Fifty years of the 137°E repeat hydrographic section in the western North Pacific Ocean     

Eitarou Oka  Masao Ishii  Toshiya Nakano  Toshio Suga  Shinya Kouketsu  Masatoshi Miyamoto  Hideyuki Nakano  Bo Qiu  Shusaku Sugimoto  Yusuke Takatani 《Journal of Oceanography》2018,74(2):115-145

The 137°E repeat hydrographic section of the Japan Meteorological Agency across the western North Pacific was initiated in 1967 as part of the Cooperative Study of the Kuroshio and Adjacent Regions and has been continued biannually in winter and summer. The publicly available data from the section have been widely used to reveal seasonal to decadal variations and long-term changes of currents and water masses, biogeochemical and biological properties, and marine pollutants in relation to climate variability such as the El Niño-Southern Oscillation and the Pacific Decadal Oscillation. In commemoration of the 50th anniversary in 2016, this review summarizes the history and scientific achievements of the 137°E section during 1967–2016. Through the publication of more than 100 papers over this 50-year span, with the frequency and significance of the publication increasing in time, the 137°E section has demonstrated its importance for future investigations of physical–biogeochemical–biological interactions on various spatiotemporal scales, and thereby its utility in enhancing process understanding to aid projections of the impact of future climate change on ocean resources and ecosystems over the twenty-first century.  相似文献   

Determination of the freshwater origin of Coastal Oyashio Water using humic-like fluorescence in dissolved organic matter     

Yu Mizuno  Jun Nishioka  Takahiro Tanaka  Yuya Tada  Koji Suzuki  Yuta Tsuzuki  Atsuko Sugimoto  Youhei Yamashita 《Journal of Oceanography》2018,74(5):509-521

Coastal Oyashio Water (COW), defined as a water mass with a temperature lower than 2 °C and a salinity lower than 33.0, is distributed in the North Pacific Ocean off southeastern Hokkaido, Japan, from winter to spring. COW is rich in macronutrients and dissolved iron and is thus considered to affect the spring phytoplankton blooms in the Oyashio region. Although river water and sea-ice melt water have been considered freshwater end-members of COW, the contributions of these freshwater sources to COW have not been well described. In this study, the humic-like components in dissolved organic matter were first applied as a parameter to evaluate the freshwater end-members of COW in March 2015. Linear regressions with negative slopes were determined between the humic-like components and the salinity of COW. The intercepts of the regressions against the humic-like components were within the ranges of those observed for the local rivers of Hokkaido but were very different from those of sea ice. These findings suggest that river water contributed to the COW observed here as a freshwater end-member, although the contribution of sea-ice melt water to COW could not be evaluated. This novel approach also highlighted two different less-saline water masses in COW. The first was characterized by a lower temperature and relatively high levels of humic-like components, while the second was higher in temperature and had higher levels of humic-like components. It is suggested that these different characteristics are due to the contributions of water from different rivers and/or different effects of sea-ice melt water.  相似文献   

Controlling factors of seasonal variation in the nitrogen isotope ratio of nitrate in a eutrophic coastal environment     

Ryo Sugimoto  Akihide Kasai  Toshihiro Miyajima  Kouichi Fujita 《Estuarine, Coastal and Shelf Science》2009,85(2):231-240

  相似文献   

Seasonal Changes in Submarine Groundwater Discharge and Associated Nutrient Transport into a Tideless Semi-enclosed Embayment (Obama Bay,Japan)     

Ryo Sugimoto  Hisami Honda  Shiho Kobayashi  Yoshitake Takao  Daisuke Tahara  Osamu Tominaga  Makoto Taniguchi 《Estuaries and Coasts》2016,39(1):13-26

  相似文献   

A spectroscopic study of Epsilon Aurigae     

Mamoru Saitō  Shusaku Kawabata  Keiich Saijo  Hideo Sato 《Astrophysics and Space Science》1984,99(1-2):269-272

Epsilon Aurigae has been observed during ingress and totality between 1982 and 1983 at Okayama. Analyses of profiles of H line and of radial velocities of neutral hydrogen and metals show that the secondary component consists of at least three parts in structure.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983.  相似文献   

Long-term temperature monitoring in a borehole drilled into the Nojima Fault, southwest Japan   总被引：2，自引：0，他引：2  

