Abstract
Abstract. This work presents the Thermodynamic Diagnostic Tool (TheDiaTo), a novel diagnostic tool for investigating the thermodynamics of climate systems with a wide range of applications, from sensitivity studies to model tuning. It includes a number of modules for assessing the internal energy budget, the hydrological cycle, the Lorenz energy cycle and the material entropy production. The routine takes as inputs energy fluxes at the surface and at the top of the atmosphere (TOA), which allows for the computation of energy budgets at the TOA, the surface and in the atmosphere as a residual. Meridional enthalpy transports are also computed from the divergence of the zonal mean energy budget from which the location and intensity of the maxima in each hemisphere are calculated. Rainfall, snowfall and latent heat fluxes are received as inputs for computation of the water mass and latent energy budgets. If a land–sea mask is provided, the required quantities are separately computed over continents and oceans. The diagnostic tool also computes the annual Lorenz energy cycle (LEC) and its storage and conversion terms by hemisphere and as a global mean. This is computed from three-dimensional daily fields of horizontal wind velocity and temperature in the troposphere. Two methods have been implemented for the computation of the material entropy production: one relying on the convergence of radiative heat fluxes in the atmosphere (indirect method) and the other combining the irreversible processes occurring in the climate system, particularly heat fluxes in the boundary layer, the hydrological cycle and the kinetic energy dissipation as retrieved from the residuals of the LEC (direct method). A version of these diagnostics has been developed as part of the Earth System Model eValuation Tool (ESMValTool) v2.0a1 in order to assess the performances of CMIP6 model simulations, and it will be available in the next release. The aim of this software is to provide a comprehensive picture of the thermodynamics of the climate system, as reproduced in the state-of-the-art coupled general circulation models. This can prove useful for better understanding anthropogenic and natural climate change, paleoclimatic climate variability, and climatic tipping points.
Highlights
The climate can be viewed as a forced, dissipative nonequilibrium system exchanging energy with the external environment
We focus on comparing a seven-member multi-model ensemble from CMIP5 under three different scenarios: “piControl”, denoting pre-industrial conditions, “historical”, i.e. a realistic forcing evolution for the 1870–2005 period, and “RCP8.5”, representing the 2005–2100 evolution of greenhouse gas (GHG) forcing under a business-as-usual emission scenario
We have presented TheDiaTo v1.0, a diagnostic tool for the study of different aspects of the thermodynamics of the climate system, with a focus on the atmosphere
Summary
The climate can be viewed as a forced, dissipative nonequilibrium system exchanging energy with the external environment. The inhomogeneous absorption of solar radiation is an ongoing source of available potential energy. The complex mixture of fluids is set into motion by the conversion of available potential into mechanical energy via a vast range of nonlinear processes. The kinetic energy is eventually dissipated through viscous stress and converted back into heat. Such processes can be described by taking advantage of the theory of the non-equilibrium thermodynamics of continuous multiphase media and, in particular, of fluids. The steady state is reached as a result of a potentially complex balance of positive and negative feedbacks and through the interplay of processes with very diverse timescales and physical underpinning mechanisms. The climate is a prime example of this, with observed variability extending over many orders of magnitude
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
