Surrounding Sea Areas Research Articles

Precipitation Characteristic Analysis of the Zhoushan Archipelago: From the View of MSWEP and Rainfall Merging

Based on the long series of gauge rainfall data from 1979 to 2015, the performance of Multi-Source Weighted-Ensemble Precipitation (MSWEP) precipitation dataset in the Zhoushan Archipelago and its surrounding sea area in Southeast China was evaluated from a variety of perspectives, and then the Cressman scheme was used to merge MSWEP with surface gauge measurements. It was found that at the spatial scale of 0.1° × 0.1°, MSWEP correctly detected most of the daily rainfall events in the study area. The surface precipitation was generally underestimated, with a relative deviation no more than 10%, but there was a fairly high miss reporting on heavy precipitation. The performance of MSWEP is also obviously characterized with seasonal fluctuation. Compared with the gauge records interpolation results, the accuracy statistics of rainfall dataset generated by merging MSWEP with gauge observations is improved to a certain degree. Especially its comprehensive identification ability of the dry and wet state for daily precipitation has been obviously raised. In addition, the merged data has the mixed characteristics of rain gauge observations and MSWEP in spatial structure. This paper has deepened the understanding of the performance of MSWEP in islands and sea areas, and also strengthened the understanding of the marginal effect of merging gauge data with MSWEP, even other global precipitation datasets.

РУДНЫЕ, НЕФТЕГАЗОВЫЕ РАЙОНЫ ЮЖНО-ОХОТСКОЙ ПРОВИНЦИИ И ГЛУБИННАЯ ГЕОДИНАМИКА

In the South Okhotsk Sea province – on the islands of Sakhalin, Kunashir, Iturup, Urup and surrounding sea areas – many occurrences of rare, noble metal and other mineralizations as well as of oil-and-gas fields, gas hydrate accumulations, and isolated areas of active emission of water-hydrocarbon gases are known. Occurrences and deposits of solid, liquid and gaseous mineral resources are controlled by hidden deep fault transform zones: Nosappu (Tuscarora), Iturup, and Urup. These long-lived extended (more than 1000 km) zones are distinguished at the N-W Pacific megaplate margin near the S-E flank of the Kuril-Kamchatka trogue. Using the seismotomographic methods we have established their extension to the west from the seismic focal zone in the oceanic slab that subducted into the transition zone of the mantle. In the areas of strike-slip extension the faults accounted for the active formation of the drainage channels for the penetration of the sea water in the lithosphere with the following serpentinization of its ultramafites, and for decompressional generation of ascending mantle-derived abiogenic fluid flows. The latter penetrated from the underslab asthenosphere in the oversubduction mantle wedge and beneath the lithospheric mantle, where they accounted for the development of the processes of metasomatism. The subsequent migration of flows initiated the creation of primary magma reservoirs in the lower parts of the continental lithosphere, and intermediate and peripheral chambers in the Earth’s crust. The injection of melts from the chambers in the consolidated Earth's crust led to the formation of abyssal, hypabyssal intrusive massifs, arch-dome uplifts and magmatogenic-ore (ore-magmatic) systems predominantly among the rocks of the pre-Pliocene basement. The concentration of oil and gas accumulations mainly from the mantle-derived abiogenic hydrocarbons containing mercury, gold, rhenium, and PGE in the Cenozoic sedimentary basins amidst the reservoirs under the impermeable beds also resulted from deep under- and overslab fluid flows.

New method of determining height of atmospheric boundary layer and numerical experiment

In this paper, we propose a new method of numerical differentiation to determine the height of the top layer of the atmospheric boundary layer. In this method, a regularization technique is used to convert the problem of calculating the differential of the curve of the corners into the problem of finding the minimum value of the objective function. The two-parameter model function method is used to select the regularization parameters. Finally, the maximum gradient method is used to determine the top height of the boundary layer. Firstly, the effectiveness of the new method is validated through two numerical experiments. The experimental results show that as the noise of the occultation data increases, the fluctuation of the height of the boundary layer top obtained by the difference method and the numerical differentiation method combined with the L curve scheme increases. And the height obtained by the two-parameter model function method is very stable, which shows that the new method can filter the noise well, thereby retaining the main information about the profile. Then, based on the COSMIC angle data in January, April, July and October 2007－2011, the new method is used to analyze the seasonal characteristics of the height of the global oceanic and atmospheric boundary layer, compared with the seasonal distribution obtained by “zbalmax” with the occultation data. The results show that the seasonal distribution characteristics of the two data are very consistent: the height of the boundary layer is higher in the area where the sea surface temperature is higher than that in the surrounding sea area; on the contrary, the height of the boundary layer top is lower. In the sea area where the warm current passes, the height of the boundary layer is higher; in the sea area where the cold current passes, the height of the boundary layer is lower.

