Physical Oceanographic Processes Research Articles

A New Trajectory Clustering Method for Mining Multiple Periodic Patterns from Complex Oceanic Trajectories

Oceanic trajectories frequently exhibit multiple periodic patterns across various time intervals, e.g., tidal variations, mesoscale eddies, and El Niño events correspond to diurnal, seasonal, and interannual fluctuations in environmental factors. To explore hidden spatiotemporal multiple periodic behaviors in noisy ocean data, we propose a novel trajectory clustering method, namely DTID-STFC. It first identifies dense time intervals (DTIs) in which trajectories occur frequently. Subsequently, within each DTI, it utilizes spectral embedding to project trajectories onto a latent subspace and proposes three-way fuzzy clustering to obtain results. We evaluate the proposed method on simulated datasets and compare it with traditional and state-of-the-art trajectory clustering approaches. Experimental results indicate that it outperforms other methods across all five metrics. Moreover, when applying the DTID-STFC method to the analysis of mesoscale cyclonic eddies in the South China Sea and vessel data, it demonstrates more discernible results than traditional methods, and it aligns well with physical oceanographic processes. This proposed method offers valuable insights into identifying periodic behaviors from complex and noisy spatiotemporal oceanic trajectory data.

Formation mechanism of drift-moat contourite systems revealed by in-situ observations in the South China Sea

Contourite drifts are ubiquitous sedimentary features in the world′s oceans, and their formation are usually ascribed to sedimentation from contour currents. However, in-situ observations of contour currents and their associated sedimentary processes were inadequate. Here, we present mooring observation results from a drift-moat contourite system in the South China Sea to gain insight into its sediment dynamics and formation mechanism. We found that quasi-persistent contour currents develop in the moat, on and below the drift, yet subject to diverse physical oceanographic processes. High suspended sediment concentrations observed on the drift mainly occur in winter, induced by high levels of sediments transported by contour currents from Taiwan. In the moat, however, high suspended sediment concentrations are mostly caused by erosion of the moat wall during periods of strong tidal currents and low shear variance. Such results underscore the complexity of current patterns and sedimentary processes across various topographic units in the drift-moat contourite system. A novel formation mechanism of the contourite drift is thereby proposed, wherein sediment transport by contour currents brings materials for constructing the drift, while its formation is driven by near-critical reflection and upslope transport of sediments by tidal currents.

Spatio-Temporal Dynamics of Sediment Transport Pathways: Sand Apron Bars and Islands of Tokelau and Kiribati, Central Pacific

Although there is general agreement that global change will influence low-lying atoll islands, considerable uncertainty remains concerning the nature, rates, and causes of morphological change (or, conversely, the stability) of islands. As the net geomorphical product of sediment erosion, transport, and accumulation, islands are intimately tied to reef flat sedimentological processes. Recognizing the morphodynamical linkages between reef flats and islands, the purpose of this study is to examine the nature and controls on spatial and temporal variations in sediment transport pathways on reef flats and their relation to island planform changes or stability on atolls of Tokelau and Kiribati. GIS analysis of historical aerial images and high-resolution remote-sensing data capture patterns of reef flat change up to 72 years in duration with up to weekly temporal resolution. Data reveal how granular materials that make up bars and islands on reef flats respond to physical oceanographic processes via sedimentary-geomorphical change across temporal scales, from “instantaneous” impacts of cyclones or swell events to seasonal to multi-decadal shifts. Each of these shifts is manifest as migration of sediment of island beaches and bar forms, but the character varies markedly—bars form new islands, others erode and disappear; some changes are cyclic, others are directional, still others are hybrid; sediment can be transported lagoonward, oceanward, along the reef flat, or in combinations thereof; and migration rates reach up to 10 s of m/month. Although sea-level change likely plays a modulating role, much of the considerable spatial and temporal variability relates to differences in energy controlled by seasonal change in swell direction and climate shifts. Nonetheless, sedimentary response to these external forcings at any specific location also is shaped by local factors, such as trade wind-generated lagoonal waves and currents, atoll lagoon size and depth, margin width and orientation relative to waves, and autogenic processes such as attachment of migrating bars. Collectively, these influences shape the spatially and temporally heterogeneous sediment flux to and from islands, and thus the variable response of islands to ongoing sea-level change. Understanding such local influences is requisite to predictive understanding of how global change might impact these sensitive seascapes.

