Sea level variations around the Nansei Islands and the large meander in the Kuroshio south of central Japan     

Masaki Kawabe 《Journal of Oceanography》1980,36(4):227-235

The sea level difference between Naze and Nishinoomote and sea level anomalies (the residuals after removal of seasonal variations) around the Nansei Islands were examined in relation to the large meander in the Kuroshio south of central Japan. They are indices of surface velocity and geostrophic transport of the Kuroshio in the Tokara Strait and in the East China Sea, respectively. All of them were large during the meandering period, and each of them reached a maximum before or after the generation of the large meander in 1975. Thus the surface velocity and the geostrophic transport of the Kuroshio in the Tokara Strait and the East China Sea were large during the meandering period. The sea level difference between Naze and Nishinoomote (or Makurazaki) shows that the surface velocity and geostrophic transport in the Tokara Strait were significantly larger during the extinction stage in 1963 and during the generation stage in 1975 and were correlated with the position of the Kuroshio east of Kyûshû in 1974 and 1975 before the generation of the large meander.The surface velocity of the Kuroshio southeast of Yakushima (E-line) based on dynamic calculation referred to 1,000 db was weak during the meandering period, and was out of phase with the variation of surface velocity in the Tokara Strait monitored by tide gauge data. The analysis of GEK and hydrographic data shows that southwestward flow existed below 600 m in the slope region on the E-line and weakened during the meandering period. Thus, the out-of-phase variation in surface velocity mentioned above seems to be partly explained by the variation in velocity on the reference level at the E-line.  相似文献   

Coastal trapped waves in a two-layer ocean: Wave properties when the density interface intersects a sloping bottom     

Masaki Kawabe 《Journal of Oceanography》1982,38(3):115-124

Properties of coastal trapped waves when the pycnocline intersects a sloping bottom are studied using a two-layer model which has slopes in both layers. In this system there is an infinite discrete sequence of modes, and four different sorts of waves exist: the barotropic Kelvin wave, the upper shelf wave, the lower shelf wave and the internal Kelvin-type wave. They all propagate with the coast to their right in the Northern Hemisphere. The upper and lower shelf waves are due to the topographic-effect on the upper-layer and lower-layer slopes, respectively. Their motions are dominant in the respective layers being accompanied by significant interface elevations. The properties of the upper (lower) shelf wave are almost unaffected by the existence of a lower-layer (upper-layer) slope. The motion of the internal Kelvin-type wave is confined to the region around the line where the density interface intersects the bottom slope.The modes, except that with the fastest phase speed (the barotropic Kelvin wave), are assigned mode numbers in order of descending frequency. Characteristics of Mode 1 change with wavenumber; the upper shelf wave for small wavenumbers and the internal Kelvin-type wave for large wavenumbers (high frequencies). The higher modes of Mode 2 and above can be classified into the upper and lower shelf waves.  相似文献   

Sea level variations along the south coast of Japan and the large meander in the Kuroshio     

Masaki Kawabe 《Journal of Oceanography》1980,36(2):97-104

Sea level variations from 1974 through 1976 at 9 stations on the south coast of Japan (from west to east, Aburatsu, Tosa-shimizu, Muroto-misaki, Kushimoto, Uragami, Owase, Toba, Maisaka and Omaezaki) were analysed in relation to the large meander in the Kuroshio. From May to July in 1975, a small maximum in sea level variation was observed at every station west of Cape Shionomisaki from Aburatsu to Kushimoto. It propagated eastward along with the eastward propagation of a small meander in the Kuroshio until it reached Kushimoto, when the sea levels at Uragami and Owase started to rise sharply. This remarkable rise appeared at all stations in August when a large meander in the Kuroshio was established. The mean sea level at the stations east of Cape Shionomisaki from Uragami to Omaezaki rose by about 10 cm. The difference in sea level variations between the regions east and west of Cape Shionomisaki, which had been present before the rise, disappeared. A similar characteristic of sea level variation was also found in the generation stage of the large meander in 1959. The sea level variations along the south coast of Japan indicate that, prior to the generation of the large meander, the small meander in the Kuroshio was generated southeast of Kyushu and propagated eastward and that, just when this meander reached off Cape Shionomisaki, a large scale oceanic event covering over the whole region of the south coast of Japan occurred. This large scale event seems to be one of the necessary conditions for the generation of the large meander in the Kuroshio off Enshû-nada.  相似文献   