선박재활용협약 국제동향 분석을 통한 국내 대응 방안 연구

The background of adoption of the Ship Recycling Convention is to improve the working environment of workers and to protect the environment of the surrounding sea area. Most developed countries in Europe are in favor of the agreement of Ship Recycling Convention, but Asian countries with ship recycling facilities are lukewarm in Ship Recycling Convention Ratification. The purpose of this paper is to investigate international trends and to analyze the impact on the maritime industry in Domestic. In the field of international relations, the policy trends of the International Maritime Organization, the EUSRR in Europe, and the countries that ratified the this Convention were identified. Based on these results, we would like to analyze domestic situation and prepare a countermeasure.

Phytoplankton community structure and diversity in the indoor industrial aquaculture system for Litopenaeus vannamei revealed by high‐throughput sequencing and morphological identification

The explosive multiplication of phytoplankton caused by water eutrophication often occur in the intensive shrimp aquaculture. To comprehensively assess the diversity and community structure of phytoplankton in the waters of typical indoor industrial aquaculture system for Litopenaeus vannamei, a combination of high-throughput sequencing and morphological identification methods were used in the present study. A total of 41 genera belong to nine phyla were detected by both methods. Chlorophyta, Cyanophyta and Bacillariophyta were found to be three dominant phyla. The high-throughput sequencing revealed that green algae and cyanobacteria were the most dominant phytoplankton; however, diatoms were the first dominant phytoplankton by using the morphological identification. At the genus level, Picochlorum and Synechococcus were dominant, accounting for 20.94%–97.19% and 0.01%–52.81% of total phytoplankton, revealed by the high-throughput sequencing. Therefore, more attention should be paid to their ecological impacts on the surrounding sea areas or potential toxicity to shrimp. Cyclotella was the most dominant genus revealed by the morphological identification. High-throughput sequencing revealed a high diversity and small-sized phytoplankton which were undetected by microscopy. Both methods provide similar information on the environmental drivers of phytoplankton community. NO3−, NH4+, DIP, DSi, DON and DOP concentrations were the main factors influencing the phytoplankton community structure and diversity.

The Impact of Tropospheric Anomalies on Sea-Based JPALS Integrity.

The Joint Precision Approach Landing System (JPALS) addresses tropospheric errors through double-difference and tropospheric model correction. Large residuals occur with two types of tropospheric anomalies: the vertical duct and horizontal non-nominal troposphere. Through analyzing 8 years of meteorological data from the European Center for Medium-Range Weather Forecasts (ECMWF), we find that the two types of anomalies can occur simultaneously. In addition, the existing vertical protection level (VPL) calculation method under tropospheric anomalies is based on the least squares method, which is not applicable to Sea-Based JPALS using the Kalman filter. Therefore, we start by calculating the zenith duct error by numerical integration. The maximum error observed is 45.64 mm, and the error seasonal characteristic is analyzed. For the non-nominal troposphere, the worst meteorological conditions in the Chinese surrounding sea areas are used to calculate the non-nominal errors, which are fitted to a satellite-elevation-dependent model. Then, a VPL calculation method based on the Kalman filter under tropospheric anomalies is proposed. Finally, a multiple approach simulation is conducted. The results show that the average VPL increments introduced by the duct and non-nominal troposphere anomalies are 0.082 m and 0.211 m, respectively, with growth percentages of 12.903% and 30.857%, respectively. The increment under simultaneous anomalies is 0.272 m with a growth of 40.427%. Furthermore, the average availability under normal conditions is 100%. Considering the duct and the non-nominal troposphere anomalies, the availability loss is 0.017% and 3.674%, respectively. Under simultaneous anomalies, this loss is 4.743%.

