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201.
The evolution of an isolated meso-scale eddy near a coast is studied numerically. In particular, it is found that the translation speed of the adjusted eddy is estimated well by the mutual induction mechanism adapted to a rotating stratified fluid. The nonlinear Kelvin wave excited during the adjustment process is also discussed in connection with the Kyucho, the sudden warming of coastal waters associated with swift currents. 相似文献
202.
Temporal variability of winter mixed layer in the mid-to high-latitude North Pacific 总被引:1,自引:2,他引:1
Temperature and salinity data from 2001 through 2005 from Argo profiling floats have been analyzed to examine the time evolution
of the mixed layer depth (MLD) and density in the late fall to early spring in mid to high latitudes of the North Pacific.
To examine MLD variations on various time scales from several days to seasonal, relatively small criteria (0.03 kg m−3 in density and 0.2°C in temperature) are used to determine MLD. Our analysis emphasizes that maximum MLD in some regions
occurs much earlier than expected. We also observe systematic differences in timing between maximum mixed layer depth and
density. Specifically, in the formation regions of the Subtropical and Central Mode Waters and in the Bering Sea, where the
winter mixed layer is deep, MLD reaches its maximum in late winter (February and March), as expected. In the eastern subarctic
North Pacific, however, the shallow, strong, permanent halocline prevents the mixed layer from deepening after early January,
resulting in a range of timings of maximum MLD between January and April. In the southern subtropics from 20° to 30°N, where
the winter mixed layer is relatively shallow, MLD reaches a maximum even earlier in December–January. In each region, MLD
fluctuates on short time scales as it increases from late fall through early winter. Corresponding to this short-term variation,
maximum MLD almost always occurs 0 to 100 days earlier than maximum mixed layer density in all regions. 相似文献
203.
The present study developed a high-quality climatological dataset for the Indian Ocean - the Indian Ocean HydroBase (IOHB) - from a combined dataset including the World Ocean Database 1998 version 2 (WOD98v2). Methods are similar to those used by previous studies for other oceans. Japanese data for the IOHB originated from the Japanese datasets MIRC (Marine Information Research Center) Ocean Dataset 2001 and Far Seas Collection; these datasets contain more Japanese observations than WOD98v2. Water mass properties in the IOHB climatology are consistent with previous studies. Seasonal patterns of properties near the sea surface are well reproduced, and deep-layer properties are consistent with the Reid-Mantyla climatology that is derived from high-quality observations. The isopycnal climatology of the IOHB differs from the World Ocean Atlas 2001 (WOA01) along the fronts associated with the Antarctic Circumpolar Current (ACC). The WOA01 shows a warm and saline intermediate water intrusion from South Africa to the east along the northern edge of the front. Such an intrusion is absent in IOHB where less saline intermediate water extends continuously northward from the southern ocean. The WOA01 shows a continuous belt of low potential vorticity along the ACC. This feature is less distinct in the IOHB climatology and in the Reid-Mantyla climatology. The IOHB consists of a 1° × 1° gridded climatology and the datasets of raw and quality-controlled hydrographic stations. The latter is valuable for quality control of the Argo float salinity data as climatological reference. These datasets are available freely via the Internet. 相似文献
204.
Takashi Yabuki Toshio Suga Kimio Hanawa Koji Matsuoka Hiroshi Kiwada Tomowo Watanabe 《Journal of Oceanography》2006,62(5):649-655
It has been inferred that the Prydz Bay region is one of the source regions of Antarctic Bottom Water (AABW) based on rather
indirect evidence. In order to examine this inference, we investigate the hydrographic condition of the bay based mainly on
XCTD data obtained during the Japanese Whale Research Program in the Antarctic (JARPA). The JARPA hydrographic data reveal
Circumpolar Deep Water (CDW), which is a salty, warm water mass approaching the shelf break, and capture Modified CDW (MCDW)
intruding into the shelf water. AABW production requires mixing of CDW and cold shelf water saltier than 34.6 psu, which is
a saltier type of Low Salinity Shelf Water (LSSW). Saltier LSSW is observed near the bottom over the shelf, being mixed with
MCDW. We further identify saltier LSSW near the shelf break. This saltier LSSW appears close enough to unmodified CDW to be
mixed with it over the continental slope, indicating a possible source of AABW in Prydz Bay. 相似文献
205.
Analyses of gallium content were made by the fluorometric method on 57 samples of seaweeds which were composed of 30 species. As the result of it, the gallium content was found ranging from 0.02 to 0.64g g–1 and the average was 0.14g g–1 in the dried seaweeds.Generally, the gallium content in seaweeds had a close relationship to the aluminium and iron contents. The average weight ratio of Ga/Al was 3.8×10–4 and one of Ga/Fe was 4.0×10–4. The average Ga/Al weight ratio (3.8×10–4) was very similar to that reported for shallow-water deposits (2.1×10–4), but was definitely lower than that in sea water (1.5×10–2). 相似文献
206.
