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71.
Toshio Fukushima Masa-Katsu Fujimoto Hiroshi Kinoshita Shinko Aoki 《Celestial Mechanics and Dynamical Astronomy》1986,38(3):215-230
The relation between the units and readings of time and space coordinates of terrestrial and barycentric reference frames is discussed from the viewpoint of general relativity. Attention is paid to the unit of space coordinates since the International Astronomical Union (IAU) regulates only the unit of time in the above two frames. Two definitions of unit of length are examined and their effects on the numerical expression of coordinate transformation, equations of planetary motions, and those for light propagation time are discussed. A clear conflict is found between the IAU (1976) recommendation on the definition of the time-scales in different frames of reference and the statement that all constants in the IAU (1976) new system of astronomical constants are defined in terms of the Internationsl System of units (SI units). One of the above two definitions is proposed to resolve this conflict by the least alteration to current procedures for analysing the recent astrometric observations such as the radar/laser rangings, the range and range-rate, and the very long baseline interferometric observations. Also, an interpretation of numerical values in the IAU (1976) new system of astronomical constants is presented. It is stressed that the definition proposed in this paper requires that a formula slightly different from that in current use be employed in the numerical transformation of readings of coordinates between the terrestrial and barycentric reference frames. 相似文献
72.
73.
Naoto Iwasaka Toshio Suga Kensuke Takeuchi Keisuke Mizuno Yasushi Takatsuki Kentaro Ando Taiyo Kobayashi Eitarou Oka Yasuko Ichikawa Motoki Miyazaki Hiroshi Matsuura Kenji Izawa Chan-Su Yang Nobuyuki Shikama Momoko Aoshima 《Journal of Oceanography》2003,59(1):119-127
We deployed two profiling floats in the region south of the Kuroshio Extension in March 2000. Temperature and salinity profiles
from a depth of 1500 × 104 Pa to the surface are reported every two and four weeks, respectively. The floats performed very well for first four months
after deployment. Later they failed in surfacing for a few months when the sea surface temperature in the region was high.
The salinity sensors seemed to suffer from some damage during their failure-in-surfacing period. Despite this trouble, the
results clearly demonstrate that the profiling float is a very useful and cost-effective tool for physical oceanographic observation
in the open sea.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
74.
When Kozai (1962) studied the secular resonance of asteroids, he found the so-called Kozai resonance and expressed the analytical
solution with the use of Weierstrass ℘. Here we discuss the case where the disturber is outside a disturbed body and give
the analytical solution of the eccentricity, the inclination and the argument of pericenter with the use of the Jacobi elliptic
functions, which are more familiar than the Weierstrass ℘. Then we derive the Fourier expansion of the longitude of node and
the mean anomaly. The analytical expressions obtained here can be used for any value of the eccentricity and the inclination.
Finally we applied these analytical expressions to several dynamical systems – Nereid, that is a highly eccentric satellite
of Neptune, and newly discovered retrograde satellites of Uranus.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
75.
Thomas Hobiger Youhei Kinoshita Shingo Shimizu Ryuichi Ichikawa Masato Furuya Tetsuro Kondo Yasuhiro Koyama 《Journal of Geodesy》2010,84(9):537-546
Numerical weather models offer the possibility to compute corrections for a variety of space geodetic applications, including
remote sensing techniques like interferometric SAR. Due to the computational complexity, exact ray-tracing is avoided in many
cases and mapping approaches are applied to transform vertically integrated delay corrections into slant direction. Such an
approach works well as long as lateral atmospheric gradients are small enough to be neglected. But since such an approximation
holds only for very rare cases it is investigated how horizontal gradients of different atmospheric constituents can evoke
errors caused by the mapping strategy. Moreover, it is discussed how sudden changes of wet refractivity can easily lead to
millimeter order biases when simplified methods are applied instead of ray-tracing. By an example, based on real InSAR data,
the differences of the various troposphere correction schemes are evaluated and it is shown how the interpretation of the
geophysical signals can be affected. In addition, it is studied to which extend troposphere noise can be reduced by applying
the exact ray-tracing solution. 相似文献
76.
We perform numerical simulations to study the secular orbital evolution and dynamical structure of the quintuplet planetary system 55 Cancri with the self-consistent orbital solutions by Fischer and coworkers. In the simulations, we show that this sys-tem can be stable for at least 108 yr. In addition, we extensively investigate the planetary configuration of four outer companions with one terrestrial planet in the wide region of 0.790 AU ≤ a ≤ 5.900 AU to examine the existence of potential asteroid structure and Habitable Zones (HZs). We show that there are unstable regions for orbits about 4:1, 3:1 and 5:2 mean motion resonances (MMRs) of the outermost planet in the system, and sev-eral stable orbits can remain at 3:2 and 1:1 MMRs, which resembles the asteroid belt in the solar system. From a dynamical viewpoint, proper HZ candidates for the existence of more potential terrestrial planets reside in the wide area between 1.0 AU and 2.3 AU with relatively low eccentricities. 相似文献
77.
