Current Circulation Patterns Research Articles

KAJIAN EFEKTIFITAS POLA SIRKULASI KAWASAN WISATA DESA TRADISONAL PENGLIPURAN

Bali, as one of the main tourist destinations in Indonesia, has a variety of attractions, including the Penglipuran Traditional Tourism Village in Bangli Regency. The popularity of this tourist village has led to a significant increase in vehicle flow, especially on weekends and holidays, resulting in congestion around tourist areas. Vehicles parked carelessly on the side of the road interfere with mobility for both locals and other tourists. This study aims to evaluate the effectiveness of current circulation patterns and identify potential solutions. Using a qualitative method with a naturalistic approach, this study will observe and analyze vehicle movement patterns, parking behavior, and their impact on traffic and visitor comfort. The results of this study are expected to provide recommendations for more effective circulation pattern arrangement, including parking management, alternative routes, and road infrastructure improvements. With the implementation of the right solutions, it is hoped that the comfort and experience of tourists in the Penglipuran Traditional Tourism Village can be significantly improved, while maintaining smooth traffic for local residents.

Human bocavirus in Saudi Arabia: Molecular epidemiology and Co-infections among children with acute respiratory tract infections during 2014–2016

Respiratory tract infections due to a variety of viruses continue to threaten the human population worldwide, particularly in developing countries. Among the responsible viruses, Human Bocavirus (HBoV), a novel discovered virus, causes respiratory tract and gastroenteritis disorders in young children. In Saudi Arabia, data regarding virus molecular epidemiology and evolution and its implication in respiratory tract infection are scarce. In the current study, genetic diversity and circulation pattern of HBoV-1 among hospitalized children due to acute respiratory tract infection (ARTI) during two consecutive years were charted. We found that 3.44% (2014/2015) and 11.25% (2015/2016) of children hospitalized due to ARTI were infected by HBoV-1. We have shown that HBoV was detected year-round without a marked seasonal peak. HBoV-1 also was co-detected with one or multiple other respiratory viruses. The multisequence analysis showed high sequence identity (∼99%) (few point mutation sites) between strains of each genotype and high sequence variation (∼79%) between HBoV-1 and the other 3 genotypes. Phylogenetic analysis showed the clustering of the study's isolates in the HBoV-1 subclade. Our data reveal that genetically conserved HBoV-1 was circulating among admitted children during the course of the study. Further epidemiological and molecular characterization of multiple HBoV-1 strains for different years and from all regions of Saudi Arabia are required to understand and monitor the virus evolution.

Global paleobiogeography of Albian–Cenomanian (mid-Cretaceous) marine ostracods

Despite their potential for providing important information for paleobiogeography, studies using ostracod assemblages compiled from global datasets have been scarce so far. In this study, the paleogeographic implications of the relationship between different ostracod assemblages are analyzed and discussed for the Albian and Cenomanian. We compiled an ostracod dataset at the genus level, with 168 genera for the Albian and 174 for the Cenomanian, to which different multivariate statistical methods of grouping were applied. The affinity between different ostracod assemblages from different regions allowed for the delineation of 30 operational geographic units (OGUs) for the Albian, and 32 OGUs for the Cenomanian, grouped in three paleobiogeographic units (PBUs; Megatethys, Persia, and Austral) and one sub-unit (PBSU; Maghreb associated to the Megatethys). The Maghreb PBSU showed minor changes between the Albian and Cenomanian. The relationship among the OGUs grouped in each PBU is related to different factors, such as eustatic sea level events, similar climatic zones, and marine current circulation patterns. A relationship was observed between the Gabon and Nigeria OGUs with the Persia PBU, which suggests a direct east–west connection between them during the Cenomanian. The affinity observed in the Austral PBU between the South American, South African, and Australian regions during the Albian can be explained by their relative geographic isolation due to the Walvis Ridge barrier. The eventual flooding of this barrier led to the relationship observed between the SE Brazilian and Bolivian regions with the Austral PBU. Finally, the data also suggested that the separation of the Indian subcontinent from the Austral PBU took place during the Cenomanian.