The Physical Oceanography of Ice-Covered Moons.

In the outer solar system, a growing number of giant planet satellites are now known to be abodes for global oceans hidden below an outer layer of ice. These planetary oceans are a natural laboratory for studying physical oceanographic processes in settings that challenge traditional assumptions made for Earth's oceans. While some driving mechanisms are common to both systems, such as buoyancy-driven flows and tides, others, such as libration, precession, and electromagnetic pumping, are likely more significant for moons in orbit around a host planet. Here, we review these mechanisms and how they may operate across the solar system, including their implications for ice-ocean interactions. Future studies should continue to advance our understanding of each of these processes as well as how they may act together in concert. This interplay also has strong implications for habitability as well as testing oceanic hypotheses with future missions.

Impacts of Basal Melting of the Totten Ice Shelf and Biological Productivity on Marine Biogeochemical Components in Sabrina Coast, East Antarctica

AbstractTo clarify the impacts of basal melting of the Antarctic ice sheet and biological productivity on biogeochemical processes in Antarctic coastal waters, concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA), inorganic nutrients, chlorophyll a, and stable oxygen isotopic ratios (δ18O) were measured from the offshore slope to the ice front of the Totten Ice Shelf (TIS) during the spring/summer of 2018, 2019, and 2020. Modified Circumpolar Deep Water (mCDW) intruded onto the continental shelf off the TIS and flowed along bathymetric troughs into the TIS cavity, where it formed a buoyant mixture with glacial meltwater from the ice shelf base. Physical oceanographic processes mostly determined the distributions of DIC, TA, and nutrient concentrations. However, photosynthesis and dilution by meltwater from sea ice and the ice shelf base decreased DIC, TA, and nutrient concentrations in surface water near the ice front. These causes also reduced the partial pressure of CO2 (pCO2) in surface water by more than 100 μatm with respect to mCDW in austral summer of 2018 and 2020, and the surface water became a strong CO2 sink for the atmosphere. Phytoplankton photosynthesis changed DIC and TA in a molar ratio of 106:16. Thus, pCO2 decreased mostly as a result of photosynthesis while dilution by glacial and sea ice meltwater had a small effect. The nutrient consumption ratio suggested that photosynthesis was stimulated by iron in the water column, supplied to the surface layer via buoyancy‐driven upwelling and basal ice shelf meltwater in addition to sea ice meltwater.

Spatio-temporal structures of satellite-derived water quality indicators along the Korean South Coast

The structure of 9-year time series data for Sea Surface Temperature (SST), Chlorophyll a (Chl-a) and Total Suspended Solids (TSS), derived from the Visible Infrared Imaging Radiometer Suite (VIIRS), was examined in this study. Authors found that there exists strong seasonality among the three variables with spatial heterogeneity along the Korean South Coast (KSC). In specific, SST was in phase with Chl-a, but out of phase with TSS by six months. A strong inversed spectral power with six-month phase-lag was found between Chl-a and TSS. This could be attributed to different dynamics and environmental settings. For example, Chl-a concentration seemed to have strong positive correlation with SST indicating typical seasonality of marine biogeochemical processes such as primary production; while a strong negative correlation between TSS and SST might have been influenced by changes in physical oceanographic processes, such as stratification and monsoonal wind-driven vertical mixing. In addition, the strong east–west heterogeneity of Chl-a suggests that the marine coastal environments are predominantly governed by distinct local hydrological conditions and human activities associated with land cover and land use, while the east–west spatial pattern revealed in TSS timeseries was associated with the gradient of tidal forcings and topographical changes keeping tidally induced resuspension low eastward.

