Scale factor calibration of a superconducting gravimeter at Esashi Station, Japan, using absolute gravity measurements     

Y. Tamura  T. Sato  Y. Fukuda  T. Higashi 《Journal of Geodesy》2005,78(7-8):481-488

The scale factor of a superconducting gravimeter (SG) at the Esashi Earth Tides Station, Japan, was revised by repeating co-located absolute gravity measurements with an FG5 gravimeter. Although the calibration results from the absolute gravimeter (AG) show an apparent secular change in the scale factor of the SG (0.4% for the period 1993–2002), the relative scale factors, which are determined by tidal analysis with the response method, indicate that it has changed by no more than 0.01% during the above period. If the mean scale factor over the 10 years is adopted, a value of –56.082±0.029 Gal/V (1 Gal =10^–8 m s^–2) is obtained, which is about 0.4% smaller than that used in the global geodynamics project (GGP) database. Based on this newly determined scale factor, the tidal gravity factors at Esashi have been re-estimated. The observed tidal factors, corrected for the ocean tide effects with recent models, indicate that the theoretical gravity factors for an inelastic Earth model are more consistent with the observations than are those for an elastic model.  相似文献   

SH Waves in a Transversely Isotropic Medium–II Transradial!? Isotropic Cylinder     

R. Sato  E. R. Lapwood 《Geophysical Journal International》1968,16(5):461-473

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Responses of the polar ionosphere to the Bastille Day solar event   总被引：1，自引：0，他引：1  

Liu  Rui-yuan  Hu  Hong-qiao  Liu  Yong-hua  Xu  Zhong-hua  Sato  N.  Fraser  B.J. 《Solar physics》2001,204(1-2):305-313

Simultaneous observations at Zhongshan Station, Antarctica, are presented for the interval of 13–17 July 2000 to show responses of the polar ionosphere to the Bastille Day (14 July 2000) solar event. The polar ionosphere was highly disturbed, as shown by frequently large deviations of the geomagnetic H-component, large riometer absorption events and strong ULF waves. Associated with the huge solar proton event produced by the X5/3B flare, a polar cap absorption (PCA) was observed. It began at ∼ 10:40 UT on 14 July and ended at ∼ 19:40 UT on 17 July. Superposed on it, there was a large absorption event with a peak of 26 dB, starting at ∼ 03:00 UT and ending at ∼ 11:10 UT on 15 July. This kind of absorption was probably produced by an intense `cloud of energetic electrons' during an auroral substorm. The ULF waves were very intense during the main phase and the recovery phase of the severe magnetic storm on 15 and 16 July. The ionospheric absorption was so strong that the digisonde signal was blacked out most of the time. The ionosphere returned to normal in the afternoon on 17 July.  相似文献   

A planetary companion orbiting the intermediate-mass G Giant HD 173416     

Yu-Juan Liu Bun＇ei Sato Gang Zhao Hiroyasu Ando 《中国天文和天体物理学报》2009,9(1)

The discovery of a planetary companion to the intermediate-mass late-type giant star HD173416 from precise Doppler surveys of G and K giants at Xingiong station and Okayama Astrophysical Observatory (OAO) is presented in this letter. The planet has a minimum mass of 2.7 MJ an eccentricity of 0.21, a semimajor axis of 1.16 AU and an orbital period of 324 days.  相似文献   

Automated cloud tracking system for the Akatsuki Venus Climate Orbiter data     

Kazunori Ogohara  Toru Kouyama  Hiroki Yamamoto  Naoki Sato  Masahiro Takagi  Takeshi Imamura 《Icarus》2012,217(2):661-668

Japanese Venus Climate Orbiter, Akatsuki, is cruising to approach to Venus again although its first Venus orbital insertion (VOI) has been failed. At present, we focus on the next opportunity of VOI and the following scientific observations.We have constructed an automated cloud tracking system for processing data obtained by Akatsuki in the present study. In this system, correction of the pointing of the satellite is essentially important for improving accuracy of the cloud motion vectors derived using the cloud tracking. Attitude errors of the satellite are reduced by fitting an ellipse to limb of an imaged Venus disk. Next, longitude–latitude distributions of brightness (cloud patterns) are calculated to make it easy to derive the cloud motion vectors. The grid points are distributed at regular intervals in the longitude–latitude coordinate. After applying the solar zenith correction and a highpass filter to the derived longitude–latitude distributions of brightness, the cloud features are tracked using pairs of images. As a result, we obtain cloud motion vectors on longitude–latitude grid points equally spaced. These entire processes are pipelined and automated, and are applied to all data obtained by combinations of cameras and filters onboard Akatsuki. It is shown by several tests that the cloud motion vectors are determined with a sufficient accuracy. We expect that longitude–latitude data sets created by the automated cloud tracking system will contribute to the Venus meteorology.  相似文献   

Metal flux as an alternative parameter in evaluating the resource potential for co-rich ferromanganese crusts     

