排序方式： 共有24条查询结果，搜索用时 15 毫秒
1.
Kazuo Abe Norihisa Nakagawa Katsuyuki Abo Mutsumi Tsujino 《Journal of Oceanography》2014,70(3):267-276
Distribution of silicic acid (Si(OH)4) in bottom water was investigated in the central Seto Inland Sea under stratified conditions in summer. Water samples were collected at 10 stations on April 24 and 25 and July 7 and 8, 2012. In July, stratification progressed, and a cold water mass (dome) of <20 °C appeared. In response to the cold dome, low oxygen content was observed in the bottom layer of the eastern part of Hiuchi-Nada. In this water mass site, apparent oxygen utilization values calculated from dissolved oxygen (DO) concentrations increased, coinciding with increase of Si(OH)4 concentrations from April to July. This suggests that increase of Si(OH)4 [dissolution of biogenic silica (diatom frustules)] was accompanied by DO consumption due to degradation of organic matter such as plankton soft tissue. These findings suggest that a bacterial degradation of the organic matrix that covers diatom frustules could accelerate the dissolution of biogenic silica in bottom water under stratified conditions. 相似文献
2.
Norihisa Usui Hiroyuki Tsujino Hideyuki Nakano Satoshi Matsumoto 《Journal of Oceanography》2013,69(6):647-670
This study investigates the long-term variability of the Kuroshio path south of Japan. Sensitivity experiments using a data-assimilative model suggest that the duration of the large meander (LM) strongly depends on the Kuroshio transport; specifically, low transport leads to a long duration of the LM. Actually, we find a good correlation between the duration of the past LMs and the Sverdrup transport estimated by a wind-driven linear baroclinic vorticity model. Then we explore favorable conditions for the LM and find a close relationship between the Kuroshio Extension (KE) state and the LM. That is, a precondition for the LM that the Kuroshio path on the Izu Ridge is fixed at a deep channel located around 34°N is achieved during a stable KE state. In addition, westward propagating signals with negative anomalies in the Kuroshio region and high sea-surface height (SSH) state east of Taiwan are key for generation of a small meander southeast of Kyushu that triggers a subsequent LM. The signals related to the above conditions change the upstream Kuroshio transport and velocity, which are consistent with features indicated by the former observational studies. Using reanalysis data, we construct long-time series of indices for the three conditions, which explain well the past LMs. The indices suggest that long-term non-LM states around 1970 and in the 1990s were attributed to a low-SSH state east of Taiwan and an unstable KE state, respectively. 相似文献
3.
Yasuyuki Tsujino Yasunari Shigeta Haruyoshi Maeda Toshifumi Komatsu Nao Kusuhashi 《Island Arc》2013,22(4):549-561
Discovery of Sirenites senticosus (Dittmar) in the upper part of the Sabudani Formation of the Kurosegawa Belt, Kito area, Tokushima Prefecture, Japan, establishes a late Early Carnian age for this part of the stratigraphic unit. Because S. senticosus was mainly distributed in the Tethyan region, its occurrence provides evidence that Late Triassic ammonoids of Japan had strong affinities with those of the Tethyan faunas. This finding clearly differs from the biogeographic distribution of contemporary bivalves in the region, which are referred to as the Kochigatani bivalve faunas, and show strong affinities to faunas of the Boreal region. 相似文献
4.
Hideyuki Nakano Hiroyuki Tsujino Mikitoshi Hirabara Tamaki Yasuda Tatsuo Motoi Masao Ishii Goro Yamanaka 《Journal of Oceanography》2011,67(6):765-783
The uptake mechanism of anthropogenic CO2 in the Kuroshio Extension is examined by a Lagrangian approach using a biogeochemical model embedded in an ocean general circulation model. It is found that the uptake of anthropogenic CO2 is caused mainly by the increase of pCO2 dependency of seawater on temperature, which is caused by greater dissolved inorganic carbon concentration in the modern state than in the pre-industrial state. In contrast with the view of previous studies, the effect of the vertical entrainment, which brings waters that last contacted the atmosphere with the past lower CO2 concentration, is comparatively small. Winter uptake of anthropogenic CO2 increases with the rise of the atmospheric CO2 level, while summer uptake is relatively stable, resulting in a larger seasonal cycle of the uptake. This increase is significant, especially in the Kuroshio Extension region. It is newly suggested that this increase in the Kuroshio Extension region is largely caused by the combined effects of the increased pCO2 dependency of the sea water on the temperature and the seasonal difference in cooling. 相似文献
5.
