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The effects of an inlet inertial jet on the thermal blending of hot and cold heat transfer fluid (molten salt) for a single tank sensible thermal energy storage system are studied using numerical simulations. The simulations show the evolution of the initial stratified layer (thermocline) for a temperature difference of 300 K with a corresponding Atwood number (At) of 0.066. Three diffuser arrangements are investigated: a flat plate solid diffuser, a coaxial ring diffuser with a solid center, and a proposed hemispherical diffuser. The thermal stratifications are examined by a mathematical model named Ideal stratification index (ISI). It is observed that the buoyancy-driven mixing is minimum for the hemispherical diffuser, and the resulting thermocline is 6% better compared to alternative diffusers at 27 l/min. Additionally, the working of the proposed diffuser is demonstrated via experiments with a saline-freshwater combination. These results reveal that the single tank thermocline storage performance can be improved for higher charging/discharging rates using hemispherical diffusers.

For the first time the vertical variation in light quality in the global ocean is quantified with a single parameter--the hue angle (αE, in degree) in chromaticity of downwelling irradiance. For oceanic waters, αE is ~140° at surface, but it becomes ~230° at the bottom of the euphotic zone; αE changes rapidly near the surface, and we term this layer of rapid change in light quality as chromocline, analogous to the thermocline or pycnocline in oceanography. The 3-D variations in light quality are further highlighted with data from satellite ocean color measurements, where global distributions of αE for depths of 99%, 37%, and 1% of surface photosynthetically available radiation (PAR) are presented. As an example to demonstrate the importance to consider the change in light quality, the relationship between the light quality and the ratio of phytoplankton absorbed light to PAR is presented where this ratio may vary by a factor of 3 or more under different chlorophyll-a concentrations; otherwise, the ratio would be constant vertically. We advocate quantitative measurement and report the light quality in the upper ocean with such a single and objective parameter to accompany the routine measurement and report the light intensity, which will greatly improve our understanding of light-related processes and further bridge ocean optics and oceanography.

Like most continental shelves, the Gulf of Lions in the northwestern Mediterranean Sea provides multiple ecological services and is subject to multiple natural and anthropogenic pressures. In this context, this marine habitat must be described to monitor its evolution and ensure its protection. We used carbon and nitrogen stable isotope analysis to describe the structure of the benthic food web. Two sampling campaigns, corresponding to two contrasting situations in terms of water stratification, were carried out in 2018. One in April when the water column was still well mixed and the annual peak of phytoplankton production had already occurred, the other in September after several months of thermal stratification and low primary productivity. Results revealed that the structure of the food web changed in terms of range, extent and degree of trophic diversity. Between the two sampling dates, isotopic niches of the taxa remained evenly distributed but the niche space shrunk. Temporal changes in stable isotope compositions were greater for active suspension feeders, surface deposit feeders and their direct predators than for other functional groups feeding deep in the sediment or hunting a wider range of prey. The increase in nitrogen isotope ratios of primary consumers is either the result of a fasting effect due to reduced food availability or a change in feeding behavior due to reduced digestibility of primary food sources.

The open ocean region of southern Bay of Bengal (BoB) (~ 5° N–10° N; 87° E–97° E) is characterized as the region of low chlorophyll-a concentration (

A 17 kWhth packed bed thermal energy storage (PBTES) system for concentrated solar power application (CSP) has been investigated by using a two-phase energy model. The PBTES system used in this stu...

