport estimates obtained appear close or even lower than the predictions based on the simplest neoclassical model. However, as is well known, the latter applies, in a strict sense only in the case of weak drifts and also ignoring even the contribution of shear flow related to strong E x B drift. Thus a fundamental problem appears the extension of neoclassical transport theory to include the effect of strong drifts in Tokamak confinement systems. The goal of this investigation is to develop a general formulation of neoclassical transport embodying such important feature

  9. Protection of power transformers against geomagnetically induced currents

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2011-01-01

    Full Text Available The article examines the problem of saturation and failure of power transformers under geomagnetically induced currents and currents of the E3 component of high-altitude nuclear explosions. It also describes a special protective relay reacting on DC component in the transformer neutral current.

  10. Geomagnetic matching navigation algorithm based on robust estimation

    Science.gov (United States)

    Xie, Weinan; Huang, Liping; Qu, Zhenshen; Wang, Zhenhuan

    2017-08-01

    The outliers in the geomagnetic survey data seriously affect the precision of the geomagnetic matching navigation and badly disrupt its reliability. A novel algorithm which can eliminate the outliers influence is investigated in this paper. First, the weight function is designed and its principle of the robust estimation is introduced. By combining the relation equation between the matching trajectory and the reference trajectory with the Taylor series expansion for geomagnetic information, a mathematical expression of the longitude, latitude and heading errors is acquired. The robust target function is obtained by the weight function and the mathematical expression. Then the geomagnetic matching problem is converted to the solutions of nonlinear equations. Finally, Newton iteration is applied to implement the novel algorithm. Simulation results show that the matching error of the novel algorithm is decreased to 7.75% compared to the conventional mean square difference (MSD) algorithm, and is decreased to 18.39% to the conventional iterative contour matching algorithm when the outlier is 40nT. Meanwhile, the position error of the novel algorithm is 0.017° while the other two algorithms fail to match when the outlier is 400nT.

  11. Recent investigation at INPE in magnetospheric physics and geomagnetism

    International Nuclear Information System (INIS)

    Gonzales, W.D.; Trivedi, N.B.

    1984-01-01

    During recent years the following research activities related to the earth's magnetosphere have been intensified: a) studies on electric field and energy transfer from the solar wind to the magnetosphere; b) studies on high latitude magnetospheric electric fields and on their penetration into the plasmasphere; c) measurements of atmospheric-large scale-electric fields, related to the low latitude magnetospheric-ionospheric coupling and to the local atmospheric electrodynamics, using detectors on board stratospheric balloons; and d) measurements of atmospheric X-rays, related to the process of energetic particle precipitation at the South Atlantic Magnetic Anomaly, using detectors also on board stratospheric balloons. Similarly, the following research activities related to geomagnetism are being pursued: a) studies on the variability of the geomagnetic field and on the dynamics of the equatorial electrojet from local geomagnetic field measurements; b) studies on terrestrial electromagnetic induction through local measurements of the geo-electromagnetic field; and c) studies on the influence of geomagnetic activity on particle precipitation at the South Atlantic Magnetic Anomaly. (Author) [pt

  12. Methodology for simulation of geomagnetically induced currents in power systems

    Directory of Open Access Journals (Sweden)

    Boteler David

    2014-07-01

    Full Text Available To assess the geomagnetic hazard to power systems it is useful to be able to simulate the geomagnetically induced currents (GIC that are produced during major geomagnetic disturbances. This paper examines the methodology used in power system analysis and shows how it can be applied to modelling GIC. Electric fields in the area of the power network are used to determine the voltage sources or equivalent current sources in the transmission lines. The power network can be described by a mesh impedance matrix which is combined with the voltage sources to calculate the GIC in each loop. Alternatively the power network can be described by a nodal admittance matrix which is combined with the sum of current sources into each node to calculate the nodal voltages which are then used to calculate the GIC in the transmission lines and GIC flowing to ground at each substation. Practical calculations can be made by superposition of results calculated separately for northward and eastward electric fields. This can be done using magnetic data from a single observatory to calculate an electric field that is a uniform approximation of the field over the area of the power system. It is also shown how the superposition of results can be extended to use data from two observatories: approximating the electric field by a linear variation between the two observatory locations. These calculations provide an efficient method for simulating the GIC that would be produced by historically significant geomagnetic storm events.

  13. Evidence for a new geomagnetic jerk in 2014

    DEFF Research Database (Denmark)

    Torta, J. Miquel; Pavón-Carrasco, Francisco Javier; Marsal, Santiago

    2015-01-01

    The production of quasi-definitive data at Ebre observatory has enabled us to detect a new geomagnetic jerk in early 2014. This has been confirmed by analyzing data at several observatories in the European-African and Western Pacific-Australian sectors in the classical fashion of looking for the ...

  14. Long-term trends in geomagnetic and climatic variability

    Czech Academy of Sciences Publication Activity Database

    Bucha, Václav

    2002-01-01

    Roč. 27, 6/7 (2002), s. 427-731 ISSN 1474-7065 R&D Projects: GA AV ČR IAA3012806 Institutional research plan: CEZ:AV0Z3012916 Keywords : geomagnetic forcing * climatic variability * global warming Subject RIV: DE - Earth Magnetism, Geodesy, Geography

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

    Science.gov (United States)

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

    2013-01-01

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

  16. Geomagnetic core field models in the satellite era

    DEFF Research Database (Denmark)

    Lesur, Vincent; Olsen, Nils; Thomson, Alan W. P.

    2011-01-01

    After a brief review of the theoretical basis and difficulties that modelers are facing, we present three recent models of the geomagnetic field originating in the Earth’s core. All three modeling approaches are using recent observatory and near-Earth orbiting survey satellite data. In each case...

  17. New insights on geomagnetic storms from observations and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania K [Los Alamos National Laboratory

    2009-01-01

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

  18. The Ranges Of Subauroral Geomagnetic Field Elements | Rabiu ...

    African Journals Online (AJOL)

    Nigeria Journal of Pure and Applied Physics ... An anomaly in seasonal response of range at high solar activity is observed on disturbed condition. ... apart from the anomaly - maintain the order e>j>d of seasonal variation which is in agreement with the popular equinoctial maximum observed in geomagnetic activity.

  19. Eruptive prominences and long-delay geomagnetic storms

    International Nuclear Information System (INIS)

    Wright, C.S.

    1983-01-01

    The relationship between disappearing solar fragments and geomagnetic disturbances was investigated. It is shown that long-delay storms are associated with filaments well removed from the disc centre, and particularly in the case of large filaments and prominences, the proportion of events that produce long-delay storms increases with angular distance from the centre

  20. Effects of geomagnetic storms on the bottomside ionospheric F region

    Czech Academy of Sciences Publication Activity Database

    Burešová, Dalia

    2005-01-01

    Roč. 35, - (2005), s. 429-439 ISSN 0273-1177 R&D Projects: GA AV ČR(CZ) IAA3042102 Institutional research plan: CEZ:AV0Z30420517 Keywords : Ionosphere * Geomagnetic storm * Bottomside F region electron density Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.706, year: 2005

  1. Statistical Relationship between Sawtooth Oscillations and Geomagnetic Storms

    Directory of Open Access Journals (Sweden)

    Jae-Hun Kim

    2008-06-01

    Full Text Available 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. Transport from chaotic orbits in the geomagnetic tail

    International Nuclear Information System (INIS)

    Horton, W.; Tajima, T.

    1991-01-01

    The rapid change in direction and magnitude of the magnetic field vector in crossing the quasineutral sheet in the geomagnetic tail leads to deterministic Hamiltonian chaos. The finite correlation times in the single particle orbits due to the continuum of orbital frequencies leads to well-defined collisionless transport coefficients. The transport coefficients are derived for plasma trapped in the quasineutral sheet

  3. Linkage between the Biosphere and Geomagnetic field: Knowns and Unknowns

    Science.gov (United States)

    Pan, Y.; Zhu, R.

    2017-12-01

    The geomagnetic field extends from Earth's interior into space, and protects our planets habitability by shielding the planet from solar winds and cosmic rays. Recently, single zircon paleomagnetic study provides evidence of the field to ages as old as 4.2 Ga. Many great questions remain, including whether the emergence of life on Earth was a consequence of the field's protection, how organisms utilize the field, and if field variations (polarity reversal, excursion and secular variation) impact the evolution of the biosphere. In the past decade, great efforts have been made to probe these very complex and great challenging questions through the inter-disciplinary subject of biogeomagnetism. Numerous birds, fish, sea turtles, bats and many other organisms utilize the geomagnetic field during orientation and long-distance navigation. We recently found that bats, the second most abundant order of mammals, can use the direction of magnetic field with a weak strength comparable to polarity transitions/excursions, which is indicative of advanced magnetoreception developed in bats co-evolving with the geomagnetic field since the Eocene. Magnetotactic bacteria swim along the geomagnetic field lines by synthesizing intracellular nano-sized and chain-arranged magnetic minerals (magnetosomes). Recent field surveys in China, Europe, America and Australia have shown that these microbes are ubiquitous in aqueous habitats. Both their biogeography distribution and magnetotactic swimming speed are field intensity dependent. On the other hand, it is increasingly accepted that the geomagnetic field influences life through several indirect pathways. For example, it has been discovered that solar wind erosion enhanced the atmospheric oxygen escape during periods of weak magnetic field and global mean ionospheric electron density profiles can be affected by geomagnetic field strength variation. In addition, depletion of the ozone layer during a weak magnetic field could result in

  4. Single nozzle spray drift measurements of drift reducing nozzles at two forward speeds

    NARCIS (Netherlands)

    Stallinga, H.; Zande, van de J.C.; Michielsen, J.G.P.; Velde, van P.

    2016-01-01

    In 2011‒2012 single nozzle field experiments were carried out to determine the effect of different flat fan spray nozzles of the spray drift reduction classes 50, 75, 90 and 95% on spray drift at two different forward speeds (7.2 km h-1 and 14.4 km h-1). Experiments were performed with a single

  5. Relationship between vertical ExB drift and F2-layer characteristics in the equatorial ionosphere at solar minimum conditions

    Science.gov (United States)

    Oyekola, Oyedemi S.

    2012-07-01

    Equatorial and low-latitude electrodynamics plays a dominant role in determining the structure and dynamics of the equatorial and low-latitude ionospheric F-region. Thus, they constitute essential input parameters for quantitative global and regional modeling studies. In this work, hourly median value of ionosonde measurements namely, peak height F2-layer (hmF2), F2-layer critical frequency (foF2) and propagation factor M(3000)F2 made at near equatorial dip latitude, Ouagadougou, Burkina Faso (12oN, 1.5oW; dip: 1.5oN) and relevant F2-layer parameters such as thickness parameter (Bo), electron temperature (Te), ion temperature (Ti), total electron content (TEC) and electron density (Ne, at the fixed altitude of 300 km) provided by the International Reference Ionosphere (IRI) model for the longitude of Ouagadougou are contrasted with the IRI vertical drift model to explore in detail the monthly climatological behavior of equatorial ionosphere and the effects of equatorial vertical plasma drift velocities on the diurnal structure of F2-layer parameters. The analysis period covers four months representative of solstitial and equinoctial seasonal periods during solar minimum year of 1987 for geomagnetically quiet-day. We show that month-by-month morphological patterns between vertical E×B drifts and F2-layer parameters range from worst to reasonably good and are largely seasonally dependent. A cross-correlation analysis conducted between equatorial drift and F2-layer characteristics yield statistically significant correlations for equatorial vertical drift and IRI-Bo, IRI-Te and IRI-TEC, whereas little or no acceptable correlation is obtained with observational evidence. Assessment of the association between measured foF2, hmF2 and M(3000)F2 illustrates consistent much more smaller correlation coefficients with no systematic linkage. In general, our research indicates strong departure from simple electrodynamically controlled behavior.

  6. Statistical Properties of Geomagnetic Activity Indices and Solar Wind Parameters

    Directory of Open Access Journals (Sweden)

    Jung-Hee Kim

    2014-06-01

    Full Text Available As the prediction of geomagnetic storms is becoming an important and practical problem, conditions in the Earth’s magnetosphere have been studied rigorously in terms of those in the interplanetary space. Another approach to space weather forecast is to deal with it as a probabilistic geomagnetic storm forecasting problem. In this study, we carry out detailed statistical analysis of solar wind parameters and geomagnetic indices examining the dependence of the distribution on the solar cycle and annual variations. Our main findings are as follows: (1 The distribution of parameters obtained via the superimposed epoch method follows the Gaussian distribution. (2 When solar activity is at its maximum the mean value of the distribution is shifted to the direction indicating the intense environment. Furthermore, the width of the distribution becomes wider at its maximum than at its minimum so that more extreme case can be expected. (3 The distribution of some certain heliospheric parameters is less sensitive to the phase of the solar cycle and annual variations. (4 The distribution of the eastward component of the interplanetary electric field BV and the solar wind driving function BV2, however, appears to be all dependent on the solar maximum/minimum, the descending/ascending phases of the solar cycle and the equinoxes/solstices. (5 The distribution of the AE index and the Dst index shares statistical features closely with BV and BV2 compared with other heliospheric parameters. In this sense, BV and BV2 are more robust proxies of the geomagnetic storm. We conclude by pointing out that our results allow us to step forward in providing the occurrence probability of geomagnetic storms for space weather and physical modeling.

  7. Optical drift effects in general relativity

    Science.gov (United States)

    Korzyński, Mikołaj; Kopiński, Jarosław

    2018-03-01

    We consider the question of determining the optical drift effects in general relativity, i.e. the rate of change of the apparent position, redshift, Jacobi matrix, angular distance and luminosity distance of a distant object as registered by an observer in an arbitrary spacetime. We present a fully relativistic and covariant approach, in which the problem is reduced to a hierarchy of ODE's solved along the line of sight. The 4-velocities and 4-accelerations of the observer and the emitter and the geometry of the spacetime along the line of sight constitute the input data. We build on the standard relativistic geometric optics formalism and extend it to include the time derivatives of the observables. In the process we obtain two general, non-perturbative relations: the first one between the gravitational lensing, represented by the Jacobi matrix, and the apparent position drift, also called the cosmic parallax, and the second one between the apparent position drift and the redshift drift. The applications of the results include the theoretical study of the drift effects of cosmological origin (so-called real-time cosmology) in numerical or exact Universe models.

  8. Drift chamber performance in the field of a superconducting magnet: measurement of the drift angle

    International Nuclear Information System (INIS)

    Sanders, G.H.; Sherman, S.; McDonald, K.T.; Smith, A.J.S.; Thaler, J.J.

