TheDiaTo (v1.0) – a new diagnostic tool for water, energy and entropy budgets in climate models

Abstract

This work presents a novel diagnostic tool for studying the thermodynamics of the 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, respectively. The routine receives as inputs energy fluxes at surface and at the Top-of-Atmosphere (TOA), for the computation of energy budgets at Top-of-Atmosphere (TOA), at the surface, and in the atmosphere as a residual. Meridional enthalpy transports are also computed from the divergence of the zonal mean energy budget fluxes; location and intensity of peaks in the two hemispheres are then provided as outputs. Rainfall, snowfall and latent heat fluxes are received as inputs for computing 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 Lorenz Energy Cycle (LEC) and its storage/conversion terms as annual mean global and hemispheric values. In order to achieve this, one needs to provide as input 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), one 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. A version of the diagnostic tool is included in the Earth System Model eValuation Tool (ESMValTool) community diagnostics, in order to assess the performances of soon available

Variability in the global energy budget and transports 1985–2017

“…Large-scale air-sea heat exchange can be critically controlled by small-scale ocean eddy motions called submesoscales, which dominate the ocean vertical motions (and hence fluxes) (Torres et al 2018;Klein et al 2019;Yu et al 2019). In terms of the large discrepancies of the TOA radiative fluxes and surface fluxes between observations, reanalysis and model simulations, the diagnostic tool of Lembo et al (2019b) may be employed to compare the results, and more in-depth studies are needed using the latest available data sets including the fifth-generation ECMWF reanalysis (ERA5). In this study, only ORAS5 data are employed for the calculation of ocean heat content and its change, so future work should incorporate more observation-based ocean analyses.…”

Earth System Model Evaluation Tool (ESMValTool) v2.0 – an extended set of large-scale diagnostics for quasi-operational and comprehensive evaluation of Earth system models in CMIP

“…Similar to Fig. 5 of Lembo et al (2019) and produced with recipe_thermodyn_diagtool.yml; see details in Sect. 3.2.4. the magnitude and sign of the atmospheric heat transports across the Equator, given its implications for atmospheric general circulation.…”

“…Similar to Fig. 8 of Lembo et al (2019) and produced with recipe_thermodyn_diagtool.yml; see details in Sect. 3.2.4.…”

ESMValTool v2.0 – Extended set of large-scale diagnostics for quasi-operational and comprehensive evaluation of Earth system models in CMIP

“…The diagnostic tool is run through the recipe recipe_thermodyn_diagtool.yml, where the user can also specify the options on which modules have to be run. An extensive explanation of the methods used and a discussion of 370 results with a subset of CMIP5 datasets can be found in Lembo et al (2019) who describe the Thermodynamic Diagnostic Tool (TheDiaTo) v1.0.…”