Fifteen years progress of the TRITON array in the Western Pacific and Eastern Indian Oceans     

Kentaro Ando  Yoshifumi Kuroda  Yosuke Fujii  Tatsuya Fukuda  Takuya Hasegawa  Takanori Horii  Yasuhisa Ishihara  Yuji Kashino  Yukio Masumoto  Keisuke Mizuno  Motoki Nagura  Iwao Ueki 《Journal of Oceanography》2017,73(4):403-426

The Triangle Trans‐Ocean Buoy Network (TRITON) project by the Japan Agency for Marine-Earth Science and Technology began with deployment in the western tropical Pacific Ocean in 1998 and has shifted to steady, long-term observations since 1999. After on-site inter-comparison with the Autonomous Temperature Line Acquisition System mooring system of the Tropical Atmosphere and Ocean (TAO) array by the National Oceanic and Atmospheric Administration, the TRITON array became the international TAO/TRITON array in 2000 as a key component of the Global Ocean and Climate Observing Systems. The TAO/TRITON array took over from the TAO array, which was developed during the Tropical Ocean and Global Atmosphere program (1985–1994), and replaced the western part of TAO with new additional real-time measurements of salinity and ocean currents. In 2001, two TRITON moorings were deployed in the eastern Indian Ocean for capturing the eastern pole of the Indian Ocean Dipole. From this initiative, the Indian Ocean Observing System (IndOOS) was designed, and the Indian Ocean mooring array (Research Moored Array for Africa–Asian–Australian Monsoon Analysis and Prediction) was developed as a key component of IndOOS. In this paper, 15 years of progress in the TRITON project in the western Pacific and eastern Indian Oceans is reviewed with regards to scientific outcomes, technological development, and collaborations with international and domestic partners. Future directions for sustainable observation in the Pacific and Indian Oceans are also discussed.  相似文献   

Seasonal variations of the Hawaiian Lee Countercurrent induced by the meridional migration of the trade winds   总被引：1，自引：0，他引：1  

Hideharu Sasaki  Shang-Ping Xie  Bunmei Taguchi  Masami Nonaka  Yukio Masumoto 《Ocean Dynamics》2010,60(3):705-715

Seasonal variations of the Hawaiian Lee Countercurrent (HLCC) are investigated using satellite observations of sea surface height and wind stress as well as eddy-resolving ocean model simulations. The HLCC is strong from summer to winter and weak in spring between the dateline and the Hawaiian Islands. In response to the seasonal migration of the northeast trade winds in the meridional direction, the wind curl dipole lee of Hawaii varies in strength, exciting westward-propagating Rossby waves. The analyses of both observations and simulations show that the propagation of Rossby waves south of the HLCC, driven by the southern pole of the wind curl dipole in the lee of the islands, contributes the most to the seasonal variations of the HLCC. Unlike the wind-driven seasonal variations, our analysis suggests that other mechanisms such as mode water intrusion or air–sea interaction may cause the interannual variations of the HLCC.  相似文献   

Variation of the partial pressure of CO2 in surface water from Kuroshio to Oyashio and the relation between environmental factors and the partial pressure at 144°E off Sanriku, northwestern North Pacific in May, 1997     

Katsuyuki Sasaki  Tsuneo Ono  Katsuhisa Tanaka  Kiyoshi Kawasaki  Hiroshi Saito 《Journal of Oceanography》1998,54(5):593-603

Partial pressure of CO₂ in surface sea water (pCO₂) was measured continuously off Sanriku in May, 1997 by a new pCO₂ measurement system. We have examined the relation of pCO₂ to physical factors such as temperature, salinity and density, chemical and biological factors such as nutrients and carbonate system and chlorophylla. In the Kuroshio region pCO₂ was not correlated to physical, chemical and biological factors in the range of 260 to 290 μatom. In transition water (Tr1) between Kuroshio and the Oyashio second branch, pCO₂ was weakly correlated to physical factors and strongly correlated to nutrients. In transition water (Tr2) between the Oyashio first and second branches, pCO₂ was highly correlated to temperature (SD: 10.9 μatom) and salinity (SD: 8.6 μatom) and also to nutrients. In transition water (Tr1+Tr2), pCO₂ was highly multivariately correlated to temperature (T), salinity (S), chlorophylla (CH) (or nitrate+nitrite (N)) as follows, pCO₂(μatom)= 10.8×T(°C)+27.7×S+2.57CH(μg/1) −769, R²= 0.86, SD = 20.9, or pCO₂(μatom)= 3.9×T(°C)+25.5×S+16.0NO₃(μM) −686, R²= 0.99, SD = 6.4. Moreover, pCO₂ was predicted by only two factors, one physical (S) and the other chemical/biological (N) as follows: pCO₂ (μatom)=32.8×S+19.4N−908, R²=0.97, SD=8.4. The pH measured at 25°C was well correlated with normalized pCO₂ at a fixed temperature. In the Oyashio region pCO₂ was decreased to 160 μatom, probably because of spring bloom, but was not correlated linearly to chlorophylla. The results obtained showed the possibility of estimating pCO₂ of the Oyashio and transition regions in May by satellite remote sensing of SST, but the problem of estimation of pCO₂ in Kuroshio water remains to be solved.  相似文献   

