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1.
Shinko Aoki 《Celestial Mechanics and Dynamical Astronomy》1987,42(1-4):309-354
A relation between the Celestial Reference System (CRS) and the Terrestrial Reference System is established theoretically by solving the equations of motion of a rigid Earth under the influence of the Sun and the Moon up to the second order perturbation. The solutions include not only nutation including Oppolzer terms but also the right ascension of the dynamical departure point (DP), as well as the wobble matrix.We have found that the kinematical definition of the Non-Rotating Origin NRO (for which our term is DP) given by Capitaine, Guinot and Souchay (1987) is not entirely equivalent to that included in the solutions of the equations of motion but shows perturbation, in particular when this is taken on the instantaneous equator. Besides this serious fault, we feel little merit in taking the DP as reference: (1) Unnecessary spurious mixed secular terms appear which come from the geometrical configuration that the DP leaves far and far from the ecliptic. (2) the DP moves secularly as well as oscillating with respect to space; this literally contradicts the term NRO, or is at least misleading. (3) It does not free us from the precession uncertainty to adopt DP as reference, since we cannot avoid virtual proper motions in terms of the current CRS. (4) No terms ignored hitherto are introduced, even if we take the DP properly chosen, i.e., on the equator of the celestial ephemeris pole. The transformation is only mathematical. There is no sufficient reason to take it instead of the equinox, which is observable in principle, as reference at the cost of the labor of changing all the textbooks, ephemerides, data and computer software now existing. 相似文献
2.
Toru?Iwata Keiko?Yoshikawa Katsutoshi?Nishimura Yoshihisa?Higuchi Takao?Yamashita Shigeru?Kato Eiji?OhtakiEmail author 《Journal of Oceanography》2004,60(6):995-1000
The measurements of the vertical transport of CO2 were carried out over the Sea of Japan using the specially designed pier of Kyoto University on September 20 to 22, 2000. CO2 fluxes were measured by the eddy correlation and aerodynamic techniques. Both techniques showed comparable CO2 fluxes during sea breeze conditions: −0.001 to −0.08 mg m−2s−1 with the mean of −0.05 mg m−2s−1. This means that the measuring site satisfies the fetch requirement for meteorological observations under sea breeze conditions. Moreover, the eddy diffusivity coefficient used in the aerodynamic technique is found to be consistent with the coefficient used in the eddy correlation technique. The present result leads us to conclude that the aerodynamic technique may be applicable to underway CO2 flux measurements over the ocean and may be used in place of the bulk technique. The important point is the need to maintain a measuring accuracy of CO2 concentration difference of the order of 0.1 ppmv on the research vessels or the buoys. 相似文献
3.
Large amorphous particles (Nuta) observed in coastal areas after phytoplankton blooms and red tide outbreaks were collected by Nuta traps. These particles are always thickly attached to mooring ropes and/or fishing nets. From the decomposition experiments of Nuta and the sinking particles, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) regenerations were active in Nuta, but were not active in sinking particles. In Nuta, regeneration abundances during 10 days were 567 g-N/mg of initial particulate organic nitrogen (PON), and 583 -P/mg of initial particulate phosphorus (PP), respectively. Thus DIP was more regenerated from Nuta than DIN. Ten days integral regeneration abundances of DIN and DIP from Nuta were estimated to be 36% and 79% of in situ DIN and DIP standing stocks, respectively. Nuta contributes an important role of nutrient regeneration particularly DIN, in coastal water. Carbon and nitrogen stable isotope ratios of suspended particles, sinking particles and Nuta indicated that these three different type of particles were almost the same origin, and thus Nuta in the coastal water should be made from phytoplankton debris. 相似文献
4.
Seasonal and Spatial Variations of Iceberg Drift off Dronning Maud Land, Antarctica, Detected by Satellite Scatterometers 总被引:1,自引:0,他引:1
Shigeru Aoki 《Journal of Oceanography》2003,59(5):629-635
Seasonal and spatial variations of iceberg drift were studied using continuous satellite scatterometer images off Dronning
Maud Land, East Antarctica. Generally, iceberg drift speed showed a westward increase to the Greenwich Meridian. Seasonal
variations of the drift speed were high in autumn—early winter and low in spring, and their magnitudes also increased westward.