Effect of Water Circulation on the Distribution of Zooplankton in the Southern Waters of Peninsular Malaysia

The waters of Peninsular Malaysia located between the South China Sea and the Straits of Malacca are greatly influenced by two different monsoons: the Southwest Monsoon (SW) and the Northeast Monsoon (NE). Zooplankton are known to be receptive to any environmental changes. Apart from biotic and abiotic changes, the movement of water currents also has an impact on the distribution and composition of zooplankton, as this group is considered a passive swimmer that is dependent on the movement of water currents. This study was conducted to determine the effect of water movement in the southern waters of Peninsular Malaysia on the distribution of zooplankton. Sampling was done in three main areas: Kukup, Pengerang, and Pulau Besar. A total of 16 stations with three replicates per station were performed using a plankton net with a mesh size of 140µm. Results show that zooplankton in Pengerang recorded the highest with 256.157 ind/ m3, followed by Kukup (132.412 ind/m3) and Pulau Besar (54.066 ind/m3). There were seven dominant species of copepods recorded in this study, namely Acrocalanus gracilis, Bestiolona similis, Euterpina acutifrons, Oithona nana, Oithona similis, Paracalanus aculeatus, and Paracalanus denudatus. Generally, this study has shown a notable relationship between local current circulation patterns and zooplankton distribution.

Long distance dispersal and oceanographic fronts shape the connectivity of the keystone sponge Phakellia ventilabrum in the deep northeast Atlantic

Little is known about dispersal in deep-sea ecosystems, especially for sponges, which are abundant ecosystem engineers. Understanding patterns of gene flow in deep-sea sponges is essential, especially in areas where rising pressure from anthropogenic activities makes difficult to combine management and conservation. Here, we combined population genomics and oceanographic modelling to understand how Northeast Atlantic populations (Cantabrian Sea to Norway) of the deep-sea sponge Phakellia ventilabrum are connected. The analysis comprised ddRADseq derived SNP datasets of 166 individuals collected from 57 sampling stations from 17 different areas, including two Marine Protected Areas, one Special Area of Conservation and other areas with different levels of protection. The 4,017 neutral SNPs used indicated high connectivity and panmixis amongst the majority of areas (Ireland to Norway), spanning ca. 2,500-km at depths of 99–900 m. This was likely due to the presence of strong ocean currents allowing long-distance larval transport, as supported by our migration analysis and by 3D particle tracking modelling. On the contrary, the Cantabrian Sea and Roscoff (France) samples, the southernmost areas in our study, appeared disconnected from the remaining areas, probably due to prevailing current circulation patterns and topographic features, which might be acting as barriers for gene flow. Despite this major genetic break, our results suggest that all protected areas studied are well-connected with each other. Interestingly, analysis of SNPs under selection replicated results obtained for neutral SNPs. The relatively low genetic diversity observed along the study area, though, highlights the potential fragility of this species to changing climates, which might compromise resilience to future threats.

Morphological change assessment of a coastal island in SE Bangladesh reveal high accumulation rates

It is essential to comprehend various morphological aspects, change dynamics, and stressors on the coastal environment in both contemporary and historical contexts. This study examines the potential for morphological changes in land use, erosion-sedimentation patterns, shoreline changes, and sediment accumulation on Sonadia Island in Southeast Bangladesh. To evaluate the extraordinarily high sediment accumulation phenomenon, the researchers used toposheets, historical maps, numerous satellite images, and field work observations. The investigation revealed that the shoreline of the island is subject to regular and rapid modifications. The island’s area coverage was 1.65 km2 in 1779, but it has grown 21 times to 36 km2 in 2021. From 1972 to 2021, the current study looks at land-use/land-cover changes on Sonadia Island, including mangrove (12.15 to 20.22 km2), tidal mudflats (6.69 to 4.63 km2), salt/shrimp fields (0 to 3.33 km2), dune (1.30 to 3.33 km2), beach sands (5.07 to 4.57 km2), and man-made forest (0 to 1.06 km2), as well as spatial changes in land. Between 1972 and 2021, erosion and sedimentation reached 1.35 km2 and 14.09 km2, respectively, resulting in a depositional rate of 0.29 km2 per year and an erosional rate of 0.03 km2 per year. The high accumulation rates are linked to shoreline activities such as mixing and reworking fluvial systems, longshore currents, tidal activity, strong waves, and seasonal current circulation patterns.

