bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local gravity from Lunar Prospector tracking data: Results for Mare Serenitatis
Authors: Goossens S. , Visser P. N. A. M. , Heki K. , Ambrosius B. A. C. 
Published: August 2014

Abstract
High-resolution gravity anomalies on the surface of the Moon are determined from Lunar Prospector tracking data residuals. By means of a benchmark test the recovery method is validated with respect to the orbit determination and gravity field recovery strategy. Tracking data for the entire extended mission of Lunar Prospector, during which the satellite flew at an average altitude of 30 km above the lunar surface, have been completely and independently processed and orbits have been determined. Using tracking data residuals from these precise orbits, adjustments to the a priori gravity field model have been created for Mare Serenitatis. The results for Mare Serenitatis with the local recovery are comparable to global recovery results, yet faster and more efficient with a possibility to increase the resolution.
International Geomagnetic Reference Field—the tenth generation
Authors: Macmillan Susan , Maus Stefan 
Published: August 2014

Abstract
The International Geomagnetic Reference Field (IGRF) 10th Generation was adopted in 2004 by the International Association of Geomagnetism and Aeronomy (IAGA) Working Group V-MOD. It is the latest version of a standard mathematical description of the Earth’s main magnetic field and is used widely in studies of the Earth’s deep interior, its crust and its ionosphere and magnetosphere. This generation differs from the previous generation with the replacement of the secular-variation model for 2000.0–2005.0 with a main-field model at 2005.0 and a secular-variation model for 2005.0–2010.0. The IGRF is the product of a huge collaborative effort between magnetic field modellers and the institutes involved in collecting and disseminating magnetic field data from satellites and from observatories and surveys around the world. This paper lists the new coefficients and includes contour maps and pole positions.
New parameterization of external and induced fields in geomagnetic field modeling, and a candidate model for IGRF 2005
Authors: Olsen Nils , Sabaka Terence J. , Lowes Frank 
Published: August 2014

Abstract
When deriving spherical harmonic models of the Earth’s magnetic field, low-degree external field contributions are traditionally considered by assuming that their expansion coefficient q
1
0
varies linearly with the D
st-index, while induced contributions are considered assuming a constant ratio Q
1 of induced to external coefficients. A value of Q
1 = 0.27 was found from Magsat data and has been used by several authors when deriving recent field models from Èrsted and CHAMP data. We describe a new approach that considers external and induced field based on a separation of D
st = E
st + I
st into external (E
st) and induced (I
st) parts using a 1D model of mantle conductivity. The temporal behavior of q
1
0
and of the corresponding induced coefficient are parameterized by E
st and I
st, respectively. In addition, we account for baseline-instabilities of D
st by estimating a value of q
1
0
for each of the 67 months of Èrsted and CHAMP data that have been used. We discuss the advantage of this new parameterization of external and induced field for geomagnetic field modeling, and describe the derivation of candidate models for IGRF 2005.
NGDC/GFZ candidate models for the 10th generation International Geomagnetic Reference Field
Authors: Maus Stefan , McLean Susan , Dater David , Lühr Hermann , Rother Martin , Mai Wolfgang , Choi Sungchan 
Published: August 2014

Abstract
Following the call for candidates for the 10th generation IGRF, we produced and submitted three main field and three secular variation candidate models. The candidates are derived from parent models which use a standard quadratic parameterisation in time of the internal Gauss coefficients. External magnetospheric fields are represented by combined parameterisations in Solar Magnetic (SM) and in Geocentric Solar Magnetospheric (GSM) coordinates. Apart from the daily and annual variations caused by these external fields, the model also accounts for induction by Earth rotation in a non-axial external field. The uncertainties of our candidates are estimated by comparing independent models from CHAMP and Èrsted data. The root mean square errors of our main field candidates, for the internal field to spherical harmonic degree 13, are estimated to be less than 8 nT at the Earth’s surface. Our secular variation candidates are estimated to have root mean square uncertainties of 12 nT per year. A hind-cast analysis of the geomagnetic field for earlier epochs shows that our secular acceleration estimates from post-2000 satellite data are inconsistent with pre-2000 acceleration in the field. This could confirm earlier reports of a jerk around 2000.0, with a genuine change in the secular acceleration.
The IZMIRAN main magnetic field candidate model for IGRF-10, produced by a spherical harmonic-natural orthogonal component method
Authors: Golovkov Vadim P. , Zvereva Tatiana I. , Chernova Tatiana A. 
Published: August 2014

