scholarly journals A radiative-convective model based on constrained maximum entropy production

2019 ◽  
Vol 10 (3) ◽  
pp. 365-378 ◽  
Author(s):  
Vincent Labarre ◽  
Didier Paillard ◽  
Bérengère Dubrulle
Keyword(s):  
Entropy Production ◽  
Maximum Entropy ◽  
Energy Flux ◽  
Radiative Forcing ◽  
Climate Models ◽  
Carbon Dioxide Concentration ◽  
Atmospheric Composition ◽  
Energy Fluxes ◽  
Maximum Entropy Production ◽  
Energy Gradient

Abstract. The representation of atmospheric convection induced by radiative forcing is a long-standing question mainly because turbulence plays a key role in the transport of energy as sensible heat, geopotential, and latent heat. Recent works have tried using the maximum entropy production (MEP) conjecture as a closure hypothesis in 1-D simple climate models to compute implicitly temperatures and the vertical energy flux. However, these models fail to reproduce realistic profiles. To solve the problem, we describe the energy fluxes as a product of a positive mass mixing coefficient with the corresponding energy gradient. This appears as a constraint which imposes the direction and/or limits the amplitude of the energy fluxes. It leads to a different MEP steady state which naturally depends on the considered energy terms in the model. Accounting for this additional constraint improves the results. Temperature and energy flux are closer to observations, and we reproduce stratification when we consider the geopotential. Variations in the atmospheric composition, such as a doubling of the carbon dioxide concentration, are also investigated.

scholarly journals A Radiative Convective Model based on constrained Maximum Entropy Production

2018 ◽  
Author(s):  
Vincent Labarre ◽  
Didier Paillard ◽  
Bérengère Dubrulle
Keyword(s):  
Entropy Production ◽  
Maximum Entropy ◽  
Energy Flux ◽  
Radiative Forcing ◽  
Climate Models ◽  
Carbon Dioxide Concentration ◽  
Atmospheric Composition ◽  
Energy Fluxes ◽  
Maximum Entropy Production ◽  
Energy Transfers

Abstract. The representation of atmospheric convection induced by radiative forcing is a longstanding question mainly because turbulence plays a key role in the transport of energy as sensible heat, geopotential and latent heat. Recent works have tried to use Maximum Entropy Production as a closure hypothesis in Simple Climate Models in order to compute implicitly temperatures and vertical energy flux. However, these models failed to compute realistic profiles. To solve this problem, we prescribe a simplified 1D mass scheme transport which ensures energy fluxes. The later appears as a mechanical constraint which imposes the direction and/or limits the amplitudes of energy fluxes. This leads to a different MEP steady state which depends on the considered energy transfers in the model. Results using such model are improved with respect to another model, not including such effect: temperature and energy flux are closer to the observations and we naturally reproduce stratification when we consider geopotential. Variations of the atmospheric composition, such as doubling of the carbon dioxide concentration, is also investigated.

scholarly journals A Maximum Entropy Production Hypothesis for Time Varying Climate Problems: Illustration on a Conceptual Model for the Seasonal Cycle

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 966
Author(s):  
Vincent Labarre ◽  
Didier Paillard ◽  
Bérengère Dubrulle
Keyword(s):  
Energy Balance ◽  
Entropy Production ◽  
Conceptual Model ◽  
Maximum Entropy ◽  
Seasonal Cycle ◽  
Ground Temperature ◽  
Time Varying ◽  
Energy Fluxes ◽  
Maximum Entropy Production ◽  
Energy Balance Models

We investigated the applicability of the maximum entropy production hypothesis to time-varying problems, in particular, the seasonal cycle using a conceptual model. Contrarily to existing models, only the advective part of the energy fluxes is optimized, while conductive energy fluxes that store energy in the ground are represented by a diffusive law. We observed that this distinction between energy fluxes allows for a more realistic response of the system. In particular, a lag is naturally observed for the ground temperature. This study therefore shows that not all energy fluxes should be optimized in energy balance models using the maximum entropy production hypothesis, but only the fast convective (turbulent) part.

scholarly journals Maximum entropy production in environmental and ecological systems

2010 ◽  
Vol 365 (1545) ◽  
pp. 1297-1302 ◽  
Author(s):  
Axel Kleidon ◽  
Yadvinder Malhi ◽  
Peter M. Cox
Keyword(s):  
Entropy Production ◽  
Maximum Entropy ◽  
Atmospheric Composition ◽  
Maximum Entropy Production ◽  
Gaia Hypothesis ◽  
Atmosphere System ◽  
Global Biogeochemical Cycles ◽  
Principle Of Maximum ◽  
Thermodynamic Processes

