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1
Qiao, Fangli, Yeli Yuan, Jia Deng, Dejun Dai e Zhenya Song. "Wave–turbulence interaction-induced vertical mixing and its effects in ocean and climate models". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, n. 2065 (13 aprile 2016): 20150201. http://dx.doi.org/10.1098/rsta.2015.0201.
Testo completoAbstract (sommario):
Heated from above, the oceans are stably stratified. Therefore, the performance of general ocean circulation models and climate studies through coupled atmosphere–ocean models depends critically on vertical mixing of energy and momentum in the water column. Many of the traditional general circulation models are based on total kinetic energy (TKE), in which the roles of waves are averaged out. Although theoretical calculations suggest that waves could greatly enhance coexisting turbulence, no field measurements on turbulence have ever validated this mechanism directly. To address this problem, a specially designed field experiment has been conducted. The experimental results indicate that the wave–turbulence interaction-induced enhancement of the background turbulence is indeed the predominant mechanism for turbulence generation and enhancement. Based on this understanding, we propose a new parametrization for vertical mixing as an additive part to the traditional TKE approach. This new result reconfirmed the past theoretical model that had been tested and validated in numerical model experiments and field observations. It firmly establishes the critical role of wave–turbulence interaction effects in both general ocean circulation models and atmosphere–ocean coupled models, which could greatly improve the understanding of the sea surface temperature and water column properties distributions, and hence model-based climate forecasting capability.
2
Ostroukh, Andrey, Andrey Mavrin e Nataliya Surkova. "Technological Processes Automation of Chemical Heat Treatment at Industrial Enterprises". Advanced Materials Research 1098 (aprile 2015): 120–25. http://dx.doi.org/10.4028/www.scientific.net/amr.1098.120.
Testo completoAbstract (sommario):
This paper presents analysis of chemical and thermal processing (CTP) methods to support multi-component gas atmosphere processes and their mathematical models as objects in the automated process control system (APCS). CTP mathematical models, algorithms, interaction structures and concepts of APCS components based on a specialized electronic controller have been proposed and implemented. The system provides a time control of all the necessary gas atmosphere parameters – its composition, temperature, pressure, with the possibility of using saturating medium of up to four components. Implementation of the system will improve the service properties of processed products, reduce the rate of spoilage and the psychophysical stress of the production staff, as well as reduce the overall CTP time.
3
Mehra, Vinayak, Varun Gupta e Pradeep Khanna. "MATHEMATICAL MODELLING TO PREDICT ANGULAR DISTORTION IN MIG WELDING OF STAINLESS STEEL 202 PLATES". Journal of Production Engineering 23, n. 2 (30 dicembre 2020): 16–20. http://dx.doi.org/10.24867/jpe-2020-02-016.
Testo completoAbstract (sommario):
In present research, mathematical models have been established to predict the angular distortion in Metal Inert Gas(MIG) welding for 6mm plates of SS 202 grade for butt welded joints. The filler metal used was a continuously fed solid metal wire of stainless steel (304L).100% Argon gas was used to serve the purpose of shielding the weld pool from the atmosphere as it does not dissociate at high temperatures. This prevented any turbulence in the welding arc and deterioration in weld quality. To obtain experimental samples, the design matrix was developed using the statistical technique of central composite rotatable design (CCRD). Analysis of Variance (ANOVA) technique was used for the adequacy check of the models developed. The models developed can be used to find direct and interaction effect of the input parameters, namely welding speed (WS), voltage (V), nozzle to plate distance (NPD), torch angle (Ɵ) and wire feed rate (WFR) on the angular distortion.
4
Li, Ke Hua, Jin Yong Yu e Jun Wei Lei. "Research on Modeling and Simulation of Sonar Performance Using Simulink". Applied Mechanics and Materials 138-139 (novembre 2011): 804–9. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.804.
Testo completoAbstract (sommario):
With respect to different weather and sea conditions, the acoustic model under ocean environment was proposed by analyzing the interaction characteristics between sonar and environment. Based on the sonar equation, the performance mathematical models of active and passive sonar were produced with considering acoustic characteristics of the target and parameters of the marine environment. Simulation results of target detection performance for different target types, sonar parameters and sea conditions show the validity of the proposed model.
5
TURCANU, Alexandru, e Leonard-Călin-Valentin DOBRE. "DIMENSIONAREA SISTEMULUI DE PROPULSIE AL UNUI VEHICUL ELECTRIC. STUDIU DE CAZ". "ACTUALITĂŢI ŞI PERSPECTIVE ÎN DOMENIUL MAŞINILOR ELECTRICE (ELECTRIC MACHINES, MATERIALS AND DRIVES - PRESENT AND TRENDS)" 2020, n. 1 (10 febbraio 2021): 1–14. http://dx.doi.org/10.36801/apme.2020.1.4.
Testo completoAbstract (sommario):
This paper aims to present to readers concrete mathematical models, transposed into simulation schemes, to calculate the forces acting on a car at its interaction with the road and the atmosphere, to properly size the electric motor and batteries of an electric car. For the calculation of these forces, a table with predefined values such as vehicle mass, rolling resistance coefficient, gear ratio, wheel radius, was used throughout the work. In the second section of the paper, the values of the resistance forces that oppose the movement of the vehicle and the traction force necessary to overcome these resistive forces were determined. The mathematical calculation model was compiled in Matlab and the graphs in figures 3-9 were obtained.
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Heywood, Karen J., Sunke Schmidtko, Céline Heuzé, Jan Kaiser, Timothy D. Jickells, Bastien Y. Queste, David P. Stevens et al. "Ocean processes at the Antarctic continental slope". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, n. 2019 (13 luglio 2014): 20130047. http://dx.doi.org/10.1098/rsta.2013.0047.
Testo completoAbstract (sommario):
The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean–atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An iron-cycling model embedded in an eddy-permitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multi-disciplinary Southern Ocean observing system.
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Mukhartova, Iuliia, Alexander Krupenko, Polina Mangura e Alexander Olchev. "Mathematical Modeling of Vegetation Heterogeneity and Complex Topography Effects on Turbulent Exchange of GHG within the Atmospheric Surface Layer". Proceedings 2, n. 20 (17 ottobre 2018): 1310. http://dx.doi.org/10.3390/proceedings2201310.
Testo completoAbstract (sommario):
The local-scale 2D and 3D models of greenhouse gases (GHG) exchange between a non-uniform land surface and the atmosphere were developed. They are based on solution of the system of averaged Navier-Stokes, continuity and diffusion-advection equations. For numerical solution of the differential equations the stable finite-difference schemes were suggested. The models were applied to derive effects of complex topography and vegetation heterogeneity on 2D-3D air flow patterns, as well as on CO2 exchange within the atmospheric surface layer. Several numerical experiments were also provided to describe the air-flow re-establishing after its interaction with some obstacle (e.g., forest edge). Quantitative criteria for selection of the experimental sites for continuous eddy covariance flux measurements characterized by minimum effects of horizontal advection on measured fluxes were suggested.
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Kovalnogov, Vladislav N., Yuriy A. Khakhalev, Ekaterina V. Tsvetova e Larisa V. Khakhaleva. "MATHEMATICAL MODELING AND NUMERICAL STUDY OF ATMOSPHERIC BOUNDARY LAYER NEAR WINDFARMS". Автоматизация процессов управления 3, n. 65 (2021): 33–40. http://dx.doi.org/10.35752/1991-2927-2021-3-65-33-40.
Testo completoAbstract (sommario):
The article analyzes Russian and foreign sources relating to the interaction of wind turbines with the surface layers of the atmosphere. It specifies the main problems of mathematical modeling of the atmospheric boundary layer near the wind farms due to adverse meteorological conditions, in particular, constant zero crossings in the autumn-winter period, various precipitation, a wide time range, air parameters, terrain and other features. The authors analyze the evolution of mathematical models of turbulence to describe the boundary layer near wind turbines from earlier to rapidly developing and currently used. To achieve greater accuracy and naturalism, it is proposed to use high-performance efficient algorithms based on combining scales and physics of phenomena. The authors propose a mathematical model for studying the state of the atmospheric polydisperse boundary layer under conditions of the Ulyanovsk wind farm, taking into account the dispersed particles in the flow, surface curvature, pressure gradient and other influences.
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Sangale, Bhagwan, U. M. Khodke H. W. Awari e Vishal Ingle. "Crop Growth Simulation Modelling - A Review". International Journal of Current Microbiology and Applied Sciences 11, n. 1 (10 gennaio 2022): 78–84. http://dx.doi.org/10.20546/ijcmas.2022.1101.010.
Testo completoAbstract (sommario):
Agriculture plays a key role in overall economic and social wellbeing of the specially developing countries. Now it is the right option to increase the quality and quantity of food production through the technological and managerial interventions like crop growth and yield prediction models. Agricultural models are mathematical equations that represent the reactions that occur within the plant and the interactions between the plant and its environment. The model simulates or imitates the behaviour of real crop by predicting the growth of its components, such as leaves, roots, stems and grains. Thus, a crop growth model not only predicts the final state of total biomass or harvestable yield, but also contains quantitative information about major processes involved in the growth and development of a plant. Crop Growth Simulation models are a formal way to present quantitative knowledge about how a crop grows in interaction with its environment. Using weather data and other data about the crop environment, these models can simulate crop development, growth, yield, water, and nutrient uptake. Crop models are mathematical algorithms that capture the quantitative information of agronomy and physiology experiments in a way that can explain and predict crop growth and development. They can simulate many seasons, locations, treatments, and scenarios in a few minutes. Crop models contribute to agriculture in many ways. They help explore the dynamics between the atmosphere, the crop, and the soil, assist in crop agronomy, pest management, breeding, and natural resource management, and assess the impact of climate change.
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Gusev, E. M., e O. N. Nasonova. "Simulating of snow cover formation by the model of interaction between the land surface and the atmosphere (SWAP)". Ice and Snow 59, n. 2 (11 giugno 2019): 167–81. http://dx.doi.org/10.15356/2076-6734-2019-2-401.
