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Sample records for geomagnetically quiet conditions

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Kalu, F. D.

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Chukwudi Okpala, Kingsley

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Zenchenko, Tatiana

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

  10. An introduction to quiet daily geomagnetic fields

    USGS Publications Warehouse

    Campbell, W.H.

    1989-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Pietrella, M.

    2013-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Pietrella, Marco

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

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

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

  18. Magnetic Signatures of Ionospheric and Magnetospheric Current Systems During Geomagnetic Quiet Conditions—An Overview

    NASA Astrophysics Data System (ADS)

    Olsen, Nils; Stolle, Claudia

    2016-09-01

    High-precision magnetic measurements taken by LEO satellites (flying at altitudes between 300 and 800 km) allow for studying the ionospheric and magnetospheric processes and electric currents that causes only weak magnetic signature of a few nanotesla during geomagnetic quiet conditions. Of particular importance for this endeavour are multipoint observations in space, such as provided by the Swarm satellite constellation mission, in order to better characterize the space-time-structure of the current systems. Focusing on geomagnetic quiet conditions, we provide an overview of ionospheric and magnetospheric sources and illustrate their magnetic signatures with Swarm satellite observations.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  20. Quiet geomagnetic field representation for all days and latitudes

    USGS Publications Warehouse

    Campbell, W.H.; Schiffmacher, E.R.; Arora, B.R.

    1992-01-01

    Describes a technique for obtaining the quiet-time geomagnetic field variation expected for all days of the year and distribution of latitudes from a limited set of selected quiet days within a year at a discrete set of locations. A data set of observatories near 75??E longitude was used as illustration. The method relies upon spatial smoothing of the decomposed spectral components. An evaluation of the fidelity of the resulting model shows correlation coefficients usually above 0.9 at the lower latitudes and near 0.7 at the higher latitudes with variations identified as dependent upon season and field element. -from Authors

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

    NASA Astrophysics Data System (ADS)

    Habyarimana, Valence

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    2016-07-01

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

  3. Achievement of a short term three dimensional electron density mapping of the ionosphere in the European sector: Comparisons with the IRI model for quiet-moderate geomagnetic-ionospheric conditions

    NASA Astrophysics Data System (ADS)

    Pietrella, M.

    2016-10-01

    In this paper will be described the procedure followed for the achievement of a short term three dimensional (3-D) electron density mapping of the ionosphere in the European area. It consists of three main steps: (1) foF2 and M(3000)F2 short-term forecasts, (foF2STF) and (M3000F2STF), are calculated at 12 ionospheric observatories scattered in the European area; (2) the values of foF2STF and M3000F2STF on a grid of equi-spaced points, (foF2STF,GP) and (M3000F2STF,GP), are calculated by means of an appropriate interpolation algorithm by using the foF2STF and M3000F2STF data; (3) foF2STF,GP and M3000F2STF,GP data ingestion into the IRI model is employed to produce a short term 3-D electron density mapping (ST-3D-M) of the ionosphere. The electron density profiles provided by the ST-3D-M and IRI models, were compared with the electron density profiles autoscaled by the Automatic Real-Time Ionogram Scaler with True-height (ARTIST) system, which are here considered as the truth profiles. The results of these comparisons, shown for a certain number of epochs during quiet-moderate geomagnetic-ionospheric conditions, in the truth-sites of Athens (38○.0‧N, 23○.5‧E), Chilton (51○.5‧N, -0○.6‧W), Dourbes (50○.1‧ N, 4○.6‧E), Pruhonice (50○.0‧N, 14○.6‧E), Rome (41○.9‧N, 12○.5‧E), and Tortosa (40○.8‧N, 0○.5‧E), indicate that the ST-3D-M as forecasting tool can be considered generally reliable.

  4. Polar convection patterns under quiet conditions

    NASA Astrophysics Data System (ADS)

    Barbosa, D. D.

    1985-10-01

    Convection electric field patterns at high latitudes appropriate to periods of low geomagnetic activity are presented. The postulate that the global Joule dissipation rate is a minimum is employed to derive characteristic field distributions for the situation when ring current ohmic losses are negligible and the auroral oval enhancement of height-integrated Hall conductivity is small. The fast Fourier transform is introduced to compute Fourier coefficients of discrete field-aligned current data, and the method is shown to be quite useful in this context as a least squares fitting routine. The model calculations demonstrate the approach of the high-latitude ionosphere toward the perfect shielding configuration predicted by the theory for quiet times.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  7. The quiet geomagnetic field at geosynchronous orbit and its dependence on solar wind dynamic pressure

    NASA Astrophysics Data System (ADS)

    Rufenach, Clifford L.; Schaper, Justin; McPherron, Robert L.

    1992-01-01

    Vector magnetic fields at geosynchronous orbit were measured during 1980-1984 using the operational GOES 2, GOES 5, and GOES 6 spacecraft magnetometers. These spacecraft measurements are corrected for offsets due to spacecraft state, and these field estimates were used to create a data base with 1-min resolution. Hourly quiet field values were calculated for these years from this data base using the ground-based geomagnetic index criteria AE less than 120 nT and absolute value of Dst less than 20 nT. These quiet field components, rotated into dipole HVD coordinates, were approximated by the first two coefficients of a two-dimensional Fourier series in time of day and season. The quiet geosynchronous field components, to first order, are given by mean values of about 90 nT, -60 nT, and 5 nT; and sinusoidal diurnal amplitudes of about 21 nT, 5 nT, and 5 nT, respectively, for H, V, and D where the spacecraft magnetometer was located near the geomagnetic meridian. The second harmonic diurnal amplitudes and the first and second harmonic seasonal amplitudes are typically of the order of a few nanoteslas or less except for the D component, which exhibits a larger seasonal variation. The H component of the quiet field increased 4.6 nT from 80.2 to 84.8 nT in its mean amplitude, and 20.8 nT from 11.9 to 32.7 nT in its first harmonic amplitude for Pd increasing from 0.71 x 10 exp -8 to 3.31 x 10 exp -8 dyn/sq cm. These quiet H measurements, including the pressure dependence, are compared with a first-order field model (Mead, 1964) superimposed with a tail current, resulting in magnetospheric currents (magnetopause and tail) in agreement with previous model values. The measured field pressure dependence and the Mead model suggest a tail current dependence on pressure.

  8. Some effects of quiet geomagnetic field changes upon values used for main field modeling

    USGS Publications Warehouse

    Campbell, W.H.

    1987-01-01

    The effects of three methods of data selection upon the assumed main field levels for geomagnetic observatory records used in main field modeling were investigated for a year of very low solar-terrestrial activity. The first method concerned the differences between the year's average of quiet day field values and the average of all values during the year. For H these differences were 2-3 gammas, for D they were -0.04 to -0.12???, for Z the differences were negligible. The second method of selection concerned the effects of the daytime internal Sq variations upon the daily mean values of field. The midnight field levels when the Sq currents were a minimum deviated from the daily mean levels by as much as 4-7 gammas in H and Z but were negligible for D. The third method of selection was designed to avoid the annual and semi-annual quiet level changes of field caused by the seasonal changes in the magnetosphere. Contributions from these changes were found to be as much as 4-7 gammas in quiet years and expected to be greater than 10 gammas in active years. Suggestions for improved methods of improved data selection in main field modeling are given. ?? 1987.

  9. Characteristics of the large-scale traveling atmospheric disturbances during geomagnetically quiet and disturbed periods simulated by a whole atmosphere general circulation model

    NASA Astrophysics Data System (ADS)

    Fujiwara, Hitoshi; Miyoshi, Yasunobu

    2006-10-01

    We have investigated characteristics of the large-scale traveling atmospheric disturbances (LS-TADs) generated during geomagnetically quiet and disturbed periods using a whole atmosphere general circulation model (GCM). The GCM simulations show that various TADs appear in association with passages of regions with large temperature gradients near the solar terminator, midnight temperature anomaly, and auroral oval which move with the Earth's rotation. These TADs, which are superimposed on each other, appear even when a geomagnetically quiet period. The TADs generated during a geomagnetically quiet period show structures extending in the longitudinal direction at high-latitude and in the latitudinal direction at mid- and low-latitude. These structures disappear after their short-range propagations. The TADs generated during a geomagnetically disturbed period show structures extending widely in the longitudinal direction and propagate from high- to low-latitude. These simulation results suggest the different generation mechanisms and features between the TADs generated during geomagnetically quiet and disturbed periods.

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

    SciTech Connect

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

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. Observations of magnetospheric high-m poloidal waves by ST-5 satellites in low Earth orbit during geomagnetically quiet times

    NASA Astrophysics Data System (ADS)

    Chi, P. J.; Le, G.

    2015-06-01

    The poloidal waves with large azimuthal wave numbers (m) in the magnetosphere are known to be generated by drift or drift-bounce resonance with energetic ring current particles, and these waves may play a role in modulating the energetic particles in the inner magnetosphere. When examining the magnetic field data collected by the NASA Space Technology 5 (ST-5) satellites in the low Earth orbit, Le et al. (2011) discovered many wave events with frequencies of 30-200 mHz (in the Pc2 and Pc3 bands), and they proposed that these waves should, in fact, be Doppler-shifted high-m poloidal waves in the magnetosphere with frequencies at only a few millihertz (in the Pc5 band). Using a new method that examines the differences in wave phase detected by the three ST-5 satellites, we confirm that the frequencies in the Earth frame for the poloidal waves observed are mainly between 3 and 5 mHz. Not only were poloidal waves observed frequently by ST-5 in the dayside magnetosphere but they were also occasionally seen in the nightside when the satellites passed through the same L shells. In each wave event, the azimuthal wave number may change with L, but the wave frequency in the Earth frame remains the same. We also find that poloidal waves can last more than 9 h during geomagnetically quiet conditions, suggesting that even a very weak ring current can supply enough energetic particles to excite poloidal waves.

  13. Mapping Geomagnetic Field Variations in the Cretaceous Quiet Zone with Unmanned Airborne Vehicles

    NASA Astrophysics Data System (ADS)

    Gee, J. S.; Cande, S. C.; Kent, D. V.

    2007-12-01

    About one quarter of the present seafloor was generated during the constant normal polarity interval from 121 to 83 Ma (Cretaceous Quiet Zone or KQZ), and the lack of temporal markers limits tectonic reconstructions in these areas. Although magnetostratigraphic studies provide strong evidence that the KQZ formed during predominantly normal polarity, there are nonetheless relatively large amplitude variations in many sea surface magnetic anomaly profiles crossing KQZ crust. To evaluate the relative importance of geomagnetic and crustal variables (thickness, geochemistry) in generating these anomalies, we collected multibeam bathymetry and magnetic data on 19 profiles crossing anomaly 34 and extending 500 km into the KQZ in the southwest Pacific. The relatively fast spreading (60 km/m.y. half rate), minimal sediment cover and high paleolatitude of formation make this area ideal for evaluating the magnetic anomaly pattern. An additional 10,000 km of magnetic anomaly data were acquired using an autonomous unmanned airborne vehicle (UAV). Although land-launched UAVs have been used in a variety of research applications, the nine successful flights during our cruise represent the first deployment from a UNOLS research vessel. The UAV (operated by Fugro Airborne) was launched from a pneumatic catapult and captured by a wingtip clip that attaches to a rope suspended from a retractable boom on the fantail. The Cs-vapor magnetometer data from the UAV compare favorably with results from the surface-towed magnetometer, with minor differences related primarily to the higher elevation (120m above sea level) of the UAV. The resulting magnetic coverage indicates that, as with younger seafloor, quasi-linear short wavelength anomalies are present within the KQZ. These anomalies can vary on spatial scales smaller than the multibeam swath width, highlighting the utility of obtaining additional coverage with the UAVs.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  17. Thermospheric/ionospheric disturbances under quiet and magneto-perturbed conditions

    NASA Astrophysics Data System (ADS)

    Zakharov, Ivan G.; Mozgovaya, O. L.

    2003-04-01

    The basic mechanisms of ionospheric storms (IS) are investigated sufficiently full. Despite of it a quantitative forecast of ionospheric disturbance is not always satisfactory. One of the possible causes can be related to the insufficient account of a background ionospheric. In particualr using electron concentration Ne in the peak of F2-region and total electron content are shown, that the amplitude of a IS positive phase for similar magnetic storms can differ by ~1,5 times. Hence a cause of distinction can be variations in the thermosphere conditions, not reflected by known activity indices. For further research we used the incoherent scatter radar data of the Institute of ionosphere in height range 200-1000 km in the very quiet periods coming to the geomagnetic disturbance. A steady periodic disturbance in Ne during quiet conditions in all heights is established, which can be identified as tidal moda m=6. The amplitude of wave is ~15%, the phase changes with a height. The storm onset leads to an increase of the amplitudes approximately twice without a change in the phase. An ionospheric disturbance in very quiet conditions can lead to additional complicating an ionosphere reaction to magnetic storm.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  19. Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times.

    PubMed

    Shi, Q Q; Zong, Q-G; Fu, S Y; Dunlop, M W; Pu, Z Y; Parks, G K; Wei, Y; Li, W H; Zhang, H; Nowada, M; Wang, Y B; Sun, W J; Xiao, T; Reme, H; Carr, C; Fazakerley, A N; Lucek, E

    2013-01-01

    An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times. PMID:23403567

  20. Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times.

    PubMed

    Shi, Q Q; Zong, Q-G; Fu, S Y; Dunlop, M W; Pu, Z Y; Parks, G K; Wei, Y; Li, W H; Zhang, H; Nowada, M; Wang, Y B; Sun, W J; Xiao, T; Reme, H; Carr, C; Fazakerley, A N; Lucek, E

    2013-01-01

    An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times.

  1. Forecasting Geomagnetic Conditions in near-Earth space

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Xu, Zhonghua

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Pietrella, M.

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Chu, W.; Qin, G.

    2016-01-01

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

  6. Distant (200-238 earth radii) magnetotail lobe characteristics during quiet solar wind conditions

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Burton, Marcia E.; Smith, Edward J.; Jones, Douglas E.; Lepping, Ronald P.

    1987-01-01

    Simultaneous ISEE-3 magnetic field and IMP-8 magnetic field and plasma data have been used to investigate the distant tail lobe average properties under quiet solar wind conditions. Under solar wind pressures of not greater than 5 x 10 to the -10th dynes/sq cm, an average tail lobe strength of 7.1 + or - 1.2 nT, and an average plasma beta of 0.3, are found. Results suggest that under quiet solar wind conditions the distant tail lobes are relatively free from plasma and are usually dominated by the magnetic field pressure.

  7. Mapping the earth conductivity-depth structure of African geomagnetic equatorial anomaly regions using solar quiet current variations

    NASA Astrophysics Data System (ADS)

    Ugbor, D. O.; Okeke, F. N.; Yumoto, K.

    2016-04-01

    The solar quiet day ionospheric (Sq) current variations observed in Abuja, Bangui and Addis Ababa were used to delineate the mantle conductivity-depth structure along the equatorial African regions. Spherical harmonic analysis (SHA) was employed in separating the internal and external field contributions to the Sq variations. For each of the paired external and internal coefficients of the SHA, we used transfer function to compute the conductivity-depth profile for the region. Strikingly, we observed increased electrical conductivity values in the Earth layers and deep depth penetration. The calculated average electrical conductivity values in Addis Ababa and Abuja are 0.087 Sm-1 and 0.104 Sm-1 at depths of 93 km and 121 km respectively. These values suddenly rose to 0.235 Sm-1 and 0.222 Sm-1 at depths of 440 km and 427 km respectively. In Bangui, the calculated average values are 0.092 Sm-1, 0.144 Sm-1, 0.312 Sm-1 and 0.466 Sm-1 at 96 km, 300 km, 834 km and 1228 km depths respectively. At the greatest depths of penetration of 1412 km, 1385 km and 1278 km in Addis Ababa, Abuja and Bangui, the electrical conductivity attained the highest values of 0.415 Sm-1, 0.467 Sm-1 and 0.515 Sm-1 respectively. Two most Earth conductive layers were discovered in the magnetic equatorial zone. These layers lie between the depth of about 100 and 400 km within the upper mantle and beyond 1200 km in the lower mantle. It can be inferred that the closer one goes towards the Earth magnetic equator; the deeper the Sq current can penetrate the Earth's interior.

  8. Thermosphere Response to Geomagnetic Variability during Solar Minimum Conditions

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  9. Characteristics of long-term variation in the amlitude of the geomagnetic solar quiet (Sq) daily variation using the Inter-university Upper atmosphere Gobal Observation NETwork (IUGONET) data analysis system

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Characteristics of long-term variation in the amplitude of solar quiet geomagnetic field daily variation (Sq) have been investigated using 1-hour geomagnetic field data obtained from 69 geomagnetic stations in a period of 1947-2013. In the present data analysis, we took advantage of the IUGONET data analysis system. The Sq amplitude clearly showed a 10-12 year solar activity dependence and it tended to enhance during each solar maximum. During the minimum of solar cycle 23/24 in 2008-2009, the Sq amplitude became the smallest in the investigated period. The relationship between the solar F10.7 index and Sq amplitude is approximately linear but 64 percent of geomagnetic stations show a weak nonlinear dependence on the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second order fitting curve between the solar F10.7 index and Sq amplitude during 1947-2013, and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, a majority of the trends in the residual Sq amplitude that passed through a trend test showed a negative value in a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity and residual Sq amplitude showed an anti-correlation for about 71 percent of geomagnetic stations. On the other hand, the residual Sq amplitude in the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies the movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

  10. Vertical variations of charged-particle temperature and density in quiet conditions

    NASA Astrophysics Data System (ADS)

    Apati, I.; Semerei, T.; Afonin, V.; Bezrukikh, V.; Shiutte, N.; Bentse, P.

    1983-09-01

    Electrostatic analyzers aboard the Vertical-6 rocket were used to study vertical variations of charged-particle temperature and density at heights of 200-1200 km during quiet-solar conditions on October 25, 1977. The heating of the electron-ion gas was found to have an essentially nonmonotonic character. Above the F-region maximum, significant fluctuations of ion-gas temperature were observed, apparently associated with vertical variations of cooling and heating due to the excitation of the fine structure of atomic-oxygen levels as well as due to the effect of ion-exchange reactions. The maximum heating of ion gas occurs at heights where hydrogen ions begin to predominate. It is noted that the results obtained can be used to improve existing ionospheric models relating to periods of low solar activity.

  11. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing...

  12. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing...

  13. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing...

  14. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing...

  15. 49 CFR 222.51 - Under what conditions will quiet zone status be terminated?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... under 49 U.S.C. 20104 and 49 CFR part 211. (d) Termination by the public authority. (1) Any public...-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings... SSM at every public crossing within the quiet zone or for quiet zones established by reducing...

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Su, F.

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Kaushik, Subhash Chandra

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

  20. Ionospheric manifestations of acoustic-gravity waves under quiet and disturbed conditions

    NASA Astrophysics Data System (ADS)

    Barabash, Vladimir; Chernogor, Leonid; Panasenko, Sergii; Domnin, Igor

    2014-05-01

    We present the observation results of wave disturbances in the ionosphere, which are known to be manifestations of atmospheric acoustic-gravity waves (AGWs). The observations have been conducted under quiet and naturally or artificially disturbed conditions by ionosonde and incoherent scatter radar located near Kharkiv, Ukraine. Wave disturbance parameters under quiet conditions were obtained and analysed during geophysical periods including vernal and autumn equinoxes as well as summer and winter solstices. The prevailing oscillation in ionospheric F2- layer had the period of 140 - 200 min and relative amplitude of 0.1 - 0.2. The duration of this oscillation changed from 5 - 7 to 24 hours, depending on a season. The amplitude of fluctuations with other periods was noticeably smaller. The time intervals at which the intensity of incoherent scatter signals varied quasi-periodically in the altitude range from 150 to 300 km were detected. The parameters of these variations were estimated using statistical analysis and bandpass filtering. The periods of wave processes were shown to be of 30 - 120 min, there durations did not exceed of 2 - 6 periods and relative amplitudes usually ranged from 0.03 to 0.15. The phase of oscillations was detected to propagate downwards. The vertical phase velocity of travelling ionospheric disturbances (TIDs) was estimated to be in the range from 50 to 200 m/s and increased with altitude. The observations of the partial solar eclipse on January, 4, 2011 near Kharkiv were used to study the ionospheric parameters in naturally disturbed conditions. The F2-layer critical frequency dropped by a factor of 2.1. The time delay of these variations with respect to the main magnitude of the solar disk obscuration was equal to about 16 minutes. The virtual height of signal reflection near the maximum of the F2-layer ionization increased by 70 km, and the height of the model parabolic layer increased by 10 km. Some decrease in electron density and

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Uwamahoro, Jean Claude; Habarulema, John Bosco

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Biktash, Lilia

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  12. Introduction to Geomagnetic Fields: Second Edition

    NASA Astrophysics Data System (ADS)

    Campbell, Wallace H.

    2003-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. The role of high-resolution geomagnetic field models for investigating ionospheric currents at low Earth orbit satellites

    NASA Astrophysics Data System (ADS)

    Stolle, Claudia; Michaelis, Ingo; Rauberg, Jan

    2016-07-01

    Low Earth orbiting geomagnetic satellite missions, such as the Swarm satellite mission, are the only means to monitor and investigate ionospheric currents on a global scale and to make in situ measurements of F region currents. High-precision geomagnetic satellite missions are also able to detect ionospheric currents during quiet-time geomagnetic conditions that only have few nanotesla amplitudes in the magnetic field. An efficient method to isolate the ionospheric signals from satellite magnetic field measurements has been the use of residuals between the observations and predictions from empirical geomagnetic models for other geomagnetic sources, such as the core and lithospheric field or signals from the quiet-time magnetospheric currents. This study aims at highlighting the importance of high-resolution magnetic field models that are able to predict the lithospheric field and that consider the quiet-time magnetosphere for reliably isolating signatures from ionospheric currents during geomagnetically quiet times. The effects on the detection of ionospheric currents arising from neglecting the lithospheric and magnetospheric sources are discussed on the example of four Swarm orbits during very quiet times. The respective orbits show a broad range of typical scenarios, such as strong and weak ionospheric signal (during day- and nighttime, respectively) superimposed over strong and weak lithospheric signals. If predictions from the lithosphere or magnetosphere are not properly considered, the amplitude of the ionospheric currents, such as the midlatitude Sq currents or the equatorial electrojet (EEJ), is modulated by 10-15 % in the examples shown. An analysis from several orbits above the African sector, where the lithospheric field is significant, showed that the peak value of the signatures of the EEJ is in error by 5 % in average when lithospheric contributions are not considered, which is in the range of uncertainties of present empirical models of the EEJ.

  16. Long-period irregular pulsations under the conditions of a quiet magnetosphere

    NASA Astrophysics Data System (ADS)

    Kurazhkovskaya, N. A.; Klain, B. I.; Lavrov, I. P.

    2016-05-01

    Simultaneous observations of high-latitude long-period irregular pulsations at frequencies of 2.0-6.0 mHz ( ipcl) and magnetic field disturbances in the solar wind plasma at low geomagnetic activity ( Kp ~ 0) have been studied. The 1-s data on the magnetic field registration at Godhavn (GDH) high-latitude observatory and the 1-min data on the solar wind plasma and IMF parameters for 2011-2013 were used in an analysis. Ipcl (irregular pulsations continuous, long), which were observed against a background of the IMF Bz reorientation from northward to southward, have been analyzed. In this case other solar wind plasma and IMF parameters, such as velocity V, density n, solar wind dynamic pressure P = ρ V 2 (ρ is plasma density), and strength magnitude B, were relatively stable. The effect of the IMF Bz variation rate on the ipcl spectral composition and intensity has been studied. It was established that the ipcl spectral density reaches its maximum (~10-20 min) after IMF Bz sign reversal in a predominant number of cases. It was detected that the ipcl average frequency ( f) is linearly related to the IMF Bz variation rate (Δ Bz/Δ t). It was shown that the dependence of f on Δ Bz/Δ t is controlled by the α = arctan( By/ Bx) angle value responsible for the MHD discontinuity type at the front boundary of magnetosphere. The results made it possible to assume that the formation of the observed ipcl spectrum, which is related to the IMF Bz reorientation, is caused by solar wind plasma turbulence, which promotes the development of current sheet instability and surface wave amplification at the magnetopause.

  17. Quiet Ride

    ERIC Educational Resources Information Center

    Rathey, Allen

    2006-01-01

    Several companies are marketing maintenance equipment to education institutions on a "quiet platform," citing benefits such as a safer, more pleasant indoor environment and unobtrusive operations during day cleaning or operating hours. This is basically "sound advice" (no one likes noisy equipment), but some of the messages can be confusing and…

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  19. Unusual noon-time bite-outs in the ionospheric electron density around the anomaly crest locations over the Indian and Brazilian sectors during quiet conditions - A case study

    NASA Astrophysics Data System (ADS)

    Venkatesh, K.; Fagundes, P. R.; de Abreu, A. J.; Pillat, V. G.

    2016-09-01

    The present case study reports the unusual noon-time electron density bite-out events during 12th-18th April 2004 around the anomaly crest locations which are not observed over the geomagnetic equator. These bite-out events at the crest locations occurred on three consecutive days under solar and geomagnetically quiet conditions over the Indian and Brazilian sectors. The bite-out events are observed with a delay of two days over the Brazilian sector when compared with those in the Indian sector. The duration of these TEC bite-outs is found to vary around 5 h in the Indian sector while it is around 3 h in the Brazilian sector. Over Raipur in the Indian sector, the bite-out is found to be very strong (~30 TECU) on 13th April 2004, where the TEC drops to nearly 50% of the corresponding day maximum TEC. The diurnal variations of dTEC have also shown significant differences during the occurrence of noon-time TEC bite-outs. Simultaneous Equatorial Electrojet (EEJ) variations over the Indian and Brazilian sectors have also been studied. The ionosonde data over the equatorial and anomaly crest locations has been analyzed to understand the F-layer behavior during the occurrence of TEC bite-outs. Significant drop in the F-layer peak density and heights are observed during the TEC bite-outs while the minimum height of the bottom side F-layer do not show considerable differences. Further, the variations of vertical electron density profiles are studied to explain the F-layer characteristics that resulted in the noon-time bite-outs over the anomaly crest locations.

  20. Modeling the Quiet Time Outflow Solution in the Polar Cap

    NASA Technical Reports Server (NTRS)

    Glocer, Alex

    2011-01-01

    We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum, The PWOM solves the gyrotropic transport equations for O(+), H(+), and He(+) along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. [2011] of electron density, which is based on 63 months of Akebono satellite observations. The modeled ion and electron temperatures are also compared with a statistical compilation of quiet time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites (Kitamura et al. [2011]). The data and model agree reasonably well. This study shows that photoelectrons play an important role in explaining the differences between sunlit and dark results, ion composition, as well as ion and electron temperatures of the quiet time polar wind solution. Moreover, these results provide validation of the PWOM's ability to model the quiet time ((background" solution.

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

    NASA Astrophysics Data System (ADS)

    Nagatsuma, T.

    2009-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  3. Achieving a quiet rooftop installation

    SciTech Connect

    Harold, R.G.

    1993-12-01

    This article examines the design considerations for quiet roof top installations of air conditioning systems. The topics of the article include the elements of a quiet installation, acoustic design requirements for minimizing noise problems, incorporating system requirements into the overall design of the building, and survival of the system design through bid review and installation.

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Singh, Vir; Dharwan, Maneesha

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Driscoll, Peter E.

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

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

    NASA Astrophysics Data System (ADS)

    Ulukavak, Mustafa; Yalcinkaya, Mualla

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  11. Indian Institute of Geomagnetism: Progress in research

    NASA Astrophysics Data System (ADS)

    Progress and aspects is the study of the geomagnetic variations in the Indian region on quiet and disturbed days, equatorial electrojet field, electromagnetic induction in the earth, magnetic pulsations, aeronomy, radio scintillations, magnetosphere and solar wind, and solar-terrestrial relationships were reported.

  12. Geomagnetism applications

    USGS Publications Warehouse

    Campbell, Wallace H.

    1995-01-01

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

  13. Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles

    NASA Astrophysics Data System (ADS)

    Balachandra Swamy, A. C.

    EXTENDED ABSTRACT Pulsed HF radiowave absorption measurements at 2.1 MHZ. over Delhi under quiet and solar flare conditions and related electron density height profiles A.C.Balachandra swmay & Late C.S.G.K. Setty Absorption of radio waves in the ionosphere is of great practical importance for radio communication and navigation systems. The first attempt to measure the absolute magnitude of the radiowave absorption were made by appletion and Ratcliffe (1930) using the frequency change method for medium frequency waves reflected from the E-region. They concluded from their experiment that the main part of the attenuation occurred below the reflection level and named the absorption region, D-region of the ionosphere. One of the basic properties of the ionosphere is the absorption of high Frequency Radiowaves. HF radiowave absorption results mainly from collisions between electrons (which are set into forced oscillations by the electric field of the wave) and neutral air particles, the RF energy abstracted from the wave being converted into thermal energy. The radiowave absorption in the ionosphere depends on electron density and collision frequency. The most important absorbing regions are the D-region and the lower E-region (50-100 Km.) The regular diurnal variation of the electron density in this height range is caused mainly by the changes in the depth of penetration of solar XUV radiations with solar zenith angle under quiet solar conditions. In 1937 Dellinger J.H.identified fade outs in high frequency radio circuits as due to abnormal ionospheric absorption associated with solar flares. The onset of the fade out was usually rapid and the duration was typically tens of minutes like that of the visible flare, because of the sudden onset, the immediate effects of solar flares are known collectively as sudden Ionospheric Disturbances (STD). The phenomenon discovered by Dellinger is usually called a short Wave Fadeout(SWF). Since the SWF is due to abnormal absorption

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

    NASA Astrophysics Data System (ADS)

    Huang, Sheng; Du, Aimin; Cao, Xin

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  16. F2 region response to geomagnetic disturbances across Indian latitudes: O(1S) dayglow emission

    NASA Astrophysics Data System (ADS)

    Upadhayaya, A. K.; Gupta, Sumedha; Brahmanandam, P. S.

    2016-03-01

    The morphology of ionospheric storms has been investigated across equatorial and low latitudes of Indian region. The deviation in F2 region characteristic parameters (foF2 and h'F) along with modeled green line dayglow emission intensities is examined at equatorial station Thiruvananthapuram (8.5°N, 76.8°E, 0.63°S geomagnetic latitude) and low-latitude station Delhi (28.6°N, 77.2°E,19.2°N geomagnetic latitude) during five geomagnetic storm events. Both positive and negative phases have been noticed in this study. The positive storm phase over equatorial station is found to be more frequent, while the drop in ionization in most of the cases was observed at low-latitude station. It is concluded that the reaction as seen at different ionospheric stations may be quite different during the same storm depending on both the geographic and geomagnetic coordinates of the station, storm intensity, and the storm onset time. Modulation in the F2 layer critical frequency at low and equatorial stations during geomagnetic disturbance of 20-23 November 2003 was caused by the storm-induced changes in O/N2. It is also found that International Reference Ionosphere 2012 model predicts the F2 layer characteristic (foF2 and h'F) parameters at both the low and equatorial stations during disturbed days quite reasonably. A simulative approach in GLOW model developed by Solomon is further used to estimate the changes in the volume emission rate of green line dayglow emission under quiet and strong geomagnetic conditions. It is found that the O(1S) dayglow thermospheric emission peak responds to varying geomagnetic conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  18. Inter-hourly variability of Total Electron Content during the quiet condition over Nigeria, within the Equatorial Ionization Anomaly region

    NASA Astrophysics Data System (ADS)

    Ayorinde, T. T.; Rabiu, A. B.; Amory-Mazaudier, C.

    2016-07-01

    The inter-hourly variability (IHV) of the Total Electron Content (TEC) over Nigeria during the quiet days (Ap<4) of the year 2013 was examined using ground-based GPS receivers installed at seven (7) different locations across Nigeria by the Nigerian Global Navigation Satellite Systems (GNSS) Reference Network (NIGNET) operated by the office of the surveyor general of Nigeria. Nigeria is a country that lies within Equatorial Ionospheric Anomaly (EIA) region. The IHV was calculated by converting the observed hourly slant TEC (STEC) value into the hourly vertical TEC (VTEC) and the differencing (∆TEC) with its corresponding hourly value from the previous day. There is a clear variation which depicts the expected temporal variability. The IHV in TEC in all the stations ranges between 0 and 20 TECU (TEC Units). The seasonal variation of the IHV of TEC over Nigeria maximizes (5-20 TECU) during Equinoctial months and minimizes (1-10 TECU) during the Solstice months. The IHV of TEC in September equinox period is higher than that of March equinox. Minimum value of IHV (~7 TECU at equinoxes and ~5 TECU at Solstice) was recorded at the Office of Surveyor General of the Federation (OSGF) station and the maximum value (~12 TECU at equinoxes and ~16 TECU at Solstice) was recorded at the Birni Kebbi Federal Polytechnic (BKFP) station which may be due to the fact that BKFP at 0.72° dip latitude is closer to the dip equator.

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

    SciTech Connect

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

    1989-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  2. Great Lakes Region Morphology and Impacts of March 17, 2015 SED Geomagnetic Storm

    NASA Astrophysics Data System (ADS)

    Heine, T.; Moldwin, M.; Zou, S.

    2015-12-01

    Under quiet geomagnetic conditions, the mid-latitude ionosphere is relatively uniform with little spatial variation in electron density. However, during intense geomagnetic storms, density gradients associated with Storm Enhanced Density (SED) plumes and Sub-auroral Polarization Streams (SAPS) can move across the dayside mid-latitude ionosphere producing small spatial scale density structure that may be connected to ionospheric scintillation. The evolution of the SED plume during the March 17, 2015 "St. Patrick's Day Storm" is investigated using aggregated data from high resolution GPS receivers at the University of Michigan and throughout the Great Lakes region. Structural density features in the SED gradient can be observed and compared to GPS scintillation measurements—providing insight into the physical mechanisms behind ionospheric scintillation.