The Indian Ocean presents two distinct climate regimes. The north Indian Ocean is dominated by the monsoons, whereas the seasonal reversal is less pronounced in the south. The prevailing wind pattern produces upwelling along different parts of the coast in both hemispheres during different times of the year. Additionally, dynamical processes and eddies either cause or enhance upwelling. This paper reviews the phenomena of upwelling along the coast of the Indian Ocean extending from the tip of South Africa to the southern tip of the west coast of Australia. Observed features, underlying mechanisms, and the impact of upwelling on the ecosystem are presented. In the Agulhas Current region, cyclonic eddies associated with Natal pulses drive slope upwelling and enhance chlorophyll concentrations along the continental margin. The Durban break-away eddy spun up by the Agulhas upwells cold nutrient-rich water. Additionally, topographically induced upwelling occurs along the inshore edges of the Agulhas Current. Wind-driven coastal upwelling occurs along the south coast of Africa and augments the dynamical upwelling in the Agulhas Current. Upwelling hotspots along the Mozambique coast are present in the northern and southern sectors of the channel and are ascribed to dynamical effects of ocean circulation in addition to wind forcing. Interaction of mesoscale eddies with the western boundary, dipole eddy pair interactions, and passage of cyclonic eddies cause upwelling. Upwelling along the southern coast of Madagascar is caused by the Ekman wind-driven mechanism and by eddy generation and is inhibited by the Southwest Madagascar Coastal Current. Seasonal upwelling along the East African coast is primarily driven by the northeast monsoon winds and enhanced by topographically induced shelf breaking and shear instability between the East African Coastal Current and the island chains. The Somali coast presents a strong case for the classical Ekman type of upwelling; such upwelling can be inhibited by the arrival of deeper thermocline signals generated in the offshore region by wind stress curl. Upwelling is nearly uniform along the coast of Arabia, caused by the alongshore component of the summer monsoon winds and modulated by the arrival of Rossby waves generated in the offshore region by cyclonic wind stress curl. Along the west coast of India, upwelling is driven by coastally trapped waves together with the alongshore component of the monsoon winds. Along the southern tip of India and Sri Lanka, the strong Ekman transport drives upwelling. Upwelling along the east coast of India is weak and occurs during summer, caused by alongshore winds. In addition, mesoscale eddies lead to upwelling, but the arrival of river water plumes inhibits upwelling along this coast. Southeasterly winds drive upwelling along the coast of Sumatra and Java during summer, with Kelvin wave propagation originating from the equatorial Indian Ocean affecting the magnitude and extent of the upwelling. Both El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) events cause large variability in upwelling here. Along the west coast of Australia, which is characterized by the anomalous Leeuwin Current, southerly winds can cause sporadic upwelling, which is prominent along the southwest, central, and Gascoyne coasts during summer. Open-ocean upwelling in the southern tropical Indian Ocean and within the Sri Lanka Dome is driven primarily by the wind stress curl but is also impacted by Rossby wave propagations. Upwelling is a key driver enhancing biological productivity in all sectors of the coast, as indicated by enhanced sea surface chlorophyll concentrations. Additional knowledge at varying levels has been gained through in situ observations and model simulations. In the Mozambique Channel, upwelling simulates new production and circulation redistributes the production generated by upwelling and mesoscale eddies, leading to observations of higher ecosystem impacts along the edges of eddies. Similarly, along the southern Madagascar coast, biological connectivity is influenced by the transport of phytoplankton from upwelling zones. Along the coast of Kenya, both productivity rates and zooplankton biomass are higher during the upwelling season. Along the Somali coast, accumulation of upwelled nutrients in the northern part of the coast leads to spatial heterogeneity in productivity. In contrast, productivity is more uniform along the coasts of Yemen and Oman. Upwelling along the west coast of India has several biogeochemical implications, including oxygen depletion, denitrification, and high production of CH4 and dimethyl sulfide. Although weak, wind-driven upwelling leads to significant enhancement of phytoplankton in the northwest Bay of Bengal during the summer monsoon. Along the Sumatra and Java coasts, upwelling affects the phytoplankton composition and assemblages. Dissimilarities in copepod assemblages occur during the upwelling periods along the west coast of Australia. Phytoplankton abundance characterizes inshore edges of the slope during upwelling season, and upwelling eddies are associated with krill abundance. The review identifies the northern coast of the Arabian Sea and eastern coasts of the Bay of Bengal as the least observed sectors. Additionally, sustained long-term observations with high temporal and spatial resolutions along with high-resolution modelling efforts are recommended for a deeper understanding of upwelling, its variability, and its impact on the ecosystem.