Sakamoto Kei Tsujino Hiroyuki Nakano Hideyuki Urakawa Shogo Toyoda Takahiro Hirose Nariaki Usui Norihisa Yamanaka Goro 《Ocean Dynamics》2019,69(10):1181-1202
Ocean Dynamics - In order to expand the coastal ocean monitoring and forecasting system of the Japan Meteorological Agency from the Seto Inland Sea to the entire coastal seas of Japan, a 2-km... 相似文献
6.
A dataset of continental river discharge based on JRA-55 for use in a global ocean circulation model
Tatsuo Suzuki Dai Yamazaki Hiroyuki Tsujino Yoshiki Komuro Hideyuki Nakano Shogo Urakawa 《Journal of Oceanography》2018,74(4):421-429
A dataset of historical river discharge into oceans was created using the CaMa-Flood global river routing model and adjusted runoff from the land component of JRA-55. The major rivers were well resolved with a 0.25° horizontal resolution. The total runoff on each drainage basin exhibits a distinctive bias on decadal time scales. The input runoff data were modified using 5-year low-pass-filtered multiplicative factors to fit the annual mean climatology and decadal variations in the reference dataset. The model incorporated data from 1958 to 2016. The yearly and seasonal variations of the major rivers are well represented by the model. 相似文献
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The mechanism governing the mean state and the seasonal variation of the transports through the straits of the Japan Sea is
studied using a newly presented, simple analytical model and a basin scale general circulation model (GCM). The GCM reproduces
the transports through the straits of the Japan Sea realistically owing to its fine horizontal resolution of about 20 km and
realistic topography. A series of experiments conducted by changing surface forcing shows that the annual mean wind-driven
circulation in the North Pacific Ocean is most responsible for the formation of the mean transports. It is also found that
the seasonal variation of the alongshore component of monsoonal wind stress over the North Pacific basin, especially that
over the Okhotsk Sea, is responsible for the seasonal variation of the transports. The simple analytical model can explain
these simulated features very well. The physical concept of this model is based on the formation of the around-island circulation
through the adjustment of coastally trapped waves and Rossby waves and geostrophic control at the narrow straits. It solves
the sea surface heights (SSHs) at the edge of each strait and the transport through it. The value of the line integral of
the SSH along the island is determined by the baroclinic Rossby waves approaching the island from the east and the alongshore
wind stress around the island. The basin scale seasonal variation of SSH along the coast induced by the variation of the alongshore
monsoonal wind stress can also be incorporated into this model by giving the SSH anomaly at the northeastern point of the
Soya Strait. Thus, it is suggested that both the mean state and the seasonal variation are caused mainly by wind stress forcing.
Minor modification by the seasonal heat flux forcing brings the amplitude and the phase of the seasonal variation closer to
the observed values. 相似文献
10.
Short-range prediction experiments of the Kuroshio path variabilities south of Japan 总被引：1，自引：0，他引：1
Assimilation and prediction experiments of the Kuroshio path variability south of Japan were conducted to investigate the
predictability of the Kuroshio path. The assimilation and prediction system is composed of an eddy-resolving model and a three-dimensional
variational analysis scheme with vertical coupled temperature–salinity empirical orthogonal function modes. The sea surface
height (SSH) variability and the variations of the Kuroshio path of the assimilation fields are in good agreement with those
observed. The results of the assimilation are then used as the initial conditions for 138 cases of 90-day prediction experiments
conducted from 1993 to 2004. The predictive limit of our system is assessed by the SSH anomaly in the assimilation field and
is found to be around 40–60 days, which is much longer than that of the persistence. The prediction results show good performance
in the transition stage from a straight to a meandering path. For example, a large meandering event that occurred in August
2004 is successfully predicted in a 2-month forecast. Two types of failure cases are investigated. One is a case where the
eastward propagation speed of the meander is faster than a real state. The dynamical response of the model to the assimilation
revealed that an initial shock, caused by the dynamically unbalanced initial condition, induces the fast eastward propagation
of the meander. The other case exhibits an unrealistic meander. In this case, a cold anomaly at an intermediate layer in the
initial condition grows rapidly and results in the unrealistic meander. This implies that the Kuroshio path south of Japan
has a chaotic nature. These facts revealed by the failure cases give us some insight for improving the predictive skill of
the Kuroshio path variability. 相似文献