bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impacts of torus model on studies of geometrical relationships between interplanetary magnetic clouds and their solar origins
Authors: Marubashi Katsuhide , Sung Suk-Kyung , Cho Kyung-Suk , Lepping Ronald P. 
Published: August 2014

Abstract
Our recent analysis of interplanetary magnetic clouds (MCs) showed that the orientations of MC axes determined by a model fitting with curvature of MCs taken into account (referred to as a torus model, hereafter) can be significantly different from those obtained from fittings with a straight cylinder model. Motivated by this finding, we re-examined geometrical relationships between magnetic field structures of MCs and their solar origins. This paper describes the results of the re-examination with special attention paid to two MC events, for which different orientations of MC axes were obtained from a torus model and a cylinder model. For both cases, it is shown that the torus models give the MC geometries of magnetic field structures in good agreement with those of coronal arcade structures which were formed in association with the launch of MCs along the magnetic field inversion lines. Summarizing the analysis results for 12 MCs investigated here, we conclude that: (1) the formation of coronal arcade structure is a good indication of MC formation; (2) MC geometries can be obtained that are consistent with the coronal arcades with respect to the axis orientation and the magnetic field structure including chirality, indicating that no significant direction changes occurred during the propagation of MCs through the interplanetary medium.
Halo coronal mass ejections and geomagnetic storms
Authors: Gopalswamy Nat 
Published: August 2014

Abstract
In this letter, I show that the discrepancies in the geoeffectiveness of halo coronal mass ejections (CMEs) reported in the literature arise due to the varied definitions of halo CMEs used by different authors. In particular, I show that the low geoeffectiveness rate is a direct consequence of including partial halo CMEs. The geoeffectiveness of partial halo CMEs is lower because they are of low speed and likely to make a glancing impact on Earth.
Influence of the foreshock of the Earth’s bow shock on the interplanetary shock propagation during their mutual interaction
Authors: Přech Lubomír , Němeček Zdeněk , Šafránková Jana 
Published: August 2014

Abstract
Interplanetary shocks have been recognized as a very efficient source of geomagnetic disturbances. We present a short study of the propagation of one interplanetary (IP) shock observed by five spacecraft located in the solar wind far upstream of the Earth’s bow shock as well as in its close vicinity. The IP shock normal was highly inclined from the Sun-Earth line and thus the IP shock-bow shock interaction started at the flank. We have found a significant evolution of IP shock parameters during its motion along the bow shock. This modification is discussed and attributed to the presence of strong fluxes of energetic particles in the foreshock.
Seismotectonic implications of the Kyushu-Palau ridge subducting beneath the westernmost Nankai forearc
Authors: Park Jin-Oh , Hori Takane , Kaneda Yoshiyuki 
Published: August 2014

AbstractThe Kyushu-Palau ridge, a remnant arc on the Philippine Sea Plate, subducts beneath the Eurasian Plate along the westernmost part of the Nankai Trough. A seismic reflection profile on strike line images the ∼70-km-wide Kyushu-Palau ridge where it subducts beneath the toe of the forearc accretionary wedge. The geomagnetic anomaly signature, seafloor topographic features, wide-angle refraction data, and on-land geomorphologic evidence enable us to trace the forearc extension of the subducted ridge up to the east Kyushu. The subducted Kyushu-Palau ridge with excess mass may be relatively buoyant, and thus is more likely to resist subduction upon collision with the overriding plate at depth, leading us to speculate that there is locally large tectonic stress at the contact zone between the subducted ridge and base of the overriding plate. The large stress zone is marked by historic thrust-type intermediate-class (magnitude 6 or 7) earthquakes. The flank regions of the subducted buoyant Kyushu-Palau ridge are more likely to tear and result in slab fracturing when the ridge subducts deeper. We propose that the subducted Kyushu-Palau ridge may serve not only as a seismic asperity at depth but also produce the slab fracture as a seismic barrier inhibiting the rupture propagation of the adjacent megathrust earthquakes in the Hyuga segment.
Scale factor mitigating non-compliance of double-frequency altimeter measurements of the ionospheric electron content over the oceans with GPS-TEC maps
Authors: Gulyaeva T. L. , Arikan F. , Delay S. H. 
Published: August 2014

