Schumann resonance observation in China and anomalous disturbance possibly associated with Tohoku M9.0 earthquake     

Xinyang Ouyang  Xuemin Zhang  A. P. Nickolaenko  M. Hayakawa  Xuhui Shen  Yuanqing Miao 《地震科学（英文版）》2013,26(2):137-145

Schumann resonance (SR) is an electromagnetic resonance phenomenon in the Earth–ionosphere cavity exited by global lightning activities when the wavelength matches the circumference of the Earth, and the lowest four peak frequencies of SR are about 8, 14, 20, and 26 Hz. This article presents the new observational data of SR in China. The observations of two horizontal magnetic components (B _NS and B _EW) in the frequency band range of 3–29 Hz at Yongsheng observatory (26.7°N, 100.8°E) in southwestern China were mainly analyzed. It is found that the SR amplitudes at peak frequencies in B _NS and B _EW components all showed diurnal and seasonal variations, and that the SR amplitude in B _NS component is always higher than that in B _EW component. Diurnal variation of SR amplitude around equinoxes and solstices in B _NS component is related to active intervals of three global thunderstorm centers, while SR amplitude in B _EW component is the most significant at around 16 LT, corresponding to Asian center. SR amplitudes both in B _NS and B _EW components increase in the rainy season from May to September. In addition, the SR anomalies in association with the 2011 Japan earthquake are exhibited. The anomalous effect was characterized by an increase in amplitude at the lowest four SR modes beginning at 4 days before this earthquake. Upon analyzing the wave interference between the direct wave and disturbed wave scattered by localized modification of lower ionosphere over the epicenter, Asian and African thunderstorm centers are found to contribute to anomalous effect observed at Yongsheng station. Modeling results of SR regular and disturbed spectra at different local times led to the similar conclusion.  相似文献   

Factors controlling nitrogen and dissolved organic carbon exports across timescales in two watersheds with different land uses          下载免费PDF全文

Rui Jiang  Ryusuke Hatano  Ying Zhao  Kanta Kuramochi  Atsushi Hayakawa  Krishna P. Woli  Mariko Shimizu 《水文研究》2014,28(19):5105-5121

Investigating factors controlling the temporal patterns of nitrogen (N) and dissolved organic carbon (DOC) exports on the basis of a comparative study of different land uses is beneficial for managing water resources, especially in agricultural watersheds. We focused our research on an agricultural watershed (AW) and a forested watershed (FW) located in the Shibetsu watershed of eastern Hokkaido, Japan, to investigate the temporal patterns of N and DOC exports and factors controlling those patterns at different timescales (inter‐annual, seasonal, and hydrological event scales). Results showed that the annual patterns of N and DOC exports significantly varied over time and were probably controlled by climate. Higher discharge volumes in 2003, a wet year, showed higher N and DOC loadings in both watersheds. However, this process was also regulated by land use associated with N inputs. Higher concentrations and loadings were shown in the agricultural watershed. At the seasonal scale, N and DOC exports in the AW and the FW were more likely controlled by sources associated with land use. The Total N (TN) and Nitrate‐N (NO₃^?‐N) had higher concentrations during snowmelt season in the AW, which may be attributed to manure application in late autumn or early winter in the agricultural watershed. Concentrations of TN, NO₃^?‐N, dissolved organic nitrogen (DON), and DOC showed higher values during the summer rainy season in the FW, related to higher litter decomposition during summer and autumn and the fertilizer application in the agricultural area during summer. Higher DOC concentrations and loadings were observed during the rainy season in the AW, which is probably attributed to higher DOC production related to temperature and microbial activity during summer and autumn in grasslands. Correlations between discharge and concentrations differed during different periods or in different watersheds, suggesting that weather discharge can adequately represent the fact that N export depends on N concentrations, discharge level, and other factors. The differing correlations between N/DOC concentrations and the Si concentration indicated that the N/DOC exports might occur along different flow paths during different periods. During baseflow, the high NO₃^?‐N exports were probably derived from deep groundwater and might have percolated from uplands during hydrological events. During hydrological events, NO₃^?‐N exports may occur along near‐surface flow paths and in deep groundwater, whereas DOC exports could be related to near‐surface flow paths. At the event scale, the relationships between discharge and concentrations of N and DOC were regulated by antecedent soil moisture (shallow groundwater condition) in each watershed. These results indicated that factors controlling N and DOC exports varied at different timescales in the Shibetsu area and that better management of manure application during winter in agricultural lands is urgently needed to control water pollution in streams. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Selenium substitution effect on crystal structure of stibnite (Sb2S3)     