In this study, daily outgoing longwave radiation (OLR) product is used to detect the atmospheric intraseasonal oscillation (ISO) in the eastern tropical Indian Ocean (TIO). A 50–80-day ISO is identified south of the equator, peaking in boreal winter and propagating eastward. The mechanisms underneath are investigated using observational data and reanalysis products. The results suggest that the 50–80-day atmospheric ISO is enhanced by ocean dynamic processes during December–January. Monsoon transition in October–November causes large wind variability along the equator. Equatorial sea surface height/thermocline anomalies appear off Sumatra due to the accumulative effects of the wind variability, leading the atmospheric 50–80-day ISO by ~ 5–6 weeks. The wind-driven ocean equatorial dynamics are reflected from the Sumatra coast as downwelling oceanic Rossby waves, which deepen the thermocline and contribute to the SST warming in the southeastern TIO, affecting local atmospheric conditions. It offers insights into the role of ocean dynamics in the intensification of 50–80-day atmospheric ISOs over the eastern TIO and explains the seasonal peak of the eastward-propagating ISO during boreal winter. These results have implications for intraseasonal predictability.

After its maturity, El Nino usually decays rapidly in the following summer and evolves into a La Nina pattern. However, this was not the case for the 2018/19 El Nino event. Based on multiple reanalysis data sets, the space-time evolution and triggering mechanism for the unusual second-year warming in late 2019, after the 2018/19 El Nino event, are investigated in the tropical Pacific. After a short decaying period associated with the 2018/19 El Nino condition, positive sea surface temperature anomalies (SSTAs) re-intensified in the eastern equatorial Pacific in late 2019. Compared with the composite pattern of El Nino in the following year, two key differences are evident in the evolution of SSTAs in 2019. First, is the persistence of the surface warming over the central equatorial Pacific in May, and second, is the re-intensification of the positive SSTAs over the eastern equatorial Pacific in September. Observational results suggest that the re-intensification of anomalous westerly winds over the western and central Pacific, induced remotely by an extreme Indian Ocean Dipole (IOD) event, acted as a triggering mechanism for the second-year warming in late 2019. That is, the IOD-related cold SSTAs in the eastern Indian Ocean established and sustained anomalous surface westerly winds over the western equatorial Pacific, which induced downwelling Kelvin waves propagating eastward along the equator. At the same time, the subsurface ocean provided plenty of warm water in the western and central equatorial Pacific. Mixed-layer heat budget analyses further confirm that positive zonal advection, induced by the anomalous westerly winds, and thermocline feedback played important roles in leading to the second-year warming in late 2019. This study provides new insights into the processes responsible for the diversity of El Nino evolution, which is important for improving the physical understanding and seasonal prediction of El Nino events.

Thermocline sensible heat storage (SHS) systems are usually utilized in parabolic trough solar power systems. Liquid lead–bismuth eutectic (LBE) is a potential heat transfer medium for SHS systems, but its influences on the performances of SHS systems are rarely studied. In this study, a simulation model of thermocline SHS tank using liquid LBE as the heat transfer fluid is established, and the influences of initial cold and hot LBE temperatures on the operation and mechanical performances of the tank are estimated. The results reveal that when the liquid LBE is used as the heat transfer fluid, the SHS tank can operate stably. The initial cold LEB temperature has almost no influence on both the total heat storage and heat release durations of the tank, while the initial hot LBE temperature has proportional relationships with the total heat storage and heat release durations. The heat storage performance as well as the heat release behavior of the tank can be improved by increasing the initial cold LBE temperature, or by decreasing the initial hot LBE temperature. The peak maximum mechanical stress of the tank can be decreased by increasing the initial cold LBE temperature, or by decreasing the initial hot LBE temperature.

Satellite-tracking of adult bumphead sunfish, Mola alexandrini, revealed long-distance latitudinal migration patterns covering thousands of kilometers. Horizontal and vertical movements of four bumphead sunfish off Taiwan were recorded with pop-up satellite archival tags in 2019–2020. Two individuals moved northward and traveled to Okinawa Island and Kyushu, Japan and two moved southwards; crossing the equator, to Papua New Guinea and New Caledonia. During daytime, bumphead sunfish descended below the thermocline and ascended to mixed layer depths (MLD) during nighttime. The N–S migrants, however, demonstrated different habitat utilization patterns. Instead of using prevailing currents, the northward movements of sunfish cohorts exhibited extensive use of mesoscale eddies. Fish in anticyclonic eddies usually occupied deeper habitats whereas those in cyclonic eddies used near-surface habitats. On northward excursions, fish spent most of their time in regions with high dissolved oxygen concentrations. Southward movement patterns were associated with major currents and thermal stratification of the water column. In highly stratified regions, fish stayed below the thermocline and frequently ascended to MLD during daytime either to warm muscles or repay oxygen debts. These results for bumphead sunfish present important insights into different habitat use patterns and the ability to undergo long-distance migrations over varying spatial-temporal scales and features.