Influence of upwelling on coral reef benthic communities: a systematic review and meta-analysis.

Highly competitive coral reef benthic communities are acutely sensitive to changes in environmental parameters such as temperature and nutrient concentrations. Physical oceanographic processes that induce upwelling therefore act as drivers of community structure on tropical reefs. How upwelling impacts coral communities, however, is not fully understood; upwelling may provide a natural buffer against climate impacts and could potentially enhance the efficacy of spatial management and reef conservation efforts. This study employed a systematic review to assess existing literature linking upwelling with reef community structure, and a meta-analysis to quantify upwelling impact on the percentage cover of coral reef benthic groups. We show that upwelling has context-dependant effects on the cover of hard coral and fleshy macroalgae, with effect size and direction varying with depth, region and remoteness. Fleshy macroalgae were found to increase by 110% on inhabited reefs yet decrease by 56% around one well-studied remote island in response to upwelling. Hard coral cover was not significantly impacted by upwelling on inhabited reefs but increased by 150% when direct local human pressures were absent. By synthesizing existing evidence, this review facilitates adaptive and nuanced reef management which considers the influence of upwelling on reef assemblages.

A Machine Learning-Based Correction Method for High-Frequency Surface Wave Radar Current Measurements

An algorithm based on a long short-term memory (LSTM) network is proposed to reduce errors from high-frequency surface wave radar current measurements. In traditional inversion algorithms, the radar velocities are derived from electromagnetic echo signals, with no constraints imposed by physical oceanographic processes. In this study, sea surface winds and tides are included in the LSTM algorithm to improve radar data. These physical factors provide the LSTM network with more oceanic information by which to constrain and improve its training efficiency. The results show that the domain-averaged root-mean-square errors of the radar-derived velocities are reduced from 0.22 to 0.09 m/s for the whole radar observation area. The overall correlation coefficient increases from 0.37 to 0.88. To provide a practical strategy for future field work, we conduct a set of sensitivity experiments, showing that the LSTM network based on one single point can be applied to other data points within a sub-domain.

Shelfbreak processes affecting acoustic propagation in a changing ocean

Fundamental physical oceanographic processes affecting sound speed fields and acoustic propagation have been studied in shelfbreak regions for some time. Integrated observations extending back to the 1990s have related acoustic propagation variability to basic thermohaline structure as well as physical oceanographic processes causing significant variability in sound speed fields. Key shelfbreak processes such as frontal wave propagation, eddy-Shelfbreak Jet interactions, and wind-driven motions will be described. The influence of ocean warming and climate change impacts on these processes will be outlined with emphasis on the Middle Atlantic Bight in the northeastern United States. The impacts of changes in both the atmospheric Jet Stream as well as the Gulf Stream on the Shelfbreak Front and Jet and implications for acoustic propagation will be presented.

Geologic processes in marine “muddy” sediments

Marine muds, or “muddy” sediments, represent a broad range of sediments containing a mix of clay and silt size components, often with some smaller amount of sand sized and larger material. Sediments characterized by these broad definitions comprise most of the modern global seafloor, except for areas proximal to terrigenous inputs, such as continental shelves and glacial margins, which can receive and retain a higher proportion of coarser sediment. Beyond the coastal zone, the distribution of marine sediments is driven by a combination of geological, biological, and physical oceanographic processes that themselves are a response to variations in environmental conditions (e.g., global climate, nutrient availability, tectonics, terrestrial erosion). At the local scale, sediment source variation, seafloor bathymetry, primary transport and near-bed currents, resuspension and reworking, and bioturbation contribute to the short- and long-term geologic nature of marine muds. The structure, quantitative compositional descriptions, and physical properties of marine muds from several environments will be compared and the techniques used to analyze them will be presented. New methods that may facilitate an improved understanding of the role and importance of muddy seafloor and shallow sub-seafloor sediments in influencing the acoustic environment will be highlighted.