Abstract
A simple method is proposed for constructing a space-time model of the main magnetic field based on the high-accuracy satellite survey data. At the first stage, we expand the CHAMP daily mean data into spherical harmonics with constant coefficients. It provides us with a series of the daily mean spherical-harmonic models (DMM) over a survey interval of several years, which are, then, expanded into the natural orthogonal components (NOC). It is shown that the NOC series converges rapidly, and that the accuracy of the space-time model over the time interval under consideration is no worse than the accuracy of the traditional models.
Evaluation of candidate geomagnetic field models for the 10th generation of IGRF
Authors: Maus Stefan , Macmillan Susan , Lowes Frank , Bondar Tatjana 
Published: August 2014

Abstract
The recent satellite magnetic missions, combined with high quality ground observatory measurements, have provided excellent data for main field modelling. Four different groups submitted seven main-field and eight secular-variation candidate models for IGRF-10. These candidate models were evaluated using several different strategies. Comparing models with independent data was found to be difficult. Valuable information was gained by mapping model differences, computing root mean square differences between all pairs of models and between models and the common mean, and by studying power spectra and azimuthal distributions of coefficient power. The resulting adopted IGRF main-field model for 2005.0, an average of three selected candidate models, is estimated to have a formal root mean square error over the Earth’s surface of only 5 nT, though it is likely that the actual error is somewhat larger than this. Due to the inherent uncertainty in secular variation forecasts, the corresponding error of the adopted secular-variation model for 2005.0–2010.0, an average of four selected candidate models, is estimated at 20 nT/a.
Outline of vertical displacement of the 2004 and 2005 Sumatra earthquakes revealed by satellite radar imagery
Authors: Tobita Mikio , Suito Hisashi , Imakiire Tetsuro , Kato Min , Fujiwara Satoshi , Murakami Makoto 
Published: August 2014

Abstract
Analyses of satellite radar imagery before and after the 2004 and 2005 Sumatra earthquakes reveal an overview of the uplift and submergence pattern of islands along the subduction zone and provide an outline of the regions that experienced coseismic vertical deformation. We find evidence of crustal deformation from the northern tip of the Andaman Islands to Nias Island. A line 145 km east of the trench separates western uplifted zone from eastern subsided zone. Agreement with the field observation demonstrates the feasibility of our method. We find that radar imagery analysis is more efficient for investigating vertical displacements than similar techniques using optical sensors.
Aeromagnetic constraits on the subsurface structure of the Unzen Graben, Kyushu, Japan
Authors: Okubo Ayako , Nakatsuka Tadashi , Tanaka Yoshikazu , Kagiyama Tsuneomi , Utsugi Mitsuru 
Published: August 2014

Abstract
Aeromagnetic analyses have been conducted in and around the Unzen Volcano, Kyushu, Japan, in order to reveal the subsurface structure of the Unzen graben. First, we applied a magnetization intensity mapping method to analyze the aeromagnetic anomalies of the central part of the Shimabara peninsula. Magnetization highs and lows correspond to the Older Unzen (0.15–0.5 Ma) and the Younger Unzen (<0.15 Ma), respectively. However, the Mayu-Yama volcano is exceptionally high in the Younger Unzen. Moreover, it turns out that the Pre-Unzen (>0.5 Ma) or localized hydrothermally altered areas show magnetization lows. Next, magnetic models were constructed from aeromagnetic anomalies, drilling data and the result of magnetization intensity mapping. Finally, similar to the results of other geophysical data, it turns out that the Unzen graben has the features of a half-graben, with the northern fault (the Chijiwa fault) down in the western Unzen region and the southern fault (the Futsu and Fukae fault) down in the eastern Unzen region. Moreover, it clarified that the layers of low magnetization extend to the near-surface beneath Shimo-Dake, Kami-Dake, and the Unzen hot spring. These layers of low magnetization reflect the fractured or hydrothermally altered zones caused by the upflow of geothermal convection that exists in the central part in the graben.
Rupture process of the 2005 West Off Fukuoka Prefecture earthquake obtained from strong motion data of K-NET and KiK-net
Authors: Sekiguchi Haruko , Aoi Shin , Honda Ryou , Morikawa Nobuyuki , Kunugi Takashi , Fujiwara Hiroyuki 
Published: August 2014

