Water Temperature Distribution Research Articles

Estimation and Comparative Analysis on the Distribution Functions of Air and Water Temperatures in Korean Coastal Seas

The distribution shapes of air and water temperatures are basic and essential information, which determine the frequency patterns of their occurrence. It is also very useful to understand the changes in long-term air and water temperatures with respect to climate change. The typical distribution shapes of air and water temperatures cannot be well fitted using widely used/accepted normal distributions because their shapes show multimodal distributions. In this study, Gaussian mixture distributions and kernel distributions are suggested as the more suitable models to fit their distribution shapes. Based on the results, the tail shape exhibits different patterns. The tail is long in higher temperature regions of water temperature distribution and in lower temperature regions of air temperature distribution. These types of shape comparisons can be useful to identify the patterns of long-term air and water temperature changes and the relationship between air and water temperatures. It is nearly impossible to identify change patterns using only mean-temperatures and normal distributions.

Juvenile coho salmon track a seasonally shifting thermal mosaic across a river floodplain

Summary Seasonal variation in river water levels creates a shifting mosaic of habitat conditions associated with variables such as water temperature, chemistry and prey availability to consumers. Previous work has shown that fishes can exploit spatial variation in water temperature, but less is known about how they respond to shifts in the spatial arrangement of habitat conditions through time. Juvenile coho salmon (Oncorhynchus kisutch) are the numerically dominant fish species in many southwest Alaskan streams, which exhibit seasonal variation in water level and temperature due to changes in precipitation and snowmelt. We assessed the degree to which juvenile coho salmon exploit the associated shifting mosaic of water temperature by monitoring the spatial distribution of water temperatures and juvenile coho salmon in the lake‐influenced reaches of a southwest Alaskan stream. We also monitored the diets of juvenile coho salmon relative to the spatial distribution of prey taxa. Juvenile coho salmon exhibited two scales of movement to track spatiotemporal variation in habitat conditions. First, over the course of 6 weeks, individuals moved among off‐channel units, tracking shifts in the location of warm water habitat caused by receding water level. Second, individuals moved at diel time scales, foraging on benthic macroinvertebrates in the cold thalweg of the stream at night and then digesting prey in warmer off‐channel habitats during the day. Seasonally asynchronous variation in water temperature among off‐channel habitat units produced portfolio effects in habitat conditions, such that coho salmon had continual access to warm habitat for digestion despite its ephemeral availability at discrete locations. Our study demonstrates that behavioural thermoregulation by juvenile fishes can be important throughout the growing season and is not restricted to ephemeral events such as resource pulses or heat stress. Our results have implications for the conservation of highly connected, heterogeneous landscapes, and their ability to support economically and ecologically important species such as coho salmon.

Surface wave effects on water temperature in the Baltic Sea: simulations with the coupled NEMO-WAM model

Coupled circulation (NEMO) and wave model (WAM) system was used to study the effects of surface ocean waves on water temperature distribution and heat exchange at regional scale (the Baltic Sea). Four scenarios—including Stokes-Coriolis force, sea-state dependent energy flux (additional turbulent kinetic energy due to breaking waves), sea-state dependent momentum flux and the combination these forcings—were simulated to test the impact of different terms on simulated temperature distribution. The scenario simulations were compared to a control simulation, which included a constant wave-breaking coefficient, but otherwise was without any wave effects. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwelling’s. Overall, when all three wave effects were accounted for, did the estimates of temperature improve compared to control simulation. During the summer, the wave-induced water temperature changes were up to 1 °C. In northern parts of the Baltic Sea, a warming of the surface layer occurs in the wave included simulations in summer months. This in turn reduces the cold bias between simulated and measured data, e.g. the control simulation was too cold compared to measurements. The warming is related to sea-state dependent energy flux. This implies that a spatio-temporally varying wave-breaking coefficient is necessary, because it depends on actual sea state. Wave-induced cooling is mostly observed in near-coastal areas and is the result of intensified upwelling in the scenario, when Stokes-Coriolis forcing is accounted for. Accounting for sea-state dependent momentum flux results in modified heat exchange at the water-air boundary which consequently leads to warming of surface water compared to control simulation.