  3. Geomagnetic transmission of solar energetic protons during the geomagnetic disturbances of October 1989

    NASA Technical Reports Server (NTRS)

    Boberg, P. R.; Tylka, A. J.; Adams J. H., JR.; Flueckiger, E. O.; Kobel, E.

    1995-01-01

    Orbit-averaged geomagnetic transmission measurements during the large solar energetic particle events of October 1989 are presented using proton data from the NOAA-10 and GOES-7 satellies. The measurements are compared to geomagnetic transmission calculations determined by tracing particle trajectories through the combination of the International Geomagnetic Reference Field (IGRF) model and the 1989 Tsyganenko magnetospheric magnetic field model. The effective 'ring current' parameter in the 1989 Tsyganenko model based on the Dst data. Results are compared to calculations employing only the IGRF and to a parameterization of geomagnetically quiet-time cutoff rigidities derived from Cosmos/intercosmos observations. The 3-hour orbit-averaged results have approximately 15% accuracy during the October 1989 events.

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

    NASA Astrophysics Data System (ADS)

    Fang, Hanxian; Weng, Libin; Sheng, Zheng

    2012-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  8. Dynamic Geomagnetic Hazard Maps in Space Weather Operations

    NASA Astrophysics Data System (ADS)

    Rigler, E. J.; Pulkkinen, A. A.; Balch, C. C.; Wiltberger, M. J.

    2014-12-01

    Traditionally, the use of geomagnetic data in space weather operations has been limited to specific geographic coordinates (i.e., magnetic observatories), or to global indices that average magnetic measurements into latitudinal bands of relatively general space weather interest (e.g., Dst, Kp, AE). However, modern technological systems (e.g., power grids, directional drilling platforms) are beginning to require and request information about ground magnetic variations that is more tailored to a specific locale. One solution is to simply install magnetic observatories near every newly built technological system, but this is both economically and operationally impractical. We have chosen instead to adopt an optimal interpolation scheme that inverts for spherical elementary current systems (SECS, Amm-1997), which in turn are used to fill gaps between magnetic observatories. The SECS technique has undergone extensive scientific vetting over the last decade-and-a-half, and will soon be implemented operationally over the continental U.S. as a joint NASA-NOAA-USGS space weather data product, disseminated by the Space Weather Prediction Center (SWPC). Because it will employ a relatively sparse array of high-quality geomagnetic observatories as input, it is important to characterize its ability to reproduce spatial variations in geomagnetic field at sub-continental scales, so the Lyon-Fedder-Mobarry (LFM) global geospace model is used to generate realistic synthetic observations. These include virtual magnetic observatories as input, and a regular geographic grid to serve as a proxy for "ground truth". We look specifically at LFM output for the Whole Heliosphere Interval (WHI) in order to obtain statistically valid performance measures for a variety of quiet-to-moderate space weather conditions.

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

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

    SciTech Connect

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

    1997-07-01

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

  11. Rapid and Quiet Drill

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Chang, Zensheu; Bao, Xiaoqi

    2007-01-01

    This describes aspects of the rapid and quiet drill (RAQD), which is a prototype apparatus for drilling concrete or bricks. The design and basic principle of operation of the RAQD overlap, in several respects, with those of ultrasonic/ sonic drilling and coring apparatuses described in a number of previous NASA Tech Briefs articles. The main difference is that whereas the actuation scheme of the prior apparatuses is partly ultrasonic and partly sonic, the actuation scheme of the RAQD is purely ultrasonic. Hence, even though the RAQD generates considerable sound, it is characterized as quiet because most or all of the sound is above the frequency range of human hearing.

  12. Microbial proteomics: the quiet revolution

    SciTech Connect

    Seraphin, Bertrand; Hettich, Robert {Bob} L

    2012-01-01

    Technological developments in DNA sequencing and their application to study thousands of microbial genomes or even microbial ecosystems still today often make the headlines of general newspapers and scientific journals. These revolutionary changes are hiding another revolution that is unfolding more quietly in the background: the development of microbial proteomics to study genome expression products. It is important to recognize that while DNA sequencing reveals extensive details about the genomic potential of an organism or community, proteomic measurements reveal the functional gene products that are present and operational under specific environmental conditions, and thus perhaps better characterize the critical biomolecules that execute the life processes (enzymes, signaling, structural factors, etc.).

  13. The Quiet Skies Project

    ERIC Educational Resources Information Center

    Rapp, Steve

    2008-01-01

    To help promote student awareness of the connection between radio astronomy and radio frequency interference (RFI), an inquiry-based science curriculum was developed to allow high school students to determine RFI levels in their communities. The Quiet Skies Project--the result of a collaboration between the National Aeronautics and Space…

  14. Solar activity dependence of nightside aurora in winter conditions

    NASA Astrophysics Data System (ADS)

    Zhou, Su; Luan, Xiaoli; Dou, Xiankang

    2016-02-01

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

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

    NASA Technical Reports Server (NTRS)

    Halenka, J.

    1979-01-01

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

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

    PubMed

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

    2012-10-01

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

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

    PubMed

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

    2008-10-01

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

  18. Simulation of Theoretical Most-Extreme Geomagnetic Sudden Commencements

    NASA Astrophysics Data System (ADS)

    Welling, Daniel; Love, Jeffrey; Wiltberger, Michael; Rigler, Erin; Gombosi, Tamas

    2016-04-01

    We report results from a numerical simulation of geomagnetic sudden commencements driven by solar wind conditions given by theoretical-limit extreme coronal-mass ejections (CMEs) estimated by Tsurutani and Lakhina [2014]. The CME characteristics at Earth are a step function that jumps from typical quiet values to 2700 km/s flow speed and a magnetic field magnitude of 127 nT. These values are used to drive three coupled models: a global magnetohydrodynamic (MHD) magnetospheric model (BATS-R-US), a ring current model (the Rice Convection Model, RCM), and a height-integrated ionospheric electrodynamics model (the Ridley Ionosphere Model, RIM), all coupled together using the Space Weather Modeling Framework (SWMF). Additionally, simulations from the Lyon-Fedder-Mobarry MHD model are performed for comparison. The commencement is simulated with both purely northward and southward IMF orientations. Low-latitude ground-level geomagnetic variations, both B and dB/dt, are estimated in response to the storm sudden commencement. For a northward interplanetary magnetic field (IMF) storm, the combined models predict a maximum sudden commencement response, Dst-equivalent of +200 nT and a maximum local dB/dt of ~200nT/s. While this positive Dst response is driven mainly by magnetopause currents, complicated and dynamic Birkeland current patterns also develop, which drive the strong dB/dt responses at high latitude. For southward IMF conditions, erosion of dayside magnetic flux allows magnetopause currents to approach much closer to the Earth, leading to a stronger terrestrial response (Dst-equivalent of +250 nT). Further, high latitude signals from Region 1 Birkeland currents move to lower latitudes during the southward IMF case, increasing the risk to populated areas around the globe. Results inform fundamental understanding of solar-terrestrial interaction and benchmark estimates for induction hazards of interest to the electric-power grid industry.

  19. The QUIET Instrument

    NASA Technical Reports Server (NTRS)

    Gaier, T.; Kangaslahti, P.; Lawrence, C. R.; Leitch, E. M.; Wollack, E. J.

    2012-01-01

    The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ( approx 1 deg.) . Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 micro Ks(exp 1/2)) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 micro Ks(exp 1/2) at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01 (QUIET Collaboration 2012) The two arrays together cover multipoles in the range l approximately equals 25-975 . These are the largest HEMT-ba.sed arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument,

  20. Range indices of geomagnetic activity

    USGS Publications Warehouse

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

    1988-01-01

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

  1. A description of the external and internal quiet daily variation currents at North American locations for a quiet-Sun year.

    USGS Publications Warehouse

    Campbell, W.H.

    1983-01-01

    An order 4, degree 12 spherical harmonic analysis of the smoothed quiet geomagnetic daily variations was used to separate the external and internal geomagnetic Sq field at North American locations for the quiet-Sun year, 1965. These fields were represented by a month-by-month display of equivalent current vortex systems with dominant, pre-noon foci. The focus reached 40o latitude near the June solstice and about 30o latitude near the December solstice. The daily range of Sq current amplitudes was largest in late July to early August and smallest in mid-December. Semi-annual variations of Sq currents dominated only the equatorial region. Daily maxima in mid-latitudes, occurred mostly near local noon in December to February and about 1 hr before noon in June to mid-October. -Author

  2. Microwave Properties of Quiet Seas

    NASA Technical Reports Server (NTRS)

    Stacey, J. M.

    1987-01-01

    Microwave fluxes from three quiet seas documented for five microwave frequencies. Measurements taken by satellite in Earth orbit with mechanically scanned antenna. 10-channel receiver used to record simultaneously signal intensities in both horizontal and vertical polarizations at each frequency. Comparisons of flux measurements of three quiet seas drawn, and results discussed and analyzed.

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

    PubMed

    Conesa, J

    1995-06-01

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

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

    PubMed

    Conesa, J

    1995-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  6. Coherent structure in solar wind C{sup 6+}/C{sup 4+} ionic composition data during the quiet-sun conditions of 2008

    SciTech Connect

    Edmondson, J. K.; Lepri, S. T.; Zurbuchen, T. H.; Lynch, B. J.

    2013-11-20

    This analysis offers evidence of characteristic scale sizes in solar wind charge state data measured in situ for 13 quiet-Sun Carrington rotations in 2008. Using a previously established novel methodology, we analyze the wavelet power spectrum of the charge state ratio C{sup 6+}/C{sup 4+} measured in situ by ACE/SWICS for 2 hr and 12 minute cadence. We construct a statistical significance level in the wavelet power spectrum to quantify the interference effects arising from filling missing data in the time series, allowing extraction of significant power from the measured data to a resolution of 24 minutes. We analyze each wavelet power spectrum for transient coherency and global periodicities resulting from the superposition of repeating coherent structures. From the significant wavelet power spectra, we find evidence for a general upper limit on individual transient coherency of ∼10 days. We find evidence for a set of global periodicities between 4-5 hr and 35-45 days. We find evidence for the distribution of individual transient coherency scales consisting of two distinct populations. Below the ∼2 day timescale, the distribution is reasonably approximated by an inverse power law, whereas for scales ≳2 days, the distribution levels off, showing discrete peaks at common coherency scales. In addition, by organizing the transient coherency scale distributions by wind type, we find that these larger, common coherency scales are more prevalent and well defined in coronal hole wind. Finally, we discuss the implications of our results for current theories of solar wind generation and describe future work for determining the relationship between the coherent structures in our ionic composition data and the structure of the coronal magnetic field.

  7. The QUIET Instrument

    SciTech Connect

    Bischoff, C.; et al.

    2012-07-01

    The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ({approx}1{sup o}). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 {mu}Ks{sup 1/2}) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0:1. The 84-element W-band polarimeter array has a sensitivity of 87 {mu}Ks{sup 1/2} at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0:01. The two arrays together cover multipoles in the range {ell} {approx} 25 -- 975. These are the largest HEMT-based arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument.

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

    NASA Astrophysics Data System (ADS)

    Etoundi Messanga, Honoré

    2015-04-01

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

  9. Quiet powered-lift propulsion

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Latest results of programs exploring new propulsion technology for powered-lift aircraft systems are presented. Topics discussed include results from the 'quiet clean short-haul experimental engine' program and progress reports on the 'quiet short-haul research aircraft' and 'tilt-rotor research aircraft' programs. In addition to these NASA programs, the Air Force AMST YC 14 and YC 15 programs were reviewed.

  10. Quiet time enhancements over African latitudes

    NASA Astrophysics Data System (ADS)

    Orford, Nicola; Katamzi, Zama; Buresova, Dalia

    2016-07-01

    F2 layer disturbances not related to geomagnetic activity are known as quiet time enhancements (QTEs). The phenomenon of QTEs has not yet been studied over African latitudes. We therefore explore the occurrence of QTEs over Africa in order to expand our knowledge on the behaviour of the ionosphere over this region. Several GPS stations in the middle to equatorial latitudes, during the solar minimum (2009) and near solar maximum (2013), are used. This data was examined for possible trends in variation with solar cycle, season and latitude as well as time of commencement of enhancements. Over the southern mid-latitude region of Africa we have observed that the QTEs are more likely to commence during the night in both solar minimum and maximum, however a slightly larger portion of daytime commencements during solar minimum than during solar maximum were observed. The total number of enhancements for the solar minimum period appears greater than during solar maximum. A seasonal trend is seen with the maximum number of enhancements occurring in summer during solar minimum and in winter during solar maximum. We explore further whether these trends are mirrored or different at low latitude/equatorial African regions.

  11. Quiet High-Speed Fan

    NASA Technical Reports Server (NTRS)

    Lieber, Lysbeth; Repp, Russ; Weir, Donald S.

    1996-01-01

    A calibration of the acoustic and aerodynamic prediction methods was performed and a baseline fan definition was established and evaluated to support the quiet high speed fan program. A computational fluid dynamic analysis of the NASA QF-12 Fan rotor, using the DAWES flow simulation program was performed to demonstrate and verify the causes of the relatively poor aerodynamic performance observed during the fan test. In addition, the rotor flowfield characteristics were qualitatively compared to the acoustic measurements to identify the key acoustic characteristics of the flow. The V072 turbofan source noise prediction code was used to generate noise predictions for the TFE731-60 fan at three operating conditions and compared to experimental data. V072 results were also used in the Acoustic Radiation Code to generate far field noise for the TFE731-60 nacelle at three speed points for the blade passage tone. A full 3-D viscous flow simulation of the current production TFE731-60 fan rotor was performed with the DAWES flow analysis program. The DAWES analysis was used to estimate the onset of multiple pure tone noise, based on predictions of inlet shock position as a function of the rotor tip speed. Finally, the TFE731-60 fan rotor wake structure predicted by the DAWES program was used to define a redesigned stator with the leading edge configured to minimize the acoustic effects of rotor wake / stator interaction, without appreciably degrading performance.

  12. Geomagnetic Workshop, Canberra

    NASA Astrophysics Data System (ADS)

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

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

  13. Snowstorm at the geomagnetic observatory

    NASA Astrophysics Data System (ADS)

    Čop, R.

    2015-08-01

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

  14. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Namgaladze, A. A.; Förster, M.; Yurik, R. Y.

    2000-04-01

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

  16. The geomagnetic tail

    SciTech Connect

    Birn, J. )

    1991-01-01

    A review is presented of the plasma sheet and lobe regions of the magnetotail, focusing principally on large-scale processes or microprocesses with some large-scale effects. Consideration is given to quiet and average structures, not necessarily related to activity phases, with quasi-steady convection aspects, and with the characteristics of dynamic phases including acceleration mechanisms and single particle aspects. Attention is given to various activity models, average and quiet time properties, properties and effects of magnetospheric convection, dynamics of the magnetotail, and the near tail, substorm current wedge.

  17. Effect of Repeated Exposures on Word Learning in Quiet and Noise

    ERIC Educational Resources Information Center

    Blaiser, Kristina M.; Nelson, Peggy B.; Kohnert, Kathryn

    2015-01-01

    This study examines the impact of repeated exposures on word learning of preschool children with and without hearing loss (HL) in quiet and noise conditions. Participants were 19 children with HL and 17 peers with normal hearing (NH). Children were introduced to 16 words: 8 in quiet and 8 in noise conditions. Production and identification scores…

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

    NASA Astrophysics Data System (ADS)

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

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

  19. A triumph of quiet diplomacy

    SciTech Connect

    Keeny, S.M. Jr.

    1994-11-01

    The new US agreement with North Korea is a breakthrough in the international effort to eliminate the most serious threat to the non-proliferation regime. Despite mutual mistrust, the two sides have, by quiet diplomacy, crafted an ingenious agreement that terminates Pyongyang`s current and future nuclear weapons program in return for economic benefits and an opportunity to join the international community.

  20. Looking for Peace and Quiet

    ERIC Educational Resources Information Center

    Palin, Ray

    2014-01-01

    Ray Palin, librarian at Sunapee Middle High School in Sunapee, New Hampshire describes what it takes to make the school library a space for those looking for "peace and quiet." Palin begins this article by noting that much has been written about the advantages associated with the learning commons model of library design, however less has…

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

    SciTech Connect

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

    1981-05-01

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

  2. Introduction to Geomagnetic Fields

    NASA Astrophysics Data System (ADS)

    Hinze, William J.

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

  3. Testing the magnetotail configuration based on observations of low-altitude isotropic boundaries during quiet times

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Ganushkina, N.; Toth, G.; Dubyagin, S.; Liemohn, M. W.

    2015-12-01

    We investigate the configuration of the geomagnetic field on the nightside magnetosphere during a quiet time interval based on National Oceanic and Atmospheric Administration Polar Orbiting Environment Satellites Medium Energy Proton and Electron Detector (NOAA/POES MEPED) measurements in combination with numerical simulations of the global terrestrial magnetosphere using the Space Weather Modeling Framework. Measurements from the NOAA/POES MEPED low-altitude data sets provide the locations of isotropic boundaries; those are used to extract information regarding the field structure in the source regions in the magnetosphere. In order to evaluate adiabaticity and mapping accuracy, which is mainly controlled by the ratio between the radius of curvature and the particle's Larmor radius, we tested the threshold condition for strong pitch angle scattering based on the MHD magnetic field solution. The magnetic field configuration is represented by the model with high accuracy, as suggested by the high correlation coefficients and very low normalized root-mean-square errors between the observed and the modeled magnetic field. The scattering criterion, based on the values of k=Rcρ ratio at the crossings of magnetic field lines, associated with isotropic boundaries, with the minimum B surface, predicts a critical value of kCR˜33. This means that, in the absence of other scattering mechanisms, the strong pitch angle scattering takes place whenever the Larmor radius is ˜33 times smaller than the radius of curvature of the magnetic field, as predicted by the Space Weather Modeling Framework.

  4. Noise in the quiet zone

    NASA Astrophysics Data System (ADS)

    Cronin, M.; Tauxe, L.; Constable, C.; Selkin, P.; Pick, T.

    2001-07-01

    We have carried out a detailed paleomagnetic investigation of two stratigraphically overlapping sections from the Scaglia Bianca Formation (˜85-89.5 Ma) in the Umbria-Marche area in central Italy. Sampling was conducted over 32 m and 7 m intervals at La Roccaccia and Furlo respectively. After AF cleaning the majority of specimens show the expected normal magnetic field orientation, however a number of specimens are directionally anomalous. Some of these deviant specimens are accompanied by apparent spikes or dips in normalized intensity. A detailed investigation of rock magnetics shows that most of these deviations are not a sign of excursionary geomagnetic field behavior, but rather correspond to specimens with distinct rock magnetic characteristics and are therefore rock magnetic 'noise'. Such specimens should not be interpreted as records of the geomagnetic field. Our experience suggests that detailed rock magnetic and magnetic fabric analysis should be done on all anomalous directions prior to interpreting them as geomagnetic field behavior. After elimination of rock magnetic noise in the Scaglia Bianca data sets, there is a high degree of agreement in direction and to a lesser extent relative intensity between correlative portions of the two sections. We therefore offer this data set as a robust record of geomagnetic field behavior during the 4.5 Myr interval represented by the La Roccaccia section. A statistical analysis of the relative intensity observations suggests that this period of the Cretaceous Normal Superchron is characterized by a normalized variability in paleointensity (standard deviation about 28% of the mean value) that is significantly lower than seen during the Oligocene over intervals in which reversals or tiny wiggles occur (typically about 50%). The directional stability results in virtual geomagnetic pole dispersion compatible with that found in volcanic rocks from around the same latitude and ranging in age from 80 to 110 Ma.

  5. A Quiet Transformation

    ERIC Educational Resources Information Center

    Dierke, James S.

    2012-01-01

    The author's 40 years as an educator have led him to an important insight: stress is crippling the schools. On top of other extreme conditions in schools and on students, there is the pressure to achieve and succeed in a fast-paced, chaotic world. This pervasive stress compromises the physical health, and in turn the cognitive and psychological…

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    PubMed

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

    2014-08-01

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

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

    PubMed

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

    2014-08-01

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

  9. Tsunami related to solar and geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2016-04-01

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

  10. Solar and geomagnetic trends of equatorial evening and nighttime F region vertical ion drifts

    NASA Astrophysics Data System (ADS)

    Oyekola, O. S.; Oluwafemi, C. O.

    2008-12-01

    F region vertical ion drifts were inferred from the evening and nighttime ionosonde data for two magnetic equatorial stations in West Africa: Ouagadougou (geographic: 12°N, 1.5°W; 5.9°N dip) and Ibadan (geographic: 7.9°N, 3.9°E; 6°S dip). We examine and discuss the short-term patterns of behavior of ionospheric variability over Ouagadougou for 1986-1987 years of low solar activity (F10.7 = 80) and 1988-1989 years of high solar activity (F10.7 = 180) for quiet time, while that of Ibadan is for undisturbed (Kp ≤ 3.0) and disturbed (Kp > 3.0) geomagnetic conditions during the 1958 International Geophysical Year (IGY) period, corresponding to high solar flux conditions (F10.7 = 208). Our results indicate that the evening and nighttime ion drift exhibits strong variations with the phase of the solar cycle but only small variations with geomagnetic activity. The characteristic values of evening prereversal velocity enhancements (PRE) vary between about 2-14 m/s and 12-22 m/s and 17-42 m/s and 18-40 m/s for low and high solar flux, unperturbed and perturbed conditions, in that order. The solar minimum evening reversal times are strongly season dependent, while the morning reversal times are season independent except during December solstice, which occurs earliest. During solar maximum, reversal times near dawn and dusk are essentially season independent except during June solstice season, which occurs late. The average occurrence time (1900 LT) of PRE is strongly independent of solar and magnetic variations apart from June solstice of high solar activity periods.

  11. Foundations of Geomagnetism

    NASA Astrophysics Data System (ADS)

    Jackson, Andy

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

  12. Mid-latitude Geomagnetic Field Analysis Using BOH Magnetometer: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Hwang, Jun-Ga; Choi, Kyu-Cheol; Lee, Jae-Jin; Park, Young-Deuk; Ha, Dong-Hun

    2011-09-01

    Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Mt. Bohyun Observatory to measure the Earth's magnetic field variations in South Korea. We, in 2007, installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we provide the preliminary and the first statistical analysis using the BOH magnetometer installed at Mt. Bohyun Observatory. By superposed analysis, we find that daily variations of H, D, and Z shows similar tendency, that is, about 30 minutes before the meridian (11:28) a minimum appears and the time after about 3 hours and 30 minutes (15:28) a maximum appears. Also, a quiet interval start time (19:06) is near the sunset time, and a quiet interval end time (06:40) is near the sunrise time. From the sunset to the sunrise, the value of H has a nearly constant interval, that is, the sun affects the changes in H values. Seasonal variations show similar dependences to the sun. Local time variations show that noon region has the biggest variations and midnight region has the smallest variations. We compare the correlations between geomagnetic variations and activity indices as we expect the geomagnetic variation would contain the effects of geomagnetic activity variations. As a result, the correlation coefficient between H and Dst is the highest (r = 0.947), and other AL, AE, AU index and showed a high correlation. Therefore, the effects of geomagnetic storms and geomagnetic substorms might contribute to the geomagnetic changes significantly.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  14. On regional geomagnetic charts

    USGS Publications Warehouse

    Alldredge, L.R.

    1987-01-01

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

  15. Geomagnetism. Volume I

    SciTech Connect

    Jacobs, J.A.

    1987-01-01

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

  16. On extreme geomagnetic storms

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  17. Spiking the Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Constable, C.; Davies, C. J.

    2015-12-01

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

  18. Geomagnetic referencing in the arctic environment

    USGS Publications Warehouse

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

    2011-01-01

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

  19. Geomagnetic referencing in the arctic environment

    USGS Publications Warehouse

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

    2011-01-01

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

  20. [The dynamics of pulse rate and biochemical parameters in blood of healthy individuals in relation to Pc5-6 geomagnetic pulsations].

    PubMed

    Zenchenko, T A; Medvedeva, A A; Potolitsyna, N N; Parshukova, O I; Boiko, E R

    2015-01-01

    Four experiments on long-term monitoring of pulse rate and blood biochemical parameters in four healthy volunteers (women) were conducted. The duration of each experiment was 90 minutes, electrocardiography was performed continuously, taking blood sampling every two minutes. In venous blood the current concentrations of triiodothyronine, cortisol, glucose, stable metabolites of nitrogen oxides (NO(x)) were determined. Synchronicity in oscillations of cortisol and free triiodothyronine levels in the blood of all four volunteers was detected, as well as the presence of the periods of 7-8 min and 15-17 min in the spectra of these biochemical parameters was observed. The periods in the spectra of NO(x) are equal to 7 min, 13 min and 25-30 min. It is shown that the, dynamics of variations in the heart rate is determined mostly by the rhythms of fluctuations in the level of NO(x) in the blood, and the periods in wavelet spectra of these physiological parameters in all four volunteers are close to the periods of their spectra synchronous variations of a. geomagnetic field vector in the frequency range of 0.5-3 mHz. The results obtained in this study indicate that. the presence of nitric oxide and its metabolites in the blood is a biochemical factor, with high probability of its participation in the developmental process of the fine "tuning" of the body to the variations of the geomagnetic field providing synchronization of variations in heart rate and geomagnetic fluctuations in the geomagnetic quiet conditions. PMID:26016037

  1. The national geomagnetic initiative

    NASA Technical Reports Server (NTRS)

    1993-01-01

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

  2. Quantifying the quiet epidemic

    PubMed Central

    2014-01-01

    During the late 20th century numerical rating scales became central to the diagnosis of dementia and helped transform attitudes about its causes and prevalence. Concentrating largely on the development and use of the Blessed Dementia Scale, I argue that rating scales served professional ends during the 1960s and 1970s. They helped old age psychiatrists establish jurisdiction over conditions such as dementia and present their field as a vital component of the welfare state, where they argued that ‘reliable modes of diagnosis’ were vital to the allocation of resources. I show how these arguments appealed to politicians, funding bodies and patient groups, who agreed that dementia was a distinct disease and claimed research on its causes and prevention should be designated ‘top priority’. But I also show that worries about the replacement of clinical acumen with technical and depersonalized methods, which could conceivably be applied by anyone, led psychiatrists to stress that rating scales had their limits and could be used only by trained experts. PMID:25866448

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

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Gu, X. Y.

    1986-01-01

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

  4. Remote Observations of Ion Temperatures in the Quiet Time Magnetosphere

    NASA Technical Reports Server (NTRS)

    Keesee, A. M.; Buzulukova, N.; Goldstein, J.; McComas, D. J.; Scime, E. E.; Spence, H.; Fok, M. C.; Tallaksen, K.

    2011-01-01

    Ion temperature analysis of the first energetic neutral atom images of the quiet -time, extended magnetosphere provides evidence of multiple regions of ion heating. This study confirms the existence of a dawn -dusk asymmetry in ion temperature predicted for quiescent magnetospheric conditions by Spence and Kivelson (1993) and demonstrates that it is an inherent magnetospheric feature.

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

    SciTech Connect

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

    1992-05-01

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

  6. Lower thermosphere densities of N2, O and Ar under high latitude winter conditions

    NASA Technical Reports Server (NTRS)

    Dickinson, P. H. G.; Vonzahn, U.; Baker, K. D.; Jenkins, D. B.

    1986-01-01

    Measurements of the neutral thermosphere were conducted in northern Scandinavia during the Energy Budget Campaign. These measurements included determinations of N2, O, and Ar densities using rocket-borne experiments. The results obtained in the experiments are presented, taking into account also details regarding the employed experimental methods, and an evaluation of the significance of the data. It is found that there are striking differences in thermospheric distributions of the neutral constituents under different geomagnetic conditions. Under quiet geomagnetic conditions there was reasonable agreement with the United States Standard Atmosphere. The concentrations of N2 and Ar were about 70 percent of the predicted values, while the O concentration was about 2.5 times greater.

  7. Hazards of geomagnetic storms

    USGS Publications Warehouse

    Herzog, D.C.

    1992-01-01

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

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

    PubMed

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

    2014-02-01

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

  9. Quiet-time observation of a coherent compressional Pc-4 micropulsation at synchronous altitude

    NASA Technical Reports Server (NTRS)

    Paulikas, G. A.; Schulz, M.; Barfield, J. N.; Lanzerotti, L. J.; Maclennan, C. G.

    1971-01-01

    During a magnetically quiet interval the magnetic-field intensity and energetic electron fluxes at ATS 1 exhibited coherent modulations having a frequency of 33.8 cph and a duration of approximately 40 oscillations. The electron fluxes and the magnetic field oscillated in phase. The field perturbation reached 8 jamma (peak to peak) in the direction of the unperturbed geomagnetic field. The transverse component of the field perturbation was practically zero. The characteristics of the observed oscillations appear compatible with those of a compressional excitation of the outer magnetosphere. The substantially radial normal mode is perhaps driven by a bounce-resonant interaction with the 15-keV protons that populate the quiet-day ring current.

  10. Human physiological reaction to geomagnetic disturbances of solar origin

    NASA Astrophysics Data System (ADS)

    Dimitrova, Sv.; Stoilova, I.

    2002-12-01

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

  11. Solar quiet day ionospheric source current in the West African region

    NASA Astrophysics Data System (ADS)

    Obiekezie, Theresa N.; Okeke, Francisca N.

    2013-05-01

    The Solar Quiet (Sq) day source current were calculated using the magnetic data obtained from a chain of 10 magnetotelluric stations installed in the African sector during the French participation in the International Equatorial Electrojet Year (IEEY) experiment in Africa. The components of geomagnetic field recorded at the stations from January-December in 1993 during the experiment were separated into the source and (induced) components of Sq using Spherical Harmonics Analysis (SHA) method. The range of the source current was calculated and this enabled the viewing of a full year's change in the source current system of Sq.

  12. Solar quiet day ionospheric source current in the West African region.

    PubMed

    Obiekezie, Theresa N; Okeke, Francisca N

    2013-05-01

    The Solar Quiet (Sq) day source current were calculated using the magnetic data obtained from a chain of 10 magnetotelluric stations installed in the African sector during the French participation in the International Equatorial Electrojet Year (IEEY) experiment in Africa. The components of geomagnetic field recorded at the stations from January-December in 1993 during the experiment were separated into the source and (induced) components of Sq using Spherical Harmonics Analysis (SHA) method. The range of the source current was calculated and this enabled the viewing of a full year's change in the source current system of Sq. PMID:25685434

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  14. Smart materials for turbomachinery quieting

    NASA Astrophysics Data System (ADS)

    Jonson, Michael L.; Lysak, Peter D.; Willits, Steven M.

    2000-06-01

    As part of the Defense Advanced Research Projects Agency (DARPA) SAMPSON program, a team has been developing and testing the use of smart materials for quieting turbomachinery. The team is composed of representatives form Pennsylvania State University, General Dynamics Electric Boat, GTE BBN Technologies, and the Naval Surface Warfare Center Carderock Division. Four concepts for quieting were proposed and wind tunnel testing, water tunnel testing, as well as computational fluid dynamic analysis were performed to down select two of the concepts for further consideration: protuberance and gap control. The wind tunnel testing was performed to determine the optimum shape of the protuberance. Water tunnel testing was performed at Penn State University/Applied Research Laboratory to establish the performance of the protuberance and gap control elements. Piezoelectric inchworm actuators, developed by PSU/Center for Acoustics and Vibration, were utilized for the evaluation of the two concepts. GTE BBN Technologies developed the control system simulation for the ultimate concept, the General Dynamics Electric Boat was responsible for hydrodynamic and hydroacoustic analysis. Naval Surface Warfare Center/Carderock Division performed hydrodynamic analysis and developed the rotary component design for the water tunnel test fixture. Successful testing in the twelve- inch diameter water tunnel at PSU/ARL demonstrated superior performance with the gap control concept over the protuberance control concept, and efforts are on-going to develop the final large scale demonstration. This paper summarizes the result of these activities.

  15. Spherical harmonic representation of the main geomagnetic field for world charting and investigations of some fundamental problems of physics and geophysics

    NASA Technical Reports Server (NTRS)

    Barraclough, D. R.; Hide, R.; Leaton, B. R.; Lowes, F. J.; Malin, S. R. C.; Wilson, R. L. (Principal Investigator)

    1981-01-01

    The data processing of MAGSAT investigator B test tapes and data tapes, and tapes of selected data on 15 magnetically quiet days is reported. The 1980 World Chart spherical model was compared with the MAGSAT (3/80) and MAGSAT vector data were used in the models. An article on modelling the geomagnetic field using satellite data is included.

  16. Alternating light-darkness-influenced human electrocardiographic magnetoreception in association with geomagnetic pulsations.

    PubMed

    Otsuka, K; Oinuma, S; Cornélissen, G; Weydahl, A; Ichimaru, Y; Kobayashi, M; Yano, S; Holmeslet, B; Hansen, T L; Mitsutake, G; Engebretson, M J; Schwartzkopff, O; Halberg, F

    2001-01-01

    December 10, 1998, and November 2, 2000, on 19 clinically healthy subjects, 21 to 54 years of age, in Alta, Norway. A geomagnetic record was obtained from the Auroral Observatory of the University of Tromsø. First, frequency-domain measures of HRV were compared for each person in 24-hour spans of high geomagnetic disturbance versus quiet conditions. Second, cross-spectra between geomagnetic activity and HRV measures were quantified via the squared coherence spectrum using 7-day time series. A 7.5% increase in the 24-hour average of heart rate, HR (P = 0.00020) and a decrease in HRV were documented on days of high geomagnetic disturbance. The decrease in HRV was validated statistically for the 'total frequency', 'TF' endpoint (18.6% decrease, P= 0.00009). The decrease in spectral power was found primarily in the 'circaminutan frequency', 'VLF' (21.9% decrease, P< 0.000001) in conjunction with the 'minutes-to-hours' component, ultra-low-frequency, 'ULF' (15.5% decrease, P= 0.00865) and circadecasecundan 'low frequency', 'LF' (14.2% decrease, P = 0.00187) regions of the spectrum. Power-law scaling of the power spectra did not show any statistically significant difference. It is noteworthy that most of the decrease in HRV, except for the circaminutan (VLF) component, was observed only in the season in which sunshine alternated with darkness (D/L), a finding suggesting a mechanism influenced by the alternation of light and darkness. The hypothesis of a light-dark-influenced magnetoreception was also supported by cross-spectral analysis. Group-averaged coherence at frequencies coincident with the geomagnetic Pc 6 pulsations (with periods ranging from 10 minutes to 5 hours) differed with a statistical significance (P < 0.000001) among the three natural lighting conditions, the association being weaker during UL or D/D than during D/L. By contrast, no statistically significant differences were found in terms of the circadian and circasemidian frequencies in relation to the

  17. Studies Highlight Classroom Plight of Quiet Students

    ERIC Educational Resources Information Center

    Sparks, Sarah D.

