South China Sea Region Research Articles

Interactions between Dongsha Atoll and Mw 9 Tsunamis and their Impacts in South China Sea Region

Tsunamis induced by megathrust in the Manila subduction zone impose alarming threats to the coastal cities in the northern South China Sea (SCS), and risk assessment of tsunami hazards in this region becomes demanding. One distinguishable geographic feature in this region is Dongsha Atoll, which is situated between the tsunami source zone and the China coastline. This study discusses the role of the Dongsha Atoll in modifying the tsunami impacts through numerical simulations of a group of synthetic tsunami events with [Formula: see text]. Three types of representations for the Atoll in the numerical simulations are employed, specifically (i) the real topo-bathymetry of the Atoll is fully resolved (Model-1), (ii) the Atoll is removed (Model-2), and (iii) the Atoll is artificially represented by a cylinder (Model-3). The results show that without the Dongsha Atoll presence (Model-2), the tsunamis can induce a substantial increment of water level behind the Atoll and in the vicinity of the Pearl River Delta (PRD) region in China. While the results obtained by realistically modeling the Atoll (Model-1) show that a large amount of tsunami wave energy/momentum can be entrapped by the lagoon and slowly radiated to the ocean. The interactions between the tsunamis and the Atoll will lead to severe flooding on the Dongsha Island on the west bank of the Atoll. However, the peak water levels behind the Atoll and at the selected mainland coastal sites are reduced, indicating that the Dongsha Atoll can offer some degree of protection for the region in its behind. Meanwhile, a slightly smaller reduction of tsunami heights is reported in the simulations with the Atoll being represented by a cylinder (Model-3), implying that the reduction effects are sensitive to the representations of the Atoll. Therefore, the full model of the topo-bathymetry of the Dongsha Atoll is recommended for future tsunami risk assessments for both Dongsha Atoll and the mainland in the SCS region.

Climatic Effects of the Indian Ocean Tripole on the Western United States in Boreal Summer

Abstract The Indian Ocean tripole (IOT) is an independent mode of ocean–atmosphere circulation centered on the tropical Indian Ocean. This study explores the physical mechanisms of the IOT affecting the western United States climate variation during the boreal summer. We find that the IOT is significantly correlated with both western United States summer surface temperature and precipitation anomalies. During positive IOT events, the westerly wind anomalies over the northern Indian Ocean are intensified by two cross-equator airflows over the tropical eastern Indian Ocean and the east coast of Africa. The resulting convergence of air over the northern Bay of Bengal–Indochina Peninsula–northern South China Sea (NBB–IP–NSCS) region (15°–25°N, 80°–125°E) exacerbates the surplus precipitation there. Serving as a heat source, these NBB–IP–NSCS precipitation anomalies can excite a circumglobal teleconnection (CGT)-like pattern that propagates eastward from west-central Asia toward North America along the Asia subtropical westerly jet, further influencing local circulation anomalies. Development of strong anticyclonic circulation over the western United States enhances descending motion and divergence there, resulting in negative precipitation anomalies. This circulation anomaly also induces the diabatic heating anomalies through allowing more solar radiation to reach the ground surface, further increasing the surface temperature anomalies. Meanwhile, the increased tropospheric temperature also raises local surface temperatures by modulating the adiabatic air expansion and compression. Ultimately, the CGT-like pattern associated with NBB–IP–NSCS precipitation anomalies sets up an atmospheric bridge by which the IOT can impact summer climate in the western United States.