山东莒南地质公园发现小型兽脚类恐龙 足迹化石Minisauripus   总被引：2，自引：0，他引：2  

李日辉  Lockley Martin G  Matsukawa Masaki  刘明渭 《地质通报》2008,27(1):121-125

在山东省莒南地质公园内发现6个小型恐龙足迹化石,被归入足迹属Minisauripus。化石产于下白垩统大盛群田家楼组．时代为早白垩世巴列姆（Barremian）-阿普特期（Apdan）。5个较大,长约6cm,产于下部“主”层面上,其中4个组成2节行迹：1个较小,长约3cm,位于“主”层面30cm之上的上部层面上。山东Minisauripus的特征是：足迹个体小（长3．1～5．6cm,宽2．0～3．7cm）,三趾型,略不对称;足迹纵长,各趾近平行,趾垫较清晰;趾末端较钝,但爪迹较尖。Ⅲ趾比Ⅳ趾略长,而Ⅳ趾比Ⅱ趾略长且窄。此外,步幅较长,足长与步长之比约为10：1。与四川、韩国Minisau却淞不同之处是：足迹个体较大,长约是它们的2倍。继中国四川和韩国之后,山东是Minisau而淞在全球的第三个发现点。  相似文献   

Oil-generation kinetics for organic facies with Type-II and -IIS kerogen in the Menilite Shales of the Polish Carpathians     

M.D. Lewan  M.J. Kotarba  D. Wi?c?aw 《Geochimica et cosmochimica acta》2006,70(13):3351-3368

The Menilite Shales (Oligocene) of the Polish Carpathians are the source of low-sulfur oils in the thrust belt and some high-sulfur oils in the Carpathian Foredeep. These oil occurrences indicate that the high-sulfur oils in the Foredeep were generated and expelled before major thrusting and the low-sulfur oils in the thrust belt were generated and expelled during or after major thrusting. Two distinct organic facies have been observed in the Menilite Shales. One organic facies has a high clastic sediment input and contains Type-II kerogen. The other organic facies has a lower clastic sediment input and contains Type-IIS kerogen. Representative samples of both organic facies were used to determine kinetic parameters for immiscible oil generation by isothermal hydrous pyrolysis and S₂ generation by non-isothermal open-system pyrolysis. The derived kinetic parameters showed that timing of S₂ generation was not as different between the Type-IIS and -II kerogen based on open-system pyrolysis as compared with immiscible oil generation based on hydrous pyrolysis. Applying these kinetic parameters to a burial history in the Skole unit showed that some expelled oil would have been generated from the organic facies with Type-IIS kerogen before major thrusting with the hydrous-pyrolysis kinetic parameters but not with the open-system pyrolysis kinetic parameters. The inability of open-system pyrolysis to determine earlier petroleum generation from Type-IIS kerogen is attributed to the large polar-rich bitumen component in S₂ generation, rapid loss of sulfur free-radical initiators in the open system, and diminished radical selectivity and rate constant differences at higher temperatures. Hydrous-pyrolysis kinetic parameters are determined in the presence of water at lower temperatures in a closed system, which allows differentiation of bitumen and oil generation, interaction of free-radical initiators, greater radical selectivity, and more distinguishable rate constants as would occur during natural maturation. Kinetic parameters derived from hydrous pyrolysis show good correlations with one another (compensation effect) and kerogen organic-sulfur contents. These correlations allow for indirect determination of hydrous-pyrolysis kinetic parameters on the basis of the organic-sulfur mole fraction of an immature Type-II or -IIS kerogen.  相似文献   

T -distributed Random Fields: A Parametric Model for Heavy-tailedWell-log Data1     

Jo R?islien  Henning Omre 《Mathematical Geology》2006,38(7):821-849

Histograms of observations from spatial phenomena are often found to be more heavy-tailed than Gaussian distributions, which makes the Gaussian random field model unsuited. A T-distributed random field model with heavy-tailed marginal probability density functions is defined. The model is a generalization of the familiar Student-T distribution, and it may be given a Bayesian interpretation. The increased variability appears cross-realizations, contrary to in-realizations, since all realizations are Gaussian-like with varying variance between realizations. The T-distributed random field model is analytically tractable and the conditional model is developed, which provides algorithms for conditional simulation and prediction, so-called T-kriging. The model compares favourably with most previously defined random field models. The Gaussian random field model appears as a special, limiting case of the T-distributed random field model. The model is particularly useful whenever multiple, sparsely sampled realizations of the random field are available, and is clearly favourable to the Gaussian model in this case. The properties of the T-distributed random field model is demonstrated on well log observations from the Gullfaks field in the North Sea. The predictions correspond to traditional kriging predictions, while the associated prediction variances are more representative, as they are layer specific and include uncertainty caused by using variance estimates.  相似文献   

