valeriolembo / thediato_v1.0

A collection of diagnostics for the study of the thermodynamics of the climate system

TheDiaTo v1.0

A collection of diagnostic for the study of the thermodynamics of the climate system

Author

Valerio Lembo* (Meteorological Institute, Hamburg University - [email protected])

*Currently at CNR-ISAC, Bologna, Italy - [email protected]

Introduction

The tool consists of four modules; one for the computation of energy budgets and transports, one for the water mass budgets (and related meridional transports), one for the Lorenz Energy Cycle (LEC), one for the material entropy production.

The first module is run by default, the others are optional. If the lsm option is set to true, the module 1 and the module 2 will be run with additional separate results over land and oceans.

• MODULE 1 (default): Earth's energy budgets from radiative and heat fluxes at Top-of-Atmosphere, at the surface and in the atmosphere (as a residual). Meridional transports, magnitude and location of the peaks in each hemisphere (only for heat transports) are also computed. The baroclinic efficiency is computed from TOA energy budgets, emission temperature (in turn retrieved from OLR) and near-surface temperature.

• MODULE 2 (optional): Water mass and latent energy budgets and meridional transports are computed from latent heat fluxes, snowfall and rainfall precipitation fluxes. Magnitude and location of the peaks in each hemisphere (only for heat transports) are also computed, as for module 1.

• MODULE 3 (optional): The Lorenz Energy Cycle (LEC) is computed in spectral components from near- surface temperatures, temperatures and the three components of velocities over pressure levels. The storage and conversion terms are directly computed, the sources and sinks are retrieved as residuals. Components are grouped into a zonal mean, stationary and transient eddy part.

• MODULE 4 (optional): The material entropy production is computed using the indirect method, the direct method or both (following Lucarini et al., 2014). For the indirect method a vertical and a horizontal component are provided. For the direct method, all components are combined, related to the hydrological cycle (attributable to evaporation, rainfall and snowfall precipitation, phase changes and potential energy of the droplet), to the sensible heat fluxes and to kinetic energy dissipation. For the latter the LEC computation is required, given that the strength of the LEC can be considered as equal to the kinetic energy dissipated to heating. If the option for module 3 is set to false, a reference value for the material entropy production related to the kinetic energy dissipation is provided.

Prerequisites

• Python v3.6x;
• CDO bindings for Python v1.5.x (update to latest available version);
• Matplotlib v2.x (at least 2.2);
• Numpy v1.15.x;
• Netcdf4 v1.4.2;

The program has been tested in an environment built through Anaconda3 repository: this might be necessary if the user is working on a server with no admin permissions. The above mentioned packages are retrieved from conda-forge collections. In case any question or problem arises, please contact the developers.

Content of the Package

• thermodyn_diagnostics.py: the main script;
• computations.py: contains all core computations;
• fluxogram.py: contains the instructions to produce a *.png picture with the diagram of the Lorenz Energy Cycle (LEC);
• fourier_coefficients.py: contains the script for producing Fourier coefficients from gridded data;
• lorenz_cycle.py: contains the functions for computation of the LEC;
• mkthe.py: contains the functions for computation of auxiliary variables;
• namelist.py: a namelist script to be adapted by the user;
• plot_script.py: contains functions for all plots (except the LEC diagram);

Usage

1. Obtain the datasets and store them as follows:

   a. The following variables are needed at the monthly resolution or higher (required variable name in brackets):

   • TOA shortwave radiation downwards (rsdt);

   • TOA shortwave radiation upwards (rsut);

   • TOA longwave radiation upwards (rlut);

   • Surface shortwave radiation downwards (rsds);

   • Surface shortwave radiation upwards (rsus);

   • Surface longwave radiation downwards (rlds);

   • Surface longwave radiation upwards (rlus);

   • Surface upward turbulent latent heat fluxes (hfls);

   • Surface upward turbulent sensible heat fluxes (hfss);

     FOR WATER MASS AND LATENT ENERGY BUDGET:

   • Precipitation flux (pr);

   • Snowfall flux (prsn);

   • Evaporation flux (evap); (if available, the evaporation flux is retrieved directly from the input fields, see paragraph 2);

