Magnetic anomaly lineations from Late Jurassic to Early Cretaceous in the west-central Pacific Ocean   总被引：1，自引：0，他引：1  

Masao Nakanishi  Kensaku Tamaki  Kazuo Kobayashi 《Geophysical Journal International》1992,109(3):701-719

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The seasonally varying effect of the Tibetan Plateau on Northern Hemispheric blocking frequency and amplitude     

Kyung-Sook Yun  Ye-Won Seo  Kyung-Ja Ha  June-Yi Lee  Akio Kitoh 《Climate Dynamics》2016,47(7-8):2527-2541

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Application of a 3-D chemical fate prediction model (FATE3D) to predict dioxin concentrations in the Tokyo Bay     

Norihiro Kobayashi  Tomomi Eriguchi  Kisaburo Nakata  Shigeki Masunaga  Fumio Horiguchi  Junko Nakanishi 《Estuarine, Coastal and Shelf Science》2006,70(4):621

A 3-D chemical fate prediction model (FATE3D) was applied to predict the dioxin concentrations in the seawater of Tokyo Bay, Japan. The simulations were carried out for a period of one year (from September 2002 to August 2003). Parameters such as meteorological data, flow field conditions, concentrations and sinking rates of organic particulate matter, initial and boundary conditions, and loading fluxes and physico-chemical properties of dioxins were used as the model inputs.The simulation results compared favorably with the field measurements of dioxin concentrations in the bay for both the particulate and dissolved phases, indicating the validity and predictive capability of the model. Furthermore, the differences in the seasonal cycles and distributions between the particulate- and dissolved-phase dioxins in the bay were estimated from the simulation results.However, the particulate-phase dioxin concentrations in the bottom layers (+1 m from the bottom) were underestimated, probably because the resuspension process was not taken into account in the model. The improvement of the model's predictive capability, including the resuspension process, shall be the focus of our next study.  相似文献   

Occurrence of coprostanol, 24-ethylcoprostanol and 5α-stanols in the marine sediments     

Shin-ichi Teshima  Akio Kanazawa 《Journal of Oceanography》1978,34(3):85-92

The present study deals with the elucidation of sterol composition of the marine sediments in Kagoshima Bay. The identification of each sterol was performed by gas-liquid chromatography, Ag⁺ impregnated column chromatography, mass spectrometry, and nuclear magnetic resonance spectrometry. The sediment obtained near the estuary of River Koutsuki contained large portions of 5-stanols such as coprostanol and 24-ethylcoprostanol basides 5-stanols such as cholestanol, 24-methylcholestanol, and 24-ethylcholestanol in the sterol fraction. These 5-stanols in the marine sediment may be derived from the fecal contamination by domestic sewages.  相似文献   

Sensitivity of CFCs and Anthropogenic CO2 Uptake in a North Pacific GCM to Mixing Parameterization and Surface Forcing     

Akio Ishida  Kisaburo Nakata  Shigeaki Aoki  Hiroshi Kutsukake  Michio J. Kishi  Masahisa Kubota 《Journal of Oceanography》2001,57(4):433-450

Distributions and characteristics of water mass and chlorofluorocarbons (CFCs) in the North Pacific are investigated by using a General Circulation Model (GCM). The anthropogenic CO₂ uptake by the ocean is estimated with velocity fields derived from the GCM experiments. The sensitivity of the uptake to different diffusion parameterizations and different surface forcing used in the GCM is investigated by conducting the three GCM experiments; the diffusive processes are parameterized by horizontal and vertical eddy diffusion which is used in many previous models (RUN1), parameterized by isopycnal diffusion (RUN2), and isopycnal diffusion and perpetual winter forcing for surface temperature and salinity (RUN3). Realistic features for water masses and CFCs can be simulated by the isopycnal diffusion models. The horizontal and vertical diffusion model fails to simulate the salinity minimum and realistic penetration of CFCs into the ocean. The depth of the salinity minimum layer is better simulated under the winter forcing. The results suggest that both isopycnal parameterization and winter forcing are crucial for the model water masses and CFCs simulations. The oceanic uptake of anthropogenic CO₂ in RUN3 is about 19.8 GtC in 1990, which is larger by about 10% than that in RUN1 with horizontal and vertical diffusive parameterization. RUN3 well simulates the realistic water mass structure of the intermediate layer considered as a candidate of oceanic sink for anthropogenic CO₂. The results suggest that the previous models with horizontal and vertical diffusive parameterization may give the oceanic uptake of anthropogenic CO₂ underestimated. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

The transition zone chlorophyll front, a dynamic global feature defining migration and forage habitat for marine resources   总被引：2，自引：0，他引：2  

