Temperature Profile Data Research Articles

Improving the ocean and atmosphere in a coupled ocean–atmosphere model by assimilating satellite sea‐surface temperature and subsurface profile data

AbstractAn ensemble‐based data assimilation framework for a coupled ocean–atmosphere model is applied to investigate the influence of assimilating different types of ocean observations on the ocean and atmosphere simulation. The data assimilation is performed with the parallel data assimilation framework (PDAF) for the climate model AWI‐CM. Observations of the ocean, namely satellite sea‐surface temperature (SST) and temperature and salinity profiles, are assimilated into the ocean component. The atmospheric state is only influenced by the model dynamics. Different assimilation scenarios were carried out with different combinations of observations to investigate to what extent the assimilation into the coupled model leads to a better estimation of the state of the ocean as well as the atmosphere. The influence of the data assimilation is assessed by comparing the ocean prediction with dependent and independent ocean observations. For the atmosphere, the assimilation result is compared with the ERA‐Interim atmospheric reanalysis data. The ocean temperature and salinity are improved by all the assimilation scenarios in the coupled system. The assimilation leads to a response of the atmosphere throughout the troposphere and impacts the global atmospheric circulation. Globally the temperature and wind speed are improved in the atmosphere on average.

Satellite identification of atmospheric-surface-subsurface urban heat islands under clear sky

The urban heat island (UHI) is a major topic in the study of urban climates. However, comprehensive research on the atmospheric UHI (UHIAtm), surface UHI (UHISurf), and subsurface UHI (UHISub) simultaneously has yet not been reported. Using the MODIS land surface temperature and atmospheric profile data during the 2010–2016 period, we investigated the diurnal, seasonal, and vertical variations of UHIAtm, UHISurf, and UHISub in Beijing. The major findings include but are not limited to the following: As the altitude increases from 1000 hPa (near the surface) to 700 hPa (~3 km), the daytime UHIAtm intensity in summer decreases piecewise linearly with a rapid decline above 850 hPa (~1.5 km), while in spring and autumn it decreases after a slight increase in the lower atmosphere. The nighttime UHIAtm intensity decreases approximately linearly in all seasons with a rapid (gradual) decline in winter (summer). As the depth increases from the surface to ~0.2 m, the daytime intensity from UHISurf to UHISub decreases in summer but increases in the other seasons, while the nighttime trends are opposite to the daytime ones. The diurnal (seasonal) variation of UHISub intensity converges to the daily (annual) mean as the depth reaches ~0.5 m (10 m). These new findings have theoretical and practical implications for in-depth understanding of the urban thermal environment from the boundary layer to the subsurface.

Experimental study on integrated and autonomous conductivity-temperature-depth (CTD) sensor applied for underwater glider

This paper studies a novel CTD sensor (SZQ1-1) which is developed for underwater glider to meet the requirement of autonomous acquisition of high-quality profile hydrodynamic oceanography data. An independently developed electromagnetic induction type conductivity sensor, a quick response thermistor and a high-precision pressure sensor is used to integrate the CTD sensor. Several designs of compact mechanical structure and low-power control acquisition circuit are developed in the CTD sensor. The SZQ1-1 CTD is calibrated with measuring instrument in the laboratory and fourth-degree polynomial fitting equations are developed to fit the curves. After software-based calibration, the SZQ1-1 is compared with SBE 19plus by sea trial. The SZQ1-1 and SBE 19plus were carried by an underwater glider which dived in Northern South China Sea with a maximum depth of 500.36 m. Because the thermal lag error exists in the original data measured with the CTD sensor in the underwater glider, the measured conductivity and salinity data are revised again in the software. According to sea trial results, the real-time temperature, salinity and depth profile data obtained by SZQ1-1 sensor is consistent with the data measured with SBE 19plus.

Effects of CO2 Changes on Hyperspectral Infrared Radiances and Its Implications on Atmospheric Temperature Profile Retrieval and Data Assimilation in NWP

Although atmospheric CO2 is a trace gas, it has seasonal variations and has increased over the last decade. Its seasonal variation and increase have substantial radiative effects on hyperspectral infrared (IR) radiance calculations in both longwave (LW) and shortwave (SW) CO2 absorption spectral regions that are widely used for weather and climate applications. The effects depend on the spectral coverage and spectral resolution. The radiative effect caused by the increase of CO2 has been calculated to be greater than 0.5 K within 5 years, whereas a radiative effect of 0.1–0.5 K is introduced by the seasonal variation in some CO2 absorption spectral regions. It is important to take into account the increasing trend and seasonal variation of CO2 in retrieving the atmospheric temperature profile from hyperspectral IR radiances and in the radiance assimilation in numerical weather prediction (NWP) models. The simulation further indicates that it is very difficult to separate atmospheric temperature and CO2 information from hyperspectral IR sounder radiances because the atmospheric temperature signal is much stronger than that of CO2 in the CO2 absorption IR spectral regions.