    2012-01-01

    Educators often look for ways to bring quiet children out of their shells, but emerging research suggests schools can improve academic outcomes for introverted students by reducing the pressure to be outgoing and giving all students a little more time to reflect. A 2011 study found teachers from across K-12 rated hypothetical quiet children as…

  18. A Quiet Place for Student Veterans

    ERIC Educational Resources Information Center

    Hollingsworth, Margaret

    2015-01-01

    As electronic gadgets predominate a student's life, there comes a need for silence. A quiet place free of electromagnetic spectrum waves, dirty and stray electricity, and the endless chirps, whistles, beeps, and customized signaling. A quiet place can offer solitude for meditation, inspiration, and spiritual awareness. Student involvement in the…

  19. Bracing for the geomagnetic storms

    SciTech Connect

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

    1990-03-01

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

  20. Bayesian inference in geomagnetism

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    USGS Publications Warehouse

    Campbell, W.H.

    1981-01-01

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

  4. The Birkland Currents, the Electrojets, Auroral Precipitation, Intense Electric Field Channels, and the Open-Closed Field Line Boundary: A Synthesis of Quiet Time Auroral Current Structure Near the Harang Discontinuity.

    NASA Astrophysics Data System (ADS)

    Archer, W. E.; Knudsen, D. J.; Burchill, J. K.; Jackel, B. J.; Donovan, E.; Spanswick, E.; Connors, M. G.

    2015-12-01

    The European Space Agency Swarm satellite mission began with all three Swarm satellites in similar, noon-to-midnight polar orbits. We present electric field, magnetic field, electron density, electron temperature, and ion temperature measurements from early in the Swarm mission (December 2013). This data set is of particular interest as the pearls-on-a-string orientation of the satellites provide multiple measurements of similar volumes of space taken minutes apart, providing confidence in measurement integrity and reducing the spatio-temporal ambiguity inherent to in-situ measurements. Furthermore, the measurement period is characterized by low geomagnetic activity which results in consistent measurement conditions orbit to orbit. The December 2013 ionospheric Swarm measurements combined with ground-based optical and magnetic measurements provide a consistent picture of ionospheric and field-aligned currents near midnight during quiet geomagnetic conditions. Relationships between large-scale field aligned currents, auroral precipitation, narrow regions of enhanced electric fields, the electrojets, and the open-closed field line boundary have all been studied pairwise previously. We present a synthesis interpretation of the set of measurements to arrive at a consistent picture of the auroral current structure near midnight. This work is supported by a grant from the Canadian Space Agency.

  5. Geomagnetic Reversals during the Phanerozoic.

    PubMed

    McElhinny, M W

    1971-04-01

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

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

    PubMed

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

    2013-03-01

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

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

    PubMed

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

    2013-03-01

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

  8. A quiet ego quiets death anxiety: humility as an existential anxiety buffer.

    PubMed

    Kesebir, Pelin

    2014-04-01

    Five studies tested the hypothesis that a quiet ego, as exemplified by humility, would buffer death anxiety. Humility is characterized by a willingness to accept the self and life without comforting illusions, and by low levels of self-focus. As a consequence, it was expected to render mortality thoughts less threatening and less likely to evoke potentially destructive behavior patterns. In line with this reasoning, Study 1 found that people high in humility do not engage in self-serving moral disengagement following mortality reminders, whereas people low in humility do. Study 2 showed that only people low in humility respond to death reminders with increased fear of death, and established that this effect was driven uniquely by humility and not by some other related personality trait. In Study 3, a low sense of psychological entitlement decreased cultural worldview defense in response to death thoughts, whereas a high sense of entitlement tended to increase it. Study 4 demonstrated that priming humility reduces self-reported death anxiety relative to both a baseline and a pride priming condition. Finally, in Study 5, experimentally induced feelings of humility prevented mortality reminders from leading to depleted self-control. As a whole, these findings obtained from relatively diverse Internet samples illustrate that the dark side of death anxiety is brought about by a noisy ego only and not by a quiet ego, revealing self-transcendence as a sturdier, healthier anxiety buffer than self-enhancement.

  9. Monitoring of the mass density profile along the 0° geomagnetic longitude during magnetic storms with the use of ground magnetometers.

    NASA Astrophysics Data System (ADS)

    Romanova, N.; Stepanova, M. V.; Kozyreva, O. V.; Pilipenko, V.; Zesta, E.

    2015-12-01

    Ground magnetometers offer a very cheap and robust means of globally monitoring the magnetospheric mass density, by determining the ULF field line resonant frequency. ULF waves are almost always present in near-Earth environment and are generated by the solar wind interaction with the terrestrial magnetosphere. These waves from the magnetopause propagate through the magnetosphere. When they encounter a field line that resonates at the same frequency, coupling to the Alfven field line oscillations occurs and the resonance can be detected on the ground at that particular latitude. There are different methods for determining resonant frequencies from ground ULF waves. the density profiles along the 0° geomagnetic longitude were obtained using both the gradient and the amplitude-phase methods for the analysis of the magnetic field data from the magnetometer arrays: SAMBA (South American Meridional B-field Array), MAGDAS and American Antarctic bases (Palmer, WAIS-D). We compared the density profiles during quiet magnetic conditions and during strong magnetic storms (recovery phase). It is shown that in the recovery phase of strong magnetic storms (Dst <-150 nT) profile of the equatorial mass density varies greatly in comparison with the density distribution in quiet days.

  10. Prognostic Analysis of the Tactical Quiet Generator

    SciTech Connect

    Hively, Lee M

    2008-09-01

    The U.S. Army needs prognostic analysis of mission-critical equipment to enable condition-based maintenance before failure. ORNL has developed and patented prognostic technology that quantifies condition change from noisy, multi-channel, time-serial data. This report describes an initial application of ORNL's prognostic technology to the Army's Tactical Quiet Generator (TQG), which is designed to operate continuously at 10 kW. Less-than-full power operation causes unburned fuel to accumulate on internal components, thereby degrading operation and eventually leading to failure. The first objective of this work was identification of easily-acquired, process-indicative data. Two types of appropriate data were identified, namely output-electrical current and voltage, plus tri-axial acceleration (vibration). The second objective of this work was data quality analysis to avoid the garbage-in-garbage-out syndrome. Quality analysis identified more than 10% of the current data as having consecutive values that are constant, or that saturate at an extreme value. Consequently, the electrical data were not analyzed further. The third objective was condition-change analysis to indicate operational stress under non-ideal operation and machine degradation in proportion to the operational stress. Application of ORNL's novel phase-space dissimilarity measures to the vibration power quantified the rising operational stress in direct proportion to the less-than-full-load power. We conclude that ORNL's technology is an excellent candidate to meet the U.S. Army's need for equipment prognostication.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  12. The Lewis Research Center geomagnetic substorm simulation facility

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  13. a Millennium of Geomagnetism

    NASA Astrophysics Data System (ADS)

    Stern, David P.

    2002-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  15. The 'Love Hormone' May Quiet Tinnitus

    MedlinePlus

    ... medlineplus.gov/news/fullstory_161110.html The 'Love Hormone' May Quiet Tinnitus Small, preliminary study suggests oxytocin ... tinnitus -- may find some relief by spraying the hormone oxytocin in their nose, a small initial study ...

  16. Supersonic quiet-tunnel development for laminar-turbulent transition research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1995-01-01

    This grant supported research into quiet-flow supersonic wind-tunnels, between February 1994 and February 1995. Quiet-flow nozzles operate with laminar nozzle-wall boundary layers, in order to provide low-disturbance flow for studies of laminar-turbulent transition under conditions comparable to flight. Major accomplishments include: (1) development of the Purdue Quiet-Flow Ludwieg Tube, (2) computational evaluation of the square nozzle concept for quiet-flow nozzles, and (3) measurement of the presence of early transition on the flat sidewalls of the NASA LaRC Mach 3.5 supersonic low-disturbance tunnel. Since items (1) and (2) are described in the final report for companion grant NAG1-1133, only item (3) is described here. A thesis addressing the development of square nozzles for high-speed, low-disturbance wind tunnels is included as an appendix.

  17. Secular trend of geomagnetic elements in the Indian region

    NASA Astrophysics Data System (ADS)

    Bhardwaj, S. K.; Subba Rao, P. B. V.

    2013-12-01

    In the present study, secular trends and jerks in the geomagnetic elements D, H and Z are investigated at the six Indian magnetic observatories using annual and monthly mean values for all days, quiet days and night base (night time mean). The residuals of all-day annual and monthly means are computed by removing a polynomial fit from their best fitting curves. The residuals of D, H and Z curves do not show any parallelism with the 11-year sunspot cycle. At Alibag, the D residual shows a periodicity of 2 solar cycles, whereas the H and Z residuals indicate a quasi-periodicity of 3 solar cycles for the period 1921-2009. At the Indian stations, an in-phase solar cycle component is observed for 2 of the solar cycles in the D and Z residuals, while the H residual shows out-of-phase variations with the sunspot cycle for the period 1958-2009. Two geomagnetic jerks, 1970 and 1991, are well reflected in the monthly and annual mean values in the Indian region, as observed globally.

  18. Forbush decreases geomagnetic and atmospheric effects cosmogenic nuclides

    NASA Technical Reports Server (NTRS)

    Flueckiger, E. O.

    1986-01-01

    An overview and synthesis is given of recent developments that have occurred in the areas of Forbush decreases, geomagnetic and atmospheric effects, and cosmogenic nuclides. Experimental evidence has been found for substantial differences in the effects of the various types of interplanetary perturbations on cosmic rays, and for a dependence of these effects on the three-dimensional configuration of the interplanetary medium. In order to fully understand and to be able to simulate the solar cosmic ray particle access to the polar regions of the earth we need accurate models of the magnetospheric magnetic field. These models must include all major magnetospheric current systems (in particular the field aligned currents), and they should represent magnetically quiet time periods as well as different levels of geomagnetic activity. In the evolution of magnetospheric magnetic field models, cosmic ray and magnetospheric physicists should work closely together since cosmic ray measurements are a powerful additional tool in the study of the perturbed magnetosphere. In the field of cosmogenic nuclides, finally, exciting new results and developments follow in rapid succession. Thanks to new techniques and new isotopes the analysis of cosmic ray history has entered into a new dimension.

  19. Overview of the Arizona Quiet Pavement Program

    NASA Astrophysics Data System (ADS)

    Donavan, Paul; Scofield, Larry

    2005-09-01

    The Arizona Quiet Pavement Pilot Program (QP3) was initially implemented to reduce highway related traffic noise by overlaying most of the Phoenix metropolitan area Portland cement concrete pavement with a one inch thick asphalt rubber friction coarse. With FHWA support, this program represents the first time that pavement surface type has been allowed as a noise mitigation strategy on federally funded projects. As a condition of using pavement type as a noise mitigation strategy, ADOT developed a ten-year, $3.8 million research program to evaluate the noise reduction performance over time. Historically, pavement surface type was not considered a permanent solution. As a result, the research program was designed to specifically address this issue. Noise performance is being evaluated through three means: (1) conventional roadside testing within the roadway corridor (e.g., far field measurements within the right-of-way) (2) the use of near field measurements, both close proximity (CPX) and sound intensity (SI); and (3) far field measurements obtained beyond the noise barriers within the surrounding neighborhoods. This paper provides an overview of the program development, presents the research conducted to support the decision to overlay the urban freeway, and the status of current research.

  20. Long periods (1 -10 mHz) geomagnetic pulsations variation with solar cycle in South Atlantic Magnetic Anomaly

    NASA Astrophysics Data System (ADS)

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

    The occurrence and intensity of the geomagnetic pulsations Pc-5 (2-7 mHz) and its relationship with the solar cycle in the South Atlantic Magnetic Anomaly -SAMA is presented. The study of geomagnetic pulsations is important to help the understanding of the physical processes that occurs in the magnetosphere region and help to predict geomagnetic storms. The fluxgate mag-netometers H, D and Z, three axis geomagnetic field data from the Southern Space Observatory -SSO/CRS/INPE -MCT, São Martinho da Serra (29.42° S, 53.87° W, 480m a.s.l.), RS, Brasil, a were analyzed and correlated with the solar wind parameters (speed, density and temperature) from the ACE and SOHO satellites. A digital filtering to enhance the 2-7 mHz geomagnetic pulsations was used. Five quiet days and five perturbed days in the solar minimum and in the solar maximum were selected for this analysis. The days were chosen based on the IAGA definition and on the Bartels Musical Diagrams (Kp index) for 2001 (solar maximum) and 2008 (solar minimum). The biggest Pc-5 amplitude averages differences between the H-component is 78,35 nT for the perturbed days and 1,60nT for the quiet days during the solar maximum. For perturbed days the average amplitude during the solar minimum is 8,32 nT, confirming a direct solar cycle influence in the geomagnetic pulsations intensity for long periods.

  1. Development of quiet-flow supersonic wind tunnels for laminar-turbulent transition research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven P.

    1994-01-01

    This grant supported research into quiet-flow supersonic wind-tunnels, between May 1990 and December 1994. Quiet-flow nozzles operate with laminar nozzle-wall boundary layers, in order to provide low-disturbance flow for studies of laminar-turbulent transition under conditions comparable to flight. Major accomplishments include: (1) the design, fabrication, and performance-evaluation of a new kind of quiet tunnel, a quiet-flow Ludweig tube; (2) the integration of preexisting codes for nozzle design, 2D boundary-layer computation, and transition-estimation into a single user-friendly package for quiet-nozzle design; and (3) the design and preliminary evaluation of supersonic nozzles with square cross-section, as an alternative to conventional quiet-flow nozzles. After a brief summary of (1), a description of (2) is presented. Published work describing (3) is then summarized. The report concludes with a description of recent results for the Tollmien-Schlichting and Gortler instability in one of the square nozzles previously analyzed.

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

    NASA Technical Reports Server (NTRS)

    Bumba, V.

    1972-01-01

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

  3. Klimovskaya: A new geomagnetic observatory

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  4. Mantle superplumes induce geomagnetic superchrons

    NASA Astrophysics Data System (ADS)

    Olson, Peter; Amit, Hagay

    2015-07-01

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

  5. Climate determinism or Geomagnetic determinism?

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  6. Geomagnetic storms: association with incidence of depression as measured by hospital admission.

    PubMed

    Kay, R W

    1994-03-01

    The hypothesis that geomagnetic storms may partly account for the seasonal variation in the incidence of depression, by acting as a precipitant of depressive illness in susceptible individuals, is supported by a statistically significant 36.2% increase in male hospital admissions with a diagnosis of depressed phase, manic-depressive illness in the second week following such storms compared with geomagnetically quiet control periods. There is a smaller but not statistically significant increase in female psychotic depression and non-psychotic depression admissions following storms. There was no correlation between geomagnetic storm levels and number of male admissions with psychotic depression, which is consistent with a threshold event affecting predisposed individuals. Phase advance in pineal circadian rhythms of melatonin synthesis may be a possible mechanism of causation or be present as a consequence of 5-hydroxytryptamine and adrenergic system dysfunction associated with geomagnetic disturbance. Effects on cell membrane permeability, calcium channel activity and retinal magneto-receptors are suggested as possible underlying biochemical mechanisms. PMID:8199794

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

    USGS Publications Warehouse

    Campbell, W.H.

    1977-01-01

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

  8. Spatial and Temporal Variations of Solar Quiet Daily Sq Variation and Equatorial Electrojet Over Africa: Results From International Heliophysical Year

    NASA Astrophysics Data System (ADS)

    Rabiu, A.; Yumoto, K.; Bello, O.

    2010-12-01

    Space Environment Research Centre of Kyushu University, Japan, installed 13 units of Magnetic Data Acquisition Systems MAGDAS over Africa during the International Heliophysical Year IHY. Magnetic records from 10 stations along the African 96o Magnetic Meridian (Geographical 30o - 40o East) were examined for Solar quiet daily Sq variation in the three geomagnetic field components H, D and Z. Spatial variations of Sq in the geomagnetic components were examined. Signatures of equatorial electrojet and worldwide Sq were identified and studied in detail. H field experienced more variation within the equatorial electrojet zone. Diurnal and seasonal variations of the geomagnetic variations in the three components were discussed. Levels of inter-relationships between the Sq and its variability in the three components were statistically derived and interpreted in line with the mechanisms responsible for the variations of the geomagnetic field. Data from 2 magnetic observatories within equatorial electrojet EEJ strip and 2 stations outside the EEJ strip were employed to evaluate and study the signatures of the Equatorial electrojet over the African sector. The transient variations of the EEJ at two almost parallel axes using Lagos-Ilorin and Nairobi-Addis pairs were examined. The EEJ appear stronger in East than West Africa. The magnitudes and patterns of variation of EEJ strength along the two axes were examined for any simultaneity or otherwise of responses to ionospheric processes. The flow gradient of EEJ along the African sector was estimated and its diurnal variation studied.

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

    NASA Astrophysics Data System (ADS)

    Okpala, Kingsley

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  11. New insights on geomagnetic storms from observations and modeling

    SciTech Connect

    Jordanova, Vania K

    2009-01-01

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

  12. Extreme Geomagnetic Storms - 1868 - 2010

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  13. Fine structure of the 2003 geomagnetic jerk near China

    NASA Astrophysics Data System (ADS)

    Ou, J.; Du, A.

    2015-12-01

    The 2003 jerk has an abrupt change in the geomagnetic secular variation (SV), and was recognized as a local phenomenon of internal origin from the satellite observations (Olsen and Mandea, 2007). Notable strength of the 2003 jerk is located near China. The temporal and spatial features at this area are important to resolve the Earth's core fluid flow dynamics at local scale (e.g. Wardinski et al., 2008). We investigate the temporal-spatial development of the 2003 jerk in more detail near China with the ground-based observations and CHAOS-3 core field model. We select the data in the international geomagnetic quiet days to calculate the monthly means. In order to reduce the influence of the external field, we adopt a function comprising the terms associated with the indices of the geomagnetic activity, and the terms of the periodic signals on the observatory monthly means data (Stewart and Whaler, 1992). We then use an empirical AR-2 model to represent the internal field signals in the observatory data. The extreme detection is applied to identify the jerk in the SV time series. The onset time and the strength of the 2003 jerk are obtained through the detection for geomagnetic field component, X, Y and Z. The maximum of the strength of the 2003 jerk is located under the Indian mainland. The onset time of this jerk propagates approximately southeastward. Two jerks in 2001 and 2003 for the Z component are further compared and they are confirmed as independent processes. We suggest the jerk in 2001 identical to the well known 1999 jerk in Europe (Mandea et al., 2000). Our results reveal the fine structures of the 2003 jerk that corroborate the conclusions in previous studies. The larger scale time-spatial structure given by the AR-2 model constructed from ground observatory data (monthly values) is consistent with the results from the CHAOS-3 model. This structure can be applied for further inversion of the local core surface fluid flow motions.

  14. Worldwide Geomagnetic Data Collection and Management

    NASA Astrophysics Data System (ADS)

    Mandea, Mioara; Papitashvili, Vladimir

    2009-11-01

    Geomagnetic data provided by different platforms piece together a global picture of Earth's magnetic field and its interaction with geospace. Furthermore, a great diversity of the geomagnetic field changes, from secular (over decades to centuries) to short time variations (down to minutes and seconds), can be detected only through continued observations. An international effort to watch and record geomagnetic changes first began in the 1830s with a network of scientific observers organized by Karl Friedrich Gauss in Germany, and this effort has continued since then. One of the most remarkable achievements in understanding the geomagnetic field morphology and time behavior was made possible by the International Geophysical Year (IGY), an exploration and research effort that lasted for 18 months, starting on 1 July 1957. The IGY encompassed 11 geoscience disciplines, including geomagnetism. The IGY has represented a giant step forward in the quality and quantity of worldwide geomagnetic measurements, as well as in the widespread interest in magnetic measurements. A half century of probing the geomagnetic field spatial and temporal variations has produced a number of outstanding results, and the interested reader can find recent reviews on various geomagnetic field topics (from measurements to modeling) in Encyclopedia of Geomagnetism and Paleomagnetism [Gubbins and Herrero-Bervera, 2007] or Treatise on Geophysics: Geomagnetism [Kono, 2007].

  15. Magnetospheric convection during quiet or moderately disturbed times

    NASA Technical Reports Server (NTRS)

    Caudal, G.; Blanc, M.

    1988-01-01

    The processes which contribute to the large-scale plasma circulation in the earth's environment during quiet times, or during reasonable stable magnetic conditions are reviewed. The various sources of field-aligned current generation in the solar wind and the magnetosphere are presented. The generation of field-aligned currents on open field lines connected to either polar cap and the generation of closed field lines of the inner magnetosphere are examined. Consideration is given to the hypothesis of Caudal (1987) that loss processes of trapped particles are competing with adiabatic motions in the generation of field-aligned currents in the inner magnetosphere.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  17. Radio-quiet Fast Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Gopalswamy, N.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A.

    2004-12-01

    Coronal mass ejections (CMEs) drive shocks in the interplanetary medium that produce type II radio emission. These CMEs are faster and wider on the average, than the general population of CMEs. However, when we start from fast (speed > 900 km/s) and wide (angular width > 60 degrees), more than half of them are not associated with radio bursts. In order to understand why these CMEs are radio quiet, we collected all the fast and wide (FW) CMEs detected by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) and isolated those without associated type II radio bursts. The radio bursts were identified in the dynamic spectra of the Radio and Plasma Wave (WAVES) Experiment on board the Wind spacecraft. We also checked the list against metric type II radio bursts reported in Solar Geophysical Data and isolated those without any radio emission. This exercise resulted in about 140 radio-quiet FW CMEs. We identified the source regions of these CMEs using the Solar Geophysical Data listings, cross-checked against the eruption regions in the SOHO/EIT movies. We explored a number of possibilities for the radio-quietness: (i) Source region being too far behind the limb, (ii) flare size, (iii) brightness of the CME, and (iv) the density of the ambient medium. We suggest that a combination of CME energy and the Alfven speed profile of the ambient medium is primarily responsible for the radio-quietness of these FW CMEs.

  18. 76 FR 64353 - Buy Quiet Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... HUMAN SERVICES Centers for Disease Control and Prevention Buy Quiet Workshop AGENCY: National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC... Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention...

  19. 47 CFR 1.924 - Quiet zones.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... impact on the operations of radio astronomy or other facilities that are highly sensitive to interference. Consent throughout this paragraph means written consent from the quiet zone, radio astronomy, research... Radio Astronomy Observatory site located at Green Bank, Pocahontas County, West Virginia, and at...

  20. Reconnection brightenings in the quiet solar photosphere

    NASA Astrophysics Data System (ADS)

    Rouppe van der Voort, Luc H. M.; Rutten, Robert J.; Vissers, Gregal J. M.

    2016-08-01

    We describe a new quiet-Sun phenomenon which we call quiet-Sun Ellerman-like brightenings (QSEB). QSEBs are similar to Ellerman bombs (EB) in some respects but differ significantly in others. EBs are transient brightenings of the wings of the Balmer Hα line that mark strong-field photospheric reconnection in complex active regions. QSEBs are similar but smaller and less intense Balmer-wing brightenings that occur in quiet areas away from active regions. In the Hα wing, we measure typical lengths of less than 0.5 arcsec, widths of 0.23 arcsec, and lifetimes of less than a minute. We discovered them using high-quality Hα imaging spectrometry from the Swedish 1-m Solar Telescope (SST) and show that, in lesser-quality data, they cannot be distinguished from more ubiquitous facular brightenings, nor in the UV diagnostics currently available from space platforms. We add evidence from concurrent SST spectropolarimetry that QSEBs also mark photospheric reconnection events, but in quiet regions on the solar surface. The movies are available in electronic form at http://www.aanda.org

  1. Stiffness control of balance in quiet standing.

    PubMed

    Winter, D A; Patla, A E; Prince, F; Ishac, M; Gielo-Perczak, K

    1998-09-01

    Our goal was to provide some insights into how the CNS controls and maintains an upright standing posture, which is an integral part of activities of daily living. Although researchers have used simple performance measures of maintenance of this posture quite effectively in clinical decision making, the mechanisms and control principles involved have not been clear. We propose a relatively simple control scheme for regulation of upright posture that provides almost instantaneous corrective response and reduces the operating demands on the CNS. The analytic model is derived and experimentally validated. A stiffness model was developed for quiet standing. The model assumes that muscles act as springs to cause the center-of-pressure (COP) to move in phase with the center-of-mass (COM) as the body sways about some desired position. In the sagittal plane this stiffness control exists at the ankle plantarflexors, in the frontal plane by the hip abductors/adductors. On the basis of observations that the COP-COM error signal continuously oscillates, it is evident that the inverted pendulum model is severely underdamped, approaching the undamped condition. The spectrum of this error signal is seen to match that of a tuned mass, spring, damper system, and a curve fit of this "tuned circuit" yields omega n the undamped natural frequency of the system. The effective stiffness of the system, Ke, is then estimated from Ke = I omega n2, and the damping B is estimated from B = BW X I, where BW is the bandwidth of the tuned response (in rad/s), and I is the moment of inertia of the body about the ankle joint. Ten adult subjects were assessed while standing quietly at three stance widths: 50% hip-to-hip distance, 100 and 150%. Subjects stood for 2 min in each position with eyes open; the 100% stance width was repeated with eyes closed. In all trials and in both planes, the COP oscillated virtually in phase (within 6 ms) with COM, which was predicted by a simple 0th order spring

  2. Geomagnetic excursions and climate change

    NASA Technical Reports Server (NTRS)

    Rampino, M. R.

    1983-01-01

    Rampino argues that although Kent (1982) demonstrated that the intensity of natural remanent magnetism (NRM) in deep-sea sediments is sensitive to changes in sediment type, and hence is not an accurate indicator of the true strength of the geomagnetic field, it does not offer an alternative explanation for the proposed connections between excursions, climate, and orbital parameters. Kent replies by illustrating some of the problems associated with geomagnetic excursions by considering the record of proposed excursions in a single critical core. The large departure from an axial dipole field direction seen in a part of the sample is probably due to a distorted record; the drawing and storage of the sample, which is described, could easily have led to disturbance and distortion of the record.

  3. Teaching Geomagnetism in High School

    NASA Astrophysics Data System (ADS)

    Stern, D. P.

    2001-05-01

    Many high school curricula include a one-year course in Earth Sciences, often in the 9th grade (essentially pre-algebra). That is a good time to teach about geomagnetism. Not only are dipole reversals and sea-floor magnetization central to this subject, but this is a good opportunity to introduce students to magnetism and its connection to electric currents. The story of Oersted and Faraday give a fascinating insight into the uneven path of scientific discovery, the magnetic compass and William Gilbert provide a view of the beginnings of the scientific revolution, and even basic concepts of dynamo theory and its connection to solar physics can be included. A resource including all the suitable material now exists on the world-wide web at http://www-spof.gsfc.nasa.gov/earthmag/demagint.htm (home page). A 1-month unit on geomagnetism will be outlined.

  4. Ice ages and geomagnetic reversals

    NASA Technical Reports Server (NTRS)

    Wu, Patrick

    1992-01-01

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

  5. Heart attacks and geomagnetic activity.

    PubMed

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

    1979-10-18

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

  6. Global geomagnetic field mapping - from secular variation to geomagnetic excursions

    NASA Astrophysics Data System (ADS)

    Panovska, Sanja; Constable, Catherine

    2015-04-01

    The main source of the geomagnetic field is a self-sustaining dynamo produced by fluid motions in Earth's liquid outer core. We study the spatial and temporal changes in the internal magnetic field by mapping the time-varying geomagnetic field over the past 100 thousand years. This is accomplished using a new global data set of paleomagnetic records drawn from high accumulation rate sediments and from volcanic rocks spanning the past 100 thousand years (Late Pleistocene). Sediment data comprises 105 declination, 117 inclination and 150 relative paleointensity (RPI) records, mainly concentrated in northern mid-latitudes, although some are available in the southern hemisphere. Northern Atlantic and Western Pacific are regions with high concentrations of data. The number of available volcanic/archeomagnetic data is comparitively small on the global scale, especially in the Southern hemisphere. Temporal distributions show that the number of data increases toward more recent times with a good coverage for the past 50 ka. Laschamp excursion (41 ka BP) is well represented for both directional and intensity data. The significant increase in data compared to previous compilations results in an improvement over current geomagnetic field models covering these timescales. Robust aspects of individual sediment records are successfully captured by smoothing spline modeling allowing an estimate of random uncertainties present in the records. This reveals a wide range of fidelities across the sediment magnetic records. Median uncertainties are: 17° for declination (range, 1° to 113°), 6° for inclination (1° to 50°) and 0.4 for standardized relative paleointensity (0.02 to 1.4). The median temporal resolution of the records defined by the smoothing time is 400 years (range, 50 years to about 14 kyr). Using these data, a global, time-varying, geomagnetic field model is constructed covering the past 100 thousand years. The modeling directly uses relative forms of sediment

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

    SciTech Connect

    Cade, W.B.

    1993-06-01

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

  8. Do geomagnetic storms change the behaviour of the stingless bee guiruçu ( Schwarziana quadripunctata)?

    NASA Astrophysics Data System (ADS)

    Esquivel, Darci M. S.; Wajnberg, E.; Do Nascimento, F. S.; Pinho, M. B.; de Barros, H. G. P. Lins; Eizemberg, R.

    2007-02-01

    Six behavioural experiments were carried out to investigate the magnetic field effects on the nest-exiting flight directions of the honeybee Schwarziana quadripunctata ( Meliponini). No significant differences resulted during six experiment days under varying geomagnetic field and the applied static inhomogeneous field (about ten times the geomagnetic field) conditions. A surprising statistically significant response was obtained on a unique magnetic storm day. The magnetic nanoparticles in these bees, revealed by ferromagnetic resonance, could be involved in the observed effect of the geomagnetic storm.

  9. 49 CFR 222.42 - How does this rule affect Intermediate Quiet Zones and Intermediate Partial Quiet Zones?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.42 How does this rule affect Intermediate Quiet Zones...

  10. 49 CFR 222.42 - How does this rule affect Intermediate Quiet Zones and Intermediate Partial Quiet Zones?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.42 How does this rule affect Intermediate Quiet Zones...

  11. 49 CFR 222.42 - How does this rule affect Intermediate Quiet Zones and Intermediate Partial Quiet Zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.42 How does this rule affect Intermediate Quiet Zones...

  12. 49 CFR 222.42 - How does this rule affect Intermediate Quiet Zones and Intermediate Partial Quiet Zones?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.42 How does this rule affect Intermediate Quiet Zones...

  13. 49 CFR 222.42 - How does this rule affect Intermediate Quiet Zones and Intermediate Partial Quiet Zones?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.42 How does this rule affect Intermediate Quiet Zones...

  14. The Geomagnetic Field During a Reversal

    NASA Technical Reports Server (NTRS)

    Heirtzler, James R.

    2003-01-01

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

  15. On the day-to-day variation of the equatorial electrojet during quiet periods

    NASA Astrophysics Data System (ADS)

    Yamazaki, Y.; Richmond, A. D.; Maute, A.; Liu, H.-L.; Pedatella, N.; Sassi, F.

    2014-08-01

    It has been known for a long time that the equatorial electrojet varies from day to day even when solar and geomagnetic activities are very low. The quiet time day-to-day variation is considered to be due to irregular variability of the neutral wind, but little is known about how variable winds drive the electrojet variability. We employ a numerical model introduced by Liu et al. (2013), which takes into account weather changes in the lower atmosphere and thus can reproduce ionospheric variability due to forcing from below. The simulation is run for May and June 2009. Constant solar and magnetospheric energy inputs are used so that day-to-day changes will arise only from lower atmospheric forcing. The simulated electrojet current shows day-to-day variability of ±25%, which produces day-to-day variations in ground level geomagnetic perturbations near the magnetic equator. The current system associated with the day-to-day variation of the equatorial electrojet is traced based on a covariance analysis. The current pattern reveals return flow at both sides of the electrojet, in agreement with those inferred from ground-based magnetometer data in previous studies. The day-to-day variation in the electrojet current is compared with those in the neutral wind at various altitudes, latitudes, and longitudes. It is found that the electrojet variability is dominated by the zonal wind at 100-120 km altitudes near the magnetic equator. These results suggest that the response of the zonal polarization electric field to variable zonal winds is the main source of the day-to-day variation of the equatorial electrojet during quiet periods.

  16. The Causes of Geomagnetic Storms During Solar Maximum

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  17. Geomagnetic Field Reversals and Life on the Earth in Phanerozoic Time

    NASA Astrophysics Data System (ADS)

    Pechersky, D. M.

    2014-10-01

    Global paleomagnetic and biostratigraphic data are generalized. As a result it is found out that the direct connection between geomagnetic reversals, biozones and maxima of mass extinction of a biota is absent. At the same time it is noted close to a synchronous total picture of consistent changes of biozones and geomagnetic polarity. It is explained by the general source - the Earth's diurnal rotation. The reversal polarity of a geomagnetic field prevailed during the Phanerozoic that is agreed with the Earth's counterclockwise rotation. Change of polarity of a field, most likely, is connected with acceleration or deceleration of rotation speed of the internal core relative to the Earth's mantle. Lack of direct interrelation between changes in the biosphere and geomagnetic field indicate a lack of influence of a field on life evolution on Earth. It follows also from the fact that life on Earth developed from primitive unicellular forms to mammals and the man and diversity of biota was grew against a close condition of a geomagnetic field during ~2,5 billion years and irrespective of numerous geomagnetic reversals. Main conclusion: evolutionary development of life on Earth doesn't depend both on large changes of a geomagnetic field, and on the extreme catastrophic events conducting to mass extinction of a biota.