Seasonal variations of the drift speed were significantly correlated with variations of sea levels at Syowa and Mawson Stations,
and hence qualitatively consistent with geostrophic current variations. Thus, the scatterometer data are demonstrated to be
useful in monitoring iceberg trajectory and oceanic current variations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Ichiro Ishikawa Shigeaki Aoki Ryo Furue Nobuo Suginohara 《Journal of Oceanography》1996,52(5):617-632
In recognition that similarity in the density balance leads to resemblance in circulation between the two-dimensional non-rotating and three-dimensional rotating systems which have similar density stratification, we investigate convection induced by cooling at one side wall and heating at the sea surface by using a two-dimensional non-rotating model as idealized representation for the deep Pacific circulation. In the model, various vertical profiles are taken for the side wall cooling, which are assumed to correspond to the density structure of the Anatarctic Circumpolar Current. In a small diffusivity range, two important features are found to be robust against change in the vertical profile of the side wall cooling. One is that the density stratification is horizontally almost uniform. The other is that the balance in the density equation between the vertical advection and the vertical diffusion holds in the interior. Consequently, the vertical density balance, together with the equation of continuity, determines the circulation pattern for the prescribed vertical profile of the side wall cooling. The multi-layered meridional flow, which is expected to exist in the deep Pacific, is shown to form for certain vertical profiles of the side wall cooling. 相似文献
6.
7.
The Princeton Ocean Model with realistic bottom topography has been used to investigate the summer temperature decrease in
the past 25 years in Fukuoka Bay. The vertical mixing of the model is expressed by a scheme that effectively includes the
influences of interannual variations of tidal currents and wind. The results show that the historical temperature decrease
in summer has been caused by tidal currents and wind weakening in the past 25 years in Fukuoka Bay. The weakening of tidal
currents and wind gives rise to weakening of the vertical mixing, and to enhancement of the estuarine circulation in the bay.
The enhancement of the estuarine circulation activates the inflow of open-ocean water toward Fukuoka Bay. Coastal water in
summer has therefore tended to be colder and more saline in the past 25 years. This interannual variation in coastal waters
is called “open-oceanization” in this study. On the basis of the numerical model, it is anticipated that the temperature will
decrease by 0.2°C in the next 25 years in Fukuoka Bay if the tide and wind weaken persistently as in the present bay. 相似文献
8.
9.
The physical and chemical variability of the water column at subtidal station of an estuary in the Seto Inland Sea, Japan,
was studied over a 24-hour period during a spring tide (tidal range ca. 2 m) in May 1995. Surface water and several depths through the water column were monitored every one and two hours, respectively.
At each occasion, water temperature, salinity and dissolved oxygen concentration were measured and water samples were collected
for the determination of nutrients and suspended particulate matter (SPM). Disruptive changes in the physical and chemical
characteristics of the water was produced by the tidal cycle and the mixing of water masses of different origin. These changes
were highly significant both spatially and temporally, yet with varying effects on physical parameters, nutrients and the
different components of SPM. Significant differences in nutrient concentrations were also observed when the data-set was divided
into ebb and flood components, irrespective of the depth. Nitrate and nitrite rose to 1.8 times higher during the flood. Spatial
differences of SPM were less marked than those of nutrients, only particulate organic carbon (POC) being significantly higher
at the surface than in the intermediate and the lower layer. Both POC and pheopigment concentrations increased markedly through
the water column, being highest shortly before the lower low tide. In contrast, suspended solid (SS) content increased sharply
after the lower low tide (>40 mg l−1) and this coincided with a marked decrease of the C/SS content (<20 mg g−1). The lagtime between POC and SS tidal transport was caused by particle resuspension from the exposed intertidal sediments
as the tidal level rose, and particle transport selection in relation to the tidal state.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Preparation of a New Geological Survey of Japan Geochemical Reference Material: Coral JCp-1 总被引:2,自引:0,他引:2
Takashi Okai Atsushi Suzuki Hodaka Kawahata Shigeru Terashima Noboru Imai 《Geostandards and Geoanalytical Research》2002,26(1):95-99
A new geochemical reference material, coral Porites sp. JCp-1 has been prepared by the Geological Survey of Japan (GSJ). Provisional values for twenty one major, minor and trace elements are presented. The homogeneity tests showed that all elements studied are considered to be homogeneously distributed. 相似文献