In the Gulf of Alaska, commercially harvested fish species utilize habitats dominated by red tree corals (Primnoa pacifica) for shelter, feeding, and nurseries, but recent studies hint that environmental conditions may be interrupting the reproductive lifecycle of the corals. The North Pacific has experienced persistent and extreme thermal variability in recent years and this pattern is predicted to continue in coming decades. Recent discovery of deep-water emerged coral populations in Southeast Alaska fjords provided opportunity for detailed life-history studies and comparison to corals in managed habitats on the continental shelf. Here we show that sperm from deep colonies develops completely, but in shallow colonies, sperm development is prematurely halted, likely preventing successful production of larvae. We hypothesize that the divergence is due to differing temperature regimes presently experienced by the corals. Compared to deep populations below the thermocline, shallow populations experience much greater seasonal thermal variability and annual pulses of suspected near-lethal temperatures that appear to interrupt the production of viable gametes. The unique opportunity to comprehensively study emerged populations presently affected by thermal stress provides advance warning of the possible fate of deep corals in the Gulf of Alaska that will soon experience similar ocean conditions.

The thermocline-sea surface temperature (SST) feedback is the most important component of the Bjerknes feedback, which plays an important role in the development of the air-sea coupling modes of the Indian Ocean. The thermocline-SST feedback in the Indian Ocean has experienced significant decadal variations over the last 40 a. The feedback intensified in the late twentieth century and then weakened during the hiatus in global warming at the early twenty-first century. The thermoclidal variations of feedback are similar in these two regions, there are still differences in the underlying mechanisms. The decadal variations of feedback in the southeastern Indian Ocean are dominated by variations in the depth of the thermocline, which are modulated by equatorial zonal wind anomalies. Whereas the decadal variation of feedback in the southwestern Indian Ocean is mainly controlled by the intensityne-SST feedback is most prominent in the southeastern and southwestern Indian Ocean. Although the deca of upwelling and thermocline depth in winter and spring, respectively. The upwelling and thermocline depth are both affected by wind stress curl anomalies over the southeastern Indian Ocean, which excite anomalous Ekman pumping and influence the southwestern Indian Ocean through westward propagating Rossby waves.

In the present study, heat redistribution in the Tropical Indian Ocean (TIO) associated with the prolonged La Nina events during 1958–2017 is examined using reanalysis/observations. It is found that the prolonged La Nina forcing strengthened the east–west thermocline gradient in the equatorial Indian Ocean and propelled the eastward extension of thermocline ridge of the Indian Ocean (TRIO) from its climatological location of southwestern TIO. The cyclonic winds over the southeastern TIO and the associated upwelling Rossby waves are primarily driving the TRIO intensification and its eastward extension. Anomalous subsurface warming, thermocline deepening, and the associated increase in the upper ocean heat content and sea-level in the eastern equatorial Indian Ocean, southeastern TIO and Bay of Bengal (BoB) are found to be the characteristic features of the prolonged La Nina events. Cross equatorial Sverdrup transport near the eastern boundary during the prolonged La Nina events has increased the heat content of BoB and is found to be a pathway of Pacific water entering the north Indian Ocean.

Our study explores the variability of chlorophyll a and phycocyanin as well as the taxonomic and functional structure of phytoplankton in epilimnetic and metalimnetic strata regarding the main environmental features of the water column. The maximum phytoplankton pigment concentrations are located differently depending on the type of thermal stratification and light availability. In general, there were three situations observed during the summer stratification: the euphotic zone did not extend to the thermocline and the highest chlorophyll concentration developed above the thermocline level, at the bottom of the euphotic zone (type I); the euphotic zone reached beyond the thermocline, and the maximum chlorophyll concentration occurred above the thermocline (type II); or the euphotic zone was much greater than the thermocline depth and the peak phytoplankton density was located below the thermocline (type III). In metalimnetic samples, the most dominant cyanobacteria belonged to the Reynolds Functional Groups (RFG) H1, S1, and Lo; their occurrence differed depending on the types of light and thermal regimes. It was assumed that vertical heterogeneity affects the ecological status assessment based on phytoplankton. Calculating the two applied indices (TI index and Q index) based on metalimnetic and epilimnetic data (as opposed to only epilimnetic data) yielded worse ecological status in > 70% of cases.