Rancangan Strategi Menangani Ancaman Perang Hybrida Melalui Patroli Maritim di Kawasan Laut China Selatan

The ever-changing dynamics in the South China Sea are making international relations even hotter, especially Western countries that feel threatened by China's claims to the South China Sea region with its Nine Dash Line. The South China Sea claimed by China is the North Natuna Sea which is included in the territory of the Republic of Indonesia. Lately the disputed countries use a new strategy of hybrid war that has been waged by the Chinese state in making a coercion by demonstrating capability in terms of strength. This problem makes Indonesia whose territory is affected in the North Natuna Sea must quickly anticipate in response to hybrid warfare by firmly declaring itself as a non-claimant states participating in the arena of dispute in an effort to claimant-states (state parties) in seizing rights in the South China Sea creating an unconventional war called hybrid warfare. One strategy using the SWOT method can conclude that in a prominent variable with opportunities where variables of cooperation with foreign countries greatly help realize the game, security and stability of the region in the Natuna Sea. The strategy used by increasing the variable strength (Strong) and opportunity (Opportunity) so as to increase the security and stability of the NKRI region in the Natuna Sea .

Discovery of Late Mesozoic volcanic seamounts at the ocean-continent transition zone in the Northeastern margin of South China Sea and its tectonic implication

The Northern South China Sea (SCS) margin experienced the switch from Andean-type active subduction to passive extension during late Mesozoic era. However, the mechanism of cessation of paleo-Pacific subduction in the SCS region is unclear, and the location of suture zone between paleo-Pacific plate and South China block is obscure. In this study, we report new 40Ar/39Ar ages and whole-rock Hf isotopes of basalts from two poorly studied volcanic seamounts (namely, Puyuan and Beipo) at the ocean-continent transition zone in the Northeastern SCS margin, with an emphasis on the existence of exotic, buoyant oceanic plateau and its geodynamic effect on subduction cessation. Results indicate that the OIB-type Puyuan and E-MORB-type Beipo volcanic seamounts were erupted at 154.1 Ma and 93.2 Ma, respectively. Whole-rock trace element, Sr-Nd-Pb-Hf isotopic compositions, and subduction polarity point out that these samples were oceanic intraplate basalts formed within the paleo-Pacific plate, independent of the coeval, Late Mesozoic paleo-Pacific subduction system in the region. The ages and geochemical data of the two volcanic seamounts, combined with geochemical data of Late Mesozoic Pacific oceanic plateaus and seismic data of the Northeastern SCS margin, show that there may exist a Late Mesozoic exotic, buoyant oceanic plateau in the region. The collision between the oceanic plateau and the South China block could lead to the cessation of paleo-Pacific plate subduction, and changes in tectonic regime during the Late Cretaceous era (ca. 100–65 Ma). The pre-existing, Late Mesozoic suture zone has been well constrained by the remnant oceanic plateau and continental arc, and may play a key role in the formation of Cenozoic rifting tectonic units in the region.

Order Euryalida (Echinodermata, Ophiuroidea), new species and new records from the South China Sea and the Northwest Pacific seamounts.

Ophiuroids were collected by the manned submersible ‘Shenhaiyongshi’ from the deep-sea seamounts in the South China Sea and Northwest Pacific regions at 602–1920 m depth, during 2018 to 2020. A total of nine species was identified, including two new species and seven new records from the South China Sea and one new record from the Northwest Pacific region. Two new species are described as Asteroschemashenhaiyongshiisp. nov. and Asteroschemadomogranulatumsp. nov. The seven new records included five species from the genus Asteroschema, and one species each from the genera Asterostegus and Astrodendrum. Comprehensive descriptions of morphological features are provided, including characteristics of the arm skeleton, as well as a phylogenetic analysis based on 16S and COI sequences. Intraspecific genetic distance ranges of Euryalida species from the present study were 0.34% to 1.38%, which was relatively low compared to other orders in the class Ophiuroidea. The present study suggests a high probability that species of the order Euryalida are more widely spread around the Indo-Pacific region than previously expected.