Atsushi Kyono  Akinobu Hayakawa  Mayumi Horiki 《Physics and Chemistry of Minerals》2015,42(6):475-490

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Spatial correspondence of knickzones and stream confluences along bedrock rivers in Japan: implications for hydraulic formation of knickzones     

Yuichi S. Hayakawa  Takashi Oguchi 《Geografiska Annaler: Series A, Physical Geography》2014,96(1):9-19

Knickzones, defined here as locally steep reaches including distinct knickpoints, in bedrock river morphology, have often been investigated in relation to local anomalies in lithology, tectonics, hydraulics, climate and associated base‐level change, and/or deformation of valley‐side slopes. However, exact formative causes of many knickzones in a humid, tectonically active island arc remain unclear. Using databases of geology, streams and knickzones, we examine knickzone distribution across the Japanese Archipelago to evaluate the effects of the stream network structure and rock type boundaries on knickzone formation. Knickzones are frequently found just upstream and downstream of major stream confluences along mainstreams, whereas knickzones are less frequent around major rock type boundaries. While the major confluences do not form hanging valleys due to similar catchment size, this observation suggests that many knickzones have been formed by the long‐term effect of flow turbulence scouring bedrock at the confluences. Such a hydraulic control on bedrock erosion in the steep Japanese mountains under humid climate conditions indicates that the formative cause of many knickzones therein can be autogenic by means of stream hydraulics.  相似文献   

Validation of global ocean tide models using the superconducting gravimeter data at Syowa Station, Antarctica, and in situ tide gauge and bottom-pressure observations     

Tae-Hee Kim  Kazuo Shibuya  Koichiro Doi  Yuichi Aoyama  Hideaki Hayakawa 《Polar Science》2011,5(1):21-39

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Ionospheric plasma acceleration at Mars: ASPERA-3 results     

R. Lundin  D. Winningham  R.A. Frahm  M. Holmström  M. Yamauchi  J.R. Sharber  A. Fedorov  J.-J. Thocaven  H. Hayakawa  D.R. Linder  C. Curtis  B.R. Sandel  M. Carter  H. Koskinen  P. Riihelä  T. Säles  N. Krupp  M. Fränz  S. McKenna-Lawler  S. Orsini  E. Roelof  S. Livi  P. Wurz 《Icarus》2006,182(2):308-319

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on-board the Mars Express spacecraft (MEX) measured penetrating solar wind plasma and escaping/accelerated ionospheric plasma at very low altitudes (250 km) in the dayside subsolar region. This implies a direct exposure of the martian topside atmosphere to solar wind plasma forcing leading to energization of ionospheric plasma. The ion and electron energization and the ion outflow from Mars is surprisingly similar to that over the magnetized Earth. Narrow “monoenergetic” cold ion beams, ion beams with broad energy distributions, sharply peaked electron energy spectra, and bidirectional streaming electrons are particle features also observed near Mars. Energized martian ionospheric ions (O⁺, O⁺₂, CO⁺₂, etc.) flow in essentially the same direction as the external sheath flow. This suggests that the planetary ion energization couples directly to processes in the magnetosheath/solar wind. On the other hand, the beam-like distribution of the energized plasma implies more indirect energization processes like those near the Earth, i.e., energization in a magnetized environment by waves and/or parallel (to B) electric fields. The general conditions for martian plasma energization are, however, different from those in the Earth's magnetosphere. Mars has a weak intrinsic magnetic field and solar wind plasma may therefore penetrate deep into the dense ionospheric plasma. Local crustal magnetization, discovered by Acuña et al. [Acuña, M.J., Connerey, J., Ness, N., Lin, R., Mitchell, D., Carlsson, C., McFadden, J., Anderson, K., Rème, H., Mazelle, C., Vignes, D., Wasilewski, P., Cloutier, P., 1999. Science 284, 790-793], provide some dayside shielding against the solar wind. On the other hand, multiple magnetic anomalies may also lead to “hot spots” facilitating ionospheric plasma energization. We discuss the ASPERA-3 findings of martian ionospheric ion energization and present evidences for two types of plasma energization processes responsible for the low- and mid-altitude plasma energization near Mars: magnetic field-aligned acceleration by parallel electric fields and plasma energization by low frequency waves.  相似文献   