INTERPRETATION OF CURRENT AND TIDAL PATTERN AT SELANGOR RIVER, KUALA SELANGOR

Abstract. Tidal data has been used to determine long-term water level alterations. Tides are high-powered and notoriously hard to ascertain. Tidal analysis and prediction need substantial study with the requisite approaches, techniques, and tools in conjunction with weather parameters and natural calamities. TOtal TIde Solution (TOTIS) software, which is rooted in harmonic analysis, is one of the most often used software in Malaysia. This study aims to interpret the current circulation and tidal pattern at the Selangor River, Kuala Selangor, Selangor Darul Ehsan. A period of one-month data is retrieved via Valeport 740 Tide Gauge from tide gauge station, whereas the current data are retrieved via Valeport Current Meter 105, which are used to analysed. The latest updated data period for the tide gauge station utilised are based on the availability of data. Therefore, tides are predicted using 33 resolved constituents for two years, starting from January 2021 until December 2022. Tidal analysis generates tidal constituents, which are then used for tidal prediction. Root Mean Square Error (RMSE) and datum offset are used to evaluate software's output. It signifies that TOTIS software is trustworthy and reliable in terms of tidal analysis and prediction accuracy. The highest river current records with high speed occur during high tide phenomenon. The output data for magnitude of river current speed are derived satisfactorily with high precision. It aids in monitoring and analyse of an appropriate method to prevent or reduce additional river erosion.

Late Holocene current patterns in the northern Patagonian fjords recorded by sediment drifts in Aysén Fjord

Present-day circulation patterns in the southeastern Pacific Ocean are driven by the Antarctic Circumpolar Current, directing subantarctic surface water into the Patagonian fjords since at least the early Holocene. In this way, bottom current patterns in the area are regulated by the regional climate, although the complex bathymetry of the fjords has a significant impact as well. To understand the potential interplay of climate, seafloor topography and circulation patterns, we study the sedimentary infill of Aysén Fjord (~45°S) and reveal the first active sediment drifts in the region. These allow constraining the present-day circulation patterns in northern Patagonia and show an incoming (southward) as well as returning (northward) flow direction. While the general sedimentary evolution of the fjord (and thus also the sediment drifts) is climate-driven (i.e., it reflects variability in southern westerly wind strength), the onset of drift formation at ~3.7 ka does not seem to have originated from an abrupt change in regional climate. Instead, we propose that a megathrust earthquake described in paleoseismic records in the area could have resulted in subsidence of one (or more) of the many bathymetric highs in the Patagonian fjords, thus contributing to enhanced spilling of subantarctic water into the fjord. This study underscores the importance of multidisciplinary research to understand past and present bottom current circulation patterns and disentangle different possible feedback mechanisms.

Polychaete Diversity Related to Different Mesophotic Bioconstructions along the Southeastern Italian Coast

In the different mesophotic bioconstructions recently found along the Southeastern Italian coast, polychaetes have been proved to show high species richness and diversity, hitherto never investigated. In the present study, the species composition and functional role of polychaete assemblages were analysed; the updated key to identification of the Mediterranean species of genus Eunice was presented and some taxonomic issues were also discussed. On the total of 70 species Serpulidae and Eunicida were the dominant polychaetes. Facing similar levels of α-diversity, the polychaete assemblages showed a high turnover of species along the north-south gradient, clearly according to the current circulation pattern, as well as to the different bioconstructors as biological determinants. Indeed, Serpulidae were dominant on the mesophotic bioconstructions primarily formed by the deep-sea oyster Neopycnodonte cochlear, while the Eunicida prevailed on the mesophotic bioconstructions mainly built by scleractinians. Lastly, the record of Eunice dubitata was the first for the Mediterranean and Italian fauna and proved this species to be characteristic of mesophotic bioconstructions.

