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11.
Mapping shoreline changes along coastal regions is critically important in monitoring continuously rising sea surface heights due to climate change and frequent severe storms. Thus, it is especially important if the region has very high tidal ranges over very gentle tidal flats, which is a very vulnerable region. Although the various remote sensing platforms can be used to map shoreline changes, the spatial and temporal resolutions are not enough to obtain it for a short time. Accordingly, in this study we introduce the newly developed low altitude Helikite remote sensing platform to achieve much better resolutions of shorelines and a bathymetry. The Helikite stands for Helium balloon and Kite, which is a kind of aerial platform that uses the advantages of both a Helium balloon and a kite. Field experiments were conducted in the Jaebu Island, off the coast of the west Korean Peninsula in January 29, 2011. In order to extract shorelines from the consecutive images taken by the low altitude Helikite remote sensing platform, active contours without edges (ACWE) is used. Edges or boundaries exist primarily on places between one type of objective and the other. Since the hydrodynamic pressure has an effect everywhere, the locations of the waterlines can be the isobath lines. We could map several waterlines, which would enable us to complete a local bathymetry map ranges from 35 to 60 cm depth. The error resulting from applying ACWE algorithm to the imagery to determine the waterline is approximately less than 1 m. Therefore, it is very unique way to obtain such high resolutions of bathymetry with high accuracy for the regions of extremely high tidal ranges for a short time. 相似文献
12.
To understand the effects of the Yellow Sea Cold Bottom Water(YSCBW)on the diel vertical migration(DVM)of the copepod Calanus sinicus,we surveyed vertical distribution of C.sinicus at a fixed station in the Yellow Sea before(spring)and during(summer)formation of the YSCBW.Cold water(<10 C)was observed in the bottom layer when the water column was thermally stratified in summer,but the water column was thermally well-mixed in spring 2010.Samples were collected from five different layers at 3-h intervals using an opening-closing net.Adult females(1–155 ind./m3)showed a clear normal DVM pattern throughout the entire water column in spring,whereas adult males did not migrate.DVM of copepodite V(CV)individuals was not clear,but the maximum abundance of CI–CIV occurred consistently in the upper 10–20 m layer,where there was a high concentration of chlorophyll-a(Chl-a)(0.49–1.19μg/L).In summer,weak DVM was limited to cold waters beneath the thermocline for adult females(<30 ind./m3),but not for adult males.The maximum abundance of CI–CIV also occurred consistently in the subsurface layer(20–40 m)together with high concentrations of Chl-a(0.81–2.36μg/L).CV individuals(1–272 ind./m3)moved slightly upward nocturnally to the near-surface layer(10–20 m),where the average temperature was 25.74 C,but they were not found in the surface layer(0–10 m;28.31 C).These results indicate that the existence of the YSBCW affected food availability at depth and the vertical temperature distribution,leading to variation in the amplitude and shape of stage-specific vertical distributions(CI to adults)in C.sinicus before and during the formation of cold waters in the Yellow Sea during the study period. 相似文献
13.
CHOI Jinyong JUN Kicheon CHOI Youngkwang CHO Kyoungho KWON Jae-Il PARK Jinsoon PARK Kwangsoon 《海洋学报(英文版)》2015,34(12):11-18
The Maenggol Channel and Uldolmok Strait, located on the south-west coast of Korea, have notably strong and complex currents due to tidal effects and to local geological factors. In these areas, electric power has been generated using strong tidal currents, the speed of which is more than 3 m/s during spring tides. The region also provides a shortcut for navigation. These tidal conditions are therefore sometimes useful, but may also cause terrible accidents or severe economic damage, in the absence of accurate information regarding ocean conditions. In April 2014, the passenger ferry MV Sewol capsized in the Maenggol Channel, with 295 passengers killed and 9 still missing. While this was unquestionably a man-made disaster, strong currents were one of the contributing causes. It was also difficult to conduct scuba diving rescue operations given strong current speeds, and accurate prediction of the time when the tide would turn was thus critically needed. In this research, we used the high-resolution coastal circulation forecasting system of KOOS (Korea Operational Oceanographic System) for analysis and simulation of strong tidal currents in such areas with many small islands, using measurements and modeling from this research area. For accurate prediction of tidal currents, small grid size-modeling was needed, and in this study, we identified a suitable grid size that offers efficiency as well as accuracy. 相似文献
14.