Jeffrey J. Polovina  Evan Howell  Donald R. Kobayashi  Michael P. Seki 《Progress in Oceanography》2001,49(1-4)

Pelagic ecosystem dynamics on all temporal scales may be driven by the dynamics of very specialized oceanic habitats. One such habitat is the basin-wide chlorophyll front located at the boundary between the low chlorophyll subtropical gyres and the high chlorophyll subarctic gyres. Global satellite maps of surface chlorophyll clearly show this feature in all oceans. In the North Pacific, the front is over 8000 km long and seasonally migrates north and south about 1000 km. In the winter this front is located at about 30–35°N latitude and in the summer at about 40–45°N. It is a zone of surface convergence where cool, vertically mixed, high chlorophyll, surface water on the north side sinks beneath warm, stratified, low chlorophyll water on the south side. Satellite telemetry data on movements of loggerhead turtles and detailed fisheries data for albacore tuna show that both apex predators travel along this front as they migrate across the North Pacific. The front is easily monitored with ocean color satellite remote sensing. A change in the position of the TZCF between 1997 and 1998 appears to have altered the spatial distribution of loggerhead turtles. The position and dynamics of the front varied substantially between the 1998 El Niño and the 1999 La Niña. For example, from May to July 1999 the transition zone chlorophyll front (TZCF) remained between about 35°N and 40°N latitude showing very little meandering, whereas in 1998, during the same period, the TZCF exhibited considerable meandering and greater monthly latitudinal movement. Catch rates for albacore were considerably higher in 1998 than in 1999, and we hypothesize that a meandering TZCF creates regions of convergence, which enhances the foraging habitat for apex predators along the front.  相似文献   

Induction of female‐to‐male sex change in a large protogynous fish,Choerodon schoenleinii          下载免费PDF全文

Taku Sato  Masato Kobayashi  Takayuki Takebe  Narisato Hirai  Koichi Okuzawa  Sayumi Sawaguchi  Takahiro Matsubara  Tomofumi Yamaguchi  Rihito Shinoda  Masahiko Koiso  Kazuhisa Teruya 《Marine Ecology》2018,39(1)

Most behavioral studies on hermaphroditic fishes have focused on small‐sized species, which are tractable for research. Although many species of large hermaphroditic fishes are important fishery resources, their proximate mechanisms (visual, chemical and/or behavioral cues) in the social regulation of sex change have not been determined. Determination of these would inform resource management and aquaculture. In order to get closer to understanding the proximate mechanisms underlying the social regulation of female‐to‐male sex change in large hermaphroditic fishes, this study reports situations that induced female‐to‐male sex change in black‐spot tuskfish, Choerodon schoenleinii, a species of large protogynous fish, in massive laboratory tanks. The situations differed in the possibility of male‐to‐female tactile contact and in the group sex ratio, enabling us to infer plausible proximate mechanisms underlying sex change induction. Tactile contact between individuals is suspected to be closely related to the incidence of female‐to‐male sex change in C. schoenleinii. Visual and chemical cues alone may be insufficient to inhibit such sex changes. Male‐to‐female tactile contact may have an important influence on female‐to‐male sex change, i.e., inhibition of this sex change, in this species. The effect of sex ratio of a social group on the incidence of sex change may be due to the relative frequency and intensity of male tactile contact with each female, which may vary with the number of females. In the absence of a dominant male, tactile contact among females may affect the incidence of sex change, as well as determine which individuals change sex.  相似文献   

Polarization Calibration of the <Emphasis Type="Italic">Chromospheric Lyman-Alpha SpectroPolarimeter</Emphasis> for a 0.1% Polarization Sensitivity in the VUV Range. Part II: In-Flight Calibration     

G. Giono  R. Ishikawa  N. Narukage  R. Kano  Y. Katsukawa  M. Kubo  S. Ishikawa  T. Bando  H. Hara  Y. Suematsu  A. Winebarger  K. Kobayashi  F. Auchère  J. Trujillo Bueno  S. Tsuneta  T. Shimizu  T. Sakao  J. Cirtain  P. Champey  A. Asensio Ramos  J. Štěpán  L. Belluzzi  R. Manso Sainz  B. De Pontieu  K. Ichimoto  M. Carlsson  R. Casini  M. Goto 《Solar physics》2017,292(4):57

