New publication by our postdoc Valerio Lembo and PI Valerio Lucarini

Finally published: A new tool for diagnosing several aspects of the thermodynamics of the climate state-of-the-art climate models - postdoc Valerio Lembo is very excited about this. We asked him a few questions:

• What is your work in TRR in general about?

I am a Postdoc researcher in the S1 subproject, dealing with diagnosis of climate model improvements. I work with datasets produced in climate model simulations, trying to detect inconsistencies and measure how model improvements eventually help in reducing or removing such inconsistencies.

• What is new about the tool you developed?

TheDiaTo gathers some existing techniques aimed at diagnosing the model performances in a quantitative way. These techniques are here related with each other in order to give an integrated view of the thermodynamics of the climate system. In other words, the climate at the global scale is seen as a thermal engine (as it is, for instance, the engine of a car, or a coal power plant), taking up heat from the Sun and converting it into work used to set the atmosphere and the oceans in motion. We adopt this basic framework as a robust constraint to the behavior of the system, and we measure if and how far is a simulated climate from such constraints.

• What to you hope will change in your field with your publication?

We have included the TheDiaTo collection in the ESMValTool community diagnostics, and we expect that it will be used in the analysis of the CMIP6 model outputs. These are the datasets based on which the 6th Assessment Report of the IPCC is being redacted, meaning that they are meant to set the new standard for our knowledge of climate change. We hope that this diagnosis effort will lead to a precise evaluation of model biases, and through that, to focused studies on how models code and structure can be consistently improved. The TRR181 is a unique opportunity to assess improvements in the ICON-FESOM coupled model, deriving from the inclusions of novel energetically consistent parametrizations of turbulent fluxes in the atmosphere and the ocean. The synergy between the parametrization and diagnostics development on one side, and the model implementation on the other side, is precisely the motivation behind the TRR181, and TheDiaTo will be essential in understanding the physics linking thermodynamics and the energy transfers in turbulent fluxes.

And what is it now all about? Find below the abstract for the publication:

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.

Download it here.