辽河盆地大民屯凹陷沈95区块砂岩储层中钙质夹层研究 总被引：3，自引：0，他引：3
钙质夹层是控制剩余油形成与分布的主要因素之一.辽河盆地大民屯凹陷沈95区块钙质夹层十分发育,利用丰富的岩心、测井资料,识别并探讨了钙质夹层的分布规律及成因.研究表明:本区钙质夹层是早期无铁碳酸盐与晚期含铁碳酸盐胶结形成的两期夹层;早期钙质夹层主要分布于泛滥平原亚相、三角洲平原亚相;晚期钙质夹层主要发育于三角洲前缘亚相,且一般位于砂泥岩接触带,厚层砂岩顶底部碳酸盐胶结物较中部高.早期钙质夹层是沉积期、成岩早期,蒸发作用使富钙孔隙水中的钙质沉淀形成的;晚期钙质夹层是在有机酸作用下,Ca2+、Mg2+在烃源岩(泥岩)中溶解,再于储集岩(砂岩)中沉淀形成的.根据夹层的分布规律可以更有效地挖掘剩余油. 相似文献
15.
The effects of sea surface temperature(SST) data assimilation in two regional ocean modeling systems were examined for the Yellow Sea(YS). The SST data from the Operational Sea Surface Temperature and Sea Ice Analysis(OSTIA) were assimilated. The National Marine Environmental Forecasting Center(NMEFC) modeling system uses the ensemble optimal interpolation method for ocean data assimilation and the Kunsan National University(KNU) modeling system uses the ensemble Kalman filter. Without data assimilation, the NMEFC modeling system was better in simulating the subsurface temperature while the KNU modeling system was better in simulating SST. The disparity between both modeling systems might be related to differences in calculating the surface heat flux, horizontal grid spacing, and atmospheric forcing data. The data assimilation reduced the root mean square error(RMSE) of the SST from 1.78°C(1.46°C) to 1.30°C(1.21°C) for the NMEFC(KNU) modeling system when the simulated temperature was compared to Optimum Interpolation Sea Surface Temperature(OISST) SST dataset. A comparison with the buoy SST data indicated a 41%(31%) decrease in the SST error for the NMEFC(KNU) modeling system by the data assimilation. In both data assimilative systems, the RMSE of the temperature was less than 1.5°C in the upper 20 m and approximately 3.1°C in the lower layer in October. In contrast, it was less than 1.0°C throughout the water column in February. This study suggests that assimilations of the observed temperature profiles are necessary in order to correct the lower layer temperature during the stratified season and an ocean modeling system with small grid spacing and optimal data assimilation method is preferable to ensure accurate predictions of the coastal ocean in the YS. 相似文献
16.
Ki-Young Heo Jeong-Wook Lee Kyung-Ja Ha Ki-Cheon Jun Kwang-Soon Park Jae-Il Kwon 《Natural Hazards》2009,51(1):151-162
High-quality informations on sea level pressure and sea surface wind stress are required to accurately predict storm surges
over the Korean Peninsula. The storm surge on 31 March 2007 at Yeonggwang, on the western coast, was an abrupt response to
mesocyclone development. In the present study, we attempted to obtain reliable surface winds and sea level pressures. Using
an optimal physical parameterization for wind conditions, MM5, WRF and COAMPS were used to simulate the atmospheric states
that accompanied the storm surge. The use of MM5, WRF and COAMPS simulations indicated the development of high winds in the
strong pressure gradient due to an anticyclone and a mesocyclone in the southern part of the western coast. The response to
this situation to the storm surge was sensitive. A low-level warm advection was examined as a possible causal mechanism for
the development of a mesocyclone in the generating storm surge. The low-level warm temperature advection was simulated using
the three models, but MM5 and WRF tended to underestimate the warm tongue and overestimate the wind speed. The WRF simulation
was closer to the observed data than the other simulations in terms of wind speed and the intensity of the mesocyclone. It
can be concluded that the magnitude of the storm surge at Yeonggwang was dependent, not only on the development of a mesocyclone
but on ocean effects as well. 相似文献
17.