Time-varying sources of upwelling waters off the coast of northern Peru are analyzed in a Lagrangian framework, tracking virtual particles backwards in time for 12 months. Particle trajectories are calculated with temperature, salinity and velocity fields from a hindcast spanning 1988–2007, obtained with an eddy-resolving (1/12∘) global configuration of the Nucleus for European Modelling of the Ocean (NEMO) ocean model. At 30 and 100 m, where coastal upwelling rates exceed 50 m month−1, particles are seeded at monthly intervals in proportion to the upwelling rate. Ensemble maps of particle concentration, age, depth, temperature, salinity and density reveal that a substantial but variable fraction of the particles upwelling off Peru arrives via the Equatorial Undercurrent (EUC). Particles follow the EUC core within the depth range 125–175 m, characterized by temperatures ∘C, salinities in the range 34.9–35.2 and densities of σθ=25.5–26.5. Additional inflows are via two slightly deeper branches further south from the main system, at around ≈3 and ≈8∘ S. Averaged across the hindcast, annual-mean percentages of particles upwelling at 30 m (100 m) associated with the EUC vary from 57.4 % (52 %) at 92∘ W to 19.2 % (17.9 %) at 165∘ W. Considerable interannual variability in these percentages reveals that more of the Peruvian upwelling can be traced back to the EUC during warm events, such as El Niño. In contrast, upwelling waters are of more local origin during cold events such as La Niña. Despite weaker EUC transport during El Niño, relative flattening of the equatorial thermocline brings the EUC upwelling waters much closer to the Peruvian coast than under neutral or La Niña conditions. Annually averaging EUC transport at specific longitudes, a notable negative-to-positive transition is evident during the major El Niño/La Niña events of 1997/99. On short timescales, a degree of longitudinal coherence is evident in EUC transport, with transport anomalies at 160∘ W evident at the Galápagos Islands (92∘ W) around 30–35 d later. It is concluded that the Peruvian upwelling system is subject to a variable EUC influence, on a wide range of timescales, most notably the interannual timescale of El Niño–Southern Oscillation (ENSO). Identifying this variability as a driver of shifts in population and catch data for several key species, during the study period, these new findings might inform sustainable management of commercially important fisheries off northern Peru.

Fishes typically occupy a species-specific temperature range, with their occupied depth being related to the lake’s temperature profile. When a fish’s preferred temperature range coincides with the thermocline, the location of their preferred thermal habitat is influenced by the rise and fall of internal waves, leading to possible changes in fish depth. These internal waves are common in large, stratified lakes, yet we do not know how they affect the spatial distribution and behavior of freshwater fishes. We conducted nighttime hydroacoustic surveys in a large, deep embayment of a large thermally stratified lake to observe whether pelagic fish respond to vertical oscillations of the thermocline caused by internal waves. The coldwater pelagic fish in our study (primarily cisco, Coregonus artedi) typically occupied a narrow vertical band approximately 5–8 m thick and temperatures between 10.8 ± 0.8–13.6 ± 1.6 °C (fishes sized 106–500 mm), just below the thermocline (centered around 15–17 °C). Importantly, the upper bound of fish depth varied in response to vertical thermocline movements associated with internal waves, suggesting fish respond to changes in their physical environment on timescales commensurate with basin-scale internal wave periods (hours to days), to remain within their preferred thermal habitat. Dissolved-oxygen levels were typically above avoidance thresholds of these fish, thus not likely exerting a strong influence on fish location. Our findings emphasize the need to account for internal waves when designing hydroacoustic and netting surveys, as thermocline movements can influence where fish are located.

