Vertical and horizontal processes in the global atmosphere and the maximum entropy production conjecture

Abstract

Abstract. The objective of this paper is to reconsider the Maximum Entropy Production conjecture (MEP) in the context of a very simple two-dimensional zonal-vertical climate model able to represent the total material entropy production due at the same time to both horizontal and vertical heat fluxes. MEP is applied first to a simple four-box model of climate which accounts for both horizontal and vertical material heat fluxes. It is shown that, under condition of fixed insolation, a MEP solution is found with reasonably realistic temperature and heat fluxes, thus generalising results from independent two-box horizontal or vertical models. It is also shown that the meridional and the vertical entropy production terms are independently involved in the maximisation and thus MEP can be applied to each subsystem with fixed boundary conditions. We then extend the four-box model by increasing its resolution, and compare it with GCM output. A MEP solution is found which is fairly realistic as far as the horizontal large scale organisation of the climate is concerned whereas the vertical structure looks to be unrealistic and presents seriously unstable features. This study suggest that the thermal meridional structure of the atmosphere is predicted fairly well by MEP once the insolation is given but the vertical structure of the atmosphere cannot be predicted satisfactorily by MEP unless constraints are imposed to represent the determination of longwave absorption by water vapour and clouds as a function of the state of the climate. Furthermore an order-of-magnitude estimate of contributions to the material entropy production due to horizontal and vertical processes within the climate system is provided by using two different methods. In both cases we found that approximately 40 mW m −2 K −1 of material entropy production is due to vertical heat transport and 5-7 mW m −2 K −1 to horizontal heat transport.

Upper-bound general circulation of coupled ocean–atmosphere: Part 1. Atmosphere

“…With the above perspective of the MEP, we shall next clarify some salient points in its application. First, since the MEP is a selection rule, it can be applied hierarchically, which justifies our deduction of first the global-mean temperature (Ou01) and then the meridional thermal field (Ou06); this approach is additionally supported by recent findings that the entropy productions are separately maximized by vertical and horizontal processes (Lucarini et al, 2011;Pascale et al, 2012). Second, since the turbulence is internal to the fluid, the MEP should apply to the atmosphere and ocean concurrently, which has obviated the need of extraneous closure assumptions (Paltridge, 1975;Noda and Tokioka, 1983;Obrien and Stephens, 1995) and simply resolved the system-boundary ambiguity (Virgo, 2010).…”

Global instability in the Ghil–Sellers model

“…4 (a) of (Lucarini et al, 2010)]. The EBM used here is not able to capture vertical processes, which, as discussed by Pascale et al (2012), give the strongest contribution to the entropy production. If now one computes in PlaSim, following , the contribution to the entropy production due to large scale horizontal processes, one obtains a bifurcation diagram [ Fig.…”

A Radiative Convective Model based on constrained Maximum Entropy Production

“…Former models (Ozawa and Ohmura , 1997;Pujol and Fort , 2002;Herbert et al , 2013) failed to reproduce realistic energy fluxes and temperature on the vertical (Pascale et al , 2012). This is due to the fact that some key ingredients was not considered.…”