Magnolia obovata, a tree species native to Japan, is a traditional landscaping tree that has also been introduced to various countries. M. obovata individuals have recently emerged in non-planting areas in Korea, prompting us to investigate its distribution by establishing Dosolsan in an urban forest of Daejeon City as the target site. In order to determine its naturalization, the study explored the status of population growth by examining the diameter at breast height of the individuals, and diameter diminution quotient was calculated. Cores of the trees were collected, and the age distribution was estimated by regression analysis. Reproduction possibility was analyzed by verifying the flowerblooming and fruit-bearing. Spontaneous colonization was investigated in the other potential sites which have different location and environment, respectively.The diameter distribution showed a reverse J-shaped curve, and the diminution quotient was ≥ 1.8. The population was composed of different generations,thus confirming the growth of the population. The distributed M. obovata grew and flowered normally,and followed a normal life cycle. The same phenomenon was observed in other planting areas,residual forests in urban or rural areas, alluvial islands, and mountain forests. The continuous spread of M. obovata in new ecosystems may be attributable to its long-term distribution by birds, relatively fast growth, and maturity time. Investigations on the naturalization and spread of M. obovata in Korea, as well as in various countries, are warranted. 相似文献
18.
During the summer in the Yellow Sea and East China Sea, the resuspension of the bottom sediment is obstructed by strong stratification and, as a result, the concentration of total suspended sediment (TSS) can be used as an excellent tracer for Changjiang Diluted Water (CDW). To analyze the spatial and temporal variations of the CDW distribution, the monthly mean TSS from Moderate Resolution Imaging Spectroradiometer (MODIS) ocean color data are constructed and are converted to salinity using the relationship between salinity observed from AQUARIUS and TSS. The process produces the detailed horizontal distribution of salinity with very high resolution (1 km). From monthly mean salinity map from 2002 to 2012 in July and August, the expansion patterns of CDW are analyzed. The southerly wind in July and southeasterly wind in August transport the CDW eastward and northeastward, respectively. It is found that the yearly variation of the expansion of CDW toward the southern sea area of Korea is mostly due to the variation of southerly wind and the fluctuations of fresh water discharge into the Changjiang estuary show relatively little impact on the eastward extend of CDW. When 11-year mean (from 2002 to 2012) salinity map in August is compared with World Ocean Atlas 2013, it is revealed that wind in August strengthened six times from 1994 and it causes the expansion of CDW extended 150 km further eastward. 相似文献
19.
20.
Sang Heon Lee Jongseong Ryu Dabin Lee Jung-Woo Park Jae-Il Kwon Jingping Zhao 《地理信息系统科学与遥感》2019,56(5):794-810
Phytoplankton size classes (hereafter, PSCs) were derived from satellite ocean color data using a present phytoplankton abundance-based optical algorithm in the northern Bering and southern Chukchi Seas to characterize the spatial and seasonal variations of the different PSC and investigate the contributions of small phytoplankton to the total phytoplankton biomass. The comparison results showed that the phytoplankton abundance-based method approach could reasonably classify the three PSCs (pico-, nano-, and micro phytoplankton). The satellite maps of the dominant PSCs were derived using long-term satellite ocean color data. The general spatial distribution showed that the large (micro-) phytoplankton were dominant in the coastal waters and the west side of the Bering strait, while the small size (nano- or pico-) phytoplankton were dominant in the open ocean waters. Nano- and microphytoplankton were dominant in May and October in most of the study area, while pico-phytoplankton were dominant in the summer months in the open ocean waters. The annual variation in small phytoplankton dominance had a strong positive relationship with the annual mean sea surface temperature (SST), which is consistent with the increasing dominance of small phytoplankton biomass as water temperature increases. Microphytoplankton have an apparent increasing trend in the southeastern Chukchi Sea but slightly decreasing trends in Chirikov and St. Lawrence Island Polynya (SLIP). In contrast, there were increasing trends in picophytoplankton in Chirikov and SLIP, which seems to be related to increasing annual SST. It is crucial to monitor changes in dominant groups of phytoplankton community in the Bering and Chukchi Seas as important biological hotspots responding to the recent changes in environmental conditions. 相似文献