Quantitative Measurement of Radio Frequency Interference for SMOS Mission

The Earth Exploration Satellite Service (EESS) for passive sensing has a primary frequency allocation in the 1400–1427 MHz band. All emissions unauthorized in this band are called RFI (Radio Frequency Interference). The SMOS (Soil Moisture and Ocean Salinity) mission is greatly perturbed by RFI impeding ocean salinity retrieval, especially in coastal areas such as the SCS (South China Sea), where the observed data has been discarded massively. At present, there is no way to eliminate the RFI impact on the retrieved salinity, other than by detecting and shutting down the emissions from the sources. However, it may be effective in a scientific sense if RFI can be quantified and applied to the salinity retrieval process. Therefore, this study proposes an RFI measuring method that can investigate contamination in both prominent and moderate respects, aroused either by on-site emissions or nearby continents. Based on the proposed method, two levels of hierarchical RFI maps of the SCS region, including the separated one and the merged one, are presented and discussed, indicating more severe contamination in northern and western SCS. Moreover, to verify the generalization of the method on open oceans far from continents, an area in the middle central Pacific is selected and tested. The result shows few or no RFI in this unattended region, which is consistent with the authors’ knowledge. This study presents the concept of the “RFI map” to describe the contamination, which will hopefully help researchers comprehend the RFI state intuitively and assist in ocean salinity retrieval statistically.

Prospects for Regional Soft Law to Protect the South China Sea Marine Environment

Abstract International marine environmental law has found its primary sources in international legal principles and conventions. At the regional level, some organisations prefer soft laws as their main instruments for regional marine environmental protection. This article proposes that coastal states could use soft law instruments in the South China Sea (scs) region to protect the marine environment through robust institutional processes, addressing environmental degradation concerns against a tense geopolitical backdrop. Based on discussions of regional practices, this article proposes that scs coastal states could strengthen their regional cooperation efforts using the existing soft-law structures by strengthening implementation cooperation through specific and targeted measures.

Evolution of the Continental Margin of South to Central Vietnam and Its Relationship to Opening of the South China Sea (East Vietnam Sea)

AbstractThe continental margin of south to central Vietnam is notable for its high elevation plateaus many of which are covered by late Cenozoic basalt flows. It forms the westernmost margin of a wide continental rift of the South China Sea (East Vietnam Sea), and uplift has been considered a result of either rifting or younger intraplate basalt magmatism. To investigate margin development apatite thermochronometry was applied to a dense array of samples collected from across and along the margin of south to central Vietnam. Results, including thermal history models, identified a distinct regional episode of fast cooling between c. 37 and 30 Ma after which cooling rates remained low. The fast cooling coincides with a period of fast extension across the South China Sea (East Sea) region that preceded continental break‐up recorded by Oligocene grabens onshore. A thermal model is used test different processes that might influence the inferred cooling including a distinct pulse of exhumation; a decrease in exhumation followed by an associated transient decrease in geothermal gradients and, underplating coincident with rifting. Thermal relaxation following Mesozoic arc magmatism is ruled out as geotherms returned to background rates within 20 Myrs of emplacement, well before the onset of fast cooling. Models support fast cooling attributed to accelerated erosion during early stages of rifting. Some additional heating from either underplating and/or hot mantle upwellings is also possible. No evidence was found to support regional uplift associated with the intraplate magmatism, enhanced monsoon‐driven erosion, or seafloor spreading dynamics.

High genetic differentiation and moderate genetic diversity of the degenerative branching coral Pocillopora verrucosa in the tropical South China Sea

Global warming is causing rapid degradation of coral reefs, among which branching corals are degrading the fastest. An assessment of coral genetic diversity and adaptive potential provides a basis for coral reef protection. In this study, we selected the branching coral Pocillopora verrucosa, a widely distributed species in the tropical South China Sea (SCS), to carry out population genetic studies. To analyze the genetic diversity and structure of 319 P. verrucosa samples from 10 populations in 4 SCS regions, twelve pairs of microsatellite primers and two nuclear markers, ITS and β-tub, were selected. Microsatellite marker results showed moderate genetic diversity for P. verrucosa in the SCS, but relatively low diversity in Dazhou Island and Yongxing Island. The haplotype network showed that P. verrucosa in the SCS was derived from two ancestors, which may be linked to geographical isolation in the Pleistocene glacial period. AMOVA (ΦST = 0.3375) and FST pairwise analysis results based on β-tub showed that the populations were highly differentiated, with most FST values (21/45) > 0.25. Yongxing and Qilianyu Islands populations were significantly different from those in the Xisha area. Mantel test results showed that genetic differentiation among P. verrucosa populations was significantly and positively correlated with both mean sea surface temperature (SST) and SST variance, and was not correlated with distance, chlorophyll-a, or turbidity. The reproductive mode of brooding planulae was an important factor contributing to high genetic differentiation among populations. The moderate genetic diversity of SCS P. verrucosa indicates that this population has a certain genetic potential in the context of global changes, but the high genetic differentiation between populations increases the risk of local degradation or extinction. This study provides a theoretical basis for the protection and restoration of SCS coral reefs.

