5.1.14.5. PCPCombine: Python Embedding Use Case

met_tool_wrapper/PCPCombine/PCPCombine_python_embedding.conf

Scientific Objective

Build a 2 hour precipitation accumulation field from 30 minute IMERG data.

Datasets

Forecast: IMERG HDF5 30 minute precipitation accumulation

Location: All of the input data required for this use case can be found in the met_test sample data tarball. Click here to the METplus releases page and download sample data for the appropriate release: https://github.com/dtcenter/METplus/releases

This tarball should be unpacked into the directory that you will set the value of INPUT_BASE. See Running METplus section for more information.

Data Source: IMERG

External Dependencies

You will need to use a version of Python 3.6+ that has the following packages installed:

* h5-py
* numpy

If the version of Python used to compile MET did not have these libraries at the time of compilation, you will need to add these packages or create a new Python environment with these packages.

If this it the case, you will need to set the MET_PYTHON_EXE environment variable to the path of the version of Python you want to use. If you want this version of Python to only apply to this use case, set it in the [user_env_vars] section of a METplus configuration file.:

[user_env_vars] MET_PYTHON_EXE = /path/to/python/with/h5-py/and/numpy/packages/bin/python

METplus Components

This use case utilizes the METplus PCPCombine wrapper to run a Python script to read input data to build the desired accumulation for a given run time using a filename template and a list of available input accumulations. If enough files meeting the criteria are found to build the output accumulation, it will generate a command to run PCPCombine to combine the data.

METplus Workflow

PCPCombine is the only tool called in this example. It processes the following run times:

Valid: 2018-01-02_13:30Z

METplus Configuration

METplus first loads all of the configuration files found in parm/metplus_config, then it loads any configuration files passed to METplus via the command line with the -c option, i.e. -c parm/use_cases/met_tool_wrapper/PCPCombine/PCPCombine_python_embedding.conf

[config]
# time looping - options are INIT, VALID, RETRO, and REALTIME
LOOP_BY = VALID

# Format of VALID_BEG and VALID_END
VALID_TIME_FMT = %Y%m%d%H%M

# Start time for METplus run
VALID_BEG=201801021300

# End time for METplus run
VALID_END=201801021300

# Increment between METplus runs in seconds. Must be >= 60
VALID_INCREMENT=43200

# List of forecast leads to process
LEAD_SEQ = 0

# Options are times, processes
# times = run all items in the PROCESS_LIST for a single initialization
# time, then repeat until all times have been evaluated.
# processes = run each item in the PROCESS_LIST for all times
#   specified, then repeat for the next item in the PROCESS_LIST.
LOOP_ORDER = times

# List of applications to run
PROCESS_LIST = PCPCombine

# verbosity of PCPCombine MET output
#LOG_PCP_COMBINE_VERBOSITY = 2

# run PCPCombine on observation data
OBS_PCP_COMBINE_RUN = True

# method to run PCPCombine. Options are ADD, SUM, SUBTRACT, and DERIVE
OBS_PCP_COMBINE_METHOD = ADD

# List of variables to compare
OBS_VAR1_NAME = APCP
OBS_VAR1_LEVELS = A06

# Name to identify observation data in output
OBTYPE = IMERG

# File format. Options are GRIB, NETCDF, or GEMPAK
OBS_PCP_COMBINE_INPUT_DATATYPE = PYTHON_NUMPY

OBS_PCP_COMBINE_INPUT_ACCUMS = 6
OBS_PCP_COMBINE_INPUT_NAMES = {PARM_BASE}/use_cases/met_tool_wrapper/PCPCombine/sum_IMERG_V06_HDF5.py {OBS_PCP_COMBINE_INPUT_DIR} IRprecipitation {valid?fmt=%Y%m%d%H} 02

[dir]
OBS_PCP_COMBINE_INPUT_DIR = {INPUT_BASE}/met_test/new/imerg
OBS_PCP_COMBINE_OUTPUT_DIR = {OUTPUT_BASE}/met_tool_wrapper/PCPCombine/PCPCombine_combine_py_embed

[filename_templates]
# format of filenames

OBS_PCP_COMBINE_INPUT_TEMPLATE = PYTHON_NUMPY
OBS_PCP_COMBINE_OUTPUT_TEMPLATE = IMERG.{valid?fmt=%Y%m%d_%H%M}_A{level?fmt=%2H}h

[user_env_vars]
# uncomment and change this to the path of a version of python that has the h5py package installed
#MET_PYTHON_EXE = /path/to/python/with/h5-py/and/numpy/packages/bin/python

MET Configuration

None. PCPCombine does not use configuration files.

Running METplus

This use case can be run two ways:

1. Passing in PCPCombine_python_embedding.conf then a user-specific system configuration file:

   run_metplus.py -c /path/to/METplus/parm/use_cases/met_tool_wrapper/PCPCombine/PCPCombine_python_embedding.conf -c /path/to/user_system.conf
   

2. Modifying the configurations in parm/metplus_config, then passing in PCPCombine_python_embedding.conf:

   run_metplus.py -c /path/to/METplus/parm/use_cases/met_tool_wrapper/PCPCombine/PCPCombine_python_embedding.conf
   

The former method is recommended. Whether you add them to a user-specific configuration file or modify the metplus_config files, the following variables must be set correctly:

• INPUT_BASE - Path to directory where sample data tarballs are unpacked (See Datasets section to obtain tarballs). This is not required to run METplus, but it is required to run the examples in parm/use_cases

• OUTPUT_BASE - Path where METplus output will be written. This must be in a location where you have write permissions

• MET_INSTALL_DIR - Path to location where MET is installed locally

Example User Configuration File:

[dir]
INPUT_BASE = /path/to/sample/input/data
OUTPUT_BASE = /path/to/output/dir
MET_INSTALL_DIR = /path/to/met-X.Y

NOTE: All of these items must be found under the [dir] section.

Expected Output

A successful run will output the following both to the screen and to the logfile:

INFO: METplus has successfully finished running.

Refer to the value set for OUTPUT_BASE to find where the output data was generated. Output for this use case will be found in met_tool_wrapper/PCPCombine/PCPCombine_py_embed (relative to OUTPUT_BASE) and will contain the following files:

• .

Keywords

Note

PCPCombineToolUseCase, PythonEmbeddingFileUseCase, MET_PYTHON_EXEUseCase

sphinx_gallery_thumbnail_path = ‘_static/met_tool_wrapper-PCPCombine.png’