Variation of Seasonal Monsoon Wave-Driven Circulation Pattern in the Lee of Groyne in Kuala Nerus beach

Terengganu coast tend to dual monsoonal as presenting Northeast Monsoon (NEM) as a storm season and Southwest Monsoon (SWM) as a calm season. The area of interest is a groyne in Kuala Nerus, Terengganu on east part of Peninsular Malaysia. The use of numerical model was performed on the dual monsoon seasons with MIKE 21 modules (Spectral Wave FM and Flow Model Hydrodynamic FM modules). Two numerical model were set up according to the two season. The resulting model indicates, the current circulation pattern consisted of persistent eddy re-circulation in the lee of the groyne during both season. As the longshore current directed into the groyne, it deflected offshore resulting in rip current along the groyne. The rip current and incoming wave converge at the tip of the groyne and flow parallel to coastline before being projected onshore performing a re-circulation cell. During NEM, the model shows a clockwise re-circulation cell and counter-clockwise formation during SWM. The formation of the rip current and eddy circulation is associated with erosion event as the sediment transported offshore causing sediment shortage on the adjacent shore. The importance of this study can be a reference to any development of coastal defense monsoon dominated environment.

High resolution spatial distribution for the hexactinellid sponges Asconema setubalense and Pheronema carpenteri in the Central Cantabrian Sea

High resolution spatial distribution for the hexactinellid sponges Asconema setubalense and Pheronema carpenteri in the Central Cantabrian Sea

A New Seismic Stratigraphy in the Indian‐Atlantic Ocean Gateway Resembles Major Paleo‐Oceanographic Changes of the Last 7 Ma

AbstractThe exchange of water masses between the Indian Ocean and the Atlantic constitutes an integral interocean link in the global thermohaline circulation. Long‐term changes in deep water flow have been studied using seismic reflection profiles but the seismic stratigraphy was poorly constrained and not resolved for the time period from the late Miocene onward. Here we present results from International Ocean Discovery Program Site U1475 (Agulhas Plateau) located over a sediment drift proximal to the entrance of North Atlantic Deep Water into the Southern Ocean and South Indian Ocean. Site U1475 comprises a complete carbonate‐rich stratigraphic section of the last ~7 Ma that provides an archive of climate‐induced variations in ocean circulation. Six marker reflectors occurring in the upper 300 m of the drift are identified here for the first time. The formation of these reflectors is mainly due to density changes that are mostly caused by changes in biogenic versus terrigenous sediment deposition. Synthetic seismograms allow age assignments for the horizons based on biostratigraphy and magnetostratigraphy. Prominent reflectors are related to late Pleistocene glacial/interglacial variability, the middle and early Pleistocene transitions, and the onset of the northern hemisphere glaciation. A peculiar early Pliocene interval (~5.3–4.0 Ma) bounded by two reflectors is characterized by fourfold elevated sedimentation rates (>10 cm/kyr) and the occurrence of sediment waves. We argue that this enhanced sediment transport to the Agulhas Plateau was caused by a reorganization of the bottom current circulation pattern due to maximized inflow of North Atlantic Deep Water.

On the distribution and inventories of radionuclides in dated sediments around the Swedish coast

The activity concentrations and distribution of 137Cs, 238Pu, 239+240Pu, 241Am, and 210Pb was determined by the analysis of six sediment cores from the Baltic Sea and Kattegat. The chronology of the sediment cores has been used to evaluate the origin and time trend of the radionuclide sources in these sediments. The sediment cores were dated with a 210Pb model and the results were validated with fallout peaks, assumed to originate from the global nuclear weapons testing and the Chernobyl accident. Source identification, using the isotopic and radionuclide activity ratios, showed that the Chernobyl accident is the main source of 137Cs in the Baltic Sea; for 239+240Pu and 241Am the dominant source was shown to be fallout from nuclear weapons tests. For 238Pu and 241Am the Chernobyl accident had a significant impact on the direct fallout into the Baltic Proper, with up to a 65% contribution in the sediment slices dated to 1986. In these sediment slices the maximum activity ratios of 238Pu/239+240Pu and 241Am/239+240Pu were 0.314 ± 0.008 and 1.29 ± 0.06, respectively. The ratios clearly deviate from the corresponding ratios for global nuclear weapons fallout (around 0.028 and 0.54, respectively). Calculated inventories were 63–175 Bq·m−2 for 239+240Pu, 2.8–7.8 for 238Pu Bq·m−2 and 0.92–44.4 kBq·m−2 for 137Cs. Different fallout patterns for 137Cs and plutonium isotopes from the Chernobyl accident were confirmed through depth profiles analyses. The maximum inventory of 137Cs was observed in the Bothnian Sea, while Chernobyl-derived plutonium was found to be mostly present in Northern Baltic Proper. The radionuclides distribution in the depth profiles shows how contaminated water affects the sediment as it passes sampling stations according to the current circulation pattern in the Baltic Sea. Additionally, the effect of increased activity concentrations from of river discharges in the most contaminated area in the Bothnian Sea was observed.