    1977-01-01

    Results are presented of the first measurements in a study of drift chamber performance in magnetic fields up to 6 tesla. The angle of the electron drift was measured as a function of electric and magnetic field intensity. It appears that even at the high fields of superconducting magnets (3 to 6 tesla) the drift angle induced by the Lorentz force can be corrected for with tilted electric drift fields and/or the use of Xenon gas. At 3 tesla a drift field tilted at 45 0 with a magnitude of 3.5 kV/cm should restore normal operating conditions. At 4 tesla, a 45 0 tilt field would have a magnitude 5 kV/cm

  9. LANL* V1.0: a radiation belt drift shell model suitable for real-time and reanalysis applications

    Directory of Open Access Journals (Sweden)

    J. Koller

    2009-07-01

    Full Text Available We describe here a new method for calculating the magnetic drift invariant, L*, that is used for modeling radiation belt dynamics and for other space weather applications. L* (pronounced L-star is directly proportional to the integral of the magnetic flux contained within the surface defined by a charged particle moving in the Earth's geomagnetic field. Under adiabatic changes to the geomagnetic field L* is a conserved quantity, while under quasi-adiabatic fluctuations diffusion (with respect to a particle's L* is the primary term in equations of particle dynamics. In particular the equations of motion for the very energetic particles that populate the Earth's radiation belts are most commonly expressed by diffusion in three dimensions: L*, energy (or momentum, and pitch angle (the dot product of velocity and the magnetic field vector. Expressing dynamics in these coordinates reduces the dimensionality of the problem by referencing the particle distribution functions to values at the magnetic equatorial point of a magnetic "drift shell" (or L-shell irrespective of local time (or longitude. While the use of L* aids in simplifying the equations of motion, practical applications such as space weather forecasting using realistic geomagnetic fields require sophisticated magnetic field models that, in turn, require computationally intensive numerical integration. Typically a single L* calculation can require on the order of 105 calls to a magnetic field model and each point in the simulation domain and each calculated pitch angle has a different value of L*. We describe here the development and validation of a neural network surrogate model for calculating L* in sophisticated geomagnetic field models with a high degree of fidelity at computational speeds that are millions of times faster than direct numerical field line mapping and integration. This new surrogate model has

  10. Spray particle drift mitigation using field corn (Zea mays L.) as a drift barrier.

    Science.gov (United States)

    Vieira, Bruno C; Butts, Thomas R; Rodrigues, Andre O; Golus, Jeffrey A; Schroeder, Kasey; Kruger, Greg R

    2018-04-24

    Herbicide particle drift reduces application efficacy and can cause severe impacts on nearby vegetation depending on the herbicide mode-of-action, exposure level, and tolerance to the herbicide. A particle drift mitigation effort placing windbreaks or barriers on the field boundaries to reduce off-target movement of spray particles has been utilized in the past. The objective of this research was to evaluate the effectiveness of field corn (Zea mays L.) at different heights as a particle drift barrier. Applications with a non-air inclusion flat fan nozzle (ER11004) resulted in greater particle drift when compared to an air inclusion nozzle (TTI11004). Eight rows of corn were used as barriers (0.91, 1.22, and 1.98 m height) which reduced the particle drift for both nozzles, especially at shorter downwind distances. Applications with the ER11004 nozzle without corn barriers had 1% of the applied rate (D 99 ) predicted to deposit at 14.8 m downwind, whereas this distance was reduced (up to 7-fold) when applications were performed with corn barriers. The combination of corn drift barriers and nozzle selection (TTI11004) provided satisfactory particle drift reduction when the D 99 estimates were compared to applications with the ER11004 nozzle without corn barriers (up to 10-fold difference). The corn drift barriers were effective in reducing particle drift from applications with the ER11004 and the TTI11004 nozzles (Fine and Ultra Coarse spray classifications, respectively). The corn drift barrier had appropriate porosity and width as the airborne spray was captured within its canopy instead of deflecting up and over it. This article is protected by copyright. All rights reserved.

  11. Approximate Stokes Drift Profiles in Deep Water

    Science.gov (United States)

    Breivik, Øyvind; Janssen, Peter A. E. M.; Bidlot, Jean-Raymond

    2014-09-01

    A deep-water approximation to the Stokes drift velocity profile is explored as an alternative to the monochromatic profile. The alternative profile investigated relies on the same two quantities required for the monochromatic profile, viz the Stokes transport and the surface Stokes drift velocity. Comparisons with parametric spectra and profiles under wave spectra from the ERA-Interim reanalysis and buoy observations reveal much better agreement than the monochromatic profile even for complex sea states. That the profile gives a closer match and a more correct shear has implications for ocean circulation models since the Coriolis-Stokes force depends on the magnitude and direction of the Stokes drift profile and Langmuir turbulence parameterizations depend sensitively on the shear of the profile. The alternative profile comes at no added numerical cost compared to the monochromatic profile.

  12. P-type silicon drift detectors

    International Nuclear Information System (INIS)

    Walton, J.T.; Krieger, B.; Krofcheck, D.; O'Donnell, R.; Odyniec, G.; Partlan, M.D.; Wang, N.W.

    1995-06-01

    Preliminary results on 16 CM 2 , position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 x l0 6 s -1 is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 μm to 1200 μm. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed

  13. Correcting sample drift using Fourier harmonics.

    Science.gov (United States)

    Bárcena-González, G; Guerrero-Lebrero, M P; Guerrero, E; Reyes, D F; Braza, V; Yañez, A; Nuñez-Moraleda, B; González, D; Galindo, P L

    2018-07-01

    During image acquisition of crystalline materials by high-resolution scanning transmission electron microscopy, the sample drift could lead to distortions and shears that hinder their quantitative analysis and characterization. In order to measure and correct this effect, several authors have proposed different methodologies making use of series of images. In this work, we introduce a methodology to determine the drift angle via Fourier analysis by using a single image based on the measurements between the angles of the second Fourier harmonics in different quadrants. Two different approaches, that are independent of the angle of acquisition of the image, are evaluated. In addition, our results demonstrate that the determination of the drift angle is more accurate by using the measurements of non-consecutive quadrants when the angle of acquisition is an odd multiple of 45°. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    2004-11-01

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

  15. Mean Lagrangian drift in continental shelf waves

    Science.gov (United States)

    Drivdal, M.; Weber, J. E. H.

    2012-04-01

    The time- and depth-averaged mean drift induced by barotropic continental shelf waves (CSW's) is studied theoretically for idealized shelf topography by calculating the mean volume fluxes to second order in wave amplitude. The waves suffer weak spatial damping due to bottom friction, which leads to radiation stress forcing of the mean fluxes. In terms of the total wave energy density E¯ over the shelf region, the radiation stress tensor component S¯11 for CSW's is found to be different from that of shallow water surface waves in a non-rotating ocean. For CSW's, the ratio ¯S11/¯E depends strongly on the wave number. The mean Lagrangian flow forced by the radiation stress can be subdivided into a Stokes drift and a mean Eulerian drift current. The magnitude of the latter depends on the ratio between the radiation stress and the bottom stress acting on the mean flow. When the effect of bottom friction acts equally strong on the waves and the mean current, calculations for short CSW's show that the Stokes drift and the friction-dependent wave-induced mean Eulerian current varies approximately in anti-phase over the shelf, and that the latter is numerically the largest. For long CSW's they are approximately in phase. In both cases the mean Lagrangian current, which is responsible for the net particle drift, has its largest numerical value at the coast on the shallow part of the shelf. Enhancing the effect of bottom friction on the Eulerian mean flow, results in a general current speed reduction, as well as a change in spatial structure for long waves. Applying realistic physical parameters for the continental shelf west of Norway, calculations yield along-shelf mean drift velocities for short CSW's that may be important for the transport of biological material, neutral tracers, and underwater plumes of dissolved oil from deep water drilling accidents.

  16. Accurate computer simulation of a drift chamber

    International Nuclear Information System (INIS)

    Killian, T.J.

    1980-01-01

    A general purpose program for drift chamber studies is described. First the capacitance matrix is calculated using a Green's function technique. The matrix is used in a linear-least-squares fit to choose optimal operating voltages. Next the electric field is computed, and given knowledge of gas parameters and magnetic field environment, a family of electron trajectories is determined. These are finally used to make drift distance vs time curves which may be used directly by a track reconstruction program. Results are compared with data obtained from the cylindrical chamber in the Axial Field Magnet experiment at the CERN ISR

  17. Drift estimation from a simple field theory

    International Nuclear Information System (INIS)

    Mendes, F. M.; Figueiredo, A.

    2008-01-01

    Given the outcome of a Wiener process, what can be said about the drift and diffusion coefficients? If the process is stationary, these coefficients are related to the mean and variance of the position displacements distribution. However, if either drift or diffusion are time-dependent, very little can be said unless some assumption about that dependency is made. In Bayesian statistics, this should be translated into some specific prior probability. We use Bayes rule to estimate these coefficients from a single trajectory. This defines a simple, and analytically tractable, field theory.

  18. Ultra-low mass drift chambers

    International Nuclear Information System (INIS)

    Assiro, R.; Cappelli, L.; Cascella, M.; De Lorenzis, L.; Grancagnolo, F.; Ignatov, F.; L'Erario, A.; Maffezzoli, A.; Miccoli, A.; Onorato, G.; Perillo, M.; Piacentino, G.; Rella, S.; Rossetti, F.; Spedicato, M.; Tassielli, G.

    2013-01-01

    We present a novel low mass drift chamber concept, developed in order to fulfill the stringent requirements imposed by the experiments for extremely rare processes, which require high resolutions (order of 100–200 keV/c) for particle momenta in a range (50–100 MeV/c) totally dominated by the multiple scattering contribution. We describe a geometry optimization procedure and a new wiring strategy with a feed-through-less wire anchoring system developed and tested on a drift chamber prototype under completion at INFN-Lecce

  19. Ultra-low mass drift chambers

    Science.gov (United States)

    Assiro, R.; Cappelli, L.; Cascella, M.; De Lorenzis, L.; Grancagnolo, F.; Ignatov, F.; L'Erario, A.; Maffezzoli, A.; Miccoli, A.; Onorato, G.; Perillo, M.; Piacentino, G.; Rella, S.; Rossetti, F.; Spedicato, M.; Tassielli, G.; Zavarise, G.

    2013-08-01

    We present a novel low mass drift chamber concept, developed in order to fulfill the stringent requirements imposed by the experiments for extremely rare processes, which require high resolutions (order of 100-200 keV/c) for particle momenta in a range (50-100 MeV/c) totally dominated by the multiple scattering contribution. We describe a geometry optimization procedure and a new wiring strategy with a feed-through-less wire anchoring system developed and tested on a drift chamber prototype under completion at INFN-Lecce .

  20. Properties of low-pressure drift chambers

    International Nuclear Information System (INIS)

    Breskin, A.; Trautner, N.

    1976-01-01

    Drift chambers operated with methylal vapour or ethylene at pressures in the range of 10-110 torr are described. A systematic study of position resolution, pulse height and rise time shows that especially for ethylene they are strongly influenced by electron diffusion. Intrinsic position resolution was found to be at least as good as found at atmospheric pressure. A relative pulse height resolution of 10% was obtained with 5.5 MeV alpha-particles. A simple mathematical model which can describe the processes in the drift chamber is presented. (Auth.)

  1. Silicon Drift Detectors development for position sensing

    International Nuclear Information System (INIS)

    Castoldi, A.; Guazzoni, C.; Hartmann, R.; Strueder, L.

    2007-01-01

    Novel Silicon Drift Detectors (SDDs) with multi-linear architecture specifically intended for 2D position sensing and imaging applications are presented and their achievable spatial, energy and time resolution are discussed. The capability of providing a fast timing of the interaction with nanosecond time resolution is a new available feature that allows operating the drift detector in continuous readout mode for coincidence imaging applications either with an external trigger or in self-timing. The application of SDDs with multi-linear architecture to Compton electrons' tracking within a single silicon layer and the achieved experimental results will be discussed

  2. Nonlinear dynamics of resistive electrostatic drift waves

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Michelsen, Poul; Pécseli, H.L.

    1999-01-01

    The evolution of weakly nonlinear electrostatic drift waves in an externally imposed strong homogeneous magnetic field is investigated numerically in three spatial dimensions. The analysis is based on a set of coupled, nonlinear equations, which are solved for an initial condition which is pertur......The evolution of weakly nonlinear electrostatic drift waves in an externally imposed strong homogeneous magnetic field is investigated numerically in three spatial dimensions. The analysis is based on a set of coupled, nonlinear equations, which are solved for an initial condition which...... polarity, i.e. a pair of electrostatic convective cells....

  3. Accurate computer simulation of a drift chamber

    CERN Document Server

    Killian, T J

    1980-01-01

    The author describes a general purpose program for drift chamber studies. First the capacitance matrix is calculated using a Green's function technique. The matrix is used in a linear-least-squares fit to choose optimal operating voltages. Next the electric field is computed, and given knowledge of gas parameters and magnetic field environment, a family of electron trajectories is determined. These are finally used to make drift distance vs time curves which may be used directly by a track reconstruction program. The results are compared with data obtained from the cylindrical chamber in the Axial Field Magnet experiment at the CERN ISR. (1 refs).

  4. Small-scale lacustrine drifts in Lake Champlain, Vermont

    Science.gov (United States)

    Manley, Patricia L.; Manley, T.O.; Hayo, Kathryn; Cronin, Thomas

    2012-01-01

    High resolution CHIRP (Compressed High Intensity Radar Pulse) seismic profiles reveal the presence of two lacustrine sediment drifts located in Lake Champlain's Juniper Deep. Both drifts are positive features composed of highly laminated sediments. Drift B sits on a basement high while Drift A is built on a trough-filling acoustically-transparent sediment unit inferred to be a mass-transport event. These drifts are oriented approximately north–south and are parallel to a steep ridge along the eastern shore of the basin. Drift A, located at the bottom of a structural trough, is classified as a confined, elongate drift that transitions northward to become a system of upslope asymmetric mudwaves. Drift B is perched atop a structural high to the west of Drift A and is classified as a detached elongate drift. Bottom current depositional control was investigated using Acoustic Doppler Current Profilers (ADCPs) located across Drift A. Sediment cores were taken at the crest and at the edges of the Drift A and were dated. Drift source, deposition, and evolution show that these drifts are formed by a water column shear with the highest deposition occurring along its crest and western flank and began developing circa 8700–8800 year BP.

  5. A new variable transformation technique for the nonlinear drift vortex

    International Nuclear Information System (INIS)

    Orito, Kohtaro

    1996-02-01

    The dipole vortex solution of the Hasegawa-Mima equation describing the nonlinear drift wave is a stable solitary wave which is called the modon. The profile of the modon depends on the nonlinearity of the ExB drift. In order to investigate the nonlinear drift wave more accurately, the effect of the polarization drift needs to be considered. In case of containing the effect of the polarization drift the profile of the electrostatic potential is distorted in the direction perpendicular to the ExB drift. (author)

  6. Psychometric Consequences of Subpopulation Item Parameter Drift

    Science.gov (United States)

    Huggins-Manley, Anne Corinne

    2017-01-01

    This study defines subpopulation item parameter drift (SIPD) as a change in item parameters over time that is dependent on subpopulations of examinees, and hypothesizes that the presence of SIPD in anchor items is associated with bias and/or lack of invariance in three psychometric outcomes. Results show that SIPD in anchor items is associated…

  7. Resistive drift wave turbulence and transport

    International Nuclear Information System (INIS)

    Wakatani, M.

    1986-01-01

    Our efforts for studying the properties of resistive drift wave turbulence by using model mode-coupling equations are shown. It may be related to the edge turbulence and the associated anomalous transport in tokamaks or in stellarator/heliotron. (author)

  8. Effects of Drifting Macroalgae in Eelgrass Ecosystems

    DEFF Research Database (Denmark)

    Canal Vergés, Paula; Valdemarsen, Thomas Bruun; Kristensen, Erik

    2010-01-01

    and physical damage on eelgrass can occur when macroalgae are drifting as bedload. The ballistic effect of moving macroalgae on surface sediment was tested in the field as well as in a series of annular flume experiments, where simultaneous measurements of macroalgae transport and turbidity were measured...

  9. EU law revisions and legislative drift

    DEFF Research Database (Denmark)

    Borghetto, Enrico; Mäder, Lars Kai

    2014-01-01

    in force in their original form for several years while others are revised soon after their enactment. What factors account for this variation? We empirically analyze the proposition that in the presence of ‘legislative drift,’ i.e. the intertemporal variation of decision-makers’ preferences, major...

  10. Nonlinear radial propagation of drift wave turbulence

    International Nuclear Information System (INIS)

    Prakash, M.