Chiho Sukigara Toshio Suga Toshiro Saino Katsuya Toyama Daigo Yanagimoto Kimio Hanawa Nobuyuki Shikama 《Journal of Oceanography》2011,67(1):77-85
A profiling float equipped with a fluorimeter, a dissolved oxygen (DO) sensor, and temperature and salinity sensors was deployed
in the subtropical mode water (STMW) formation region of the North Pacific. It acquired quasi-Lagrangian, 5-day-interval time-series
records from March to July 2006. The time-series distribution of chlorophyll showed a sustained and sizable subsurface maximum
at 50–100 m, just above the upper boundary of the STMW, throughout early summer (May–July). The DO concentration in this lower
euphotic zone (50–100 m) was almost constant and supersaturated in the same period, becoming more supersaturated with time.
On the other hand, the DO concentration at 100–150 m near the upper boundary of the STMW decreased much more slowly compared
with the main layer of STMW below 150 m, even though oxygen consumption by organisms was expected to be larger in the former
depth range. The small temporal variations of DO in the lower euphotic zone and near the upper boundary of the STMW were reasonably
explained by downward oxygen transport because of large diapycnal diffusion near the top of the STMW. Assuming that the oxygen
consumption rate at 100–150 m was the same as that in the main layer of STMW and compensated by the downward oxygen flux,
the diapycnal diffusivity was estimated to be 1.7 × 10−4 m2 s−1. Nitrate transport into the euphotic zone by the same large diffusion was estimated to be 0.8 mmol N m−2 day−1. All of the transported nitrate could have been used for photosynthesis by the phytoplankton; net community production was
estimated to be 5.3 mmol C m−2 day−1. 相似文献
78.
Yoshiaki Kon Mihoko Hoshino Kenzo Sanematsu Sayaka Morita Maiko Tsunematsu Nobuyuki Okamoto Nobuhiko Yano Mikiya Tanaka Tetsuichi Takagi 《Resource Geology》2014,64(1):47-57
We have conducted geochemical and mineralogical investigations of the rare earth and yttrium (REY)‐rich mud from the Minami‐Torishima area in the Pacific in order to clarify the concentration of REY and their host‐phase in the mud. X‐ray diffraction analysis shows that the mud is mainly composed of phillipsite, fluorapatite, quartz, albite, illite and montmorillonite. Whole‐rock CaO, P2O5 and total REY contents of the mud are positively correlated. Relative abundance of apatite is also positively correlated to P2O5 and total REY contents. These correlations suggest that apatite is the main host of the P2O5 and REY in the mud. We make in situ compositional analyses of constituent minerals in the REY mud. The results show that the apatite is abundant in REY (9300–32,000 ppm) and is characterized by a negative Ce anomaly and enrichment in heavy rare‐earth elements. This abundance and composition of REY of the mud is similar those of fish debris apatites. In contrast, phillipsite is less abundant in REY (60–170 ppm). Therefore we conclude that the main REY host phase of the mud is apatite. 相似文献
79.
Kinoshita D. Watanabe J. Fukushima H. Sekiguchi T. Yamamoto N. Abe S. 《Earth, Moon, and Planets》1997,77(3):265-269
A sequential imaging observation of the ion tail of Comet C/Hale-Bopp 1995O1 was carried out in February–March 1997 with a
wide-field CCD imaging camera using narrow band filters for two ion species; CO+ and H2O+ along with those for blue and red continuum. From the surface photometry of the ion tail of two species, we derived a relationship
between plasma density and distance from the nucleus. The local velocity of the ion flow as a function of the distance from
the nucleus was also estimated on the basis of some assumptions. We report preliminary results of our analysis, and discuss
some characteristics of cometary plasma and its interaction with interplanetary magnetic field (IMF).
May the source be with you!
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
80.
Two asteroids 2001 QQ199 and 2004 AE9 and two comets P/LINEAR-Catalina and P/LINEAR are found to be quasi-satellites of Jupiter
at present time. The Tisserand parameters of these four bodies lie between 2.3 and 2.5, which means two asteroids might be
Jupiter family comets and will show a cometary’s activity in the near future. 相似文献