Prediction of desalination time of saemangeum reservoir

AbstractThe Saemangeum Reservoir is located on the western coast of the Republic of Korea and is embanked by a 33.9 km sea dike. The Saemangeum River Basin consists of the Mankyeong and Dongjin river basins, which have an immediate influence on the hydrodynamic characteristics of the Saemangeum Reservoir. The objectives of this study are to simulate a series of temporal and spatial distributions of water temperature and salinity to estimate the required time for desalination of the Saemangeum Reservoir and to suggest possible timing for the first agricultural water supply. To achieve this objective, a hydrodynamic numerical model is calibrated and five conditions are considered for estimating the required desalination period. The simulated period for desalination is 2.0 ‐ 2.5 years considering the conditions of percolated seawater and leached salt from the reclaimed areas, while the period of desalination is expected to take more than five years considering the conditions of salt elution from the benthic layer. Under the conditions that rural water can mostly be supplied from the surface layer of the Saemangeum Reservoir, it is expected to supply water for agricultural use in three years after the desalination of the surface layer of the reservoir. Copyright © 2016 John Wiley & Sons, Ltd.

Recycling Irrigation Reservoir Stratification and Implications for Crop Health and Production

AbstractRecycling irrigation reservoirs (RIRs) are an emerging aquatic ecosystem and water resource of global significance. This study investigated the vertical distribution of water temperature, dissolved oxygen (DO), and pH in eight RIRs at two nurseries each in Virginia and Maryland from 2011 to 2014. Monomictic thermal stratification was observed from April to October in all RIRs, despite their shallow depths (0.75‐3.89 m). The strongest stratification had a top‐bottom temperature difference of 21.53°C. The top‐bottom temperature difference was positively correlated with water column depth, air temperature, and daily light integral (p < 0.05). Wind speed did not impact the thermal stratification, likely due to their relatively small surface areas. Thermal stratification affected the vertical distribution of DO and pH. The top‐bottom differences in DO and pH were greater during stratification periods than nonstratification periods. Water pH in all RIRs was higher at the top than at the bottom with the greatest difference of 4.16 units. Discovery and characterization of thermal stratification in RIRs helps understand water quality dynamics in this novel ecosystem and promote safe and productive water reuse for irrigation. Specifically, water withdrawal depths should be adjusted according to variations in temperature, DO, and pH during the stratification and nonstratification periods to mitigate pathogen risk and improve water treatment efficacy and crop production.

The Attenuation of Retroreflective Signatures on Surface Soils

Soil parameters such as water potential, temperature, organic matter (om), and particle size distribution influence biological activity and collectively define the state of soils, yet these properties are typically described through time-intensive, ground-based sampling efforts. To improve our understanding of soils through stand-off sensing techniques, Light Detection and Ranging was used to monitor the signature of retroreflective beads embedded in polymeric agents on four soils. Our goal was to generate probability density functions (PDFs) for stochastic predictions of the persistence of this signature through time. Our findings showed that the PDFs of the reflected signal between target and background soils became nearly indistinguishable after five months and that OM, nitrogen content, cation exchange capacity, and pH related to signature decline. This approach, while developed using polymer-bound retroreflectors, will serve as a framework where a signature-emitter is left in or on soil and differentially influenced by terrain, weather, and soil processes.

Effect of friction stir welding on hydrogen content of ISO 3183 X80M steel

The influence of Friction Stir Welding (FSW) on hydrogen content of ISO 3183 X80M high strength steel was evaluated for several welding conditions, including dry and underwater environments. The diffusible and non-diffusible (residual) hydrogen were measured by a hot extraction method that involved adaptation of ISO 3690 and AWS A4.3 (arc welding process) standards. It was found that FSW does not significantly influence the hydrogen content under dry conditions even when the steel surface is oxidized. A slight increase in both diffusible and residual hydrogen content was observed for underwater FSW. However, the total hydrogen content is significantly less than the minimum allowable hydrogen concentration in similar steels. In addition, the low tool temperature reached during underwater FSW suggests the absence of hydrogen generation by water molecule decomposition. This is in according with the temperature distribution in water obtained by finite element method simulation of this welding process. Therefore, FSW is a feasible welding process and offers important advantages in terms of hydrogen control when it is compared to conventional fusion welding processes.