On Generalized Fourier’s and Fick’s Laws in Bio-Convection Flow of Magnetized Burgers’ Nanofluid Utilizing Motile Microorganisms

This article describes the features of bio-convection and motile microorganisms in magnetized Burgers’ nanoliquid flows by stretchable sheet. Theory of Cattaneo–Christov mass and heat diffusions is also discussed. The Buongiorno phenomenon for nanoliquid motion in a Burgers’ fluid is employed in view of the Cattaneo–Christov relation. The control structure of governing partial differential equations (PDEs) is changed into appropriate ordinary differential equations (ODEs) by suitable transformations. To get numerical results of nonlinear systems, the bvp4c solver provided in the commercial software MATLAB is employed. Numerical and graphical data for velocity, temperature, nanoparticles concentration and microorganism profiles are obtained by considering various estimations of prominent physical parameters. Our computations depict that the temperature field has direct relation with the thermal Biot number and Burgers’ fluid parameter. Here, temperature field is enhanced for growing estimations of thermal Biot number and Burgers’ fluid parameter.

Numerical comparison of two operating modes of thermal energy storage tank for compression heat storage in adiabatic compressed air energy storage

• Thermal performance of multi-PCM energy storage tank is numerically analysed. • A thermodynamic comparison of two charging configurations is implemented. • A parametric study of PCM packing height is performed. • Results indicate that correct arrangement of PCM packing height is critical. • Preheating air after compression with part of excess electricity improves performance Two different charging modes of a thermal energy storage tank (TEST) system employing multi-phase change material for compression heat storage in an adiabatic compressed air energy storage process was simulated to compare their performance. The modes are mod1 with higher mass flow rate and low temperature and mod2 with higher temperature and low mass flow rate of heat transfer fluid respectively. A mathematical formulation of the energy interactions in the HTF and the PCM filling the TEST was discretized using implicit finite difference technique and solved in Matlab using a matrix inversion technique. The developed model showed good agreement with experimental data of temperature profile of heat transfer fluid during the charging mode. The two modes were compared using metrics such as charging rate, discharging rate, charging efficiency, discharging efficiency, charging and discharging exergy efficiency, and overall exergy and energy efficiency. It was found that mod2 performs better than mod1 in both the charging and discharging cycle. The round trip efficiency of mod1 ranges from 0.87 to 0.77 with a mean value of 0.76 whereas that for mod2 ranged from 0.97 to 0.79 with an average of 0.78. Moreover, the overall exergy efficiency ranges from a peak value of 0.48 and 0.55 to the least value of 0.33 and 0.44 in mod1 and mod2 respectively, corresponding to average efficiencies of 0.45 and 0.51 in mod1 and mod2 respectively. The numerical results show that using some part of the excess electricity of wind turbine to preheat air after compression is a promising solution to improve performance of A-CAES plants.

Obtenção numérica do perfil térmico durante passagem de fonte de calor nos materiais AISI 410, 304L e 430

O método de elementos finitos é uma análise numérica capaz de responder diversos problemas transientes, não lineares da engenharia. O objetivo desse trabalho foi realizar uma pesquisa experimental de análise numérica via elementos finitos, em busca da resposta a um aporte térmico em três materiais inoxidáveis, sendo eles AISI 410, AISI 304L e AISI 430. Para isso foi utilizado o software Ansys® Academic 2020R1, nele foram modeladas chapas nas dimensões de , com um caminho de passagem da fonte de calor de . Os materiais foram criados com suas propriedades físicas transiente. A fonte de calor adotada foi a Gaussiana, retirada de uma extensão matemática própria para o software. Foram consideradas as perdas de calor por condução na peça, convecção e radiação no ambiente. A construção do perfil de temperatura de cada material foi construída de acordo com a temperatura máxima atingida, temperatura em pontos específicos e máximo fluxo de temperatura. Os dados dos perfis de temperatura dos materiais foram comparados utilizando por análise estatística ANOVA, utilizando o teste de Tukey. Os resultados mostraram a possibilidade de realizar simulação de processos de soldagem com as condições de contorno adotadas, mostraram que não há uma diferença de máxima temperatura entre os três materiais, entretanto existe uma diferença significativa entre os máximos fluxos de temperatura obtidos entre os três matérias, fato justificado pelas suas diferenças de propriedades físicas. Além disso, os dados de perfil térmico permitem análises estruturais dos materiais, bem como predições de caminhos a seguir em ajuste de parâmetros experimentais.