  18. Improvement of Quiet Standing Balance in Patients with Wallenberg Syndrome after Rehabilitation

    PubMed Central

    Na, Eun Hye; Han, Soo Jeong

    2011-01-01

    Objective To evaluate quiet standing balance of patients with Wallenberg syndrome before and after rehabilitation. Method Six patients with Wallenberg syndrome were enrolled within one month after being affected by an infarct of the lateral medulla. Quiet standing balance was assessed using posturography with eyes open and closed. The assessment was repeated after the patients had undergone rehabilitation treatment for three to nine months, and the results of the two assessments were compared. Results The quiet standing balance evaluation was performed by measurement of center of pressure (CoP) movement. In the initial test, the mean scores of mediolateral and anteroposterior speed, velocity movement, mediolateral and anteroposterior extent of CoP were all high, indicating impairments of quiet standing balance in the patients. After rehabilitation treatment, the anteroposterior speed and extent, the mediolateral speed and extent, and velocity moment of CoP showed statistically significant reductions in the eyes open condition (p<0.05), and the anteroposterior speed and extent and velocity moment of CoP had decreased in the eyes closed condition (p<0.05). Mediolateral speed and extent of CoP in the eyes closed condition had also decreased, but the reduction was not statistically significant. Conclusion This study demonstrated improvements of quiet standing balance, especially anteroposterior balance, in patients with Wallenberg syndrome following rehabilitation. We suggest that balance training is important in the rehabilitation of Wallenberg syndrome and that, as an objective measure of balance status, posturography is useful in the assessment of quiet standing balance. PMID:22506207

  19. Variability in the Mesosphere/Thermosphere/Ionosphere System During the Quiet Time of April 2002

    NASA Astrophysics Data System (ADS)

    Goncharenko, L. P.; Salah, J.; Coster, A.; Rideout, W.; Zhang, S. R.; Paxton, L.; Zhang, Y.; Crowley, G.; Taran, V.; Reinisch, B.; Clark, R.; Manson, A.; Mitchell, N.; Murayama, Y.; Riggin, D.; Singer, W.

    2003-12-01

    We investigate the structure of the global mesosphere-thermosphere-ionosphere system using multi-instrument observations during the April 2002 period, with focus on geomagnetically quiet periods. Large variations in electron density were observed at midlatitudes by the array of incoherent scatter radars, ionosondes and GPS receivers. On April 16, 2002, electron density decreases to ~50-70% of the level observed on Apr 15, 2002. This depletion far exceeds commonly observed 10-20% quiet-time variations. At the same time, the observations from the array of MF and meteor radars show global presence of planetary wave disturbances, and a westward offset in the zonal wind of 15 m/s was noticed at locations coincident with the area of large variations in the electron density. We find that variations in ionospheric parameters have a strong relationship with neutral density, and show that an extensive area of depleted electron density as observed by GPS receivers, ISR radars and ionosondes is coincident with the area of large decrease in the column integrated O/N2 ratio measured by the GUVI instrument on board of TIMED satellite. Similar variations are also predicted by the TIMEGCM/ASPEN model in both O/N2 ratio and electron density, though the magnitude of the variations in the model is significantly smaller.

  20. The influence of quiet eye training and pressure on attention and visuo-motor control.

    PubMed

    Vine, Samuel J; Wilson, Mark R

    2011-03-01

    The aim of this study was to examine the efficacy of an intervention designed to train effective visual attentional control (quiet eye-training) for a far aiming skill, and determine whether such training protected against attentional disruptions associated with performing under pressure. Sixteen novice participants wore a mobile eye-tracker to assess their visual attentional control (quiet eye) during the completion of 520 basketball free throws carried out over 8 days. They first performed 40 pre-test free throws and were randomly allocated into a quiet eye (QE) training or Control group (technical instruction only). Participants then performed 360 free throws during a training period and a further 120 test free throws under conditions designed to manipulate the level of anxiety experienced. The QE trained group maintained more effective visual attentional control and performed significantly better in the pressure test compared to the Control group, providing support for the efficacy of attentional training for visuo-motor skills.

  1. The Hidden Gifts of Quiet Kids

    ERIC Educational Resources Information Center

    Trierweiler, Hannah

    2006-01-01

    The author relates that she was an introvert child. It has always taken her time and energy to find her place in a group. As a grown-up, she still needed quiet time to regroup during a busy day. In this article, the author presents an interview with Marti Olsen Laney, author of "The Hidden Gifts of the Introverted Child." During the interview,…

  2. Tectonic evolution of the Perth Abyssal Plain's Quiet Zone, Southeast Indian Ocean

    NASA Astrophysics Data System (ADS)

    Ehrlich, Zohar Louis; Granot, Roi; Williams, Simon E.

    2013-04-01

    During the Late Jurassic period, the Greater-Indian plate was torn away from Australia, dissociating East Gondwanaland. The Perth Abyssal Plain (PAP) is the southernmost rift segment along the western Australian margin, and has an onset age of ~136 Ma. New marine magnetic and swath bathymetry data, crossing the entire PAP, were acquired recently on geophysical cruise ss2011v06 aboard the R/V Southern Surveyor. These have lead to the outline of conjugate Indian and Australian M-series isochrons in the east and west PAP, respectively [1]. Yet, most of the PAP was created during the Cretaceous Normal Superchron (CNS, 121-83 Ma), a period of no geomagnetic field reversals, hence no comprehensive tectonic model for the PAP exists . Here we present preliminary findings of an analytic bathymetric and magnetic investigation aimed at elucidating the PAP's quiet zone. Recent discoveries regarding the evolution of the geomagnetic field during the CNS [2] provide new time markers that can be utilized to date the oceanic crust. The magnetic anomaly data exhibit the Q2 anomaly marker (~108 Ma), further constraining the spreading history of the PAP. Together with the ridgelet transform method [3] for automated abyssal hill delineation, we present new constraints on the development of crustal construction processes (spreading location, direction and rates) that took place along the PAP spreading center. References: [1] S.E. Williams, J.M. Whittaker, R. Granot, R.D. Muller (in preparation), New constraints on the seafloor spreading history in the Perth Abyssal Plain. [2] Granot, R., J. Dyment, and Y. Gallet (2012), Geomagnetic field variability during the Cretaceous Normal Superchron, Nature Geoscience, 5(3), 220-223. [3] Downey, N. J. and R. W. Clayton (2007), A ridgelet transform method for constraining tectonic models via abyssal-hill morphology, Geochemistry Geophysics Geosystems, 8, Q03004, doi: 10.1029/2006GC001440.

  3. The heating of the quiet solar chromosphere

    NASA Technical Reports Server (NTRS)

    Kalkofen, Wolfgang

    1990-01-01

    The quiet solar chromosphere shows three distinct regions. Ordered according to the strength of the emission from the low and middle chromosphere they are (1) the magnetic elements on the boundary of supergranulation cells, (2) the bright points in the cell interior, and (3) the truly quiet chromosphere, also in the cell interior. The magnetic elements on the cell boundary are associated with intense magnetic fields and are heated by waves with very long periods, ranging from six to twelve minutes; the bright points are associated with magnetic elements of low field strength and are heated by (long-period) waves with periods near the acoustic cutoff period of three minutes; and the quiet cell interior, which is free of magnetic field, may be heated by short-period acoustic waves, with periods below one minute. This paper reviews mainly the heating of the bright points and concludes that the large-amplitude, long-period waves heating the bright points dissipate enough energy to account for their chromospheric temperature structure.

  4. Nanoflare Heating of the Quiet Sun

    NASA Astrophysics Data System (ADS)

    Viall, N. M.; Klimchuk, J. A.

    2015-12-01

    How the solar corona is heated to temperatures of over 1 MK, while the photosphere below is only ~ 6000 K remains one of the outstanding problems in all of space science. Solving this problem is crucial for understanding Sun-Earth connections, and will provide new insight into universal processes such as magnetic reconnection and wave-particle interactions. We use a systematic technique to analyze the properties of coronal heating throughout the solar corona using data taken with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Our technique computes cooling times of the coronal plasma on a pixel-by-pixel basis and has the advantage that it analyzes all of the coronal emission, including the diffuse emission surrounding distinguishable coronal features. We have already applied this technique to 15 different active regions, and find clear evidence for dynamic heating and cooling cycles that are consistent with the 'impulsive nanoflare' scenario. What about the rest of the Solar corona? Whether the quiet Sun is heated in a similar or distinct manner from active regions is a matter of great debate. Here we apply our coronal heating analysis technique to quiet Sun locations. We find areas of quiet Sun locations that also undergo dynamic heating and cooling cycles, consistent with impulsive nanoflares. However, there are important characteristics that are distinct from those of active regions.

  5. Radio-quiet Gamma-ray Pulsars

    NASA Astrophysics Data System (ADS)

    Lin, Lupin Chun-Che

    2016-09-01

    A radio-quiet γ-ray pulsar is a neutron star that has significant γ-ray pulsation but without observed radio emission or only limited emission detected by high sensitivity radio surveys. The launch of the Fermi spacecraft in 2008 opened a new epoch to study the population of these pulsars. In the 2nd Fermi Large Area Telescope catalog of γ-ray pulsars, there are 35 (30 % of the 117 pulsars in the catalog) known samples classified as radio-quiet γ-ray pulsars with radio flux density (S1400) of less than 30 μJy. Accompanying the observations obtained in various wavelengths, astronomers not only have the opportunity to study the emitting nature of radio-quiet γ-ray pulsars but also have proposed different models to explain their radiation mechanism. This article will review the history of the discovery, the emission properties, and the previous efforts to study pulsars in this population. Some particular cases known as Geminga-like pulsars (e.g., PSR J0633+1746, PSR J0007+7303, PSR J2021+4026, and so on) are also specified to discuss their common and specific features.

  6. BUY QUIET INITIATIVE IN THE USA

    PubMed Central

    Beamer, Bryan; McCleery, Trudi; Hayden, Charles

    2016-01-01

    Noise-induced hearing loss is still considered one of the most common work-related illnesses in the United States of America. The U.S. National Institute for Occupational Safety and Health launched a national Buy Quiet campaign to raise awareness of the importance of purchasing quieter equipment. Buy Quiet encourages companies to seek out and demand quieter equipment thus driving the market to design and create quieter products. In the long run, investment in noise controls should be more prevalent as the market demands quieter products. This paradigm occurs as the market for quieter products expands both from the supply side (manufacturers) and the demand side (tool and equipment purchasers). The key to experiencing the reduced costs and increased benefits of Buy Quiet will be to develop partnerships between manufacturers and consumers. To this end, the U.S. National Institute for Occupational Safety and Health continues to work with partners to educate stakeholders about the risks and true costs of noise-induced hearing loss, as well as the economic benefits of buying quieter equipment. PMID:27274613

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  8. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W.; Taylor, E.R. Jr.; Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems` responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  9. Electric Utility Industry Experience with Geomagnetic Disturbances

    SciTech Connect

    Barnes, P.R.

    1991-01-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as a few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration.

  10. Electric utility industry experience with geomagnetic disturbances

    SciTech Connect

    Barnes, P.R.; Rizy, D.T.; McConnell, B.W. ); Taylor, E.R. Jr. ); Tesche, F.M.

    1991-09-01

    A geomagnetic disturbance (GMD) by its nature occurs globally and almost simultaneously. Severe geomagnetic storms cause problems for electric power systems. The vulnerability of electric power systems to such events has apparently increased during the last 10 to 20 years because power system transmission lines have become more interconnected and have increased in length and because power systems are now operated closer to their limits than in the past. In this report, the experience of electric utilities during geomagnetic storms is examined and analyzed. Measured data, effects on power system components, and power system impacts are considered. It has been found that electric power systems are susceptible to geomagnetically induced earth-surface potential gradients as small as few (2 to 3) volts per kilometer, corresponding to a storm of K-6 intensity over an area of high earth resistivity. The causes and effects are reasonably well understood, but additional research is needed to develop a better understanding of solar-induced geomagnetic storms and the responses of power systems to these types of storms. A better understanding of geomagnetic storms and the power systems' responses to GMDs is needed so that mitigation measures can be implemented that will make power systems less susceptible to severe geomagnetic disturbances. A GMD caused by a large high-altitude nuclear detonation is similar in many ways to that of solar-induced geomagnetic storms except that a nuclear-caused disturbance would be much more intense with a far shorter duration. 49 refs.

  11. Quiet Eye Duration Is Responsive to Variability of Practice and to the Axis of Target Changes

    ERIC Educational Resources Information Center

    Horn, Robert R.; Okumura, Michelle S.; Alexander, Melissa G. F.; Gardin, Fredrick A.; Sylvester, Curtis T.

    2012-01-01

    We tested the hypothesis that quiet eye, the final fixation before the initiation of a movement in aiming tasks, is used to scale the movement's parameters. Two groups of 12 participants (N = 24) threw darts to targets in the horizontal and vertical axes under conditions of higher (random) or lower (blocked) target variability. Supporting our…

  12. Effect of geomagnetic storms upon blood sedimentation dynamics in ischemic heart disease patients

    NASA Astrophysics Data System (ADS)

    Gurfinkel, Youri I.; Voeikov, Vladimir L.; Kondakov, Sergey E.; Demidion, P. Y.; Dmitriev, Andey Y.; Ozerskii, S. Y.

    2000-11-01

    The sedimentation properties of blood of 13 ischemic heart disease patients and 2 healthy volunteers have been analyzed using a special computerized optical device for high temporal resolution tracing of red blood/plasma boundary movement rate (ESR-graphy). The kinetic curves of red blood sedimentation are substantially nonmonotonic and exhibit multiple accelerations, decelerations and even backwards movement of the red blood/plasma boundary. The intensity of blood sedimentation rate oscillations is significantly higher in the blood of patients and voluteers on days of enhanced geomagnetic activity than on quiet days. In healthy donors, blood oscillations were also observed on active geomagnetic days, however, their intensity was lower, the sedimentation rate started to oscillate after a longer time upon pipette installation, and the oscillation frequency was lower than in the patients' blood. Thus, blood is highly responsive to changes in geomagnetic field activity. Possibly oscillatory behavior mechanism of blood sedimentation rate and the diagnostic and prognostic merits of the ESR graphs are discussed.

  13. Retention of quiet eye in older skilled basketball players.

    PubMed

    Fischer, Lennart; Rienhoff, Rebecca; Tirp, Judith; Baker, Joseph; Strauss, Bernd; Schorer, Jörg

    2015-01-01

    There is mounting research to suggest that cognitive and motor expertise is more resistant to age-related decline than more general capacities. The authors investigated the retention of skills in medium-aged skilled (n = 14) and older-aged skilled (n = 7) athletes by comparing them with medium-aged less skilled (n = 15) and older-aged less skilled (n = 15) participants. Participants performed basketball free throws and dart throws as a transfer task under standardized conditions. Motor performance (accuracy) and perceptual performance (quiet eye) were examined across the four groups. There were significant differences between skill groups and age groups in throwing accuracy on both throwing tasks. Skilled players outperformed less skilled and medium-aged players outperformed older-aged players in basketball and dart throws. There were no significant differences in quiet eye duration across the skill or age groups in either task. These results indicate expertise in a perceptual motor task such as the basketball free throw can be retained in older athletes and that present models of skill maintenance should be re-evaluated to consider the issue of transfer.

  14. Geomagnetic Disturbances Caused by Internal Atmospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Sonneman, G.

    1984-01-01

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

  15. Geophysical excitation of nutation and geomagnetic jerks

    NASA Astrophysics Data System (ADS)

    Vondrák, Jan; Ron, Cyril

    2014-05-01

    Recently Zinovy Malkin (2013) proposed that the observed changes of Free Core Nutation parameters (phase, amplitude) might be related to geomagnetic jerks (rapid changes of the secular variations of geomagnetic field). We tested this hypothesis and found that if the numerical integration of Brzezinski broad-band Liouville equations of atmospheric/oceanic excitations is re-initialized at the epochs of geomagnetic jerks, the agreement between the integrated and observed celestial pole offsets is improved significantly. This approach however tacitly assumes that the influence of geomagnetic jerks has a stepwise character, which is physically not acceptable. The present study continues in this effort by introducing a simple continuous excitation function (hypothetically due to geomagnetic jerks). The results of numerical integration of atmospheric/oceanic excitations plus this newly introduced excitation are then compared with the observed celestial pole offsets.

  16. History of the geomagnetic field

    USGS Publications Warehouse

    Doell, Richard R.

    1969-01-01

    Direct measurements of the direction and strength of the earth's magnetic field have provided a knowledge of the field's form and behavior during the last few hundreds of years. For older times, however, it has been necessary to measure the magnetism of certain rocks to learn what the geomagnetic field was like. For example, when a lava flow solidifies (at temperatures near 1000??C) and cools through the Curie point of the magnetic minerals contained in it (around 500??C) it acquires a remanent magnetism that is (1) very weak, (2) very stablel, (3) paralle to the direction of the ambient geomagnetic field, and (4) proportional in intensity to the ambient field. Separating, by various analytical means, this magnetization from other 'unwanted' magnetizations has allowed paleomagnetists to study the historical and prehistorical behavior of the earth's field. It has been learned, for example, that the strength of the field was almost twice its present value 2000 years ago and that it has often completely reversed its polarity. Paleo-magnetists have also confirmed that most oceans are, geologically speaking, relatively new features, and that the continents have markedly changed their positions over the surface of the earth. ?? 1969 The American Institute of Physics.

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

    NASA Astrophysics Data System (ADS)

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

    1989-02-01

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

  18. Anomalous phenomena on HF radio paths during geomagnetic disturbances

    NASA Astrophysics Data System (ADS)

    Blagoveshchenskii, D. V.

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Sharma, A. K.; et al.

    2006-11-01

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

  20. Improved geomagnetic referencing in the Arctic environment

    USGS Publications Warehouse

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

    2016-01-01

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

  1. Design of Quiet Rotorcraft Approach Trajectories

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Burley, Casey L.; Boyd, D. Douglas, Jr.; Marcolini, Michael A.

    2009-01-01

    A optimization procedure for identifying quiet rotorcraft approach trajectories is proposed and demonstrated. The procedure employs a multi-objective genetic algorithm in order to reduce noise and create approach paths that will be acceptable to pilots and passengers. The concept is demonstrated by application to two different helicopters. The optimized paths are compared with one another and to a standard 6-deg approach path. The two demonstration cases validate the optimization procedure but highlight the need for improved noise prediction techniques and for additional rotorcraft acoustic data sets.

  2. Jovian electrons during solar quiet time periods

    NASA Astrophysics Data System (ADS)

    del Peral, L.; Gómez-Herrero, R.; Rodríguez-Frías, M. D.; Sequeiros, J.; Kunow, H.; Müller-Mellin, R.

    2002-03-01

    The electron spectrum in the energy range 150 keV to 10 MeV, measured by EPHIN sensor onboard SOHO observatory during 1996 quiet time periods, is presented. The results show that the dominant electron population is of jovian origin. The spectral indexes obtained range from 1.5 to 1.8. In this work an estimation of the emission intensity of electrons from the jovian magnetosphere is also obtained. Unexpected recurrence of jovian electrons at the middle of 1996 during poor Earth-Jupiter magnetic connection have been observed.

  3. Delayed stochastic differential model for quiet standing

    NASA Astrophysics Data System (ADS)

    Yao, W.; Yu, P.; Essex, C.

    2001-02-01

    A physiological quiet standing model, described by a delayed differential equation, subject to a white noise perturbation, is proposed to study the postural control system of human beings. It has been found that the white noise destabilizes the equilibrium state, and inertia accelerates the destabilizing process, and that the position of a person is detected and processed by the person's nervous system with a delay. This paper focuses on the analysis of Hopf bifurcation and its stability in this context. Based on the analytical predictions confirmed by numerical simulations, it has been shown that the posture of a person is controlled in such a way that possible amplitude oscillations are minimized.

  4. The quiet revolution of numerical weather prediction.

    PubMed

    Bauer, Peter; Thorpe, Alan; Brunet, Gilbert

    2015-09-01

    Advances in numerical weather prediction represent a quiet revolution because they have resulted from a steady accumulation of scientific knowledge and technological advances over many years that, with only a few exceptions, have not been associated with the aura of fundamental physics breakthroughs. Nonetheless, the impact of numerical weather prediction is among the greatest of any area of physical science. As a computational problem, global weather prediction is comparable to the simulation of the human brain and of the evolution of the early Universe, and it is performed every day at major operational centres across the world.

  5. Brief quiet ego contemplation reduces oxidative stress and mind-wandering.

    PubMed

    Wayment, Heidi A; Collier, Ann F; Birkett, Melissa; Traustadóttir, Tinna; Till, Robert E

    2015-01-01

    Excessive self-concern increases perceptions of threat and defensiveness. In contrast, fostering a more inclusive and expanded sense of self can reduce stress and improve well-being. We developed and tested a novel brief intervention designed to strengthen a student's compassionate self-identity, an identity that values balance and growth by reminding them of four quiet ego characteristics: detached awareness, inclusive identity, perspective taking, and growth. Students (N = 32) in their first semester of college who reported greater self-protective (e.g., defensive) goals in the first 2 weeks of the semester were invited to participate in the study. Volunteers were randomly assigned to one of three conditions: quiet ego contemplation (QEC), QEC with virtual reality (VR) headset (QEC-VR), and control. Participants came to the lab three times to engage in a 15-min exercise in a 30-days period. The 15-min QEC briefly described each quiet ego characteristic followed by a few minutes time to reflect on what that characteristic meant to them. Those in the QEC condition reported improved quiet ego characteristics and pluralistic thinking, decreases in a urinary marker of oxidative stress, and reduced mind-wandering on a cognitive task. Contrary to expectation, participants who wore the VR headsets while listening to the QEC demonstrated the least improvement. Results suggest that a brief intervention that reduces self-focus and strengthens a more compassionate self-view may offer an additional resource that individuals can use in their everyday lives. PMID:26483734

  6. Brief quiet ego contemplation reduces oxidative stress and mind-wandering.

    PubMed

    Wayment, Heidi A; Collier, Ann F; Birkett, Melissa; Traustadóttir, Tinna; Till, Robert E

    2015-01-01

    Excessive self-concern increases perceptions of threat and defensiveness. In contrast, fostering a more inclusive and expanded sense of self can reduce stress and improve well-being. We developed and tested a novel brief intervention designed to strengthen a student's compassionate self-identity, an identity that values balance and growth by reminding them of four quiet ego characteristics: detached awareness, inclusive identity, perspective taking, and growth. Students (N = 32) in their first semester of college who reported greater self-protective (e.g., defensive) goals in the first 2 weeks of the semester were invited to participate in the study. Volunteers were randomly assigned to one of three conditions: quiet ego contemplation (QEC), QEC with virtual reality (VR) headset (QEC-VR), and control. Participants came to the lab three times to engage in a 15-min exercise in a 30-days period. The 15-min QEC briefly described each quiet ego characteristic followed by a few minutes time to reflect on what that characteristic meant to them. Those in the QEC condition reported improved quiet ego characteristics and pluralistic thinking, decreases in a urinary marker of oxidative stress, and reduced mind-wandering on a cognitive task. Contrary to expectation, participants who wore the VR headsets while listening to the QEC demonstrated the least improvement. Results suggest that a brief intervention that reduces self-focus and strengthens a more compassionate self-view may offer an additional resource that individuals can use in their everyday lives.

  7. Brief quiet ego contemplation reduces oxidative stress and mind-wandering

    PubMed Central

    Wayment, Heidi A.; Collier, Ann F.; Birkett, Melissa; Traustadóttir, Tinna; Till, Robert E.

    2015-01-01

    Excessive self-concern increases perceptions of threat and defensiveness. In contrast, fostering a more inclusive and expanded sense of self can reduce stress and improve well-being. We developed and tested a novel brief intervention designed to strengthen a student’s compassionate self-identity, an identity that values balance and growth by reminding them of four quiet ego characteristics: detached awareness, inclusive identity, perspective taking, and growth. Students (N = 32) in their first semester of college who reported greater self-protective (e.g., defensive) goals in the first 2 weeks of the semester were invited to participate in the study. Volunteers were randomly assigned to one of three conditions: quiet ego contemplation (QEC), QEC with virtual reality (VR) headset (QEC-VR), and control. Participants came to the lab three times to engage in a 15-min exercise in a 30-days period. The 15-min QEC briefly described each quiet ego characteristic followed by a few minutes time to reflect on what that characteristic meant to them. Those in the QEC condition reported improved quiet ego characteristics and pluralistic thinking, decreases in a urinary marker of oxidative stress, and reduced mind-wandering on a cognitive task. Contrary to expectation, participants who wore the VR headsets while listening to the QEC demonstrated the least improvement. Results suggest that a brief intervention that reduces self-focus and strengthens a more compassionate self-view may offer an additional resource that individuals can use in their everyday lives. PMID:26483734

  8. Geomagnetic activity: Dependence on solar wind parameters

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1977-01-01

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

  9. Multiscale Features of Large Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    De Michelis, P.; Consolini, G.

    2011-12-01

    The present study is focused on the analysis of the multiscale features of four large geomagnetic storms that occurred from 2000 to 2003. In particular, we analyse the fluctuations of these extreme events as recorded along the horizontal component of the geomagnetic field in seven different canadian geomagnetic observatories, by decomposing the signal via the Hilbert-Huang transform (HHT). This empirical method, that is alternative to traditional data-analysis methods, consists in an empirical mode decomposition (EMD) and in the Hilbert spectral analysis, and it is designed specifically for analyzing nonlinear and nonstationary data. The features of the intrinsic mode functions (IMFs) are studied as a function of the magnetic latitude.

  10. On the watch for geomagnetic storms

    USGS Publications Warehouse

    Green, Arthur W.; Brown, William M.

    1997-01-01

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

  11. Comparison of GPS-TEC variation during quiet and disturbed period using the Holt-Winter method and IRI-2012 model over Malaysia

    NASA Astrophysics Data System (ADS)

    Ahmed Ismail, Nouf Abd Emunim; Abdullah, Mardina; Hasbi, Alina Marie

    2016-07-01

    Total Electron Content (TEC) is the main parameter in the ionosphere that has significant effects on radio wave; it changes the speed and direction of the signal propagation, causing the delay of the Global Positioning System (GPS) signals. Therefore, it is crucial to validate the performance of the ionospheric model to reveal the variety of ionospheric behaviour during quiet and disturbed period. This research presents the performance evaluation of the statistical Holt-Winter method and IRI-2012 model using three topside electron density options: IRI-2001, IRI01-corr and NeQuick with the observed GPS-TEC during quiet and disturbed period. The GPS-TEC data were derived from the dual frequency GPS receiver at JUPEM (Department of Survey and Mapping Malaysia), from the UUMK station (north Peninsular Malaysia) at geographic coordinates of 6.46°N-100.50°E and geomagnetic coordinates of 3.32°S-172.99°E and TGPG station (south Peninsular Malaysia) at geographic coordinates of 1.36°N-104.10°E and geomagnetic coordinates of 8.43°S -176.53°E, during March of 2013. The maximum value of the GPS-TEC was at the post noon time at 17:00 LT and the minimum was in the early morning from 6:00-7:00 LT. During the quiet period, the maximum GPS-TEC at the UUMK station was 52 TECU while at the TGPG station, it was 60 TECU. During the disturbed period, when intense geomagnetic storm occurred on 17 March 2013, the maximum GPS-TEC recorded was 58 TECU and 65 TECU in UUMK and TGPG station, respectively. The diurnal hourly variation during the quiet period indicated that IRI-2001, IRI01-corr, and NeQuick had overestimation agreement during the day hours except for the time between 11:00-19:00 LT when IRI01-corr and NeQuick showed underestimation, while during 13:00-20:00 LT, IRI-2001 showed slight underestimation whereas the Holt-Winter method showed good agreement with GPS-TEC. During the disturbed period, IRI-2001 showed overestimation agreement for all hours, while the IRI01-corr

  12. A new regard about Surlari National Geomagnetic Observatory

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  14. Minimax confidence intervals in geomagnetism

    NASA Technical Reports Server (NTRS)

    Stark, Philip B.

    1992-01-01

    The present paper uses theory of Donoho (1989) to find lower bounds on the lengths of optimally short fixed-length confidence intervals (minimax confidence intervals) for Gauss coefficients of the field of degree 1-12 using the heat flow constraint. The bounds on optimal minimax intervals are about 40 percent shorter than Backus' intervals: no procedure for producing fixed-length confidence intervals, linear or nonlinear, can give intervals shorter than about 60 percent the length of Backus' in this problem. While both methods rigorously account for the fact that core field models are infinite-dimensional, the application of the techniques to the geomagnetic problem involves approximations and counterfactual assumptions about the data errors, and so these results are likely to be extremely optimistic estimates of the actual uncertainty in Gauss coefficients.

  15. Frequency of Proterozoic geomagnetic superchrons

    NASA Astrophysics Data System (ADS)

    Driscoll, Peter E.; Evans, David A. D.

    2016-03-01

    Long-term geodynamo evolution is expected to respond to inner core growth and changing patterns of mantle convection. Three geomagnetic superchrons, during which Earth's magnetic field maintained a near-constant polarity state through tens of Myr, are known from the bio/magnetostratigraphic record of Phanerozoic time, perhaps timed according to supercontinental episodicity. Some geodynamo simulations incorporating a much smaller inner core, as would have characterized Proterozoic time, produce field reversals at a much lower rate. Here we compile polarity ratios of site means within a quality-filtered global Proterozoic paleomagnetic database, according to recent plate kinematic models. Various smoothing parameters, optimized to successfully identify the known Phanerozoic superchrons, indicate 3-10 possible Proterozoic superchrons during the 1300 Myr interval studied. Proterozoic geodynamo evolution thus appears to indicate a relatively narrow range of reversal behavior through the last two billion years, implying either remarkable stability of core dynamics over this time or insensitivity of reversal rate to core evolution.

  16. Ionosphere over Africa: Results from Geomagnetic Field Measurements During International Heliophysical Year IHY

    NASA Astrophysics Data System (ADS)

    Rabiu, A. B.; Yumoto, K.; Falayi, E. O.; Bello, O. R.; Magdas/Cpmn Group

    2011-12-01

    Space Environment Research Centre of Kyushu University, Japan, installed 13 units of Magnetic Data Acquisition Systems MAGDAS over Africa during the International Heliophysical Year IHY. Magnetic records from 10 stations along the African 96o Magnetic Meridian (Geographical 30° - 40° East) were examined for Solar quiet daily Sq variations in the two geomagnetic field components H and D. Latitudinal variations of Sq in the geomagnetic components were examined. Signatures of equatorial electrojet and worldwide Sq were identified and studied in detail. H field experienced more variation within the equatorial electrojet zone. Diurnal variations of the geomagnetic variations in the two components were discussed. Sq H is expectedly consistently maximum within the electrojet zone as a result of EEJ. Sq D has maximum values at about -20ɛ (sunrise), -10ɛ (noon time) and +10ɛ (sunset). Levels of inter-relationships between the Sq and its variability in the two components were statistically derived and interpreted in line with the mechanisms responsible for the variations of the geomagnetic field. Data from 2 magnetic observatories within equatorial electrojet EEJ strip and 2 stations outside the EEJ strip were employed to evaluate and study the signatures of the Equatorial electrojet over the African sector. The transient variations of the EEJ at two almost parallel axes using Lagos-Ilorin (West Africa) and Nairobi-Addis Ababa (East Africa) pairs were examined. The eastern electrojet appeared stronger than the western. The latitudinal and longitudinal profiles of the Sq were examined and inferences drawn from observed results were discussed.

  17. Deciphering records of geomagnetic reversals

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Fournier, Alexandre

    2016-06-01

    Polarity reversals of the geomagnetic field are a major feature of the Earth's dynamo. Questions remain regarding the dynamical processes that give rise to reversals and the properties of the geomagnetic field during a polarity transition. A large number of paleomagnetic reversal records have been acquired during the past 50 years in order to better constrain the structure and geometry of the transitional field. In addition, over the past two decades, numerical dynamo simulations have also provided insights into the reversal mechanism. Yet despite the large paleomagnetic database, controversial interpretations of records of the transitional field persist; they result from two characteristics inherent to all reversals, both of which are detrimental to an ambiguous analysis. On the one hand, the reversal process is rapid and requires adequate temporal resolution. On the other hand, weak field intensities during a reversal can affect the fidelity of magnetic recording in sedimentary records. This paper is aimed at reviewing critically the main reversal features derived from paleomagnetic records and at analyzing some of these features in light of numerical simulations. We discuss in detail the fidelity of the signal extracted from paleomagnetic records and pay special attention to their resolution with respect to the timing and mechanisms involved in the magnetization process. Records from marine sediments dominate the database. They give rise to transitional field models that often lead to overinterpret the data. Consequently, we attempt to separate robust results (and their subsequent interpretations) from those that do not stand on a strong observational footing. Finally, we discuss new avenues that should favor progress to better characterize and understand transitional field behavior.

  18. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones... that is added onto an existing quiet zone, provided there is no public highway-rail grade crossing at... crossing, unless a New Quiet Zone or New Partial Quiet Zone is being added onto an existing quiet zone....

  19. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones... that is added onto an existing quiet zone, provided there is no public highway-rail grade crossing at... crossing, unless a New Quiet Zone or New Partial Quiet Zone is being added onto an existing quiet zone....

  20. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones... that is added onto an existing quiet zone, provided there is no public highway-rail grade crossing at... crossing, unless a New Quiet Zone or New Partial Quiet Zone is being added onto an existing quiet zone....

  1. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones... that is added onto an existing quiet zone, provided there is no public highway-rail grade crossing at... crossing, unless a New Quiet Zone or New Partial Quiet Zone is being added onto an existing quiet zone....