Distribution of Water Temperature and Common Squid Todarodes pacificus Paralavae around Korean Waters in 2013, 2014

Field observation for oceanic conditions and paralarvae of the common squid, Todarodes pacificus in Korean waters were sampled with the Bongo net (diameter: 60 cm, mesh size: ) by using oblique tow method with the oceanographic research vessel (Tamgu 12 and Tamgu 20) around Korean waters (middle of the Yellow Sea, northern part of the East China Sea, East Sea) in 2013 and 2014 was carried out. The observation in the Yellow Sea and the northern part of the East China Sea was done in August, 2013 and in the East Sea it was repeated at seven times from June, 2013 to September, 2014. The paralarvae in August of 2013 was not found in the Yellow Sea and one paralarvae was found in the northern part of the East China Sea. In the East Sea, 39 paralarvae during whole observation period were found, mantle length of paralarvae was from 1.7 to 13.5 mm. Surface water temperature in the Yellow Sea was , and cold water mass lower than was occupied in the deep layer than 30 m. In the northern part of the East China Sea, surface water temperature was , and higher water temperature above was found in deeper than 50 m. In the East Sea, optimum temperature for survival, , was existed shallower than 75 m.

Modelagem do regime térmico de um reservatório tropical de abastecimento público, Juiz de Fora, MG, Brasil

Water temperature changes and the dynamics of thermal stratification of an aquatic ecosystem directly influence physical, chemical and biological processes. Due to disturbances in these environments, such as climate change and multiple water uses, studies which employ modeling are important to support emergency decision-making and future planning. In this context, this study evaluated the thermal behavior of the water supply reservoir of Sao Pedro, located in the city of Juiz de Fora, MG, using mathematical modeling with the IPH-ECO model to evaluate the surface temperature of water, based on meteorological and hydrological data representing the forcing and boundary conditions, respectively. The modeling of the thermal system showed a significant correlation between predicted and observed values, characterizing the reservoir as a homogeneous environment. The simulations indicated that the tributary contribution determines the pattern of spatio-temporal distribution of water temperature in the reservoir, limiting or regulating the variability of its temperature.

Heat transfer to supercritical water in a vertical tube with concentrated incident solar heat flux on one side

A solar tower power plant with supercritical water as a heat-transfer medium in the central receiver is potentially one of the most promising solar thermal power technologies due to its high solar-to-electric efficiency. In this paper, the heat transfer of supercritical water in a vertical tube of a solar tower receiver has been investigated. A 3D mathematical model has been developed to investigate the distribution of heat flux in the circumferential direction of a circular tube heated by concentrated incident solar flux on one side. The RNG k–ε model with the standard wall function is employed to describe the turbulent flow of water from a liquid-like state to a gas-like state, and the results are validated with experimental data. For supercritical water in a tube heated on one side by concentrated incident solar heat flux, the maximum wall temperature is located on the sunward outside wall where the incident heat flux is at a maximum. In the pseudo-critical flow region, due to the drastic turbulent diffusion of supercritical water, the temperature distribution of the supercritical water in the tube is evenly distributed at the same flow cross section. To avoid deterioration in the heat transfer of supercritical water, the relation between the threshold incident solar heat flux and mass flux for the supercritical water has been provided. Furthermore, the Nusselt correlation which can be used to predict heat transfer coefficient of the vertical tube heated non-uniformly on one side by concentrated solar flux has been confirmed.

Relationship between Irrigation Conditions and Distribution of Paddy Water Temperature under Continuous Irrigation with Running Water

Relationship between Irrigation Conditions and Distribution of Paddy Water Temperature under Continuous Irrigation with Running Water

낙동강유역에서 위성영상을 이용한 보 건설 전후 수온의 계절변화

Abstract In this study we were to explore the seasonal variation of water temperature distributions before and after weir construction at Gumi, Chilgok, Gangjung(Goryung), Dalsung in the Nakdong River using Landsat satellite images. Relationship between in-situ water temperature and radiance values of Landsat-5, 7, 8 satellite images showed high correlation. Seasonal variation of water temperature in Nakdong River showed that the fluctuation ranges of water temperature before weir construction were larger than those after weir construction. This indicated that the variation of water temperature is due to the difference of heat storage volume by weir construction and dredging work. In particular, the water temperature after weirs construction in autumn was 4-8 times lower than that before weirs construction. Water temperature after weir construction decreased in spring and summer at the downstream of Gumi weir and Gangjung(Goryung) weir, and the upstream of Dalsung weir. In autumn and winter, the water temperature after weir construction increased in the upstream and downstream of the whole weirs except upstream of Gumi weir. Relationship between water temperature and meteorological elements (air temperature, wind speed, sunshine, radiation) showed high correlation of above 94% in air temperature, and then radiation was high correlation before and after 65%.