Abstract
We have investigated the rupture process of the 2005 West Off Fukuoka Prefecture earthquake by the multitime- window linear waveform inversion method using the strong ground motion data recorded at 11 K-NET and KiK-net stations. From the waveforms of the P-wave portion, it is indicated that the energy release in the first few seconds was markedly lower than the subsequent part, and this causes difficulty in identifying onset of the S-wave. To decide an appropriate time window for the waveform inversion, we estimate the S-wave onset using aftershock records. The inverted slip distribution shows a single asperity of 8 km × 6 km and its center located 8 km to the southeast and 6 km above the hypocenter. The asperity explains most of the large-amplitude signals in the observed waveforms. The turning point from the initial low-energy-release rupture to the main high-energyrelease rupture is estimated from the spatial variation of the observed initial rupture phase. It is found 3.3 s after the initiation of the rupture at about 4 km to the southeast of the hypocenter. Stress drop during the initial rupture is estimated to be in the same order of those of moderate size aftershocks, which indicates that the initial rupture is an ordinary dynamic rupture.
Off-fault aftershocks of the 2005 West Off Fukuoka Prefecture Earthquake: Reactivation of a structural boundary?
Authors: Imanishi Kazutoshi , Kuwahara Yasuto , Haryu Yoshikatsu 
Published: August 2014

AbstractAfter the occurrence of the 20 March 2005 West Off Fukuoka Prefecture Earthquake (Mj7.0), off-fault aftershocks occurred in and around Hakata bay adjacent to the main fault of the earthquake. The locations of the activity seem to coincide with the Ishido-Uminonakamichi fault (I-U fault), which is a structural boundary and not considered as an active fault. In order to elucidate relations between these off-fault aftershocks and the I-U fault, we determine the double-difference earthquake locations and focal mechanism solutions. Results of the present study show that the off-fault aftershocks are aligned in a sense of left-lateral faulting striking 120° from the north and in that of their conjugate right-lateral fault structures striking 30? from the north. Comparing the trends of these aligned structures with the orientation of the I-U fault, we conclude that earthquakes in and around the Hakata bay occurred along these aligned structures, not along a fault plane inferred from the surface trace of the I-U fault. The analysis of Coulomb failure stress due to the mainshock also supports this conclusion. Stress tensor inversion shows that the stress field in and around the Hakata bay is characterized by a strike-slip faulting. The angles between the fault trends and the maximum principal stress suggest that the aligned structures found in this study are favorably oriented, while the fault plane inferred from the surface trace of the I-U fault is unfavorably oriented.
Source model of the 2005 west off Fukuoka prefecture earthquake estimated from the empirical Green’s function simulation of broadband strong motions
Authors: Suzuki Wataru , Iwata Tomotaka 
Published: August 2014

AbstractWe estimated strong motion generation area (SMGA) source model which is responsible for broadband (0.2, 0.3–10 Hz) strong motions of the 2005 west off Fukuoka prefecture earthquake and its largest aftershock using the empirical Green’s function (EGF) method. The estimated SMGAs are almost corresponding to the large slip area deduced by kinematic waveform inversion. The SMGA rupture for the mainshock propagated mainly upward and toward the northwest with rupture velocity of 3.15 km/s. The size of the SMGA follows the self-similar empirical formula of the asperity size derived by Somervilleet al.(1999). The stress drop of the mainshock SMGA is calculated to be 10.7 MPa, which is larger than those of the largest aftershock SMGA and the aftershocks used as EGF.
Multi-step prediction of Dst index using singular spectrum analysis and locally linear neurofuzzy modeling
Authors: Sharifi Javad , Araabi Babak N. , Lucas Caro 
Published: August 2014