Subduction associated with mesoscale eddies is an important but difficult-to-observe process that can efficiently export carbon and oxygen to the mesopelagic zone (100–1000 dbar). Using a novel BGC-Argo dataset covering the western North Pacific (20–50∘ N, 120–180∘ E), we identified imprints of episodic subduction using anomalies in dissolved oxygen and spicity, a water mass marker. These subduction patches were present in 4.0 % (288) of the total profiles (7120) between 2008 and 2019, situated mainly in the Kuroshio Extension region between March and August (70.6 %). Roughly 31 % and 42 % of the subduction patches were identified below the annual permanent pycnocline depth (300 m vs. 450 m) in the subpolar and subtropical regions, respectively. Around half (52 %) of these episodic events injected oxygen-enriched waters below the maximum annual permanent thermocline depth (450 dbar), with >20 % occurring deeper than 600 dbar. Subduction patches were detected during winter and spring when mixed layers are deep. The oxygen inventory within these subductions is estimated to be on the order of 64 to 152 g O2/m2. These mesoscale events would markedly increase oxygen ventilation as well as carbon removal in the region, both processes helping to support the nutritional and metabolic demands of mesopelagic organisms. Climate-driven patterns of increasing eddy kinetic energies in this region imply that the magnitude of these processes will grow in the future, meaning that these unexpectedly effective small-scale subduction processes need to be better constrained in global climate and biogeochemical models.

In areas of intensive ship traffic, ships pass every 10 min. Considering the amount of ship traffic and the predicted increase in global maritime trade, there is a need to consider all types of impacts shipping has on the marine environment. While the awareness about, and efforts to reduce, chemical pollution from ships is increasing, less is known about physical disturbances, and ship-induced turbulence has so far been completely neglected. To address the potential importance of ship-induced turbulence on, e.g., gas exchange, dispersion of pollutants, and biogeochemical processes, a characterisation of the temporal and spatial scales of the turbulent wake is needed. Currently, field measurements of turbulent wakes of real-size ships are lacking. This study addresses that gap by using two different methodological approaches: in situ and ex situ observations. For the in situ observations, a bottom-mounted acoustic Doppler current profiler (ADCP) was placed at 32 m depth below the shipping lane outside Gothenburg harbour. Both the acoustic backscatter from the air bubbles in the wake and the dissipation rate of turbulent kinetic energy were used to quantify the turbulent wake depth, intensity, and temporal longevity for 38 ship passages of differently sized ships. The results from the ADCP measurements show median wake depths of 13 m and several occasions of wakes reaching depths > 18 m, which is in the same depth range as the seasonal thermocline in the Baltic Sea. The temporal longevity of the observable part of the wakes had a median of around 10 min and several passages of > 20 min. In the ex situ approach, sea surface temperature was used as a proxy for the water mass affected by the turbulent wake (thermal wake), as lowered temperature in the ship wake indicates vertical mixing in a thermally stratified water column. Satellite images of the thermal infrared sensor (TIRS) onboard Landsat-8 were used to measure thermal wake width and length, in the highly frequented and thus major shipping lane north of Bornholm, Baltic Sea. Automatic information system (AIS) records from both the investigated areas were used to identify the ships inducing the wakes. The satellite analysis showed a median thermal wake length of 13.7 km (n=144), and the longest wake extended over 60 km, which would correspond to a temporal longevity of 1 h 42 min (for a ship speed of 20 kn). The median thermal wake width was 157.5 m. The measurements of the spatial and temporal scales are in line with previous studies, but the maximum turbulent wake depth (30.5 m) is deeper than previously reported. The results from this study, combined with the knowledge of regional high traffic densities, show that ship-induced turbulence occurs at temporal and spatial scales large enough to imply that this process should be considered when estimating environmental impacts from shipping in areas with intense ship traffic.

An eddy-resolving four-dimensional variational (adjoint) data assimilation and state estimate was constructed for the low- to mid-latitude Pacific, Indian Oceans, and South China Sea based on the framework of “Estimating the Circulation and Climate of the Oceans (ECCO)”. It is named as the Two Oceans One Sea State Estimate (TOOSSE). It fits a model to a number of modern observations of 2015–2016, including the Argo float temperature and salinity, satellite altimetric sea surface anomalies, by adjusting initial temperature and salinity, sea surface boundary conditions, and background diapycnal diffusivities. In total, ∼50% of the original model-data misfits have been eliminated, and the estimated state agreed well with a variety of independent observations at meso- to large scales, and on the intra-seasonal to interannual timescales. Mesoscale variability is systematically strengthened in TOOSSE and closer to observations than that without data assimilation, which is especially evidenced by the improved simulation of the mesoscale tropical instability waves (TIWs). Adjustments to ocean surface forcing parameters exhibit both large and frontal/mesoscale structures, and the magnitude reach 20%–100% of the first guesses; the adjustments to diapycnal diffusivity exhibit an obvious elevation (decrement) in (below) the thermocline in the equatorial band. The results indicate that TOOSSE represents a dynamically and thermodynamically consistent ocean state estimate of the 2015–2016 Indo-Pacific Ocean, and can be widely utilized for regional process studies.