Testo completoAbstract (sommario):
In framework of the project «The Earth system Models – Snow Models Intercomparison Project» (ESMSnowMIP), calculations of snow storages were carried out on ten experimental sites organized for longterm monitoring of the snow cover variability in various regions of the globe. The calculation method is based on the physical and mathematical description of heat and moisture exchange processes occurring within the system «ground water – soil – vegetation cover/snow cover – surface layer of the atmosphere», and it is implemented in the form of the model of interaction between the land surface and the atmosphere (SWAP). The model was developed at the Institute of water problems (IWP) of Russian Academy of Sciences. The model makes possible to calculate components of water and heat balances and different characteristics of the hydrological regime of terrestrial ecosystems and river basins having different spatial scales and located in different natural conditions. Good quality of reproduction of the snow storages variability on all considered sites is reached that allows consideration of the SWAP model as one of the best models of the snow cover formation. Thus, the SWAP model has a sufficiently optimal degree of complexity of the algorithm for reproducing the dynamics of snow cover, which is necessary and sufficient in global and regional hydrological models describing formation of the water balance of the land in the cold regions of the planet, and can be used to create scenario forecasts of snow dynamics (as the important part of the cryosphere). This conclusion is verified by the results of using the SWAP model to reproduce long-term variability of snow storages in basins of the River Lena and the River Ob (with its tributary Irtysh) which are the two largest rivers of the Russian Federation. The calculated and measured characteristics of snow cover dynamics for these basins are shown to be in good agreement.
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Popov, O., A. Iatsyshyn, V. Kovach, V. Artemchuk, D. Taraduda, V. Sobyna, D. Sokolov et al. "Physical Features of Pollutants Spread in the Air During the Emergency at NPPs". Nuclear and Radiation Safety, n. 4(84) (19 dicembre 2019): 88–98. http://dx.doi.org/10.32918/nrs.2019.4(84).11.
Testo completoAbstract (sommario):
The authors carried out a thorough study of the features of the spread of hazardous chemicals in the surface layer of the atmosphere in the event of an emergency at the site of a nuclear power plant. In order to ensure the continuous operation of the stations in their territories, various ancillary technogenic facilities are located and operate, which release emissions of non-radiation pollutants into the atmosphere. Under various negative circumstances of a technical and natural nature, emergencies may occur due to significant chemical pollution of the atmospheric air in and outside the sanitary protection zone. The prevention of such emergencies is based on environmental monitoring in the locations of man-made objects and their preventive forecast. Implementation of these measures is not possible without the use of effective methods based on mathematical models of environmental pollution by anthropogenic objects, and the hardware and software that implement these methods. The main stages of the development of information and technical methods of prevention of such emergencies are given and described. Different scenarios of emergencies are described as a result of the release of chemicals into the atmosphere at these sites. A conceptual scheme for the distribution of impurities in the atmosphere due to man-made emissions has been developed. The peculiarities of atmospheric air propagation under stationary and non-stationary emission conditions are described in detail. It is established that the most determinants of influence on the concentration distribution of impurities are: mode and conditions of emission, type of source, direction, and velocity of the wind, state of the atmosphere, chemical interaction with other substances in the atmospheric air, gravitational deposition, leaching of sediments, absorption of the underlying surface. surface, terrain. The results obtained will be used in the process of developing mathematical models for the propagation of pollutants in the atmospheric air from the emissions of nuclear power plants during relevant emergencies.
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LINTON, C. M. "Towards a three-dimensional model of wave–ice interaction in the marginal ice zone". Journal of Fluid Mechanics 662 (15 ottobre 2010): 1–4. http://dx.doi.org/10.1017/s0022112010004258.
Testo completoAbstract (sommario):
Over the past forty or so years, considerable advances have been made in our understanding of the effects of ocean waves on sea ice, and vice versa, with observations, experiments and theory all playing their part. Recent years have seen the development of ever more sophisticated mathematical models designed to represent the physics more accurately and incorporate new features. What is lacking is an approach to three-dimensional scattering for ice floes that is both accurate and efficient enough to be used as a component in a theory designed to model the passage of directional wave spectra through the marginal ice zone. Bennetts & Williams (J. Fluid Mech., 2010, this issue, vol. 662, pp. 5–35) have brought together a number of solution techniques honed on simpler problems to provide just such a component.
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Qi, Di, e Andrew J. Majda. "Low-Dimensional Reduced-Order Models for Statistical Response and Uncertainty Quantification: Two-Layer Baroclinic Turbulence". Journal of the Atmospheric Sciences 73, n. 12 (9 novembre 2016): 4609–39. http://dx.doi.org/10.1175/jas-d-16-0192.1.
Testo completoAbstract (sommario):
Abstract Accurate uncertainty quantification for the mean and variance about forced responses to general external perturbations in the climate system is an important subject in understanding Earth’s atmosphere and ocean in climate change science. A low-dimensional reduced-order method is developed for uncertainty quantification and capturing the statistical sensitivity in the principal model directions with largest variability and in various regimes in two-layer quasigeostrophic turbulence. Typical dynamical regimes tested here include the homogeneous flow in the high latitudes and the anisotropic meandering jets in the low latitudes and/or midlatitudes. The idea in the reduced-order method is from a self-consistent mathematical framework for general systems with quadratic nonlinearity, where crucial high-order statistics are approximated by a systematic model calibration procedure. Model efficiency is improved through additional damping and noise corrections to replace the expensive energy-conserving nonlinear interactions. Model errors due to the imperfect nonlinear approximation are corrected by tuning the model parameters using linear response theory with an information metric in a training phase before prediction. Here a statistical energy principle is adopted to introduce a global scaling factor in characterizing the higher-order moments in a consistent way to improve model sensitivity. The reduced-order model displays uniformly high prediction skill for the mean and variance response to general forcing for both homogeneous flow and anisotropic zonal jets in the first 102 dominant low-wavenumber modes, where only about 0.15% of the total spectral modes are resolved, compared with the full model resolution of 2562 horizontal modes.
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Rombouts, J., e M. Ghil. "Oscillations in a simple climate–vegetation model". Nonlinear Processes in Geophysics 22, n. 3 (7 maggio 2015): 275–88. http://dx.doi.org/10.5194/npg-22-275-2015.
Testo completoAbstract (sommario):
Abstract. We formulate and analyze a simple dynamical systems model for climate–vegetation interaction. The planet we consider consists of a large ocean and a land surface on which vegetation can grow. The temperature affects vegetation growth on land and the amount of sea ice on the ocean. Conversely, vegetation and sea ice change the albedo of the planet, which in turn changes its energy balance and hence the temperature evolution. Our highly idealized, conceptual model is governed by two nonlinear, coupled ordinary differential equations, one for global temperature, the other for vegetation cover. The model exhibits either bistability between a vegetated and a desert state or oscillatory behavior. The oscillations arise through a Hopf bifurcation off the vegetated state, when the death rate of vegetation is low enough. These oscillations are anharmonic and exhibit a sawtooth shape that is characteristic of relaxation oscillations, as well as suggestive of the sharp deglaciations of the Quaternary. Our model's behavior can be compared, on the one hand, with the bistability of even simpler, Daisyworld-style climate–vegetation models. On the other hand, it can be integrated into the hierarchy of models trying to simulate and explain oscillatory behavior in the climate system. Rigorous mathematical results are obtained that link the nature of the feedbacks with the nature and the stability of the solutions. The relevance of model results to climate variability on various timescales is discussed.
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Rombouts, J., e M. Ghil. "Oscillations in a simple climate–vegetation model". Nonlinear Processes in Geophysics Discussions 2, n. 1 (2 febbraio 2015): 145–78. http://dx.doi.org/10.5194/npgd-2-145-2015.
Testo completoAbstract (sommario):
Abstract. We formulate and analyze a simple dynamical systems model for climate–vegetation interaction. The planet we consider consists of a large ocean and a land surface on which vegetation can grow. The temperature affects vegetation growth on land and the amount of sea ice on the ocean. Conversely, vegetation and sea ice change the albedo of the planet, which in turn changes its energy balance and hence the temperature evolution. Our highly idealized, conceptual model is governed by two nonlinear, coupled ordinary differential equations, one for global temperature, the other for vegetation cover. The model exhibits either bistability between a vegetated and a desert state or oscillatory behavior. The oscillations arise through a Hopf bifurcation off the vegetated state, when the death rate of vegetation is low enough. These oscillations are anharmonic and exhibit a sawtooth shape that is characteristic of relaxation oscillations, as well as suggestive of the sharp deglaciations of the Quaternary. Our model's behavior can be compared, on the one hand, with the bistability of even simpler, Daisyworld-style climate–vegetation models. On the other hand, it can be integrated into the hierarchy of models trying to simulate and explain oscillatory behavior in the climate system. Rigorous mathematical results are obtained that link the nature of the feedbacks with the nature and the stability of the solutions. The relevance of model results to climate variability on various time scales is discussed.
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Rozhdestvensky, Kirill. "Study of Underwater and Wave Gliders on the Basis of Simplified Mathematical Models". Applied Sciences 12, n. 7 (29 marzo 2022): 3465. http://dx.doi.org/10.3390/app12073465.
Testo completoAbstract (sommario):
Both underwater and wave gliders are known as autonomous unmanned energy-saving vehicles which have recently found applications for monitoring the world ocean. The paper under consideration discusses simplified mathematical models of these platforms enabling the straightforward parametric investigation into relationships between their parameters and performance. In its first part the paper discusses equations describing the motion of an underwater glider (UG) in a vertical plane as a basis for derivations relating geometric, kinematic and hydrodynamic characteristics of UG and its lifting system with relative differential buoyancy and pitch angle. Obtained therewith are formulae for the estimation of the UG glide path speed, lift-to-drag ratio, range of navigation and endurance. The approach is exemplified for typical cases of the UG conceived as winged bodies of revolution and flying wings. The calculated results feature dependencies of the UG speed on its configuration and volume as well as on the angle of attack for different magnitudes of relative buoyancy. Also considered is an optimal mode of operation, based on the maximization of the lift-to-drag ratio. The second part of the paper is dedicated to the estimation of the thrust and speed of a wave glider (WG), comprising a surface module (float) and underwater module represented by a wing, with the use of a simplified mathematical modeling intended to clarify the influence of the parameters upon the performance of the WG. The derivations led to an equation of forced oscillations of the vehicle accounting for the interaction of the upper and lower modules, connected by a rigid umbilical. The exciting impact of progressive waves of a given length and amplitude is found through the calculation of the variation of a buoyancy force in accordance with the Froude–Krylov hypothesis. The derivatives of time-varying lift with respect to kinematic parameters, entering the equation of vertical motion of the WG, as well as coefficients of instantaneous and time-averaged thrust force, are found by resorting to the oscillating hydrofoil theory. The derivation of the available thrust and the approximate calculation of the drag of the vehicle with account of wave and viscous components enable the evaluation of the speed of the WG for the prescribed geometry of the craft and wave motion parameters.