Estimation of the annual primary production of the lichen Cetrariella delisei in a glacier foreland in the High Arctic, Ny-Ålesund, Svalbard     

Masaki Uchida  Takayuki Nakatsubo  Hiroshi Kanda  Hiroshi Koizumi 《Polar research》2006,25(1):39-49

The fruticose lichen Cetrariella delisei is among the dominant lichen species in the deglaciated High Arctic areas of Svalbard. As part of a study of carbon cycling in the High Arctic, we aimed to estimate the primary production of lichen in a deglaciated area in Ny-Ålesund, Svalbard (79° N), by examining the effects of abiotic factors on the net photosynthesis ( Pn ) and dark respiration ( R ) rates of C. delisei . Experiments were conducted in the snow-free season of 2000 using an open-flow gas exchange system with an infrared gas analyser. Positive photosynthetic activities were observed on rainy days or soon after rainfall when the thallus water content was high, whereas photosynthetic activities dropped below the detectable limit on clear days because of the low thallus water content. Under a sufficiently high thallus water content and close to light saturation, Pn was nearly constant over a wide temperature range of 4–20 °C, while R increased with increasing temperature. We constructed a model for estimating the net primary production ( NPP ) of lichen based on the relationships between abiotic factors and the CO₂ exchange rate. The mean, minimum and maximum NPP values in the snow-free season, estimated using meteorological data obtained from 1995–2003, were 5.1, 1.0 and 8.4 g dry wt. m⁻² snow-free season⁻¹, respectively. These results suggest that NPP is highly variable and the contribution of lichen to carbon input is small compared with that of vascular plants and mosses in the study site.  相似文献   

Late Early Miocene lake deposits near Mauensee, central Switzerland: Fish fauna (otoliths, teeth), accompanying biota and palaeoecology     

Jürg Jost  Daniel K?lin  Tanja Schulz-Mirbach  Bettina Reichenbacher 《Eclogae Geologicae Helvetiae》2006,99(3):309-326

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韧性剪切变形对岩石地球化学行为的制约——以北阿尔金巴什考供韧性剪切带为例   总被引：6，自引：0，他引：6  

戚学祥李海兵  吴才来陈松永 《地质通报》2005,24(3):252-257

韧性剪切变形对岩石地球化学行为的制约一直是地质学家们探讨的课题。本文以构成北阿尔金红柳沟——拉配泉俯冲碰撞杂岩带与北阿尔金地块边界的巴什考供斜向逆冲型韧性剪切带为例，通过对韧性剪切带内花岗岩变形前后不同变形强度构造岩的地球化学组成进行对比，确定等比线斜率，探讨韧性变形对岩石体积和成分变异的影响。计算结果表明，在糜棱岩化过程中，糜棱岩化花岗岩体积亏损21％，花岗质糜棱岩体积亏损31％。质量平衡计算结果和等比线图表明，韧；陛剪切作用导致SiO2，流失量最大，A12O3、K2O及Ba、Rb、Sr等都有不同程度的丢失，显示出较强的活动性，MnO、P2O5、Sc位于等比线上或附近，表现出相对的稳定性。岩石中活动组分的变异是流体渗滤作用引起的，不活动组分的变异是体．积亏损造成的。  相似文献   

新时期我国区域经济地理学发展问题初探   总被引：4，自引：0，他引：4  

刘曙光 《地域研究与开发》2002,21(2):1-4

我国新时期的区域经济地理学在取得全面发展的同时，在理论体系，研究方法和实践领域等方面还需要进一步的发展，文章根据学习和实践区域经济地理学的体会，初步提出基础理论和应用理论，思维方法和技术方法等方面发展见解，并指出区域创新系统和国际经济技术合作等学科应注意拓展的重要实践领域，最后提出我国区域经济地理学科发展的建议。  相似文献