Measurement of the absolute intensity of cosmic X-rays     

M. Matsuoka  M. Oda  Y. Ogawara  S. Hayakawa  T. Kato 《Astrophysics and Space Science》1969,4(1):44-63

The intensity of the diffuse component of cosmic X-rays was measured with use of a rotating collimator system borne on a sounding rocket. A part of background counts proportional to the field of view of proportional counters enabled us to determine the intensity of the diffuse component to be 0.66±0.07 photons cm^–2 sec^–1 keV^–1 in the energy range between 3.6 and 9.0 keV. The spectrum in this energy range was found to be comparatively flat. The intensity of Sco X-1 was also measured and its time variation was investigated.  相似文献   

Spatial fine structure of model electric pulses in the mesosphere above a Γ-shaped stroke of lightning     

I.G. Kudintseva  A.P. Nickolaenko  M. Hayakawa 《Journal of Atmospheric and Solar》2009,71(5):603-608

The fine structure is discussed arising in the spatial distribution of the pulsed electric field above a Γ-shaped stroke of lightning. The channel of discharge contains a vertical and a horizontal section. The structured spatial distribution of field appears due to a superposition of three pulses arriving from vertical and horizontal sections of the causative discharge and from reflections from the ground. The details of electric field distribution depend on time and on the stroke orientation relative to an elevated observer. The characteristic size of ‘filaments’ in the transient electric field is about 1 km along the horizontal direction, while it reaches a few tens of kilometers along the vertical direction.  相似文献   

Correlation between the densities of X-ray sources and interstellar gas     

M. Fujimoto  S. Hayakawa  T. Kato 《Astrophysics and Space Science》1969,4(1):64-83

The distribution of X-ray sources in our galaxy is obtained, assuming that the absolute X-ray luminosities of these sources are the same. The distribution is found to be in good correlation with the distribution of interstellar gas. The density of X-ray sources is nearly proportional to the square density of gas. This indicates that X-ray sources are comparatively young. The relation between the densities of X-ray sources and gas allows us to estimate the X-ray intensities of various objects such as Magellanic Clouds and Andromeda nebula, and also to obtain the average X-ray luminosity of spiral galaxies. The latter should increase as the age of a galaxy decreases, since the amount of gas decreases as the galaxy evolves. Under the assumptions that the gas density is inversely proportional to the age and that galaxies older thant ₀/30 are visible in X-rays, wheret ₀ is the present age of the universe, the contribution of X-ray sources in distant galaxies to the background component is calculated. The intensity and the spectrum of the background component of X-rays thus obtained are in fair agreement with observed ones in the energy range between 1 and 4 keV but significantly deviate from the latter at high energies.  相似文献   

X-ray emissions from Vela X-1 during its eclipsing period     

N. Sato  S. Hayakawa  F. Nagase 《Astrophysics and Space Science》1986,119(1):81-84

The X-ray pulsar Vela X-1 was observed with TENMA throughout the entire period of eclipse in March 1984. The energy spectra at several phase angles showed the iron emission line at about 6.4 keV throughout the eclipse of Vela X-1 and its intensity at the mid-eclipse to be about 10% of that in the non-eclipsing phase, whereas the continuum intensity was about 1%. The result provides means of studying the contribution of the stellar wind to the fluorescence line and the structure of the stellar atmosphere.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.  相似文献