Makoto Yamano  Shusaku Goto 《Island Arc》2001,10(3-4):326-335

Abstract Long-term monitoring of temperature distribution in an active fault zone was carried out using the optical fiber temperature-sensing technique. An optical fiber cable was installed in a borehole drilled into the Nojima Fault in Awaji Island, south-west Japan, and the temperature profile to a depth of 1460 m had been measured for 2.5 years (July 1997–January 2000). Although the obtained temperature records showed small temporal variations due to drifts of the measurement system all along the cable, local temperature anomalies were detected at two depths. One at around 80 m seems to correspond to a fracture zone and may be attributed to groundwater flow in the fracture zone. This anomaly had been stable throughout the monitoring period, whereas the other anomaly at around 500 m was a transient one. The water level in the borehole could be estimated from the diurnal temperature variations in the uppermost part of the borehole and may provide information on the hydrological characteristics of the fault zone, which is connected to the borehole through perforations on the casing pipe. Except for these minor variations, the temperature profile had been very stable for 2.5 years. The conductive heat flow calculated from this profile and the thermal conductivity measured on core samples increases with depth, probably resulting from errors in thermal conductivity due to sampling problems and/or from advective heat transfer by regional groundwater flow. Assuming that the middle part of the borehole (less fractured granite layer) is least affected by these factors, heat flow at this site is estimated to be approximately 70 mW/m².  相似文献   

Dynamical instability of the envelope of red supergiants and the lower mass limit for carbon detonation supernovae     

Masayuki Y. Fujimoto  Ken'ichi Nomoto  Daiichiro Sugimoto 《Astrophysics and Space Science》1976,45(1):71-77

We investigated the lower mass limitM _l for the carbon detonation supernovae by testing the dynamical instability of the envelopes of red supergiants. It was found that the dependence ofM _l on the mixing lengthl of convection is appreciable. As a smaller value ofl is assumed,M _l becomes larger. It may be as large as 8M ifl is a third of the pressure scale-height. This is one of the ways to remove the difficulty of overproduction of iron-peak elements involved in the model of the carbon detonation supernovae.  相似文献   

Warm water intrusion from the Kuroshio into the coastal areas south of Japan   总被引：1，自引：0，他引：1  

Akihide Kasai  Shingo Kimura  Takashige Sugimoto 《Journal of Oceanography》1993,49(6):607-624

Sea surface temperature (SST) has been measured in the south of Japan using a thermometer set up in the ferry boat to investigate the characteristics of the warm water intrudes into the coastal areas from the Kuroshio. Time series analysis was applied to the SST data with satellite images and hydrographic observation data from April 1987 to September 1989. The results indicate that the warm Kuroshio water intruded into the coastal areas on the Enshu-nada and the Kumano-nada Seas intermittently with periods of about 50 and 20 days associated with the fluctuation of the Kuroshio path and the Kuroshio frontal disturbance respectively. The intrusion with a 50-day period was dominant when the Kuroshio took a stationary small meander path (B- and C-types). The warm water spread to the west at 20 cm s^–1, and was estimated to have a depth of 150 m at least and supply enough heat to make up the loss due to the evaporation in the coastal area. During the straight path of the Kuroshio, it was detected that the warm water intruded into coastal areas only with a 20-day period. The warm water that intrudes with a period of 20 days spreads to the west at 25 cm s^–1 in a small scale.  相似文献   

Understanding Japanese sardine migrations using acoustic and other aids   总被引：3，自引：0，他引：3  

Tameishi  H.; Shinomiya  H.; Aoki  I.; Sugimoto  T. 《ICES Journal of Marine Science》1996,53(2):167-171

  相似文献   

Direct Current Measurements off Sanriku, East of Japan     

Sachihiko Itoh  Takashige Sugimoto 《Journal of Oceanography》2002,58(6):877-882

One year records of four current meters moored at two sites off Sanriku (39°26′ N, 142°45′ E and 143°E) have been analyzed. Mean currents flowed southward to southwestward with velocity 2.5–7.8 cm s⁻¹. The geostrophic velocity appeared to be surface-intensified, and the flows at 500 m depth have a relationship with the 100 m depth temperature distribution, suggesting the influence of the upper layer flows. At a depth of 1500 m and 2500 m, southward to southwestward flows are thought to be a part of the current flowing southward on the western flank of the Japan Trench. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献