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Yao, Tandong, Fuyuan Wu, Lin Ding, Jimin Sun, Liping Zhu, Shilong Piao, Tao Deng, Xijun Ni, Hongbo Zheng e Hua Ouyang. "Multispherical interactions and their effects on the Tibetan Plateau's earth system: a review of the recent researches". National Science Review 2, n. 4 (1 dicembre 2015): 468–88. http://dx.doi.org/10.1093/nsr/nwv070.
Testo completoAbstract (sommario):
Abstract The Tibetan Plateau (TP) is a regional Earth system showing very strong interactions among its lithosphere, hydrosphere, cryosphere, biosphere, atmosphere, and anthrosphere. These interactions manifest TP's impact on surrounding regions and reflect TP's response to the global change. Quantifying the multispherical interactions is critically important to understand the TP environment. Our recent years researches including the ongoing program entitled ‘Tibetan Multi-Spheres Interactions and Their Resource-Environment Significance (TIMI)’, the completed program entitled. ‘Paleo-Altitudes of Tibetan Plateau and Environment (PATE)’, as well as the other relating projects have focused on multidisciplinary research approaches and emphasized on three major pathways: Eurasia-Indian plates collision on deep-Earth dynamics, uplift impact on Earth's mantle–crust dynamics, and contemporary interface on land surface and atmospheric dynamics. Our researches have taken in situ measurement as priority and developed several platforms of data acquisition and analysis, including the platforms of water-phase transformations, and ecosystem observations. Our field investigations have been conducted to obtain data about stratum, paleontology, paleoenvironment, genetic differentiation of animals and plants. We have developed conceptual and mathematical models for crust uplift formation, paleoclimate, glacial melt, water–air interface flux, vegetation climate, and soil erosion. We have also assessed the anthropogenic impacts on environment. Our researches have achieved new and reliable redating of the mantle–crust interaction and initial formation of the TP, found the interaction between tectonics and uplift of the TP and resultant paleoaltitude acting as a spreading source; discovered the interaction between the westerlies and Indian monsoon acting as a control chain that dominates the TP's contemporary environment. The scientific results can play fundamental roles in supporting the TP's resource exploration and societal sustainable development.
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Kumar, Sachin, e Brij Mohan. "A study of multi-soliton solutions, breather, lumps, and their interactions for kadomtsev-petviashvili equation with variable time coeffcient using hirota method". Physica Scripta 96, n. 12 (24 novembre 2021): 125255. http://dx.doi.org/10.1088/1402-4896/ac3879.
Testo completoAbstract (sommario):
Abstract This paper investigates the new KP equation with variable coefficients of time ‘t’, broadly used to elucidate shallow water waves that arise in plasma physics, marine engineering, ocean physics, nonlinear sciences, and fluid dynamics. In 2020, Wazwaz [1] proposed two extensive KP equations with time-variable coefficients to obtain several soliton solutions and used Painlevé test to verify their integrability. In light of the research described above, we chose one of the integrated KP equations with time-variable coefficients to obtain multiple solitons, rogue waves, breather waves, lumps, and their interaction solutions relating to the suitable choice of time-dependent coefficients. For this KP equation, the multiple solitons and rogue waves up to fourth-order solutions, breather waves, and lump waves along with their interactions are achieved by employing Hirota's method. By taking advantage of Wolfram Mathematica, the time-dependent variable coefficient's effect on the newly established solutions can be observed through the three-dimensional wave profiles, corresponding contour plots. Some newly formed mathematical results and evolutionary dynamical behaviors of wave-wave interactions are shown in this work. The obtained results are often more advantageous for the analysis of shallow water waves in marine engineering, fluid dynamics, and dusty plasma, nonlinear sciences, and this approach has opened up a new way to explain the dynamical structures and properties of complex physical models. This study examines to be applicable in its influence on a wide-ranging class of nonlinear KP equations.
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Mohsin, Muhammad, Qiang Zhu, Sobia Naseem, Muddassar Sarfraz e Larisa Ivascu. "Mining Industry Impact on Environmental Sustainability, Economic Growth, Social Interaction, and Public Health: An Application of Semi-Quantitative Mathematical Approach". Processes 9, n. 6 (30 maggio 2021): 972. http://dx.doi.org/10.3390/pr9060972.
Testo completoAbstract (sommario):
The mining industry plays a significant role in economic growth and development. Coal is a viable renewable energy source with 185.175 billion deposits in Thar, which has not been deeply explored. Although coal is an energy source and contributes to economic development, it puts pressure on environmental sustainability. The current study investigates Sindh Engro coal mining’s impact on environmental sustainability and human needs and interest. The Folchi and Phillips Environmental Sustainability Mathematics models are employed to measure environmental sustainability. The research findings demonstrated that Sindh Engro coal mining is potentially unsustainable for the environment. The toxic gases (methane, carbon dioxide, sulfur, etc.) are released during operational activities. The four significant environment spheres (atmosphere, hydrosphere, biosphere, and lithosphere) are negatively influenced by Thar coal mining. The second part of the analysis results shows that human needs and interests have a positive and significant relationship except for human health and safety with Sindh Engro coal mining. Environmental pollution can be controlled by utilizing environmentally friendly coal mining operations and technologies. Plantation and ecological normalization can protect the species, flora, and fauna of the Thar Desert. The government of Pakistan and the provincial government of Sind should strictly check the adaptation of environmental standards. Furthermore, the researchers should explore the environmental issues and solutions so that coal mining becomes a cost-efficient and environmental-friendly energy source in Pakistan.
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Bulhakov, Ruslan, Vyacheslav Holovan, Artur Holovan e Stanislav Nikul. "MODEL OF WEAPONS AND MILITARY EQUIPMENT DEVELOPMENT". Collection of scientific works of Odesa Military Academy, n. 15 (30 settembre 2021): 58–64. http://dx.doi.org/10.37129/2313-7509.2021.15.58-64.
Testo completoAbstract (sommario):
At present, in the field of view of domestic researchers are left without consideration of the complex indicators of the weapons system and military equipment, as well as the possibility of managerial influence on them. A complex system of armaments and military equipment has a significant number of interrelated properties and qualities, among which it is necessary to distinguish between simple and integral qualities. To describe the processes of development of the armament system and military equipment, which include not only quantitative changes in it, but also qualitatively new behavior, nonlinear mathematical models are used. Any system of armaments and military equipment inevitably receives excitement of various types. Such excitations can be either external influences, due to random or systematic changes in the environment, or internal fluctuations that occur in the system itself as a result of the interaction of elements. The study raises a range of issues of "quantitative integration" or quantitative study of dynamic weapons systems and military equipment, as well as the number and nature of the equilibrium of the dynamic weapons system and military equipment, the presence of bifurcation points (intersections of decisions). The article proposes a mathematical model of development of the weapons system and military equipment focused on the study of integrated indicators and properties of the system, built on the basis of a conceptual model of development and a model of the process of self-organization. The presented model takes into account not only quantitative changes in the given system, but also qualitatively new behavior of the system, dynamics of structural changes and entropy of the system; also in the given model attention is paid to processes of self-instruction of system. Keywords: armament and military equipment, development, model.
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Landsburg, Alexander C., Roderick A. Barr, Larry Daggett, Wei-Yuan Hwang, Bent Jakobsen, Mike Morris e Lou Vest. "Critical Needs for Ship Maneuverability: Lessons From the Houston Ship Channel Full-Scale Maneuvering Trials". Marine Technology and SNAME News 42, n. 01 (1 gennaio 2005): 11–20. http://dx.doi.org/10.5957/mt1.2005.42.1.11.
Testo completoAbstract (sommario):
"I think the architects and engineers that design ships for the sea, where they spend 99% of their time, forget that at some point they still have to get up the ditches to load or discharge their cargo. Someday when a high-profile accident does occur, ship builders might even be brought into the civil arena and found criminally negligent and liable for building underpowered and poor handling ships."A pilot's view The Standards for Ship Maneuverability approved by the International Maritime Organization (IMO) in 2002 represent a significant step forward in ensuring adequate maneuverability of ships. The Standards provide numerical criteria for assessing the adequacy of maneuverability in deep, unrestricted water at sea speed. Explanatory notes to the Standards provide useful guidelines to the assessment and validation process that help with various issues, such as adjusting full-scale trial results for environmental and loading conditions. Major issues exist, however. In question is the ability of the standards to ensure adequate maneuverability in shallow, restricted, and congested waterways under vessel meeting and passing conditions with the interaction effects, bank suction, and other situations that are encountered in normal port, harbor, and waterway operations. Historically, even in shallow water that is unrestricted, only a couple of ship trials have ever been conducted due to the great cost to prepare for such tests. The lack of accurate full-scale data has seriously limited the accuracy capable of being built into mathematical prediction models. Recently, however, revolutionary positioning technology has enabled collecting highly accurate track and vertical position data on ships operating in shallow and restricted water, with and without interacting ship traffic. Accurate mathematical modeling of ship operations in complex harbors and waterways has become a critical need, and now the possibility of advancing the science finally exists. With accurate full-scale trials data and improved prediction techniques, such as computational fluid dynamics, such ability now seems attainable.
22
Mohapatra, Sarat Chandra, Hafizul Islam, Thiago S. Hallak e C. Guedes Soares. "Solitary Wave Interaction with a Floating Pontoon Based on Boussinesq Model and CFD-Based Simulations". Journal of Marine Science and Engineering 10, n. 9 (5 settembre 2022): 1251. http://dx.doi.org/10.3390/jmse10091251.
