Seasonal volume transport variation in the Tsushima Warm Current through the Tsushima Straits from 10 years of ADCP observations   总被引：2，自引：1，他引：1  

Ken-Ichi Fukudome  Jong-Hwan Yoon  Alexander Ostrovskii  Tetsutaro Takikawa  In-Seong Han 《Journal of Oceanography》2010,66(4):539-551

The seasonal variation in the structure and volume transport of the Tsushima Warm Current through the Tsushima Straits is studied using the acoustic Doppler current profiler (ADCP) data obtained by the ferryboat Camellia between Hakata, Japan and Pusan, Korea from February 1997 to February 2007. A robust estimation method to eliminate the effects of aliasing and tidal signals more accurately leads to a significant increase in the volume transport in winter time compared to the previously reported one by Takikawa et al. (2005) who analyzed this ADCP dataset for the first 5.5 years. The 10 years average of volume transport through the Tsushima Straits is 2.65 Sv, and those through the channels east (CE) and west (CW) of the Tsushima Islands are 1.20 Sv and 1.45 Sv, respectively, which represent a 13% increase and an 8% decrease from those of Takikawa et al. (2005). The transport through the CE increases rapidly from winter to spring and then decreases gradually as winter approaches. On the other hand, the transport through the CW increases gradually from winter to autumn and then decreases rapidly as winter approaches. The transport through the CE is larger than that of through the CW from February to April. The contribution of the Ekman transport near the sea surface, which is not measured with the ADCP, to the seasonal volume transport variation across our ADCP section is not significant.  相似文献   

Field velocity resistivity probe for estimating stiffness and void ratio     

Hyung-Koo Yoon  Jong-Sub Lee 《Soil Dynamics and Earthquake Engineering》2010

Elastic and electromagnetic waves are commonly used to investigate various soil characteristics. The goal of this study is to estimate the elastic moduli and the void ratio based on both the compressional and shear wave velocities, and the electrical resistivity measured by field velocity resistivity probe (FVRP). The compressional and shear waves are measured by piezoelectric disk elements and bender elements installed at the end of the FVRP frame tip. The electrical resistivity is determined by the electrical resistivity probe installed at the tip of the FVRP frame. The FVRP tests are carried out in a clay–sand mixture prepared in a calibration chamber and in silty sand to silty clay soils in the field. The elastic waves and electrical resistivity are measured at every 1 cm. The field tests are carried out at a depth of 6–20 m, at 10 cm intervals, at the Southern coastal area of the Korean peninsula. The measured data are converted into the constraint and shear moduli based on the elastic waves. Void ratios are evaluated based on the elastic wave velocities and the electrical resistivity, and these void ratios match the volumetric void ratio well. This study suggests that the FVRP may effectively determine the elastic moduli and void ratio.  相似文献   

Assimilation of TOPEX/POSEIDON Altimeter Data with a Reduced Gravity Model of the Japan Sea     

Naoki Hirose  Ichiro Fukumori  Jong-Hwan Yoon 《Journal of Oceanography》1999,55(1):53-64

Sea level data measured by TOPEX/POSEIDON over the Japan Sea from 1993 to 1994 is analyzed by assimilation using an approximate Kalman filter with a 1.5 layer (reduced-gravity) shallow water model. The study aims to extract signals associated with the first baroclinic mode and to determine the extent of its significance. The assimilation dramatically improves the model south of the Polar Front where as much as 20 cm² of the observed sea level variance can be accounted for. In comparison, little variability in the northern cold water region is found consistent with the model dynamics, possibly due to significant differences in stratification.  相似文献   

Seismic stratigraphy of the western South Korea Plateau,East Sea: implications for tectonic history and sequence development during back-arc evolution     

Y. K. Kwon  S. H. Yoon  S. K. Chough 《Geo-Marine Letters》2009,29(3):181-189

The western South Korea Plateau in the East Sea (Sea of Japan) is occupied by rifted continental fragments formed in association with the early phase of back-arc opening. The present study focuses on the seismic stratigraphy of the sedimentary succession and the underlying acoustic basement in this region, based on closely spaced multichannel seismic reflection profiles. The sedimentary succession occurs mainly within a series of subparallel basement troughs (grabens or half grabens) bounded by faulted continental blocks (horsts) or volcanic ridges, and commonly floored by extrusive volcanic rocks showing hyperbolic reflectors. These features are strongly suggestive of continental rifting accompanied by normal faulting, volcanic activity and high rates of basin subsidence. The sedimentary succession can be subdivided into four seismic units. Unit 1 is characterized by short and irregular high-amplitude reflectors and interpreted as a syn-rift deposit consisting of a non-marine volcanics/sediment complex in topographic lows. Units 2 and 3 formed in an open marine environment during the Middle Miocene to Early Pliocene, characterized by an onlap-fill and later draping marine sedimentary succession dominantly composed of hemipelagic sediments and turbidites with frequent intercalation of mass-flow deposits. Along the western margin of the plateau, these units were deformed under a compressional regime in the Early Pliocene, associated with the back-arc closing phase. Unit 4 (deposited since the Early Pliocene) comprises hemipelagic sediments and turbidites with evidence of sporadic slides/slumps.  相似文献   

Numerical simulations using momentum source wave-maker applied to RANS equation model   总被引：2，自引：0，他引：2  