Analytic black hole perturbation approach     

Misao Sasaki 《Journal of Astrophysics and Astronomy》1999,20(3-4):281-289

In this talk, I review an analytic method for calculating gravitational radiation from a small mass particle orbiting a massive black hole. This method allows a systematic evalutation of the gravitational radiation to a very high order in post-Newtonian expansion, hence gives us useful information on the evolution of coalescing compact binary stars.  相似文献   

Multiple‐indicator study of groundwater flow and chemistry and the impacts of river and paddy water on groundwater in the alluvial fan of the Tedori River,Japan          下载免费PDF全文

Yumi Iwasaki Yoshioka  Kimihito Nakamura  Takanori Nakano  Haruhiko Horino  Ki‐Cheol Shin  Satoko Hashimoto  Shigeto Kawashima 《水文研究》2016,30(16):2804-2816

To investigate the source, flow paths, and chemistry of rich resources of high‐quality, shallow groundwater in the alluvial fan between the Tedori and Sai rivers in central Japan, we analysed stable isotope ratios of H, O, and Sr and concentrations of major dissolved ions and trace elements in groundwater, river water, and paddy water. The ⁸⁷Sr/⁸⁶Sr ratios of the groundwater are related to near‐surface geology: groundwater in sediment from the Tedori River has high ⁸⁷Sr/⁸⁶Sr ratios (>0.711), whereas that from the Sai River in the north of the fan has low ⁸⁷Sr/⁸⁶Sr ratios (<0.711). δ²H and δ¹⁸O values and ⁸⁷Sr/⁸⁶Sr ratios indicate that groundwater in the central and southern fans is recharged by the Tedori River, whereas recharge in the north is from the Sai River. Mg²⁺, Ca²⁺, Sr²⁺, HCO₃^?, and SO₄^2? concentrations and δ²H and δ¹⁸O values in the groundwater are high in the central fan and, except for the northern area, tend to increase with distance from the Tedori River. There are linear relationships between ⁸⁷Sr/⁸⁶Sr ratio and the reciprocal concentrations of Sr²⁺, Mg²⁺, and Ca²⁺. These geochemical characteristics suggest that as groundwater recharged from the Tedori River flows towards the central fan, it mixes with waters derived from precipitation and paddy water that have become enriched in these components during downward infiltration. These results are consistent with our hydrological analysis and numerical simulation of groundwater flow, thus verifying the validity of the model we used in our simulation of groundwater flow. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Three-dimensional analysis of groundwater flow in neogene rocks at the Rokkasho low-level radioactive waste disposal center, Japan     

Tai Sasaki  Naro Hashimoto  Takayuki Nakato  Tomonari Shiraishi  Kazuaki Yajima  Tomoyuki Hishiya 《Engineering Geology》1998,49(3-4):337-343

As a preliminary step for predicting groundwater flow in a plateau 30–50 m above sea level, a model for three-dimensional analysis of groundwater flow was formulated and its validity was verified. The plateau consists of Neogene sedimentary rocks and a Quaternary deposit. Most of the groundwater originates in precipitation, with the groundwater table lying in the Quaternary deposit. Steady-state analysis was conducted by using the finite element method. The results of pore-water pressure measurement and water examination were useful in verifying the validity of the model. In constructing the model, reducing the hydraulic conductivity according to the depth on the basis of the results of the actual measurement was important.  相似文献   

Three-year assessment of particulate organic carbon fluxes in Amundsen Gulf (Beaufort Sea): Satellite observations and sediment trap measurements     

Alexandre Forest  Simon Bélanger  Makoto Sampei  Hiroshi Sasaki  Catherine Lalande  Louis Fortier 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(1):125-142