Abstract
This paper presents results from a study of GPS total electron content (TEC) grid maps and ionospheric electron content (IEC) over the oceans delivered by the TOPEX/Jason satellites during half a solar cycle (July 2001 to December 2008). The IEC data are averaged and binned at latitudes from 60°S to 60°N in steps of 5°±2.5°, at longitudes from 180°W to 180°E in steps of 15°±7.5°, and for 0–23 h UT in steps of 1±0.5 h UT. The ratio of monthly averaged TEC/IEC over the oceans from the observations was compared to the reference model ratio of TECm/IECm obtained using the plasmaspheric model augmented with the International Reference Ionosphere. By definition, TEC should exceed IEC by the plasmaspheric electron content (PEC) contribution at the altitude range from 1336 km (TOPEX orbit) to 20,200 km (GPS orbit). However, as solar activity tends to the minimum, we found that IEC estimates systematically exceed those of GPS TEC. An empirical scale factor was derived in terms of the smoothed sunspot number, and this factor reduced the systematic excess of the TOPEX/Jason-derived IEC over the GPS TEC by a factor of 1.5 towards the solar minimum. This factor was tested with observations made at the solar minimum and revealed that the plasmaspheric electron content to be a residual of the GPS TEC and modified TOPEX/Jason IEC.
Observation of numerous aftershocks of an Mw 1.9 earthquake with an AE network installed in a deep gold mine in South Africa
Authors: Yabe Yasuo , Philipp Joachim , Nakatani Masao , Morema Gilbert , Naoi Makoto , Kawakata Hironori , Igarashi Toshihiro , Dresen Georg , Ogasawara Hiroshi ,   JAGUARS
Published: August 2014

Abstract
This is the first report from the JAGUARS (JApanese-German Underground Acoustic Emission Research in South Africa) project, the overall aim of which is to observe ultra-small fracturing in a more or less natural environment. We installed a local (∼40-m span) network of eight acoustic emission (AE) sensors, which have the capability to observe up to 200 kHz at a depth of 3.3 km in a South African gold mine. Our specific objective was to monitor a 30-m thick dyke that remains as a dip pillar against active mining ∼90 m above our network. An M
w 1.9 earthquake whose hypocenter was ∼30 m above the network occurred in the dyke. Although the mineowned geophone (4.5 Hz) network detected only five earthquakes in the surrounding 200×200×150-m3 volume within the first 150 h following the main shock, our AE network detected more than 20,000 earthquakes in the same period. More than 13,000 of these formed a distinct planar cluster (∼100×80 m2) on which the main shock hypocenter lay, suggesting that this cluster delineates the main shock rupture plane. Most of the aftershocks were presumably very small, probably as low as M ∼ −4. The aftershock cluster dipped ∼60°. This is consistent with normal faulting under a nearly vertical compression field, as indicated by nearly horizontal breakouts found in a borehole crossing the rupture plane.
Shear-wave anisotropy beneath the Ryukyu arc
Authors: Nakamura Mamoru , Yamamoto Ai 
Published: August 2014

Abstract
We have investigated regional shear-wave splitting beneath the Ryukyu arc in order to clarify the mantle flow beneath the Ryukyu arc and compare it with the extension of the Okinawa Trough. The splitting of regional shear waves (direct S) in the central and southern Ryukyu arc regions was analyzed in terms of fast-polarization direction and delay time using data from 11 short-period stations and two broadband seismic stations. The events occurred at depths ranging between 45 and 217 km, and the magnitude of the events ranged from 2.8 to 5.2. In general, the orientations of fast polarization were found to parallel to the strike of the Ryukyu Trench, with average delay times of 0.25–0.56 s. Specifically, the orientation of fast polarization was parallel to the direction of the extension in the south Ryukyu arc, suggesting that the direction of mantle flow is parallel to the extension in the south Okinawa Trough. However, the orientation of fast polarization was oblique to the direction of extension in the central Ryukyu arc, indicating that the mantle flow beneath the central Ryukyu arc is not parallel to the extension of the central Okinawa Trough. Based on these results, we suggest that the difference between the direction of the mantle flow and that of the lithosphere extension induces extensional strain with a simple shear component, which in turn causes oblique rifting in the central Okinawa Trough.
Analyzing and correcting for contaminating magnetic fields at the Brorfelde geomagnetic observatory due to high voltage DC power lines
Authors: Maule Cathrine Fox , Thejll Peter , Neska Anne , Matzka Jürgen , Pedersen Lars William , Nilsson Anna 
Published: August 2014