  2. 49 CFR 222.35 - What are the minimum requirements for quiet zones?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones... that is added onto an existing quiet zone, provided there is no public highway-rail grade crossing at... crossing, unless a New Quiet Zone or New Partial Quiet Zone is being added onto an existing quiet zone....

  3. Airesearch QCGAT program. [quiet clean general aviation turbofan engines

    NASA Technical Reports Server (NTRS)

    Heldenbrand, R. W.; Norgren, W. M.

    1979-01-01

    A model TFE731-1 engine was used as a baseline for the NASA quiet clean general aviation turbofan engine and engine/nacelle program designed to demonstrate the applicability of large turbofan engine technology to small general aviation turbofan engines, and to obtain significant reductions in noise and pollutant emissions while reducing or maintaining fuel consumption levels. All new technology design for rotating parts and all items in the engine and nacelle that contributed to the acoustic and pollution characteristics of the engine system were of flight design, weight, and construction. The major noise, emissions, and performance goals were met. Noise levels estimated for the three FAR Part 36 conditions, are 10 t0 15 ENPdB below FAA requirements; emission values are considerably reduced below that of current technology engines; and the engine performance represents a TSFC improvement of approximately 9 percent over other turbofan engines.

  4. No quiet surrender: molecular guardians in multiple sclerosis brain.

    PubMed

    Steinman, Lawrence

    2015-04-01

    The brain under immunological attack does not surrender quietly. Investigation of brain lesions in multiple sclerosis (MS) reveals a coordinated molecular response involving various proteins and small molecules ranging from heat shock proteins to small lipids, neurotransmitters, and even gases, which provide protection and foster repair. Reduction of inflammation serves as a necessary prerequisite for effective recovery and regeneration. Remarkably, many lesion-resident molecules activate pathways leading to both suppression of inflammation and promotion of repair mechanisms. These guardian molecules and their corresponding physiologic pathways could potentially be exploited to silence inflammation and repair the injured and degenerating brain and spinal cord in both relapsing-remitting and progressive forms of MS and may be beneficial in other neurologic and psychiatric conditions.

  5. No quiet surrender: molecular guardians in multiple sclerosis brain

    PubMed Central

    Steinman, Lawrence

    2015-01-01

    The brain under immunological attack does not surrender quietly. Investigation of brain lesions in multiple sclerosis (MS) reveals a coordinated molecular response involving various proteins and small molecules ranging from heat shock proteins to small lipids, neurotransmitters, and even gases, which provide protection and foster repair. Reduction of inflammation serves as a necessary prerequisite for effective recovery and regeneration. Remarkably, many lesion-resident molecules activate pathways leading to both suppression of inflammation and promotion of repair mechanisms. These guardian molecules and their corresponding physiologic pathways could potentially be exploited to silence inflammation and repair the injured and degenerating brain and spinal cord in both relapsing-remitting and progressive forms of MS and may be beneficial in other neurologic and psychiatric conditions. PMID:25831441

  6. Transverse pelvic rotation during quiet human stance.

    PubMed

    Günther, Michael; Otto, Daniel; Müller, Otto; Blickhan, Reinhard

    2008-04-01

    The mechanism of two-legged quiet stance is unclear. This study specifically investigated biomechanical parameters characterising the mechanisms of rotation around the longitudinal axis (parallel to gravitational acceleration, i.e. in the transverse plane parallel to the ground). Subjects (10) were examined while standing quietly on two force platforms which measured the transverse component of the ground reaction torque (GRT). In addition, right and left hip kinematics were acquired by tracking markers in the sagittal plane. The pelvic rotation in the transverse plane (pelvic angle) was then calculated from the anterior-posterior coordinates of the hip markers. We verified the hypothesis that the pelvis generally may be coupled to the ground by a rotational stiffness provided by both legs. Thus, we asked whether the transverse GRT component may be proportional to the pelvic angle. This hypothesis was rejected. However, the transverse GRT component could be identified as one rotational stabilising mechanism which drove the higher-frequency (>1 Hz) deflections of the pelvic angle back to its lower-frequency fraction. The respective stiffness coefficient between transverse GRT component and relative displacement between higher- and lower-frequency pelvic angular fraction was about 2.4 Nm/degrees. Implications for the character and the localisation of active control of body rotation around the longitudinal axis are discussed.

  7. Microwave properties of a quiet sea

    NASA Technical Reports Server (NTRS)

    Stacey, J.

    1985-01-01

    The microwave flux responses of a quiet sea are observed at five microwave frequencies and with both horizontal and vertical polarizations at each frequency--a simultaneous 10 channel receiving system. The measurements are taken from Earth orbit with an articulating antenna. The 10 channel responses are taken simultaneously since they share a common articulating collector with a multifrequency feed. The plotted flux responses show: (1) the effects of the relative, on-axis-gain of the collecting aperture for each frequency; (2) the effects of polarization rotation in the output responses of the receive when the collecting aperture mechanically rotates about a feed that is fixed; (3) the difference between the flux magnitudes for the horizontal and vertical channels, at each of the five frequencies, and for each pointing position, over a 44 degree scan angle; and (4) the RMS value of the clutter--as reckoned over the interval of a full swath for each of the 10 channels. The clutter is derived from the standard error of estimate of the plotted swath response for each channel. The expected value of the background temperature is computed for each of the three quiet seas. The background temperature includes contributions from the cosmic background, the downwelling path, the sea surface, and the upwelling path.

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

    NASA Astrophysics Data System (ADS)

    Sahai, Y.; Fagundes, P. R.; Becker-Guedes, F.; Abalde, J. R.; Crowley, G.; Pi, X.; Igarashi, K.; Amarante, G. M.; Pimenta, A. A.; Bittencourt, J. A.

    2003-04-01

    A new ionospheric sounding station using a Canadian Advanced Digital Ionosonde (CADI) was established for routine measurements by the " Universidade do Vale do Paraiba (UNIVAP) " at São Jos&{acute;e} dos Campos (23.2oS, 45.9oW; dip latitude 17.6oS), Brazil, in August 2000. Response of the coupled magnetosphere-ionosphere-thermosphere system during major geomagnetic storms is one of the key issues related to space weather studies. A major geomagnetic storm with gradual commencement at about 0100 UT was observed on 31 March 2001. The storm on 31 March had two main phases, the first with Kp=9- between 0300-0900 UT and | Dst |max =358 nT at 0900 UT and second with Kp=8+ between 1800-2100 UT and | Dst |max =285 nT. In this paper, we present and discuss salient features from the ionospheric sounding measurements carried out at S. J. Campos on the three consecutive UT days 30 March (quiet), 31 March (disturbed) and 01 April (recovery) 2001. During most of the storm period, the foF2 values showed negative phase, whereas during both the main phases large F-region height variations were observed. In order to study the longitudinal differences observed in the F-region during the storm, the simultaneous ionospheric sounding measurements carried out at S. J. Campos, El Arenosillo (37.1oN, 6.7o W; dip latitude 31.2oN), Spain, Okinawa (26.3oN, 127.8oE; dip latitude 21.2oN), Japan and Wakkanai (45.5oN, 141.7oE; dip latitude 41.2oN), Japan, during the period 30 March - 01 April 2001, have been analyzed. In addition, global ionospheric TEC maps from the worldwide network of GPS receivers are presented showing widespread TEC changes during both the main and recovery phases of the storm. The ionospheric sounding measurements are compared with the ASPEN-TIMEGCM model runs appropriate for the storm conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  10. [ON HUMAN BODY REACTION TO A CHANGED GEOMAGNETIC BACKGROUND].

    PubMed

    Sterlikova, I V

    2015-01-01

    Purpose of the work was to test the concept about existence of a heliobiological relation in the Earth's middle-latitude region for which to analyze, as an example, frequency of circulatory disease exacerbation, mental and behavior disorders, and respiratory diseases (bronchial asthma). The subject and object of the experimental statistic survey have been dwellers of city of Murom (Vladimir region) located in middle-latitude geomagnetic region Φ ≈ 53 degrees. The source material in the investigation was medical data of the Murom ambulance service and geophysical data of the Borok geomagnetic observatory (Yaroslavl region). The survey went on 3 years from February, 1985 till December, 1987 and coincided with the rise of the 11th solar cycle. The largest number of calls to the ambulance service due to acute circulatory condition, mental or behavior disorders, respiratory diseases (bronchial asthma particularly) and their fatal outcome fell on periods of long absence of high-frequency geomagnetic pulsation within the frequency range of human biorhythms.

  11. [ON HUMAN BODY REACTION TO A CHANGED GEOMAGNETIC BACKGROUND].

    PubMed

    Sterlikova, I V

    2015-01-01

    Purpose of the work was to test the concept about existence of a heliobiological relation in the Earth's middle-latitude region for which to analyze, as an example, frequency of circulatory disease exacerbation, mental and behavior disorders, and respiratory diseases (bronchial asthma). The subject and object of the experimental statistic survey have been dwellers of city of Murom (Vladimir region) located in middle-latitude geomagnetic region Φ ≈ 53 degrees. The source material in the investigation was medical data of the Murom ambulance service and geophysical data of the Borok geomagnetic observatory (Yaroslavl region). The survey went on 3 years from February, 1985 till December, 1987 and coincided with the rise of the 11th solar cycle. The largest number of calls to the ambulance service due to acute circulatory condition, mental or behavior disorders, respiratory diseases (bronchial asthma particularly) and their fatal outcome fell on periods of long absence of high-frequency geomagnetic pulsation within the frequency range of human biorhythms. PMID:26554135

  12. Geomagnetic Observatory Data for Real-Time Applications

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. Total electron content behavior over Japan during geomagnetic storms

    NASA Astrophysics Data System (ADS)

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

    2005-01-01

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

  14. Solar-Terrestrial Relations and Geomagnetic Variations

    NASA Astrophysics Data System (ADS)

    Ogunade, S. O.

    1995-01-01

    An overview of the solar environment and terrestrial magnetism is presented. The interactions of the solar environment and terrestrial magnetism are then discussed as they result in the creation of the magnetosphere and ionosphere with their corresponding current systems. Geomagnetic variations resulting from these current systems are discussed with regards to the observations made on the Earth's surface. Some useful and disruptive effects of the geomagnetic variations on navigation, shortwave radio communication, space satellite orbits and other technological systems are discussed.

  15. The International Geomagnetic Reference Field, 2005

    USGS Publications Warehouse

    Rukstales, Kenneth S.; Love, Jeffrey J.

    2007-01-01

    This is a set of five world charts showing the declination, inclination, horizontal intensity, vertical component, and total intensity of the Earth's magnetic field at mean sea level at the beginning of 2005. The charts are based on the International Geomagnetic Reference Field (IGRF) main model for 2005 and secular change model for 2005-2010. The IGRF is referenced to the World Geodetic System 1984 ellipsoid. Additional information about the USGS geomagnetism program is available at: http://geomag.usgs.gov/

  16. How the geomagnetic field vector reverses polarity

    USGS Publications Warehouse

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

    1985-01-01

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

  17. Geomagnetic main field modeling using magnetohydrodynamic constraints

    NASA Technical Reports Server (NTRS)

    Estes, R. H.

    1985-01-01

    The influence of physical constraints are investigated which may be approximately satisfied by the Earth's liquid core on models of the geomagnetic main field and its secular variation. A previous report describes the methodology used to incorporate nonlinear equations of constraint into the main field model. The application of that methodology to the GSFC 12/83 field model to test the frozen-flux hypothesis and the usefulness of incorporating magnetohydrodynamic constraints for obtaining improved geomagnetic field models is described.

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

    PubMed

    Persinger, M A

    2002-06-01

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

  19. Geomagnetic disturbance effects on power systems

    SciTech Connect

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

    1993-07-01

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

  20. The "Quiet" Troubles of Low-Income Children

    ERIC Educational Resources Information Center

    Weissbourd, Richard

    2009-01-01

    Most of the troubles poor at-risk children have are not "loud" problems like disruptive behavior or gang involvement. They are "quiet." The range of these problems is vast. Hunger, dehydration, asthma, obesity, and hearing problems can all insidiously trip children up in school. Some quiet problems are psychological--depression, anxiety, the fear…

  1. Mired in the Shadows: Quiet Students in Secondary Schools

    ERIC Educational Resources Information Center

    Thompson, Greg; Bell, James

    2011-01-01

    Quiet students are a feature of the organisation of secondary schools. Using qualitative methods and Deleuzean conceptualisations of modern subjectivity, this paper explores the ways that quiet students negotiate the terrain of their school. These negotiations often seem to produce a self that is trapped rather than a subject who seizes…

  2. Geomagnetically trapped energetic helium nuclei

    SciTech Connect

    Chen, J.; Gregory Guzik, T.; Wefel, J.P.; Roger Pyle, K.; Cooper, J.F.

    1996-07-01

    Geomagnetically trapped helium nuclei, at high energy ({approximately}40{endash}100 MeV/nucleon), have been measured by the ONR-604 instrument during the 1990/1991 CRRES mission. The ONR-604 instrument resolved the isotopes of helium with a mass resolution of 0.1 amu. The energetic helium observed at {ital L}{lt}2.3 have a pitch angle distribution peaking perpendicular to the local magnetic field, which is characteristic of a trapped population. Both the trapped {sup 3}He and {sup 4}He show two peaks at {ital L}=1.2 and 1.9. Each isotope{close_quote}s flux, in each peak, can be characterized by a power law energy spectrum. The energy spectrum of the {sup 3}He is different from that of {sup 4}He, indicating that the {sup 3}He/{sup 4}He ratio is energy dependent. Over the energy range of 51{endash}86 MeV/nucleon, the {sup 3}He/{sup 4}He ratio is 8.7{plus_minus}3.1 at {ital L}=1.1{endash}1.5 and is 2.4{plus_minus}0.6 at {ital L}=1.5{endash}2.3. The trapped helium counting rates decrease gradually with time during the CRRES mission, when the anomalous component is excluded from the inner heliosphere, indicating that these high energy ions were not injected by flares during this time period. The decrease in intensity is attributed mainly to the events around {ital L}=1.9. The helium around {ital L}=1.2, dominated by {sup 3}He, does not show a significant temporal evolution, which implies a long-term energetic trapped {sup 3}He population. Two possible origins of the geomagnetically trapped helium isotopes are the interactions of energetic protons with the upper atmosphere and/or the inward diffusion and acceleration of helium ions due to electric-field fluctuations. {copyright} {ital 1996 American Institute of Physics.}

  3. Quiet(er) marine protected areas.

    PubMed

    Williams, Rob; Erbe, Christine; Ashe, Erin; Clark, Christopher W

    2015-11-15

    A core task in endangered species conservation is identifying important habitats and managing human activities to mitigate threats. Many marine organisms, from invertebrates to fish to marine mammals, use acoustic cues to find food, avoid predators, choose mates, and navigate. Ocean noise can affect animal behavior and disrupt trophic linkages. Substantial potential exists for area-based management to reduce exposure of animals to chronic ocean noise. Incorporating noise into spatial planning (e.g., critical habitat designation or marine protected areas) may improve ecological integrity and promote ecological resilience to withstand additional stressors. Previous work identified areas with high ship noise requiring mitigation. This study introduces the concept of "opportunity sites" - important habitats that experience low ship noise. Working with existing patterns in ocean noise and animal distribution will facilitate conservation gains while minimizing societal costs, by identifying opportunities to protect important wildlife habitats that happen to be quiet.

  4. The quiet short-haul research aircraft

    NASA Technical Reports Server (NTRS)

    Cochrane, J. A.

    1983-01-01

    The design concepts, performance capabilities, and projected applications of the Quiet Short-Haul Research Aircraft (QSRA) are discussed. The propulsive lift system of the QSRA provides the lift required for short field operations at low community noise levels. This system consists of four high bipass ratio, geared turbofan engines mounted so that the engine exhaust flows across the upper surface of the wing (upper surface blowing). Large specially shaped flaps behind each engine control the direction of the flow for each phase of flight. A 95 passenger short haul transport based on this technology could operate out of a 2500 foot runway with a combined takeoff and landing 90 EPNdB footprint area of 2.7 sq mi.

  5. Quiet swimming at low Reynolds number

    NASA Astrophysics Data System (ADS)

    Andersen, Anders; Wadhwa, Navish; Kiorboe, Thomas

    2015-11-01

    Planktonic organisms that inhabit the water masses of the oceans are faced with a dilemma: They need to swim to find food and mates, but by swimming they inevitably create flow disturbances that attract predators. We discuss that planktonic swimmers can reduce the flow disturbances due to their swimming, simply by appropriately arranging their propulsion apparatus. Motivated by recent experiments, we demonstrate that a three-Stokeslet model of a breast stroke swimmer is an example of a quiet swimmer. We show that the flow disturbances around the organism in both the near field and the far field are small in comparison with simple pullers and pushers, and we find that the far field power laws are valid surprisingly close to the organism. Breast stroke swimming may thus be advantageous, and this might explain why it is very common in the world of the plankton.

  6. Geomagnetic substorm association of plasmoids

    SciTech Connect

    Moldwin, M.B.; Hughes, W.J. )

    1993-01-01

    The relationship of geomagnetic substorms and plasmoids is examined by determining the correlation of the 366 plasmoids identified by Moldwin and Hughes (1992) with ground auroral zone magnetograms and geosynchronous particle data signatures of substorm onsets. Over 84% of the plasmoid events occurred between 5 and 60 min after a substorm onset. We also find near one-to-one correlation between large isolated substorm signatures in the near-Earth region and signatures consistent with a passing plasmoid in the distant tail (i.e., a traveling compression region, or an actual plasmoid observation). However, there does not appear to be an absolute correspondence of every substorm onset to a plasmoid signature in the deep tail especially, for periods of prolonged disturbance that have multiple substorm insets. A correlation of inter-planetary magnetic field B. south with plasmoid observations was also found. The locations of the near- and far-Earth reconnection sites are estimated using the time of flight of the plasmoids from substorm onset to their observation at ISEE 3. The estimates of the near- and far-Earth reconnection sites are highly variable and range from 10 to 140 RE, 32 refs., 4 figs. 2 tabs.

  7. On Geomagnetism and Paleomagnetism I

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    2000-01-01

    A partial description of Earth's broad scale, core-source magnetic field has been developed and tested three ways. The description features an expected, or mean, spatial magnetic power spectrum that is approximately inversely proportional to horizontal wavenumber atop Earth's core. This multipole spectrum describes a magnetic energy range; it is not steep enough for Gubbins' magnetic dissipation range. Temporal variations of core multipole powers about mean values are to be expected and are described statistically, via trial probability distribution functions, instead of deterministically, via trial solution of closed transport equations. The distributions considered here are closed and neither require nor prohibit magnetic isotropy. The description is therefore applicable to, and tested against, both dipole and low degree non-dipole fields. In Part 1, a physical basis for an expectation spectrum is developed and checked. The description is then combined with main field models of twentieth century satellite and surface geomagnetic field measurements to make testable predictions of the radius of Earth's core. The predicted core radius is 0.7% above the 3480 km seismological value. Partial descriptions of other planetary dipole fields are noted.

  8. Geomagnetic Field Modeling with DMSP

    NASA Astrophysics Data System (ADS)

    Alken, P.; Redmon, R. J.; Rich, F. J.; Maus, S.; Luhr, H.

    2013-12-01

    The Defense Meteorological Satellite Program (DMSP) launches and maintains a network of satellites to monitor the meteorological, oceanographic, and solar-terrestrial physics environments. In the past decade, geomagnetic field modelers have focused much attention on magnetic measurements from missions such as CHAMP, Oersted and SAC-C. With the completion of the CHAMP mission in 2010, there have been limited satellite-based vector and scalar magnetic field measurements available for main field modeling. In this study, we investigate the feasibility of using the Special Sensor Magnetometer (SSM) instrument onboard DMSP for main field modeling. These vector field measurements are calibrated to compute instrument timing shifts, scale factors, offsets, and non-orthogonalities in the fluxgate magnetometer cores. Euler angles are then computed to determine the orientation of the vector magnetometer with respect to a local coordinate system. We fit a degree 12 main field model to the dataset and compare with similar models such as the World Magnetic Model (WMM) and IGRF. Initial results indicate that the DMSP dataset will be a valuable source for main field modeling for the years between CHAMP and the upcoming Swarm mission.

  9. Impact of the lower atmosphere on the ionosphere response to a geomagnetic superstorm

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.

    2016-09-01

    Numerical simulations in the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM) are performed to elucidate the impacts of lower atmosphere forcing on the ionosphere response to a geomagnetic superstorm. In particular, how the ionosphere variability due to the October 2003 Halloween storm would be different if it occurred in January coincident with a major sudden stratosphere warming (SSW) event is investigated. The TIE-GCM simulations reveal that the E× B vertical drift velocity and total electron content (TEC) respond differently to the geomagnetic forcing when the lower atmosphere forcing is representative of SSW conditions compared to climatological lower atmosphere forcing conditions. Notably, the storm time variations in the E× B vertical drift velocity differ when the SSW-induced zonal mean and tidal variability in the lower thermosphere are considered, and this is in part due to effects of the SSW on the equatorial ionosphere being potentially misinterpreted as being of geomagnetic origin. Differences in the TEC response to the geomagnetic storm can be up to 100% (˜30 TEC unit (TECU: 1 TECU = 1016 el m-2)) of the storm-induced TEC change, and the temporal variability of the TEC during the storm recovery phase is considerably different if SSW effects are considered. The results demonstrate that even during periods of extreme geomagnetic forcing, it is important to consider the effects of lower atmosphere forcing on the ionosphere variability.

  10. Probing geomagnetic storm-driven magnetosphere-ionosphere dynamics in D-region ionosphere using VLF signal propagation characteristics

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    When propagating in the Earth-ionosphere waveguide, the amplitude and phase of VLF/LF radio signals are sensitive to changes in the electrical conductivity of the lower ionosphere. This characteristic makes it useful in studying sudden ionospheric disturbances, especially those related to prompt X-ray flux output from solar flares and gamma ray bursts (GRBs). However, strong geomagnetic disturbances and/or storm conditions are known to produce large and global ionospheric disturbances, which can significantly affect VLF radio propagation in the D region ionosphere. Diurnal VLF signature may also convey other important information, especially those related to geomagnetic disturbance/storm induced ionospheric changes. In this paper, using the data of three propagation paths (at latitudes 40-54º), we analyze in detail the trend of anomalies of VLF diurnal signal under varying solar and geomagnetic space environmental conditions to identify possible geomagnetic footprints on the D region ionosphere.

  11. The influence of ankle muscle activation on postural sway during quiet stance.

    PubMed

    Warnica, Meagan J; Weaver, Tyler B; Prentice, Stephen D; Laing, Andrew C

    2014-04-01

    Although balance during quiet standing is postulated to be influenced by multiple factors, including ankle stiffness, it is unclear how different mechanisms underlying increases in stiffness affect balance control. Accordingly, this study examined the influence of muscle activation and passive ankle stiffness increases on the magnitude and frequency of postural sway. Sixteen young adults participated in six quiet stance conditions including: relaxed standing, four muscle active conditions (10%, 20%, 30% and 40% maximum voluntary contraction (MVC)), and one passive condition wearing an ankle foot orthotic (AFO). Kinetics were collected from a force plate, while whole-body kinematics were collected with a 12-sensor motion capture system. Bilateral electromyographic signals were recorded from the tibialis anterior and medial gastrocnemius muscles. Quiet stance sway amplitude (range and root mean square) and frequency (mean frequency and velocity) in the sagittal plane were calculated from time-varying centre of gravity (COG) and centre of pressure (COP) data. Compared to the relaxed standing condition, metrics of sway amplitude were significantly increased (between 37.5 and 63.2%) at muscle activation levels of 30% and 40% MVC. Similarly, frequency measures increased between 30.5 and 154.2% in the 20-40% MVC conditions. In contrast, passive ankle stiffness, induced through the AFO, significantly decreased sway amplitude (by 23-26%), decreased COG velocity by 13.8%, and increased mean COP frequency by 24.9%. These results demonstrate that active co-contraction of ankle musculature (common in Parkinson's Disease patients) may have differential effects on quiet stance balance control compared to the use of an ankle foot orthotic (common for those recovering from stroke).

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  13. Bats Use Geomagnetic Field: Behavior and Mechanism

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Tian, L.; Zhang, B.; Zhu, R.

    2015-12-01

    It has been known that numerous animals can use the Earth's magnetic field for spatial orientation and long-distance navigation, nevertheless, how animals can respond to the magnetic field remain mostly ambiguous. The intensities of the global geomagnetic field varies between 23 and 66 μT, and the geomagnetic field intensity could drop to 10% during geomagnetic polarity reversals or geomagnetic excursions. Such dramatic changes of the geomagnetic field may pose a significant challenge for the evolution of magnetic compass in animals. For examples, it is vital whether the magnetic compass can still work in such very weak magnetic fields. Our previous experiment has demonstrated that a migratory bat (Nyctalus plancyi) uses a polarity compass for orientation during roosting when exposed to an artificial magnetic field (100 μT). Recently, we experimentally tested whether the N. plancyi can sense very weak magnetic fields that were even lower than those of the present-day geomagnetic field. Results showed: 1) the bats can sense the magnetic north in a field strength of present-day local geomagnetic field (51μT); 2) As the field intensity decreased to only 1/5th of the natural intensity (10 μT), the bats still responded by positioning themselves at the magnetic north. Notably, as the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT). Hence, N. plancyi is able to detect the direction of a magnetic field with intensity range from twice to 1/5th of the present-day field strength. This allows them to orient themselves across the entire range of present-day global geomagnetic field strengths and sense very weak magnetic fields. We propose that this high sensitivity might have evolved in bats as the geomagnetic field strength varied and the polarity reversed tens of times over the past fifty million years since the origin of bats. The physiological mechanisms underlying

  14. Principles of major geomagnetic storms forecasting

    NASA Astrophysics Data System (ADS)

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

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

  15. The causes of recurrent geomagnetic storms

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  16. Quiet Clean Short-haul Experimental Engine (QCSEE) clean combustor test report

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A component pressure test was conducted on a F101 PFRT combustor to evaluate the emissions levels of this combustor design at selected under the wing and over the wing operating conditions for the quiet clean short haul experimental engine (QCSEE). Emissions reduction techniques were evaluated which included compressor discharge bleed and sector burning in the combustor. The results of this test were utilized to compare the expected QCSEE emissions levels with the emission goals of the QCSEE engine program.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  18. Magnetospheric mapping with quantitative geomagnetic field models

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    The Mead-Fairfield geomagnetic field models were used to trace field lines between the outer magnetosphere and the earth's surface. The results are presented in terms of ground latitude and local time contours projected to the equatorial plane and into the geomagnetic tail. With these contours various observations can be mapped along field lines between high and low altitudes. Low altitudes observations of the polar cap boundary, the polar cusp, the energetic electron trapping boundary and the sunward convection region are projected to the equatorial plane and compared with the results of the model and with each other. The results provide quantitative support to the earlier suggestions that the trapping boundary is associated with the last closed field line in the sunward hemisphere, the polar cusp is associated with the region of the last closed field line, and the polar cap projects to the geomagnetic tail and has a low latitude boundary corresponding to the last closed field line.

  19. Scaling laws from geomagnetic time series

    USGS Publications Warehouse

    Voros, Z.; Kovacs, P.; Juhasz, A.; Kormendi, A.; Green, A.W.

    1998-01-01

    The notion of extended self-similarity (ESS) is applied here for the X - component time series of geomagnetic field fluctuations. Plotting nth order structure functions against the fourth order structure function we show that low-frequency geomagnetic fluctuations up to the order n = 10 follow the same scaling laws as MHD fluctuations in solar wind, however, for higher frequencies (f > l/5[h]) a clear departure from the expected universality is observed for n > 6. ESS does not allow to make an unambiguous statement about the non triviality of scaling laws in "geomagnetic" turbulence. However, we suggest to use higher order moments as promising diagnostic tools for mapping the contributions of various remote magnetospheric sources to local observatory data. Copyright 1998 by the American Geophysical Union.

  20. International Geomagnetic Reference Field: the third generation.

    USGS Publications Warehouse

    Peddie, N.W.

    1982-01-01

    In August 1981 the International Association of Geomagnetism and Aeronomy revised the International Geomagnetic Reference Field (IGRF). It is the second revision since the inception of the IGRF in 1968. The revision extends the earlier series of IGRF models from 1980 to 1985, introduces a new series of definitive models for 1965-1976, and defines a provisional reference field for 1975- 1980. The revision consists of: 1) a model of the main geomagnetic field at 1980.0, not continuous with the earlier series of IGRF models together with a forecast model of the secular variation of the main field during 1980-1985; 2) definitive models of the main field at 1965.0, 1970.0, and 1975.0, with linear interpolation of the model coefficients specified for intervening dates; and 3) a provisional reference field for 1975-1980, defined as the linear interpolation of the 1975 and 1980 main-field models.-from Author

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

    NASA Technical Reports Server (NTRS)

    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.

  2. POGO satellite orbit corrections: an opportunity to improve the quality of the geomagnetic field measurements?

    NASA Astrophysics Data System (ADS)

    Stockmann, Reto; Christiansen, Freddy; Olsen, Nils; Jackson, Andrew

    2015-06-01

    We present an attempt to improve the quality of the geomagnetic field measurements from the Polar Orbiting Geophysical Observatory (POGO) satellite missions in the late 1960s. Inaccurate satellite positions are believed to be a major source of errors for using the magnetic observations for field modelling. To improve the data, we use an iterative approach consisting of two main parts: one is a main field modelling process to obtain the radial field gradient to perturb the orbits and the other is the state-of-the-art GPS orbit modelling software BERNESE to calculate new physical orbits. We report results based on a single-day approach showing a clear increase of the data quality. That single-day approach leads, however, to undesirable orbital jumps at midnight. Furthermore, we report results obtained for a much larger data set comprising almost all of the data from the three missions. With this approach, we eliminate the orbit discontinuities at midnight but only tiny quality improvements could be achieved for geomagnetically quiet data. We believe that improvements to the data are probably still possible, but it would require the original tracking observations to be found.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  5. Large Geomagnetic Storms: Introduction to Special Section

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2010-01-01

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

  6. Satellite data for geomagnetic field modeling

    NASA Astrophysics Data System (ADS)

    Langel, R. A.; Baldwin, R. T.

    1992-06-01

    Satellite measurements of the geomagnetic fields began with the launch of Sputnik 3 in May of 1958 and have continued sporadically. Spacecraft making significant contributions to main field geomagnetism will be reviewed and the characteristics of their data discussed, including coverage, accuracy, resolution and data availability. Of particular interest are Vanguard 3; Cosmos 49, Ogo's -2, -4, and -6; Magsat; DE-2; and POGS. Spacecraft make measurements on a moving platfrom above the ionosphere as opposed to measurements from fixed observatories and surveys, both below the ionosphere. Possible future missions, such as Aristoteles and GOS are reviewed.

  7. Satellite Data for Geomagnetic Field Modeling

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Baldwin, R. T.

    1992-01-01

    Satellite measurements of the geomagnetic fields began with the launch of Sputnik 3 in May of 1958 and have continued sporadically. Spacecraft making significant contributions to main field geomagnetism will be reviewed and the characteristics of their data discussed, including coverage, accuracy, resolution and data availability. Of particular interest are Vanguard 3; Cosmos 49, Ogo's -2, -4, and -6; Magsat; DE-2; and POGS. Spacecraft make measurements on a moving platfrom above the ionosphere as opposed to measurements from fixed observatories and surveys, both below the ionosphere. Possible future missions, such as Aristoteles and GOS are reviewed.

  8. Anencephalus, drinking water, geomagnetism and cosmic radiation.

    PubMed

    Archer, V E

    1979-01-01

    The mortality rates from anencephalus from 1950-1969 in Canadian cities are shown to be strongly correlated with city growth rate and with horizontal geomagnetic flux, which is directly related to the intensity of cosmic radiation. They are also shown to have some association with the magnesium content of drinking water. Prior work with these data which showed associations with magnesium in drinking water, mean income, latitude and longitude was found to be inadequate because it dismissed the observed geographic associations as having little biological meaning, and because the important variables of geomagnetism and city growth rate were overlooked. PMID:433919

  9. MAGNETIC LOOPS IN THE QUIET SUN

    SciTech Connect

    Wiegelmann, T.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Borrero, J. M.; Schmidt, W.; Pillet, V. MartInez; Bonet, J. A.; Domingo, V.; Knoelker, M.; Title, A. M.

    2010-11-10

    We investigate the fine structure of magnetic fields in the atmosphere of the quiet Sun. We use photospheric magnetic field measurements from SUNRISE/IMaX with unprecedented spatial resolution to extrapolate the photospheric magnetic field into higher layers of the solar atmosphere with the help of potential and force-free extrapolation techniques. We find that most magnetic loops that reach into the chromosphere or higher have one footpoint in relatively strong magnetic field regions in the photosphere. Ninety-one percent of the magnetic energy in the mid-chromosphere (at a height of 1 Mm) is in field lines, whose stronger footpoint has a strength of more than 300 G, i.e., above the equipartition field strength with convection. The loops reaching into the chromosphere and corona are also found to be asymmetric in the sense that the weaker footpoint has a strength B < 300 G and is located in the internetwork (IN). Such loops are expected to be strongly dynamic and have short lifetimes, as dictated by the properties of the IN fields.

  10. MAGNETIC BRIGHT POINTS IN THE QUIET SUN

    SciTech Connect

    Sanchez Almeida, J.; Bonet, J. A.; Viticchie, B.

    2010-05-20

    We present a visual determination of the number of bright points (BPs) existing in the quiet Sun, which are structures though to trace intense kG magnetic concentrations. The measurement is based on a 0.''1 angular resolution G-band movie obtained with the Swedish Solar Telescope at the solar disk center. We find 0.97 BPs Mm{sup -2}, which is a factor 3 larger than any previous estimate. It corresponds to 1.2 BPs per solar granule. Depending on the details of the segmentation, the BPs cover between 0.9% and 2.2% of the solar surface. Assuming their field strength to be 1.5 kG, the detected BPs contribute to the solar magnetic flux with an unsigned flux density between 13 G and 33 G. If network and inter-network regions are counted separately, they contain 2.2 BPs Mm{sup -2} and 0.85 BPs Mm{sup -2}, respectively.