Implications of Tensions in South China Sea Region on Land Force Strategy in Indonesia's Defense

The South China Sea have strategic value, from economic and military aspects. In some parts of the waters there is an overlap of jurisdictions between claimant states (Brunei Darussalam, Philippines, Malaysia, Singapore, Vietnam, and China), causing a high potential for conflict. Geopolitical turbulence in the South China Sea region further illustrates the dynamic strategic environment and adds complexity to threats to security in the region. The panelitian method used is a qualitative descriptive method. According to Sugiyono, descriptive methods are studies that describe, describe, or describe the state of the object studied as what it is, according to the situation and conditions when research is done. The theories used are balance of power, military of balance, steps-to-war, and balance of threat. China’s rapid military development has made it a powerful country and has the potential to become a hegemony in the region and will create new tensions in the region. This situation encourages countries in the region to increase their military capabilities, produce military weaponry and equipment, and even form military alliances to offset China’s military capabilities in the region. The U.S.-China rivalry makes the South China Sea region a single geostrategic theater that will drag regional countries into the maelstrom of conflict, including Indonesia in it. Facing a dynamic environment, Indonesia with an active defensive strategy deploys land aspect forces that have been centrally structured and dispersed (territorial command units), in an effort to prevent assertive actions from other countries.

Vietnam and Philippines’ Hedging against China in the South China Sea: Economic and Security Perspectives

This article is based on the argument that despite competing for territorial claims and different military stands off, the competing states have shown considerable restraint and hedging behaviors against each other’s to not make the politics of the South China Sea on a point of no return. This assumption is correct in a way that on economic forums like Association of Southeast Asian Nations (ASEAN), they have shown their consensus to resolve their disputes peacefully. But it seems wrong on the pretext that then why this economic interdependence has not provided the space to resolve their perennial territorial disputes in the South China Sea. To find out which assumption seems true, this article is based on the theoretical framework of the Strategic Hedging perspective. This study tries to find the answer to the research question of despite close economic interdependence and military stands offs, why regional states have failed to resolve the SCS dispute? China, the regional hegemon, claims the South China Sea (SCS) region as its core interest and provides the basis for its claims based on historical usage and part of the ancient Chinese dynasties. Vietnam has also shown inflexibility in its claim in the region overlapping with China and other competing states. Honai has also invoked international law to stop the Chinese territorial assertiveness in the region. The Philippines, one of the three important claimants of the SCS, has also tried to take help of the international court of arbitration and the support of global hegemon the US to extend its sovereignty in the disputed islands of the SCS. This article concludes with the findings that Vietnam and the Philippines are using constrain cum hedging to save their national interests from Beijing. Keywords: Politics, Hedging, South China Sea, Economy, Security, Spratly, Paracel

Paleo-Typhoon Events as Indicated by Coral Reef Boulder Deposits on the Southern Coast of Hainan Island, China