Testo completoAbstract (sommario):
A mathematical model of solitary wave interaction with a pontoon-type rigid floating structure over a flat bottom is formulated based on Boussinesq-type equations under weakly nonlinear dispersive waves. Based on the higher-order Boussinesq equations, the solitary wave equation is derived, and a semi-analytical solution is obtained using the perturbation technique. On the other hand, brief descriptions of the application of wave2Foam and OceanWave3D on the aforementioned problem are presented. The analytical solitary wave profiles in the outer region are compared with Computational Fluid Dynamics (CFD) and OceanWave 3D model simulations in different cases. The comparison shows a good level of agreement between analytical, wave2Foam, and OceanWave3D. In addition, based on the wave2Foam and coupled OceanWave3D model, the horizontal, vertical wave forces, and the pressure distributions around the pontoon are analysed. Further, the effect of the Ursell number, pontoon length, and water depth on the solitary wave profiles are analysed based on the analytical solution. The paper validates each of the three models and performs intercomparison among them to assess their fidelity and computational burden.
23
Starchenko, A. V., A. A. Bart, L. I. Kizhner e E. A. Danilkin. "MESOSCALE METEOROLOGICAL MODEL TSUNM3 FOR THE STUDY AND FORECAST OF METEOROLOGICAL PARAMETERS OF THE ATMOSPHERIC SURFACE LAYER OVER A MAJOR POPULATION CENTER". Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, n. 66 (2020): 35–55. http://dx.doi.org/10.17223/19988621/66/3.
Testo completoAbstract (sommario):
The paper describes the mathematical formulation and numerical method of the TSUNM3 high-resolution mesoscale meteorological model being developed at Tomsk State University. The model is nonhydrostatic and includes three-dimensional nonstationary equations of hydrothermodynamics of the atmospheric boundary layer with parameterization of turbulence, moisture microphysics, long-wave and short-wave (solar) radiation, and advective and latent heat flows in the atmosphere and at the boundary of its interaction with the underlying surface. The numerical algorithm is constructed using structured grids with uniform spacing in horizontal directions and condensing to the Earth surface in the vertical direction. When approximating the differential formulation of the problem, the finite volume method with the second order approximation in the spatial variables is used. Explicit-implicit approximations in time (Adams–Bashforth and Crank–Nicolson) are used to achieve second-order accuracy in time. The paper presents results of numerical forecasting of the main meteorological parameters of the atmosphere (temperature, humidity, wind speed and direction) and precipitation in different seasons in the Siberian region. The models were tested with the help of observations obtained using the Volna-4M sodar, MTR-5 temperature profile meter, and Meteo-2 ultrasonic weather stations of the Atmosfera Collective Use Center. The improved TSUNM3 model is shown to adequately reflect the precipitation time and intensity. However, in some cases, the times of its beginning and end do not always coincide, the difference can reach several hours. The precipitation phase state is reflected reliably. Over 70% of precipitation cases are confirmed by numerical calculations. The model satisfactorily predicts temperature and humidity characteristics. The quality of the precipitation forecast model is comparable to the modern mesoscale models, such as the Weather Research and Forecasting (WRF) model.
24
Fong, Peter. "Influence Of Ice Sheets On Climate and Ice-Sheet Dynamics". Annals of Glaciology 14 (1990): 335. http://dx.doi.org/10.3189/s026030550000896x.
Testo completoAbstract (sommario):
The important role played by ice on climate is recognized in the ice–albedo feedback effect which is incorporated in most climate models. But the ice under consideration is two-dimensional and only its surface area enters into the interaction. Whereas this applies well to the seasonal ice and sea ice, it does not to the permanent ice sheets on earth because they are three-dimensional. A new feature is the ice flow down the ice-sheet slope. This increases the amount of ice on the ice-sheet periphery above that produced by local precipitation that is considered in most climate models. As a result the ice–albedo effect will be greater than that given in most climate models. The latter (a positive feedback) is generally smaller than the major negative feedback due to the infrared effect and therefore stable equilibrium is achieved in most climate models. When the positive feedback is thus increased to an amount equal to the infrared negative feedback, stable equilibrium is destroyed and the system changes to netural equilibrium – a mildly unstable form. This may be just what is necessary to explain the advance and retreat of the ice sheets, which cannot be explained by most climate models because in stable equilibrium an ice sheet cannot advance and retreat.The advance and retreat can be proven to be the manifestation of a neutral equilibrium. At any instant of time in an ice age, including the present time, the climate system is nearly in equilibrium. But as time goes on the equilibrium point shifts continuously, reflecting the advance of the ice sheet and the cooling of the ocean. Thus an ice age is represented by a continuous sequence of equilibrium points, which, by definition, constitutes a netural equilibrium. The argument is reinforced by the observation that the “cause” of ice ages is a very small perturbation – the variation of the eccentricity of the earth orbit. According to most climate models, this effect is one order of magnitude too small to generate the climate changes in an ice age. On the other hand in a neutral equilibrium a very weak perturbation can generate slow progressive changes, like the rolling of a cylinder on a plane. As a matter of fact, the small periodic changes of the eccentricity pace the advance and retreat of the ice sheets almost in phase; this is not possible in stable and unstable equilibrium and can be possible only in neutral equilibrium. The empirical conclusion of neutral equilibrium is solidly established. Any theory and any climate model must accommodate this fact.A deeper understanding requires the pinpointing of the physical origin of the meutral equilibrium. The origin can be shown, though not obviously, to be just the phase equilibrium of water and ice, which is quasi-static and may be considered as neutral equilibrium in a mechanical analogy. The argument is complicated by the fact that the temperature does not remain constant as expected in phase equilibrium but does decrease in an ice age. However, this can be accounted for by the complication of the albedo effect. Hypothetically if ice were brown and without albedo effect, then in an ice age the temperature would not decrease and the situation would be just like ice-water phase equilibrium. The physical origin of neutral equilibrium clarifies the fundamental principle but is not necessary for the mathematical formulation of a dynamic theory of the ice sheets that is given as follows. Instead neutral equilibrium emerges naturally from that theory and the advance and retreat can be explained readily.Most climate models are static models which cannot explain the advance and retreat – a manifestly dynamic process. A simple but adequate dynamic theory can be formulated considering the ice volume V(t) and the ocean surface temperature T(t) as the basic dynamic variables. The equations for their changes can be written down, making use of the latent heat of fusion of ice and the sensible heat capacity of the ocean mixed layer. Albedo positive feedback and infrared negative feedback will be included in the heat balance. The three-dimensional effect of the ice sheet will be introduced in the albedo effect. This involves the geometry of the ice sheet which will be specified in a constraint equation. Then a closed, deterministic set of intergral-differential equations may be formulated to describe the dynamics of the ice sheets. The equations may be solved without adjustable parameters. The solutions agree with the observed advance and retreat of ice sheets and the cooling and warming of the ocean. A close examination of the feedbacks involved reveals that the dynamics is indeed like a mechanical system in neutral equilibrium. However, the detailed mathematical theory shows that the netural equilibrium changes to stable when the ice sheets reach the middle latitudes. They thus stop there in maximum glaciation.There is no limit on the other end. The northern ice sheet did melt completely. So could the Antarctic ice sheet though it has not in the ice ages. But before the Pleistocene in 99% of the geological time the earth was free of ice sheets. Then, why did the “cause” of ice ages, the eccentricity variations, not generate ice ages in 99% of the earth history? Ice and water can co-exist (in equilibrium) only under unusual conditions, which are not fulfilled generally. But in recent geological times Antarctica drifted to the pole position and high mountains arose on the continents so that permanent ice can survive the summer season and accumulate year after year. Most important, the CO2 content in the atmosphere has been decreasing (Budyko, 1974), cooling down the earth. Eventually the earth was cool enough in Pleistocene to satisfy the neutral equilibrium condition. Then the ice ages began.But we are now burning fossil fuels to put CO2 back into the atmosphere, going back to pre-Pleistocene conditions. The Antarctic ice sheet will melt away; this will be the principal result of the greenhouse effect. However, current discussion of the greenhouse effect deals with only the warming of the earth and neglects the more serious effect of the melting of the Antarctic ice sheet because climatologists overlooked the effect of ice sheets on climate. This study will change the outlook.
25
Fong, Peter. "Influence Of Ice Sheets On Climate and Ice-Sheet Dynamics". Annals of Glaciology 14 (1990): 335. http://dx.doi.org/10.1017/s026030550000896x.