Assessment of the conservation value of Munseom area in Jeju Island, South Korea

ABSTRACTThe ecosystem of munseom area (MA) in Jeju Island, one of the marine protected areas in South Korea, has been continuously threatened by lack of management and pollution of the surrounding sea area. As a result, the South Korean government is trying to implement the systematic management plan to conserve the marine ecosystem of the MA. This article tries to obtain information about the conservation value of the MA. To this end, this study examines household willingness to pay (WTP) for conserving the MA employing the contingent valuation (CV) approach. A total of 1000 South Korean households were involved in the CV survey using a dichotomous choice question. The mean yearly WTP for the conservation is estimated as KRW 1763 (USD 1.50) per household. The national value expanded from the sample to the population is worth KRW 34.0billion (USD 29.0 million) per year. The results imply that the conservation is supported by South Korean households.

Environmental impact assessment of oilfield upgrades in Bohai Sea

This paper designed 65 environmental monitoring sites to collect samples and analyze for better evaluating the environmental impact generated by cuttings, mud, produced water with oil and oil pollutions that produced during the upgrading in the Bohai Sea where the oil field 34-1 upgraded. Collecting samples include ocean water, marine life and sediments and test items involve PH, dissolved oxygen (DO), salinity, chemical oxygen demand (COD), phosphate, organic carbon, sulfide, inorganic nitrogen, petroleum, copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), total chromium (Cr), total mercury (Hg) and arsenic (As). Meanwhile sample sites collect and analyze the abundance and diversity of marine plants and elaborated the environmental impact caused by upgrading renovation project from the aspects of sea water, marine life and marine sediments. Through analysis and comparison we found that seawater quality conform the Ш seawater quality standards, the excessive rate of Cu is 10%, the average diversity index of marine life is 2.34 and evenness is 0.68. Influence range of marine sediments and pollutants of production is within 2.68km and basically has no serious impact in the surrounding sea area. It’s worth nothing that reconstruction project has the risk of oil spilling and protective measures must be prepared.

Influence of the construction of the Yantai West Port on the dynamic sedimentary environment

ABSTRACTThe development of the Yantai West Port was implemented on a large scale that had an impact on the dynamic environment of the surrounding sea area. Investigations of the tides, tidal currents, water depth, coastlines, and bottom sediment have provided basic data for the West Port surroundings. Based on these data, this paper used the MIKE 21 numerical model to simulate the hydrodynamic processes and the erosion and deposition characteristics of the West Port. The influence of the project on the dynamic sedimentary environment was analyzed by comparisons before and after the construction. The simulation showed that port construction led to a significant change in the tidal currents; however, the area in which the flow velocity changed by more than 10% was more than 10 km away from the port. The erosion in the northeastern part of the harbor area obviously increased, and deposition on the east and west sides was slightly enhanced.

The impact of dike construction on the flow and sediment siltation in the project of Meishan Container terminal phase II

In order to avoid the adverse impact of Qinglongshan deep groove on the flow pattern of the Meishan Container terminal phase II ensuring the safety of berthing, a submarine dike is proposed along the land front direction toward the Qinglongshan Island. The influence of different dike layout schemes on the water flow in the surrounding sea area was studied through the mathematical model. In addition, the effects of different dike heights and gap width on the surrounding water flow and siltation were analysed. The results show that the crossflow in front of the terminal under the two submerged dike heights and gap widths are basically the same, which is less than that of without the construction of the dike. Appropriate reduction of dike height is conducive to improve the flow at the channel between the Qinglongshan and Meishan Island. After the dike construction, the groove will maintain a certain depth, and will not result a blocking at the top side of dike and the rear channel.