Design, fabrication and validation of an improved coil for induction dilatometry

Dilatometry is a versatile tool to investigate thermal expansion or phase transformations in various materials based on the length changes upon heating and cooling. Since most modern thermal processes tend to take place at high heating and cooling rates it can be demonstrated that a large longitudinal temperature gradient within dilatometric samples impedes the accurate investigation of physical mechanisms. In this study we investigate how an instrumental advancement of the induction heating system can be implemented in a dilatometric setup in order to mitigate the temperature gradient and its effect on the measured length change for a wide range of heating rates. For this purpose a numerical method for heating design optimization using a FEM simulation of the dilatometric experiment is developed and validated. The presented heating component design method in combination with additive manufacturing capabilities allows for a more accurate and flexible method of detecting dilatation in a dilatometric setup. Extreme temperature differences of 140∘C for a maximum heating rate of 800∘C/s could be reduced by 15-45% within the sample using new optimized instrumentation. This leads to a more profound and exact interpretation of dilatometric data for high heating rates and complex time temperature profiles.

Estimating the Effective Soil Temperature at L-Band Using Multi-Temporal temperature Data

The effective soil temperature is an essential parameter in the process of the soil moisture retrieval by using the passive microwave remote sensing data. The modeled soil temperature profile data was widely adopted to calculate the soil effective temperature at L-band. Considering that the procedure of using land models to obtain soil temperature profile is cumbersome, this study mainly investigates the effectiveness of using thermal infrared soil surface temperature and air temperature as the input parameters to calculate the soil effective temperature at L-band. The results of this study show that the average value of multi-temporal thermal infrared surface temperature and the monthly mean of air temperature can accurately calculate the soil effective temperature with RMSE=0.57K based on the simulated data of 4 years.

Non-Linear Radiation, Chemical Reaction, and Soret/Dufour Effects on Magnetohydrodynamic Natural Convection About a Permeable Horizontal Circular Cylinder in Non-Darcy Porous Media With Heat Source/Sink

Abstract In this paper, the nonlinear radiation, chemical reaction, and Soret/Dufour effects on magnetohydrodynamic (MHD) natural convection about a permeable horizontal circular cylinder in non-Darcy porous media with heat source/sink are numerically analyzed. The surface of the horizontal circular cylinder is subjected to uniform wall temperature and uniform wall concentration (UWT/UWC). The governing equations are transformed into dimensionless, non-similar forms using suitable non-dimensional variables and then solved using Keller box method (KBM). Comparisons with previously published work are performed, and the results are found to be in an excellent agreement. Numerical data of the dimensionless temperature profile, the dimensionless concentration profile, the Nusselt number, and the Sherwood number are presented in graphic and tabular forms for the main parameters. The physical aspects of the problem are discussed in detail. The Nusselt number increases with increasing the Soret parameter, radiation parameter, and surface temperature ratio. Increasing the Dufour parameter, radiation parameter, surface temperature ratio, coefficient of space-dependent internal heat generation/absorption, and dimensionless chemical reaction parameter enhances the Sherwood number.

Analytical and numerical solutions of heat and mass transfer of boundary layer flow in the presence of a transverse magnetic field

AbstractThe present investigation aims to study the effect of a transverse magnetic field with the presence of an adverse pressure gradient on the two‐dimensional laminar incompressible boundary layer flow over a flat plate. Using appropriated similarity transformations, the partial differential equations governing the studied problems are transformed into the ordinary nonlinear differential equations. Thereafter, these equations are solved numerically and analytically using the fourth‐order Runge‐Kutta method featuring shooting technique and the Adomian decomposition method, respectively. Obtained results reveal an excellent agreement between analytical and numerical data for temperature and concentration profiles.

Focus shift control of a novel 30 kW laser remote scanner for large-scale industrial sheet and plate metal applications

To overcome current limitations in laser remote processing of large-scale sheet and plate metal applications, an automated laser remote scanner (LRS) with a 30 kW laser power has been developed. Due to the high laser power, an unacceptable focus shift occurs at the processing location, mainly generated by the fused silica optics. A computationally efficient real-time focus shift compensation and control of the focus position have been investigated and are presented. In the first section, the 30 kW LRS concept is briefly introduced. Section two explains the focus shift effect and presents its impact on manufacturing scenarios in welding and cutting. The third section highlights significant effects accounted for: thermo-optical, stress-optical, geometric, and ambient. A set of simulated data of temperature, refractive index, and focus shift profiles have been generated in section four and model the performance of the 30 kW LRS. The results are discussed and a summary is given.