Surface concentrations and vertical fluxes of particulate organic carbon (POC) were assessed in the Amundsen Gulf (southeastern Beaufort Sea, Arctic Ocean) over the years 2004 to 2006 by using ocean color remote-sensing imagery and sequential sediment traps moored over the ca. 400 m isobath. Environmental conditions (sea ice, wind) and oceanographic variables (temperature, salinity, fluorescence and currents) were investigated to explain the variability of POC data. Annual downward POC fluxes in 2004, 2005 and 2006 cumulated, respectively, to 3.3, 4.2 and 6.0 g C m^?2 yr^?1 at ～100 m depth, and to 1.3, 2.2 and 3.3 g C m^?2 yr^?1 at ～210 m depth. The fraction of settling POC attributable to autochthonous processes occurring at or next to ice break-up was estimated to be 75–84% of the 100 m annual fluxes and to be 61–75% of the 210 m fluxes. Over the three ice-reduced seasons, distinct scenarios between ice conditions, surface POC pools and vertical POC export at 100 m were identified: (1) in 2004, despite a normal ice break-up, a weak primary production was measured and low vertical fluxes were collected as old ice moved across the region; (2) in 2005, a lengthened ice-free period allowed an extended season of surface POC production near-shore, while an intermediate increase of vertical fluxes was recorded offshore; and (3) in 2006, a late ice melt gave rise to a pulsed ice edge bloom and to large vertical fluxes also associated with extra ice-flushed material. Linear regressions of vertical POC fluxes against satellite-derived surface POC concentrations suggested that the pelagic POC retention in the upper 100 m of the Amundsen Gulf ranged from ca. 70% to 90% depending on the timing of ice cover melt. Regardless of the inter-annual variability, the estimated fraction of the surface POC reservoir reaching the 210 m water depth was reduced to ～5%. Therefore, as the Arctic Ocean warms up, our results support the expectation that the increasing extent of the seasonal ice zone will promote the POC pathways that benefit pelagic webs rather than benthic communities.  相似文献   

Occurrence of hydroxylated polychlorinated biphenyls in the brain of cetaceans stranded along the Japanese coast   总被引：1，自引：0，他引：1  

Kunisue T  Sakiyama T  Yamada TK  Takahashi S  Tanabe S 《Marine pollution bulletin》2007,54(7):963-973

Levels of hydroxylated polychlorinated biphenyls (OH-PCBs) and PCBs were measured in the brain of melon-headed whales (MW: Peponocephala electra), striped dolphins (SD: Stenella coeruleoalba) and finless porpoises (FP: Neophocaena phocaenoides) stranded along the Japanese coast during 2002-2003. Levels of OH-PCBs (including identified and unknown OH-P(5)CB, -H(6)CB, -H(7)CB and O(8)CB congeners) in the brain of MW, SD and FP were in the range of 20-290, 21-330 and 170-240pg/g wet wt., respectively. Observed OH-PCB levels were 2-3 orders of magnitude lower than PCBs in the same individuals. OH-PCBs/PCBs ratios in MW, SD and FP brain were lower than those in blood of humans and wildlife and in the brain of polar bears reported previously. OH-PCBs were also detected in maternal and fetal brain of SD (1 pair), suggesting transfer of OH-PCBs into the fetal brain of odontocete cetaceans. When fetus/dam concentration ratios of OH-PCB congeners detected in maternal and fetal brain were estimated, the values were higher than those of PCB congeners, implying that OH-PCBs in maternal blood could be more easily transferred into fetal brain via placenta than PCBs.  相似文献   

Improved satellite ground resolution for sea-ice observation using an inversion method and a priori information     

Sasaki  Y. Teramoto  K. 《Oceanic Engineering, IEEE Journal of》2006,31(1):219-229

The proposals made for improving ground resolution in satellite microwave radiometry primarily seek to sharpen the main beam and refine hardware. However, deformation and changes in electromagnetic characteristics with scanning still significantly affect the antenna patterns of large-aperture antennas. This paper proposes an advanced method with two improvements. The first improvement is related to the method used to obtain a point spreading function (PSF) filter at every spot of interest in the scanning footprint. The method estimates only a typical PSF of the footprint just below the satellite orbit and applies rotation by the angular change that occurs as the footprint moves and rotates with scanning. The second improvement is to introduce a projection onto convex sets (POCS) method into the iterative calculation to solve the inverse problem and to find the most likely estimate of ground information. Two pieces of a priori information are also introduced in the iteration to achieve rapid convergence and reasonable estimation: The brightness temperature of the ground surface is 1) smooth and 2) nonnegative. Correlations between estimated results are also taken between neighboring footprints after retrieval, and convergence is easily attained in the iteration. As no practical satellite data were available, an observational simulation was used as a case study at the lowest frequency (6.9 GHz), which has the poorest resolution. In this case study, ice margins were clearly retrieved by the algorithm when ice floes were 50 km or more apart. Irregularities like ringing, unreasonable undulation, or unreasonable values have occasionally appeared with the current method, but are absent with the proposed improved inversion method used in combination with a POCS method.  相似文献   

The Zurich Extragalactic Bayesian Redshift Analyzer and its first application: COSMOS     

R. Feldmann  C. M. Carollo  C. Porciani  S. J. Lilly  P. Capak  Y. Taniguchi  O. Le Fèvre  A. Renzini  N. Scoville  M. Ajiki  H. Aussel  T. Contini  H. McCracken  B. Mobasher  T. Murayama  D. Sanders  S. Sasaki  C. Scarlata  M. Scodeggio  Y. Shioya  J. Silverman  M. Takahashi  D. Thompson  G. Zamorani 《Monthly notices of the Royal Astronomical Society》2006,372(2):565-577

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