Evaluation of Influence of Header Design on Water Flow Characteristics in Window Cavity with CFD

Water flow window is a multi-glazing system with a flowing water layer in the cavity. The water flows in a closed loop which is connected to a double-pipe heat exchanger. Two headers with evenly distributed openings are located at the top and bottom ends of the window cavity. Water flow and temperature distribution in the cavity are studied with different header designs in this numerical study. It is found that the change in opening size or interval will affect the local distribution of temperature and flow velocity around the headers. But their effect on the overall system performance is insignificant.

A stepwise model of direct contact membrane distillation for application to large-scale systems: Experimental results and model predictions

A model of mass and heat transfer in direct contact membrane distillation (DCMD) is presented. The distributions of water flux, temperature, and concentration in membrane module channels are modeled to provide cumulative water flux and outlet temperatures and concentrations. The membrane distillation coefficient (MDC)—a membrane-specific mass transfer coefficient—for a well-characterized PTFE membrane was shown to be accurately modeled as a constant value. The MDC was used with a stepwise modeling approach, in which the membrane area is discretized into multiple steps, to provide the distribution of process variables parallel to the membrane surface. A new generalized spacer modeling method was used to account for the presence of complex woven spacers in the flow channels, addressing a significant gap in the DCMD modeling literature. Model predictions showed good agreement with experiments in co-current and counter-current flow modes for different operating conditions and membrane sizes. The stepwise modeling approach was shown to be necessary for providing accurate mass and heat transfer predictions for large-scale DCMD modules, providing a useful tool for the design of large-scale DCMD systems.

Estuarine circulation in the Taranto Seas.

The Taranto basin is a shallow water marine system in the South of Italy characterized by the presence of a lagoon environment together with a semi-enclosed bay connected to the Ionian Sea. This marine system experienced over the last few decades strong biochemical pollution and environmental degradation, and it is considered a hotspot study site for economic, ecological and scientific reasons. The aim of this study was to examine, on an annual temporal scale and with high spatial resolution, the main hydrodynamical processes and transport scales of the system by means of a 3D finite element numerical model application, adopting the most realistic forcing available. The model allowed us to assess the role played by baroclinic terms in the basin circulation, describing its estuarine nature. In particular, the main features of water circulation, salinity and temperature distribution, water renewal time and bottom stress were investigated. Our results allowed us to equate this system dynamic to that of a weakly stratified estuary, identifying the main driving sources of this mechanism. The vertical stratification over the whole year was proved to be stable, leading to a dual circulation flowing out on the surface, mainly through Porta Napoli channel, and inflowing on the bottom mainly through Navigabile channel. This process was responsible also for the renewal time faster on the bottom of the Mar Piccolo basin than the surface. Due to the great importance of the Taranto basin for what concerns sediment pollution, also the effect of currents in terms of bottom stress was investigated, leading to the conclusion that only in the inlets area the values of bottom stress can be high enough to cause erosion.

The effects of extremely hot summer 2010 on water temperature and oxygen distribution in Karelian lakes

Presented are the results of the analysis of interannual variability of the thermal regime of two Karelian lakes. The data of long-term observations in Lake Syamozero (1953–2011) and Lake Vendyurskoe (2007–2013) enabled analyzing and comparing the range of the natural interannual variability of water temperature and its values in hot summer 2010. Considered are the effects of extreme conditions in summer 2010 on the formation of thermal stratification and on the dissolved oxygen regime in the lakes. It is revealed that the global warming may increase the probability of deep anoxia development in shallow lakes in the temperate zone.

Three dimensional experimental and numerical investigations into hydrate dissociation in sandy reservoir with dual horizontal wells

In this study, both three dimensional experimental and numerical investigations of hydrate dissociation have been carried out by depressurization in conjunction with warm water stimulation using dual horizontal wells. Hydrate has been synthesized in the porous sediment in a CHS (Cubic Hydrate Simulator). The results of gas and water production, hydrate dissociation, and temperature distribution by numerical simulation are in good agreement with the experimental results. The results show that hydrate dissociation evolves by means of ablation with double-moving boundary. One dissociation interface moves from the injection well to the neighboring regions, and the other dissociation interface spreads from the boundary to the central reservoir. The assessment of the energy ratio shows that the depressurization in conjunction with warm water stimulation using dual horizontal wells is a promising method for hydrate dissociation. Sensitivity analyses show that raising the injection temperature causes a sharply decline of energy ratio, although it increases the gas production rate at a certain time. Additionally, reducing the intrinsic permeability of the reservoir can decrease the energy ratio and increase the time for the completion of hydrate dissociation.