     FOR MEP PRODUCTION WITH INDIRECT METHOD:

   • Surface temperature (ts);

     FOR MEP PRODUCTION WITH DIRECT METHOD:

   • Precipitation flux (pr);

   • Snowfall flux (prsn);

   • Surface air pressure (ps);

   • Specific humidity on pressure levels (hus);

   • Surface temperature (ts);

   • Near-surface (or 10m) zonal velocity (uas);

   • Near-surface (or 10m) meridional velocity (vas);

   N.B. Precipitation fluxes are expected to have kg m-2 s-1 as u.o.m.

   b. If the option for LEC computation is set, the following variables are needed at the daily resolution or higher
   (required variable name in brackets):

   • Near-surface temperature (tas);
   • Near-surface (or 10m) zonal velocity (uas);
   • Near-surface (or 10m) meridional velocity (vas);
   • Air temperature (on pressure levels) (ta);
   • Horizontal velocity (on pressure levels) (ua);
   • Meridional velocity (on pressure levels) (va);
   • Vertical velocity (on pressure levels) (wap);

   c. The following dimensions are accepted (dimension name in brackets):

   • Longitude (lon);

   • Latitude (lat);

   • Pressure levels (plev);

   • Time (time);

     N.B. The latitude must be S->N (the CDO command 'invertlat' may help adapting data to this requirement). The datasets must be global, i.e. spanning the whole Earth.

     N.B. A calendar time must be defined and the time axis must refer to that. You may use the combination of 'setreftime' and 'settaxis' CDO commands in order to prepare the datasets. In doing so, the time resolution shall be correctly specifiend (see the CDO manual for more information).

     N.B. The grids are expected to be recognised structured lonxlat grids (either regular or gaussian). If this is not the case, you may want to remap to recognised grids, using either remapbil or remapcon CDO commands (see the CDO manual for specific instructions).

   d. In case variable and dimension names do not comply to these requirements you may use the CDO command (for variables): 'chname,namein,nameout filein.nc fileout.nc' and the NCO command (for dimensions): 'ncrename -h -d namein,nameout -v .namein,nameout filename.nc'

   e. Create a folder in the input directory for each model you need to analyse, named after the model.

   f. Provide each field in a different file. The file name must start with the name of the variable.

   g. If the option 'lsm' is set to 'True', a land-sea mask shall be provided as a land area fraction (from 0 to 100) in a separate folder, named as 'ls_mask', at the same level as the folder containing the model outputs for a single model. The land-sea mask is expected to be a NetCDF file whose name format is 'lsmask_<model_name>.nc'. Example:

    model_data/
    model_data/model_name/*.nc
    model_data/ls_mask/lsmask_<model_name>.nc
   

2: The companion script 'namelist.py' is available for the user in order to specify the directory paths. The following options can also be set:

• wat: if set to true, the program will compute the water mass and latent energy budget,
• lec: if set to true, the program will compute the Lorenz Energy Cycle (LEC) averaged on each year;
• entr: if set to true, the program will compute the material entropy production (MEP);
• met: if set to 1, the program will compute the MEP with the indirect method, if set to 2 with the direct method, if set to 3, both methods will be computed and compared with each other;
• evap: if set to 1, evaporation flux is computed from the latent heat fluxes, if set to 2 the field containing the evaporation flux must be provided (this last option shall be preferred, because it gives a more accurate estimate of the water mass budget);

4: Run the tool by typing: 'python thermodyn_diagnostics.py'. Global metrics and additional information is printed out in the log file indicated by the user in the 'namelist.py' script.

Output

The output directory contains the following NetCDF files:

• (output directory):

  • atmos_transp_mean_<model_name>.nc
  • latent_transp_mean_<model_name>.nc
  • ocean_transp_mean_<model_name>.nc
  • total_transp_mean_<model_name>.nc
  • wmb_transp_mean_<model_name>.nc

  contain annual mean meridional sections of heat transports in the atmosphere, oceans, and as a total; latent energy transports and water mass transports;

• (output directory)/<model_name>:

  • <model_name>_atmb.nc
  • (<model_name>_latent.nc; if wat is set to true)
  • <model_name>_surb.nc
  • <model_name>_toab.nc
  • (<model_name>_wmb.nc; is wat is set to true)

  contain annual mean 2D fields of energy budget, latent heat and water mass budgets;

  • <model_name>_barocEff.nc

  contains the evolution of annual mean baroclinic efficiency (Lucarini et al., 2011).