Testo completoAbstract (sommario):
The important role played by ice on climate is recognized in the ice–albedo feedback effect which is incorporated in most climate models. But the ice under consideration is two-dimensional and only its surface area enters into the interaction. Whereas this applies well to the seasonal ice and sea ice, it does not to the permanent ice sheets on earth because they are three-dimensional. A new feature is the ice flow down the ice-sheet slope. This increases the amount of ice on the ice-sheet periphery above that produced by local precipitation that is considered in most climate models. As a result the ice–albedo effect will be greater than that given in most climate models. The latter (a positive feedback) is generally smaller than the major negative feedback due to the infrared effect and therefore stable equilibrium is achieved in most climate models. When the positive feedback is thus increased to an amount equal to the infrared negative feedback, stable equilibrium is destroyed and the system changes to netural equilibrium – a mildly unstable form. This may be just what is necessary to explain the advance and retreat of the ice sheets, which cannot be explained by most climate models because in stable equilibrium an ice sheet cannot advance and retreat. The advance and retreat can be proven to be the manifestation of a neutral equilibrium. At any instant of time in an ice age, including the present time, the climate system is nearly in equilibrium. But as time goes on the equilibrium point shifts continuously, reflecting the advance of the ice sheet and the cooling of the ocean. Thus an ice age is represented by a continuous sequence of equilibrium points, which, by definition, constitutes a netural equilibrium. The argument is reinforced by the observation that the “cause” of ice ages is a very small perturbation – the variation of the eccentricity of the earth orbit. According to most climate models, this effect is one order of magnitude too small to generate the climate changes in an ice age. On the other hand in a neutral equilibrium a very weak perturbation can generate slow progressive changes, like the rolling of a cylinder on a plane. As a matter of fact, the small periodic changes of the eccentricity pace the advance and retreat of the ice sheets almost in phase; this is not possible in stable and unstable equilibrium and can be possible only in neutral equilibrium. The empirical conclusion of neutral equilibrium is solidly established. Any theory and any climate model must accommodate this fact. A deeper understanding requires the pinpointing of the physical origin of the meutral equilibrium. The origin can be shown, though not obviously, to be just the phase equilibrium of water and ice, which is quasi-static and may be considered as neutral equilibrium in a mechanical analogy. The argument is complicated by the fact that the temperature does not remain constant as expected in phase equilibrium but does decrease in an ice age. However, this can be accounted for by the complication of the albedo effect. Hypothetically if ice were brown and without albedo effect, then in an ice age the temperature would not decrease and the situation would be just like ice-water phase equilibrium. The physical origin of neutral equilibrium clarifies the fundamental principle but is not necessary for the mathematical formulation of a dynamic theory of the ice sheets that is given as follows. Instead neutral equilibrium emerges naturally from that theory and the advance and retreat can be explained readily. Most climate models are static models which cannot explain the advance and retreat – a manifestly dynamic process. A simple but adequate dynamic theory can be formulated considering the ice volume V(t) and the ocean surface temperature T(t) as the basic dynamic variables. The equations for their changes can be written down, making use of the latent heat of fusion of ice and the sensible heat capacity of the ocean mixed layer. Albedo positive feedback and infrared negative feedback will be included in the heat balance. The three-dimensional effect of the ice sheet will be introduced in the albedo effect. This involves the geometry of the ice sheet which will be specified in a constraint equation. Then a closed, deterministic set of intergral-differential equations may be formulated to describe the dynamics of the ice sheets. The equations may be solved without adjustable parameters. The solutions agree with the observed advance and retreat of ice sheets and the cooling and warming of the ocean. A close examination of the feedbacks involved reveals that the dynamics is indeed like a mechanical system in neutral equilibrium. However, the detailed mathematical theory shows that the netural equilibrium changes to stable when the ice sheets reach the middle latitudes. They thus stop there in maximum glaciation. There is no limit on the other end. The northern ice sheet did melt completely. So could the Antarctic ice sheet though it has not in the ice ages. But before the Pleistocene in 99% of the geological time the earth was free of ice sheets. Then, why did the “cause” of ice ages, the eccentricity variations, not generate ice ages in 99% of the earth history? Ice and water can co-exist (in equilibrium) only under unusual conditions, which are not fulfilled generally. But in recent geological times Antarctica drifted to the pole position and high mountains arose on the continents so that permanent ice can survive the summer season and accumulate year after year. Most important, the CO2 content in the atmosphere has been decreasing (Budyko, 1974), cooling down the earth. Eventually the earth was cool enough in Pleistocene to satisfy the neutral equilibrium condition. Then the ice ages began. But we are now burning fossil fuels to put CO2 back into the atmosphere, going back to pre-Pleistocene conditions. The Antarctic ice sheet will melt away; this will be the principal result of the greenhouse effect. However, current discussion of the greenhouse effect deals with only the warming of the earth and neglects the more serious effect of the melting of the Antarctic ice sheet because climatologists overlooked the effect of ice sheets on climate. This study will change the outlook.
26
He, Wei, Jinyu Lei, Xiumin Chu, Shuo Xie, Cheng Zhong e Zhixiong Li. "A Visual Analysis Approach to Understand and Explore Quality Problems of AIS Data". Journal of Marine Science and Engineering 9, n. 2 (13 febbraio 2021): 198. http://dx.doi.org/10.3390/jmse9020198.
Testo completoAbstract (sommario):
Low quality automatic identification system (AIS) data often mislead analysts to a misunderstanding of ship behavior analysis and to making incorrect navigation risk assessments. It is therefore necessary to accurately understand and judge the quality problems in AIS data before a further analysis of ship behavior. Outliers were filtered in the existing methods of AIS quality analysis based only on mathematical models where AIS data related quality problems are not utilized and there is a lack of visual exploration. Thus, the human brain’s ability cannot be fully utilized to think visually and for reasoning. In this regard, a visual analytics (VA) approach called AIS Data Quality visualization (ADQvis) was designed and implemented here to support evaluations and explorations of AIS data quality. The system interface is overviewed and then the visualization model and corresponding human-computer interaction method are described in detail. Finally, case studies were carried out to demonstrate the effectiveness of our visual analytics approach for AIS quality problems.
27
Waghmare, Roji B., Pramod V. Mahajan e Uday S. Annapure. "Modelling the Influence of Time and Temperature on Respiration Rate of Fresh Fig and Diced Papaya". International Journal of Food Engineering 10, n. 1 (10 gennaio 2014): 89–96. http://dx.doi.org/10.1515/ijfe-2013-0047.
Testo completoAbstract (sommario):
Abstract For the design of modified atmosphere packaging, it is necessary to know the influence of time and temperature on the respiration rate (RR) of fresh produce. RR of fresh fig and diced papaya was measured at three temperatures (10, 20 and 30°C) for storage time of 1–5 days under aerobic condition using closed system method. The aim was to determine the influences of storage temperature and time on RR of fresh fig and diced papaya. It develops and validates a combined predictive mathematical model based on the Arrhenius equation and Weibull distribution model. Temperature and time had a significant effect on RR. of fresh fig and diced papaya ranged from 16.2 to 45 and 25.5 to 114.9 ml kg–1 h–1 and ranged from 11.5 to 51.9 and 23.9 to 113 ml kg–1 h–1, respectively, over the three storage temperatures tested. RR increased significantly four- to fivefolds with increase in temperature from 10 to 30°C. Temperature and the interaction of time and temperature had the significant effect on and . Arrhenius and Weibull distribution models successfully fitted the experimental data, adequately describing the influence of temperature and time on RR of fresh fig and diced papaya. This model can be used to predict RR at different temperature and time. The model which was tested at 15°C for its validity showed good agreement between experimental and predicted data. These models would help to choose the optimum packaging for selected fruits.
28
Rastigejev, Yevgenii, e Sergey A. Suslov. "Investigation of Sea Spray Effect on the Vertical Momentum Transport Using an Eulerian Multifluid-Type Model". Journal of Physical Oceanography 52, n. 1 (gennaio 2022): 99–117. http://dx.doi.org/10.1175/jpo-d-21-0127.1.
Testo completoAbstract (sommario):
Abstract The Eulerian multifluid mathematical model is developed to describe the marine atmospheric boundary layer laden with sea spray under the high-wind condition of a hurricane. The model considers spray and air as separate continuous interacting turbulent media and employs the multifluid E–ϵ closure. Each phase is described by its own set of coupled conservation equations and characterized by its own velocity. Such an approach enables us to accurately quantify the interaction between spray and air and pinpoint the effect of spray on the vertical momentum transport much more precisely than could be done with traditional mixture-type approaches. The model consistently quantifies the effect of spray inertia and the suppression of air turbulence due to two different mechanisms: the turbulence attenuation, which results from the inability of spray droplets to fully follow turbulent fluctuations, and the vertical transport of spray against the gravity by turbulent eddies. The results of numerical and asymptotic analyses show that the turbulence suppression by spray overpowers its inertia several meters above wave crests, resulting in a noticeable wind acceleration and the corresponding reduction of the drag coefficient from the reference values for a spray-free atmosphere. This occurs at much lower than predicted previously spray volume fraction values of ∼10−5. The falloff of the drag coefficient from its reference values is more strongly pronounced at higher altitudes. The drag coefficient reaches its maximum at spray volume fraction values of ∼10−4, which is several times smaller than predicted by mixture-type models.
29
Pasricha, M. S. "Effect of Damping on Parametrically Excited Torsional Vibrations of Reciprocating Engines Including Gas Forces". Journal of Ship Research 50, n. 02 (1 giugno 2006): 147–57. http://dx.doi.org/10.5957/jsr.2006.50.2.147.
Testo completoAbstract (sommario):
In recent years, several cases of secondary resonance have been found in torsional vibrations of crankshaft systems. In some reciprocating large marine diesel engine systems, these effects have been a contributing factor of catastrophic failures. In these instances, design based on invariable inertia characteristics of the systems and using constant damping could not project the existence of adverse situations that led to excessively large motions. Most of the mathematical models considered thus far either give limited information on the effects of damping or restrict the analysis to an undamped variable inertia system with gas forces to avoid complexities. As a result, these models do not highlight all the consequences of such motion. This paper presents the equation of motion with key nondimensional parameters to include both damping and external excitations in order to predict the complete response of an equivalent single-cylinder engine system. Additionally, the nondimensional mathematical model presented in this paper allows development of design charts and brings the analysis closer to becoming an effective design tool. This model extends the previous analytical model by the author (2001) to include the effects of damping and gas forces acting on the system and captures many of the important concepts of time-dependent inertia systems. The complex waveform responses are examined within the range of engine speeds at which inexplicable crankshaft failures are known to have occurred. The investigations are conducted to study the interaction of secondary resonance effects with harmonic excitations for variation in damping and inertia ratios. These studies show that the observed effect is a natural physical phenomenon arising from the variable inertia characteristics of the system, and under certain circumstances it can have a serious impact on torsional vibration. The conclusions reached in this paper differ from those of Draminsky (1961) and Hesterman and Stone (1994). Comments on these differences are also included.
30
Buendía, C., A. Kleidon e A. Porporato. "The role of tectonic uplift, climate and vegetation in the long-term terrestrial phosphorous cycle". Biogeosciences Discussions 7, n. 1 (14 gennaio 2010): 301–33. http://dx.doi.org/10.5194/bgd-7-301-2010.
Testo completoAbstract (sommario):
Abstract. Phosphorus (P) is a crucial element for life and therefore for maintaining ecosystem productivity. Its local availability to the terrestrial biosphere results from the interaction between climate, tectonic uplift, atmospheric transport and biotic cycling. Here we present a mathematical model that describes the terrestrial P-cycle in a simple but comprehensive way. The resulting dynamical system can be solved analytically for steady-state conditions, allowing us to test the sensitivity of the P-availability to the key parameters and processes. Given constant inputs, we find that humid ecosystems exhibit lower P availability due to higher runoff and losses, and that tectonic uplift is a fundamental constraint. In particular, we find that in humid ecosystems the biotic cycling seem essential to maintain long-term P-availability. The time-dependent P dynamics for the Franz Josef and Hawaii chronosequences show how tectonic uplift is an important constraint on ecosystem productivity, while hydroclimatic conditions control the P-losses and speed towards steady-state. The model also helps describe how with limited uplift and atmospheric input, as in the case of the Amazon Basin, ecosystems must rely on mechanisms that enhance P-availability and retention. Our analysis underlines the need to include the P cycle in global vegetation-atmosphere models for a reliable representation of the response of the terrestrial biosphere to global change.