The thermal energy storage system is a pivotal system for solar thermal plants for improving reliability. The stability in the thermocline is more significant to clarify and improve the performance of thermal energy storage tank which legitimately shows the quality of the thermocline. In this stability analysis investigation, the modern engineering energy storage material concrete was used as a filler material for high-temperature thermal energy storage applications as a result of the intrinsic properties. A comprehensive laminar and k-e turbulent flow energy transport model accounts for the heat transfer fluid and filler material with adiabatic and non-adiabatic conditions using LTNE (Local Thermal Non-Equilibrium model). The axial, radial, and diagonal temperature differences were identified which was used to calculate the stability of the thermocline. A thermal energy storage tank size of 1 m height and 0.250 m diameter with a 0.030 m size of filler material packed with an average porosity of 0.3 for the storage capacity of 150 kWh/m3 is used for solar process heating applications considered for the present study. The thermocline stabilities are performed with Reynolds numbers, Re varied from 1 to 3000. It is found that the Re = 1 provides better stability in the axial and radial direction as well as diagonal than other Reynolds number. It is observed that Re = 1 provides superior discharging efficiency for nearly 5.84 hrs which is highly suitable for solar process heating applications and the discharging efficiency consistently drops, when Re increases from 1 to 3000. The wall condition of the tank and velocity of the heat transfer fluid is highly disturbing the thermocline in the radial direction and it creates a ‘spike’ profile in the axial direction. Based on the newly introduced stability scale, the effective length of packing and timing to achieve stability is identified for H/D = 4. From that result, the top and bottom layer of the thermocline tank porosity is also found which is used to decide the porosity of the packed bed distributors. The identified porosity for the top and bottom distributors in the ɛ = 0.3 thermal energy storage tank is less than 0.3 is more suitable for provide the uniform flow in the tank.

Solar hot water storage tanks with mantle heat exchangers are widely used in balcony wall-mounted solar heating system in China. The thermal behaviour of a novelty mantle solar water tank with vertical inlet and outlet water tubes has been investigated both experimentally and numerically. Dimensionless parameter can well characterize the stratification of water and thermocline dynamics in the water tank. In the discharging mode, as the dimensionless time increases, the thermocline thickness gradually increases, and the mixing in the water tank intensifies. The dimensionless exergy gradually decreases with the increase of the dimensionless time.

We simulated bottom resuspension events in Lake Erie, using a coupled three-dimensional hydrodynamic and water quality model. Key parameters in the model, including critical bottom shear stress ( τ cr ) and resuspension rate (α) were calibrated and validated by comparing the model output to observations. These included total suspended solid (TSS) concentrations in the bottom boundary layer (RMSE = 0.74 mg L -1 ) and water column (RMSE = 0.81 mg L -1 ), and to time series of acoustic backscatter signal (R2 > 0.8) and turbidity (R2 ≈ 0.4) from long-term moorings near the lakebed in 2008–09 and 2013. Signals from phytoplankton, in spring and summer, caused discrepancies between modeled TSS and the observed turbidity data. Although common practice, we show that literature-based or field-observed critical shear stress should not be directly applied in large-scale Reynolds-averaged sediment model as this will likely underestimate resuspension. In agreement with the literature, the model reproduced more frequent and intensive surface-wave driven resuspension in the shallow regions ( τ c ) were comparable with those due to surface waves ( τ w ). However, on the north-shore of the eastern basin, τ c often predominated over τ w . We simulated thermocline motion, including up- and down-welling events and swashing of the internal Poincare wave, to contribute to τ c in the central basin and form nepheloid layers.