Simulation of the effect of an oil refining project on the water environment using the MIKE 21 model

A case study of the Caofeidian oil refining project is conducted. A two-dimensional convective dispersion mathematical model is established to simulate the increase in the concentration of pollutants resulting from the wastewater discharge from the Caofeidian oil refining project and to analyze the characteristics of the dispersion of pollutants after wastewater is discharged and the effect of the wastewater discharge on the surrounding sea areas. The results demonstrate the following: (1) The Caofeidian sea area has strong tidal currents, which are significantly affected by the terrain. There are significant differences in the tidal current velocity and the direction between the deep-water areas and the shoals. The direction of the tidal currents in the deep-water areas is essentially parallel to the contour lines of the sea areas. Onshore currents and rip currents submerging the shoals are the dominant currents in the shoals. (2) The pollutant concentration field in the offshore areas changes periodically with the movement of the tidal current. The dilution and dispersion of pollutants are affected by the ocean currents in different tidal periods. The turbulent dispersion of pollutants is the most intense when a neap tide ebbs, followed by when a neap tide rises, when a spring tide ebbs and when a spring tide rises. (3) There are relatively good hydrodynamic conditions near the project's wastewater discharge outlet. Wastewater is well diluted after being discharged. Areas with high concentrations of pollutants are concentrated near the wastewater discharge outlet and the offshore areas. These pollutants migrate southwestward with the flood tidal current and northeastward with the ebb tidal current and have no significant impact on the protection targets in the open sea areas and nearby sea areas.

Fault Activity in the Surrounding Sea Areas of the Nuclear Power Plant in Cang-Nan, China

The fault activity in the area surrounding a nuclear power plant is crucial and critical for site selection. This study aims to analyze the fault activity in the surrounding sea areas of the Cang-nan nuclear power plant. The strata information is obtained by both a high-resolution multi-channel seismic survey and a single-channel seismic survey. Based on the processed seismic data, the seismic profiles are interpreted by combining the regional tectonic background and the exploration data from the neighboring nuclear power plant. Seven seismic reflection interfaces are obtained by using the seismic stratigraphy method. According to the active fault criterion, no fault is found in the Quaternary sedimentary layer, indicating that no breakpoint exists. The results show that there is no Quaternary active fault in the concerning area of the Cang-nan nuclear power plant (<25 km) and the site can meet the requirements of the industry standard.

An energy balance perspective on regional CO2-induced temperature changes in CMIP5 models

An energy balance decomposition of temperature changes is conducted for idealized transient CO2-only simulations in the fifth phase of the Coupled Model Intercomparison Project. The multimodel global mean warming is dominated by enhanced clear-sky greenhouse effect due to increased CO2 and water vapour, but other components of the energy balance substantially modify the geographical and seasonal patterns of the change. Changes in the net surface energy flux are important over the oceans, being especially crucial for the muted warming over the northern North Atlantic and for the seasonal cycle of warming over the Arctic Ocean. Changes in atmospheric energy flux convergence tend to smooth the gradients of temperature change and reduce its land-sea contrast, but they also amplify the seasonal cycle of warming in northern North America and Eurasia. The three most important terms for intermodel differences in warming are the changes in the clear-sky greenhouse effect, clouds, and the net surface energy flux, making the largest contribution to the standard deviation of annual mean temperature change in 34, 29 and 20 % of the world, respectively. Changes in atmospheric energy flux convergence mostly damp intermodel variations of temperature change especially over the oceans. However, the opposite is true for example in Greenland and Antarctica, where the warming appears to be substantially controlled by heat transport from the surrounding sea areas.

Research on bilateral reverse migration of one-group seabed sand waves in a small shallow shelf sea

Bilateral reverse migration of one-group seabed sand waves is found recently in many small sea areas and is a potential threat to the safety of many near seabed engineering structures, such as pipelines and cables. The mechanism cannot clearly be explained by existing theories. This paper focuses on the bilateral reverse migration of one-group seabed sand waves around a sand ridge in a small shallow shelf sea of the South China Seas, and presents a developed numerical model consisting of three-dimensional wave–current coupling module and sand transport module to simulate this complex phenomenon and perform relative analysis on the characteristics of the current and bilateral reverse migration formation mechanism. Taking the ocean environment characteristics of the surrounding sea area into account and with sufficient grid resolution, this model successfully depicts the process of sand wave bilateral reverse migration. Bottom friction velocity is taken as the inspecting physical quantity and divided into tidal, residual and short-term fluctuation components through harmonic analysis; with a method based on bedload transport calculation, the contributions of the above three parts are determined. It is found that long-term sand wave migration trend is primarily controlled by both tidal constituents and residual velocity. Under nonlinear pure tidal impact, the sand waves migrate southwards; the residual current is northwards and will cancel the tidal impact. When the magnitude of the residual velocity is large enough, i.e., in the western part of the sand wave area, sand waves migrate northwards; when the residual velocity is small, i.e., in the eastern part, sand waves migrate southwards and the bilateral reverse migration pattern is formed. The residual velocity distribution relates closely to the surrounding topography. This paper discloses one kind of mechanisms for bilateral reverse migration of one-group seabed sand waves, and the model and analysis framework can also be extended and applied to other similar situations to prompt deeper and more comprehensive understanding about sand wave migration.