Abstract
The magnetic field observations made at the geomagnetic observatory Brorfelde (BFE), Denmark, are subject to disturbances of several nT caused by two single wire high-voltage DC power lines connecting Scandinavia with Central Europe. We have analysed how the magnetic disturbances relate to the currents in the power lines and found a linear relationship. Using linear regression on carefully selected parts of the available data series we have determined the factors of proportionality. Based on the simple relationship between the currents in the power lines and the observed magnetic disturbances, we have derived a method to correct the observatory data for a significant part of the disturbances. In addition we have investigated the influence of the disturbances on the determination of the K-index of the observatory. We found that the K-index based on the original disturbed data compared to the K-indices calculated from corrected data was different in 4% of the 3-hour intervals for the investigated period.
Landwater variation in four major river basins of the Indochina peninsula as revealed by GRACE
Authors: Yamamoto Keiko , Fukuda Yoichi , Nakaegawa Toshiyuki , Nishijima Jun 
Published: August 2014

Abstract
We estimated mass variations in four major river basins—the Mekong, Irrawaddy, Salween and Chao Phraya river basins—of the Indochina Peninsula using the newly released GRACE (Gravity Recovery and Climate Experiment) monthly gravity field solutions of UTCSR RL02 (University of Texas at Austin, Center for Space Research Release 02), JPL RL02 (Jet Propulsion Laboratory Release 02) and GFZ RL03 (GeoForschungsZentrum Potsdam Release 03). The estimated variations were compared with that calculated from a numerical model. The results show that there is a good agreement between the GRACE estimations and the model calculation for the Mekong and Irrawaddy basins, while the aggreement for the Salween and Chao Phraya basins is poor, mainly due to the spatial scale of the areas concerned. The comparison over the combined area of the four river basins shows fairly good agreement, although there are small quantitative discrepancies. The amplitudes of the annual signals of the GRACE solutions are 0.9- to 1.4-fold larger than that of the hydrological model, and the phases are delayed about 1 month compared with the model signal. The phase differences are probably due to improper treatments of the groundwater storage process in the hydrological model, suggesting that the GRACE data possibly provide constraints to the model parameters.
Measurement of the duration of high-frequency energy radiation and its application to determination of the magnitudes of large shallow earthquakes
Authors: Hara Tatsuhiko 
Published: August 2014

Abstract
We have developed an algorithm to measure the duration of high-frequency energy radiation by processing the first arriving P-waves and then applied it to analyses of 69 large shallow earthquakes that occurred between 1995 and 2006. We compared our estimates to time differences between centroid and origin times in the Harvard CMT catalog and found that there was a good correlation between them, thereby suggesting that the measured durations are good estimates of source durations. We show that it is possible to determine magnitudes consistent with moment magnitudes in the Harvard CMT catalog using the durations of high-frequency energy radiation and maximum displacement amplitudes of the first arriving P-waves.
Analysis of ionospheric scintillation spectra and TEC in the Chinese low latitude region
Authors: Li Guozhu , Ning Baiqi , Yuan Hong 
Published: August 2014

Abstract
GPS L-band scintillations and total electron content (TEC) were recorded at Sanya (18.33°N, 109.52°E) during the period July 2004–July 2005. Automatic recorded raw digital scintillation data are analyzed to obtain the spectral characteristics of irregularities producing ionospheric scintillations and to estimate the correlation between amplitude scintillation and power spectral density. Concurrent measurements of TEC are used to analyze ROTI, defined as the standard deviation of the rate of change of TEC. The statistical results of S4 indices and power spectral indices indicate that the power spectral indices increase with S4 indices for weak scintillation (0.1 ≤ S4 < 0.3), but for moderate and strong scintillation, spectral indices tend to be saturated. In the analyzed data set, the ratio of ROTI/S4 is found to vary between 0.3 and 6, and the variation in estimated zonal drift velocities during geomagnetic quiet days (K p < 3) shows that the motion of the irregularities is highly variable in the initial phase of irregularity development. After about 22:00 LT, the estimated drift velocities tend to follow the same pattern.
Long-term stability of climate and global glaciations throughout the evolution of the Earth
Authors: Tajika Eiichi 
Published: August 2014