    1985-01-01

    We study the linear and the nonlinear radial propagation of drift wave energy in an inhomogeneous plasma. The drift mode excited in such a plasma is dispersive in nature. The drift wave energy spreads out symmetrically along the direction of inhomogeneity with a finite group velocity. To study the effect of the nonlinear coupling on the propagation of energy in a collision free plasma, we solve the Hasegawa-Mima equation as a mixed initial boundary-value problem. The solutions of the linearized equation are used to check the reliability of our numerical calculations. Additional checks are also performed on the invariants of the system. Our results reveal that a pulse gets distorted as it propagates through the medium. The peak of the pulse propagates with a finite velocity that depends on the amplitude of the initial pulse. The polarity of propagation depends on the initial parameters of the pulse. We have also studied drift wave propagation in a resistive plasma. The Hasegawa-Wakatani equations are used to investigate this problem

  11. Study and analysis of drift chamber parameters

    International Nuclear Information System (INIS)

    Martinez Laso, L.

    1988-01-01

    The present work deals mainly with drift chambers. In the first chapter a summary of drift chamber properties is presented. The information has been collected from the extensive bibliography available in this field. A very simple calculation procedure of drift chamber parameters has been developed and is presented in detail in the second chapter. Some prototypes have been made following two geometries (multidrift chamber and Z-chambers). Several installations have been used for test and calibration of these prototypes. A complete description of these installations is given in the third chapter. Cosmic rays, beta particles from a Ru106 radiactive source and a test beam in the WA (West Area) of SPS at CERN have been used for experimental purposes. The analysis and the results are described for the different setups. The experimental measurements have been used to produce a complete cell parametrization (position as function of drift time) and to obtain spatial resolution values (in the range of 200-250 um). Experimental results are in good agreement with numerical calculations. (Author)

  12. Drift wave in pair-ion plasma

    Indian Academy of Sciences (India)

    ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.

  13. Learning in the context of distribution drift

    Science.gov (United States)

    2017-05-09

    Figure 3 shows a heatmap of the pairwise drift in the joint distribution on the Landsat-8 French land usage satellite data. This data represents 10 meter...listed under the List of Publications. 1. White, C., Using Big Data for Smarter Decision Making. 2011, BI Research: Ashland, Or. 2. Cook , S., et al

  14. Comment on the drift mirror instability

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr

    2008-01-01

    Roč. 15, č. 5 (2008), 054502/1-054502/2 ISSN 1070-664X R&D Projects: GA AV ČR IAA300420702 Institutional research plan: CEZ:AV0Z30420517 Keywords : drift mirror instability * linear theory Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.427, year: 2008

  15. Sealed drift tube cosmic ray veto counters

    International Nuclear Information System (INIS)

    Rios, R.; Tatar, E.; Bacon, J.D.; Bowles, T.J.; Hill, R.; Green, J.A.; Hogan, G.E.; Ito, T.M.; Makela, M.; Morris, C.L.; Mortenson, R.; Pasukanics, F.E.; Ramsey, J.; Saunders, A.; Seestrom, S.J.; Sondheim, W.E.; Teasdale, W.; Saltus, M.; Back, H.O.; Cottrell, C.R.

    2011-01-01

    We describe a simple drift tube counter that has been used as a cosmic ray veto for the UCNA experiment, a first-ever measurement of the neutron beta-asymmetry using ultra-cold neutrons. These detectors provide an inexpensive alternative to more conventional scintillation detectors for large area cosmic ray anticoincidence detectors.

  16. Learning drifting concepts with neural networks

    NARCIS (Netherlands)

    Biehl, Michael; Schwarze, Holm

    1993-01-01

    The learning of time-dependent concepts with a neural network is studied analytically and numerically. The linearly separable target rule is represented by an N-vector, whose time dependence is modelled by a random or deterministic drift process. A single-layer network is trained online using

  17. Fine structure in fast drift storm bursts

    International Nuclear Information System (INIS)

    McConnell, D.; Ellis, G.R.A.

    1981-01-01

    Recent observations with high time resolution of fast drift storm (FDS) solar bursts are described. A new variety of FDS bursts characterised by intensity maxima regularly placed in the frequency domain is reported. Possible interpretations of this are mentioned and the implications of the short duration of FDS bursts are discussed. (orig.)

  18. Low-altitude trapped protons at the geomagnetic equator

    Science.gov (United States)

    Guzik, T. G.; Miah, M. A.; Mitchell, J. M.; Wefel, J. P.

    1989-01-01

    Geomagnetically trapped protons in the 0.6- to 9-MeV energy range were measured at latitudes near the geomagnetic equator by the Phoenix 1 experiment on board the S81-1 mission from May to November 1982. The protons show a distribution in latitude along the line of minimum magnetic field strength with a full width at half maximum of about 10 deg but with no appreciable longitudinal variation. Between 170 and 290 Km the peak proton flux shows a fifth-power altitude dependence, in contrast to previous measurements at higher altitudes, possibly demonstrating source attenuation. The efficiency of the telescope is calculated as a function of particle pitch angle and used to investigate the time dependence (1969-1982) of the intensity.

  19. Low-altitude trapped protons at the geomagnetic equator

    International Nuclear Information System (INIS)

    Guzik, T.G.; Miah, M.A.; Mitchell, J.W.; Wefel, J.P.

    1989-01-01

    Geomagnetically trapped protons in the 0.6- to 9-MeV energy range were measured at latitudes near the geomagnetic equator by the Phoenix 1 experiment on board the S81-1 mission from May to November 1982. The protons show a distribution in latitude along the line of minimum magnetic field strength with a full width at half maximum of ∼10 0 but with no appreciable longitudinal variation. Between 170 and 290 km the peak proton flux shows a fifth-power altitude dependence, in contrast to previous measurements at higher altitudes, possibly demonstrating source attenuation. The efficiency of the telescope is calculated as a function of particle pitch angle and used to investigate the time dependence (1969--1982) of the intensity. copyright American Geophysical Union 1989

  20. The International Geomagnetic Reference Field: the twelfth generation

    Science.gov (United States)

    Thebault, Erwan; Finlay, Christopher; The IGRF Working Group

    2015-04-01

    The IGRF is an internationally-agreed reference model of the Earth's magnetic field produced under the auspices of the International Association of Geomagnetism and Aeronomy. The IGRF-12 is the latest update of this well-known model which is used each year by many thousands of users for both industrial and scientific purposes. In October 2014, ten institutions worldwide have made contributions to the IGRF. These models were evaluated and the twelfth generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014. In this presentation, we will report on the IGRF activities, briefly describe the candidate models, summarize the evaluation of models performed by different independent teams, show how the IGRF-12 models were calculated and finally discuss some of the main magnetic features of this new model.

  1. Forecasting intense geomagnetic activity using interplanetary magnetic field data

    Science.gov (United States)

    Saiz, E.; Cid, C.; Cerrato, Y.

    2008-12-01

    Southward interplanetary magnetic fields are considered traces of geoeffectiveness since they are a main agent of magnetic reconnection of solar wind and magnetosphere. The first part of this work revises the ability to forecast intense geomagnetic activity using different procedures available in the literature. The study shows that current methods do not succeed in making confident predictions. This fact led us to develop a new forecasting procedure, which provides trustworthy results in predicting large variations of Dst index over a sample of 10 years of observations and is based on the value Bz only. The proposed forecasting method appears as a worthy tool for space weather purposes because it is not affected by the lack of solar wind plasma data, which usually occurs during severe geomagnetic activity. Moreover, the results obtained guide us to provide a new interpretation of the physical mechanisms involved in the interaction between the solar wind and the magnetosphere using Faraday's law.

  2. A new regard about Surlari National Geomagnetic Observatory

    Science.gov (United States)

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

    2010-05-01

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

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

    Science.gov (United States)

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

    2015-12-16

    Past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms ( D s t  > -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. Geomagnetic storms in the Antarctic F-region

    International Nuclear Information System (INIS)

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

    1987-01-01

    New analysis procedures are used to show that the main phase mid-latitude storm effects conform to consistent patterns in local time when suitable selection rules are applied, with averaging over several years. Changes in the maximum plasma frequency, foF2, with respect to estimated quiet-time values, are analysed in terms of asub(p)(t), a new geomagnetic index derived to take account of integrated disturbance. Reduction of foF2 is greatest during the early morning hours, in summer, at higher geomagnetic latitudes, near solar minimum and through the more active periods. The various dependencies are quantitatively determined for the first time by creating an average 'steady state' disturbance, rather than following specific storm events. This approach permits tests of competing theories using available modelling programs. (author)

  5. Modeling Geomagnetic Variations using a Machine Learning Framework

    Science.gov (United States)

    Cheung, C. M. M.; Handmer, C.; Kosar, B.; Gerules, G.; Poduval, B.; Mackintosh, G.; Munoz-Jaramillo, A.; Bobra, M.; Hernandez, T.; McGranaghan, R. M.

    2017-12-01

    We present a framework for data-driven modeling of Heliophysics time series data. The Solar Terrestrial Interaction Neural net Generator (STING) is an open source python module built on top of state-of-the-art statistical learning frameworks (traditional machine learning methods as well as deep learning). To showcase the capability of STING, we deploy it for the problem of predicting the temporal variation of geomagnetic fields. The data used includes solar wind measurements from the OMNI database and geomagnetic field data taken by magnetometers at US Geological Survey observatories. We examine the predictive capability of different machine learning techniques (recurrent neural networks, support vector machines) for a range of forecasting times (minutes to 12 hours). STING is designed to be extensible to other types of data. We show how STING can be used on large sets of data from different sensors/observatories and adapted to tackle other problems in Heliophysics.

  6. No alignment of cattle along geomagnetic field lines found

    OpenAIRE

    Hert, J.; Jelinek, L.; Pekarek, L.; Pavlicek, A.

    2011-01-01

    This paper presents a study of the body orientation of domestic cattle on free pastures in several European states, based on Google satellite photographs. In sum, 232 herds with 3412 individuals were evaluated. Two independent groups participated in our study and came to the same conclusion that, in contradiction to the recent findings of other researchers, no alignment of the animals and of their herds along geomagnetic field lines could be found. Several possible reasons for this discrepanc...

  7. Space Weather Monitoring for ISS Geomagnetic Storm Studies

    Science.gov (United States)

    Minow, Joseph I.; Parker, Linda Neergaard

    2013-01-01

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

  8. Geomagnetic Observatory Data for Real-Time Applications

    Science.gov (United States)

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

    2015-12-01

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

  9. Geomagnetic activity effects on plasma sheet energy conversion

    Directory of Open Access Journals (Sweden)

    M. Hamrin

    2010-10-01

    Full Text Available In this article we use three years (2001, 2002, and 2004 of Cluster plasma sheet data to investigate what happens to localized energy conversion regions (ECRs in the plasma sheet during times of high magnetospheric activity. By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we have studied the influence on Concentrated Load Regions (CLRs and Concentrated Generator Regions (CGRs from variations in the geomagnetic disturbance level as expressed by the Kp, the AE, and the Dst indices. We find that the ECR occurrence frequency increases during higher magnetospheric activities, and that the ECRs become stronger. This is true both for CLRs and for CGRs, and the localized energy conversion therefore concerns energy conversion in both directions between the particles and the fields in the plasma sheet. A higher geomagnetic activity hence increases the general level of energy conversion in the plasma sheet. Moreover, we have shown that CLRs live longer during magnetically disturbed times, hence converting more electromagnetic energy. The CGR lifetime, on the other hand, seems to be unaffected by the geomagnetic activity level. The evidence for increased energy conversion during geomagnetically disturbed times is most clear for Kp and for AE, but there are also some indications that energy conversion increases during large negative Dst. This is consistent with the plasma sheet magnetically mapping to the auroral zone, and therefore being more tightly coupled to auroral activities and variations in the AE and Kp indices, than to variations in the ring current region as described by the Dst index.

  10. Double streams of protons in the distant geomagnetic tail

    Science.gov (United States)

    Villante, U.; Lazarus, A. J.

    1975-01-01

    Two intermingled streams of protons have been observed in the distant geomagnetic tail. The number densities of the two streams are comparable, and their velocity difference tends to lie along the field direction. The lower-velocity stream is probably composed of magnetosheath protons which have diffused through the boundary of the distant tail. The higher-velocity stream appears to originate in the field reversal region.

  11. The Holocene Geomagnetic Field: Spikes, Low Field Anomalies, and Asymmetries

    Science.gov (United States)

    Constable, C.

    2017-12-01

    Our understanding of the Holocene magnetic field is constrained by individual paleomagnetic records of variable quality and resolution, composite regional secular variation curves, and low resolution global time-varying geomagnetic field models. Although spatial and temporal data coverages have greatly improved in recent years, typical views of millennial-scale secular variation and the underlying physical processes continue to be heavily influenced by more detailed field structure and short term variability inferred from the historical record and modern observations. Recent models of gyre driven decay of the geomagnetic dipole on centennial time scales, and studies of the evolution of the South Atlantic Anomaly provide one prominent example. Since 1840 dipole decay has largely been driven by meridional flux advection, with generally smaller fairly steady contributions from magnetic diffusion. The decay is dominantly associated with geomagnetic activity in the Southern Hemisphere. In contrast to the present decay, dipole strength generally grew between 1500 and 1000 BC, sustaining high but fluctuating values around 90-100 ZAm2 until after 1500 AD. Thus high dipole moments appear to have been present shortly after 1000 AD at the time of the Levantine spikes, which represent extreme variations in regional geomagnetic field strength. It has been speculated that the growth in dipole moment originated from a strong flux patch near the equatorial region at the core-mantle boundary that migrated north and west to augment the dipole strength, suggesting the presence of a large-scale anticyclonic gyre in the northern hemisphere, not totally unlike the southern hemisphere flow that dominates present day dipole decay. The later brief episodes of high field strength in the Levant may have contributed to prolonged values of high dipole strength until the onset of dipole decay in the late second millennium AD. This could support the concept of a large-scale stable flow

  12. Geomagnetic secular variation at Addis Ababa over the last four ...

    African Journals Online (AJOL)

    Addis Ababa Observatory (aae) geomagnetic data analysed over the time-span 1958—1998 show that the annual mean values of the intensity have decreased since 1965 from 36186 nT to 35950 nT at a non-linear regression rate of 8—9 nT per year. Directional changes in the Earth's magnetic field that could be ...

  13. Modeling geomagnetic induced currents in Australian power networks

    Science.gov (United States)

    Marshall, R. A.; Kelly, A.; Van Der Walt, T.; Honecker, A.; Ong, C.; Mikkelsen, D.; Spierings, A.; Ivanovich, G.; Yoshikawa, A.

    2017-07-01

    Geomagnetic induced currents (GICs) have been considered an issue for high-latitude power networks for some decades. More recently, GICs have been observed and studied in power networks located in lower latitude regions. This paper presents the results of a model aimed at predicting and understanding the impact of geomagnetic storms on power networks in Australia, with particular focus on the Queensland and Tasmanian networks. The model incorporates a "geoelectric field" determined using a plane wave magnetic field incident on a uniform conducting Earth, and the network model developed by Lehtinen and Pirjola (1985). Model results for two intense geomagnetic storms of solar cycle 24 are compared with transformer neutral monitors at three locations within the Queensland network and one location within the Tasmanian network. The model is then used to assess the impacts of the superintense geomagnetic storm of 29-31 October 2003 on the flow of GICs within these networks. The model results show good correlation with the observations with coefficients ranging from 0.73 to 0.96 across the observing sites. For Queensland, modeled GIC magnitudes during the superstorm of 29-31 October 2003 exceed 40 A with the larger GICs occurring in the south-east section of the network. Modeled GICs in Tasmania for the same storm do not exceed 30 A. The larger distance spans and general east-west alignment of the southern section of the Queensland network, in conjunction with some relatively low branch resistance values, result in larger modeled GICs despite Queensland being a lower latitude network than Tasmania.

  14. Double streams of protons in the distant geomagnetic tail

    International Nuclear Information System (INIS)

    Villante, U.; Lazarus, A.J.