  11. Quiet swimming at low Reynolds number.

    PubMed

    Andersen, Anders; Wadhwa, Navish; Kiørboe, Thomas

    2015-04-01

    The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode that eliminates the stresslet component of the flow and leads to a faster spatial decay of the fluid disturbance described by a force quadrupole that decays as one over distance cubed. Motivated by recent experimental results on fluid disturbances due to small aquatic organisms, we demonstrate that a three-Stokeslet model of a swimming organism which uses breast stroke type kinematics is an example of such a quiet swimmer. We show that the fluid disturbance in both the near field and the far field is significantly reduced by appropriately arranging the propulsion apparatus, and we find that the far field power laws are valid surprisingly close to the organism. Finally, we discuss point force models as a general framework for hypothesis generation and experimental exploration of fluid mediated predator-prey interactions in the planktonic world.

  12. Quiet swimming at low Reynolds number

    NASA Astrophysics Data System (ADS)

    Andersen, Anders; Wadhwa, Navish; Kiørboe, Thomas

    2015-04-01

    The stresslet provides a simple model of the flow created by a small, freely swimming and neutrally buoyant aquatic organism and shows that the far field fluid disturbance created by such an organism in general decays as one over distance squared. Here we discuss a quieter swimming mode that eliminates the stresslet component of the flow and leads to a faster spatial decay of the fluid disturbance described by a force quadrupole that decays as one over distance cubed. Motivated by recent experimental results on fluid disturbances due to small aquatic organisms, we demonstrate that a three-Stokeslet model of a swimming organism which uses breast stroke type kinematics is an example of such a quiet swimmer. We show that the fluid disturbance in both the near field and the far field is significantly reduced by appropriately arranging the propulsion apparatus, and we find that the far field power laws are valid surprisingly close to the organism. Finally, we discuss point force models as a general framework for hypothesis generation and experimental exploration of fluid mediated predator-prey interactions in the planktonic world.

  13. Quiet-time Solar Wind Superhalo Electrons

    NASA Astrophysics Data System (ADS)

    Wang, L.; Yang, L.; Tu, C. Y.; He, J.; Wimmer-Schweingruber, R. F.; Li, G.; Salem, C. S.; Bale, S. D.

    2015-12-01

    Superhalo electrons carry important information on the electron acceleration in the solar wind. Using the STEREO/STE electron measurements at ~2-20 keV and WIND/3DP measurements at ~20-200 keV, we find that solar wind superhalo electrons are present in the interplanetary medium (IPM) even in absence of any significant solar and interplanetary activity. The observed superhalo electrons generally have a nearly isotropic angular distribution and a power-law energy spectrum, J~E-β. The spectral index β ranges from ~1.5 to ~3.7, with an average of ~2.4. Both the superhalo power-law spectrum and anisotropy show no obvious correlation with sunspot number, solar flares, solar wind core population, etc. These superhalo electrons may form a quiet-time energetic electron background/reservoir in the IPM. They may originate from nonthermal processes related to the acceleration of solar wind, followed by scattering into isotropic angular distributions in the IPM. Another possibility is that superhalo electrons could be formed mainly due to acceleration by wave-particle interactions through the IPM.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The 2003 jerk has an abrupt change in the geomagnetic secular variation (SV), and was recognized as a local phenomenon of internal origin from the satellite observations (Olsen and Mandea, 2007). Notable strength of the 2003 jerk is located at Mid-Eastern Asia. The temporal and spatial features at this area are important to resolve the Earth's core fluid flow dynamics at local scale (e.g. Wardinski et al., 2008). We investigate the temporal-spatial development of the 2003 jerk in more detail at Mid-Eastern Asia with the ground-based observations and CHAOS-3 core field model. We select the data in the international geomagnetic quiet days to calculate the monthly means. In order to reduce the influence of the external field, we adopt a function comprising the terms associated with the indices of the geomagnetic activity, and the terms of the periodic signals on the observatory monthly means data (Stewart and Whaler, 1992). We then use an empirical AR-2 model to represent the internal field signals in the observatory data. The extreme detection is applied to identify the jerk in the SV time series. The onset time and the strength of the 2003 jerk are obtained through the detection for geomagnetic field component, X, Y and Z. The maximum of the strength of the 2003 jerk is located under the Indian mainland. The onset time of this jerk propagates approximately southeastward. Two jerks in 2001 and 2003 for the Z component are further compared and they are confirmed as independent processes. We suggest the jerk in 2001 identical to the well known 1999 jerk in Europe (Mandea et al., 2000). Our results reveal the fine structures of the 2003 jerk that corroborate the conclusions in previous studies. The larger scale time-spatial structure given by the AR-2 model constructed from ground observatory data (monthly values) is consistent with the results from the CHAOS-3 model. This structure can be applied for further inversion of the local core surface fluid flow motions

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

    NASA Astrophysics Data System (ADS)

    Gavryuseva, E.; Kroussanova, N.

    2002-12-01

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

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

    PubMed

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  18. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... Section III of the Guide provides information on establishing Pre-Rule Quiet Zones. A Pre-Rule Quiet Zone... differences between New and Pre-Rule Quiet Zones will be explained. Public Authority Designation and Public Authority Application to FRA methods also apply to Pre-Rule Quiet Zones. Section IV of the Guide deals...

  19. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... Section III of the Guide provides information on establishing Pre-Rule Quiet Zones. A Pre-Rule Quiet Zone... differences between New and Pre-Rule Quiet Zones will be explained. Public Authority Designation and Public Authority Application to FRA methods also apply to Pre-Rule Quiet Zones. Section IV of the Guide deals...

  20. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... Section III of the Guide provides information on establishing Pre-Rule Quiet Zones. A Pre-Rule Quiet Zone... differences between New and Pre-Rule Quiet Zones will be explained. Public Authority Designation and Public Authority Application to FRA methods also apply to Pre-Rule Quiet Zones. Section IV of the Guide deals...

  1. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Section III of the Guide provides information on establishing Pre-Rule Quiet Zones. A Pre-Rule Quiet Zone... differences between New and Pre-Rule Quiet Zones will be explained. Public Authority Designation and Public Authority Application to FRA methods also apply to Pre-Rule Quiet Zones. Section IV of the Guide deals...

  2. 49 CFR Appendix C to Part 222 - Guide to Establishing Quiet Zones

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... Section III of the Guide provides information on establishing Pre-Rule Quiet Zones. A Pre-Rule Quiet Zone... differences between New and Pre-Rule Quiet Zones will be explained. Public Authority Designation and Public Authority Application to FRA methods also apply to Pre-Rule Quiet Zones. Section IV of the Guide deals...

  3. Study of quiet turbofan STOL aircraft for short haul transportation

    NASA Technical Reports Server (NTRS)

    Higgins, T. P.; Stout, E. G.; Sweet, H. S.

    1973-01-01

    A study of quiet turbofan short takeoff aircraft for short haul air transportation was conducted. The objectives of the study were to: (1) define representative aircraft configurations, characteristics, and costs associated with their development, (2) identify critical technology and technology related problems to be resolved in successful introduction of representative short haul aircraft, (3) determine relationships between quiet short takeoff aircraft and the economic and social viability of short haul, and (4) identify high payoff technology areas.

  4. Models of the quiet and active solar atmosphere from Harvard OSO data.

    NASA Technical Reports Server (NTRS)

    Noyes, R. W.

    1971-01-01

    Review of some Harvard Observatory programs aimed at defining the physical conditions in quiet and active solar regions on the basis of data obtained from the OSO-IV and OSO-VI spacecraft. The spectral range covered is from 300 A to 1400 A. This spectral range consists of emission lines and continua from abundant elements such as hydrogen, helium, carbon, nitrogen, oxygen, silicon, magnesium, aluminum, neon, iron, and calcium in various ionization states ranging from neutral to 15 times ionized. The structure is discussed of the quiet solar atmosphere as deduced from center-to-limb behavior of spectral lines and continua formed in the chromosphere and corona. In reviewing investigations of solar active regions, it is shown that the structure of these regions varies in a complicated manner from point to point. The local structure is influenced by factors such as the magnetic field configuration within the active region and the age or evolutionary state of the region.

  5. STUDY OF CALIBRATION OF SOLAR RADIO SPECTROMETERS AND THE QUIET-SUN RADIO EMISSION

    SciTech Connect

    Tan, Chengming; Yan, Yihua; Tan, Baolin; Fu, Qijun; Liu, Yuying; Xu, Guirong

    2015-07-20

    This work presents a systematic investigation of the influence of weather conditions on the calibration errors by using Gaussian fitness, least chi-square linear fitness, and wavelet transform to analyze the calibration coefficients from observations of the Chinese Solar Broadband Radio Spectrometers (at frequency bands of 1.0–2.0 GHz, 2.6–3.8 GHz, and 5.2–7.6 GHz) during 1997–2007. We found that calibration coefficients are influenced by the local air temperature. Considering the temperature correction, the calibration error will reduce by about 10%–20% at 2800 MHz. Based on the above investigation and the calibration corrections, we further study the radio emission of the quiet Sun by using an appropriate hybrid model of the quiet-Sun atmosphere. The results indicate that the numerical flux of the hybrid model is much closer to the observation flux than that of other ones.

  6. On the Solar Quiet Variation Measured in Latin America by the Embrace Magnetometer Network

    NASA Astrophysics Data System (ADS)

    Denardini, Clezio Marcos; Moro, Juliano; Araujo Resende, Laysa Cristina; Chen, Sony Su

    2016-07-01

    The present work show the first results of the study about the seasonal variation of the Solar quiet (Sq) Earth's magnetic field based on magnetic measurements from the Embrace Magnetic Network (MagNet) at several latitudes in South America, covering the equatorial and low latitudinal region. For this study, we used data covering the period from September 2010 to December 2015, during the ascending phase of the solar cycle 24. Before analyzing the magnetic data collected from the Embrace Magnet, we compared the magnetic data collected by the Embrace variometer installed at Vassouras-RJ, in Brazil, with the same data collected by the absolute magnetometer installed by the Intermagnet at the same observatory. We show that our data is in pretty good agreement to the absolute values. With respect to the seasonal variation, we show clear seasonal modulation in all components, irrespective the latitude. The H component analysis revealed to have a seasonal dependence in both aspects: the duration of positive excursion along the day and the maximum amplitude. And the other components have also shown remarkable regional characteristic of the variation of the Sq. Finally, we take these results as the first steps towards developing a Sq model to be superimposed to International Geomagnetic Reference Field (IGRF) model as a useful tool for space weather forecast.

  7. Solar quiet current response in the African sector due to a 2009 sudden stratospheric warming event

    NASA Astrophysics Data System (ADS)

    Bolaji, O. S.; Oyeyemi, E. O.; Owolabi, O. P.; Yamazaki, Y.; Rabiu, A. B.; Okoh, D.; Fujimoto, A.; Amory-Mazaudier, C.; Seemala, G. K.; Yoshikawa, A.; Onanuga, O. K.

    2016-08-01

    We present solar quiet (Sq) variation of the horizontal (H) magnetic field intensity deduced from Magnetic Data Acquisition System (MAGDAS) records over Africa during an unusual strong and prolonged 2009 sudden stratospheric warming (SSW) event. A reduction in the SqH magnitude that enveloped the geomagnetic latitudes between 21.13°N (Fayum FYM) in Egypt and 39.51°S (Durban DRB) in South Africa was observed, while the stratospheric polar temperature was increasing and got strengthened when the stratospheric temperature reached its maximum. Another novel feature associated with the hemispheric reduction is the reversal in the north-south asymmetry of the SqH, which is indicative of higher SqH magnitude in the Northern Hemisphere compared to the Southern Hemisphere during SSW peak phase. The reversal of the equatorial electrojet (EEJ) or the counter electrojet (CEJ) was observed after the polar stratospheric temperature reached its maximum. The effect of additional currents associated with CEJ was observed in the Southern Hemisphere at middle latitude. Similar changes were observed in the EEJ at the South America, Pacific Ocean, and Central Asia sectors. The effect of the SSW is largest in the South American sector and smallest in the Central Asian sector.

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

    NASA Astrophysics Data System (ADS)

    Merline Matamba, Tshimangadzo; Bosco Habarulema, John

    2016-07-01

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

  9. Geomagnetic response to IMF and solar wind over different latitudes

    NASA Astrophysics Data System (ADS)

    Aslam, A. M.; Tripathi, Sharad Chandra; Mansoori, Azad Ahmad; Waheed, Malik Abdul

    2016-07-01

    In this paper a study on the response of geomagnetic field characteristics to the solar wind variation during three solar cycles (SC 21, SC 22, SC 23) have been conducted in a long term scale. The difference in the response of two different latitudinal characteristic indices has been investigated. For the purpose we have considered the high latitude index AE and the mid-latitude aa index and both gives the knowledge about the perturbations in the geomagnetic field conditions. Eventually we can infer the idea about the ionospheric current system changes in response to the solar wind conditions. The variation found in the AE and aa indices have been found to follow a 11 year cycle as similar to the sunspot variation. Also the correlation between the annual means of the solar wind parameters velocity V, magnetic filed B and the composite parameters BV and BV ^{2 } have been calculated . A difference was found between the correlations obtained for the AE and aa indices. We could also see that the difference in correlation follows a cyclic pattern i.e. the large difference is found during the solar maxima while a small difference is observed during the minima.

  10. Space radiation enhancement linked to geomagnetic disturbances.

    PubMed

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

    1997-12-01

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

  11. Space radiation enhancement linked to geomagnetic disturbances.

    PubMed

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

    1998-01-01

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

  12. Helio-geomagnetic influence in cardiological cases

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  13. Power lines and the geomagnetic field

    SciTech Connect

    Liboff, A.R.; McLeod, B.R.

    1995-09-01

    The metric of prime interest in power line epidemiological studies has been AC magnetic intensity. To consider also possible geomagnetic involvement, the orientation of a long straight power line is examined relative to a uniform geomagnetic field (GMF) with dip angle {alpha}. An expression is derived for the component of the total GMF that is parallel, at an elevation {beta}, to the circular magnetic field that surrounds the line. This component is a function of the angles {alpha} and {beta}, the total geomagnetic intensity B{sub T}, and the angle {theta} between the axis of the power line and magnetic north. Plotting these geomagnetic parameters for known leukemia residences allows one to test for possible ion cyclotron resonance or other GMF interactions. This approach, in principle, is an easy addition to existing or planned studies, because residential access is not required to obtain local values for {alpha}, {beta}, {theta}, and B{sub T}. The authors recommend including these parameters in the design of epidemiological studies examining power line fields and childhood leukemia.

  14. Aeroelastic Calculations of Quiet High- Speed Fan Performed

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Srivastava, Rakesh; Mehmed, Oral; Min, James B.

    2002-01-01

    An advanced high-speed fan was recently designed under a cooperative effort between the NASA Glenn Research Center and Honeywell Engines & Systems. The principal design goals were to improve performance and to reduce fan noise at takeoff. Scale models of the Quiet High-Speed Fan were tested for operability, performance, and acoustics. During testing, the fan showed significantly improved noise characteristics, but a self-excited aeroelastic vibration known as flutter was encountered in the operating range. Flutter calculations were carried out for the Quiet High-Speed Fan using a three-dimensional, unsteady aerodynamic, Reynolds-averaged Navier-Stokes turbomachinery code named "TURBO." The TURBO code can accurately model the viscous flow effects that can play an important role in various aeroelastic problems such as flutter with flow separation, flutter at high loading conditions near the stall line (stall flutter), and flutter in the presence of shock and boundary-layer interaction. Initially, calculations were performed with no blade vibrations. These calculations were at a constant rotational speed and a varying mass flow rate. The mass flow rate was varied by changing the backpressure at the exit boundary of the computational domain. These initial steady calculations were followed by aeroelastic calculations in which the blades were prescribed to vibrate harmonically in a natural mode, at a natural frequency, and with a fixed interblade phase angle between adjacent blades. The AE-prep preprocessor was used to interpolate the in-vacuum mode shapes from the structural dynamics mesh onto the computational fluid dynamics mesh and to smoothly propagate the grid deformations from the blade surface to the interior points of the grid. The aeroelastic calculations provided the unsteady aerodynamic forces on the blade surface due to blade vibrations. These forces were vector multiplied with the structural dynamic mode shape to calculate the work done on the blade during

  15. Incorporation of geomagnetic data and services into EPOS infrastructure

    NASA Astrophysics Data System (ADS)

    Hejda, Pavel; Chambodut, Aude; Curto, Juan-Jose; Flower, Simon; Kozlovskaya, Elena; Kubašta, Petr; Matzka, Jürgen; Tanskanen, Eija; Thomson, Alan

    2016-04-01

    Monitoring of the geomagnetic field has a long history across Europe that dates back to 1830', and is currently experiencing an increased interest within Earth observation and space weather monitoring. Our goals within EPOS-IP are to consolidate the community, modernise data archival and distribution formats for existing services and create new services for magnetotelluric data and geomagnetic models. Specific objectives are: • Enhance existing services providing geomagnetic data (INTERMAGNET- INTErnational Real-time MAGnetic observatory NETwork; World Data Centre for Geomagnetism; IMAGE- International Monitor for Auroral Geomagnetic Effects) and existing services providing geomagnetic indices (ISGI - International Service of Geomagnetic Indices). • Develop and enhance the geomagnetic community's metadata systems by creating a metadata database, filling it and putting in place processes to ensure that it is kept up to date in the future. • Develop and build access to magnetotelluric (MT) data including transfer functions and time series data from temporary, portable MT-arrays in Europe, as well as to lithospheric conductivity models derived from TM-data. • Develop common web and database access points to global and regional geomagnetic field and conductivity models. • Establish links from the geomagnetic data services, products and models to the Integrated Core Services. The immediate task in the current period is to identify data models of existing services, modify them and integrate into a common model of Geomagnetic Thematic Core Services.

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

    USGS Publications Warehouse

    Green, A.W.

    1990-01-01

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

  17. Convection Electric Field Patterns for Quiet and Disturbed Periods

    NASA Astrophysics Data System (ADS)

    Shepherd, S. G.; Cousins, E. D. P.

    2014-12-01

    Statistical models of ionospheric convection have been made using numeroustechniques and datasets. These models capture the climatology ofmagnetosphere-ionosphere coupling in the high-latitude and serve as usefulinputs to various models of the magnetosphere-ionosphere-theremosphere system.In this study, data from the Super Dual Auroral Radar Network (SuperDARN) areused to determine global-scale convection electric field patterns in thenorthern hemisphere for a variety of IMF and disturbance-level conditions.A five-year period from 2009-2013 has been chosen for this study and includesobservations that extend from the geomagnetic pole to below 50 degrees.Inclusion of data from mid-latitude and polar radars serves to augmentobservations from the 'traditional' high-latitude SuperDARN radars, extending the activity range over which global-scale patterns can be derived. Generally, a larger cross polar cap potential (CPCP) and linear dependence on the Kp index is observed in the new models, which is likely due to the more consistent observations in the polar cap and from the contribution of mid-latitude flows. Another notable difference in the new models is the extent to which westward flows are observed at lower latitudes. Sub-auroral flows and westward flows extending far into the post-midnight sector are observed at almost all activity levels. With the increased range of observations, these models represent an improvement in thedescription of ionospheric convection electric field climatology.

  18. Vertical characteristics of midlatitude E and F region ionospheric drifts during disturbed conditions..

    NASA Astrophysics Data System (ADS)

    Boska, Josef; Kouba, Daniel; Koucka Knizova, Petra; Potuznikova, Katerina

    2015-04-01

    Modern HF digisonde DPS-4 D (Digisonde Portable Sounder), which is in operation at the Pruhonice observatory of the Institute of Atmospheric Physics, Prague (IAP) from 2004, enables us to carry out standard ionospheric sounding and ionospheric drifts measurements. Using standard mode of automatic drift (autodrift mode) measurements the velocity of the F region drifts is usually determined in the vicinity of the peak of the electron density profile (N(h) profile). Since 2005 we are also measuring ionospheric drifts at the heights of the ionospheric E region. This new experimental arrangement makes possible to study vertical changes and profiles of the ionospheric drift velocity in two different ionospheric regions. From E region within the altitudinal interval of 90-150 km to F region in altitudes from 150 km up to height of the maximum electron density profile N(h). This paper present the results of the analysis of the plasma drifts velocity in two different ionospheric regions observed under quiet geomagnetic and ionospheric conditions and especially during ionospheric spread F conditions. These spread F conditions are often observed in the ionosphere as effect of travelling ionopheric disturbances TIDs. The presence of this TIDS can be detected from the F layer isoelectrondensity contours. The spread F conditions are often present also under moderate-to-intense ionospheric and geomagnetic storm conditions. Our results shows, that behavior of Es layer drifts can be different than drifts in E-layer. During winter geomagnetic storm -more dramatic increasing of all drift velocities components was observed (50 - 100 m/s vertical drift component). Different behaviour ionospheric drifts at the heights intervals 90 - 110 km and 110 - 130 km was observed during winter storm. Significant height changes of the drift velocity height profile in the interval of heights 90 - 130 km during winter event was observed. Our results shows that behavior of Es layer drifts can be

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

    PubMed

    Gmitrov, Juraj; Ohkubo, Chiyoji

    2002-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Babayev, Elchin S.; Allahverdiyeva, Aysel A.

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

  5. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.41 How does this rule affect Pre-Rule Quiet Zones and Pre-Rule... public highway-rail grade crossing within the quiet zone one or more SSMs identified in appendix A...

  6. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.41 How does this rule affect Pre-Rule Quiet Zones and Pre-Rule... public highway-rail grade crossing within the quiet zone one or more SSMs identified in appendix A...

  7. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.41 How does this rule affect Pre-Rule Quiet Zones and Pre-Rule... public highway-rail grade crossing within the quiet zone one or more SSMs identified in appendix A...

  8. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.41 How does this rule affect Pre-Rule Quiet Zones and Pre-Rule... public highway-rail grade crossing within the quiet zone one or more SSMs identified in appendix A...

  9. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS Exceptions to the Use of the Locomotive Horn Silenced Horns at Groups of Crossings-Quiet Zones § 222.41 How does this rule affect Pre-Rule Quiet Zones and Pre-Rule... public highway-rail grade crossing within the quiet zone one or more SSMs identified in appendix A...

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  11. Quiet Clean Short-haul Experimental Engine (QCSEE). Double-annular clean combustor technology development report

    NASA Technical Reports Server (NTRS)

    Bahr, D. W.; Burrus, D. L.; Sabla, P. E.

    1979-01-01

    A sector combustor technology development program was conducted to define an advanced double annular dome combustor sized for use in the quiet clean short haul experimental engine (QCSEE). A design which meets the emission goals, and combustor performance goals of the QCSEE engine program was developed. Key design features were identified which resulted in substantial reduction in carbon monoxide and unburned hydrocarbon emission levels at ground idle operating conditions, in addition to very low nitric oxide emission levels at high power operating conditions. Their significant results are reported.

  12. A Combined Solar and Geomagnetic Index for Thermospheric Climate

    NASA Technical Reports Server (NTRS)

    Hunt, Linda; Mlynczak, Marty

    2015-01-01

    Infrared radiation from nitric oxide (NO) at 5.3 Â is a primary mechanism by which the thermosphere cools to space. The SABER instrument on the NASA TIMED satellite has been measuring thermospheric cooling by NO for over 13 years. Physically, changes in NO emission are due to changes in temperature, atomic oxygen, and the NO density. These physical changes however are driven by changes in solar irradiance and changes in geomagnetic conditions. We show that the SABER time series of globally integrated infrared power (Watts) radiated by NO can be replicated accurately by a multiple linear regression fit using the F10.7, Ap, and Dst indices. This fit enables several fundamental properties of NO cooling to be determined as well as their variability with time, permitting reconstruction of the NO power time series back nearly 70 years with extant databases of these indices. The relative roles of solar ultraviolet and geomagnetic processes in determining the NO cooling are derived and shown to be solar cycle dependent. This reconstruction provides a long-term time series of an integral radiative constraint on thermospheric climate that can be used to test climate models.

  13. Ionospheric Response During Four Intense Geomagnetic Storms: Similarities and Differences

    NASA Astrophysics Data System (ADS)

    Mannucci, A. J.; Tsurutani, B. T.; Crowley, G.; Verkhoglyadova, O. P.

    2007-05-01

    Large magnitude and hemispheric-scale increases in ionospheric plasma content are observed for daytime local times during intense geomagnetic storms. Ionospheric increases during the main phase of geomagnetic storms were identified many years ago and categorized as the "positive phase" ionospheric response. This talk will explore what we can learn using satellite data and distributed ground-based measurements, to understand the geoeffective processes at work in creating the positive phase for intense storms. The importance of electric fields penetrating to low latitudes on the dayside has received a great deal of attention recently, and is leading to revised theoretical and modeling constructs to account for the observations in a quantitative manner. We will present ground and space-based Global Positioning System (GPS) electron content data for four storms and analyze the data in light of the upstream conditions with a common epoch analysis. Modeling studies of the storm-time ionospheric behavior will be shown, using the ASPEN-TIMEGCM fully-coupled thermosphere- ionosphere (T-I) model with low-latitude electrodynamics. The ASPEN-TIMEGCM model contains storm-time effects such as winds and the resulting dynamo electric fields, but penetration E-fields including shielding are not currently included. The model runs are driven by carefully reconstructed high latitude time-dependent drivers based in part on the AMIE high latitude electrodynamics model. The time history of a modeled storm will be compared with observations. We will highlight outstanding science questions that are revealed in this study.

  14. Geomagnetically induced currents in Uruguay: Sensitivity to modelling parameters

    NASA Astrophysics Data System (ADS)

    Caraballo, R.

    2016-11-01

    According to the traditional wisdom, geomagnetically induced currents (GIC) should occur rarely at mid-to-low latitudes, but in the last decades a growing number of reports have addressed their effects on high-voltage (HV) power grids at mid-to-low latitudes. The growing trend to interconnect national power grids to meet regional integration objectives, may lead to an increase in the size of the present energy transmission networks to form a sort of super-grid at continental scale. Such a broad and heterogeneous super-grid can be exposed to the effects of large GIC if appropriate mitigation actions are not taken into consideration. In the present study, we present GIC estimates for the Uruguayan HV power grid during severe magnetic storm conditions. The GIC intensities are strongly dependent on the rate of variation of the geomagnetic field, conductivity of the ground, power grid resistances and configuration. Calculated GIC are analysed as functions of these parameters. The results show a reasonable agreement with measured data in Brazil and Argentina, thus confirming the reliability of the model. The expansion of the grid leads to a strong increase in GIC intensities in almost all substations. The power grid response to changes in ground conductivity and resistances shows similar results in a minor extent. This leads us to consider GIC as a non-negligible phenomenon in South America. Consequently, GIC must be taken into account in mid-to-low latitude power grids as well.

  15. Driving Plasmaspheric Electron Density Simulations During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed

    Olson, P

    2007-12-18

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

  17. Natural variability of atmospheric temperatures and geomagnetic intensity over a wide range of time scales

    PubMed Central

    Pelletier, Jon D.

    2002-01-01

    The majority of numerical models in climatology and geomagnetism rely on deterministic finite-difference techniques and attempt to include as many empirical constraints on the many processes and boundary conditions applicable to their very complex systems. Despite their sophistication, many of these models are unable to reproduce basic aspects of climatic or geomagnetic dynamics. We show that a simple stochastic model, which treats the flux of heat energy in the atmosphere by convective instabilities with random advection and diffusive mixing, does a remarkable job at matching the observed power spectrum of historical and proxy records for atmospheric temperatures from time scales of one day to one million years (Myr). With this approach distinct changes in the power-spectral form can be associated with characteristic time scales of ocean mixing and radiative damping. Similarly, a simple model of the diffusion of magnetic intensity in Earth's core coupled with amplification and destruction of the local intensity can reproduce the observed 1/f noise behavior of Earth's geomagnetic intensity from time scales of 1 (Myr) to 100 yr. In addition, the statistics of the fluctuations in the polarity reversal rate from time scales of 1 Myr to 100 Myr are consistent with the hypothesis that reversals are the result of variations in 1/f noise geomagnetic intensity above a certain threshold, suggesting that reversals may be associated with internal fluctuations rather than changes in mantle thermal or magnetic boundary conditions. PMID:11875208

  18. Natural variability of atmospheric temperatures and geomagnetic intensity over a wide range of time scales.

    PubMed

    Pelletier, Jon D

    2002-02-19

    The majority of numerical models in climatology and geomagnetism rely on deterministic finite-difference techniques and attempt to include as many empirical constraints on the many processes and boundary conditions applicable to their very complex systems. Despite their sophistication, many of these models are unable to reproduce basic aspects of climatic or geomagnetic dynamics. We show that a simple stochastic model, which treats the flux of heat energy in the atmosphere by convective instabilities with random advection and diffusive mixing, does a remarkable job at matching the observed power spectrum of historical and proxy records for atmospheric temperatures from time scales of one day to one million years (Myr). With this approach distinct changes in the power-spectral form can be associated with characteristic time scales of ocean mixing and radiative damping. Similarly, a simple model of the diffusion of magnetic intensity in Earth's core coupled with amplification and destruction of the local intensity can reproduce the observed 1/f noise behavior of Earth's geomagnetic intensity from time scales of 1 (Myr) to 100 yr. In addition, the statistics of the fluctuations in the polarity reversal rate from time scales of 1 Myr to 100 Myr are consistent with the hypothesis that reversals are the result of variations in 1/f noise geomagnetic intensity above a certain threshold, suggesting that reversals may be associated with internal fluctuations rather than changes in mantle thermal or magnetic boundary conditions. PMID:11875208

  19. Comparison of electron concentrations in the ionospheric E-layer maximum in spring conditions obtained by calculations and Moscow ionosonde measurements

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    The electron concentrations in the ionospheric E-layer maximum NmE, as measured by the Moscow ionosonde, are compared with the results of theoretical calculations of NmE for geomagnetically quiet conditions at low solar activity on April 1, 1986, and April 6, 1996, moderate solar activity on April 9, 1978, and April 6, 1998, and high solar activity on April 20, 1980, and April 15, 1991. On the basis of this comparison, a correction of the model flux of solar X-ray radiation is proposed. The discovered variability of the correction factors manifests the influence of solar X-ray radiation flux variations on NmE variability. The dependence of the influence of the neutral constituents ionization by photoelectrons on NmE on the solar activity level is studied.

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

    NASA Technical Reports Server (NTRS)

    Voorhies, Coerte V.

    1992-01-01

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

  1. Geomagnetic Indices Variations And Human Physiology

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.

    2007-12-01

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

  2. Review of selected geomagnetic activity indices

    NASA Technical Reports Server (NTRS)

    Allen, J. H.; Feynman, J.

    1979-01-01

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

  3. Quiet Sonic Booms: A NASA and Industry Progress Report

    NASA Technical Reports Server (NTRS)

    Larson, David Nils; Martin, Roy; Haering, Edward A.

    2011-01-01

    The purpose of this Oral Presentation is to present a progress report on NASA and Industry efforts related to Quiet Sonic Boom Program activities. This presentation will review changes in aircraft shaping to produce quiet supersonic booms and associated supersonic flight test methods and results. In addition, new flight test profiles have been recently developed that have allowed for the generation of sonic booms of varying intensity. These new flight test profiles have allowed for ground testing of the response of various building structures to sonic booms and the associated public acceptability to various sonic boom intensities. The new flight test profiles and associated ground measurement test methods will be reviewed. Finally, this Oral Presentation will review the International Regulatory requirements that would be involved to change aviation regulation and allow for overland quiet supersonic flight.

  4. Influence of geomagnetic disturbance on atmospheric circulation

    NASA Technical Reports Server (NTRS)

    Kodera, K.

    1985-01-01

    The influence of geomagnetic disturbance or passage of the solar sector boundary on the atmospheric circulation was reported. Unfortunately little is known about the general morphology of Sun weather relationships. In order to know the general characteristics, pressure height variations on an isobaric surface over the Northern Hemisphere were analyzed. Although it may be suitable to use some index, or some integrated value for statistical purposes, weather prediction data were used to verify whether the obtained tropospheric response is caused externally or not.

  5. MAGSAT for geomagnetic studies over Indian region

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  6. All Quiet on the Postmodern Front?

    ERIC Educational Resources Information Center

    Edwards, Richard

    2006-01-01

    This paper explores the question of the purpose of education within the context of Lyotard's framing of the postmodern condition. It points to some of the continuities and discontinuities in the framing of the current condition as postmodern and the recurrent problematics of truth-telling which is the mark of this condition. It suggests that…

  7. Geomagnetic effects on the average surface temperature

    NASA Astrophysics Data System (ADS)

    Ballatore, P.

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

  8. Domino model for geomagnetic field reversals.

    PubMed

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

    2013-01-01

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

  9. The Vector Matching Method in Geomagnetic Aiding Navigation

    PubMed Central

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

    2016-01-01

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

  10. The Vector Matching Method in Geomagnetic Aiding Navigation.

    PubMed

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

    2016-01-01

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

  11. An evidence for prompt electric field disturbance driven by changes in the solar wind density under northward IMF Bz condition

    NASA Astrophysics Data System (ADS)

    Rout, Diptiranjan; Chakrabarty, D.; Sekar, R.; Reeves, G. D.; Ruohoniemi, J. M.; Pant, Tarun K.; Veenadhari, B.; Shiokawa, K.