Junwoo Choi  Sung Bum Yoon   《Coastal Engineering》2009,56(10):1043-1060

For Navier-Stokes equation model using the VOF scheme, Lin and Liu (Lin, P. and Liu, P.L.-F. (1999). Internal wave-maker for Navier-Stokes equations models. J. Waterw. Port Coast. Ocean Eng., 125 (4), 207–215.) developed an internal wave-maker method for which a mass source function of the continuity equation was used to generate target wave trains. Using this internal wave-maker method, various numerical experiments have been conducted without any problems due to waves reflected by a wave-maker. In this study, an internal wave-maker method using a momentum source function was proposed. Various numerical simulations in two and three dimensions were performed using the momentum source wave-maker applied to the RANS equation model in a CFD code, FLUENT. To verify their applicability in 2 dimensions, the computational results obtained using the momentum source wave-maker in a channel of constant depth were compared with the results obtained by using the mass source wave-maker and with the analytical solutions. And the results of the present numerical simulations of hydraulic experiments, which represent nonlinear waves on a submerged shoal and breaking waves on a plane beach, were compared with measurements. The comparisons showed good agreements between them. To see their applicability into 3-dimensional cases, the present results in a basin of constant depth were compared with the analytical solutions, and they agreed well with each other. In addition, vertical variation of longshore current was presented by using the 3-dimensional simulation results.  相似文献   

Evolution of waves and currents over a submerged laboratory shoal   总被引：1，自引：0，他引：1  

Junwoo Choi  Chae Ho Lim  Jong In Lee  Sung Bum Yoon 《Coastal Engineering》2009

The vertically-integrated effect of interaction between waves and wave-induced currents on wave transformation over a submerged elliptic shoal was investigated based on numerical simulations of the Vincent and Briggs experiment [Vincent, C.L., Briggs, M.J., 1989. Refraction- diffraction of irregular waves over a mound. Journal of Waterway, Port, Coastal and Ocean Engineering, 115(2), pp. 269–284.]. The numerical simulations were performed using two numerical wave-current model systems: one, a combination of the wave model SWAN and the current model SHORECIRC, and the other, a combination of the wave model REF/DIF and the same current model. A time-dependent, phase-resolving wave and current model, FUNWAVE, was also utilized to simulate the experiment. In the simulations, the developed wave-induced currents defocused waves behind the shoal and brought on a wave shadow zone that showed relatively low wave height distributions. For the breaking case of monochromatic waves, the wave heights computed using FUNWAVE showed good agreement with the measurements and the resulting wave-induced currents showed a jet-like velocity distribution in transverse direction. And the computed results of the two model combinations agreed better with the measurements than the computed results obtained by neglecting wave-current interaction. However, it was found that for the case in which transverse interference pattern caused by refracted waves was strong, REF/DIF-SHORECIRC did not correctly evaluate radiation stresses, the gradients of which generate wave-induced currents. SWAN-SHORECIRC, which cannot deal with the interference patterns, predicted a jet-like wave-induced current. For breaking random wave cases, the computed results of the two model combinations and FUNWAVE agreed well with the measurements. The agreements indicate that it is necessary to take into account the effect of wave-induced current on wave refraction when wave breaking occurs over a submerged shoal.  相似文献   

Effect of the along-strait wind on the volume transport through the Tsushima/Korea Strait in September     

Jae-Hong Moon  Naoki Hirose  Jong-Hwan Yoon  Ig-Chan Pang 《Journal of Oceanography》2009,65(1):17-29

Recent investigation suggests that volume transport through the Tsushima/Korea Strait often has double peaks during the summer to autumn period with decreasing transport in September. The satellite-observed wind changes from weak northwestward (across-strait) in summer to strong southwestward (along-strait) in early autumn (September) in the strait. Such a strong along-strait wind is related to tropical cyclones, which frequently pass through the East China Sea in September. The effect of the along-strait wind component on the transport variation is examined using a three-dimensional numerical model. The simulated volume transport through the Tsushima/Korea Strait shows realistic seasonal and intra-seasonal variations. According to sensitivity experiments on local winds, the transport variations in September are mainly generated by strong along-strait (southwestward) wind rather than weak across-strait wind. The strait transport responds to the along-strait wind (southeastward), which produces a sea level increase along the Korean coast, resulting in the geostrophic balance across the strait. The transport minimum through the Tsushima/Korea Strait in September can be determined by the combination of the across-strait geostrophic and along-strait ageostrophic balances. The Editor-in-Chief does not recommend the usage of the term “Japan/East Sea” in place of “Sea of Japan”.  相似文献   

Modeling the effects of atmospheric nitrogen input on biological production in the Japan Sea     

Goh Onitsuka  Itsushi Uno  Tetsuo Yanagi  Jong-Hwan Yoon 《Journal of Oceanography》2009,65(3):433-438

The effects of atmospheric nitrogen input on biological production in the Japan Sea have been investigated using a coupled physical-ecosystem model. Comparison between the cases with and without nitrogen deposition shows a relatively large effect on primary production in the southern Japan Sea during summer to autumn, when nitrogen deposition is high and nutrient is depleted in the surface layer. The atmospheric nitrogen deposition supports > 10% of the annual export production in the nearshore region along the Japanese coast. The importance of atmospheric input as a new nutrient will grow steadily with increasing deposition into the Japan Sea.  相似文献   

Subtidal Marine Algal Community and Endangered Species in Dokdo and Ulleungdo,Two Oceanic Islands in the East Sea of Korea     

Jung  Seung Wook  Oh  Yoon Sik  Rho  Hyun Soo  Choi  Chang Geun 《Ocean Science Journal》2020,55(4):537-547

Ocean Science Journal - Dokdo and Ulleungdo islands harbor diverse marine algae and are therefore uniquely well-suited for research on marine algae distribution and ecological changes. However,...  相似文献   

The first records of two neustonic calanoid copepods, pontella securifer and p. sinica (calanoida, pontellidae) in the south sea, korea     

Hyeon Gyeong Jeong  Hae-Lip Suh  Yang Ho Yoon  Im Ho Choi  Ho Young Soh 《Ocean Science Journal》2008,43(2):91-100

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