MERRA2_UFS_ICS

Regrids the MERRA2 Reanalysis to the UFS weather model grid for initial conditions using the ESMF bilinear regridding method via the xESMF python module.

Requirements

This requires a python 3 environment. You can create your own or use the merra2ics.yml file to recreate the environment.

Required Python Modules

• xarray
• scipy
• numpy
• argparse
• xesmf
• fv3grid - https://github.com/noaa-oar-arl/fv3grid

Required files

This does require the grid description file for UFS. It also requires the MERRA2_400.inst3_3d_aer files from the MERRA2 ReAnalysis. These are available through this website: https://goldsmr5.gesdisc.eosdis.nasa.gov/data/MERRA2/M2I3NVAER.5.12.4/${yyyy}/${mm}/

Installation

The easiest way is to create a new conda environment. You can use the merra2ics.yml file included with this repository to create a new environment.

conda env create --file merra2ics.yml
conda activate merra2ics
pip install git+https://github.com/noaa-oar-arl/fv3grid

or create your own environment like so

conda create -n merra2ics xarray xesmf scipy numpy 

To Use

Retrieve MERRA2 data from HPSS

We have many dates available for P7.1 and P8b already available on HPSS. You can retrieve them like so

htar -xvf /NCEPDEV/emc-naqfc/5year/Barry.Baker/MERRA2_INST_3D_AERO/MERRA2_400.inst_3d_aero_Nv.${yyyy}.nc4 MERRA2_400.inst3_3d_aer_Nv.${yyyymmdd}.nc4

merra2_download.sh

If the data isn't archived on HPSS you can use the merra2_download.sh script to download the data directly from the NASA servers

Example:

./merra2_download.sh 20191201

This will download the required file for December 1st 2019

Process Single Day

first copy merra2 data into the directory. If it is already archived on HPSS you can just download it from there using the following command:

htar -xvf /NCEPDEV/emc-naqfc/5year/Barry.Baker/MERRA2_INST_3D_AERO/MERRA2_400.inst_3d_aero_Nv.${yyyy}.nc4 MERRA2_400.inst3_3d_aer_Nv.${yyyymmdd}.nc4

Then you can execute the python file for all tiles like so:

for i in {1..6}; do 
    ./merra2_to_fv3_cubesphere.py -m MERRA2_400.inst3_3d_aer_Nv.${yyyymmdd}.nc4 -c gfs_ctrl.nc -t gfs_data.tile${i}.nc -r C384
done

Process multiple dayas

To process all tiles for a given day in a more scripted way you can use the add_merra2_day.sh script. add_merra2_day.sh will retrieve the data from HPSS as well as copy the python file to the working directory.