ZERO NANOPARTICLES FLUX EFFECT ON NATURAL CONVECTION ABOUT A CYLINDER OF ELLIPTIC CROSS SECTION IN POROUS MEDIA FILLED WITH A NANOFLUID

In this investigation, numerical analysis was performed on the zero nanoparticle flux (ZNF) effect on natural convection in a cylinder with an elliptical cross section embedded in Darcy porous media filled with a nanofluid. The boundary conditions of the cylinder with the elliptical cross section were maintained at uniform wall temperature and ZNF to ensure that the results obtained were realistic and useful. The model adopted for the nanofluid incorporated the effects of Brownian motion and thermophoresis. The non-similar governing equations were obtained by using an appropriate coordinate transformation, and then solved by the Keller box method. Comparisons with previously published work showed good agreement. Numerical data for the dimensionless temperature profiles and Nusselt numbers are presented in graphical and tabular forms for the eccentric angle (B), buoyancy ratio (Nr = 0.4), Brownian motion parameter (Nb = 0.3), thermophoresis parameter (Nt), and the Lewis number (Le). Increasing the thermophoresis parameter and the Lewis number decreased the Nusselt number. For blunt orientation, the Nusselt number first increased with increasing eccentric angle, reached a maximum, and then decreased to zero. For slender orientation, the Nusselt number decreased monotonically. The Nusselt number in the blunt configuration initially increased with an increase in the aspect ratio, attained a maximum, and then gradually decreased. For the slender configuration, the Nusselt number decreased. In this paper, the results of the investigated physical aspects of the problem are discussed in detail.

Hydrography of the Eastern Mediterranean basin derived from argo floats profile data

As the Eastern Mediterranean integrates different sub-basins with important hydrological features, during recent decades it has often become a target of study by the oceanographic community. The recent expansion of observational tools and methods in the marginal seas has allowed more enhanced studies of the oceanographic processes that dominate such areas. In this work, temperature and salinity profile data collected by Argo floats in the Eastern Mediterranean are analysed for the period 2004–2017. The spatio-temporal variability of the basin's physical properties, together with the depicted changes in the different sub-basins, is investigated in an attempt to construct the latest hydrographic picture of the region. The findings describe the dominant water masses and reveal a general positive trend in the basin's thermohaline properties. The inter-annual variability of the stored heat and salt, and their distribution in the water column, reveals strong climatic signals that are dominated by previously reported alternations of the general circulation and convection events in the area. The latter are correlated with the surface temperature and salinity fields and are traced within the area's different sub-basins. In the early period (2004–2010), data from Levantine and Ionian depict inter-annual variability of the upper layers salinity field that is correlated with previously reported alternations of the Levantine's circulation, and intermediate water production in the Ionian. During the latest period (2012–2017), when the data coverage is denser and more representative for the wider area of the Eastern Mediterranean, the Adriatic sub-basin presents intense dense water production activity while the Aegean Sea undergoes a relaxation period with significant variability at intermediate layers due to water mass exchanges.

Towards quantifying uncertainty in ocean heat content changes using synthetic profiles

Observational estimates of global ocean heat content (OHC) change are used to assess Earth’s energy imbalance over the 20th Century. However, intercomparison studies show that the mapping methods used to interpolate sparse ocean temperature profile data are a key source of uncertainty. We present a new approach to assessing OHC mapping methods using ‘synthetic profiles’ generated from a state-of-the-art global climate model simulation. Synthetic profiles have the same sampling characteristics as the historical ocean temperature profile data but are based on model simulation data. Mapping methods ingest these data in the same way as they would real observations, but the resultant mapped fields can be compared to a model simulation ‘truth’. We use this approach to assess two mapping methods that are used routinely for climate monitoring and initialisation of decadal forecasts. The introduction of the Argo network of autonomous profiling floats during the 2000s drives clear improvements in the ability of these methods to reconstruct the variability and spatial structure of OHC changes. At depths below 2000 m, both methods underestimate the magnitude of the simulated ocean warming signal. Temporal variability and trends in OHC are better captured in the better-observed northern hemisphere than in the southern hemisphere. At all depths, the sampling characteristics of the historical data introduces some spurious variability in the estimates of global OHC on sub-annual to multi-annual timescales. However, many of the large scale spatial anomalies, especially in the upper ocean, are successfully reconstructed even with sparse observations from the 1960s, demonstrating the potential to construct historical ocean analyses for assessing decadal predictions. The value of using accurate global covariances for data-poor periods is clearly seen. The results of this ‘proof-of-concept’ study are encouraging for gaining further insights into the capabilities and limitations of different mapping methods and for quantifying uncertainty in global OHC estimates.

