Takehiro Nakamura
Nagasaki University
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Publication
Featured researches published by Takehiro Nakamura.
Journal of Oceanography | 2000
Masako Nogami; Takeshi Matsuno; Takehiro Nakamura; Tadashi Fukumoto
We have observed the temporal variation of oxygen deficient water with short time scale (less than a few days) in the central area of Ohmura Bay, Kyushu, Japan, in summer, 1995 and 1996. The vertical profiles of temperature were similar to those of dissolved oxygen. We noticed a linear relation between temperature and dissolved oxygen in the bottom layer, and applied the T-DO relation to estimate the net oxygen consumption rate, rather than direct evaluation of the advection and diffusion. Oxygen consumption rate just above the bottom was estimated to be about 0.21 g O2 m−3day−1 in July 1995, and about 0.28 g O2 m−3day−1 in August 1996. The net oxygen consumption rate estimated for the bottom layer below the second thermocline was about 0.61 g O2 m−3day−1 with variability from 0.55 to 0.66 g O2 m−3day−1 during July 25 to 29, 1995. This is was about 0.64 g O2 m−3day−1 with variability from 0.18 to 1.4 g O2 m−3day−1 during August 22 to 30, 1996. The net oxygen consumption rates are about half of those measured with a closed system in the Seto Inland Sea.
ieee international radar conference | 2008
Takumi Yoshii; Shin’ich Sakai; Takaki Tsubono; Masafumi Matsuyama; Akihide Tada; Takehiro Nakamura
An ocean radar with a VHF band is a useful tool for surveying coastal currents in a wide area. We have conducted a field observation of currents in Ariake Bay, the large inner sea located in the western part of Japan. Although the number of valid data acquired (hereafter, data acquisition) varies temporally and spatially, the mechanism of such variation is not yet well understood. Our aim in this study is to investigate the impact factor affecting data acquisition through field observations of current, salinity and wind in Ariake Bay. As a result, the data acquisition and the maximum measurement distance of the radar decreased owing to the decreases in salinity and wind speed. After receiving much rainfall, the data acquisition decreased rapidly in accordance with the decrease in surface salinity influenced by run-off from adjacent rivers and a flood control dike. Also, when wind speed became less than 2 m/s, the intensity of the signals received was not sufficient for the detection of current velocity. In conclusion, salinity and wind speed are important factors for steady-current observation using ocean radars.
PROCEEDINGS OF COASTAL ENGINEERING, JSCE | 2007
Akihide Tada; Kenta Takenouchi; Sinsaku Someya; Shin'ichi Sakai; Michihiro Mizunuma; Takehiro Nakamura; Takaki Tsubono
This study deals with the field observations on coastal surface currents by means of both Digital Beam Forming marine radar (DBF ocean radar) and Acoustic Doppler Current Profilers (ADCP) in order to realize characteristics of flow around the mouth of Isahaya Bay. In particular, the former has started since 2005. On the other hand, the latter has carried out seven times since 2001. As a result, it is found out that the feature of the M2 consituent flow detected by the DBF ocean radar was widely coincided well with other ADCP field observation data. Not only the river runoff in the head of Ariake Sound but also a flush flow from the sea-dike gate contribute to the surface currents around the mouth of Isahaya Bay significantly.
Journal of Japan Society of Civil Engineers | 2010
Akihide Tada; Yasuhiro Nakamura; Kazuya Abe; Akira Tai; Seiji Suzuki; Takehiro Nakamura
Doboku Gakkai Ronbunshuu B | 2010
Takumi Yoshii; Takaki Tsubono; Shin'ichi Sakai; Masafumi Matsuyama; Akihide Tada; Takehiro Nakamura
Estuarine and Coastal Modeling | 2000
Tadashi Fukumoto; Takehiro Nakamura
Estuarine and Coastal Modeling | 1998
Tadashi Fukumoto; Akihide Tada; Takehiro Nakamura; Hiroyoshi Togashi
Coastal Environmental and Ecosystem Issues of the East China Sea | 2010
Akihide Tada; Takehiro Nakamura; Shin'ichi Sakai; Michihiro Mizunuma; Kenta Takenouchi
Journal of Japan Society of Civil Engineers | 2009
Akihide Tada; Kazuya Abe; Takehiro Nakamura; Kenta Takenouchi
PROCEEDINGS OF COASTAL ENGINEERING, JSCE | 2008
Kenta Takenouchi; Akihide Tada; Takehiro Nakamura; Eijirou Mori