The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket instrument designed to measure for the first time the linear polarization of the hydrogen Lyman-\({\upalpha }\) line (121.6 nm). The instrument was successfully launched on 3 September 2015 and observations were conducted at the solar disc center and close to the limb during the five-minutes flight. In this article, the disc center observations are used to provide an in-flight calibration of the instrument spurious polarization. The derived in-flight spurious polarization is consistent with the spurious polarization levels determined during the pre-flight calibration and a statistical analysis of the polarization fluctuations from solar origin is conducted to ensure a 0.014% precision on the spurious polarization. The combination of the pre-flight and the in-flight polarization calibrations provides a complete picture of the instrument response matrix, and a proper error transfer method is used to confirm the achieved polarization accuracy. As a result, the unprecedented 0.1% polarization accuracy of the instrument in the vacuum ultraviolet is ensured by the polarization calibration.  相似文献   

Origin of the metamorphosed clasts in the CV3 carbonaceous chondrite breccias of Graves Nunataks 06101, Vigarano,Roberts Massif 04143, and Yamato‐86009     

Kaori Jogo  Motoo Ito  Shigeru Wakita  Sachio Kobayashi  Jong Ik Lee 《Meteoritics & planetary science》2019,54(5):1133-1152

We observed metamorphosed clasts in the CV3 chondrite breccias Graves Nunataks 06101, Vigarano, Roberts Massif 04143, and Yamato‐86009. These clasts are coarse‐grained polymineralic rocks composed of Ca‐bearing ferroan olivine (Fa_24–40, up to 0.6 wt% CaO), diopside (Fs_7–12Wo_44–50), plagioclase (An_52–75), Cr‐spinel (Cr/[Cr + Al] = 0.4, Fe/[Fe + Mg] = 0.7), sulfide and rare grains of Fe‐Ni metal, phosphate, and Ca‐poor pyroxene (Fs₂₄Wo₄). Most clasts have triple junctions between silicate grains. The rare earth element (REE) abundances are high in diopside (REE ~3.80–13.83 × CI) and plagioclase (Eu ~12.31–14.67 × CI) but are low in olivine (REE ~0.01–1.44 × CI) and spinel (REE ~0.25–0.49 × CI). These REE abundances are different from those of metamorphosed chondrites, primitive achondrites, and achondrites, suggesting that the clasts are not fragments of these meteorites. Similar mineralogical characteristics of the clasts with those in the Mokoia and Yamato‐86009 breccias (Jogo et al. 2012 ) suggest that the clasts observed in this study would also form inside the CV3 chondrite parent body. Thermal modeling suggests that in order to reach the metamorphosed temperatures of the clasts of >800 °C, the clast parent body should have accreted by ~2.5–2.6 Ma after CAIs formation. The consistency of the accretion age of the clast parent body and the CV3 chondrule formation age suggests that the clasts and CV3 chondrites could be originated from the same parent body with a peak temperature of 800–1100 °C. If the body has a peak temperature of >1100 °C, the accretion age of the body becomes older than the CV3 chondrule formation age and multiple CV3 parent bodies are likely.  相似文献   

Application of spectral decomposition algorithm for mapping water quality in a turbid lake (Lake Kasumigaura,Japan) from Landsat TM data     

Youichi Oyama  Bunkei Matsushita  Takehiko Fukushima  Kazuo Matsushige  Akio Imai 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(1):73-85

The remote sensing of Case 2 water has been far less successful than that of Case 1 water, due mainly to the complex interactions among optically active substances (e.g., phytoplankton, suspended sediments, colored dissolved organic matter, and water) in the former. To address this problem, we developed a spectral decomposition algorithm (SDA), based on a spectral linear mixture modeling approach. Through a tank experiment, we found that the SDA-based models were superior to conventional empirical models (e.g. using single band, band ratio, or arithmetic calculation of band) for accurate estimates of water quality parameters. In this paper, we develop a method for applying the SDA to Landsat-5 TM data on Lake Kasumigaura, a eutrophic lake in Japan characterized by high concentrations of suspended sediment, for mapping chlorophyll-a (Chl-a) and non-phytoplankton suspended sediment (NPSS) distributions. The results show that the SDA-based estimation model can be obtained by a tank experiment. Moreover, by combining this estimation model with satellite-SRSs (standard reflectance spectra: i.e., spectral end-members) derived from bio-optical modeling, we can directly apply the model to a satellite image. The same SDA-based estimation model for Chl-a concentration was applied to two Landsat-5 TM images, one acquired in April 1994 and the other in February 2006. The average Chl-a estimation error between the two was 9.9%, a result that indicates the potential robustness of the SDA-based estimation model. The average estimation error of NPSS concentration from the 2006 Landsat-5 TM image was 15.9%. The key point for successfully applying the SDA-based estimation model to satellite data is the method used to obtain a suitable satellite-SRS for each end-member.  相似文献