More Than 50 Years of Successful Continuous Temperature Section Measurements by the Global Expendable Bathythermograph Network, Its Integrability, Societal Benefits, and Future

The first eXpendable BathyThermographs (XBTs) were deployed in the 1960s in the North Atlantic Ocean. In 1967 XBTs were deployed in operational mode to provide a continuous record of temperature profile data along repeated transects, now known as the Global XBT Network. The current network is designed to monitor ocean circulation and boundary current variability, basin-wide and trans-basin ocean heat transport, and global and regional heat content. The ability of the XBT Network to systematically map the upper ocean thermal field in multiple basins with repeated trans-basin sections at eddy-resolving scales remains unmatched today and cannot be reproduced at present by any other observing platform. Some repeated XBT transects have now been continuously occupied for more than 30 years, providing an unprecedented long-term climate record of temperature and geostrophic velocity profiles that are used to understand variability in ocean heat content, sea level change, and meridional ocean heat transport. Here, we present key scientific advances in understanding the changing ocean and climate system supported by XBT observations. Improvement in XBT data quality and its impact on computations, particularly of ocean heat content, are presented. Technology development for probes, launchers, and transmission techniques are also discussed. Finally, we offer new perspectives for the future of the Global XBT Network.

Optimal sizing of an AC‐coupled hybrid power system considering incentive‐based demand response

This study investigates the impact of incentive-based demand response on the optimal economic sizing of hybrid power systems for a remote area in South Australia. The hybrid power systems are modelled as AC-coupled system with various power generation and energy storage systems including diesel generators, solar photovoltaics, wind turbines, battery storages and flywheels. Operating reserve requirements are introduced to ensure a specified reliability with variable renewable energy generation and consumer loads. Incentive-based demand response is introduced to allow a reduction in customer loads, up to a maximum value, during peak load events. Customers receive a financial benefit as an incentive for the total demand response energy reduction. Active power operation of four different power system configurations is modelled over one year in hourly time steps. The study uses real data for customer demand, wind speed, solar insolation and ambient temperature profiles in a specific location. The hybrid power systems with demand response are optimised to minimise the system net present cost in project lifetime (20 years) using a particle swarm optimisation algorithm. Sensitivity analysis of levellised cost of energy for various values of the maximum demand response power and the incentive payments are also carried out.

Robust Regression for Automatic Fusion Plasma Analysis Based on Generative Modeling

The first step to realize automatic experimental data analysis for fusion plasma experiments is fitting noisy data of temperature and density spatial profiles, which are obtained routinely. However, it has been difficult to construct algorithms that fit all the data without over- and under-fitting. In this paper, we show that this difficulty originates from the lack of knowledge of the probability distribution that the measurement data follow. We demonstrate the use of a machine learning technique to estimate the data distribution and to construct an optimal generative model. We show that the fitting algorithm based on the generative modeling outperforms classical heuristic methods in terms of the stability as well as the accuracy.

Definition of the profile gain factor and its application for internal transport barrier analysis in torus plasmas

In this paper, a new criterion for the internal transport barrier (ITB) formation is proposed by defining a unique scalar parameter, the profile gain factor. The profile gain factor shows degree of the confinement improvement with respect to an arbitrary reference temperature profile in the L-mode. As the reference L-mode profile for the large helical device (LHD), the edge ion temperature profile data is extrapolated to the core by the L-mode profile function, which is characterized by the thermal diffusion coefficient being proportional to the local ion temperature. The profile gain factor is defined as the ratio of the ion stored energy experimentally measured to that evaluated from the reference L-mode profile. The proposed method is applied to the LHD experimental data, and its capability for quantification of the ITB strength is demonstrated.

Sensitivity study of hardness profile of 4340 steel disc hardened by induction according to machine parameters and geometrical factors

An adequate induction heat treatment operation should always identify, previously, the probable temperature distribution and hardness profile behavior in specific regions of the treated component according to heating process parameters. This paper presents an analysis of the effects of some geometrical factor related to the component and the coil and machine parameters on temperature distribution and case depth of an AISI 4340 low-alloy steel disc heated by induction. A Comsol model was created, defined as a group of process parameters followed by a mesh study. A Matlab algorithm coupled to the simulation model was designed to handle a large number of simulations and export temperature profile data. The case depth is then interpolated from collected temperature data and a statistical analysis was developed to create the hardness prediction model. The experimental tests conducted under the same process parameters support the numerical model results and approve the simulation, the prediction modeling, and the statistical study.