    2016-05-01

    Before the onset of a geomagnetic storm on 22 January 2012 (Ap = 24), an enhancement in solar wind number density from 10/cm3 to 22/cm3 during 0440-0510 UT under northward interplanetary magnetic field (IMF Bz) condition is shown to have enhanced the high-latitude ionospheric convection and also caused variations in the geomagnetic field globally. Conspicuous changes in ΔX are observed not only at longitudinally separated low-latitude stations over Indian (prenoon), South American (midnight), Japanese (afternoon), Pacific (afternoon) and African (morning) sectors but also at latitudinally separated stations located over high and middle latitudes. The latitudinal variation of the amplitude of the ΔX during 0440-0510 UT is shown to be consistent with the characteristics of prompt penetration electric field disturbances. Most importantly, the density pulse event caused enhancements in the equatorial electrojet strength and the peak height of the F layer (hmF2) over the Indian dip equatorial sector. Further, the concomitant enhancements in electrojet current and F layer movement over the dip equator observed during this space weather event suggest a common driver of prompt electric field disturbance at this time. Such simultaneous variations are found to be absent during magnetically quiet days. In absence of significant change in solar wind velocity and magnetospheric substorm activity, these observations point toward perceptible prompt electric field disturbance over the dip equator driven by the overcompression of the magnetosphere by solar wind density enhancement.

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

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

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

  13. Larger center of pressure minus center of gravity in the elderly induces larger body acceleration during quiet standing.

    PubMed

    Masani, Kei; Vette, Albert H; Kouzaki, Motoki; Kanehisa, Hiroaki; Fukunaga, Tetsuo; Popovic, Milos R

    2007-07-18

    When an inverted pendulum approximates quiet standing, it is assumed that the distance between the center of pressure and the vertical projection of the center of mass on the ground (COP-COG) reflects the relationship between the controlling and controlled variables of the balance control mechanism, and that the center of mass acceleration (ACC) is proportional to COP-COG. As aging affects the control mechanism of balance during quiet standing, COP-COG must be influenced by aging and, as a result, ACC is influenced by aging as well. The purpose of this study was to test the hypotheses that aging results in an increased COP-COG amplitude and, as a consequence, that ACC becomes larger in the elderly than the young. Fifteen elderly and 11 young subjects stood quietly on a force platform with their eyes open or closed. We found that (1) the standard deviations of COP-COG and ACC were larger in the elderly than in the young, irrespective of the eye condition; (2) COP-COG is proportional to ACC in both age groups, i.e., the inverted pendulum assumption holds true for quiet standing. The results suggest that a change in the control strategy that is due to aging causes a larger COP-COG in the elderly and, as a consequence, that ACC becomes larger as well.

  14. The Lewis Research Center geomagnetic substorm simulation facility. [its function in determining the response of spacecraft materials

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  15. Quiet eye training facilitates competitive putting performance in elite golfers.

    PubMed

    Vine, Samuel J; Moore, Lee J; Wilson, Mark R

    2011-01-01

    The aim of this study was to examine the effectiveness of a brief quiet eye (QE) training intervention aimed at optimizing visuomotor control and putting performance of elite golfers under pressure, and in real competition. Twenty-two elite golfers (mean handicap 2.7) recorded putting statistics over 10 rounds of competitive golf before attending training individually. Having been randomly assigned to either a QE training or Control group, participants were fitted with an Applied Science Laboratories Mobile Eye tracker and performed 20 baseline (pre-test) putts from 10 ft. Training consisted of video feedback of their gaze behavior while they completed 20 putts; however the QE-trained group received additional instructions related to maintaining a longer QE period. Participants then recorded their putting statistics over a further 10 competitive rounds and re-visited the laboratory for retention and pressure tests of their visuomotor control and putting performance. Overall, the results were supportive of the efficacy of the QE training intervention. QE duration predicted 43% of the variance in putting performance, underlying its critical role in the visuomotor control of putting. The QE-trained group maintained their optimal QE under pressure conditions, whereas the Control group experienced reductions in QE when anxious, with subsequent effects on performance. Although their performance was similar in the pre-test, the QE-trained group holed more putts and left the ball closer to the hole on missed putts than their Control group counterparts in the pressure test. Importantly, these advantages transferred to the golf course, where QE-trained golfers made 1.9 fewer putts per round, compared to pre-training, whereas the Control group showed no change in their putting statistics. These results reveal that QE training, incorporated into a pre-shot routine, is an effective intervention to help golfers maintain control when anxious.

  16. 77 FR 24952 - Staff Technical Conference on Geomagnetic Disturbances to the Bulk-Power System; Technical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Staff Technical Conference on Geomagnetic Disturbances to the Bulk-Power... geomagnetic disturbances. The conference will explore the risks and impacts from geomagnetically...

  17. Study of Ring Current Dynamics During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

    Jordanova, Vania K.

    2000-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Mustajab, Fainana

    2016-07-01

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

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

    PubMed

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    PubMed

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

    2014-07-01

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

  2. Contemplative Pedagogy: A Quiet Revolution in Higher Education

    ERIC Educational Resources Information Center

    Zajonc, Arthur

    2013-01-01

    During the last fifteen years a quiet pedagogical revolution has taken place in colleges, universities, and community colleges across the United States and increasingly around the world. Often flying under the name "contemplative pedagogy," it offers to its practitioners a wide range of educational methods that support the development of student…

  3. On the hazard of quiet vehicles to pedestrians and drivers.

    PubMed

    Wogalter, Michael S; Lim, Raymond W; Nyeste, Patrick G

    2014-09-01

    The need to produce more efficient and less polluting vehicles has encouraged mass production of alternative energy vehicles, such as hybrid and electric cars. Many of these vehicles are capable of very quiet operation. While reducing noise pollution is desirable, quieter vehicles could negatively affect pedestrian safety because of reduced sound cues compared to louder internal combustion engines. Three studies were performed to investigate people's concern about this issue. In Study 1, a questionnaire completed by 378 people showed substantial positive interest in quiet hybrid and electric cars. However, they also indicated concern about the reduced auditory cues of quiet vehicles. In Study 2, 316 participants rated 14 sounds that could be potentially added to quiet alternative-energy vehicles. The data showed that participants did not want annoying sounds, but preferred adding "engine" and "hum" sounds relative to other types of sounds. In Study 3, 24 persons heard and rated 18 actual sounds within 6 categories that were added to a video of a hybrid vehicle driving by. The sounds most preferred were "engine" followed by "white noise" and "hum". Implications for adding sounds to facilitate pedestrians' detection of moving vehicles and for aiding drivers' awareness of speed are discussed. PMID:24035347

  4. Quiet Times: The Place for Sadness in Growing Up.

    ERIC Educational Resources Information Center

    Peter, Val J.

    1999-01-01

    Compares clinical depression with reactive depression, a normal part of childhood development. Looks at quiet times children may experience, and provides examples of how normal childhood sadness can turn into depression. Suggests coping mechanisms and support structures that can prevent this cycle from occurring. (Author/JDM)

  5. On the hazard of quiet vehicles to pedestrians and drivers.

    PubMed

    Wogalter, Michael S; Lim, Raymond W; Nyeste, Patrick G

    2014-09-01

    The need to produce more efficient and less polluting vehicles has encouraged mass production of alternative energy vehicles, such as hybrid and electric cars. Many of these vehicles are capable of very quiet operation. While reducing noise pollution is desirable, quieter vehicles could negatively affect pedestrian safety because of reduced sound cues compared to louder internal combustion engines. Three studies were performed to investigate people's concern about this issue. In Study 1, a questionnaire completed by 378 people showed substantial positive interest in quiet hybrid and electric cars. However, they also indicated concern about the reduced auditory cues of quiet vehicles. In Study 2, 316 participants rated 14 sounds that could be potentially added to quiet alternative-energy vehicles. The data showed that participants did not want annoying sounds, but preferred adding "engine" and "hum" sounds relative to other types of sounds. In Study 3, 24 persons heard and rated 18 actual sounds within 6 categories that were added to a video of a hybrid vehicle driving by. The sounds most preferred were "engine" followed by "white noise" and "hum". Implications for adding sounds to facilitate pedestrians' detection of moving vehicles and for aiding drivers' awareness of speed are discussed.

  6. The importance of Radio Quiet Zone (RQZ) for radio astronomy

    NASA Astrophysics Data System (ADS)

    Umar, Roslan; Abidin, Zamri Zainal; Ibrahim, Zainol Abidin

    2013-05-01

    Most of radio observatories are located in isolated areas. Since radio sources from the universe is very weak, astronomer need to avoid radio frequency interference (RFI) from active spectrum users and radio noise produced by human made (telecommunication, mobile phone, microwave user and many more. There are many observatories around the world are surrounded by a Radio Quiet Zone (RQZ), which is it was set up using public or state laws. A Radio Quiet Zone normally consists of two areas: an exclusive area in which totally radio emissions are forbidden, with restrictions for residents and business developments, and a larger (radius up to 100 km above) coordination area where the power of radio transmission limits to threshold levels. Geographical Information System (GIS) can be used as a powerful tool in mapping large areas with varying RQZ profiles. In this paper, we report the initial testing of the usage of this system in order to identify the areas were suitable for Radio Quiet Zone. Among the important parameters used to develop the database for our GIS are population density, information on TV and telecommunication (mobile phones) transmitters, road networks (highway), and contour shielding. We will also use other information gathered from on-site RFI level measurements on selected 'best' areas generated by the GIS. The intention is to find the best site for the purpose of establishing first radio quiet zones for radio telescope in Malaysia.

  7. The Reform Movement and the Quiet Crisis in Gifted Education.

    ERIC Educational Resources Information Center

    Renzulli, Joseph S.; Reis, Sally M.

    1991-01-01

    Gifted education faces a quiet crisis as reform movements focus on cosmetic administrative changes in school organization and management rather than interaction among teachers, students, and the material to be learned. Two goals of American education are presented: providing the best possible education to promising students and improving the…

  8. Design note about a 75 KVA quiet power distribution system

    SciTech Connect

    Visser, A.T.

    1984-04-05

    This note describes a 75KVA quiet power distribution system for X 653 in neutrino Lab D. It is fed from the regular AC distribution which exists in the building and it has no standby power. Its purpose is to remove electrical disturbances which are present on the regular AC distribution.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  10. Characterization and diagnostic methods for geomagnetic auroral infrasound waves

    NASA Astrophysics Data System (ADS)

    Oldham, Justin J.

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

  11. Geomagnetic imprint of the Persani volcanism

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    USGS Publications Warehouse

    Peddie, N.W.

    1992-01-01

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

  13. When Talking Is Better Than Staying Quiet

    NASA Astrophysics Data System (ADS)

    Lasry, Nathaniel; Charles, Elizabeth; Whittaker, Chris; Lautman, Michael

    2009-11-01

    The effectiveness of Peer Instruction is often associated to the importance of in-class discussions between peers. Typically, a greater number of students have correct answers after peer discussions. However, other cognitive and metacognitive processes such as reflection or time-on-task may also explain this increase because students answering conceptual questions reflect more and spend more time thinking about their understanding. An identical sequence of conceptual questions was given to three groups of students. All groups were polled twice on each question. Between polls, students were asked either to discuss their choice with a peer, or to reflect for a minute (no discussion), or were given a distraction task (sequence of cartoons: no discussion and no reflection). Increases in the rates of correct answers between the first and the second poll were found across all conditions. The `Distract' condition had a small but positive increase (3.4%). The `Reflect' condition had a greater increase (9.7%) while the `Discuss' condition had the greatest (21.0%). All conditions showed gains, possibly because of `testing effects', though peer-discussions clearly yield greatest increases. Our findings show that learning gains through peer discussions cannot be explained only by additional time-on-task or self-reflection.

  14. Geomagnetic field effect on cardiovascular regulation.

    PubMed

    Gmitrov, Juraj; Gmitrova, Anna

    2004-02-01

    The goal of the present research was try to explain the physiological mechanism for the influence of the geomagnetic field (GMF) disturbance, reflected by the indices of the geomagnetic activity (K, K(p), A(k), and A(p) indices), on cardiovascular regulation. One hundred forty three experimental runs (one daily) comprising 50 min hemodynamic monitoring sequences were carried out in rabbits sedated by pentobarbital infusion (5 mg/kg/h). We examined the arterial baroreflex effects on the short term blood pressure and heart rate (HR) variabilities reflected by the standard deviation (SD) of the average values of the mean femoral arterial blood pressure (MAP) and the HR. Baroreflex sensitivity (BRS) was estimated from blood pressure/HR response to intravenous (i.v.) bolus injections of vasoconstrictor (phenylephrine) and vasodilator (nitroprusside) drugs. We found a significant negative correlation of increasing GMF disturbance (K(p)) with BRS (P = 0.008), HR SD (P =0.022), and MAP SD (P = 0.002) signifying the involvement of the arterial baroreflex mechanism. The abrupt change in geomagnetic disturbance from low (K = 0) to high (K = 4-5) values was associated with a significant increase in MAP (83 +/- 5 vs. 99 +/- 5 mm Hg, P = 0.045) and myocardial oxygen consumption, measured by MAP and HR product (24100 +/- 1800 vs. 31000 +/- 2500 mm Hg. bpm, P = 0.034), comprising an additional cardiovascular risk. Most likely, GMF affects brainstem and higher neural cardiovascular regulatory centers modulating blood pressure and HR variabilities associated with the arterial baroreflex. PMID:14735558

  15. Geomagnetic field modeling by optimal recursive filtering

    NASA Technical Reports Server (NTRS)

    1980-01-01

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

  16. Geomagnetically Induced Currents: Progress and Issues

    NASA Astrophysics Data System (ADS)

    Thomson, Alan

    2010-05-01

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

  17. Advanced Theory of Deep Geomagnetic Sounding

    NASA Astrophysics Data System (ADS)

    Chave, Alan D.

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  19. Using different pseudorange measurements to evaluate the performance of GPS-based navigation systems during Geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Adewale, Adekola; Oyeyemi, Elijah

    2016-07-01

    The space and ground-based Global Positioning System (GPS) are vulnerable to a variety of space weather effects, particularly effects due to geomagnetic storms, and as such, signals from the systems suffer degradation during propagation through the ionosphere. A comparison of GPS positioning 3-D vertical (MRSE) and horizontal (DRMS) root mean square positioning errors obtained from different pseudorange measurements at low and high latitude stations has been done. GPS observation data were processed and analyzed from 6th-12th November, 2004, using different pseudorange measurements i.e., L1 C/A, L1 P, L2 P codes and ionosphere-free combination ((C/A on L1 and P on L2) and (P on L1 and P on L2)). Our results show that geomagnetic storms have impact on navigation at low and high latitude stations. This work also shows that GPS receivers can record significant positioning error during magnetically quiet days and with ionosphere-free pseudorange measurement.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  1. Observations of high-latitude geomagnetic field fluctuations during St. Patrick's Day storm: Swarm and SuperDARN measurements

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    The aim of this work is to study the properties of the magnetic field's fluctuations produced by ionospheric and magnetospheric electric currents during the St. Patrick's Day geomagnetic storm (17 March 2015). We analyse the scaling features of the external contribution to the horizontal geomagnetic field recorded simultaneously by the three satellites of the Swarm constellation during a period of 13 days (13-25 March 2015). We examine the different latitudinal structure of the geomagnetic field fluctuations and analyse the dynamical changes in the magnetic field scaling features during the development of the geomagnetic storm. Analysis reveals consistent patterns in the scaling properties of magnetic fluctuations and striking changes between the situation before the storm, during the main phase and recovery phase. We discuss these dynamical changes in relation to those of the overall ionospheric polar convection and potential structures as reconstructed using SuperDARN data. Our findings suggest that distinct turbulent regimes characterised the mesoscale magnetic field's fluctuations and that some factors, which are known to influence large-scale fluctuations, have also an influence on mesoscale fluctuations. The obtained results are an example of the capability of geomagnetic field fluctuations data to provide new insights about ionospheric dynamics and ionosphere-magnetosphere coupling. At the same time, these results could open doors for development of new applications where the dynamical changes in the scaling features of the magnetic fluctuations are used as local indicators of magnetospheric conditions.

  2. Search for correlation between geomagnetic disturbances and mortality

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  3. [Exacerbation of hypertension and disturbances of the geomagnetic field].

    PubMed

    Vershinina, N I; Petrochenko, N A; Shumilov, I S

    1997-01-01

    The authors consider relationships between emergence of acute episodes of essential hypertension (hospital admittances) and disturbance of the geomagnetic field. The authors report male- and female-specific ranges of the geomagnetic field variations which are threatening for hypertensive subjects. PMID:9229606

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

    NASA Astrophysics Data System (ADS)

    Tiwari, Bhupendra Kumar

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  6. Jerks as chaotic fluctuations of the geomagnetic field

    NASA Astrophysics Data System (ADS)

    Qamili, Enkelejda; De Santis, Angelo; Isac, Anca; Mandea, Mioara; Duka, Bejo; Simonyan, Anahit

    2013-04-01

    The geomagnetic field is chaotic and can be characterised by a mean exponential time scale < ? > of around 6 years after which it is no longer predictable. It is also ergodic, so time analyses can substitute the more difficult phase space analyses. Taking advantage of these two properties of the geomagnetic field, a scheme of processing global geomagnetic models in time is presented, in order to estimate fluctuations of the time scale. Considering that the capability to predict the geomagnetic field is reduced over periods of geomagnetic jerks, here we propose a method to detect these events over a long time-span. This approach considers that epochs characterised by relative minima of fluctuations in time scale ?, i.e., those periods when the geomagnetic field is less predictable, are possible jerk occurrence dates. We analyse the last 400 years of the geomagnetic field (covered by the Gufm1 model) to detect minima of fluctuations, i.e., epochs characterised by lower values of the time scale. Through this method, most of the well known jerks are confirmed and a few others have been detected. Finally we also identify some short periods when the field is less chaotic (more predictable) than usual, naming these as periods of steady-state geomagnetic regime, to underline their opposite behaviour with respect to jerks.

  7. Empirical analytic transformations between geographic and corrected geomagnetic coordinates

    NASA Technical Reports Server (NTRS)

    Comfort, R. H.

    1970-01-01

    Based upon a mathematical model of contours of constant corrected geomagnetic latitude in a polar projection of geographic coordinates, analytic equations are developed for converting geographic coordinates to corrected geomagnetic coordinates and vice versa. The equations were programmed for use on a small computer. This treatment is restricted to the Northern Hemisphere.

  8. Geomagnetic disturbances imprints in ground and satellite altitude observatories

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  9. Difference at chromospheric levels between rs cvn-type binaries, active and quiet chromosphere single stars, and active and quiet regions in the sun

    SciTech Connect

    Linsky, J.L.

    1980-01-01

    This paper summarizes the differences in the properties of active chromospheres compared with quiet chromospheres by comparing active and quiet regions on the Sun, active and quiet chromosphere stars, and the very active chromospheres seen in close binary systems with chromospheres of single stars. In particular, the chromospheres of the RS CVn-type binary systems UX Arietis and HR 1099 and the chromosphere of UX Arietis during a flare are modeled.

  10. How to Design a Quiet School.

    ERIC Educational Resources Information Center

    The American School Board Journal, 1968

    1968-01-01

    Problems of sound insulation and control particularly in areas where there is a high level in exterior noise conditions, resulted in this study to determine approaches to sound control in school construction. After a general discussion of noise problems in school districts and teaching situations, two examples of sound control solutions are…

  11. Avalanches at the Core-Mantle Boundary: Possible Role in Geomagnetic Reversals, Mantle Plumes, and Superchrons

    NASA Astrophysics Data System (ADS)

    Muller, R. A.; Levine, J.; Rohde, R.

    2002-12-01

    Avalanches at the core-mantle boundary have not been directly observed, but if they exist they could affect many geophysical phenomena. Avalanches occur in ?sediment? accumulating on the inner surface of the mantle (according to the theory of Buffett et al.). Because the sediment is not evenly deposited, avalanches could provide the primary mechanism to redistribute sedimentary material evenly over the core-mantle boundary. Core-mantle avalanches, like turbidity flows in the ocean, consist of both solid material and entrained liquid. Such flows can occur at shallow angles (less than a few degrees) and could continue for many kilometers or hundreds of kilometers, depending on the topography. However, these avalanches are upside-down: they flow upward, propelled by buoyancy, into inverted valleys on the mantle surface. The avalanches mix relatively cool sediment with hot liquid iron, creating a redistribution of heat near the boundary. If the avalanche is sufficiently thick (100 m) then the cold pulse will create a downward plume in the core which can disrupt the convective cells that maintain the Earth?s dipole field. When the cells reestablish, the result is a geomagnetic reversal or excursion. We predict a reversal pattern different from that of the chaotic reversals seen in simulations by Glatzmeier. Avalanche-triggered reversals begin with a rapid drop in the dipole moment (but with higher order moments increasing), followed by a period with low dipole moment lasting from hundreds to thousands of years, followed by a rapid build-up of the reversed dipole field. Studies of the detailed time structure of reversals can test the model. As with turbidity flows, we expect a spectrum of avalanche sizes. The largest avalanches are the least probable. The sudden removal of a sediment blanket exposes the lower mantle to a pulse of heat, and for sufficiently large avalanches (>> 100 meters thick) this can contribute to the conditions needed for a mantle plume. A large

  12. F-15B Quiet Spike(TradeMark) Aeroservoelastic Flight-Test Data Analysis

    NASA Technical Reports Server (NTRS)

    Kukreja, Sunil L.

    2007-01-01

    System identification is utilized in the aerospace community for development of simulation models for robust control law design. These models are often described as linear, time-invariant processes and assumed to be uniform throughout the flight envelope. Nevertheless, it is well known that the underlying process is inherently nonlinear. Over the past several decades the controls and biomedical communities have made great advances in developing tools for the identification of nonlin ear systems. In this report, we show the application of one such nonlinear system identification technique, structure detection, for the an alysis of Quiet Spike(TradeMark)(Gulfstream Aerospace Corporation, Savannah, Georgia) aeroservoelastic flight-test data. Structure detectio n is concerned with the selection of a subset of candidate terms that best describe the observed output. Structure computation as a tool fo r black-box modeling may be of critical importance for the development of robust, parsimonious models for the flight-test community. The ob jectives of this study are to demonstrate via analysis of Quiet Spike(TradeMark) aeroservoelastic flight-test data for several flight conditions that: linear models are inefficient for modelling aeroservoelast ic data, nonlinear identification provides a parsimonious model description whilst providing a high percent fit for cross-validated data an d the model structure and parameters vary as the flight condition is altered.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  14. Effects of Ageing and Hearing Thresholds on Speech Perception in Quiet and in Noise Perceived in Different Locations

    PubMed Central

    Wahat, Nor Haniza Abdul; Mazlan, Rafidah

    2014-01-01

    Background and Objectives This study investigated the effect of ageing on speech perception in quiet and in noise, with noise directed from front, right and left. Subjects and Methods Sixty Malay native adults with normal or near normal hearing comprising of 20 young adults (21 to 39 years old), 20 middle aged (40 to 59 years old) and 20 older adults (60 to 74 years old) participated in this study. Their speech perception ability was measured using the Malay Hearing in Noise Test (HINT) in four test conditions; 1) in quiet (HINT Q), 2) with noise from front (HINT NF), 3) with noise from right (HINT NR), and 4) with noise from left (HINT NL). Reception thresholds for sentences (RTSs) were measured in each of the aforementioned conditions using an adaptive method. Results The results showed that, 1) genuine age-related decline was found in speech perception performance in HINT (NF), 2) hearing threshold was a major determinant differentiating speech perception performance for HINT (Q) and HINT (NL) conditions, and 3) speech perception performance for HINT (NR) was determined by both age and hearing threshold. Conclusions This study suggests that, in older adults, while hearing thresholds affect speech perception in quiet, other factors such as central auditory processing and cognitive functions might be more important determinant factors for speech perception performance in noise. PMID:25558404

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  16. Cosmic rays, geomagnetic field and climate changes

    NASA Astrophysics Data System (ADS)

    Shea, M.; Smart, D.

    The possibility of a connection between cosmic radiation and climate has intrigued scientists for the past several decades. The recent studies of Friis -Christensen and Svensmark has shown an observed variation of 3-4% of the global cloud cover between 1980 and 1995 that appeared to be directly correlated with the change in galactic cosmic radiation flux over the solar cycle. However, in studies of this type, not only the solar cycle modulation of cosmic radiation must be considered, but also the changes in the cosmic radiation impinging at the top of the atmosphere as a result of the long term evolution of the geomagnetic field. We present preliminary results of an on-going study of geomagnetic cutoff rigidities over a 400-year interval. These results show (1) the change in cutoff rigidity is sufficient large so that the change in cosmic radiation flux impacting the earth is approximately equal to the relative change in flux over a solar cycle, and (2) the changes in cutoff rigidity are non- uniform over the globe with both significant increases and decreases at mid-latitude locations.

  17. Forecasts of solar and geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Joselyn, Joann

    1987-01-01

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

  18. Geomagnetic excursions reflect an aborted polarity state

    NASA Astrophysics Data System (ADS)

    Valet, Jean-Pierre; Plenier, Guillaume; Herrero-Bervera, E.

    2008-10-01

    Geomagnetic excursions represent short episodes of a few thousand years at most during which the field considerably exceeds its normal range of variability during a polarity state. Paleomagnetic records have now been obtained with extremely high temporal resolution which have improved our knowledge of these short events. We have compiled the most detailed records of excursions that had occurred during the Brunhes and Matuyama chrons. We show that virtual geomagnetic poles (VGPs) of at least one record of each event are able to reach the opposite polarity. In the next step, we have computed different simulations of excursions during which the dipole progressively vanishes before growing back without reversing. This scenario produces very few reversed directions which are only visible at some latitudes. We infer that it is impossible to reach the ratio of reversed to intermediate VGPs present in the paleomagnetic records if the excursions were not associated with a short period of reversed dipole field. Therefore, excursions should be regarded as two successive reversals bracketing an aborted polarity interval. We propose that the same underlying mechanisms prevail in both situations (excursions or reversals) and that below a certain strength the field reaches an unstable position which preludes either the achievement of a reversal or its return to the former polarity.

  19. Solar Wind Charge Exchange During Geomagnetic Storms

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  20. SOHO reveals violent action on the quiet Sun

    NASA Astrophysics Data System (ADS)

    1996-05-01

    rhythmic variations in the intensity of light or in its wavelength. The oscillations are caused by sound waves reverberating through the Sun. Just as seismology reveals the Earth's interior by studying earthquake waves, so helioseismology looks behind the Sun's enigmatic face. The helioseismologists of SOHO are delighted by their early results. They expected to benefit from a steady platform in space, where they can observe the Sun without interruption by clouds or sunsets, but what has gratified them is the clarity of the signals. Background noise previously blamed on the Sun turns out to have been due to the Earth's atmosphere. As a result SOHO gains a further advantage over ground-based stations. SOHO's oscillations imager MDI observes a million points on the Sun's visible surface once a minute. It can detect subtle, short-range oscillations due to sound waves penetrating only a short distance into the Sun. And it has generated the first chart of horizontal motions of gases just below the visible surface. "What pleases us is that shallow flows can be observed," says Philip Scherrer of Stanford University, California, who is principal investigator for MDI. "Ground-based instruments have detected motions deep inside the Sun. With SOHO we can do that too, but now we also provide the missing link to motions at the visible surface. Soon we shall make the first movies of the Sun's interior. And by relating what we see there to our measurements of surface magnetic fields we may begin to solve the mystery of why dark sunspots occur, and why they become most numerous every eleven years or so." Towards the solar maximum Observations at the present quiet phase of the solar cycle, when sunspots are scarce, provide an excellent baseline for later investigation of stormier and more confused conditions. These will occur around the year 2000 as the Sun enters its phase of maximum activity. Then the appearance of the Sun will change in SOHO's instruments, as the magnetic field contorts

  1. Correlated electron and X ray measurements of quiet time electron precipitation - A comparative study of bremsstrahlung production and transport in the atmosphere

    NASA Astrophysics Data System (ADS)

    Gaines, E. E.; Imhof, W. L.; Francis, W. E.; Walt, M.; Rosenberg, T. J.

    1986-12-01

    Five cases of X-ray observations from balloons, coordinated with measurements of precipitating electrons, were obtained during passes of the polar-orbiting satellite P78-1 near Siple, Antarctica, the launch point of the balloons. The observations, made during a geomagnetically quiet period in late December 1980 to early January 1981, showed small enhancements of the X-ray fluxes (E greater than 25 keV) and moderate trapped electron fluxes (E greater than 68 keV) with pitch angle distributions extending into the edge of the loss cone sufficient to produce the less than about 0.5 dB of cosmic noise absorption recorded by the Siple 30-MHz riometer. Bremsstrahlung production and transport in the atmosphere were calculated using the measured electron fluxes, energy spectra, and pitch angle distributions for the source. The X-ray fluxes and spectra calculated for the balloon altitudes were in good agreement with those measured from the balloons when the total energy deposition from electrons, E greater than 10 keV, exceeded 0.002 erg/sq cm s. The observed electron fluxes show that a significant continuous electron precipitation occurs at the western edge of the South Atlantic magnetic anomaly even at times of low geomagnetic activity.

  2. Correlated electron and X ray measurements of quiet time electron precipitation: a comparative study of Bremsstrahlung production and transport in the atmosphere

    SciTech Connect

    Gaines, E.E.; Imhof, W.L.; Francis, W.E.; Walt, M.; Rosenberg, T.J.

    1986-12-01

    Five cases of X ray observations from balloons coordinated with measurements of precipitating electrons were obtained during passes of the polar-orbiting satellite P78-1 near Siple, Antarctica (L--4.1), the launch point of the balloons. The observations, made during a geomagnetically quiet period in late December 1980 to early January 1981, showed small enhancements of the X ray fluxes (E>25 keV) and moderate trapped electron fluxes (E>68 keV) with pitch angle distributions extending into the edge of the loss cone sufficient to produce the approx. <0.5 dB of cosmic noise absorption recorded by the Siple 30-MHz riometer. Bremsstrahlung production and transport in the atmosphere were calculated using the measured electron fluxes, energy spectra, and pitch angle distributions for the source. The X ray fluxes and spectra calculated for the balloon altitudes were in good agreement with those measured from the balloons when the total energy deposition from electrons, E>10 keV, exceeded 2 x 10/sup -3/ erg/cm/sup 2/ s. The observed electron fluxes show that a significant continuous electron precipitation occurs at the western edge of the South Atlantic magnetic anomaly even at times of low geomagnetic activity.

  3. Effect of Energetic Electrons on Quiet Auroral Arc Formation

    NASA Astrophysics Data System (ADS)

    Hasegawa, Hiroki; Ohno, Nobuaki; Sato, Tetsuya

    2010-11-01

    The theory of feedback instability between the magnetosphere and ionosphere is believed as one of the candidate to explain the formation of quiet auroral arc. Then, some magneto-hydro- dynamics simulations showed the arc formation by this macroscopic instability, while the effect of auroral energetic electrons on the arc formation was neglected or given as a macroscopic parameter in these simulations. On the other hand, because of the recent development of particle simulations, auroral energetic electrons are thought to be produced by the super ion-acoustic double layer that should be created by microscopic instability. To make close investigation of auroral arc formation, it is necessary to consider the interaction with microscopic instability. In this paper, we numerically study the effect of energetic electrons on quiet auroral arc formation by means of the Macro-Micro Interlocked simulation.

  4. Quantitative Global Heat Transfer in a Mach-6 Quiet Tunnel

    NASA Technical Reports Server (NTRS)

    Sullivan, John P.; Schneider, Steven P.; Liu, Tianshu; Rubal, Justin; Ward, Chris; Dussling, Joseph; Rice, Cody; Foley, Ryan; Cai, Zeimin; Wang, Bo; Woodiga, Sudesh

    2012-01-01

    This project developed quantitative methods for obtaining heat transfer from temperature sensitive paint (TSP) measurements in the Mach-6 quiet tunnel at Purdue, which is a Ludwieg tube with a downstream valve, moderately-short flow duration and low levels of heat transfer. Previous difficulties with inferring heat transfer from TSP in the Mach-6 quiet tunnel were traced to (1) the large transient heat transfer that occurs during the unusually long tunnel startup and shutdown, (2) the non-uniform thickness of the insulating coating, (3) inconsistencies and imperfections in the painting process and (4) the low levels of heat transfer observed on slender models at typical stagnation temperatures near 430K. Repeated measurements were conducted on 7 degree-half-angle sharp circular cones at zero angle of attack in order to evaluate the techniques, isolate the problems and identify solutions. An attempt at developing a two-color TSP method is also summarized.

  5. The influence of "quiet time" for patients in critical care.

    PubMed

    Maidl, Carolyn A; Leske, Jane S; Garcia, Annette E

    2014-10-01

    The primary aim was to examine the influence of "quiet time" in critical care. A dual-unit, nonrandomized, uncontrolled trial of a quiet time (QT) protocol was completed. A sample of adult patients from the Neurosciences Intensive Care Unit (NICU) and Cardiovascular Intensive Care Unit (CVICU) participated. Environmental stressors were reduced and patient rest promoted prior to QT. One hundred twenty-nine patients participated in 205 QTs. A one-way, repeated measure analysis of covariance (ANCOVA) was calculated comparing Richards-Campbell Sleep Questionnaire scores, pain and anxiety over three consecutive QTs. No significant statistical effect was found. However, patients rated sleep higher and anxiety levels decreased over consecutive QTs. Ninety-three percent of patients reported QT mattered to them. The combined efforts of nursing, medicine, and ancillary staff are necessary to foster periods of uninterrupted rest, thereby optimizing patient care. Further research is needed to determine if successive QTs positively influence patient outcomes. PMID:23847172

  6. STATISTICAL ANALYSIS OF THE VERY QUIET SUN MAGNETISM

    SciTech Connect

    Martinez Gonzalez, M. J.; Manso Sainz, R.; Asensio Ramos, A.

    2010-03-10

    The behavior of the observed polarization amplitudes with spatial resolution is a strong constraint on the nature and organization of solar magnetic fields below the resolution limit. We study the polarization of the very quiet Sun at different spatial resolutions using ground- and space-based observations. It is shown that 80% of the observed polarization signals do not change with spatial resolution, suggesting that, observationally, the very quiet Sun magnetism remains the same despite the high spatial resolution of space-based observations. Our analysis also reveals a cascade of spatial scales for the magnetic field within the resolution element. It is manifest that the Zeeman effect is sensitive to the microturbulent field usually associated with Hanle diagnostics. This demonstrates that Zeeman and Hanle studies show complementary perspectives of the same magnetism.