Overview of the New England shelf break acoustics (NESBA) experiment

A joint ocean acoustics experiment was conducting at the southern edge of the New England Shelf in spring 2021 to investigate the sound propagation and scattering effects of physical oceanographic (PO) processes, marine geological (GEO) features, and biology (BIO) in the shelfbreak area. The experiment consisted of a network of sound sources, hydrophone arrays, and physical oceanography, and biological survey equipment was established. The environmental processes of particular interest include shelfbreak fronts, thermohaline intrusions, shelf water streamers, and internal waves, along with seafloor depressions and slopes, submarine canyons, and variable seabed properties (GEO), as well as fish schooling and shoaling (BIO). With fixed propagation paths, acoustic fluctuations can be correlated with environmental variations within the observation network with a temporal and spatial scales ranging from minutes to weeks and up to 30 km. One of the primary experiment objectives was on adaptive sampling and tracking of acoustic sensitivity “hot spots” to improve the real-time joint ocean acoustics and circulation modeling that was conducted on a research vessel in the field. This talk will review the design concept of this ocean acoustic network and provide an overview the experiment results. [Work supported by the Office of Naval Research.]

Biological–physical oceanographic coupling influencing particulate organic matter in the South Yellow Sea

Using total suspended matter (TSM), particulate organic carbon (POC), and particulate nitrogen data, this study investigated the potential vertical POC flux and transport in the South Yellow Sea (SYS). The biogenic production and resuspension fraction (i.e., the proportion of resuspended particles in TSM) were estimated using an ecosystem model and a vertical mixing model. They were verified against reported sediment trap and primary productivity data. The estimates of resuspension fraction showed substantial uncertainty of 50% in summer likely owing to the potential errors of model parameter estimation and the influence of other unexplored biophysical processes such as biological degradation, upwelling, and monsoons; however, the estimates of resuspension fraction showed less uncertainty in other seasons (<20%). Few previous studies have considered the specific influence of resuspension on the dynamics and budget of particulate organic matter (POM) in the SYS. This study proposed a reasonably simple and effective method to address this issue, which was applied to systematic examination of the variation of vertical POM flux with the change of coupled biological–physical oceanographic processes along the Subei coast and in the SYS central basin. The influence of horizontal transport from the Subei coast to the central basin may cause an overestimation of >10% of the resuspension fraction. It will be necessary to acquire additional field data covering a larger spatiotemporal scale to establish an integrated network of the SYS carbon budget.

Long-distance movements of Antarctic toothfish (Dissostichus mawsoni) as inferred from tag-recapture data.

Examining the causes and consequences of animal movement is fundamental to understanding the ecology of any species. This analysis focuses on Antarctic toothfish movements in the Southern Ocean as inferred from tagging data collected from 2001 to 2019 with a focus on the characteristics of long-distance movements, defined as an individual recaptured greater than 200 km from their release location. The results of this analysis indicate that while adult Antarctic toothfish are generally quite sedentary a small proportion (~7%) move long distances, consistent with findings from previous studies examining movements of toothfish. There appears to be no relationship between time at liberty and long-distance movements, no strong influence of sex and results indicate a distinct bias in the direction of long-distance travel from release to recapture towards a counter-clockwise direction. Frequency and scale of long-distance movements are likely influenced by localized physical oceanographic processes and life-history traits. Knowledge of these movements patterns remains highly important for stock assessments and the design of spatial and temporal fisheries management regimes.

Dense cold-water coral garden of Paragorgia johnsoni suggests the importance of the Mid-Atlantic Ridge for deep-sea biodiversity.