    1975-01-01

    Two intermingled streams of protons have been observed in the distant geomagnetic tail. The number densities of the two streams are comparable, and their velocity difference tends to lie along the field direction. The lower-velocity stream is probably composed of magnetosheath protons which have diffused through the boundary of the distant tail. The higher-velocity stream appears to originate in the field reversal region

  15. Mathematical models of some geomagnetic storms with SC

    International Nuclear Information System (INIS)

    Ivanova, P.K.

    1990-01-01

    Regressive equations for H horizontal component of three geomagnetic storms with Sc:0.1.03.82, 24.01.74 and 23.03.69 -are calculated using step-by-step regression analysis. These equations relate H with parameters of solar wind and interplanetary magnetic field. Nonlinear, square, logarithmic and trigonometric dependences are considered, as well. Most essential parameters, which contribute mostly into Sc, are determined from multiplicity (46 factors) of independent parameters

  16. Geophysical fluids, geomagnetic jerks, and their impact on Earth orientation

    Czech Academy of Sciences Publication Activity Database

    Vondrák, Jan; Ron, Cyril

    2017-01-01

    Roč. 96, č. 1 (2017), s. 51-60 ISSN 0373-3742. [National Conference of Astronomers of Serbia /17./. Belgrade, 23.09.2014-27.09.2014] R&D Projects: GA ČR GA13-15943S Institutional support: RVO:67985815 Keywords : Earth orientation * geophysical fluids * geomagnetic jerks Subject RIV: DE - Earth Magnetism, Geodesy, Geography OBOR OECD: Physical geography

  17. Advances in Residential Design Related to the Influence of Geomagnetism

    Directory of Open Access Journals (Sweden)

    Francisco Glaria

    2018-02-01

    Full Text Available Since the origin of the Modern Movement, there has been a basic commitment to improving housing conditions and the well-being of occupants, especially given the prediction that 2/3 of humanity will reside in cities by 2050. Moreover, a compact model of the city with tall buildings and urban densification at this scale will be generated. Continuous constructive and technological advances have developed solid foundations on safety, energy efficiency, habitability, and sustainability in housing design. However, studies on improving the quality of life in these areas continue to be a challenge for architects and engineers. This paper seeks to contribute health-related information to the study of residential design, specifically the influence of the geomagnetic field on its occupants. After compiling information on the effects of geomagnetic fields from different medical studies over 23 years, a case study of a 16-story high-rise building is presented, with the goal of proposing architectural design recommendations for long-term occupation in the same place. The purpose of the present work is three-fold: first, to characterize the geomagnetic field variability of buildings; second, to identify the causes and possible related mechanisms; and third, to define architectural criteria on the arrangement of uses and constructive elements for housing.

  18. Archaeomagnetic Dating in Europe Using a Global Geomagnetic Field Model

    Science.gov (United States)

    Lodge, A.; Suttie, N.; Holme, R.; Shaw, J.; Hill, M. J.; Linford, P.

    2009-12-01

    Using up-to-date archaeomagnetic data from Europe and CALS7K.2 as an apriori model, we produce a global geomagnetic field model to be used for archaeomagnetic dating in Europe. More details on the modelling process will be presented elsewhere (in session GP12, abstract: Geophysical insights from archaeomagnetic dating). Here we apply the global geomagnetic field model to a series of test cases from both recently published data and unpublished data to demonstrate its application to archaeomagnetic dating. We compare the results produced using our model with those from the spherical cap harmonic model, SCHA.DIF.3K (Pavón-Carrasco et al., 2009), the global geomagnetic field model, ARCH3K.1 (Korte et al., 2009) and those produced using the palaeosecular variation curves generated using Bayesian statistics (Lanos, 2004). We include examples which emphasise the importance of using three component data (declination, inclination and intensity) to produce an improved archaeomagnetic date. In addition to the careful selection of an appropriate model for archaeomagnetic dating, the choice of errors on the model curves is vital for providing archaeologists with an age range of possible dates. We discuss how best to constrain the errors on the model curves and alternative ways to the mathematical method of Lanos (2004) for producing an archaeomagnetic date for archaeologists.

  19. Advances in Residential Design Related to the Influence of Geomagnetism

    Science.gov (United States)

    Arnedo, Israel; Sánchez-Ostiz, Ana

    2018-01-01

    Since the origin of the Modern Movement, there has been a basic commitment to improving housing conditions and the well-being of occupants, especially given the prediction that 2/3 of humanity will reside in cities by 2050. Moreover, a compact model of the city with tall buildings and urban densification at this scale will be generated. Continuous constructive and technological advances have developed solid foundations on safety, energy efficiency, habitability, and sustainability in housing design. However, studies on improving the quality of life in these areas continue to be a challenge for architects and engineers. This paper seeks to contribute health-related information to the study of residential design, specifically the influence of the geomagnetic field on its occupants. After compiling information on the effects of geomagnetic fields from different medical studies over 23 years, a case study of a 16-story high-rise building is presented, with the goal of proposing architectural design recommendations for long-term occupation in the same place. The purpose of the present work is three-fold: first, to characterize the geomagnetic field variability of buildings; second, to identify the causes and possible related mechanisms; and third, to define architectural criteria on the arrangement of uses and constructive elements for housing. PMID:29473902

  20. A global geomagnetic model based on historical and paleomagnetic data

    Science.gov (United States)

    Arneitz, P.; Leonhardt, R.; Fabian, K.

    2015-12-01

    Two main types of data are available to reconstruct the temporal and spatial geomagnetic field evolution. Historical instrumental measurements (direct data) extend from present day to the late Middle Age, and, prior the 19th century, consist mainly of declination values. Further back in the past, field reconstructions rely exclusively on the magnetization acquired by archaeological artefacts and rocks or sediments (indirect data). The major challenges for a reliable inversion approach are the inhomogeneous data distribution, the highly variable data quality, and inconsistent quality parameters. Available historical, archeomagnetic and volcanic records have been integrated into a single database together with corresponding metadata. This combination of compilations enables a joint evaluation of geomagnetic field records from different origins. In particular, data reliability and quality of indirect records are investigated using a detailed comparison with their direct counterparts. The collection forms the basis for combined inverse modeling of the geomagnetic field evolution. The iterative Bayesian inversion approach targets the implementation of reliable error treatments, which allow to combine data from different sources. Furthermore, a verification method scrutinizing the limitations of the applied inversion scheme and the used datasets is developed. Here, we will present strategies for the integration of different data types into the modeling procedure. The obtained modeling results and their validity will be discussed.

  1. Up-to-date Geomagnetic Coordinate Transforms with AACGM

    Science.gov (United States)

    Stephens, G. K.; Morrison, D.; Barnes, R. J.; Potter, M.; Schaefer, R. K.

    2017-12-01

    Geomagnetic plasmas organize along magnetic field lines, thus, it is often appropriate to use magnetic field line conjunctions for comparisons between spacecraft observations. Due to the expense of tracing magnetic field lines, the Altitude-Adjusted Corrected GeoMagnetic (AACGM) coordinate system is used. The (AACGM) coordinates are defined by the best fit dipole of the Earth's magnetic field and have been a standard tool used by the SPA community for a long time. However, standard 5 year updated coefficients for this transform are no longer available after the 2010 set. A new version of AACGM (V2 - Shepard, 2014) has been defined. AACGM V2 is fit to a spherical harmonic expansion. A pitfall with this V2 coordinate system is that it is undefined near the magnetic equator, which is problematic for determining conjunctions for spacecraft that with ground stations that pass through these regions. We have derived a new set of coefficients valid for the current epoch that allow us to continue to use the original version of AACGM. We also explore the errors that are introduced by ignoring the magnetic field caused by magnetospheric electric currents. The derived coefficients are made available to the public along with Java software that can be used to evaluate the AACGM coordinates. Shepard, S., 2014, Altitude-Adjusted Corrected Geomagnetic Coordinates: Definition and Functional Approximations, Jour. Geophys. Res., 119, 020264, DOI:10.1002/2014JA020264

  2. Long-term biases in geomagnetic K and aa indices

    Science.gov (United States)

    Love, J.J.

    2011-01-01

    Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0-2009.0, solar cycles 11-23. The K data show persistent biases, especially for high (low) K-activity levels at British (Australian) observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4. ?? 2011 Author(s).

  3. Remagnetization of lava flows spanning the last geomagnetic reversal

    Science.gov (United States)

    Vella, Jérôme; Carlut, Julie; Valet, Jean-Pierre; Goff, Maxime Le; Soler, Vicente; Lopes, Fernando

    2017-08-01

    Large directional changes of remanent magnetization within lava flows that cooled during geomagnetic reversals have been reported in several studies. A geomagnetic scenario implies extremely rapid geomagnetic changes of several degrees per day, thus difficult to reconcile with the rate of the earth's core liquid motions. So far, no complete rock magnetic model provides a clear explanation. We revisited lava flows sandwiched between an underlying reverse and an overlying normal polarity flow marking the last reversal in three distinct volcanic sequences of the La Palma Island (Canary archipelago, Spain) that are characterized by a gradual evolution of the direction of their remanent magnetization from bottom to top. Cleaning efficiency of thermal demagnetization was not improved by very rapid heating and cooling rates as well as by continuous demagnetization using a Triaxe magnetometer. We did not observe partial self-reversals and minor changes in magnetic grain sizes are not related to the within-flow directional changes. Microscopic observations indicate poor exsolution, which suggests post-cooling thermochemical remagnetization processes. This scenario is strongly reinforced by laboratory experiments that show large resistance to thermal demagnetization when thermoremanence was acquired over a long time period. We speculate that in the present situation exsolution was reactivated during in field reheating and yielded formation of new magnetite, yet magnetic domain state rearrangements could also play a role. Initial reheating when the overlying flow took place, albeit moderate (less than 200-300 °C), was enough to produce overlying components with significantly higher unblocking temperatures.

  4. Long-term biases in geomagnetic K and aa indices

    Directory of Open Access Journals (Sweden)

    J. J. Love

    2011-08-01

    Full Text Available Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0–2009.0, solar cycles 11–23. The K data show persistent biases, especially for high (low K-activity levels at British (Australian observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4.

  5. A first generation numerical geomagnetic storm prediction scheme

    International Nuclear Information System (INIS)

    Akasofu, S.-I.; Fry, C.F.

    1986-01-01

    Because geomagnetic and auroral disturbances cause significant interference on many electrical systems, it is essential to develop a reliable geomagnetic and auroral storm prediction scheme. A first generation numerical prediction scheme has been developed. The scheme consists of two major computer codes which in turn consist of a large number of subroutine codes and of empirical relationships. First of all, when a solar flare occurs, six flare parameters are determined as the input data set for the first code which is devised to show the simulated propagation of solar wind disturbances in the heliosphere to a distance of 2 a.u. Thus, one can determine the relative location of the propagating disturbances with the Earth's position. The solar wind speed and the three interplanetary magnetic field (IMF) components are then computed as a function of time at the Earth's location or any other desired (space probe) locations. These quantities in turn become the input parameters for the second major code which computes first the power of the solar wind-magnetosphere dynamo as a function of time. The power thus obtained and the three IMF components can be used to compute or infer: the predicted geometry of the auroral oval; the cross-polar cap potential; the two geomagnetic indices AE and Dst; the total energy injection rate into the polar ionosphere; and the atmospheric temperature, etc. (author)

  6. Geomagnetic storm forecasting service StormFocus: 5 years online

    Science.gov (United States)

    Podladchikova, Tatiana; Petrukovich, Anatoly; Yermolaev, Yuri

    2018-04-01

    Forecasting geomagnetic storms is highly important for many space weather applications. In this study, we review performance of the geomagnetic storm forecasting service StormFocus during 2011-2016. The service was implemented in 2011 at SpaceWeather.Ru and predicts the expected strength of geomagnetic storms as measured by Dst index several hours ahead. The forecast is based on L1 solar wind and IMF measurements and is updated every hour. The solar maximum of cycle 24 is weak, so most of the statistics are on rather moderate storms. We verify quality of selection criteria, as well as reliability of real-time input data in comparison with the final values, available in archives. In real-time operation 87% of storms were correctly predicted while the reanalysis running on final OMNI data predicts successfully 97% of storms. Thus the main reasons for prediction errors are discrepancies between real-time and final data (Dst, solar wind and IMF) due to processing errors, specifics of datasets.

  7. Drift mechanism for energetic charged particles at shocks

    International Nuclear Information System (INIS)

    Webb, G.M.; Axford, W.I.; Terasawa, T.

    1983-01-01

    The energy changes of energetic charged particles at a plane shock due to the so-called drift mechanism are analyzed by using the ''adiabatic treatment.'' The analysis shows that for a fast MHD shock, particles lose energy owing to acceleration (curvature) drift in the magnetic field at the shock with the drift velocity being antiparallel to the electric field, and they gain energy owing to gradient drift parallel to the electric field. It is shown that particles with pitch angles aligned along the magnetic field which pass through the shock tend to lose energy owing to acceleration drift, whereas particles with pitch angles nonaligned to the magnetic field gain energy owing to gradient drift. Particles that are reflected by the shock always gain energy. Slow-mode shocks may be similarly analyzed, but in this case curvature drifts give rise to particle energy gains, and gradient drifts result in particle energy losses

  8. Barber's Point, Oahu, Hawaii Drift Card Study 2002-2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drift cards were be released from Barber's Point, Oahu, approximately once a month during the two year span to get an idea of the distribution of card drift under...

  9. Electromagnetic drift modes in an inhomogeneous electron gas

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    A pair of nonlinear equations is derived which describes the dynamics of the electromagnetic drift oscillations in a nonuniform magnetized electron gas. It is shown that the nonlinear electromagnetic drift modes can propagate in the form of dipole vortices...

  10. A drift chamber constructed of aluminized mylar tubes

    International Nuclear Information System (INIS)

    Baringer, P.; Jung, C.; Ogren, H.O.; Rust, D.R.

    1987-01-01

    A thin reliable drift chamber has been constructed to be used near the interaction point of the PEP storage ring in the HRS detector. It is composed of individual drift tubes with aluminized mylar walls. (orig.)

  11. A drift chamber constructed of aluminized mylar tubes

    Science.gov (United States)

    Baringer, P.; Jung, C.; Ogren, H. O.; Rust, D. R.

    1987-03-01

    A thin reliable drift chamber has been constructed to be used near the interaction point of the PEP storage ring in the HRS detector. It is composed of individual drift tubes with aluminized mylar walls.

  12. The Development of Models for Assessment of the Geomagnetically Induced Currents Impact on Electric Power Grids during Geomagnetic Storms

    Directory of Open Access Journals (Sweden)

    VAKHNINA, V. V.

    2015-02-01

    Full Text Available A model and an algorithm for the calculation of the functioning of an electric power grid of arbitrary configuration and complexity during geomagnetic storms were developed. The calculations were performed in the MATLAB mathematical package and the Simulink environment. The binding of objects to geographical coordinates is realized in the model, which enables to determine the matrix of potentials of geoelectric fields in nodal points. In order to define the instantaneous magnetizing currents, the power transformers are designed on the basis of the T-shaped equivalent circuit with a nonlinear mutual inductance of magnetization branch. Calculation of RMS values of active, reactive and total power values in all the elements is done with regard to the impact of harmonic components of the current and voltage. The results of modeling of the impact of geomagnetic storms of various intensity with the west-east direction of the geoelectric field vector for Samara region electric power grid are given.

  13. Drift-Scale THC Seepage Model

    Energy Technology Data Exchange (ETDEWEB)

    C.R. Bryan

    2005-02-17

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral

  14. Drift-Scale THC Seepage Model

    International Nuclear Information System (INIS)

    C.R. Bryan

    2005-01-01

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral alteration on flow in rocks surrounding drifts. The DST THC submodel uses a drift

  15. The geomagnetic field - An explanation for the microturbulence in coaxial gun plasmas

    Science.gov (United States)

    Mather, J. W.; Ahluwalia, H. S.

