Coupling GEOS-Chem with RRTMG
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On this page we provide information about the coupling of GEOS-Chem with the RRTMG radiative transfer model (by AER, Inc.).
Overview
The GEOS-Chem model with online radiative transfer calculations (referred to as GCRT) was developed to allow GEOS-Chem users to produce gas and aerosol direct radiative effect (DRE) output for both the longwave and shortwave. This alternative to offline coupling allows better temporal resolution in the RT calculations and provides a consist platform for GEOS-Chem users with the widely used radiative transfer package RRTMG.
Most of the added code is 'transparent', therefore this version of the GEOS-Chem model can still be run with the radiation code switched off. The optical properties are calculated at multiple wavelengths so that the user is no longer restricted to 550nm as default, so there are associated changes regardless of whether the radiative code is invoked. However, these cause negligible slow down (the default model is actually slightly faster than the standard v9-01-03). Compiling with RRTMG=yes requires approximately double the amount of RAM (~15Gb for a 2x2.5 simulation) and takes between 40% and 100% longer depending on the settings used.
This wiki explains the key changes and requirements. If you want to dig deeper into the changes and assumptions made, or are looking for a quick-start guide to running the model, download the GCRT User Guide
GCRT User Groups
| User Group | Personnel | Projects |
|---|---|---|
| Atmospheric Chemistry, Massachusetts Institute of Technology | Colette Heald David Ridley Xuan Wang |
|
| Add yours here |
Obtaining the source code
GCRT was originally added into GEOS-Chem v10-01i, which was tested with 1-month benchmark simulations approved on 30 April 2015 and a 1-year benchmark simulation approved on 01 May 2015. It is included in the GEOS-Chem v10-01 public release.
--Melissa Sulprizio (talk) 22:15, 16 June 2015 (UTC)
The following bug fix for GCRT will be added into GEOS-Chem v11-01a. Interested users should update to this version once it is ready. Contact the GEOS-Chem Support Team for more information.
--Bob Y. (talk) 16:11, 26 June 2015 (UTC)
Authors and collaborators
- David Ridley (Civil and Environmental Engineering, MIT) -- Lead Developer
- Colette Heald (Civil and Environmental Engineering, MIT) -- Principal Investigator
- Steven Barrett (Aeronautics and Astronautics, MIT)
- Karen Cady-Pereira (AER)
- Matthew Alvarado (AER)
Key Changes
- A menu for Radiation exists in geoschem_config.yml. This also includes a wavelength selection for optical depth output that is independent of whether RRTMG is switched on (up to three optical depths can be output in the HISTORY diagnostics.
- A code folder, GeosRad/ is required for the RRTMG code. The module rrtmg_rad_transfer_mod.F90 is the driver code (found in GeosCore/) that interfaces with RRTMG.
- The optics look-up tables are updated, containing multiple wavelengths and separated into files for each species (soot.dat, so4.dat, org.dat, dust.dat, ssa.dat, ssc.dat) that are stored in the run directory. To prevent discrepancies jv_spec.dat no longer contains optical properties for aerosol, Fast-J uses aerosol optics from from the same speciated look-up tables. The new files mean that jv_spec_aod.dat is obsolete and has been removed.
- Several new input files are required. Surface albedo and emissivity climatologies have been generated and must be stored in modis_surf_201210/ within the root data directory (e.g. ExtData/CHEM_INPUTS/). Climatologies of gases (CH4, N2O, CFC-11, CFC-12, CFC-22 and CCl4) must be stored within the root data directory.
- Diagnostics are available providing the change in radiative flux (DRE) for gases and aerosol, LW/SW, top of atmosphere (TOA) and surface, and clear-sky and all-sky conditions. These also include AOD, SSA and asymmetry parameter for each aerosol species at the requested wavelengths.
Running GCRT
The species available for output from the flux calculations are as follows:
| # | Abbreviation | Species |
|---|---|---|
| 0 | BA | Baseline calculation |
| 1 | O3 | Ozone |
| 2 | ME | Methane |
| 3 | SU | Sulfate |
| 4 | NI | Nitrate |
| 5 | AM | Ammonium |
| 6 | BC | Black carbon |
| 7 | OA | Organic aerosol |
| 8 | SS | Sea salt |
| 9 | DU | Mineral dust |
| 10 | PM | All particulate matter |
| 11 | ST | Stratospheric aerosol (UCX simulation only) |
Please note:
- The radiative impacts of gases (ozone and methane) are relatively untested at this stage and should be interpreted with caution.