Characterisation of water temperature variability within a harbour connected to a large lake

Abstract Many coastal embayments in the Laurentian Great Lakes have highly variable temperatures due to pronounced movements of the thermocline in the nearshore zone. As an example, we document the diverse thermal regimes in Toronto Harbour, which is also the site of some of the most extensive fish habitat restoration activities in Lake Ontario. Toronto Harbour is characterised by considerable thermal variability as a result of diurnal heat fluxes and large amplitude movements of the thermocline of Lake Ontario. During the ice-free period from April–November 2013, an array of benthic and surface temperature loggers were deployed to obtain the spatio-temporal distribution of water temperatures. Complementary measurements of stratification were made in Lake Ontario at a site 5 km offshore. The dominant periods of short-term thermal variability were 12, 17, and 24 h, reflecting both diurnal heat fluxes and inertial oscillations of Lake Ontario's thermocline. The thermocline in Lake Ontario was observed to oscillate by as much as 15 m, around a mean depth of 9 m, which is comparable to the mean depth of Toronto Harbour. Cold intrusions were found to quickly flow from the lake into the harbour and lead to rapid drops in temperature (e.g., as much as 15 °C in less than 4 h). Such “cold shock” events may be associated with a variety of negative effects on many aquatic organisms, especially warm-water fishes. We consider the potential impacts of the observed temperature variability on cool and warm-water fish species that are the target of restoration activities.

Novel architectures of polymer electrolyte membrane fuel cells: Efficiency enhancement and cost reduction

Three novel architectures of proton exchange membrane fuel cells (PEMFCs), called circular, square and octagonal duct-shaped architectures, are introduced and analyzed numerically. A three-dimensional computational fluid dynamics (CFD) code is used to solve the equations for a single domain of the cell under steady state and non-isothermal conditions. The numerical results are in reasonable agreement with the experimental data over a wide range of current density. The distributions of oxygen, hydrogen and water mass fraction, current density and temperature are studied for the three introduced configurations. The circular- and square-duct configurations show considerably better performance and offer several advantages over the conventional PEMFC configuration. These advantages are related to the way in which the reactant gases are supplied to the flow field, to the shorter channels used and to the lower cost of the PEMFC due to the less bipolar plates needed.Among the three configurations having the same active area and the same inlet area, the square-duct geometry shows considerably higher current density and more uniform water and temperature distributions. The square-duct configuration is, therefore, the best candidate to enhance the PEMFC efficiency while reducing its size and cost, and can be considered for the design of new generation of PEMFCs.

Numerical study of two-dimensional water vapor concentration and temperature distribution of combustion zones using tunable diode laser absorption tomography

The principle of gas temperature and concentration measurement based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) is introduced. Combining Computed Tomography (CT) with TDLAS, herein referred to as Tunable Diode Laser Absorption Tomography (TDLAT), reconstructs temperature and concentration distribution which are assumed as Gaussian function or paraboloid function. A pair of water absorption lines (7153.722cm−1 and 7153.748cm−1 and 7154.354cm−1) is selected to measure temperature by means of two-line technique. Radon transform is used to calculate projections of different path for reconstructing temperature distribution based on filtered backprojection algorithm. With a general normalization process, water vapor concentration distribution can be obtained simultaneously. The reconstruction results agree well with the original model. In consideration of laboratory verification and experimental condition, the TDLAT data consist of 13 projection angles and 11 parallel rays at each angle is discussed in this article, obtaining distribution map with a resolution of 20×20. Although the reconstruction value of the edge deviates a little from the original parameters, this method achieves relatively satisfactory outcome in general. The reconstruction error roughly increases with decreasing projection angles and parallel rays, additionally, the reconstruction accuracy is more dependent on the parallel ray number at each angle than the projection angle number. Appropriate grid partition is also important in reconstruction study, the optimal grid partition is 30×30 or near this magnitude when the system contains totally 18 projection angles and 27 parallel rays at each angle. This work proposes a feasible formula for reconstruction research with a small amount of projections and rays, theoretically, laying a foundation for experimental validation in the future.