    1988-01-01

    The complexity introduced by the geomagnetic field in several regions of a coaxial gun plasma device is described. It is shown that the annihilation of the swept-up geomagnetic flux, trapped within the highly compressed turbulent plasma, provides an explanation for varied performance and experimental results. The results indicate that the device should be aligned along the direction of the local geomagnetic field or enclosed in a mu-metal shield.

  16. Shannon information of the geomagnetic field for the past 7000 years

    OpenAIRE

    De Santis, A.; Qamili, E.

    2010-01-01

    The present behaviour of the geomagnetic field as expressed by the International Geomagnetic Reference Field (IGRF) deserves special attention when compared with that shown over the past few thousands of years by two paleomagnetic/archeomagnetic models, CALS3K and CALS7K. The application of the Information theory in terms of Shannon Information and K-entropy to these models shows characteristics of an instable geomagnetic field. Although the result is mitigated when we correct the CALS7K mode...

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

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2000-01-01

    Geomagnetic quiet days and magnetic storms are naturally believed to be due to very different solar wind conditions. In this study we however demonstrate that the long-term variation of geomagnetic quiet and disturbed days are surprisingly similar. By the use of daily averages of the geomagnetic.......7. The results indicate that the longterm,increase is due to an increase in the background solar wind parameters, rather than in the number of solar wind disturbances....

  18. Ocean modelling aspects for drift applications

    Science.gov (United States)

    Stephane, L.; Pierre, D.

    2010-12-01

    Nowadays, many authorities in charge of rescue-at-sea operations lean on operational oceanography products to outline research perimeters. Moreover, current fields estimated with sophisticated ocean forecasting systems can be used as input data for oil spill/ adrift object fate models. This emphasises the necessity of an accurate sea state forecast, with a mastered level of reliability. This work focuses on several problems inherent to drift modeling, dealing in the first place with the efficiency of the oceanic current field representation. As we want to discriminate the relevance of a particular physical process or modeling option, the idea is to generate series of current fields of different characteristics and then qualify them in term of drift prediction efficiency. Benchmarked drift scenarios were set up from real surface drifters data, collected in the Mediterranean sea and off the coasts of Angola. The time and space scales that we are interested in are about 72 hr forecasts (typical timescale communicated in case of crisis), for distance errors that we hope about a few dozen of km around the forecast (acceptable for reconnaissance by aircrafts) For the ocean prediction, we used some regional oceanic configurations based on the NEMO 2.3 code, nested into Mercator 1/12° operational system. Drift forecasts were computed offline with Mothy (Météo France oil spill modeling system) and Ariane (B. Blanke, 1997), a Lagrangian diagnostic tool. We were particularly interested in the importance of the horizontal resolution, vertical mixing schemes, and any processes that may impact the surface layer. The aim of the study is to ultimately point at the most suitable set of parameters for drift forecast use inside operational oceanic systems. We are also motivated in assessing the relevancy of ensemble forecasts regarding determinist predictions. Several tests showed that mis-described observed trajectories can finally be modelled statistically by using uncertainties

  19. Longevity of Emplacement Drift Ground Support Materials

    International Nuclear Information System (INIS)

    D.H.Tang

    2001-01-01

    The purpose of this analysis is to evaluate the factors affecting the longevity of emplacement drift ground support materials and to develop a basis for the selection of materials for ground support that will function throughout the preclosure period of a potential repository at Yucca Mountain. REV 01 ICN 01 of this analysis is developed in accordance with AP-3.10Q, Analyses and Models, Revision 2, ICN 4, and prepared in accordance with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M and O 2001a). The objective of this analysis is to update the previous analysis (CRWMS M and O 2000a) to account for related changes in the Ground Control System Description Document (CRWMS M and O 2000b), the Monitored Geologic Repository Project Description Document, which is included in the Requirements and Criteria for Implementing a Repository Design that can be Operated Over a Range of Thermal Modes (BSC 2001), input information, and in environmental conditions, and to provide updated information on candidate ground support materials. Candidate materials for ground support are carbon steel and cement grout. Steel is mainly used for steel sets, lagging, channel, rock bolts, and wire mesh. Cement grout is only considered in the case of grouted rock bolts. Candidate materials for the emplacement drift invert are carbon steel and granular natural material. Materials are evaluated for the repository emplacement drift environment based on the updated thermal loading condition and waste package design. The analysis consists of the following tasks: (1) Identify factors affecting the longevity of ground support materials for use in emplacement drifts. (2) Review existing documents concerning the behavior of candidate ground support materials during the preclosure period. (3) Evaluate impacts of temperature and radiation effects on mechanical and thermal properties of steel. Assess corrosion potential of steel at emplacement drift environment. (4

  20. Analysis of Geomagnetic Field Variations during Total Solar Eclipses Using INTERMAGNET Data

    Science.gov (United States)

    KIM, J. H.; Chang, H. Y.

    2017-12-01

    We investigate variations of the geomagnetic field observed by INTERMAGNET geomagnetic observatories over which the totality path passed during a solar eclipse. We compare results acquired by 6 geomagnetic observatories during the 4 total solar eclipses (11 August 1999, 1 August 2008, 11 July 2010, and 20 March 2015) in terms of geomagnetic and solar ecliptic parameters. These total solar eclipses are the only total solar eclipse during which the umbra of the moon swept an INTERMAGNET geomagnetic observatory and simultaneously variations of the geomagnetic field are recorded. We have confirmed previous studies that increase BY and decreases of BX, BZ and F are conspicuous. Interestingly, we have noted that variations of geomagnetic field components observed during the total solar eclipse at Isla de Pascua Mataveri (Easter Island) in Chile (IPM) in the southern hemisphere show distinct decrease of BY and increases of BX and BZ on the contrary. We have found, however, that variations of BX, BY, BZ and F observed at Hornsund in Norway (HRN) seem to be dominated by other geomagnetic occurrence. In addition, we have attempted to obtain any signatures of influence on the temporal behavior of the variation in the geomagnetic field signal during the solar eclipse by employing the wavelet analysis technique. Finally, we conclude by pointing out that despite apparent success a more sophisticate and reliable algorithm is required before implementing to make quantitative comparisons.

  1. Worldwide Magnetograms with Geomagnetic Components D, H, Z, or X, Y, and Z

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) receives magnetograms from over 200 geomagnetic observatories....

  2. Parametric decay of lower hybrid wave into drift waves

    International Nuclear Information System (INIS)

    Sanuki, Heiji.

    1976-12-01

    A dispersion relation describing the parametric decay of a lower hybrid wave into an electrostatic drift wave and a drift Alfven wave is derived for an inhomogeneous magnetized plasma. Particularly the stimulated scattering of a drift Alfven wave in such a plasma was investigated in detail. The resonance backscattering instability is found to yield the minimum threshold. (auth.)

  3. Modeling the Magnetopause Shadowing and Drift Orbit Bifurcation Loss during the June 2015 Dropout Event

    Science.gov (United States)

    Tu, W.; Cunningham, G.

    2017-12-01

    The relativistic electron flux in Earth's radiation belt are observed to drop by orders of magnitude on timescale of a few hours. Where do the electrons go during the dropout? This is one of the most important outstanding questions in radiation belt studies. Here we will study the 22 June 2015 dropout event which occurred during one of the largest geomagnetic storms in the last decade. A sudden and nearly complete loss of all the outer zone relativistic and ultra-relativistic electrons were observed after a strong interplanetary shock. The Last Closed Drift Shell (LCDS) calculated using the TS04 model reached as low as L*=3.7 during the shock and stay below L*=4 for 1 hour. The unusually low LCDS values suggest that magnetopause shadowing and the associated outward radial diffusion can contribute significantly to the observed dropout. In addition, Drift Orbit Bifurcation (DOB) has been suggested as an important loss mechanism for radiation belt electrons, especially when the solar wind dynamic pressure is high, but its relative importance has not been quantified. Here, we will model the June 2015 dropout event using a radial diffusion model that includes physical and event-specific inputs. First, we will trace electron drift shells based on TS04 model to identify the LCDS and bifurcation regions as a function of the 2nd adiabatic invariant (K) and time. To model magnetopause shadowing, electron lifetimes in our model will be set to electron drift periods at L*>LCDS. Electron lifetimes inside the bifurcation region have been estimated by Ukhorskiy et al. [JGR 2011, doi:10.1029/2011JA016623] as a function of L* and K, which will also be implemented in the model. This will be the first effort to include the DOB loss in a comprehensive radiation belt model. Furthermore, to realistically simulate outward radial diffusion, the new radial diffusion coefficients that are calculated based on the realistic TS04 model and include physical K dependence [Cunningham, JGR 2016

  4. Passive appendages generate drift through symmetry breaking

    Science.gov (United States)

    Lācis, U.; Brosse, N.; Ingremeau, F.; Mazzino, A.; Lundell, F.; Kellay, H.; Bagheri, S.

    2014-10-01

    Plants and animals use plumes, barbs, tails, feathers, hairs and fins to aid locomotion. Many of these appendages are not actively controlled, instead they have to interact passively with the surrounding fluid to generate motion. Here, we use theory, experiments and numerical simulations to show that an object with a protrusion in a separated flow drifts sideways by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in a fluid flow is unstable and how it stabilizes either to the left or right of the incoming flow direction. It is plausible that organisms with appendages in a separated flow use this newly discovered mechanism for locomotion; examples include the drift of plumed seeds without wind and the passive reorientation of motile animals.

  5. Hole drift mobility in poly(hexylphenylsilane)

    International Nuclear Information System (INIS)

    Kunimi, Y.; Seki, S.; Tagawa, S.

    2000-01-01

    Poly(n-alkylphenylsilane)s in which n-alkyl were changed from methyl to octyl were polymerized. Hole transport properties of poly(alkyllphenylsilane)s were systematically studied by the DC time-of-flight (TOF) technique. While the hole drift mobility of poly(methylphenylsilane) increased monotonously in entire field, those of poly(hexylphenylsilane) and poly(octylphenylsilane) decreased with increase in the field strength. Temperature dependence of hole drift mobility in those polymers was small. On the basis of Baessler's disorder formalism the mobility was analyzed quantitatively to disserve complex contributions of charge transport. The analyzed results indicated that with increase in the length of n-alkyl side-groups, the energetic disorder of hopping sites became smaller and the disorder of distance between hopping sites became larger. These results were supported by the results obtained by UV absorption measurement and positron annihilation life-time spectroscopy measurement. (author)

  6. Electromagnetic nonlinear gyrokinetics with polarization drift

    International Nuclear Information System (INIS)

    Duthoit, F.-X.; Hahm, T. S.; Wang, Lu

    2014-01-01

    A set of new nonlinear electromagnetic gyrokinetic Vlasov equation with polarization drift and gyrokinetic Maxwell equations is systematically derived by using the Lie-transform perturbation method in toroidal geometry. For the first time, we recover the drift-kinetic expression for parallel acceleration [R. M. Kulsrud, in Basic Plasma Physics, edited by A. A. Galeev and R. N. Sudan (North-Holland, Amsterdam, 1983)] from the nonlinear gyrokinetic equations, thereby bridging a gap between the two formulations. This formalism should be useful in addressing nonlinear ion Compton scattering of intermediate-mode-number toroidal Alfvén eigenmodes for which the polarization current nonlinearity [T. S. Hahm and L. Chen, Phys. Rev. Lett. 74, 266 (1995)] and the usual finite Larmor radius effects should compete

  7. Clean industrial room for drift tube assembling

    International Nuclear Information System (INIS)

    Glonti, G.L.; Gongadze, A.L.; Evtukhovich, P.G.

    2001-01-01

    Description of a clean industrial room for assembly of drift tubes for the muon spectrometer of the ATLAS experiment is presented. High quality specifications on the detectors to be produced demanded creation of a workplace with stable temperature and humidity, as well as minimum quantity of dust in the room. Checking of parameters of intra-room air during long period of continuous work has confirmed correctness of the designed characteristics of the climatic system installed in the clean room. The room large volume (∼ 190 m 3 ), the powerful and flexible climatic system, and simplicity of service allow assembling of detectors with length up to 5 m. Subsequent checking of functionality of the assembled detectors has shown high quality of assembling (the amount of rejected tubes does not exceed 2%). It demonstrates conformity to the assembling quality requirements for mass production of drift chambers for the muon spectrometer. (author)

  8. Clean Industrial Room for Drift Tube Assembling

    CERN Document Server

    Glonti, GL; Evtoukhovitch, P G; Kroa, G; Manz, A; Potrap, I N; Rihter, P; Stoletov, G D; Tskhadadze, E G; Chepurnov, V F; Chirkov, A V; Shelkov, G A

    2001-01-01

    Description of a clean industrial room for assembly of drift tubes for the muon spectrometer of the ATLAS experiment is presented. High quality specifications on the detectors to be produced demanded creation of a workplace with stable temperature and humidity, as well as minimum quantity of dust in the room. Checking of parameters of intra-room air during long period of continuous work has been confirmed correctness of the designed characteristics of the climatic system installed in the clean room. The room large volum (\\sim 190 m^3), the powerful and flexible climatic system, and simplicity of service allow assembling of detectors with length up to 5 m. Subsequent checking of functionality of the assembled detectors has shown high quality of assembling (the amount of rejected tubes does not exceed 2 %). It demonstrates conformity to the assembling quality requirements for mass production of drift chambers for the muon spectrometer.

  9. Toroidal effects on drift wave turbulence

    Energy Technology Data Exchange (ETDEWEB)

    LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.

    1992-09-23

    The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling.

  10. Bottle appeal drifts across the Pacific

    Science.gov (United States)

    Ebbesmeyer, Curtis; Ingraham, W. James, Jr.; McKinnon, Richard; Okubo, Akira; Wang, Dong-Ping; Strickland, Richard; Willing, Peter

    Pacific drift currents were used by a group of oceanographers to estimate the path of a drift bottle that was found on a beach of Barkley Sound in Vancouver Island by Richard Strickland on June 10, 1990. The Chinese rice wine bottle, which remained unopened until December 18, 1991, contained six leaflets, one appealing for the release of China's well-known dissident, Wei Jingsheng. The bottle was one of thousands set adrift as part of a propaganda effort from the islands of Quemoy and Matsu off mainland China shortly after Wei was sentenced in 1979 to 15 years in prison (see Figure 1 for locations). Wei was in poor health and still in prison when the bottle made its way across the Pacific Ocean.

  11. The drift-flux correlation package MDS

    International Nuclear Information System (INIS)

    Hoeld, A.

    2001-01-01

    Based on the SONNENBURG drift-flux correlation, developed at GRS/Garching (Germany), a comprehensive drift-flux correlation package (MDS) has been established. Its aim is to support thermal-hydraulic mixture-fluid models, models being used for the simulation of the steady state and transient behaviour of characteristic thermal-hydraulic parameters of single- or two-phase fluids flowing along coolant channels of different types (being, e.g., parts of NPP-s, steam generators etc.). The characteristic properties of this package with respect to the behaviour at co- and counter-current flow, its inverse solutions needed for steady state simulations, its behaviour when approaching the lower or upper boundary of a two-phase region, its verification and behaviour with respect to other correlations will be discussed. An adequate driver code, MDSDRI, has been established too, allowing to test the package very thoroughly out of the complex thermal-hydraulic codes. (author)

  12. Ionospheric drift measurements: Skymap points selection

    Czech Academy of Sciences Publication Activity Database

    Kouba, Daniel; Boška, Josef; Galkin, I. A.; Santolík, Ondřej; Šauli, Petra

    2008-01-01

    Roč. 43, č. 1 (2008), RS1S90/1-RS1S90/11 ISSN 0048-6604 R&D Projects: GA ČR GA205/06/1619; GA ČR GA205/06/1267; GA AV ČR IAA300420504 Grant - others:GA MŠk(CZ) OC 296; MIERS(XE) COST 296 Institutional research plan: CEZ:AV0Z30420517 Keywords : digisonde drift measurement * plasma drift * radio sounding * ionosphere * Doppler shift * skymap processing Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.092, year: 2008 http://www.agu.org/pubs/crossref/2008/2007RS003633.shtml

  13. Pulsar magnetic alignment. The drifting subpulses

    International Nuclear Information System (INIS)

    Jones, P.B.