Assessing water quality of the Chesapeake Bay by the impact of sea level rise and warming

The influence of sea level rise and warming on circulation and water quality of the Chesapeake Bay under projected climate conditions in 2050 were estimated by computer simulation. Four estuarine circulation scenarios in the estuary were run using the same watershed load in 1991-2000 period. They are, 1) the Base Scenario, which represents the current climate condition, 2) a Sea Level Rise Scenario, 3) a Warming Scenario, and 4) a combined Sea Level Rise and Warming Scenario. With a 1.6-1.9°C increase in monthly air temperatures in the Warming Scenario, water temperature in the Bay is estimated to increase by 0.8-1°C. Summer average anoxic volume is estimated to increase 1.4 percent compared to the Base Scenario, because of an increase in algal blooms in the spring and summer, promotion of oxygen consumptive processes, and an increase of stratification. However, a 0.5-meter Sea Level Rise Scenario results in a 12 percent reduction of anoxic volume. This is mainly due to increased estuarine circulation that promotes oxygen-rich sea water intrusion in lower layers. The combined Sea Level Rise and Warming Scenario results in a 10.8 percent reduction of anoxic volume. Global warming increases precipitation and consequently increases nutrient loads from the watershed by approximately 5-7 percent. A scenario that used a 10 percent increase in watershed loads and current estuarine circulation patterns yielded a 19 percent increase in summer anoxic volume, while a scenario that used a 10 percent increase in watershed loads and modified estuarine circulation patterns by the aforementioned sea level rise and warming yielded a 6 percent increase in summer anoxic volume. Impacts on phytoplankton, sediments, and water clarity were also analysed.

A Mid-Miocene erosional unconformity from the Durban Basin, SE African margin: A combination of global eustatic sea level change, epeirogenic uplift, and ocean current initiation

Erosional unconformity surfaces are key indicators for the variations in eustatic sea level, ocean dynamics and climatic conditions which significantly affect depositional environments of sedimentary successions. Using a dense grid of 2D seismic data, we present new evidence from a frontier basin, the offshore Durban Basin, of a mid-Miocene age erosional unconformity that can be correlated with analogous horizons around the entire southern African continental margin.In the Durban Basin, this unconformity is typified by the incision of a mixed carbonate-siliciclastic wedge and ramp margin by a series of submarine canyons. Epeirogenic uplift of southern Africa characterised this period, with erosion and sediment bypass offshore concomitant with increases in offshore sedimentation rates. Although epeirogenic uplift appears to be the dominant mechanism affecting formation of the identified sequence boundary, it is postulated that an interplay between global eustatic sea-level fall, expansion of the east Antarctic ice sheets, and changes in deep oceanic current circulation patterns may have substantially contributed to erosion during this period.

Historical gene flow constraints in a northeastern Atlantic fish: phylogeography of the ballan wrasse Labrus bergylta across its distribution range.

The distribution and demographic patterns of marine organisms in the north Atlantic were largely shaped by climatic changes during the Pleistocene, when recurrent glacial maxima forced them to move south or to survive in northern peri-glacial refugia. These patterns were also influenced by biological and ecological factors intrinsic to each species, namely their dispersion ability. The ballan wrasse (Labrus bergylta), the largest labrid fish along Europe's continental margins, is a target for fisheries and aquaculture industry. The phylogeographic pattern, population structure, potential glacial refugia and recolonization routes for this species were assessed across its full distribution range, using mitochondrial and nuclear markers. The existence of a marked population structure can reflect both recolonization from three distinct glacial refugia and current and past oceanographic circulation patterns. Although isolated in present times, shared haplotypes between continental and Azores populations and historical exchange of migrants in both directions point to a common origin of L. bergylta. This situation is likely to be maintained and/or accentuated by current circulation patterns in the north Atlantic, and may lead to incipient speciation in the already distinct Azorean population. Future monitoring of this species is crucial to evaluate how this species is coping with current environmental changes.