  (if entr is set to true):

  • <model_name>_evap_entr.nc (if met is set to 2 or 3)
  • <model_name>_horizEntropy.nc (if met is set to 1 or 3)
  • <model_name>_pot_drop_entr.nc (if met is set to 2 or 3)
  • <model_name>_rain_entr.nc (if met is set to 2 or 3)
  • <model_name>_sens_entr.nc (if met is set to 2 or 3)
  • <model_name>_snow_entr.nc (if met is set to 2 or 3)
  • <model_name>_snowmelt_entr.nc (if met is set to 2 or 3)
  • <model_name>_verticalEntropy.nc (if met is set to 1 or 3)

  contain the evolution of annual mean components of the material entropy production.

• (plots directory):

  • meridional_transp.png: contains the model inter-comparison of total, atmospheric and oceanic of meridional sections in zonally average meridional heat transports;
  • scatters_summary.png: contains the scatter plots of model intercomparisons of various metrics retrieved in the program;
  • scattes_variability.png: contains scatter plots of model intercomparisons between TOA, atmospheric and surface global mean energy budgets and their inter-annual variability;

• (plots directory)/<model_name>:

  • <model_name>_atmb_timeser.png: the atmospheric budget annual mean global and hemispheric time series;
  • <model_name>_energy_climap.png: the TOA, atmospheric and surface climatological mean fields;
  • <model_name>_heat_transp.png: the meridional sections of total, atmospheric and oceanic meridional heat transports (implied from energy budgets);
  • <model_name>_latent_climap.png: the climatological mean latent heat field;
  • <model_name>_latent_timeser.png: the latent heat annual mean global and hemispheric evolutions;
  • <model_name>_latent_transp.png: the meridional section of annual mean meridional latent heat transport;
  • <model_name>_scatpeak.png: the scatter plots of atmospheric vs. oceanic peak magnitude in both hemispheres;
  • <model_name>_sevap_climap.png: the annual mean field of material entropy production due to evaporation;
  • <model_name>_smelt_climap.png: the annual mean field of material entropy production due to snow melting;
  • _spotp_climap.png: the annual mean field of material entropy production due to potential energy of the droplet;
  • <model_name>_srain_climap.png: the annual mean field of material entropy production due to rainfall precipitation;
  • <model_name>_ssens_climap.png: the annual mean field of material entropy production due to sensible heat fluxes;
  • <model_name>_ssnow_climap.png: the annual mean field of material entropy production due to snowfall precipitation;
  • <model_name>_surb_timeser.png: the surface budget annual mean global and hemispheric time series;
  • <model_name>_sver_climap.png: the annual mean field of vertical material entropy production through the indirect method;
  • <model_name>_toab_timeser.png: the TOA budget annual mean global and hemispheric time series;
  • <model_name>_wmb_climap.png: the climatological mean water mass budget field;
  • <model_name>_wmb_timeser.png: the water mass annual mean global and hemispheric evolutions;
  • <model_name>_wmb_transp.png: the meridional section of annual mean meridional water mass transport;

• (plots directory)/<model_name>/LEC_results:

  • <model_name>__lec_diagram.png: the flux diagram for the annual mean LEC cycle in a specific year;
  • <model_name>__lec_table.txt: the table containing the storage and conversion terms for the annual mean LEC cycle in a specific year;

References

Lembo, V., Lunkeit, F., and Lucarini, V.: TheDiaTo (v1.0) – A new diagnostic tool for water, energy and entropy budgets in climate models, Geosci. Model Dev., 12, 3805–3834, https://doi.org/10.5194/gmd-12-3805-2019, 2019

Versions

2019-04-29: a stand-alone version of TheDiaTo v1.0 is branched from ESMValTool v2.0b repository;

2019-12-09: the water mass budget can be computed from input fields containing evaporation fluxes, if available;