- If you are using the UCX chemistry mechanism, then you will need to add an extra entry (0 or 1) at the end of the species fluxes line for stratospheric aerosols for a total of 11 possible species.
- For more information please consult the GCRT User Guide (NOTE: Several items in this document may be now obsolete.)
Settings in geoschem_config.yml
For more information about these settings, please see the geoschem_config.yml chapter in our ReadTheDocs documentation.
#============================================================================
# Timesteps settings
#============================================================================
timesteps:
transport_timestep_in_s: 600
chemistry_timestep_in_s: 1200
radiation_timestep_in_s: 10800 # <=== timestep for RRTMG
#============================================================================
# Settings for GEOS-Chem operations
#============================================================================
operations:
.. etc ...
rrtmg_rad_transfer_model:
activate: true
aod_wavelengths_in_nm:
- 550
longwave_fluxes: true
shortwave_fluxes: true
clear_sky_flux: true
all_sky_flux: true
fixed_dyn_heating: false
seasonal_fdh: false
read_dyn_heating: false
co2_ppmv: 390.0
Settings in HEMCO_Config.rc
Several of the inputs to RRTMG are stored in netCDF Format for input via HEMCO. These include:
- Diffuse surface albedoes in visible and near-IR
- Direct surface albedoes in visible and near-IR
- Surface emissivity in 16 different wavelength bands
- Concentrations of CCl4, CFC11, CFC12, CFC22, CH4, N2O from TES in ppb
You will see lines similar to this in the HEMCO_Config.rc file that ships with the RRTMG simulation run directory:
#============================================================================== # --- Inputs for the RRTMG radiative transfer model --- # # NOTE: The 2 x 2.5 albedo fields and emissivity fields will produce # differences at the level of numerical noise when comparing output to # simulations from prior versions (esp. when running at 4 x 5 resolution). # You might see larger differences w/r/t prior verisons for a few grid boxes # along the coastline of Antarctica, where the difference in resolution # and regridding will be more apparent in the sharp transition from ice to # ocean. If this is a problem, you can use the data files at 4x5 resolution # for 4x5 RRTMG simulations. # # ALSO NOTE: The algorithm that HEMCO uses to select each time slice is # likely different than what was implemented when reading the old bpch # data from disk. This can also cause differences when comparing to # prior versions. #============================================================================== (((RRTMG * MODIS_ALBDFNIR $ROOT/RRTMG/v2018-11/modis_surf_albedo.2x25.nc ALBDFNIR 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_ALBDFVIS $ROOT/RRTMG/v2018-11/modis_surf_albedo.2x25.nc ALBDFVIS 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_ALBDRNIR $ROOT/RRTMG/v2018-11/modis_surf_albedo.2x25.nc ALBDRNIR 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_ALBDRVIS $ROOT/RRTMG/v2018-11/modis_surf_albedo.2x25.nc ALBDRVIS 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_01 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band01 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_02 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band02 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_03 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band03 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_04 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band04 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_05 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band05 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_06 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band06 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_07 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band07 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_08 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band08 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_09 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band09 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_10 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band10 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_11 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band11 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_12 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band12 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_13 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band13 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_14 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band14 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_15 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band15 2002/1-12/1-31/0 C xy 1 * - 1 1 * MODIS_EMISSIVITY_16 $ROOT/RRTMG/v2018-11/modis_emissivity.2x25.nc RTEMISS_band16 2002/1-12/1-31/0 C xy 1 * - 1 1 * TES_CLIM_CCL4 $ROOT/RRTMG/v2018-11/species_clim_profiles.2x25.nc CCl4 2000/1/1/0 C xyz ppbv * - 1 1 * TES_CLIM_CFC11 $ROOT/RRTMG/v2018-11/species_clim_profiles.2x25.nc CFC11 2000/1/1/0 C xyz ppbv * - 1 1 * TES_CLIM_CFC12 $ROOT/RRTMG/v2018-11/species_clim_profiles.2x25.nc CFC12 2000/1/1/0 C xyz ppbv * - 1 1 * TES_CLIM_CFC22 $ROOT/RRTMG/v2018-11/species_clim_profiles.2x25.nc CFC22 2000/1/1/0 C xyz ppbv * - 1 1 * TES_CLIM_CH4 $ROOT/RRTMG/v2018-11/species_clim_profiles.2x25.nc CH4 2000/1/1/0 C xyz ppbv * - 1 1 * TES_CLIM_N2O $ROOT/RRTMG/v2018-11/species_clim_profiles.2x25.nc N2O 2000/1/1/0 C xyz ppbv * - 1 1 )))RRTMG
The data files are located in the HEMCO/RRTMG/v2018-11 folder on our Input data portal.