AbstractEarth’s climate is considered to be stable on the order of > 106years, owing to a negative feedback mechanism in a carbon cycle system. However, any decrease in net input flux of CO2to the atmosphere-ocean system (i.e., volcanic-metamorphic CO2flux minus excess organic carbon burial flux) lowers the surface temperature and would eventually initiate global glaciation. TheFD-FOBdiagram (FD: the total CO2degassing flux,FOB: the organic carbon burial flux) is proposed as a measure of the susceptibility of the Earth to global glaciations. By using this diagram with the carbon fluxes estimated from a carbon cycle model during the Phanerozoic, the net input flux of CO2is found to have been very close to the critical condition for a global glaciation at the Late Paleozoic. During the Proterozoic, a carbon isotope mass balance model with this diagram shows that global glaciations occurred probably due to a decrease in the CO2degassing in addition to an increase in the organic carbon burial. Because the Sun becomes brighter as it evolves, the critical level of atmospheric CO2pressure to cause global glaciation will be lower than the critical CO2pressure for photosynthesis of C4 plants within 500 million years. At this point, the net input flux of CO2will be too large to cause global glaciations. Continuous volcanic-metamorphic activities (i.e., plate tectonics) may be one of the necessary conditions for the Earth and Earth-like planets in extrasolar planetary systems to keep liquid water and life over the timescales of planetary evolution.
Scaling of short-period source spectrum for earthquakes in mid Niigata, Japan
Authors: Izutani Yasuo 
Published: August 2014

Abstract
Strong motion records at K-NET and KiK-net stations for earthquakes which occurred in the mid Niigata area are analyzed to examine the relationship between the amplitude of the short-period source spectrum and the seismic moment. Large earthquakes radiate more short-period seismic energy per unit seismic moment than small ones, which suggests a deviation from the similarity of earthquake source. Appropriate correction for the deviation from the similarity should be made when we synthesize strong ground motion for future large earthquakes by the empirical Green’s function method.
Seismic moments of Taiwan’s earthquakes evaluated from a regional broadband array
Authors: Chen Kou-Cheng , Liang Wen-Tzong , Liu Yu-Hua , Huang Win-Gee , Wang Jeen-Hwa 
Published: August 2014

Abstract
We have taken the seismic moment (M
o) values of 79 earthquakes occurring in the Taiwan region that have been published in the Global centroid-moment tensor (CMT) and regional Broadband Array in Taiwan for Seismology (BATS) catalogues for the period 1996–2005 and compared the values determined from the global and regional networks, respectively. M
oG and M
oB are used to denote the M
o values published in the Global CMT and regional BATS catalogues, respectively. Our results show that M
oB linearly correlates with M
oG and that M
oB is, on average, approximately equal to 0.37M
oG. This difference may be caused by the use of shorter period seismic waves in BATS for estimating M
oB. The moment magnitude evaluated from regional BATS seismograms is about 0.3 less than that estimated from global data.
Electromagnetic full particle simulation of the electric field structure around the moon and the lunar wake
Authors: Kimura Shinya , Nakagawa Tomoko 
Published: August 2014

Abstract
The electric field structure around the moon is studied using a 2-dimensional electromagnetic full particle simulation. By considering absorption of the plasma particles at the surface of the moon, we obtain an intense electric field at the terminator region where the electric field produced by the negatively charged lunar surface and the ambipolar electric field at the wake boundary are in the same direction. The intensity of the electric field is 2.2E
0 (E
0 = m
0
υ

e

ω

p
/q0) at the terminator, corresponding to 3.5 V m−1 in the solar wind. It has a large horizontal component due to the potential difference between the negatively charged, antisolarside surface of the moon and the electrically neutral, solar-side surface, even though the emission of photoelectrons are not taken into consideration in this study. The half width of the electric field structure is of the order of Debye shielding length. The electric field at the downstream wake boundary at x = 6.5R

