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Two-way Coupled Meteorology Chemistry WRF-CMAQ

Author/P.O.C.:, David Wong, Computational Exposure Division, U.S. EPA

Brief Description

The new two-way coupled WRF-CMAQ model which is based on WRF 3.8 and CMAQ 5.2, is an online meteorology-chemistry model that simulates the two-way feedback between meteorology and chemistry. The feedback focuses on the interactions of estimated aerosol mass on incoming shortwave radiation.

Build Instructions

  • Download WRF 3.8 and unzip it (recommend command: tar xfz the_zip_file). At the end of this step, you will see a new directory WRFV3 and rename it to WRFV38.

  • Configure WRF by typing configure. This creates a configure.wrf file.

  • If you have never done WRF configure before, here are some guidelines:

    1. If the configure script does not find the NETCDF path, follow the prompt to enter the explicit NETCDF include path and library path.
    2. Option selection determines by choosing an approriate compiler vendor and hardware description on right most column of the displayed option table and intercept with the third column (dmpar). Example: for INTEL (ifort/icc), selection is 15.
    3. In the compile for nesting section, choose the default value.

  • Download IOAPI_3.1 (or IOAPI 3.2) and install it.

  • Go through regular building CMAQ model process. Make sure bldit.cctm script have:

    set MakeFileOnly line uncomment out

    set build_twoway line uncomment out

  • After running the blidit.cctm script, rename BLD_* as cmaq and move it into WRFV38 directory.

  • Download coupled model tarball from the EPA ftp site: ftp://newftp.epa.gov/exposure/CMAQ/V5_2/WRF-CMAQ_Coupled_Model/ (file name="WRF3.8_CMAQ5.2_TwoWay_Model.tar.gz"). Unzip the tarball and then move the twoway directory inside WRFV38 as well.

  • Go into directory WRFV38 and execute the following command:

    twoway/assemble

    This command will update all necessary files in WRF and CMAQ to create the twoway model. You can find the original files inside twoway/misc/orig directory.

  • Note:

    1. You might need to edit the IOAPI and MPI paths in configure.wrf base on the location of those two libraries on your system.

    2. You can also replace the netCDF link with explicit netCDF path under LIB_EXTERNAL and NETCDFPATH. Copy configure.wrf to configure.wrf.saved. Once you have this done and in the future if you type clean -a, you can restore the configure file by cp configure.wrf.saved configure.wrf without going through configure step again.

    3. In the future, when you bring in a newer version of cmaq, you just need to type:

      twoway/assemble m

      and a Makefile.twoway will be created inside that new cmaq directory.

  • Compile the twoway model by typing compile em_real >& mylog. This might take some time for completion and you can monitor size changes of file, mylog. If compilation is done successfully, you can find main/wrf.exe file.

WRF-CMAQ Input/Output Data and Run Instructions

A test dataset is available from the CMAS Center Software Clearinghouse. After logging in to the CMAS Center, select Download -> Software -> CMAQ and choose version 5.2. Click on "Download Datasets" and then browse to the folder WRF38-CMAQ52_Coupled_Model to download model input and reference output (WRFv3.8_CMAQv5.2_Input.tar.gz, WRFv3.8_CMAQv5.2_Output.tar.gz). Once you unpack the files, you can store them anywhere you want.

A sample run script, twoway_model_run_script, is in the WRFv3.8_CMAQv5.2_TwoWay_Model.tar.gz under the script subdirectory. In order to use this script to run the WRF-CMAQ two-way model, you need to modify two variables: WRF_DIR and INPDIR. In general, the area in between

# ##### begin user define area #####

and

# ##### end user define area #####

can be modified to suit a particular simulation.

The WRF-CMAQ benchmark data provide examples of the files needed to run the model. The general list of inputs required for WRF-CMAQ include,

  • REAL outputs :: wrfbdy, wrflowinp, wrffdda, wrfsfdda, wrfrstrt
  • CMAQ inputs :: emissions, IC, BC, OMI, ocean file

WRF-CMAQ outputs standard WRF (wrfout) and CMAQ output files.

If you have any question, please contact David Wong at wong.david-c@epa.gov

References:

Wong, D. C., Pleim, J., Mathur, R., Binkowski, F., Otte, T., Gilliam, R., Pouliot, G., Xiu, A., Young, J. O., and Kang, D.: WRF-CMAQ two-way coupled system with aerosol feedback: software development and preliminary results, Geosci. Model Dev., 5, 299-312, doi:10.5194/gmd-5-299-2012 , 2012.

For an overview of the 2-way Coupled WRF-CMAQ see: http://www.cmascenter.org/conference/2011/slides/mathur_overview_two-way_2011.pptx

and for more details on the 2-way Coupled WRF-CMAQ system see: http://www.cmascenter.org/conference/2011/slides/wong_wrf-cmaq_two-way_2011.pptx