The southern coast of Hainan Island, China, is one of the most frequently hit areas of tropical cyclones in the Northwest Pacific regions. Although some of the extreme typhoon events were known in historical times, quantitative information on the timing and magnitude of paleo-typhoon events in this coastal area remains rare. In the present study, a large number of coral reef boulders were found on the Xiaodonghai reef platform, on the south coast of Hainan Island. Morphometric analysis of the boulders shows an exponentially fining landward trend, indicating a storm origin; a wave-induced current velocity of 2.41–5.71 m/s during the storm events is required to transport the boulders that were originally situated outside the reef edge. Based on the U/Th and 14C dating for the age-indicating samples taken from the boulders, seven major periods with intense typhoon activities were identified for the last 4,000 years, i.e., 1800–1500 BCE, 1200–900 BCE, 50–120 CE, 550–800 CE, 900–1000 CE, 1350–1900 CE, and 1910–2000 CE. A comparison with the regional typhoon records in terms of climatic parameters in the northwestern Pacific and the South China Sea regions indicates that the longitudinal variations of intense typhoon frequency were mainly controlled by El Niño-Southern Oscillation (ENSO), dominantly modulated by the Intertropical Convergence Zone. Because of the future warming climate, there will be a trend of enhanced typhoon risk for the southern Hainan Island coasts.

Calming the Waters of the South China Sea: Solving Territorial Disputes over Artificial Islands

The South China Sea region has been a site of conflict for decades, with numerous states holding competing territorial claims due to its abundance of resources and strategic importance. Recently, China’s construction of artificial islands in the South China Sea has escalated tensions in the region and has strained efforts to bring peace. This paper observes the role of intergovernmental organizations such as the United Nations (UN) and the Association of South East Asian Nations (ASEAN) in resolving the conflict in the South China Sea. First, this paper studies the ASEAN-China code of conduct, the dispute management approach currently being negotiated between ASEAN and China. This code of conduct will govern the conduct of the countries involved in the South China Sea disputes. Furthermore, this paper proposes key provisions that should be incorporated into this code of conduct to make it more effective. Second, this paper reviews the conflicting views of ASEAN member states that impede the creation and adoption of the code of conduct. To conclude, this paper recommends an alternative solution through the United Nations Convention on the Law of the Sea (UNCLOS), proposing that the conciliation procedure provided in UNCLOS be adopted to resolve the long standing South China Sea disputes.

The Regionalization of Indonesian Maritime Continent Rainfall based on Integrated Multi-satellite Retrievals for GPM (IMERG)

The need for adequate rainfall data in all regions of Indonesia cannot be achieved only by relying on ground observation tools. This work aims to evaluate the application of spatial satellite rainfall data in characterizing rainfall associated with climatic condition over Indonesia. This study applied an Integrated Multi-satellite Retrievals for GPM (IMERG) data using a double correlation method (DCM). The analysis was carried out in the period April 2014 to March 2019. Before regionalization, IMERG V06 data were validated using observed rainfall data from the Agency for Meteorology, Climatology, and Geophysics of the Republic of Indonesia (BMKG). The results showed that 96% of 154 total validation locations have a high correlation score between IMERG and rain gauges (r = 0.5 – 0.97). IMERG was also able to identify monthly and annual rainfall patterns in Indonesia. Based on DCM, we obtained four rainfall regions in Indonesia. Region A has the monsoonal characteristic, covers central and south Indonesia from south Sumatra to Nusa Tenggara, south parts of Kalimantan, some areas of Sulawesi, and parts of Papua. Region B has an equatorial pattern (semi-monsoonal), located in the equatorial area of Indonesia and covers the west and east part of Sumatra and the north-central part of Kalimantan. Region C, with an anti-monsoonal pattern, covers Maluku, western-central Papua, and parts of Sulawesi. Region D is influenced by monsoon and cold surge characteristics, located in the north part of Sumatera and a small portion of northern Kalimantan to the South China Sea region. Besides the new region D, this research also showed five other differences between IMERG-based map and gridded rain gauges’ data-based map (2003). The regionalization results based on IMERG reveal that there is a possibility of updating areas with certain rainfall characters in Indonesia related to resolution, density, and updates data sources.