The coupled biosphere–atmosphere system entails a vast range of processes at different scales, from ecosystem exchange fluxes of energy, water and carbon to the processes that drive global biogeochemical cycles, atmospheric composition and, ultimately, the planetary energy balance. These processes are generally complex with numerous interactions and feedbacks, and they are irreversible in their nature, thereby producing entropy. The proposed principle of maximum entropy production (MEP), based on statistical mechanics and information theory, states that thermodynamic processes far from thermodynamic equilibrium will adapt to steady states at which they dissipate energy and produce entropy at the maximum possible rate. This issue focuses on the latest development of applications of MEP to the biosphere–atmosphere system including aspects of the atmospheric circulation, the role of clouds, hydrology, vegetation effects, ecosystem exchange of energy and mass, biogeochemical interactions and the Gaia hypothesis. The examples shown in this special issue demonstrate the potential of MEP to contribute to improved understanding and modelling of the biosphere and the wider Earth system, and also explore limitations and constraints to the application of the MEP principle.

scholarly journals Vertical Temperature Profiles at Maximum Entropy Production with a Net Exchange Radiative Formulation*

2013 ◽  
Vol 26 (21) ◽  
pp. 8545-8555 ◽  
Author(s):  
Corentin Herbert ◽  
Didier Paillard ◽  
Bérengère Dubrulle
Keyword(s):  
Entropy Production ◽  
Climate Models ◽  
Carbon Dioxide Concentration ◽  
Small Time ◽  
Atmospheric Composition ◽  
Alternative View ◽  
Entropy Production Rate ◽  
Temperature Profiles ◽  
Vertical Temperature ◽  
Convective Flux

Abstract Like any fluid heated from below, the atmosphere is subject to vertical instability that triggers convection. Convection occurs on small time and space scales, which makes it a challenging feature to include in climate models. Usually subgrid parameterizations are required. Here, an alternative view based on a global thermodynamic variational principle is developed. Convective flux profiles and temperature profiles at steady state are computed in an implicit way by maximizing the associated entropy production rate. Two settings are examined, corresponding respectively to an idealized case of a gray atmosphere and a realistic case based on a net exchange formulation radiative scheme. In the second case, the effect of variations of the atmospheric composition, such as a doubling of the carbon dioxide concentration, is also discussed.

The mechanics of granitoid systems and maximum entropy production rates

2010 ◽  
Vol 368 (1910) ◽  
pp. 53-93 ◽  
Author(s):  
Bruce E. Hobbs ◽  
Alison Ord
Keyword(s):  
Entropy Production ◽  
Maximum Entropy ◽  
Melt Inclusions ◽  
Selection Process ◽  
Finite Thickness ◽  
Control Valve ◽  
Entropy Production Rate ◽  
Constitutive Behaviour ◽  
Maximum Entropy Production ◽  
Physical Height

A model for the formation of granitoid systems is developed involving melt production spatially below a rising isotherm that defines melt initiation. Production of the melt volumes necessary to form granitoid complexes within 10 4 –10 7 years demands control of the isotherm velocity by melt advection. This velocity is one control on the melt flux generated spatially just above the melt isotherm, which is the control valve for the behaviour of the complete granitoid system. Melt transport occurs in conduits initiated as sheets or tubes comprising melt inclusions arising from Gurson–Tvergaard constitutive behaviour. Such conduits appear as leucosomes parallel to lineations and foliations, and ductile and brittle dykes. The melt flux generated at the melt isotherm controls the position of the melt solidus isotherm and hence the physical height of the Transport/Emplacement Zone. A conduit width-selection process, driven by changes in melt viscosity and constitutive behaviour, operates within the Transport Zone to progressively increase the width of apertures upwards. Melt can also be driven horizontally by gradients in topography; these horizontal fluxes can be similar in magnitude to vertical fluxes. Fluxes induced by deformation can compete with both buoyancy and topographic-driven flow over all length scales and results locally in transient ‘ponds’ of melt. Pluton emplacement is controlled by the transition in constitutive behaviour of the melt/magma from elastic–viscous at high temperatures to elastic–plastic–viscous approaching the melt solidus enabling finite thickness plutons to develop. The system involves coupled feedback processes that grow at the expense of heat supplied to the system and compete with melt advection. The result is that limits are placed on the size and time scale of the system. Optimal characteristics of the system coincide with a state of maximum entropy production rate.

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