  7. Radio Quiet Protection at the Australian Square Kilometre array site

    NASA Astrophysics Data System (ADS)

    Harvey-Smith, Lisa

    2015-08-01

    Radio astronomy relies on the detection of very faint signals from the universe. Many radio telescopes are now detrimentally affected by radio frequency interference (RFI), which results from a wide range of active spectrum users such as communications, aviation and satellites. This is why many new radio observatories are being sited at increasingly remote locations.The site for the Square Kilometre Array and its pathfinders in Australia is the Murchison Radio-Astronomy Observatory (MRO). The MRO is located more than 350km from the nearest population centre and has a large radio-quiet zone that is managed under a range of legislative agreements.In this talk I will describe the radio quiet zone, what protection it gives, how it works and how astronomers interact with the spectrum management authorities.

  8. Cosmic ray measurements on board Helios 1 from December 1974 to September 1975 Quiet time spectra, radial gradients, and solar events

    NASA Technical Reports Server (NTRS)

    Kunow, H.; Witte, M.; Wibberenz, G.; Hempe, H.; Mueller-Mellin, R.; Green, G.; Iwers, B.; Fuckner, J.

    1977-01-01

    The considered time period is characterized by a general decrease in solar activity towards a minimum which occurred in July 1976. The relatively quiet solar conditions facilitate the separation of the gradually varying galactic cosmic radiation from superimposed events of different characteristics. The inspection of neutron monitor data shows that the period is characterized by a slow increase of the high energy galactic cosmic radiation at a relatively constant rate. Attention is given to the instrumentation employed, intensity time profiles and preliminary radial gradients, and quiet time energy spectra. The solar particle events discussed include the January 5, 1976 event, the March 3, 1975 event, and the March 19/20, 1975 event.

  9. Dark Skies are a Universal Resource. So are Quiet Skies!

    NASA Astrophysics Data System (ADS)

    Maddalena, Ronald J.; Heatherly, S.

    2008-05-01

    You've just purchased your first telescope. But where to set it up? Certainly not a WalMart parking lot. Too much light pollution! In the same way that man-made light obscures our night sky and blinds ground-based optical telescopes, man-made radio signals blind radio telescopes as well. NRAO developed the Quiet Skies project to increase awareness of radio frequency interference (RFI) and radio astronomy in general by engaging students in local studies of RFI. To do that we created a sensitive detector which measures RFI. We produced 20 of these, and assembled kits containing detectors and supplementary materials for loan to schools. Students conduct experiments to measure the properties of RFI in their area, and input their measurements into a web-based data base. The Quiet Skies project is a perfect complement to the IYA Dark Skies Awareness initiative. We hope to place 500 Quiet Skies detectors into the field through outreach to museums and schools around the world. Should we be successful, we will sustain this global initiative via a continuing loan program. One day we hope to have a publicly generated image of the Earth which shows RFI much as the Earth at Night image illustrates light pollution. The poster will present the components of the project in detail, including our plans for IYA, and various low-cost alternative strategies for introducing RFI and radio astronomy to the public. We will share the results of some of the experiments already being performed by high school students. Development of the Quiet Skies project was funded by a NASA IDEAS grant. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  10. Quiet Clean General Aviation Turbofan (QCGAT) technology study, volume 1

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The preliminary design of an engine which satisfies the requirements of a quiet, clean, general aviation turbofan (QCGAT) engine is described. Also an experimental program to demonstrate performance is suggested. The T700 QCGAT engine preliminary design indicates that it will radiate noise at the same level as an aircraft without engine noise, have exhaust emissions within the EPA 1981 Standards, have lower fuel consumption than is available in comparable size engines, and have sufficient life for five years between overhauls.

  11. Monitoring Radio Frequency Interference: The Quiet Skies Project

    NASA Astrophysics Data System (ADS)

    Rapp, S.; Gear, C.; Maddalena, R. J.; Heatherly, S. A.

    2004-12-01

    The Quiet Skies Project is a result of the Research Experience for Teacher (RET) program during the summer of 2004. Teachers were involved in discovering the relationship between radio frequency interference (RFI) and radio astronomy observations. S. Rapp participated in astronomy observations with the Green Bank Telescope in order to characterize RFI issues at radio observatories and worked closely with the Green Bank Interference Protection Group. This work included such tasks as mitigation of locally-generated RFI from power poles and running radiation propagation studies for transmitters within the National Radio Quiet Zone. A curriculum was created to allow high school students to participate in a research effort to determine RFI levels in their communities. The aim of the project is to promote student awareness of radio astronomy and radio frequency interference through an inquiry-based science curriculum. It is hoped that the project will go national by 2007. A prototype RFI detector was created and tested at four wavelengths; 850, 900, 1425, and 1675 MHz. High school students used a beta version of the RFI detector to explore the occurrence of RFI at their schools and in their communities. The student goals of the Quiet Skies Project are to: Measure interference levels at their schools and in their communities; Reduce and transmit their data to an NRAO data base; Use online spectrum allocation data, and local information to determine possible causes of interference in their area; Analyze the complex trade-offs between radio astronomy's need for quiet skies, and other commercial, and non-commercial uses of the spectrum and share their insights with others. This work was funded by the NSF-RET program and a grant from the NASA-IDEAS program

  12. PERVASIVE LINEAR POLARIZATION SIGNALS IN THE QUIET SUN

    SciTech Connect

    Bellot Rubio, L. R.; Orozco Suarez, D.

    2012-09-20

    This paper investigates the distribution of linear polarization signals in the quiet-Sun internetwork using ultra-deep spectropolarimetric data. We reduce the noise of the observations as much as is feasible by adding single-slit measurements of the Zeeman-sensitive Fe I 630 nm lines taken by the Hinode spectropolarimeter. The integrated Stokes spectra are employed to determine the fraction of the field of view covered by linear polarization signals. We find that up to 69% of the quiet solar surface at disk center shows Stokes Q or U profiles with amplitudes larger than 0.032% (4.5 times the noise level of 7 Multiplication-Sign 10{sup -5} reached by the longer integrations). The mere presence of linear polarization in most of the quiet Sun implies that the weak internetwork fields must be highly inclined, but we quantify this by inverting those pixels with Stokes Q or U signals well above the noise. This allows for a precise determination of the field inclination, field strength, and field azimuth because the information carried by all four Stokes spectra is used simultaneously. The inversion is performed for 53% of the observed field of view at a noise level of 1.3 Multiplication-Sign 10{sup -4} I{sub c}. The derived magnetic distributions are thus representative of more than half of the quiet-Sun internetwork. Our results confirm the conclusions drawn from previous analyses using mainly Stokes I and V: internetwork fields are very inclined, but except in azimuth they do not seem to be isotropically distributed.

  13. Can Quiet Standing Posture Predict Compensatory Postural Adjustment?

    PubMed Central

    Moya, Gabriel Bueno Lahóz; Siqueira, Cássio Marinho; Caffaro, Renê Rogieri; Fu, Carolina; Tanaka, Clarice

    2009-01-01

    OBJECTIVE The aim of this study was to analyze whether quiet standing posture is related to compensatory postural adjustment. INTRODUCTION The latest data in clinical practice suggests that static posture may play a significant role in musculoskeletal function, even in dynamic activities. However, no evidence exists regarding whether static posture during quiet standing is related to postural adjustment. METHODS Twenty healthy participants standing on a movable surface underwent unexpected, standardized backward and forward postural perturbations while kinematic data were acquired; ankle, knee, pelvis and trunk positions were then calculated. An initial and a final video frame representing quiet standing posture and the end of the postural perturbation were selected in such a way that postural adjustments had occurred between these frames. The positions of the body segments were calculated in these initial and final frames, together with the displacement of body segments during postural adjustments between the initial and final frames. The relationship between the positions of body segments in the initial and final frames and their displacements over this time period was analyzed using multiple regressions with a significance level of p ≤ 0.05. RESULTS We failed to identify a relationship between the position of the body segments in the initial and final frames and the associated displacement of the body segments. DISCUSSION The motion pattern during compensatory postural adjustment is not related to quiet standing posture or to the final posture of compensatory postural adjustment. This fact should be considered when treating balance disturbances and musculoskeletal abnormalities. CONCLUSION Static posture cannot predict how body segments will behave during compensatory postural adjustment. PMID:19690665

  14. The F region and topside ionosphere response to a strong geomagnetic storm at Arecibo

    NASA Astrophysics Data System (ADS)

    Gong, Yun; Zhou, Qihou; Zhang, Shao Dong; Aponte, NéStor; Sulzer, Michael; GonzáLez, Sixto A.

    2013-08-01

    analyze the data derived from the Arecibo incoherent scatter radar measurements to investigate the response of the F region and topside ionosphere to a strong geomagnetic storm that occurred during the period of 5-6 August 2011. The meridional wind was extremely enhanced at the early stage of the storm. The peak velocity reached approximately 300 m/s at an altitude of 340 km, which is seldom seen at the Arecibo latitude. During the storm, the vertical ion drift caused by the meridional wind was positively correlated with that caused by the electric field, which is opposite to the quiet time relationship. The disturbed vertical ion drifts resulted in large ionospheric perturbations in the F and topside regions. Several collapses were observed in hmF2 during the storm night. NmF2 rapidly increased after the storm and then decreased around midnight. At an altitude of 610 km, the concentration of H+ and O+, and the ratio of H+ over electron density all exhibited large variations. The ratio of H+ over electron density changed from less than 10% to more than 80% in a matter of 2 hours in the morning of 6 August. One explanation for such a behavior is that vertical transport dominates over charge exchange late at night due to the lower concentration of O+.

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

    NASA Astrophysics Data System (ADS)

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

    1993-03-01

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

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

    PubMed

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

    1993-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Temerin, Michael; Li, Xinlin

    2015-07-01

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

  18. Geomagnetic influence on aircraft radiation exposure during a solar energetic particle event in October 2003

    NASA Astrophysics Data System (ADS)

    Mertens, Christopher J.; Kress, Brian T.; Wiltberger, Michael; Blattnig, Steve R.; Slaba, Tony S.; Solomon, Stanley C.; Engel, M.

    2010-03-01

    We present initial results from the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model during the Halloween 2003 superstorm. The objective of NAIRAS is to produce global, real-time, data-driven predictions of ionizing radiation for archiving and assessing the biologically harmful radiation exposure levels at commercial airline altitudes. We have conducted a case study of radiation exposure during a high-energy solar energetic particle (SEP) event in October 2003. The purpose of the case study is to quantify the important influences of the storm time and quiet time magnetospheric magnetic field on high-latitude SEP atmospheric radiation exposure. The Halloween 2003 superstorm is an ideal event to study magnetospheric influences on atmospheric radiation exposure since this event was accompanied by a major magnetic storm which was one of the largest of solar cycle 23. We find that neglecting geomagnetic storm effects during SEP events can underestimate the high-latitude radiation exposure from nearly 15% to over a factor of 2, depending on the flight path relative to the magnetosphere open-closed boundary.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. First results on quiet and magnetic granulation from SOUP

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Tarbell, T. D.; Acton, L.; Duncan, D.; Ferguson, S. H.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.; Morrill, M.

    1987-01-01

    The flight of Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 allowed the collection of time sequences of diffraction limited (0.5 arc sec) granulation images with excellent pointing (0.003 arc sec) and completely free of the distortion that plagues groundbased images. The p-mode oscillations are clearly seen in the data. Using Fourier transforms in the temporal and spatial domain, it was shown that the p-modes dominate the autocorrelation lifetime in magnetic regions. When these oscillations are removed the autocorrelation lifetime is found to be 500 sec in quiet and 950 sec in magnetic regions. In quiet areas exploding granules are seen to be common. It is speculated that a significant fraction of granule lifetimes are terminated by nearby explosions. Using local correlation tracking techniques it was able to measure horizontal displacements, and thus transverse velocities, in the magnetic field. In quiet sun it is possible to detect both super and mesogranulation. Horizontal velocities are as great as 1000 m/s and the average velocity is 400 m/s. In magnetic regions horizontal velocities are much less, about 100 m/s.

  1. Evidence for wave heating of the quiet-sun corona

    SciTech Connect

    Hahn, M.; Savin, D. W.

    2014-11-10

    We have measured the energy and dissipation of Alfvénic waves in the quiet Sun. A magnetic field model was used to infer the location and orientation of the magnetic field lines along which the waves are expected to travel. The waves were measured using spectral lines to infer the wave amplitude. The waves cause a non-thermal broadening of the spectral lines, which can be expressed as a non-thermal velocity v {sub nt}. By combining the spectroscopic measurements with this magnetic field model, we were able to trace the variation of v {sub nt} along the magnetic field. At each footpoint of the quiet-Sun loops, we find that waves inject an energy flux in the range of 1.3-5.5 × 10{sup 5} erg cm{sup –2} s{sup –1}. At the minimum of this range, this amounts to more than 80% of the energy needed to heat the quiet Sun. We also find that these waves are dissipated over a region centered on the top of the loops. The position along the loop where the damping begins is strongly correlated with the length of the loop, implying that the damping mechanism depends on the global loop properties rather than on local collisional dissipation.

  2. Geomagnetic jerks as chaotic fluctuations of the Earth's magnetic field

    NASA Astrophysics Data System (ADS)

    Qamili, E.; de Santis, A.; Isac, A.; Mandea, M.; Duka, B.; Simonyan, A.

    2013-04-01

    The geomagnetic field is chaotic and can be characterized by a mean exponential time scale < τ > after which it is no longer predictable. It is also ergodic, so time analyses can substitute the more difficult phase space analyses. Taking advantage of these two properties of the Earth's magnetic field, a scheme of processing global geomagnetic models in time is presented, to estimate fluctuations of the time scale τ. Here considering that the capability to predict the geomagnetic field is reduced over periods of geomagnetic jerks, we propose a method to detect these events over a long time span. This approach considers that epochs characterized by relative minima of fluctuations in time scale τ, i.e., those periods when a geomagnetic field is less predictable, are possible jerk occurrence dates. We analyze the last 400 years of the geomagnetic field (covered by the Gufm1 model) to detect minima of fluctuations, i.e., epochs characterized by low values of the time scale. Most of the well known jerks are confirmed through this method and a few others have been suggested. Finally, we also identify some short periods when the field is less chaotic (more predictable) than usual, naming these periods as steady state geomagnetic regime, to underline their opposite behavior with respect to jerks.

  3. Is motivation influenced by geomagnetic activity?

    PubMed

    Starbuck, S; Cornélissen, G; Halberg, F

    2002-01-01

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

  4. Head stability during quiet sitting in children with cerebral palsy: effect of vision and trunk support

    PubMed Central

    Saavedra, Sandra; Woollacott, Marjorie; van Donkelaar, Paul

    2010-01-01

    Deficits in postural control are one of the hallmarks of disability in children with cerebral palsy. Yet, much remains unknown regarding the etiology of postural deficits in these children. Here we evaluated postural control at a simplified task level by measuring head stability during quiet sitting while systematically manipulating the level of trunk support and vision in 15 children with CP (6–16 years), 26 typically developing (TD) children (4–14 years), and 11 adults. While TD children did not differ significantly from adults, children with CP had greater head movement than adults in both the sagittal and frontal planes under all conditions except frontal plane movement with Torso Support. Vision did not affect head stability in the sagittal plane for any group while it had differential effects on head stability in the frontal plane. Lack of vision improved head stability in adults and older TD children while destabilizing the head in young children (TD and CP) during the most unstable sitting position. Moreover, vision affected children with CP differently depending on their movement disorder. Children with spastic CP performed worse with eyes closed while those with dyskinetic CP had improved head stability with eyes closed. Our results demonstrate that children with mild to moderate CP have deficits in head stability even during quiet sitting. PMID:19756550

  5. Tracking pigeons in a magnetic anomaly and in magnetically "quiet" terrain

    NASA Astrophysics Data System (ADS)

    Schiffner, Ingo; Fuhrmann, Patrick; Wiltschko, Roswitha

    2011-07-01

    Pigeons were released at two sites of equal distance from the loft, one within a magnetic anomaly, the other in magnetically quiet terrain, and their tracks were recorded with the help of GPS receivers. A comparison of the beginning of the tracks revealed striking differences: within the anomaly, the initial phase lasted longer, and the distance flown was longer, with the pigeons' headings considerably farther from the home direction. During the following departure phase, the birds were well homeward oriented at the magnetically quiet site, whereas they continued to be disoriented within the anomaly. Comparing the tracks in the anomaly with the underlying magnetic contours shows considerable differences between individuals, without a common pattern emerging. The differences in magnetic intensity along the pigeons' path do not differ from a random distribution of intensity differences around the release site, indicating that the magnetic contours do not directly affect the pigeons' routes. Within the anomaly, pigeons take longer until their flights are oriented, but 5 km from the release point, the birds, still within the anomaly, are also significantly oriented in the home direction. These findings support the assumption that magnetically anomalous conditions initially interfere with the pigeons' navigational processes, with birds showing rather individual responses in their attempts to overcome these problems.

  6. Stability and Control Analysis of the F-15B Quiet SpikeTM Aircraft

    NASA Technical Reports Server (NTRS)

    McWherter, Shaun C.; Moua, Cheng M.; Gera, Joseph; Cox, Timothy H.

    2009-01-01

    The primary purpose of the Quiet Spike(TradeMark) flight research program was to analyze the aerodynamic, structural, and mechanical proof-of-concept of a large multi-stage telescoping nose spike installed on the National Aeronautics and Space Administration Dryden Flight Research Center (Edwards, California) F-15B airplane. This report describes the preflight stability and control analysis performed to assess the effect of the spike on the stability, controllability, and handling qualities of the airplane; and to develop an envelope expansion approach to maintain safety of flight. The overall flight test objective was to collect flight data to validate the spike structural dynamics and loads model up to Mach 1.8. Other objectives included validating the mechanical feasibility of a morphing fuselage at operational conditions and determining the near-field shock wave characterization. The two main issues relevant to the stability and control objectives were the effects of the spike-influenced aerodynamics on the F-15B airplane flight dynamics, and the air data and angle-of-attack sensors. The analysis covered the sensitivity of the stability margins, and the handling qualities due to aerodynamic variation and the maneuvering limitations of the F-15B Quiet Spike configuration. The results of the analysis and the implications for the flight test program are also presented.

  7. Nature of the Jurassic Magnetic Quiet Zone revealed by the sea-surface, mid-water, and near-source magnetic sensor data in the western Pacific.

    NASA Astrophysics Data System (ADS)

    Tominaga, M.; Tivey, M.; Sager, W. W.

    2015-12-01

    The nature of the Jurassic Quiet Zone (JQZ) has been a long-standing debate in understanding Earth's geomagnetic field history and behavior. We present a coherent and likely globally significant marine magnetic reversal record for the JQZ by constructing a correlation of new and previously acquired magnetic anomaly profiles in the western Pacific. We obtained a high-resolution marine magnetic anomaly record using sea surface, mid-water (3-km level deep-towed), and near-bottom (Autonomous Underwater Vehicle (AUV)) profiles that targeted a spreading corridor in the Hawaiian lineation in 2011 (TN272 on R/V Thompson) and 2014 (SKQ2014S2 on R/V Sikuliaq). To extract crustal magnetic signals, the sea surface and mid-water magnetic data were corrected for ship-to-sensor offset, the diurnal effect, and the present-day ambient geomagnetic field. Mid-water data were upward continued to a constant 3 km level plane and to the sea surface. Near-bottom data were calibrated to remove the induced magnetic field by AUV Sentry, then corrected for IGRF and diurnal variations. We used these near-source data as an anchor for correlations with the sea surface and mid-water level data because of the AUV's superb inertial navigation and hydrodynamically stable, quiet platform environment. Our sea surface anomaly correlation with the previously established Japanese lineation sequence shows (i) an excellent correlation of anomaly shapes from M29 to M42; (ii) a remarkable similarity in anomaly amplitude envelope, which decreases back in time from M19 to M38, with a minimum at M41, then increases back in time from M42; and (iii) refined locations of pre-M25 lineations in the Hawaiian lineation set. Moreover, short-wavelength anomalies from the mid-water and near-bottom profiles show a strong similarity in the M37/M38 polarity attributes found both in the magnetostratigraphic and marine magnetic records, implying that rapid magnetic reversals were occurring at that time. The average reversal

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

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

  9. Geomagnetic storms: Potential economic impacts on electric utilities

    SciTech Connect

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

    1991-03-20

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

  10. Solar wind turbulence as a driver of geomagnetic activity

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  11. Search for correlation between geomagnetic disturbances and mortality

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Donmez, Burcin; Kilcik, Ali

    2016-07-01

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

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

    NASA Technical Reports Server (NTRS)

    Forbes, Kevin F.; Cyr, Chris St

    2012-01-01

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

  14. Geomagnetic Effect Caused by 1908 Tunguska Event

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    The analysis of the magnetograms of Irkutsk observatory on the 30th June 1908 showed that the explosion of Tunguska bolide was accompanied by variations of the Earth’s magnetic field, which were being continued for several hours [1]. Irkutsk geophysical observatory is located approximately in 950 km to the southeast from the point of Tunguska explosion and it was nearest point, where the continuous recording of the components of the geomagnetic field was in progress. We suppose that it was caused by magnetic field of the current system, generated in the E-layer of ionosphere by gas dynamical flow after the Tunguska explosion [2]. Plunging through the atmosphere, cosmic body forms a hot rarefied channel behind it; the hydrostatic equilibrium of pressure in the channel becomes broken. The particles of the body vapor and atmospheric air, involved in the motion, lift along this channel upward (so-called plume). In the rarefied layers of the atmosphere they move along the ballistic trajectories in the gravitational field. While falling down gas loses its kinetic energy in dense layers of the atmosphere, which is converted into thermal energy. Then the reflected shock wave is formed. The gas heated in it rises up and all these processes repeat. The effects of heating and ionization of gas at height of 100 km, caused by the oscillations in the atmosphere, can lead to a distortion of the existing current system in ionosphere and generation of new ones. Since the Tunguska body had an oblique trajectory, the plume was ejected in the direction opposite to motion of Tunguska body and provided ionized region at the distance about 700 km from the epicenter at time moment 400 seconds after explosion. Gas dynamical simulation and estimates of the plume parameters have been fulfilled to calculate conductivity profiles and the electric field. Magnetic field of the induced current system has been obtained by the numerical simulation of Maxwell’s equations. Analysis of calculation

  15. Solar activity geomagnetic field and terrestrial weather

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  16. Protection against lightning at a geomagnetic observatory

    NASA Astrophysics Data System (ADS)

    Čop, R.; Milev, G.; Deželjin, D.; Kosmač, J.

    2014-08-01

    The Sinji Vrh Geomagnetic Observatory was built on the brow of Gora, the mountain above Ajdovščina, which is a part of Trnovo plateau, and all over Europe one can hardly find an area which is more often struck by lightning than this southwestern part of Slovenia. When the humid air masses of a storm front hit the edge of Gora, they rise up more than 1000 m in a very short time, and this causes an additional electrical charge of stormy clouds. The reliability of operations performed in every section of the observatory could be increased by understanding the formation of lightning in a thunderstorm cloud and the application of already-proven methods of protection against a stroke of lightning and against its secondary effects. To reach this goal the following groups of experts have to cooperate: experts in the field of protection against lightning, constructors and manufacturers of equipment and observatory managers.

  17. Geomagnetism and paleomagnetism 1979-1983

    NASA Astrophysics Data System (ADS)

    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.

  18. Forecasting geomagnetic activities from the Boyle Index

    NASA Astrophysics Data System (ADS)

    Bala, R.; Reiff, P. H.

    2010-12-01

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

  19. Historical records of the geomagnetic field

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  20. Homogenization of the historical records of geomagnetic field components and geomagnetic K-index of the Magnetic Observatory of Coimbra

    NASA Astrophysics Data System (ADS)

    Morozova, Anna; Ribeiro, Paulo; Pais, M. Alexandra

    2013-04-01

    The Coimbra Magnetic Observatory (COI) (Portugal) has a long history of observation of the geomagnetic field, spanning almost 150 years. Measurements of the geomagnetic field components started in 1866 and include the observations of all components: horizontal (H), downward vertical (Z), northward (X), eastward (Y), total field magnitude (F), inclination (I) and declination (D). These long instrumental geomagnetic records provide very important information about variability of measured parameters, their trends and cycles, and can be used to improve our knowledge on the sources that drive variations of the geomagnetic field: liquid core dynamics (internal) and solar forcing (external). However, during the long life of the Coimbra observatory, some inevitable changes in station location, instrument's park and electromagnetic environment took place. These changes affected the quality of the data causing breaks and jumps in the series. Clearly, these inhomogeneities, typically of shift-like (step-like) or trend-like, have to be corrected or, at least, minimized in order for the data to be used in scientific studies or to be submitted to international databases. The homogenization of the monthly and annual averages of geomagnetic field components has been done using visual and statistical tests (e.g. standard normal homogeneity test), allowing to estimate not only the level of inhomogeneity of the studied series, but also to detect the highly probable homogeneity break points. These have been compared with the metadata, reference series from the nearest geomagnetic stations and geomagnetic field models (e.g. CM4 and CHAOS3) in order to find and to set up the indispensable correction factors. Similar methods have been applied to the homogenization of the local geomagnetic K-index series (from 1952 to 2012). As a result, the homogenized geomagnetic monthly and annual averages of the series measured in COI are considered to be essentially free of artificial shifts and

  1. Asymmetry of geomagnetic field horizontal components variation connected to field aligned currents appeared at early recovery phase in region of plasmospheric bulges

    NASA Astrophysics Data System (ADS)

    Barkhatova, Oksana; Barkhatov, Nikolay; Bespalov, Peter

    2010-05-01

    Studying of ring current dynamics at different phases of geomagnetic storm development assumes consideration of questions connected with its asymmetric part closing. Such closing of asymmetric ring current on ionosphere can be provided with existence of intensive field aligned currents. These currents can arise due to interaction of ring current energetic ions with plasmospheric bulges in day time and evening sectors of magnetosphere. At the same time in regions of plasmospheric bulges develop cyclotron instability. Interaction of ring current energetic ions with cyclotron waves leads to them isotropisation and precipitation in loss-cone therefore intensive field aligned currents are formed. In this work the experimental basis of asymmetric part of geomagnetic field disturbance connection with presence of plasmospheric bulges at early recovery phase of geomagnetic storm is received. Spectrums of geomagnetic field horizontal component on two meridional chains of ground based stations which correspond to location of day time and evening plasmospheric bulges are investigated. Research was carried out for two cases - when the stations chain is in region of plasmospheric bulge and when it is outside of its boundaries. As a result in spectrums of geomagnetic field horizontal component variations at ground magnetic stations the increase of spectral components amplitudes in geomagnetic pulsations range is observed. It is marked at an entrance of stations in regions corresponding to projections of day time and evening plasmospheric bulges. Comparison of geomagnetic field horizontal component variations at the stations which are taking place in region of a day time bulge is carried out. It is founded, that at an entrance of stations in this bulge region, evident depression of horizontal components values is observed. At stations which are located outside a bulge, this depression is less significant. In quiet days, when streams of ring current energetic ions are absent, the

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

    NASA Astrophysics Data System (ADS)

    Olabode, Ayomide; Ariyibi, Emmanuel

    2016-07-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

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

  4. A comprehensive analysis of the geomagnetic storms occurred dur

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  5. Spatial and temporal power spectra of the geomagnetic field

    SciTech Connect

    McLeod, M.G.

    1996-02-10

    This report explores the statistical properties of the geomagnetic field. This research tries to determine the gaussian coefficient covariance from magnetic field measurements of spatial and temporal power spectra and give a theoretical explanation for the nature of these covariances.

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

    USGS Publications Warehouse

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

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Xie, L.

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Kaushik, Sonia

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  11. Inherited Magnetic Maps in Salmon and the Role of Geomagnetic Change.

    PubMed

    Putman, Nathan F

    2015-09-01

    Migration in animals has evolved as an adaptation to environmental variability across space and through time. The availability of reliable sensory cues and guidance mechanisms used in navigating among disparate locations is an essential component of this behavior. An "inherited magnetic map" is navigational solution that has evolved in some marine animals that, without prior experience or guidance from older conspecifics, migrate to oceanic foraging grounds. Laboratory experiments demonstrate that navigationally naïve salmon encountering magnetic fields characteristic of certain regions along their migratory route will bias their swimming in a particular direction. Simulations of this behavior within realistic models of oceanic circulation suggest that such behavior is highly adaptive, making the migratory route more predictable and facilitating movement into favorable oceanic regions. Such behavior is possible due to the spatial gradients of components of the geomagnetic field (e.g., the inclination angle of field lines and the total field intensity) that provide a bicoordinate grid across much of the Earth's surface. However, this environmental feature is not static, but experiences gradual and unpredictable changes that can be substantial over successive generations. Thus, drift of the geomagnetic field, in addition to variable oceanic conditions, could play a major role in shaping the distribution of marine taxa that are dependent upon such mechanisms for migratory guidance. Several possibilities are discussed for how animals might mitigate the effects of geomagnetic drift, such as calibrating their inherited magnetic map relative to the field in which they develop. Further exploration of the dynamics of the geomagnetic field in context of animal navigation is a promising avenue for understanding the how animals deal with an ever-changing environment. PMID:25888216

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  13. Coordination of the head with respect to the trunk and pelvis in the roll and pitch planes during quiet stance.

    PubMed

    Honegger, F; van Spijker, G J; Allum, J H J

    2012-06-28

    This study examined the relationship between head and trunk sway during quiet stance and compared this relationship with that of the pelvis to the trunk. Sixteen younger and 14 elderly subjects participated, performing four different sensory tasks: standing quietly on a firm or foam support surface, with eyes open or closed. Roll and pitch angular velocities were recorded with six body-worn gyroscopes; a set of two mounted at the upper trunk, an identical set at the hips, and another set on a head band. Angle correlation analysis was performed in three frequency bands: below 0.7 Hz (LP), above 3 Hz (HP) and in between (BP) using the integrated angle velocity signals. Angular velocities were spectrally analysed. Greater head than trunk motion was observed in angle correlations, power spectral density (PSD) ratios, and transfer functions (TFs). Head on trunk motion could be divided for all sensory conditions into a low-frequency (<0.7 Hz) "head locked to trunk" inverted pendulum mode, a mid-frequency (ca. 3 Hz), resonant mode, and a slightly anti-phasic head motion on stabilised trunk, high-frequency (>3 Hz) mode. There was coherent motion between head and trunk but not between head and pelvis. Trunk and pelvis data were consistent with previously reported in-phase and anti-phase movements between these segments. Significant age differences were not found. These data indicate that during quiet stance body motion increases in the order of pelvis, trunk, head and quiet stance involves control of at least two separate links: trunk on pelvis and head on trunk dominated by head resonance. The head is locked to the trunk for low-frequency motion possibly because motion is just supra-vestibular threshold. The head is not stabilised in space during stance, rather the pelvis is.

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

    PubMed

    Moore, F R

    1977-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Heirtzler, J. R.

    1999-01-01

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

  16. Moon Farside, Quiet Cone and the "RLI" Experiment

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    The Farside of the Moon is a unique place. Radio emissions coming from the Earth, and notably the from Telecommunication Satellites orbiting the Earth, don't get there since shielded by the Moon's spherical body. A radio telescope placed inside Crater Daedalus (just at the center of the Farside) would thus sense no man-made RFI (Radio Frequency Interference) and would be ideal for all radio astronomical and SETI searches. Above the Farside, a conical region extends into space, the ``Quiet Cone'', tangent to the Moon surface and with apex a few thousands of kilometers above the Moon. The size of the Quiet Cone, however, is only vaguely known, and changes in time, because the orbits of secret military satellites around the Earth are of course unknown. The only way to know the current, actual size of the Quiet Cone is to send a radiometer into orbit around the Moon and find out where the RFI coming from the Earth is actually shielded and where it is not. The RLI Experiment (RLI is an acronym for ``Radiometro Lunare Italiano'', i.e. Italian Moon Radiometer), is currently under construction by an Italian team coordinated by this author as Principal Investigator. The RLI is hopefully going to be put into orbit around the Moon before 2007. This will be done by placing the RLI radiometer aboard the ``Trailbalzer'', the first American commercial Moon spacecraft, built by TransOrbital Inc.. The RLI Experiment will take direct measurements of the intensity of man-made RFI around two frequencies: The band in between 10.7 and 11.8 GHz (main frequency band of European TV transmissions and, in part, also of American TV transmissions) and The band in between 10 Hz and 10 kHz, to get a Fourier spectrum of the very thin Moon atmosphere. A scientific and technical description of the RLI mission is given in this paper.

  17. Schizophrenia and season of birth: relationship to geomagnetic storms.

    PubMed

    Kay, Ronald W

    2004-01-01

    An excess pattern of winter and spring birth, of those later diagnosed as schizophrenic, has been clearly identified in most Northern Hemisphere samples with none or lesser variation in Equatorial or Southern Hemisphere samples. Pregnancy and birth complications, seasonal variations in light, weather, temperature, nutrition, toxins, body chemistry and gene expression have all been hypothesized as possible causes. In this study, the hypothesis was tested that seasonal variation in the geomagnetic field of the earth primarily as a result of geomagnetic storms (GMS) at crucial periods in intrauterine brain development, during months 2 to 7 of gestation could affect the later rate of development of schizophrenia. The biological plausibility of this hypothesis is also briefly reviewed. A sample of eight representative published studies of schizophrenic monthly birth variation were compared with averaged geomagnetic disturbance using two global indices (AA*) and (aa). Three samples showed a significant negative correlation to both geomagnetic indices, a further three a significant negative correlation to one of the geomagnetic indices, one showed no significant correlation to either index and one showed a significant positive correlation to one index. It is suggested that these findings are all consistent with the hypothesis and that geomagnetic disturbance or factors associated with this disturbance should be further investigated in birth seasonality studies. PMID:14693348

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

    NASA Astrophysics Data System (ADS)

    Bailey, Rachel L.; Leonhardt, Roman

    2016-06-01

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

  19. Globally strong geomagnetic field intensity circa 3000 years ago

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  20. Are migrating raptors guided by a geomagnetic compass?

    USGS Publications Warehouse

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

    2006-01-01

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