Toshio Yamagata 《Journal of Oceanography》1974,30(6):282-288
The formation of the spun up region by the withdrawal of water from a watergate located in the eastern boundary in a homogeneous ocean on a beta-plane at low Rossby number is presented. The spun up region penetrates only westward from the Watergate because of the special character of the generated Rossby waves. The growth rate and the final longitudinal length of the spun up region in the dissipative system is much affected by the watergate scale in the north-south direction.The relation with the experiment ofLong (1952) and the geophysical application are presented. 相似文献
207.
Five heat flow measurements were made in the Asiatic Mediterranean Sea; two in the Celebes Sea and three in the Sulu Sea. The mean of all five values of 2.0 cal/cm2 sec is significantly greater than the over-all mean heat flow value for the oceans and is close to the mean value for marginal seas. The measurement indicate that there may be a difference in the flow of heat through the two seas.Contribution of the Scripps Institution of Oceanography, new series. 相似文献
208.
The contents of plutonium isotopes (239Pu and238Pu), thorium isotopes (232Th,230Th and228Th) and protactinium-231 in sea water collected in the North Pacific, the East China Sea and the Japan Sea were determined. These nuclides were sequentially analyzed byα-ray spectrometry after separating them mainly with solvent extraction technique. The contents of239Pu in surface sea water ranged from 0.6 to 1.6 pCi/10001,238Pu/239Pu activity ratios being 0.2~0.7. The228Th/232Th activity ratios for the North Pacific waters varied between 7.6 and 30, whereas the sample from the East China Sea showed the very high value, 65. The contents of231Pa are less than 6 percent of that in equilibrium with its parent235U. Furthermore, the analysis of plutonium isotopes in recent coral from Yoron Island was carried out and it was confirmed that plutonium isotopes have concentrated in recent coral with the concentration factor of about 1~2×103. 相似文献
209.
Kenji Kashiwaya Toshio Nakamura Nobuki Takamatsu Hideo Sakai Manabu Nakamura Takayoshi Kawai 《Journal of Paleolimnology》1997,18(3):293-297
Physical and chemical properties of two 100 m sediment cores (BDP-93-1, 93-2) obtained from the Buguldeika saddle of Lake Baikal in the eastern Siberia and a 14C-based age scale for the core show that the core bottom is about 400000 years ago and that the changes in the sedimentological environment of the area during the interval were that comparatively coarse and high C/N ratio sediments accumulated in the lake during interglacial periods, and fine material and low C/N ratio during glacial periods. The tentative age scale suggests that the first excursion in the earth's magnetic field at about 26 m (BDP-93-1 and 93-2) from the sediment surface corresponds to the Blake event. Statistical analyses of the data-sets for the some properties show that the fluctuations have distinct periods; 20000 years, 40000 years and 100000 years, that are related to the Milankovitch parameters and support that the tentative age scale is approximately acceptable. 相似文献
210.
Yasumasa Ogawa Naotatsu Shikazono Daizo Ishiyama Hinako Sato Toshio Mizuta Takanori Nakano 《Mineralium Deposita》2007,42(3):219-233
The Sr, Ba, and rare earth elements (REEs) concentrations and Sr isotopic composition of anhydrite and gypsum have been determined
for samples from the Matsumine, Shakanai, and Hanaoka Kuroko-type massive sulfide–sulfate deposits of northern Japan to evaluate
the mechanisms of sekko (anhydrite and gypsum) ore formation. The Sr isotopic compositions of the samples fall in the range
of 0.7077–0.7087, intermediate between that for middle Miocene (13–15 Ma) seawater (0.7088) (Peterman et al., Geochim Cosmochim
Acta, 34:105–120, 1970) and that for country rocks (e.g., 0.7030–0.7050) (Shuto, Assn Geol Collab Japan Monograph 18:91–105, 1974). The Kuroko anhydrite samples exhibit two types of chondrite-normalized REE patterns: one with a decrease from light REEs
(LREEs) to heavy REEs (HREEs) (type I), and another with a LREE-depleted pattern (type II).
Based on the Sr content and isotopic ratio (assuming an Sr/Ca (mM/M) of 8.7 for seawater), anhydrite is considered to have
formed by mixing of preheated seawater with a hydrothermal solution of Sr/Ca (mM/M) = ca. 0.59–1.36 under the condition in
which the partition coefficient (Kd) ranges between ca. 0.5 and 0.7. This results in the formation of anhydrite with higher
Sr content with an Sr isotopic value close to that of seawater under seawater-dominant conditions.
Larger crystals of type II anhydrite are partly replaced by smaller ones, indicating that anhydrite dissolution and recrystallization
occurred after or during the formation of sekko ore. Gypsum, which partially replaces anhydrite in the Kuroko deposits, also
exhibits two distinct chondrite-normalized REE patterns. Because LREEs are likely to be more readily mobilized during dissolution
and recrystallization, it is hypothesized that LREEs are leached from type I anhydrite, resulting in the formation of type
II anhydrite with LREE-depleted profiles. 相似文献