Mid‐ocean ridges generate a myriad of physical oceanographic processes that favor the supply of food and nutrients to suspension‐ and filter‐feeding organisms, such as cold‐water corals and deep‐sea sponges. However, the pioneering work conducted along the Mid‐Atlantic Ridge failed to report the presence of large and dense living coral reefs, coral gardens, or sponge aggregations. Here, we describe the densest, near‐natural, and novel octocoral garden composed of large red and white colonies of Paragorgia johnsoni Gray, 1862 discovered at 545–595 m depth on the slopes of the Mid‐Atlantic Ridge, in the Azores region. This newly discovered octocoral garden is a good candidate for protection since it fits many of the FAO criteria that define what constitutes a Vulnerable Marine Ecosystem. The observations described here corroborate the existence of a close relationship between the octocoral structure and the ambient currents on ridge‐like topographies, providing new insights into the functioning of mid‐ocean ridges' ecosystems. The ubiquitous presence of biogenic and geological topographies associated with mid‐ocean ridges, which could act as climate refugia, suggests their global importance for deep‐sea biodiversity. A better understanding of the processes involved is, therefore, required. Our observations may inspire future deep‐sea research initiatives to narrow existing knowledge gaps of biophysical connections with benthic fauna at small spatial scales along mid‐ocean ridges.

Hydrodynamic influences on sedimentology and geomorphology of nearshore parts of carbonate ramps: Holocene, NE Yucatán Shelf, Mexico

ABSTRACTAlthough carbonate ramps are ubiquitous in the geologic record, the impacts of oceanographic processes on their facies patterns are less well constrained than with other carbonate geomorphic forms such as isolated carbonate platforms. To better understand the role of physical and chemical oceanographic forces on geomorphic and sedimentologic variability of ramps, this study examines in-situ field measurements, remote-sensing data, and hydrodynamic modeling of the nearshore inner ramp of the modern northeastern Yucatán Shelf, Mexico.The results reveal how sediment production and accumulation are influenced by the complex interactions of the physical, chemical, and biological processes on the ramp. Upwelled, cool, nutrient-rich waters are transported westward across the ramp and concentrated along the shoreline by cold fronts (Nortes), westerly regional currents, and longshore currents. This influx supports a mix of both heterozoan and photozoan fauna and flora in the nearshore realm. Geomorphically, the nearshore parts of this ramp system in the study area include lagoon, barrier island, and shoreface environments, influenced by the mixed-energy (wave and tidal) setting. Persistent trade winds, episodic tropical depressions, and winter storms generate waves that propagate onto the shoreface. Extensive shore-parallel sand bodies (beach ridges and subaqueous dune fields) of the high-energy, wave-dominated upper shoreface and foreshore are composed of fine to coarse skeletal sand, lack mud, and include highly abraded, broken and bored grains. The large shallow lagoon is mixed-energy: wave-dominated near the inlet, it transitions to tide-dominated in the more protected central and eastern regions. Lagoon sediment consists of Halimeda-rich muddy gravel and sand. Hydrodynamic forces are especially strong where bathymetry focuses water flow, as occurs along a promontory and at the lagoon inlet, and can form subaqueous dunes.Explicit comparison among numerical models of conceptual shorefaces in which variables are altered and isolated systematically demonstrates the influences of the winds, waves, tides, and currents on hydrodynamics across a broad spectrum of settings (e.g., increased tidal range, differing wind and wave conditions). Results quantify how sediment transport patterns are determined by wave height and direction relative to the shoreface, but tidal forces locally control geomorphic and sedimentologic character. Similarly, the physical oceanographic processes acting throughout the year (e.g., daily tides, episodic winter Nortes, and persistent easterly winds and waves) have more impact on geomorphology and sedimentology of comparable nearshore systems than intense, but infrequent, hurricanes. Overall, this study provides perspectives on how upwelling, nutrient levels, and hydrodynamics influence the varied sedimentologic and geomorphic character of the nearshore areas of this high-energy carbonate ramp system. These results also provide for more accurate and realistic conceptual models of the depositional variability for a spectrum of modern and ancient ramp systems.