Iron isotope constraints on the lithological heterogeneity of the upper mantle in the South China Sea

The South China Sea is located at the junction of the Eurasian, Indian, Australian, and Pacific plates, and thus its evolution is complex and the nature of its sub-ridge mantle remains unclear. Here we present new iron (Fe) isotopic data for mid-ocean ridge and intraplate basalts from the South China Sea region, in order to examine the origins of compositional heterogeneity in the sub-ridge mantle beneath the South China Sea. The investigated mid-ocean ridge basalts are from International Ocean Drilling Program Sites U1431 and U1433 in the eastern and southwestern sub-basins of the South China Sea, respectively. The primary melts of the Site U1431 and U1433 basalts have mean δ56Feprim = +0.06‰ ± 0.04‰ (2SD; n = 10) and +0.02‰ ± 0.02‰ (2SD; n = 3), respectively. The primary melts of the intraplate rocks have highly variable δ56Feprim (+0.04‰ to +0.22‰). Our new and previously published data show that the δ56Feprim values and Fe/Mn ratios of the Site U1431 and U1433 basalts are positively correlated (r2 = 0.42). This result indicates that the heterogeneous Fe isotopic compositions of the studied basalts reflect distinct mantle source lithologies (i.e. pyroxenite and peridotite) that have also been identified from the chemistry of olivine phenocrysts. Co-variations between δ56Feprim values and Mg–Sr–Nd isotopes for the South China Sea basalts suggest that the end-member components in the sub-ridge mantle include an enriched recycling-related pyroxenitic component with high δ56Fe and low δ26Mg, and a ubiquitous depleted subduction-modified peridotitic component with low δ56Fe and high δ26Mg.

Cross-oceanic distribution and origin of microplastics in the subsurface water of the South China Sea and Eastern Indian Ocean

Marine microplastic (MP) pollution is a global environmental problem that has received attention from scientific researchers and the public for the past several decades. However, without a suitably large-volume sampling method, the presence of MPs in subsurface water (< 5 m) is poorly understood. Here, MP content in subsurface water was determined using a pump-underway ship intake system along the cross-oceanic transect from the Pearl River Estuary to the Indian Ocean. The study regions have always been considered as one of the major MPs hotspots in the global oceans and still lack of study. Generally, MP abundance ranged between 0 and 4.97 items m-3, with an overall mean value of 0.40 ± 0.62 items m-3. A total of 679 MP particles were identified using μ-FT-IR. These collections identified polyethylene (PE), polypropylene (PP), and polyester (PET) as the major polymers represented (73.14–88.81%). The presence of MPs in coastal regions was significantly higher than that in the open ocean, revealing the contribution of land-based sources to marine MPs and the ocean dynamics. Therefore, an effective and feasible way to retard the penetration of MPs into the marine environment is to exhibit controls at the source. No significant correlation was found between the MP abundance and the physical and chemical properties of water. The results of the analysis of similarities (ANOSIM) and non-metric multidimensional scaling (NMDS) also showed that MP communities in different environments were significantly greater than the differences in different sites within the same environment. These findings of this study provide reliable information on MP distribution and characterization in cross-oceanic region of South China Sea and Eastern Indian Ocean, which will help to improve our understanding about the fate of MPs in the ocean.

Digital Navigator on the Seas of the Selden Map of China: Sequential Least-Cost Path Analysis Using Dynamic Wind Data

During the age of sail-powered ships, the maritime trade networks of Southeast Asia were highly cyclical in nature due to the biannually switching wind directions of the East Asian Monsoon. The Selden Map of China provides us with a glimpse of these connections in the early seventeenth century, and it is drawn in a unique way that allows the sailing durations between ports to be measured. In this paper, a novel method of simulating directed sail-powered voyages is developed. The method utilizes ArcGIS Pro’s functionality through Python macros, and unlike the previous least-cost path (LCP) sailing models, it is based on sequential LCP analysis using dynamic real-time series wind data. The optimized routes and sailing durations generated by the macros are then compared against the Selden map. In general, the model performs reasonably well in favourable winds, but is unable to simulate tacking properly in adverse conditions. The results allow the visualization of wind patterns in terms of time spent at sea and demonstrate the inherent natural rhythm of maritime movement and trade in the South China Sea region. The macros are freely available and can be modified to simulate directed sailing in other time periods, localities, and environmental settings.