Settings in HISTORY.rc
#==============================================================================
# %%%%% THE RRTMG COLLECTION %%%%%
#
# Outputs for different species from the RRTMG radiative transfer model:
# (See http://wiki.geos-chem.org/Coupling_GEOS-Chem_with_RRTMG)
#
# 0=BA (Baseline ) 1=O3 (Ozone ) 2=ME (Methane )
# 3=SU (Sulfate ) 4=NI (Nitrate ) 5=AM (Ammonium )
# 6=BC (Black carbon) 7=OA (Organic aerosol) 8=SS (Sea Salt )
# 9=DU (Mineral dust) 10=PM (All part. matter) 12=ST (Strat aer., UCX only)
#
# NOTES:
# (1) Only request diagnostics you need to reduce the overall run time.
# (2) The ?RRTMG? wildcard includes all output except ST (strat aerosols).
# However, if ST is included explicitly for one diagnostic then it
# will be included for all others that use the wildcard.
# (3) Only enable ST if running with UCX.
# (4) Optics diagnostics have a reduced set of output species (no BASE, O3, ME)
#==============================================================================
RRTMG.template: '%y4%m2%d2_%h2%n2z.nc4',
RRTMG.frequency: 00000000 010000
RRTMG.duration: 00000000 010000
RRTMG.mode: 'time-averaged'
RRTMG.fields: 'RadClrSkyLWSurf_BASE ',
'RadClrSkyLWSurf_O3 ',
'RadClrSkyLWSurf_ME ',
'RadClrSkyLWSurf_SU ',
'RadClrSkyLWSurf_NI ',
'RadClrSkyLWSurf_AM ',
'RadClrSkyLWSurf_BC ',
'RadClrSkyLWSurf_OA ',
'RadClrSkyLWSurf_SS ',
'RadClrSkyLWSurf_DU ',
'RadClrSkyLWSurf_PM ',
#'RadClrSkyLWSurf_ST ',
'RadAllSkyLWSurf_?RRTMG?',
'RadClrSkySWSurf_?RRTMG?',
'RadAllSkySWSurf_?RRTMG?',
'RadClrSkyLWTOA_?RRTMG? ',
'RadAllSkyLWTOA_?RRTMG? ',
'RadClrSkySWTOA_?RRTMG? ',
'RadAllSkySWTOA_?RRTMG? ',
'RadAODWL1_SU ',
'RadAODWL1_NI ',
'RadAODWL1_AM ',
'RadAODWL1_BC ',
'RadAODWL1_OA ',
'RadAODWL1_SS ',
'RadAODWL1_DU ',
'RadAODWL1_PM ',
#'RadAODWL1_ST ',
'RadSSAWL1_SU ',
'RadSSAWL1_NI ',
'RadSSAWL1_AM ',
'RadSSAWL1_BC ',
'RadSSAWL1_OA ',
'RadSSAWL1_SS ',
'RadSSAWL1_DU ',
'RadSSAWL1_PM ',
#'RadSSAWL1_ST ',
'RadAsymWL1_SU ',
'RadAsymWL1_NI ',
'RadAsymWL1_AM ',
'RadAsymWL1_BC ',
'RadAsymWL1_OA ',
'RadAsymWL1_SS ',
'RadAsymWL1_DU ',
'RadAsymWL1_PM ',
#'RadAsymWL1_ST ',
::
References
- Heald, C.L., D.A. Ridley, J.H. Kroll, S.R.H. Barrett, K.E. Cady-Pereira, M.J. Alvarado, C.D. Holmes, Beyond Direct Radiative Forcing: The Case for Characterizing the Direct Radiative Effect of Aerosols, Atmos. Chem. Phys., 14, 5513-5527, doi:10.5194/acp-14-5513-2014, 2014. (Article)