    1977-01-01

    According to Ruderman and Sutherland (Ap.J.;196:51 (1975)) the subpulse drift observed in certain pulsars is a consequence of the circulation around the magnetic axis of electron-positron discharges occurring within an acceleration region near the polar cap. The predicted period of circulation P 3 is of the correct order of magnitude, but the sense of circulation and therefore the direction of subpulse drift is not consistent with indirect evidence, from observed integrated pulse widths, on the variation with pulsar age of the angle between the spin and magnetic axes. It is shown that this problem is resolved by a model of the acceleration electric field based on space charge limited ion flow. (author)

  14. The drift-flux correlation package MDS

    Energy Technology Data Exchange (ETDEWEB)

    Hoeld, A. [Bernaysstr. 16A, Munich, F.R. (Germany)

    2001-07-01

    Based on the SONNENBURG drift-flux correlation, developed at GRS/Garching (Germany), a comprehensive drift-flux correlation package (MDS) has been established. Its aim is to support thermal-hydraulic mixture-fluid models, models being used for the simulation of the steady state and transient behaviour of characteristic thermal-hydraulic parameters of single- or two-phase fluids flowing along coolant channels of different types (being, e.g., parts of NPP-s, steam generators etc.). The characteristic properties of this package with respect to the behaviour at co- and counter-current flow, its inverse solutions needed for steady state simulations, its behaviour when approaching the lower or upper boundary of a two-phase region, its verification and behaviour with respect to other correlations will be discussed. An adequate driver code, MDSDRI, has been established too, allowing to test the package very thoroughly out of the complex thermal-hydraulic codes. (author)

  15. Toroidal effects on drift wave turbulence

    International Nuclear Information System (INIS)

    LeBrun, M.J.; Tajima, T.; Gray, M.G.; Furnish, G.; Horton, W.

    1992-01-01

    The universal drift instability and other drift instabilities driven by density and temperature gradients in a toroidal system are investigated in both linear and nonlinear regimes via particle simulation. Runs in toroidal and cylindrical geometry show dramatic differences in plasma behavior, primarily due to the toroidicity-induced coupling of rational surfaces through the poloidal mode number m. In the toroidal system studied, the eigenmodes are seen to possess (i) an elongated, nearly global radial extent (ii) a higher growth rate than in the corresponding cylindrical system, (iii) an eigenfrequency nearly constant with radius, (iv) a global temperature relaxation and enhancement of thermal heat conduction. Most importantly, the measured Xi shows an increase with radius and an absolute value on the order of that observed in experiment. On the basis of our observations, we argue that the increase in Xi with radius observed in experiment is caused by the global nature of heat convection in the presence of toroidicity-induced mode coupling

  16. Cylindrical geometry for proportional and drift chambers

    International Nuclear Information System (INIS)

    Sadoulet, B.

    1975-06-01

    For experiments performed around storage rings such as e + e - rings or the ISR pp rings, cylindrical wire chambers are very attractive. They surround the beam pipe completely without any dead region in the azimuth, and fit well with the geometry of events where particles are more or less spherically produced. Unfortunately, cylindrical proportional or drift chambers are difficult to make. Problems are discussed and two approaches to fabricating the cathodes are discussed. (WHK)

  17. Spin-drift transport in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M Idrish [Nanoscale Science and Technology Centre and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong, Chittagong-4331 (Bangladesh)

    2008-02-07

    We present a study on spin transport in semiconductors under applied electric fields. Our experiments detect photoinjected electron spins and their relaxation during drift transport in intrinsic and moderately n-doped GaAs, based on the extraordinary Hall (eH) effect. For relatively low electric field (E), the optically spin-induced eH effect in n-doped GaAs is found to be enhanced with increasing doping density and not to depend much on E, indicating that a substantial amount of optical spin polarization is preserved during the drift transport in these extrinsic semiconductors. However, when the spin-oriented electrons are injected with a high E, a very significant decrease is observed in the eH voltage (V{sub eH}) due to an increase in the spin precession frequency of the hot electrons. Spin relaxation by the D'yakonov-Perel' mechanism is calculated, and is suggested to be the reason for such a rapid spin relaxation for hot electrons under a high E. However, in an intrinsic GaAs (i-GaAs), a much weaker V{sub eH} is observed and, as the electron spins scattered by holes due to the Coulomb interaction in i-GaAs, the spin relaxation by the Bir-Aronov-Pikus mechanism is considered. Skew scattering and side jump as possible mechanisms of the optically spin-induced transverse Hall currents are discussed. Based on a spin drift-diffusion model, drift and diffusion contributions to the V{sub eH} are examined. The results are also discussed in comparison with theoretical investigations.

  18. Unstable universal drift eigenmodes in toroidal plasmas

    International Nuclear Information System (INIS)

    Cheng, C.Z.; Chen, L.

    1979-08-01

    The eigenmode equation describing ballooning collisionless drift instabilities is analyzed both analytically and numerically. A new branch of eigenmodes, which corresponds to quasi-bound states due to the finite toroidicity, is shown to be destabilized by electron Landau damping for typical Tokamak parameters. This branch cannot be understood by the strong coupling approximation. However, the slab-like (Pearlstein-Berk type) branch is found to remain stable and experience enhanced shear damping due to finite toroidicity

  19. Snow Drift Management: Summit Station Greenland

    Science.gov (United States)

    2016-05-01

    management Snow surveys Transport analysis Winds -- Speed 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF...that about 25% of the estimated snow that the wind transports to Summit each winter is deposited and forms drifts, mostly in close proxim- ity to...the structures. This analysis demonstrates that weather data ( wind speed and direction) and a transport analysis can aid in estimating the vol- ume of

  20. New developments on silicon drift detectors

    International Nuclear Information System (INIS)

    Rashevsky, A.

    1996-01-01

    In the frame of the project to develop large-area linear drift detectors few prototypes have been designed and produced. the function of these prototypes is to allow the evaluation of the solutions chosen for the geometry of the on-board electrodes and the production process. On these prototypes it is studied the static characteristics and measured time of-flight and charge collection injecting charges with an IR laser source. It is report the results from one of the prototypes

  1. The Absence of Stokes Drift in Waves

    OpenAIRE

    Chafin, Clifford

    2015-01-01

    Stokes drift has been as central to the history of wave theory as it has been distressingly absent from experiment. Neither wave tanks nor experiments in open bodies detect this without nearly canceling "eulerian flows." Acoustic waves have an analogous problem that is particularly problematic in the vorticity production at the edges of beams. Here we demonstrate that the explanation for this arises from subtle end-of-packet and wavetrain gradient effects such as microbreaking events and wave...

  2. Continued Drift, but without the Acrimony

    DEFF Research Database (Denmark)

    Nielsen, Kristian L.

    2013-01-01

    If the measure of Barack Obama's success in mending US–European relations is whether the tone has improved, his presidency has been a great success. If the measure of success, however, is halting the drifting apart of policy preferences, the picture looks a lot less rosy. This article argues....... The Obama administration realises that, and by this more limited measure, it has succeeded brilliantly....

  3. Cathode readout with stripped resistive drift tubes

    International Nuclear Information System (INIS)

    Bychkov, V.N.; Kekelidze, G.D.; Novikov, E.A.; Peshekhonov, V.D.; Shafranov, M.D.; Zhiltsov, V.E.

    1995-01-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented. (orig.)

  4. Cathode readout with stripped resistive drift tubes

    Science.gov (United States)

    Bychkov, V. N.; Kekelidze, G. D.; Novikov, E. A.; Peshekhonov, V. D.; Shafranov, M. D.; Zhiltsov, V. E.

    1995-12-01

    A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented.

  5. Drift bifurcation detection for dissipative solitons

    International Nuclear Information System (INIS)

    Liehr, A W; Boedeker, H U; Roettger, M C; Frank, T D; Friedrich, R; Purwins, H-G

    2003-01-01

    We report on the experimental detection of a drift bifurcation for dissipative solitons, which we observe in the form of current filaments in a planar semiconductor-gas-discharge system. By introducing a new stochastic data analysis technique we find that due to a change of system parameters the dissipative solitons undergo a transition from purely noise-driven objects with Brownian motion to particles with a dynamically stabilized finite velocity

  6. Formation Mechanisms of the Spring-Autumn Asymmetry of the Midlatitudinal NmF2 under Daytime Quiet Geomagnetic Conditions at Low Solar Activity

    Science.gov (United States)

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

    2018-05-01

    Formation mechanism of the spring-autumn asymmetry of the F2-layer peak electron number density of the midlatitudinal ionosphere, NmF2, under daytime quiet geomagnetic conditions at low solar activity are studied. We used the ionospheric parameters measured by the ionosonde and incoherent scatter radar at Millstone Hill on March 3, 2007, March 29, 2007, September 12, 2007, and September 18, 1984. The altitudinal profiles of the electron density and temperature were calculated for the studied conditions using a one-dimensional, nonstationary, ionosphere-plasmasphere theoretical model for middle geomagnetic latitudes. The study has shown that there are two main factors contributing to the formation of the observed spring-autumn asymmetry of NmF2: first, the spring-autumn variations of the plasma drift along the geomagnetic field due to the corresponding variations in the components of the neutral wind velocity, and, second, the difference between the composition of the neutral atmosphere under the spring and autumn conditions at the same values of the universal time and the ionospheric F2-layer peak altitude. The seasonal variations of the rate of O+(4S) ion production, which are associated with chemical reactions with the participation of the electronically excited ions of atomic oxygen, does not significantly affect the studied NmF2 asymmetry. The difference in the degree of influence of O+(4S) ion reactions with vibrationally excited N2 and O2 on NmF2 under spring and autumn conditions does not significantly change the spring-autumn asymmetry of NmF2.

  7. Transient chaotic transport in dissipative drift motion

    Energy Technology Data Exchange (ETDEWEB)

    Oyarzabal, R.S. [Pós-Graduação em Ciências/Física, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Szezech, J.D. [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Batista, A.M., E-mail: antoniomarcosbatista@gmail.com [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Souza, S.L.T. de [Departamento de Física e Matemática, Universidade Federal de São João del Rei, 36420-000, Ouro Branco, MG (Brazil); Caldas, I.L. [Instituto de Física, Universidade de São Paulo, 05315-970, São Paulo, SP (Brazil); Viana, R.L. [Departamento de Física, Universidade Federal do Paraná, 81531-990, Curitiba, PR (Brazil); Sanjuán, M.A.F. [Departamento de Física, Universidad Rey Juan Carlos, Tulipán s/n, 28933 Móstoles, Madrid (Spain)

    2016-04-22

    Highlights: • We consider a situation for which a chaotic transient is present in the dynamics of the two-wave model with damping. • The damping in plasma models can be a way for study a realistic behavior of confinement due the collisional effect. • The escape time as a function of the damping obey a power-law scaling. • We have made a qualitative transport analysis with a simple model that can be useful for more complete models. • We have shown that the pattern of the basin of attraction depends on the damping parameter. - Abstract: We investigate chaotic particle transport in magnetised plasmas with two electrostatic drift waves. Considering dissipation in the drift motion, we verify that the removed KAM surfaces originate periodic attractors with their corresponding basins of attraction. We show that the properties of the basins depend on the dissipation and the space-averaged escape time decays exponentially when the dissipation increases. We find positive finite time Lyapunov exponents in dissipative drift motion, consequently the trajectories exhibit transient chaotic transport. These features indicate how the transient plasma transport depends on the dissipation.

  8. Longevity of Emplacement Drift Ground Support Materials

    International Nuclear Information System (INIS)

    Tang, D.

    2000-01-01

    The purpose of this analysis is to evaluate the factors affecting the longevity of emplacement drift ground support materials and to develop a basis for selection of materials for ground support that will function throughout the preclosure period. The Development Plan (DP) for this analysis is given in CRWMS M and O (Civilian Radioactive Waste Management System Management and Operating Contractor) (1999a). The candidate materials for ground support are steel (carbon steel, ductile cast iron, galvanized steel, and stainless steel, etc.) and cement. Steel will mainly be used for steel sets, lagging, channels, rock bolts, and wire mesh. Cement usage is only considered in the case of grouted rock bolts. The candidate materials for the invert structure are steel and crushed rock ballast. The materials shall be evaluated for the repository emplacement drift environment under a specific thermal loading condition based on the proposed License Application Design Selection (LADS) design. The analysis consists of the following tasks: (1) Identify factors affecting the longevity of ground control materials for use in emplacement drifts. (2) Review existing documents concerning behavior of candidate ground control materials during the preclosure period. The major criteria to be considered for steel are mechanical and thermal properties, and durability, of which corrosion is the most important concern. (3) Evaluate the available results and develop recommendations for material(s) to be used

  9. Monitored Drift Chambers in the ATLAS Detector

    CERN Multimedia

    Herten, G

    Monitored Drift Chambers (MDT) are used in the ATLAS Detector to measure the momentum of high energy muons. They consist of drift tubes, which are filled with an Ar-CO2 gas mixture at 3 bar gas pressure. About 1200 drift chambers are required for ATLAS. They are up to 6 m long. Nevertheless the position of every wire needs to be known with a precision of 20 µm within a chamber. In addition, optical alignment sensors are required to measure the relative position of adjacent chambers with a precision of 30µm. This gigantic task seems impossible at first instance. Indeed it took many years of R&D to invent the right tools and methods before the first chamber could be built according to specifications. Today, at the time when 50% of the chambers have been produced, we are confident that the goal for ATLAS can be reached. The mechanical precision of the chambers could be verified with the x-ray tomograph at CERN. This ingenious device, developed for the MDT system, is able to measure the wire position insid...

  10. Internal Clock Drift Estimation in Computer Clusters

    Directory of Open Access Journals (Sweden)

    Hicham Marouani

    2008-01-01

    Full Text Available Most computers have several high-resolution timing sources, from the programmable interrupt timer to the cycle counter. Yet, even at a precision of one cycle in ten millions, clocks may drift significantly in a single second at a clock frequency of several GHz. When tracing the low-level system events in computer clusters, such as packet sending or reception, each computer system records its own events using an internal clock. In order to properly understand the global system behavior and performance, as reported by the events recorded on each computer, it is important to estimate precisely the clock differences and drift between the different computers in the system. This article studies the clock precision and stability of several computer systems, with different architectures. It also studies the typical network delay characteristics, since time synchronization algorithms rely on the exchange of network packets and are dependent on the symmetry of the delays. A very precise clock, based on the atomic time provided by the GPS satellite network, was used as a reference to measure clock drifts and network delays. The results obtained are of immediate use to all applications which depend on computer clocks or network time synchronization accuracy.

  11. Simplified Drift Analysis for Proving Lower Bounds in Evolutionary Computation

    DEFF Research Database (Denmark)

    Oliveto, Pietro S.; Witt, Carsten

    2011-01-01

    Drift analysis is a powerful tool used to bound the optimization time of evolutionary algorithms (EAs). Various previous works apply a drift theorem going back to Hajek in order to show exponential lower bounds on the optimization time of EAs. However, this drift theorem is tedious to read...... and to apply since it requires two bounds on the moment-generating (exponential) function of the drift. A recent work identifies a specialization of this drift theorem that is much easier to apply. Nevertheless, it is not as simple and not as general as possible. The present paper picks up Hajek’s line...