31
Kaimov, Abylay, Yerzhan Syrgaliyev, Amandyk Tuleshov, Suleimen Kaimov, Talgat Kaiym, Aidarkhan Kaimov e Altynay Primbetova. "Creation of an innovative robot with a gripper for moving plant microshoots from the in vitro transport tank to the working tank with soil ground at the stage of their adaptation in soil ground during microclonal reproduction". Eastern-European Journal of Enterprise Technologies 1, n. 7(115) (28 febbraio 2022): 48–58. http://dx.doi.org/10.15587/1729-4061.2022.253135.
Testo completoAbstract (sommario):
The industrial development of cities is the main cause of the destruction and degradation of natural resources around the world. Urbanization negatively affects the species composition of plants, the atmosphere and soil cover of areas of populated areas of large cities of the World. Tree plantations are the main mechanism for stabilizing the ecological situation in large cities and arid territories of the countries of the World. In this regard, in order to obtain a large number of genetically identical plants using their micropropagation, it is necessary to automate the main stages of this technological process. The result of the study is the creation of an adaptive phalanx gripper of a robotic complex for automating the technological process of handling operations. That will have a positive effect on solving the urgent problem of planting greenery in large cities and areas of arid territories not only in the Republic of Kazakhstan, but also in other countries of the World and represents a fundamentally new approach to solving the environmental problems of the Earth. The article substantiates various options for structural-kinematic schemes of the robot gripper, taking into account the stochastic conditions of its interaction with the overloaded object. Mathematical methods have been created for the selection and justification of the geometric, structural-kinematic and dynamic parameters of grippers for overloading plant microshoots and their computer 3D models. Software has been developed for modeling the functioning of a remotely controlled physical prototype of a mobile robot with an adaptive gripper for reloading microshoots from a transport tank to a cargo tank.
32
Moulin, A., e A. Wirth. "A Drag-Induced Barotropic Instability in Air–Sea Interaction". Journal of Physical Oceanography 44, n. 2 (1 febbraio 2014): 733–41. http://dx.doi.org/10.1175/jpo-d-13-097.1.
Testo completoAbstract (sommario):
Abstract A new mechanism that induces barotropic instability in the ocean is discussed. It is due to the air–sea interaction with a quadratic drag law and horizontal viscous dissipation in the atmosphere. The authors show that the instability spreads to the atmosphere. The preferred spatial scale of the instability is that of the oceanic baroclinic Rossby radius of deformation. It can only be represented in numerical models, when the dynamics at this scale is resolved in the atmosphere and ocean. The dynamics are studied using two superposed shallow water layers: one for the ocean and one for the atmosphere. The interaction is due to the shear between the two layers. The shear applied to the ocean is calculated using the velocity difference between the ocean and the atmosphere and the quadratic drag law. In one-way interaction, the shear applied to the atmosphere neglects the ocean dynamics; it is calculated using the atmospheric wind only. In two-way interaction, it is opposite to the shear applied to the ocean. In one-way interaction, the atmospheric shear leads to a barotropic instability in the ocean. The instability in the ocean is amplified, in amplitude and scale, in two-way interaction and also triggers an instability in the atmosphere.
33
Moreira, Virnei Silva, Luiz Antonio Candido, Debora Regina Roberti, Geovane Webler, Marcelo Bortoluzzi Diaz, Luis Gustavo Gonçalves de Gonçalves, Raphael Pousa e Gervásio Annes Degrazia. "Influence of Soil Properties in Different Management Systems: Estimating Soybean Water Changes in the Agro-IBIS Model". Earth Interactions 22, n. 4 (1 marzo 2018): 1–19. http://dx.doi.org/10.1175/ei-d-16-0033.1.
Testo completoAbstract (sommario):
Abstract The water balance in agricultural cropping systems is dependent on the physical and hydraulic characteristics of the soil and the type of farming, both of which are sensitive to the soil management. Most models that describe the interaction between the surface and the atmosphere do not efficiently represent the physical differences across different soil management areas. In this study, the authors analyzed the dynamics of the water exchange in the agricultural version of the Integrated Biosphere Simulator (IBIS) model (Agro-IBIS) in the presence of different physical soil properties because of the different long-term soil management systems. The experimental soil properties were obtained from two management systems, no tillage (NT) and conventional tillage (CT) in a long-term experiment in southern Brazil in the soybean growing season of 2009/10. To simulate NT management, this study modified the top soil layer in the model to represent the residual layer. Moreover, a mathematical adjustment to the computation of leaf area index (LAI) is suggested to obtain a better representation of the grain fill to the physiological maturity period. The water exchange dynamics simulated using Agro-IBIS were compared against experimental data collected from both tillage systems. The results show that the model well represented the water dynamics in the soil and the evapotranspiration (ET) in both management systems, in particular during the wet periods. Better results were found for the conventional tillage management system for the water balance. However, with the incorporation of a residual layer and soil properties in NT, the model improved the estimation of evapotranspiration by 6%. The ability of the Agro-IBIS model to estimate ET indicates its potential application in future climate scenarios.
34
Sinaga, Luhut Tumpal Parulian. "MODEL ANALITIK SLOSHING TANGKI- MUAT PADA OLAH GERAK KAPAL FLOATING LIQUEFIED NATURAL GAS (FLNG) = ANALITICAL MODEL OF SLOSHING IN STORAGE TANK ON FLOATING LIQUEFIED NATURAL GAS (FLNG) SHIP MOTION". Majalah Ilmiah Pengkajian Industri 9, n. 1 (16 giugno 2015): 1–12. http://dx.doi.org/10.29122/mipi.v9i1.90.
Testo completoAbstract (sommario):
Studies on the effect of sloshing motion and heave coupling picth after receiving an external force wage varying wave energy and angular variation headings. This study will conduct a study of physical model testing with mooring configuration and MAT-LAB program of mathematical models free floating barge matika mechanism through numerical simulations and computational fluid dynamic (CFD). This riset aims to observe and explain the effect of sloshing on ship motions and the interaction with the research methodology systematically carried through the calculation/numerical simulations (Mathematics and Computational Fluid Dynamics Laboratory), and the physical scale model testing (at Maneuvering and Ocean Engineering Basin).The results of the study through experiments and numerical phenomenon suggests that the effect of sloshing on the effect of ship motion can be well understood. Pressure due to the wave heading angle of 90 degrees gives a higher impact pressure. Style sloshing is not directly proportional to the amplitude of excitation. AbstrakKajian pengaruh dari sloshing terhadap gerakan kopel heave dan picth setelah menerima gaya external berupa energi gelombang yang bervariasi dan variasi sudut heading. Kajian ini akan melakukan kajian pengujian model fisik dengan konfigurasi tambat yang dan program matematik MAT-LAB dari model matematika free floating barge mechanism serta melalui simulasi numerik computational fluid dynamic (CFD).Penelitian bertujuan mengamati dan menjelaskan pengaruh sloshing terhadap gerakan kapal dan interaksi tersebut secara sistimatis dengan metodologi penelitian yang dilakukan melalui perhitungan/ simulasi numerik (mathematics laboratory dan computational fluid dynamics), dan pengujian model skala fisik (di maneuvering and ocean engineering basin). Konfigurasi geometri model yang disimulasikan dan diuji adalah tipe FLNG dengan tangki berisi muatan cair yang memungkinkan terdapat permukaan bebas.Hasil kajian melalui eksperimen dan numerik menunjukkan bahwa efek fenomena sloshing terhadap pengaruh gerakan kapal dapat diketahui dengan baik. Pada sudut heading 900 terdapat gerakan yang tidak jelas sehingga perlu adanya investigasi lebih lanjut. Persamaan nonlinier aliran sloshing sangat diperlukan untuk dapat menghitung besaran gerakan kapal. Tekanan akibat gelombang pada sudut heading 900 memberikan dampak tekanan yang lebih tinggi. Gaya sloshing tidak berbanding lurus dengan amplitudo eksitasi. Oleh karena itu, gerakan kapal ditambah dengan sloshing tidak bervariasi secara linier terhadap amplitudo gelombang.Â
35
MOSQUERA CUESTA, HERMAN J. "AN ORIGIN FOR THE MAIN PULSATION AND OVERTONES OF SGR1900+14 DURING THE AUGUST 27 (1998) SUPEROUTBURST". International Journal of Modern Physics D 14, n. 09 (settembre 2005): 1485–94. http://dx.doi.org/10.1142/s0218271805007012.
Testo completoAbstract (sommario):
The crucial observation on the occurrence of subpulses (overtones) in the Power Spectral Density of the August 27 (1998) event from SGR1900+14, as discovered by BeppoSAX,7 has received no consistent explanation in the context of the competing theories to explain the SGRs phenomenology: the magnetar and accretion-driven models. Based on the ultra-relativistic, ultracompact X-ray binary model introduced in the accompanying paper,20 I present here a self-consistent explanation for such an striking feature. I suggest that both the fundamental mode and the overtones observed in SGR1900+14 stem from pulsations of a massive white dwarf (WD). The fundamental mode (and likely some of its harmonics) is excited because of the mutual gravitational interaction with its orbital companion (a NS, envisioned here as point mass object) whenever the binary Keplerian orbital frequency is a multiple integer number (m) of that mode frequency.28 Besides, a large part of the powerful irradiation from the fireball-like explosion occurring on the NS (after partial accretion of disk material) is absorbed in different regions of the star driving the excitation of other multipoles,25,26 i.e., the overtones (fluid modes of higher frequency). Part of this energy is then reemitted into space from the WD surface or atmosphere. This way, the WD lightcurve carries with it the signature of these pulsations inasmuch the way as it happens with the Sun pulsations in Helioseismology. It is shown that our theoretical prediction on the pulsation spectrum agrees quite well with the one found by BeppoSAX,7 a feature confirmed by numerical simulations (Montgomery & Winget 2000).