Tropical Pacific sea surface temperatures (SSTs) are a critical component of the global climate system with oceanic and atmospheric teleconnections through meridional and latitudinal heat transport. Understanding the climate drivers and dynamics of this region enables a better understanding of global climate. Orbital scale climate drivers for eastern and western Pacific SSTs have been studied; however, SSTs and thermocline structure have not been studied in the central equatorial Pacific (CEP). Studying temperature dynamics in the CEP upper water column can help determine which mechanisms control SST and thermocline structure and test previously proposed hypotheses. Here, I present CEP SST and subsurface temperature records from the Line Islands (ML1208-17PC) that span the last 380,000 years. Using two species of foraminifera, G. ruber and G. tumida, I respectively generated Mg/Ca based SST and subsurface temperature records and compared them to published records from the equatorial Pacific. This comparison indicates an expanded west pacific warm pool (WPWP) during interglacial periods but no expansion of the eastern Pacific cold tongue during glacial periods. Based on the thermocline depth proxy, the thermocline was deeper in glacial periods and shallower in interglacial periods. Cross-spectral analysis demonstrates which climate drivers are the likely forcings for CEP SST and thermocline behavior. The CEP SSTs are distinct from those to the east or the west as they are not directly driven by CO2 or insolation at orbital frequencies; instead, the CEP SST record is linked to subsurface temperature at eccentricity and obliquity bands. However, changes in thermocline conditions at the CEP are potentially driven by CO2 and Antarctic temperature changes. This study agrees and supports previous studies that indicate deeper thermocline depths in glacials and shallower depths in interglacials.

The paper presents the results of hydrological studies which we carried out on the shelf of the Peter the Great Bay of the Sea of Japan in July – August 2012, July – August 2017, August 2019 and August 2021. We have analyzed spatial variability of temperature and sound velocity fields, peculiar to the region, on the basis of hydrological CTD-data and the results of long-term measurements with anchored vertical thermostrings. In the course of measurements, we registered the following typhoons during theirpassageoff the coast of the Primorsky Territory of Russia: Bolaven (August 28–29, 2012), Noru (August 7–8, 2017), Krosa (August 16, 2019), Mirinae (August 7–9, 2021), Lupit (August 8–9, 2021), Omais (August 10–11, 2021). A significant change in the hydrological situation in the bay under the influence of extreme external factors is shown. Up to three mild thermoclines are observed in the bay in calm meteorological conditions. Its are located at depths of 8–15 m, 30–35 m, and 45–60 m in some cases, a thermocline with a large gradient was located at depths of 30–40 m. The temperature difference in the thermocline formed under the influence of typhoons was approximately 12–15°C per 10 m of depth. Apparently, the intensification of waves and surge of heated surface water in the Peter the Great Bay, caused by strong southerly and southwesterly winds, lead to the appearance of a pronounced near-bottom underwater sound channel. Since such changes affect the propagation of acoustic signals, they are especially important to study when working with autonomous underwater objects, their positioning and communicating with them., В статье представлены результаты гидрологических исследований на шельфе залива Петра Великого Японского моря в июле – августе 2012, июле – августе 2017, августе 2019 и августе 2021 годов. Пространственная изменчивость полей температуры и скорости звука, характерная для региона, проанализирована по результатам гидрологических CTD-зондирований и долговременных измерений заякоренными вертикальными термогирляндами. В ходе измерений было зарегистрировано прохождение тайфунов Болавен (28–29 августа 2012 года), Нору (7–8 августа 2017 года), Кроса (16 августа 2019 года), Мирина (7–9 августа 2021 года), Лупит (8–9 августа 2021 года), Омаис (10–11 августа 2021 года) у побережья Приморья Российской Федерации. Показано значительное изменение гидрологической ситуации в заливе под воздействием экстремальных внешних факторов. В спокойных метеорологических условиях в заливе наблюдается до трех слабовыраженных термоклина, расположенных на глубинах 8–15 м, 30–35 м и 45–60 м. Во время прохождения тайфунов три термоклина объединяются в один мощный на глубине примерно 50–60 м, а в некоторых случаях термоклин с большим градиентом находился на глубинах 30–40 м. Перепад температуры в термоклине, сформированным под действием тайфунов, составил примерно 12–15°C на 10 м глубины. По-видимому, усиления волнения и нагон прогретой поверхностной воды в заливе Петра Великого, вызванные сильными южными и юго-западными ветрами, приводят к появлению ярко выраженного придонного подводного звукового канала. Поскольку такие изменения влияют на распространение акустических сигналов, их особенно важно исследовать при работе с автономными подводными объектами, осуществлении их позиционирования и связи с ними.