Wave Simulation for Submarine Cable Route of Southwest Sea Offshore Wind Farm Using the SWAN Model

Submarine cable installation is essentials for grid connection between existing power grid and newly produced electricity which will be from offshore wind farm in Southwest sea area of Korea. Especially, submarine cable route and protection method is designed in order to ensure the economical efficiency, workability and stability of submarine cable installation. On this paper, we will give the basic information about the submarine cable route and protection method of offshore wind farm which will be built in Southwest sea area of Korea. For this, we have a numerical simulation at high and low tide based on the third-generation wave model SWAN(Simulating WAves Nearshore) using the long term wave data from Korea Institute of Ocean Science and Technology(KIOST). The results of the study, year mean Hs is 1.03m, Tz is 4.47s and dominant wave direction is NW and SSW When the incident wave direction is NW(Hs: 7.0 m, Tp: 11.76s), the distribution of shallow water design wave height Hs was calculated about 4.0~5.0m at high tide and 2.0~3.0m at low tide. When the incident wave direction is SSW(Hs: 5.84 m, Tp: 11.15s), the distribution of shallow water design wave height Hs was calculated about 3.5~4.5m at high tide and 1.5~2.5m at low tide. The wave direction on a dominant influence in the section of longitude UTM 249749~251349(about 1.6 km) and UTM 251549~267749(about 16.2 km) in the submarine cable route are each NW and SSW. Prominently, wave focusing phenomenon appears between Wi-do and Hawangdeung-do, in this sea area is showing a relatively high wave hight than the surrounding sea areas.

Evolution of sedimentary dynamic environment in the western Jiaozhou Bay, Qingdao, China in the last 30 years

Intensive reclamation and cross-sea bridge construction occurred in the Jiaozhou Bay, Qingdao, China in the last 30 years. These changes have not only reduced water volume but also altered sedimentation in the bay. Using the data collected in the 1980s, 2000s and early 2010s, bottom sediment evolution in the last 30 years in the western bay were studied. Furthermore, a numerical model was used to study the hydrodynamic environment change in the surrounding sea areas. The seabed sediment became finer in the northwestern area from the 1980s to 2003, which was mostly influenced by the reduced sediment discharge from the Dagu River. However, from 2003 to July 2014 during which the Jiaozhou Bay Bridge was built, the seabed sediment became coarser on the north side of the bridge, and became finer on the south side; in particular, two coarser sediment belts appeared across the channel bridge. Numerical simulation results indicated increased current velocity on the north side and decreased velocity on the south side of the bridge. The tidal-duration asymmetry was calculated from the tidal harmonic parameters of the model output. In the flood dominated JZB, the larger deceased tidal-duration asymmetry on the north side of the bridge could result in more coarser seabed sediment brought in from the northern bay. These could be the reasons for the coarser seabed sediment on the north side of the bridge and finer sediment on the south side after the bridge construction. Deeper water on the north side and shallower water on the south side of the bridge from 2005 to July 2014 further demonstrated the effect of hydrodynamic change caused by the bridge construction.