Observations of the variability of the New England shelf break by shipboard echosounders

The New England Shelf Break is a dynamic region where warm salty slope water meets with colder less saline shelf water to form a distinct front. The position and shape of the front is modified by a range of processes on differing temporal and spatial scales. While seasonal changes are well documented, the influence of shorter time scale processes throughout the water column are less well understood. Of interest is the influence of meso-scale physical oceanographic processes such as meanders in the Gulf Stream and warm core rings and eddies. From March to June 2021 five cruises to the New England Shelf Break were conducted as part of the ONR Task Force Oceans New England Shelf Break Acoustics Experiments. The shipboard broadband echo sounders on the R/V Neil Armstrong were used to ensonify the front during each of these five cruises. Significant changes were observed, especially during the transit of a warm core eddy through the study area. Groups of scatterers in the study area were targeted by Deep-See (a broadband tow sled) and a broadband echo sounder equipped REMUS 600 to enable ensonification of individual targets to aide in acoustic identification of biology at the shelf break front.

Surface pH Record (1990–2013) of the Arabian Sea From Boron Isotopes of Lakshadweep Corals—Trend, Variability, and Control

AbstractAtmospheric CO2 rise in post‐industrial era has resulted in decline in surface ocean pH, commonly known as “ocean acidification (OA),” which has become a threat to marine calcifiers. Instrumental records of ocean pH and its reconstruction utilizing boron isotope (δ11B) composition of corals demonstrate a long‐term OA trend characterized by large spatio‐temporal variability in both Pacific and Atlantic oceans. However, no such record exists to elucidate long‐term OA trend of the Indian Ocean. We report the first sub‐annually resolved pH record (1990–2013) from the Arabian Sea based on δ11B measurements on Porites coral from Lakshadweep coral reefs. This pH record is characterized by large variability ranging from 7.93 to 8.65 with no long‐term discernable trend. The long‐term declining trend expected from the ∼50 ppm increase in atmospheric CO2 during the coral growth interval appears to be obscured by large surface pH variability in the Arabian Sea. Our investigation reveals that physical oceanographic processes for example, upwelling, downwelling and convective mixing modulated by El Niño‐Southern Oscillation (ENSO) largely control surface pH variability and masked expected long‐term OA trend resulting from anthropogenic CO2 rise. Combining the model‐based predictions of increase in frequency and amplitude of ENSO events in a future warming scenario and the observed ENSO dependency of surface water pH, we predict more frequent and large pH variability (“pH extremes”) in this region. Such pH extremes and their occurrences might be critical for the resilience and adaptability of corals and other calcifiers in Arabian Sea and other similar oceanic settings elsewhere.

Seasonal responses of nutrient to hydrology and biology in the southern Yellow Sea

Seasonal nutrient dynamics regulated by hydrological and biological variables in the southern Yellow Sea (SYS) were studied based on the datasets collected during four cruises: spring (April 28-May 10, 2014), summer (August 17-September 22, 2015), autumn (November 7–17, 2014) and winter (January 13-February 1, 2016). In the present study, by dividing the study area into three distinct current-dominated subregions based on T-S distribution, cluster analysis, and principal components analysis (PCA), we revealed that the response mechanisms of nutrients to physical and biological processes were important. Among all factors, the physical processes, mainly including the Yellow Sea Cold Water Mass (YSCWM) onset, the Changjiang (Yangtze) Diluted water (CDW) and Taiwan Warm Current (TWC) intrusion and the Yellow Sea Warm Current (YSWC) invasion, were the principal driving force, which significantly changed the inherent balance of nutrient structure. Meanwhile, biological depletion was also a significant factor, especially in the stratified seasons, even though its impact on the nutrient structure could be balanced by vigorous water exchange or vertical mixing. The regional variation of nutrient regime and the regulatory mechanism behind it were revealed at the same time. The coastal area showed strong signs of potential P limitation as a result of excessive dissolved inorganic nitrogen (DIN) entering via terrestrial runoff and anthropogenic activities. The 32 °N transect, which is adjacent to the boundary of the SYS and the East China Sea (ECS), showed varying hydrological features due to the strong intrusion of CDW and TWC. Therefore, P or Si were the main limiting factor for the development of algal biomass. The central study area possessed a comparatively stable water column with the specific existence of the YSCWM present at the bottom, thus acting as a potential nutrient pool. Hence, we hypothesized that the offshore side of the study area tended to be more P and N co-limited, whereas the nutrient cycles in the nearshore side showed significant seasonal and regional variations, which corresponded to the change in physical oceanographic processes and algal biomass.