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Krakauer, Nir Y., Michael J. Puma, Benjamin I. Cook, Pierre Gentine e Larissa Nazarenko. "Ocean–atmosphere interactions modulate irrigation's climate impacts". Earth System Dynamics 7, n. 4 (10 novembre 2016): 863–76. http://dx.doi.org/10.5194/esd-7-863-2016.
Testo completoAbstract (sommario):
Abstract. Numerous studies have focused on the local and regional climate effects of irrigated agriculture and other land cover and land use change (LCLUC) phenomena, but there are few studies on the role of ocean–atmosphere interaction in modulating irrigation climate impacts. Here, we compare simulations with and without interactive sea surface temperatures of the equilibrium effect on climate of contemporary (year 2000) irrigation geographic extent and intensity. We find that ocean–atmosphere interaction does impact the magnitude of global-mean and spatially varying climate impacts, greatly increasing their global reach. Local climate effects in the irrigated regions remain broadly similar, while non-local effects, particularly over the oceans, tend to be larger. The interaction amplifies irrigation-driven standing wave patterns in the tropics and midlatitudes in our simulations, approximately doubling the global-mean amplitude of surface temperature changes due to irrigation. The fractions of global area experiencing significant annual-mean surface air temperature and precipitation change also approximately double with ocean–atmosphere interaction. Subject to confirmation with other models, these findings imply that LCLUC is an important contributor to climate change even in remote areas such as the Southern Ocean, and that attribution studies should include interactive oceans and need to consider LCLUC, including irrigation, as a truly global forcing that affects climate and the water cycle over ocean as well as land areas.
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Wirth, Achim. "On fluctuating momentum exchange in idealised models of air–sea interaction". Nonlinear Processes in Geophysics 26, n. 4 (16 dicembre 2019): 457–77. http://dx.doi.org/10.5194/npg-26-457-2019.
Testo completoAbstract (sommario):
Abstract. The dynamics of three local models, for momentum transfer at the air–sea interface, is compared. The models differ by whether or not the ocean velocity is included in the shear calculation applied to the ocean and the atmosphere. All three cases are employed in climate or ocean simulations. Analytic calculations for the models with deterministic and random forcing (white and coloured) are presented. The short-term behaviour is similar in all models, with only small quantitative differences, while the long-term behaviour differs qualitatively between the models. The fluctuation–dissipation relation, which connects the fast atmospheric motion to the slow oceanic dynamics, is established for all models with random forcing. The fluctuation–dissipation theorem, which compares the response to an external forcing to internal fluctuations, is established for a white-noise forcing and a coloured forcing when the phase space is augmented by the forcing variable. Using results from numerical integrations of stochastic differential equations, we show that the fluctuation theorem, which compares the probability of positive to negative fluxes of the same magnitude, averaged over time intervals of varying lengths, holds for the energy gained by the ocean from the atmosphere.
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Karnauskas, Kristopher B., Raghu Murtugudde e Antonio J. Busalacchi. "Observing the Galápagos–EUC Interaction: Insights and Challenges". Journal of Physical Oceanography 40, n. 12 (1 dicembre 2010): 2768–77. http://dx.doi.org/10.1175/2010jpo4461.1.
Testo completoAbstract (sommario):
Abstract Although sustained observations yield a description of the mean equatorial current system from the western Pacific to the eastern terminus of the Tropical Atmosphere Ocean (TAO) array, a comprehensive observational dataset suitable for describing the structure and pathways of the Equatorial Undercurrent (EUC) east of 95°W does not exist and therefore climate models are unconstrained in a region that plays a critical role in ocean–atmosphere coupling. Furthermore, ocean models suggest that the interaction between the EUC and the Galápagos Islands (∼92°W) has a striking effect on the basic state and coupled variability of the tropical Pacific. To this end, the authors interpret historical measurements beginning with those made in conjunction with the discovery of the Pacific EUC in the 1950s, analyze velocity measurements from an equatorial TAO mooring at 85°W, and analyze a new dataset from archived shipboard ADCP measurements. Together, the observations yield a possible composite description of the EUC structure and pathways in the eastern equatorial Pacific that may be useful for model validation and guiding future observation.
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Hanna, Edward. "The role of Antarctic sea ice in global climate change". Progress in Physical Geography: Earth and Environment 20, n. 4 (dicembre 1996): 371–401. http://dx.doi.org/10.1177/030913339602000401.
Testo completoAbstract (sommario):
Taking a distinct interdisciplinary focus, a critical view is presented of the current state of research concerning Antarctic sea-ice / atmosphere / ocean interaction and its effect on climate on the interannual timescale, with particular regard to anthropogenic global warming. Sea-ice formation, morphology, thickness, extent, seasonality and distribution are introduced as vital factors in climatic feedbacks. Sea-ice / atmosphere interaction is next discussed, emphas izing its meteorological and topographical influences and the effects of and on polar cyclonic activity. This leads on to the central theme of sea ice in global climate change, which contains critiques of sea-ice climatic feedbacks, current findings on the representation of these feedbacks in global climatic models, and to what extent they are corroborated by observational evidence. Sea-ice / ocean interaction is particularly important. This is discussed with special reference to polynyas and leads, and the use of suitably coupled sea-ice / ocean models. A brief review of several possible climatic forcing factors is presented, which most highly rates a postulated ENSO-Antarctic sea-ice link. Sea-ice / atmosphere / ocean models need to be validated by adequate observations, both from satellites and ground based. In particular, models developed in the Arctic, where the observational network allows more reasonable validation, can be applied to the Antarctic in suitably modified form so as to account for unique features of the Antarctic cryosphere. Benefits in climatic modelling will be gained by treating Antarctic sea ice as a fully coupled component of global climate.
40
Kravtsov, S. K., W. K. Dewar, M. Ghil, P. S. Berloff e J. C. McWilliams. "North Atlantic climate variability in coupled models and data". Nonlinear Processes in Geophysics 15, n. 1 (18 gennaio 2008): 13–24. http://dx.doi.org/10.5194/npg-15-13-2008.
Testo completoAbstract (sommario):
Abstract. We show that the observed zonally averaged jet in the Northern Hemisphere atmosphere exhibits two spatial patterns with broadband variability in the decadal and inter-decadal range; these patterns are consistent with an important role of local, mid-latitude ocean–atmosphere coupling. A key aspect of this behaviour is the fundamentally nonlinear bi-stability of the atmospheric jet's latitudinal position, which enables relatively small sea-surface temperature anomalies associated with ocean processes to affect the large-scale atmospheric winds. The wind anomalies induce, in turn, complex three-dimensional anomalies in the ocean's main thermocline; in particular, they may be responsible for recently reported cooling of the upper ocean. Both observed modes of variability, decadal and inter-decadal, have been found in our intermediate climate models. One mode resembles North Atlantic tri-polar sea-surface temperature (SST) patterns described elsewhere. The other mode, with mono-polar SST pattern, is novel; its key aspects include interaction of oceanic turbulence with the large-scale oceanic flow. To the extent these anomalies exist, the interpretation of observed climate variability in terms of natural and human-induced changes will be affected. Coupled mid-latitude ocean-atmosphere modes do, however, suggest some degree of predictability is possible.
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Renault, Lionel, M. Jeroen Molemaker, Jonathan Gula, Sebastien Masson e James C. McWilliams. "Control and Stabilization of the Gulf Stream by Oceanic Current Interaction with the Atmosphere". Journal of Physical Oceanography 46, n. 11 (novembre 2016): 3439–53. http://dx.doi.org/10.1175/jpo-d-16-0115.1.
Testo completoAbstract (sommario):
AbstractThe Gulf Stream (GS) is known to have a strong influence on climate, for example, by transporting heat from the tropics to higher latitudes. Although the GS transport intensity presents a clear interannual variability, satellite observations reveal its mean path is stable. Numerical models can simulate some characteristics of the mean GS path, but persistent biases keep the GS separation and postseparation unstable and therefore unrealistic. This study investigates how the integration of ocean surface currents into the ocean–atmosphere coupling interface of numerical models impacts the GS. The authors show for the first time that the current feedback, through its eddy killing effect, stabilizes the GS separation and postseparation, resolving long-lasting biases in modeled GS path, at least for the Regional Oceanic Modeling System (ROMS). This key process should therefore be taken into account in oceanic numerical models. Using a set of oceanic and atmospheric coupled and uncoupled simulations, this study shows that the current feedback, by modulating the energy transfer from the atmosphere to the ocean, has two main effects on the ocean. On one hand, by reducing the mean surface stress and thus weakening the mean geostrophic wind work by 30%, the current feedback slows down the whole North Atlantic oceanic gyre, making the GS narrower and its transport weaker. Yet, on the other hand, the current feedback acts as an oceanic eddy killer, reducing the surface eddy kinetic energy by 27%. By inducing a surface stress curl opposite to the current vorticity, it deflects energy from the geostrophic current into the atmosphere and dampens eddies.
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Bishop, Stuart P., R. Justin Small, Frank O. Bryan e Robert A. Tomas. "Scale Dependence of Midlatitude Air–Sea Interaction". Journal of Climate 30, n. 20 (13 settembre 2017): 8207–21. http://dx.doi.org/10.1175/jcli-d-17-0159.1.
Testo completoAbstract (sommario):
Abstract It has traditionally been thought that midlatitude sea surface temperature (SST) variability is predominantly driven by variations in air–sea surface heat fluxes (SHFs) associated with synoptic weather variability. Here it is shown that in regions marked by the highest climatological SST gradients and SHF loss to the atmosphere, the variability in SST and SHF at monthly and longer time scales is driven by internal ocean processes, termed here “oceanic weather.” This is shown within the context of an energy balance model of coupled air–sea interaction that includes both stochastic forcing for the atmosphere and ocean. The functional form of the lagged correlation between SST and SHF allows us to discriminate between variability that is driven by atmospheric versus oceanic weather. Observations show that the lagged functional relationship of SST–SHF and SST tendency–SHF correlation is indicative of ocean-driven SST variability in the western boundary currents (WBCs) and the Antarctic Circumpolar Current (ACC). By applying spatial and temporal smoothing, thereby dampening the signature SST anomalies generated by eddy stirring, it is shown that the oceanic influence on SST variability increases with time scale but decreases with increasing spatial scale. The scale at which SST variability in the WBCs and the ACC transitions from ocean to atmosphere driven occurs at scales less than 500 km. This transition scale highlights the need to resolve mesoscale eddies in coupled climate models to adequately simulate the variability of air–sea interaction. Away from strong SST fronts the lagged functional relationships are indicative of the traditional paradigm of atmospherically driven SST variability.