Hisaaki Sato 《Marine Georesources & Geotechnology》2018,36(7):768-780

We propose a geochemical parameter, “metal flux” in evaluating hydrogenetic Co-rich ferromanganese crust deposits in the Pacific seamount area, that is based on physical, chemical, and geological characterization of the integrated growth piles of crusts. We calculated the metal flux for fifteen sites from different depths ranging between 900-6000m from different seamounts. The secular and areal variations of metal flux indicate a strong geological controls, and also can be a reliable tool for estimating an economic potential of the crusts. The Co flux decreases with increasing water depth, followed by almost constant flux of Ni and Mn. The Al and Fe fluxes vary with regions, indicating higher values in the western regions near the island arc probably related to a supply from the Asian continents. The results imply that Co, a redox sensitive metal element, is controlled by redox conditions of seawater, while Fe and Al are by terrigenous input. The metal flux reflects global and regional conditions and controls the compositional diversity of metals, thus consequently, the parameter can be a reliable powerful tool to estimate or single out more potential areas.  相似文献   

What motivates single women to migrate from northern Ghana to Accra?     

Theresa Tufuor  Chizu Sato 《Norsk geografisk tidsskrift. Norwegian journal of geography》2017,71(1):46-59

In recent decades there has been a large migration stream of single women from the north to Accra in Ghana. Existing studies have focused on young migrant women’s livelihood strategies in their place of destination. However, once-married women – divorced and widowed women and neglected wives – also migrate, and their motivations for migration are less known. Drawing on qualitative and quantitative methods, the authors investigate the effects of gender norms, age, marital status, socio-economic status, and position in households on women’s decisions to migrate. The results revealed that migrant women from resource-poor households, regardless of age, marital status and position in households, commonly cited a gain in autonomy as an important motivation for their migration. From a differentiated perspective, young unmarried women aspired to prepare themselves for often expensive religious marriage ceremonies, whereas once-married women invest in their children’s education and build their own housing. By paying attention to the effects of gender norms, age, marital status, socio-economic status, and position in households on women’s decisions to migrate, the study illuminates the contradictory ways in which their migration practices are both shaped by and shape gender ideologies in parts of contemporary northern Ghana.  相似文献   

Growth stimulation and inhibition of natural phytoplankton communities by model organic ligands in the western subarctic Pacific     

Yoshiko Kondo  Shigenobu Takeda  Jun Nishioka  Mitsuhide Sato  Hiroaki Saito  Koji Suzuki  Ken Furuya 《Journal of Oceanography》2013,69(1):97-115

The influence of organic ligands on natural phytoplankton growth was investigated in high-nitrate low-chlorophyll (HNLC) waters and during a phytoplankton bloom induced by a mesoscale iron enrichment experiment (SEEDS II) in the western subarctic Pacific. The growth responses of the phytoplankton in the treatments with iron complexed with model ligand were compared with those with inorganic iron or a control. Desferrioxamine B and protoporphyrin IX were used as models for hydroxamate-type siderophore and tetrapyrrole-type cell breakdown ligand, respectively. In the HNLC water, iron associated with protoporphyrin IX especially stimulated smaller phytoplankton (<10 μm) growth, 1.5-fold more than did inorganic iron. Surprisingly, only the addition of protoporphyrin IX stimulated small phytoplankton growth, suggesting that these cell breakdown ligands might be more bioavailable for them. The protoporphyrin IX’s stimulatory effect on small phytoplankton was not observed during bloom decline phase. The growth of phytoplankton was inhibited in the treatment with desferrioxamine B-complexed iron, suggesting its low bioavailability for the natural phytoplankton community. Its inhibitory effects were particularly pronounced in pico-eukaryotic phytoplankton. During the iron-induced bloom, the phytoplankton’s iron-stress response gradually increased with the desferrioxamine B concentration, suggesting that the competition for iron complexation between natural ligands and desferrioxamine B affected phytoplankton growth. However, the pico-eukaryotes did seem better able to utilize the desferrioxamine B-complexed iron during the bloom-developing phase. These results indicate that the iron bioavailability for phytoplankton differs between bloom-developing and bloom-decline phases.  相似文献   

Re-Suspension Technique for Improving Organic Rich Sediment-Water Quality in a Shallow Sea Area     

Masaharu Fukue  Koji Uehara  Yoshio Sato  Catherine Mulligan 《Marine Georesources & Geotechnology》2013,31(3):222-233

The re-suspension method consists of (1) dispersion of the sediment by air-water jets, (2) pumping of the suspension (small particles and organic matter), (3) settlement in a tank, (4) filtration and (5) disposal of solids (followed by incineration in this case). The pilot test was performed to clean up an area of 3000 m². The dispersed depth of the bottom was approximately 50 cm. The time spent for the work was two weeks. The amount of re-suspended solid removed from the bottom was about 8 tonnes in dry mass. Since the solids contain high concentrations of chemical oxygen demand (COD), total phosphorous (T-P), total nitrogen (T-N) and sulfides, the remaining sediment was considerably improved. Quantitative analyses showed that the full-scale implementation would enable the removal of about 10% of the re-suspended solids, and reduce COD by 95%, T-P by 50%, T-N by 100% and sulfide by 75% for re-deposited sediments in comparison to the original sediments.  相似文献   

Synthesis of coda wave envelopes in randomly inhomogeneous elastic media in a half-space: single scattering model including Rayleigh waves     

Takuto Maeda  Haruo Sato  Takeshi Nishimura 《Geophysical Journal International》2008,172(1):130-154

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