Spatial variability of the ichthyoneuston around oceanic islands at the tropical Atlantic

Oceanic tropical waters are characteristically oligotrophic. However, current-topography interaction around oceanic islands promotes bio-physical processes, which may enrich surface waters. The ichthyoneuston assemblage at three areas around oceanic islands in the tropical Atlantic was investigated. The aim was to evaluate if the ichthyoneuston was influenced by physical oceanographic processes, such as possible mechanisms of plankton retention promoted by the presence of the islands. Samplings were performed by 20 min long diurnal and nocturnal 500-μm plankton net hauls using a David-Hempel Catamaran at two transections in each area (Saint Peter and Saint Paul's archipelago, Fernando de Noronha archipelago, and Rocas Atoll). The transections were composed by three stations and were located at opposite sides of the archipelagos (windward and leeward sides of the archipelago). A total of 131 larvae and 3027 eggs, belonging to 16 families and 28 species were collected. Higher densities of eggs were found at the leeward side, which indicates the occurrence of a retention mechanism or spawning at this side. Higher densities of larvae were found at Fernando de Noronha, especially during the nocturnal period. Only one species, Ceratoscopelus warmingii, co-occurred at the three islands. Fernando de Noronha was highlighted as the area with the higher density, abundance and species richness. The waters around this island were positively correlated with chlorophyll-a, which indicates a higher availability of food items and stimulates the selection of this area as a favorable spot for reproduction and early nursery zone. This work highlighted the importance of the relation between abiotic factors and the distribution of fish eggs and larvae inhabiting the neustonic layer around South Atlantic oceanic islands, showing that favorable conditions, e.g. higher phytoplanktonic biomass, may be of fundamental importance to the spawning by adult individuals.

Numerical Simulation Studies about the Resonance of Tsunami Waves in Selected Gulfs and Ports along the South West Coast of India (SWCI)

The tsunami of December 26, 2004 was an eye-opener which exposed the need for establishing a tsunami warning system in the Indian Ocean. Immediately after the tsunami of 2004, Government of India subsequently established a Tsunami Warning Centre in Hyderabad. The numerical modelling of tsunami inundation and run-up also gained momentum in India. Besides inundation and run-up there are several other physical oceanographic processes which contributes in shaping tsunami characteristics along the coast. The source of tsunami generation is prominent in determining run-up values. Historical records show the generation of tsunamigenic earthquakes from Sumatra, North Andaman and Car Nicobar in the Bay of Bengal and Makran in the Arabian Sea. Though the numerical modelling studies has been reasonably carried out for the main land coast, no study has been exclusively carried out for understanding the amplification pattern occurring in gulfs and ports in the Arabian sea. Tsunami waves entering the ports and gulfs can lead to different amplification patterns. At this juncture, this paper investigates the pattern of amplification occurring along four representative sectors along the west coast namely Gulf of Kutch, Gulf of Khambhat, Mangalore port and Cochin inlet. The simulation results show trivial amplification in Gulf of Kutch and Gulf of Khambhat. The studies of numerical simulation suggest that the amplification factor depends on several other factors like orientation of the coast, coastal geometry of bays and gulfs, near shore bathymetry and depth inside gulfs and ports. How to cite this article: Praveen SS. Numerical Simulation Studies about the Resonance of Tsunami Waves in Selected Gulfs and Ports along the South West Coast of India (SWCI). J Adv Res Appl Mech Compu Fluid Dyna 2020; 4(1): 1-5. DOI: https://doi.org/10.24321/2349.7661.202001