Abstract
Even one-step prediction of natural time series without delay especially in main phase of storm is difficult for many complicated time series such as Dst index. In this study, with a new method based on singular spectrum analysis, we extract the main components of the time series, model each component with a locally linear neurofuzzy network, and utilize the trained networks for multi-step ahead prediction of a validation set of data, and finally combine the predicted patterns for construction of general prediction. Our methods are compared with several previous studies for Dst index prediction. Several solar geomagnetic extreme events are predicted well with our state-of-the-art method; such as extreme events in 14 March 1989 that led to power black-out in Quebec, as well as other extreme storms.
Deriving main field and secular variation models from synthetic Swarm satellite and observatory data
Authors: Lesur Vincent , Macmillan Susan , Thomson Alan 
Published: August 2014

Abstract
We investigate how well the core field component of the underlying model used in the Swarm End-to-End simulator can be recovered when relatively simple geomagnetic field models are fitted to synthetic Swarm satellite and observatory data. In particular we demonstrate the potential benefits of Swarm by deriving models without these data. From two years of observatory data, the underlying secular variation model is recovered up to about spherical harmonic degree 8. This maximum degree is higher than was expected but increases to 10 when satellite data are also used. The constant part of the geomagnetic field model is recovered to at least degree 17. These results improve when a better statistical treatment of the data errors is made, a slightly more complex field model is fitted, or when five years of data are used.
Determining dislocation Love numbers using satellite gravity mission observations
Authors: Sun Wenke , Okubo Shuhei , Sugano Takayuki 
Published: August 2014

Abstract
This paper presents a new approach to calculate dislocation Love numbers using observations of a satellite gravity mission (e.g. GRACE). The necessary condition is that the co-seismic potential change be sufficiently large to be detected by the gravity mission. Co-seismic deformations for each spherical harmonic degree n are decoupled. Therefore, dislocation Love numbers of degree n can be determined independently. The determinable maximum harmonic degree n depends on the seismic size, source type, magnitude, and the accuracy of a satellite gravity mission. For an arbitrary seismic source, all four types of dislocation Love numbers can be determined using data from only one seismic event because all deformation components are involved together. Only the concerned dislocation Love numbers can be computed for any one of the four types of sources. To prove the validity of the method proposed in this study, a simulation test is carried out by considering a similar case to the 2004 Sumatra earthquake (Mw 9.1). Results show that the method works well and guarantee the accuracy.
Behavior of fluorine and chlorine in volcanic ash of Sakurajima volcano, Japan in the sequence of its eruptive activity
Authors: Nogami Kenji , Iguchi Masato , Ishihara Kazuhiro , Hirabayashi Jun-ichi , Miki Daisuke 
Published: August 2014

Abstract
At Sakurajima volcano, strombolian eruptions forerun vulcanian explosions, and volcanian explosions are often followed by continuous ash eruptions. Change in the mode of its eruptive activity is drastic and release of volatiles from magma corresponding to its eruptive activity is examined by determination of fluorine and chlorine in volcanic ash. The F contents of all the ash samples are markedly higher than the arithmetic mean value of Japanese volcanic rocks (ca. 300 μg/g). Further, the water-soluble Cl contents of almost all the ash samples are also extremely higher than those of Japanese volcanic rocks (less than 50 μg/g). This is attributed to fixation of F and Cl in hot gas onto the volcanic ash particles in the crater and/or eruption plumes. The differences in those contents among the “strombolian eruption”-, “vulcanian explosion”- and “continuous ash eruption” groups are significant, which implies that hot gas rich in F and Cl are issued during strombolian eruptions, while those halogens are less concentrated in hot gas after strombolian eruptions. The water-insoluble Cl content of the “strombolian eruption” group is significantly higher than those of the other groups. This result implies that Cl and the other volatiles are intensely released from magma during the doming period before vulcanian eruptions.
Yet, it is inferred that continuous ash eruption is the final phase of vulcanian one.
A significant mass density increase during a large magnetic storm in October 2003 obtained by ground-based ULF observations at L ≈ 1.4
Authors: Takasaki Satoko , Kawano Hideaki , Tanaka Yoshimasa , Yoshikawa Akimasa , Seto Masahiro , Iizima Masahide , Obana Yuki , Sato Natsuo , Yumoto Kiyohumi 
Published: August 2014