Modelling the long-term evolution of worst-case Arctic oil spills

We present worst-case assessments of contamination in sea ice and surface waters resulting from hypothetical well blowout oil spills at ten sites in the Arctic Ocean basin. Spill extents are estimated by considering Eulerian passive tracers in the surface ocean of the MITgcm (a hydrostatic, coupled ice-ocean model). Oil in sea ice, and contamination resulting from melting of oiled ice, is tracked using an offline Lagrangian scheme. Spills are initialized on November 1st 1980–2010 and tracked for one year. An average spill was transported 1100km and potentially affected 1.1 million km2. The direction and magnitude of simulated oil trajectories are consistent with known large-scale current and sea ice circulation patterns, and trajectories frequently cross international boundaries. The simulated trajectories of oil in sea ice match observed ice drift trajectories well. During the winter oil transport by drifting sea ice is more significant than transport with surface currents.

Hydrodynamic Modelling of Bidong Island Vicinity Waters

This paper explores the dynamic of meteorological forcing on current circulation pattern in the vicinity of Bidong using an unstructured flexible mesh hydrodynamic model. The forcings were wind, tides, temperature and salinity. The seasonal wind monsoon, mixed tides with dominant diurnal and tropical monsoon climate is characteristics of Bidong Island. We find that this area has different current circulation patterns in response to monsoon changes. It also experienced a small scale of island wake during NE monsoon. This island wake was generated by a strong northeasterly wind. We performed a series of numerical simulations based on three dominant factors in circulation, and evaluated the model using wind, tides and density. We investigated the wind-driven circulation and residual current. This study contributes to the debates on hydrodynamic of current circulation in vicinity of Bidong Island. Specifically, this study was conducted to understand the changes of currents by seasonal wind (NE monsoon and SW monsoon), temperature and salinity.

ANALISIS ARUS DAN SEBARAN SEDIMEN TERSUSPENSI DAMPAK TAMBANG TIMAH DI LAUT (KASUS PERAIRAN PULAU RANGSANG KABUPATEN KEPULAUAN MERANTI)

Utilization of marine natural resources at this current becoming one of the option thatis used by several Indonesian regions as motors of regional development. One of thenatural resources potential is tin mining. Tin mining over the ocean not only provideseconomic value, but also resulting negative impacts on marine waters. The alleged ofnegative impact is the increasing of suspended sediment in the waters due to leaching ofmining activities on the ship. Current circulation patterns that generated by tidal ofPulau Rangsang waters Regency of Meranti Islands, when the tide to ebb is heading tothe Southward and when the ebb to tide is heading to northward. The resultant ofcurrents circulation tend to align with the mainland of Pulau Topang. Suspendedsediment transport generated by ocean currents, showing the distribution of thesuspended sediment concentration of 0.08 kg/m3 or 80 ppm spreads about 2 km fromthe material source. Keywords : Ocean currents, Suspended sediment

Representing teleconnection patterns over Europe: A comparison of SOM and PCA methods

The main goal of this study is a comparison of two different methods of pattern recognition. The first, Principal Component Analysis (PCA), is a method frequently used in climatology. The second, Self Organizing Maps (SOM), is a relatively new and efficient method based on Artificial Neural Networks (ANN).In order to compare the two methodologies, two teleconnection patterns were chosen, the North Atlantic Oscillation (NAO), which mostly affects the climate of Western Europe, and the North Sea–Caspian Pattern (NCP), mainly affecting eastern Mediterranean and the Balkan Peninsula. The teleconnection patterns are studied for winter 500hPa geopotential height anomalies over the broader Europe area.The secondary objective of the study is to evaluate the ECHAM5/MPI General Circulation Model (GCM) in representing the two teleconnection patterns for a reference (1971–2000) and a future (2071–2100) period. The evaluation of the reference period is done comparing the simulated data to the NCEP/NCAR reanalysis data. The future period is studied to examine whether the current dominant circulation patterns change or not during the last 30years of the 21st century.According to the results, both PCA and SOM methodologies capture the main variability mode over the study area, represented by the NAO pattern, but SOM is capable of capturing even less pronounced patterns, such as the NCP. In the future simulations, the atmospheric circulation during winter seems to be more pronounced with stronger NAO and NCP teleconnection patterns.