  12. The Egyptian geomagnetic reference field to the Epoch, 2010.0

    Science.gov (United States)

    Deebes, H. A.; Abd Elaal, E. M.; Arafa, T.; Lethy, A.; El Emam, A.; Ghamry, E.; Odah, H.

    2017-06-01

    The present work is a compilation of two tasks within the frame of the project ;Geomagnetic Survey & Detailed Geomagnetic Measurements within the Egyptian Territory; funded by the ;Science and Technology Development Fund agency (STDF);. The National Research Institute of Astronomy and Geophysics (NRIAG), has conducted a new extensive land geomagnetic survey that covers the whole Egyptian territory. The field measurements have been done at 3212 points along all the asphalted roads, defined tracks, and ill-defined tracks in Egypt; with total length of 11,586 km. In the present work, the measurements cover for the first time new areas as: the southern eastern borders of Egypt including Halayeb and Shlatin, the Quattara depresion in the western desert, and the new roads between Farafra and Baharia oasis. Also marine geomagnetic survey have been applied for the first time in Naser lake. Misallat and Abu-Simble geomagnetic observatories have been used to reduce the field data to the Epoch 2010. During the field measurements, whenever possible, the old stations occupied by the previous observers have been re-occupied to determine the secular variations at these points. The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF) and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF) 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF) 2010 is indicated.

  13. Coronal mass ejections and disturbances in solar wind plasma parameters in relation with geomagnetic storms

    International Nuclear Information System (INIS)

    Verma, P L; Singh, Puspraj; Singh, Preetam

    2014-01-01

    Coronal Mass Ejections (CMEs) are the drastic solar events in which huge amount of solar plasma materials are ejected into the heliosphere from the sun and are mainly responsible to generate large disturbances in solar wind plasma parameters and geomagnetic storms in geomagnetic field. We have studied geomagnetic storms, (Dst ≤-75 nT) observed during the period of 1997-2007 with Coronal Mass Ejections and disturbances in solar wind plasma parameters (solar wind temperature, velocity, density and interplanetary magnetic field) .We have inferred that most of the geomagnetic storms are associated with halo and partial halo Coronal Mass Ejections (CMEs).The association rate of halo and partial halo coronal mass ejections are found 72.37 % and 27.63 % respectively. Further we have concluded that geomagnetic storms are closely associated with the disturbances in solar wind plasma parameters. We have determined positive co-relation between magnitudes of geomagnetic storms and magnitude of jump in solar wind plasma temperature, jump in solar wind plasma density, jump in solar wind plasma velocity and jump in average interplanetary magnetic field with co-relation co-efficient 0 .35 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma temperature, 0.19 between magnitude of geomagnetic storms and magnitude of jump in solar wind density, 0.34 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma velocity, 0.66 between magnitude of geomagnetic storms and magnitude of jump in average interplanetary magnetic field respectively. We have concluded that geomagnetic storms are mainly caused by Coronal Mass Ejections and disturbances in solar wind plasma parameters that they generate.

  14. Abstraction of Drift-Scale Coupled Processes

    International Nuclear Information System (INIS)

    Francis, N.D.; Sassani, D.

    2000-01-01

    This Analysis/Model Report (AMR) describes an abstraction, for the performance assessment total system model, of the near-field host rock water chemistry and gas-phase composition. It also provides an abstracted process model analysis of potentially important differences in the thermal hydrologic (TH) variables used to describe the performance of a geologic repository obtained from models that include fully coupled reactive transport with thermal hydrology and those that include thermal hydrology alone. Specifically, the motivation of the process-level model comparison between fully coupled thermal-hydrologic-chemical (THC) and thermal-hydrologic-only (TH-only) is to provide the necessary justification as to why the in-drift thermodynamic environment and the near-field host rock percolation flux, the essential TH variables used to describe the performance of a geologic repository, can be obtained using a TH-only model and applied directly into a TSPA abstraction without recourse to a fully coupled reactive transport model. Abstraction as used in the context of this AMR refers to an extraction of essential data or information from the process-level model. The abstraction analysis reproduces and bounds the results of the underlying detailed process-level model. The primary purpose of this AMR is to abstract the results of the fully-coupled, THC model (CRWMS M andO 2000a) for effects on water and gas-phase composition adjacent to the drift wall (in the near-field host rock). It is assumed that drift wall fracture water and gas compositions may enter the emplacement drift before, during, and after the heating period. The heating period includes both the preclosure, in which the repository drifts are ventilated, and the postclosure periods, with backfill and drip shield emplacement at the time of repository closure. Although the preclosure period (50 years) is included in the process models, the postclosure performance assessment starts at the end of this initial period

  15. Ground Control for Emplacement Drifts for SR

    International Nuclear Information System (INIS)

    Y. Sun

    2000-01-01

    This analysis demonstrates that a satisfactory ground control system can be designed for the Yucca Mountain site, and provides the technical basis for the design of ground support systems to be used in repository emplacement and non-emplacement drifts. The repository ground support design was based on analytical methods using acquired computer codes, and focused on the final support systems. A literature review of case histories, including the lessons learned from the design and construction of the ESF, the studies on the seismic damages of underground openings, and the use of rock mass classification systems in the ground support design, was conducted (Sections 6.3.4 and 6.4). This review provided some basis for determining the inputs and methodologies used in this analysis. Stability of the supported and unsupported emplacement and non-emplacement drifts was evaluated in this analysis. The excavation effects (i.e., state of the stress change due to excavation), thermal effects (i.e., due to heat output from waste packages), and seismic effects (i.e., from potential earthquake events) were evaluated, and stress controlled modes of failure were examined for two in situ stress conditions (k 0 =0.3 and 1.0) using rock properties representing rock mass categories of 1 and 5. Variation of rock mass units such as the non-lithophysal (Tptpmn) and lithophysal (Tptpll) was considered in the analysis. The focus was on the non-lithophysal unit because this unit appears to be relatively weaker and has much smaller joint spacing. Therefore, the drift stability and ground support needs were considered to be controlled by the design for this rock unit. The ground support systems for both emplacement and non-emplacement drifts were incorporated into the models to assess their performance under in situ, thermal, and seismic loading conditions. Both continuum and discontinuum modeling approaches were employed in the analyses of the rock mass behavior and in the evaluation of the

  16. In-Drift Precipitates/Salts Analysis

    International Nuclear Information System (INIS)

    Mariner, P.

    2001-01-01

    As directed by a written development plan (CRWMS M and O 1999a), an analysis of the effects of salts and precipitates on the repository chemical environment is to be developed and documented in an Analyses/Model Report (AMR). The purpose of this analysis is to assist Performance Assessment Operations (PAO) and the Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). The purpose of this ICN is to qualify and document qualification of the AMR's technical products. The scope of this document is to develop a model of the processes that govern salt precipitation and dissolution and resulting water composition in the Engineered Barrier System (EBS). This model is developed to serve as a basis for the in-drift geochemical modeling work performed by PAO and is to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. However, the concepts may also apply to some near and far field geochemical processes and can have conceptual application within the unsaturated zone and saturated zone transport modeling efforts. The intended use of the model developed in this report is to estimate, within an appropriate level of confidence, the pH, chloride concentration, and ionic strength of water on the drip shield or other location within the drift during the post-closure period. These estimates are based on evaporative processes that are subject to a broad range of potential environmental conditions and are independent of the presence or absence of backfill. An additional intended use is to estimate the environmental conditions required for complete vaporization of water. The presence and composition of liquid water

  17. In-Drift Precipitates/Salts Analysis

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2001-01-10

    As directed by a written development plan (CRWMS M&O 1999a), an analysis of the effects of salts and precipitates on the repository chemical environment is to be developed and documented in an Analyses/Model Report (AMR). The purpose of this analysis is to assist Performance Assessment Operations (PAO) and the Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). The purpose of this ICN is to qualify and document qualification of the AMR's technical products. The scope of this document is to develop a model of the processes that govern salt precipitation and dissolution and resulting water composition in the Engineered Barrier System (EBS). This model is developed to serve as a basis for the in-drift geochemical modeling work performed by PAO and is to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. However, the concepts may also apply to some near and far field geochemical processes and can have conceptual application within the unsaturated zone and saturated zone transport modeling efforts. The intended use of the model developed in this report is to estimate, within an appropriate level of confidence, the pH, chloride concentration, and ionic strength of water on the drip shield or other location within the drift during the post-closure period. These estimates are based on evaporative processes that are subject to a broad range of potential environmental conditions and are independent of the presence or absence of backfill. An additional intended use is to estimate the environmental conditions required for complete vaporization of water. The presence and composition of liquid water

  18. A novel silicon drift detector with two dimensional drift time measurement

    International Nuclear Information System (INIS)

    Hijzen, E.A.; Schooneveld, E.M.; Van Eijk, C.W.E.; Hollander, R.W.; Sarro, P.M.; Van den Bogaard, A.

    1994-01-01

    Until now silicon drift detectors with two dimensional position resolution made use of drift time measurement in one dimension only. The resolution in the other dimension was obtained by dividing the collecting anode into small pixels. In this paper we present a new type of drift detector that uses drift time measurements for both dimensions. The design consists of concentric quadrilateral closed strips with a small collecting anode in the centre. At first electrons will travel perpendicular to the strips until they reach a diagonal. Then they will proceed along this diagonal until they are collected at the centre. Position resolution in two dimensions can be obtained when both the time the electrons need to reach the diagonal and the time they need to reach the centre are measured. The latter is obtained from the collecting anode, the former from a diagonal strip present at the back side of the detector. Compared to common 2D drift detectors this detector offers the advantage of a small amount of readout electronics. It also has the advantage of having just one small collecting anode with a very low capacitance, resulting in low noise and therefore in a good energy resolution. ((orig.))

  19. Theoretical and experimental zonal drift velocities of the ionospheric plasma bubbles over the Brazilian region

    Science.gov (United States)

    Arruda, Daniela C. S.; Sobral, J. H. A.; Abdu, M. A.; Castilho, Vivian M.; Takahashi, H.; Medeiros, A. F.; Buriti, R. A.

    2006-01-01

    This work presents equatorial ionospheric plasma bubble zonal drift velocity observations and their comparison with model calculations. The bubble zonal velocities were measured using airglow OI630 nm all-sky digital images and the model calculations were performed taking into account flux-tube integrated Pedersen conductivity and conductivity weighted neutral zonal winds. The digital images were obtained from an all-sky imaging system operated over the low-latitude station Cachoeira Paulista (Geogr. 22.5S, 45W, dip angle 31.5S) during the period from October 1998 to August 2000. Out of the 138 nights of imager observation, 29 nights with the presence of plasma bubbles are used in this study. These 29 nights correspond to geomagnetically rather quiet days (∑K P hours, the calculated zonal drift velocities were found to be larger than the experimental values. The best matching between the calculated and observed zonal velocities were seen to be for a few hours around midnight. The model calculation showed two humps around 20 LT and 24 LT that were not present in the data. Average decelerations obtained from linear regression between 20 LT and 24 LT were found to be: (a) Spring 1998, -8.61 ms -1 h -1; (b) Summer 1999, -0.59 ms -1 h -1; (c) Spring 1999, -11.72 ms -1 h -1; and (d) Summer 2000, -8.59 ms -1 h -1. Notice that Summer and Winter here correspond to southern hemisphere Summer and Winter, not northern hemisphere.

  20. Intrafractional baseline drift during free breathing breast cancer radiation therapy.

    Science.gov (United States)

    Jensen, Christer Andre; Acosta Roa, Ana María; Lund, Jo-Åsmund; Frengen, Jomar

    2017-06-01

    Intrafraction motion in breast cancer radiation therapy (BCRT) has not yet been thoroughly described in the literature. It has been observed that baseline drift occurs as part of the intrafraction motion. This study aims to measure baseline drift and its incidence in free-breathing BCRT patients using an in-house developed laser system for tracking the position of the sternum. Baseline drift was monitored in 20 right-sided breast cancer patients receiving free breathing 3D-conformal RT by using an in-house developed laser system which measures one-dimensional distance in the AP direction. A total of 357 patient respiratory traces from treatment sessions were logged and analysed. Baseline drift was compared to patient positioning error measured from in-field portal imaging. The mean overall baseline drift at end of treatment sessions was -1.3 mm for the patient population. Relatively small baseline drift was observed during the first fraction; however it was clearly detected already at the second fraction. Over 90% of the baseline drift occurs during the first 3 min of each treatment session. The baseline drift rate for the population was -0.5 ± 0.2 mm/min in the posterior direction the first minute after localization. Only 4% of the treatment sessions had a 5 mm or larger baseline drift at 5 min, all towards the posterior direction. Mean baseline drift in the posterior direction in free breathing BCRT was observed in 18 of 20 patients over all treatment sessions. This study shows that there is a substantial baseline drift in free breathing BCRT patients. No clear baseline drift was observed during the first treatment session; however, baseline drift was markedly present at the rest of the sessions. Intrafraction motion due to baseline drift should be accounted for in margin calculations.

  1. Geomagnetic response to sudden expansions of the magnetosphere

    International Nuclear Information System (INIS)

    Araki, Tohru; Nagano, Hiroshi

    1988-01-01

    The geomagnetic response to five successive sudden expansions of the magnetosphere was examined by the use of magnetic data observed on the ground and by satellites. At the geosynchronous orbit between 0800 and 1100 LT the magnetic field component parallel to Earth's rotation axis decreased successively. The amplitude and the fall time of each decrease were 20-30 nT and 2.5-3.5 min, respectively. The decrease was propagated about 10 min later to the distance of about 31 R E from Earth in the antisunward direction, indicating propagation speed of about 300 km/s. The H component of ground magnetograms from low-latitude stations showed decreases with waveform similar to that at the geosynchronous orbit, but each decrease at the dayside equator was greatly enhanced and preceded by a short small positive impulse. Each of the corresponding geomagnetic variations at high latitude stations consisted of two successive sharp pulses of opposite sense with 2-3 min duration. The dominant component and the sense of these high-latitude pulses were highly dependent upon local time and latitude. The distribution of equivalent ionospheric current arrows for each high-latitude pulse showed clear twin vortices centered at 70-76 degree geomagnetic latitude in the dayside and was approximately symmetric with respect to the noon meridian. The current direction of the vortices was reversed from the first pulse to the second. it suggests successive appearance of a dawn-to-dusk and then a dusk-to-dawn electric field, both of which were transmitted from the magnetosphere to the polar ionosphere. The effect of ionospheric currents due to these polar electric fields was superposed on the simple magnetic decrease produced by an expansion of the whole magnetosphere and produced the complex waveform distribution on the ground

  2. Spectral Analysis of Geomagnetic Activity Indices and Solar Wind Parameters

    Directory of Open Access Journals (Sweden)

    Jung-Hee Kim

    2014-06-01

    Full Text Available Solar variability is widely known to affect the interplanetary space and in turn the Earth’s electromagnetical environment on the basis of common periodicities in the solar and geomagnetic activity indices. The goal of this study is twofold. Firstly, we attempt to associate modes by comparing a temporal behavior of the power of geomagnetic activity parameters since it is barely sufficient searching for common peaks with a similar periodicity in order to causally correlate geomagnetic activity parameters. As a result of the wavelet transform analysis we are able to obtain information on the temporal behavior of the power in the velocity of the solar wind, the number density of protons in the solar wind, the AE index, the Dst index, the interplanetary magnetic field, B and its three components of the GSM coordinate system, BX, BY, BZ. Secondly, we also attempt to search for any signatures of influence on the space environment near the Earth by inner planets orbiting around the Sun. Our main findings are as follows: (1 Parameters we have investigated show periodicities of ~ 27 days, ~ 13.5 days, ~ 9 days. (2 The peaks in the power spectrum of BZ appear to be split due to an unknown agent. (3 For some modes powers are not present all the time and intervals showing high powers do not always coincide. (4 Noticeable peaks do not emerge at those frequencies corresponding to the synodic and/or sidereal periods of Mercury and Venus, which leads us to conclude that the Earth’s space environment is not subject to the shadow of the inner planets as suggested earlier.