43
Lloyd, Ian D., e Gabriel A. Vecchi. "Submonthly Indian Ocean Cooling Events and Their Interaction with Large-Scale Conditions". Journal of Climate 23, n. 3 (1 febbraio 2010): 700–716. http://dx.doi.org/10.1175/2009jcli3067.1.
Testo completoAbstract (sommario):
Abstract The Indian Ocean exhibits strong variability on a number of time scales, including prominent intraseasonal variations in both the atmosphere and ocean. Of particular interest is the south tropical Indian Ocean thermocline ridge, a region located between 12° and 5°S, which exhibits prominent variability in sea surface temperature (SST) due to dominant winds that raise the thermocline and shoal the mixed layer. In this paper, submonthly (less than 30 day) cooling events in the thermocline ridge region are diagnosed with observations and models, and are related to large-scale conditions in the Indo-Pacific region. Observations from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) satellite were used to identify 16 cooling events in the period 1998–2007, which on average cannot be fully accounted for by air–sea enthalpy fluxes. Analysis of observations and a hierarchy of models, including two coupled global climate models (GFDL CM2.1 and GFDL CM2.4), indicates that ocean dynamical changes are important to the cooling events. For extreme cooling events (above 2.5 standard deviations), air–sea enthalpy fluxes account for approximately 50% of the SST signature, and oceanic processes cannot in general be neglected. For weaker cooling events (1.5–2.5 standard deviations), air–sea enthalpy fluxes account for a larger fraction of the SST signature. Furthermore, it is found that cooling events are preconditioned by large-scale, low-frequency changes in the coupled ocean–atmosphere system. When the thermocline is unusually shallow in the thermocline ridge region, cooling events are more likely to occur and are stronger; these large-scale conditions are more (less) likely during La Niña (El Niño/Indian Ocean dipole) events. Strong cooling events are associated with changes in atmospheric convection, which resemble the Madden–Julian oscillation, in both observations and the models.
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Robertson, Andrew W. "Influence of Ocean–Atmosphere Interaction on the Arctic Oscillation in Two General Circulation Models". Journal of Climate 14, n. 15 (agosto 2001): 3240–54. http://dx.doi.org/10.1175/1520-0442(2001)014<3240:iooaio>2.0.co;2.
Testo completo
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Jansen, Malte F., Dietmar Dommenget e Noel Keenlyside. "Tropical Atmosphere–Ocean Interactions in a Conceptual Framework". Journal of Climate 22, n. 3 (1 febbraio 2009): 550–67. http://dx.doi.org/10.1175/2008jcli2243.1.
Testo completoAbstract (sommario):
Abstract Statistical analysis of observations (including atmospheric reanalysis and forced ocean model simulations) is used to address two questions: First, does an analogous mechanism to that of El Niño–Southern Oscillation (ENSO) exist in the equatorial Atlantic or Indian Ocean? Second, does the intrinsic variability in these basins matter for ENSO predictability? These questions are addressed by assessing the existence and strength of the Bjerknes and delayed negative feedbacks in each tropical basin, and by fitting conceptual recharge oscillator models, both with and without interactions among the basins. In the equatorial Atlantic the Bjerknes and delayed negative feedbacks exist, although weaker than in the Pacific. Equatorial Atlantic variability is well described by the recharge oscillator model, with an oscillatory mixed ocean dynamics–sea surface temperature (SST) mode present in boreal spring and summer. The dynamics of the tropical Indian Ocean, however, appear to be quite different: no recharge–discharge mechanism is found. Although a positive Bjerknes-like feedback from July to September is found, the role of heat content seems secondary. Results also show that Indian Ocean interaction with ENSO tends to damp the ENSO oscillation and is responsible for a frequency shift to shorter periods. However, the retrospective forecast skill of the conceptual model is hardly improved by explicitly including Indian Ocean SST. The interaction between ENSO and the equatorial Atlantic variability is weaker. However, a feedback from the Atlantic on ENSO appears to exist, which slightly improves the retrospective forecast skill of the conceptual model.
46
Liu, Bin, Huiqing Liu, Lian Xie, Changlong Guan e Dongliang Zhao. "A Coupled Atmosphere–Wave–Ocean Modeling System: Simulation of the Intensity of an Idealized Tropical Cyclone". Monthly Weather Review 139, n. 1 (1 gennaio 2011): 132–52. http://dx.doi.org/10.1175/2010mwr3396.1.
Testo completoAbstract (sommario):
Abstract A coupled atmosphere–wave–ocean modeling system (CAWOMS) based on the integration of atmosphere–wave, atmosphere–ocean, and wave–current interaction processes is developed. The component models consist of the Weather Research and Forecasting (WRF) model, the Simulating Waves Nearshore (SWAN) model, and the Princeton Ocean Model (POM). The coupling between the model components is implemented by using the Model Coupling Toolkit. The CAWOMS takes into account various wave-related effects, including wave state and sea-spray-affected sea surface roughness, sea spray heat fluxes, and dissipative heating in atmosphere–wave coupling. It also considers oceanic effects such as the feedback of sea surface temperature (SST) cooling and the impact of sea surface current on wind stress in atmosphere–ocean coupling. In addition, wave–current interactions, including radiation stress and wave-induced bottom stress, are also taken into account. The CAWOMS is applied to the simulation of an idealized tropical cyclone (TC) to investigate the effects of atmosphere–wave–ocean coupling on TC intensity. Results show that atmosphere–wave coupling strengthens the TC system, while the thermodynamic coupling between the atmosphere and ocean weakens the TC as a result of the negative feedback of TC-induced SST cooling. The overall effects of atmosphere–wave–ocean coupling on TC intensity are determined by the balance between wave-related positive feedback and the negative feedback attributable to TC-induced SST cooling.
47
Sen Gupta, Alexander, e Matthew H. England. "Coupled Ocean–Atmosphere Feedback in the Southern Annular Mode". Journal of Climate 20, n. 14 (15 luglio 2007): 3677–92. http://dx.doi.org/10.1175/jcli4200.1.
Testo completoAbstract (sommario):
Abstract Previous studies have demonstrated that while the Southern Annular Mode (SAM) is an intrinsic feature of the atmosphere, it projects strongly onto the ocean and sea ice properties and circulation. This study investigates the extent of “back interaction” whereby these oceanic SAM anomalies feed back to the atmosphere. A comparison between atmosphere-only and full coupled climate models demonstrates that air–sea interactions in the coupled system act to increase the persistence of the SAM in the atmosphere. To identify the nature of feedback from the ocean to the atmosphere, ensemble experiments are carried out in both atmosphere-only and full coupled models whereby a continuous SAM-like sea surface temperature (SST) anomaly is imposed. Both coupled and uncoupled experiments show a direct thermal response that affects the lower-tropospheric temperature and surface meridional winds. An indirect upper troposphere–wide response is also seen whose characteristics are sensitive to the coupling. For the uncoupled experiment a negative-phase SAM SST perturbation produces an indirect atmospheric response that projects strongly onto the SAM. A positive-phase anomaly, however, shows little robust response away from the local heating at the surface. The coupled experiments, however, do show linearity with respect to the sign of the anomaly. However, the response is considerably weaker than the uncoupled case and the projection of the response onto the SAM mode is poorer. Nonetheless the authors find a clear persistence of the SAM at interseasonal time scales that relies on air–sea coupling and cannot be reproduced in unforced atmosphere-only experiments. This demonstrates that the ocean plays a role in modulating the Southern Annular Mode at these time scales.
48
Grist, Jeremy P., Simon A. Josey, Adrian L. New, Malcolm Roberts, Torben Koenigk e Doroteaciro Iovino. "Increasing Atlantic Ocean Heat Transport in the Latest Generation Coupled Ocean-Atmosphere Models: The Role of Air-Sea Interaction". Journal of Geophysical Research: Oceans 123, n. 11 (novembre 2018): 8624–37. http://dx.doi.org/10.1029/2018jc014387.
Testo completo
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Dourado-Neto, D., D. A. Teruel, K. Reichardt, D. R. Nielsen, J. A. Frizzone e O. O. S. Bacchi. "Principles of crop modeling and simulation: I. uses of mathematical models in agricultural science". Scientia Agricola 55, spe (1998): 46–50. http://dx.doi.org/10.1590/s0103-90161998000500008.
Testo completoAbstract (sommario):
Modeling techniques applied to agriculture can be useful to define research priorities and understanding the basic interactions of the soil-plant-atmosphere system. Using a model to estimate the importance and the effect of certain parameters, a researcher can notice which factors can be most useful. The modeler should define his objectives before beginning his work and construct a model that fulfills the proposed objectives.
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Wirth, Achim. "A Fluctuation–Dissipation Relation for the Ocean Subject to Turbulent Atmospheric Forcing". Journal of Physical Oceanography 48, n. 4 (aprile 2018): 831–43. http://dx.doi.org/10.1175/jpo-d-17-0097.1.
Testo completoAbstract (sommario):
AbstractThe fluctuation–dissipation relation for a turbulent fluid layer (ocean) subject to frictional forcing by a superposed lighter fluid layer (atmosphere) in local models of air–sea dynamics is established. The fluctuation–dissipation relation reflects the fact that air–sea interaction not only injects energy in the ocean but also dissipates it. Energy injection and dissipation must therefore be related. The competition between the two processes determines the oceanic energy budget in the idealized dynamics considered here. When applying the fluctuation–dissipation relation to a two-dimensional, two-layer, Navier–Stokes model with turbulent dynamics, in the atmosphere and the ocean, coupled by a quadratic friction law, the friction parameter is estimated within 8% of the true value, while the estimation of the mass ratio between the atmosphere and the ocean fails, as the forcing time scale is not faster than the characteristic time scale of the atmospheric dynamics.