Contemporary sea level in the Chagos Archipelago, central Indian Ocean

Long term mean sea level in the Chagos Archipelago has been relatively stable over the ~20year length of the available instrumental records. Tide-gauge data from Diego Garcia (1988–2000, and 2003–2011) show no statistically significant long-term rise, whilst the rates of rise obtained from the satellite altimeter record for 1993–2011 span the range of 0.16–4.56mmyr−1 in the surrounding sea areas (70–74°E and 4–9°S) and are also consistent with a zero rate except in the far south of the region. The dominant feature is one of considerable inter-annual variability in mean sea level of up to ~10cm, such that the very weak seasonal pattern of highest and lowest sea level in February and May respectively, is absent or reversed in some years. The Indian Ocean Dipole appears to exert an important influence on mean sea level in the area, with positive and negative dipole mode indices preceding periods of elevated or lowered sea levels respectively. The Chagos also lie outside the Indian Ocean cyclone belt and experience relatively low wind speeds, and there is no evidence of changes in the wind or wave environment in the past 20years. Although in an area of seismic activity, there is no record of island subsidence, indeed on Diego Garcia minor crustal uplift of 0.63±0.28SEmmyr−1 has occurred between 1996 and 2009. Collectively, these results suggest that this has been a relatively stable physical environment, and that these low-lying coral islands should continue to be able to support human habitation, as they have done for much of the last 200years. Nonetheless, future sea-level rise and its effect on the Chagos remains an important issue for further studies such as those of the Intergovernmental Panel on Climate Change.

10.1007/s11720-008-1002-z

Large-scale geological maps available for individual areas in the Central Sakhalin Fault zone and geological-geophysical maps of Sakhalin and surrounding sea areas were analyzed to elucidate the tectonic evolution of the fault zone determined by movements of crustal blocks due to the opening of rift basins. Changes in the direction of horizontal compression in the Sakhalin fold system from diagonal (NW-SE) to near-latitudinal resulted in the transformation of near-meridional right-lateral strike-slip faults into reversed faults in the Late Miocene. This allows Sakhalin faults to be interpreted as a zone of recent right-lateral shear between Eurasian and Sea of Okhotsk plates.

人工海浜における養浜砂の安定性評価

An artificial beach, the purpose of which is the prevention of wave didasters and the encouragement of seashore utilization, is being planned in the Takasa-Mobara area in Fukui Prefecture. When planning an artificial beach, an important issue to consider is the management of the nourishment sand which is strewn over the beach after it is built. The nourishment sand must be reviewed in terms of its grain-diameter during the designing stages of the beach so that it does not flow out into the sea under the conditions posed by the facility structure or the waves. This research sought the grain-diameter of the nourishment sand which is stable on the actual area of the sea by taking into consideration the results of a hydraulic model experiment using a plane water tank, and the value obtained from Horikawa's and Sunamura's beach section classification formula. Also, it reviewed the calmness in the artificial beach, wave height in the surrounding sea area, and the influence of the current velocity before and after the facility was serviced.

A 3D magnetic structure of Izu-Oshima Volcano and their changes after the eruption in 1986 as estimated from repeated airborne magnetic surveys

A 3D magnetic inversion method using a conjugate gradient method (CG method) was developed for constructing 3D magnetization models of a volcanic edifice and applied to aeromagnetic anomalies of Izu-Oshima Volcano surveyed in 1986 and in 1997. The calculated results of the 1986 data show that the volcanic edifice of Izu-Oshima Volcano has a mean magnetization intensity ranging from 10.4 to 12.1 A/m. The derived 3D magnetic structure shows low magnetization zones beneath the west-northwest of the western caldera rim, beneath the west-southwest of Mt. Mihara and beneath Mt. Shiroishi. These features may be related with demagnetizations, reflecting a high thermal state due to magma activities in the 1986 eruption. The comparison between 3D magnetization models in 1986 and in 1997, indicates meaningful changes beneath the C-craters erupted in 1986, suggesting a recovery process of demagnetizations and a considerable decrease of magnetization intensities in the foot of Mt. Futago, indicative of demagnetizations. A derived magnetization model including Izu-Oshima Volcano and its surrounding sea areas clarifies the submerged volcanic edifices around Izu-Oshima Island, and suggests that the old volcanic edifices of Fudeshima, Gyojyanoiwaya, and Okata Volcanoes have been affected by eastward migrations due to massive intrusions of a dike-like structure inferred at the base of Izu-Oshima Volcano.