  3. K-type geomagnetic index nowcast with data quality control

    Directory of Open Access Journals (Sweden)

    René Warnant

    2011-07-01

    Full Text Available

    A nowcast system for operational estimation of a proxy K-type geomagnetic index is presented. The system is based on a fully automated computer procedure for real-time digital magnetogram data acquisition that includes screening of the dataset and removal of the outliers, estimation of the solar regular variation (SR of the geomagnetic field, calculation of the index, and issuing of an alert if storm-level activity is indicated. This is a time-controlled (rather than event-driven system that delivers the regular output of: the index value, the estimated quality flag, and eventually, an alert. The novel features provided are first, the strict control of the data input and processing, and second, the increased frequency of production of the index (every 1 h. Such quality control and increased time resolution have been found to be of crucial importance for various applications, e.g. ionospheric monitoring, that are of particular interest to us and to users of our service. The nowcast system operability, accuracy and precision have been tested with instantaneous measurements from recent years. A statistical comparison between the nowcast and the definitive index values shows that the average root-mean-square error is smaller than 1 KU. The system is now operational at the site of the Geophysical Centre of the Royal Meteorological Institute in Dourbes (50.1ºN, 4.6ºE, and it is being used for alerting users when geomagnetic storms take place.

  4. The use of various interplanetary scintillation indices within geomagnetic forecasts

    Directory of Open Access Journals (Sweden)

    E. A. Lucek

    Full Text Available Interplanetary scintillation (IPS, the twinkling of small angular diameter radio sources, is caused by the interaction of the signal with small-scale plasma irregularities in the solar wind. The technique may be used to sense remotely the near-Earth heliosphere and observations of a sufficiently large number of sources may be used to track large-scale disturbances as they propagate from close to the Sun to the Earth. Therefore, such observations have potential for use within geomagnetic forecasts. We use daily data from the Mullard Radio Astronomy Observatory, made available through the World Data Centre, to test the success of geomagnetic forecasts based on IPS observations. The approach discussed here was based on the reduction of the information in a map to a single number or series of numbers. The advantages of an index of this nature are that it may be produced routinely and that it could ideally forecast both the occurrence and intensity of geomagnetic activity. We start from an index that has already been described in the literature, INDEX35. On the basis of visual examination of the data in a full skymap format modifications were made to the way in which the index was calculated. It was hoped that these would lead to an improvement in its forecasting ability. Here we assess the forecasting potential of the index using the value of the correlation coefficient between daily Ap and the IPS index, with IPS leading by 1 day. We also compare the forecast based on the IPS index with forecasts of Ap currently released by the Space Environment Services Center (SESC. Although we find that the maximum improvement achieved is small, and does not represent a significant advance in forecasting ability, the IPS forecasts at this phase of the solar cycle are of a similar quality to those made by SESC.

  5. Relative outflow enhancements during major geomagnetic storms – Cluster observations

    Directory of Open Access Journals (Sweden)

    A. Schillings

    2017-12-01

    Full Text Available The rate of ion outflow from the polar ionosphere is known to vary by orders of magnitude, depending on the geomagnetic activity. However, the upper limit of the outflow rate during the largest geomagnetic storms is not well constrained due to poor spatial coverage during storm events. In this paper, we analyse six major geomagnetic storms between 2001 and 2004 using Cluster data. The six major storms fulfil the criteria of Dst  < −100 nT or Kp  > 7+. Since the shape of the magnetospheric regions (plasma mantle, lobe and inner magnetosphere are distorted during large magnetic storms, we use both plasma beta (β and ion characteristics to define a spatial box where the upward O+ flux scaled to an ionospheric reference altitude for the extreme event is observed. The relative enhancement of the scaled outflow in the spatial boxes as compared to the data from the full year when the storm occurred is estimated. Only O+ data were used because H+ may have a solar wind origin. The storm time data for most cases showed up as a clearly distinguishable separate peak in the distribution toward the largest fluxes observed. The relative enhancement in the outflow region during storm time is 1 to 2 orders of magnitude higher compared to less disturbed time. The largest relative scaled outflow enhancement is 83 (7 November 2004 and the highest scaled O+ outflow observed is 2  ×  1014 m−2 s−1 (29 October 2003.

  6. IAGA Geomagnetic Data Analysis format - Analysis_IAGA

    Science.gov (United States)

    -Emilian Toader, Victorin; Marmureanu, Alexandru

    2013-04-01

    Geomagnetic research involves a continuous Earth's magnetic field monitoring and software for processing large amounts of data. The Analysis_IAGA program reads and analyses files in IAGA2002 format used within the INTERMAGNET observer network. The data is made available by INTERMAGNET (http://www.intermagnet.org/Data_e.php) and NOAA - National Geophysical Data Center (ftp://ftp.ngdc.noaa.gov/wdc/geomagnetism/data/observatories/definitive) cost free for scientific use. The users of this software are those who study geomagnetism or use this data along with other atmospheric or seismic factors. Analysis_IAGA allows the visualization of files for the same station, with the feature of merging data for analyzing longer time intervals. Each file contains data collected within a 24 hour time interval with a sampling rate of 60 seconds or 1 second. Adding a large number of files may be done by dividing the sampling frequency. Also, the program has the feature of combining data files gathered from multiple stations as long as the sampling rate and time intervals are the same. Different channels may be selected, visualized and filtered individually. Channel properties can be saved and edited in a file. Data can be processed (spectral power, P / F, estimated frequency, Bz/Bx, Bz/By, convolutions and correlations on pairs of axis, discrete differentiation) and visualized along with the original signals on the same panel. With the help of cursors/magnifiers time differences can be calculated. Each channel can be analyzed separately. Signals can be filtered using bandpass, lowpass, highpass (Butterworth, Chebyshev, Inver Chebyshev, Eliptic, Bessel, Median, ZeroPath). Separate graphics visualize the spectral power, frequency spectrum histogram, the evolution of the estimated frequency, P/H, the spectral power. Adaptive JTFA spectrograms can be selected: CSD (Cone-Shaped Distribution), CWD (Choi-Williams Distribution), Gabor, STFT (short-time Fourier transform), WVD (Wigner

  7. Exploration of geomagnetic field anomaly with balloon for geophysical research

    Science.gov (United States)

    Jia, Wen-Kui

    The use of a balloon to explore the geomagnetic field anomaly in the area east of Beijing is demonstrated. The present results are compared with those of aerial surveys. Descriptions are given of the fluxgate magnetometer, the sensor's attitude control and measurement, and data transmission and processing. At an altitude of about 30 km, a positive anomaly of the vertical component of about 100 nanoteslas was measured. The results suggest that, for this particular area, the shallow layer of a small-scale geological structure differs from the deep layer of a large-scale geological structure.

  8. Ionospheric parameters as the precursors of disturbed geomagnetic conditions

    Science.gov (United States)

    Blagoveshchensky, D. V.; Sergeeva, M. A.; Kozlovsky, A.

    2017-12-01

    Geomagnetic storms and substorms are the principal elements of the disturbed Space Weather conditions. The aim of the study was to reveal the ionospheric precursors that can be used to forecast geomagnetic disturbance beginning. To study the ionospheric processes before, during and after magnetic storms and substorms data from Sodankylä Geophysical Observatory was used (geomagnetic coordinates: 64.1oN, 119.2oE). In earlier works the Main Effect (ME) was revealed for substorms. It consists of the following steps: (a) the increase of critical frequency foF2 from its quiet median before and during the substorm growth phase, four-five hours before To moment that is the moment of the expansion phase onset, (b) the foF2 decrease to the level lower than its median just after To and until Te that is the moment of the end of the expansion phase, (c) the issue ;a; repeated during the recovery phase (d) two bell-shape spikes in the cutoff frequency values foEs: first spike occurs three hours before To, second spike - during the expansion phase within the interval between To and Te. In the present work it is shown that ME manifestations can be used as precursors of magnetic substorms at high-latitudes (geomagnetic latitudes 50oN-65oN). In particular, the foF2 growth some hours before To can be used as a precursor of substorm development. The first foEs bell-shaped spike also can be used for short-term forecasting, two-three hours in advance of a substorm. Furthermore, the storms between 2008 and 2012 were studied. It was revealed that the similar ME also takes place in the case of magnetic storms but within the different time scale. More specifically, the first ME maximum in foF2 values occurs one-two days before the storm beginning and can be used as its precursor. In addition, the foEs spike takes place approximately ten hours before a storm and also can be used for the prediction of the storm beginning.

  9. Spatial power spectrum of the geomagnetic field since 1945

    International Nuclear Information System (INIS)

    Senanayake, W.E.

    1987-04-01

    The Geomagnetic field for the period 1945-1990 has been analyzed in terms of Spatial Power Spectra of the Main Field and its Secular Variation. It is observed that for the above interval, the magnetic energy density at the core-mantle boundary is almost conserved. This supports the idea that an exchange of energy between different spherical harmonic constituents could occur. The distinctive behaviour of the first two terms (Dipole and Quadrupole), as seen from the spectra of the main field and secular variation, probably indicates somewhat different feature associated with the field origin. (author). 28 refs, 3 figs, 1 tab

  10. Regional corrections and checking the reliability of geomagnetic forecasts

    International Nuclear Information System (INIS)

    Afanas'eva, V.I.; Shevnin, A.D.

    1978-01-01

    Regional corrections of the K index mark estimate with respect to the Moskva observatory are reviewed in order to improve the short-range forecast of the geomagnetic activity and to promote it within the aqua area. The forecasts of the storms of all categories and weak perturbations have been verified for the predominant days in the catalogue of the magnetic storms family. It is shown that the adopted methods of forecasts yield considerably good results for weak perturbations as well as for weak and moderate magnetic storms. Strong and very strong storms are less predictable

  11. Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

    DEFF Research Database (Denmark)

    Tomita, S; Nose´, M; Iyemori, T

    2010-01-01

    activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00-22:00MLT...

  12. Can the tardigrade Hypsibius dujardini survive in the absence of the geomagnetic field?

    Directory of Open Access Journals (Sweden)

    Weronika Erdmann

    Full Text Available Earth's geomagnetic field has undergone critical changes in the past. Studies on the influence of the magnetic field on Earth's organisms are crucial for the understanding of evolution of life on Earth and astrobiological considerations. Numerous studies conducted both on plants and animals confirmed the significant influence of the geomagnetic field on the metabolism of living organisms. Water bears (Tardigrada, which are a mong the most resistant animals due to their cryptobiotic abilities, show significant resistance to a number of environmental stressors, but the influence of the geomagnetic field on their fitness has not been addressed before. In our studies, we used eutardigrade Hypsibius dujardini to analyse whether isolation from the geomagnetic field had an effect on mortality. We found that Hypsibius dujardini specimens demonstrated relatively high mortality during anhydrobiosis, also in control groups exposed to the normal geomagnetic field. Moreover, similar mortality was observed in anhydrobiotic specimens isolated from the geomagnetic field. However, a significant difference was noted between tardigrade survival and the moment of their isolation from the geomagnetic field. In particular, tardigrade mortality substantially increased in absence of a magnetic field during the process of entering anhydrobiosis and returning to active life. Our results suggest that these processes rely on complex metabolic processes that are critically influenced by the geomagnetic field.

  13. Relation of geomagnetic pulsations to parmeters of mid-latitude lower ionosphere

    International Nuclear Information System (INIS)

    Dorokhov, V.L.; Kostrov, L.S.; Martynenko, S.I.; Piven', L.A.; Pushin, V.F.; Shemet, A.S.

    1989-01-01

    Results of experimental investigation of the effect of geomagnetic pulsations on parameters of medium-latitude lower ionosphere with the use of methods of partial reflections and Doppler probing at short waves are presented. The relation between changes in geomagnetic field and intensity of partially reflected radiosignals is detected

  14. Advancements in Chinese Geomagnetism and Aeronomy during the Last Thirty Years,

    Science.gov (United States)

    1981-02-09

    movements of charged particles in geomagnetic fields and neutral line magnetic fields and they vigorously initiated simulated tests. References (120-121... telluric prospecting and related probems; (6) Magnetic prospecting and interpretation of data; (7) Some research on geomagnetic instruments; (8

  15. The geomagnetic observatory on Tristan da Cunha: Setup, operation and experiences

    DEFF Research Database (Denmark)

    Matzka, Jürgen; Husøy, Bjørn-Ove; Berarducci, Alan

    2011-01-01

    The island Tristan da Cunha is located in the South Atlantic Anomaly, and until recently the area has been one of the largest gaps in the global geomagnetic observatory network. As part of the Danish project SAADAN we set up a geomagnetic observatory on the island. Here we report on how we establ...

  16. Climatic influence in NRM and 10 Be-derived geomagnetic paleointensity data

    NARCIS (Netherlands)

    1999-01-01

    One can determine geomagnetic paleointensities from natural remanent magnetizations (NRM) and by inverting production rates of cosmogenic isotopes such as 10 Be and 14 C. Recently, two independently derived 200-kyr stacks [Y. Guyodo, J.-P. Valet, Relative variations in geomagnetic intensity from

  17. The geomagnetic field - An explanation for the microturbulence in coaxial gun plasmas

    International Nuclear Information System (INIS)

    Mather, J.W.; Ahluwalia, H.S.

    1988-01-01

    The authors describe the complexity introduced by the geomagnetic field in several regions of a coaxial gun plasma device. It is shown that the annihilation of the swept-up geomagnetic flux, trapped within the highly compressed turbulent plasma, provides an explanation for varied performance and experimental results

  18. Effect of geomagnetic storms on VHF scintillations observed at low latitude

    Science.gov (United States)

    Singh, S. B.; Patel, Kalpana; Singh, A. K.

    2018-06-01

    A geomagnetic storm affects the dynamics and composition of the ionosphere and also offers an excellent opportunity to study the plasma dynamics. In the present study, we have used the VHF scintillations data recorded at low latitude Indian station Varanasi (Geomag. latitude = 14^{°}55^' }N, long. = 154^{°}E) which is radiated at 250 MHz from geostationary satellite UFO-02 during the period 2011-2012 to investigate the effects of geomagnetic storms on VHF scintillation. Various geomagnetic and solar indices such as Dst index, Kp index, IMF Bz and solar wind velocity (Vx) are used to describe the geomagnetic field variation observed during geomagnetic storm periods. These indices are very helpful to find out the proper investigation and possible interrelation between geomagnetic storms and observed VHF scintillation. The pre-midnight scintillation is sometimes observed when the main phase of geomagnetic storm corresponds to the pre-midnight period. It is observed that for geomagnetic storms for which the recovery phase starts post-midnight, the probability of occurrence of irregularities is enhanced during this time and extends to early morning hours.

  19. Manifestation of interplanetary medium parameters in development of a geomagnetic storm initial phase

    International Nuclear Information System (INIS)

    Chkhetiya, A.M.

    1988-01-01

    The role of solar wind plasma parameters in formation of a geomagnetic storm initial phase is refined. On the basis of statistical analysis an empirical formula relating the interplanetary medium parameters (components of interplanetary magnetic field, proton velocity and concentration) and D st -index during the geomagnetic storm initial phase is proposed

  20. The response of the 11 August 1999 total solar eclipse in the geomagnetic field

    Czech Academy of Sciences Publication Activity Database

    Střeštík, Jaroslav

    85-86, 1/3 (2001), s. 561-566 ISSN 0167-9295 R&D Projects: GA ČR GA205/99/0915 Institutional research plan: CEZ:AV0Z3012916 Keywords : geomagnetic pulsations * geomagnetic variations * total solar eclipse Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.457, year: 2001