Numerical study on impacts of a concurrent storm-tide-tsunami event in Macau and Hong Kong

Intensified activities of tropical cyclones in the Western North Pacific have imposed increasing threats to coastal cities in the context of global climate change. A storm surge superimposed with astronomical high tide, i.e., a storm-tide event, often causes severe flooding in many coastal cities in South China Sea (SCS) region. Meanwhile, the potential tsunami hazard associated with the megathrust in Manila subduction zone has become a serious concern in this region. These two kinds of coastal hazard have been studied independently in the past since they are caused by different physical mechanisms in nature. However, there is no scientific reason to rule out the possibility of concurrence of a storm-tide-tsunami event, which is admittedly rare. This study simulates a group of synthetic events assuming that tsunami waves are generated by a Mw 9 earthquake in the Manila subduction zone during a typhoon, which has the same characteristics as the 2017 Typhoon Hato. A numerical model package originally developed for storm-tide calculation has been modified to simulate a concurrent storm-tide-tsunami event. A variety of scenarios are considered as the tsunamis are superimposed at different phases of the storm-tide event. Their compound impacts on Macau and Hong Kong in Pearl River Delta, China, are investigated. Specifically, the results of water level, arrival time of the maximum water level, flow velocity, and inundation depth are discussed. The worst-case scenarios have been identified at Macau and Hong Kong, respectively. The scenario with tsunami being initiated at 07:00 on 23-Aug-2017 leads to an inundated area of 12.0 km2 in Macau. On the other hand, the scenario with tsunami being started at 08:10 on the same day generates an inundation area of 8.9 km2 in the vicinity of Kai Tak terminal region in Hong Kong. In addition, the efficacy of the linear superposition of results obtained separately for each hazard (i.e., typhoon and tsunamis) is also discussed. Generally speaking, the differences between the linearly superimposed solutions and fully coupled results vary temporally and spatially and could be either positive or negative. However, the linearly superimposed solutions consistently underestimate the maximum water elevation and yield delays on the arrival times of peak flooding stage in the Pearl River estuary. It is concluded that for coastal protection and hazard mitigation planning in this region, these extreme situations need to be considered. A fully coupled numerical model package is now available for conducting such studies.

SENSITIVITY ANALYSIS OF PRECIPITATION AND RUNOFF PARAMETER TO ASSESS NEMO/INDO12 MODEL OUTPUT Bayu Priyono

We investigate the sensitivity of precipitation and runoff parameters to a set of NEMO/INDO12 scenarios. A series of simulations are imposed based on reduction rate of each precipitation and runoff parameter to examine its influences to the main ocean characteristics behavior (temperature and salinity). One-set evaluates of two different simulations by using normal and reduce precipitation rate on whole domain Indonesian Sea Water, and the other-set evaluates of two simulations which focusing the experiment by reduce precipitation and runoff rate only on South China Sea region. Our results elucidate the complexity of the relationship between the varied of precipitation and runoff reduction rate, showing that the control of precipitation and runoff rate produced significant impacts on salinity profile up to subsurface stratification. Additionally, the reduction rate of precipitation and runoff indicated that the temperature changes do not always response significantly.

Regional Cooperation in Marine Plastic Waste Cleanup in the South China Sea Region

This paper uses countries in the South China Sea Region (SCSR) as examples to study the level of regional cooperation in the marine plastic waste cleanup initiative. We designed a cooperation model to investigate the “cleanup system” from the Ocean Cleanup initiative to reduce marine plastic pollution. The non-cooperative game theory was applied to regional cooperation. The simulation results indicate that the plastic waste cleanup cooperation in the SCSR is related to the plastic trade network structure, the influence parameters of the Experience-Weighted Attraction learning model, and the economic effects. The results suggest that regional cooperation in the cleanup system in the SCSR is feasible, and it could create a significantly larger investment in the cleanup project than the current project attracts. Therefore, countries in the SCSR should adjust their laws and policies to make a good cooperative environment and to maximize the contribution to the marine plastic waste cleanup.