L
is stillas large as 0.1E
0 ∼ 0.16 V m−1, which is strong enough to cause the pitch angle diffusion of the solar-wind electron beam, as is expected in the generation mechanism of the wake-related whistler wave. The ion acceleration occurs in the close vicinity of the moon and can be explained by the acceleration by the electric field produced by the surface charging of the moon.
Comparison between the KOMPSAT-1 drag derived density and the MSISE model density during strong solar and/or geomagnetic activities
Authors: Park J. , Moon Y.-J. , Kim K.-H. , Cho K.-S. , Kim H.-D. , Kwak Y.-S. , Kim Y.-H. , Park Y.-D. , Yi Y. 
Published: August 2014

Abstract
We have compared the KOrea Multi-Purpose SATellite-1 (KOMPSAT-1) drag derived density with the MSISE model (NRLMSISE-00 and MSISE-90) density during strong solar and/or geomagnetic activities. It is well known that there are two major mechanisms to induce satellite drag caused by atmospheric density enhancement: the heating by solar EUV radiation and joule heating associated with local geomagnetic current enhancements during geomagnetic storms. For this work we select five events dominated by the radiation effect and/or the geomagnetic effect. For these events we compared the satellite drag derived density with the MSISE model density. The major results can be summarized as follows. (1) The density predicted from the MSISE models during radiation dominated periods are comparable to the drag derived density but the MSISE model density during strong geomagnetic storms is significantly underestimated when the MSISE model density is compared to the drag derived density, by about two times for the NRLMSISE-00 model. (2) The ratios of the KOMPSAT-1 (around 685 km) drag derived density to the MSISE model density during a strong geomagnetic storm are abruptly enhanced (up to a factor of about 8 for the MSISE-90 model and about 3 for the NRLMSISE-00 model), which are much larger than previous estimates from low altitude (around 400 km) satellites. (3) There is a possible correlation between daily drag enhancement and daily Dst variation. We note that there is a remarkable difference in daily drag enhancement although solar and geomagnetic activities are quite similar to each other. We suggest that such a difference should be explained by the accumulation of solar radiation effect depending on solar activity cycle.
Ice Box Calorimetry: A useful method for estimating heat discharge rates through steaming ground
Authors: Terada Akihiko , Kagiyama Tsuneomi , Oshima Hiromitsu 
Published: August 2014

Abstract
We developed a new technique, Ice Box Calorimetry, for estimating heat discharge rates through steaming ground. Ice within an aluminum box provides a powerful tool for measuring the total heat transfer from the ground surface, including conductive heat, convective heat, and latent heat within vapor. Using this method, we are able to rapidly measure heat discharge rates without the need for specialized apparatus. Applying Ice Box Calorimetry to the Nishiyama steaming ground at Usu volcano, Japan in September 2006, we identified local variations in heat discharge rates. The total heat discharged from the entire geothermal area in September 2006 is estimated to be 27 MW, which represents just 1% of the rate immediately following an eruption from the volcano in 2000.
Coseismic deformation due to the 2007 Chuetsu-oki earthquake (Mw= 6.8)
Authors: Aoki Yosuke , Furuya Masato , Kato Teruyuki 
Published: August 2014

AbstractGlobal Positioning System (GPS) and Synthetic Aperture Radar Interferometry (InSAR) detected substantial ground deformation due to the 2007 Chuetsu-oki earthquake (Mw= 6.8); GPS observation detected a horizontal deformation of up to about 170 mm and subsidence of up to 30 mm, and InSAR detected up to 290 mm of line-of-sight changes. A fault model is proposed to fit the ground deformation field as well as the aftershock distribution. Our model shows that a northwest-dipping fault to the north and a southeast-dipping fault to the south, consistent with the aftershock distribution, fits well with the observed data. However, our model also suggests that the modeled faults are likely to extend to shallower depths, where aftershocks are terminated. Combining our model with the subsurface structure suggests that the earthquake rupture initiated at depth and propagated into shallower depths that are not capable of nucleating an earthquake because of the presence of unconsolidated sediments.