Abstract
During 28–31 October, 2003, a series of coronal mass ejections hit the magnetosphere and triggered two consecutive large storms. Three ground magnetometers at L = 1.32–1.41 recorded field-line resonances (FLRs) during this interval. The FLR frequencies decreased from 0600 LT on 31 October 2003 during the main phase of the second storm until 12 LT when the recovery phase of this storm began. After the decrease, the FLR frequencies returned to its pre-storm value (at 0600 LT on 31 Oct.) in a few hours. The measured decrease in the FLR frequency suggests a relative increase in mass density along the field lines during the magnetic storm. On the other hand, the total electron content (TEC) data suggest that the ionospheric plasma number density during this storm was similar to that during quiet times. A possible explanation for the increase in mass density would be an outflow of the heavy ions (e.g., O+) from the ionosphere to the plasmasphere.
Influence of the interplanetary magnetic field on the ring current injection rate
Authors: Aoki Takao 
Published: August 2014

Abstract
In order to check the validity of Akasofu’s ε parameter and of the Vasyliunas et al. (1982) general formula, we examine the dependence of the ring current injection rate, calculated from the Dst index for the period of 1965–1990, on the interplanetary magnetic field (IMF). We compare the influence of the Bz component with the influence of the combination of sin(θ/2), where θ is the IMF clock angle, and the IMF magnitude, B, (or the transverse component of the IMF, BT = (By2 + Bz2)1/2) by using the regression analysis in a power law form. The main results are as follows: (1) the exponent for Bz shows higher consistency than that for sin(θ/2); (2) we never obtain B
2 sin4(θ/2) or B
T
2 sin4(θ/2), which is the IMF dependence expected from the ε parameter; and (3) the ring current injection rate has a very low correlation with the Alfven Mach number, from which the IMF dependence of the Vasyliunas et al. general formula is assumed to arise. On the basis of the above results we conclude that the ε parameter and the Vasyliunas et al. general formula are less appropriate than a function of Bz, and that the energy coupling function between the solar wind and the Earth’s magnetosphere is described better by Bz than by the combination of B (or B
T) and sin(θ/2). The above results and conclusions are the same as those obtained by Aoki (2005) through the analysis of the AL index.
Longitudinal dependence of characteristics of low-latitude Pi2 pulsations observed at Kakioka and Hermanus
Authors: Nosé M. , Liou K. , Sutcliffe P. R. 
Published: August 2014

AbstractWe statistically investigated longitudinal dependence of characteristics of low-latitude Pi2 pulsations to find the longitudinal structure of the plasmaspheric cavity mode. We used the geomagnetic field data from two ground stations, Kakioka (27.2° geomagnetic latitude, 208.5° geomagnetic longitude) and Hermanus (—33.9° geomagnetic latitude, 82.2° geomagnetic longitude), and auroral image data acquired by the ultraviolet imager onboard the Polar satellite for the period of December 4, 1996 to March 3, 1997. Our findings include the following: (1) Pi2 amplitude is the largest around the magnetic local time of the auroral breakup site and decreases away from it; (2) when a nightside Pi2 pulsation has large amplitude, a dayside Pi2 pulsation can be observed with a similar waveform; (3) Pi2 pulsations generally have no clear phase differences (mean phase difference of 3.3°) between Kakioka and Hermanus, except for some events; and (4) the phase difference is independent on AMLT (difference of magnetic local time between a station and the auroral breakup). These observations suggest that the plasmaspheric cavity mode can be excited globally with a very small value of the azimuthal wave number(m≈0).
Annual and semi-annual variations of the geomagnetic field components analysed by the multi-taper method
Authors: Wardinski I. , Mandea M. 
Published: August 2014

Abstract
Monthly means of three geomagnetic components (X-northern, Y-eastern and Z-vertical downward) from 154 observatories over the interval 1960-2002 have been analysed to determine the annual and semi-annual variations. The method applied is a multi-taper analysis, which gives a robust estimate of the power spectral density of the temporal variation of the field components. The main objective is to investigate the geographic dependence of the annual and semi-annual variations. Surprisingly, these variations in the vertical downward component are not homogeneously distributed all over the globe, having mainly a longitudinal dependency. The results of the analysis are briefly discussed with regard to possible mechanisms responsible for these variations and to mantle conductivity.