PCPCombine: SUBTRACT Use Case

met_tools_wrapper/PCPCombine/PCPCombine_subtract.conf

Scientific Objective

Extract a 3 hour precipitation accumulation field by subtracting a 15 hour accumulation field from an 18 hour accumulation field.

Datasets

Forecast: WRF precipitation accumulation fields (18 hour and 15 hour forecast leads)
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: WRF

METplus Components

This use case utilizes the METplus PCPCombine wrapper to search for files to extract the desired accumulation for a given run time using a filename template, forecast lead, and output accumulation. It will a generate a command to run PCPCombine to subtract a field from another field to extract the desired accumulation.

METplus Workflow

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

Valid: 2005-08-07_00Z
Forecast lead: 18 hour

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_subtract.conf

[config]

# Documentation for this use case can be found at
# https://metplus.readthedocs.io/en/latest/generated/met_tool_wrapper/PCPCombine/PCPCombine_subtract.html

# For additional information, please see the METplus Users Guide.
# https://metplus.readthedocs.io/en/latest/Users_Guide

###
# Processes to run
# https://metplus.readthedocs.io/en/latest/Users_Guide/systemconfiguration.html#process-list
###

PROCESS_LIST = PcpCombine


###
# Time Info
# LOOP_BY options are INIT, VALID, RETRO, and REALTIME
# If set to INIT or RETRO:
#   INIT_TIME_FMT, INIT_BEG, INIT_END, and INIT_INCREMENT must also be set
# If set to VALID or REALTIME:
#   VALID_TIME_FMT, VALID_BEG, VALID_END, and VALID_INCREMENT must also be set
# LEAD_SEQ is the list of forecast leads to process
# https://metplus.readthedocs.io/en/latest/Users_Guide/systemconfiguration.html#timing-control
###

LOOP_BY = INIT

INIT_TIME_FMT = %Y%m%d%H
INIT_BEG = 2005080700
INIT_END = 2005080700
INIT_INCREMENT = 1M

LEAD_SEQ = 18H


###
# File I/O
# https://metplus.readthedocs.io/en/latest/Users_Guide/systemconfiguration.html#directory-and-filename-template-info
###

FCST_PCP_COMBINE_RUN = True

FCST_PCP_COMBINE_INPUT_DIR = {INPUT_BASE}/met_test/data/sample_fcst
FCST_PCP_COMBINE_INPUT_TEMPLATE = {init?fmt=%Y%m%d%H}/wrfprs_ruc13_{lead?fmt=%HH}.tm00_G212

FCST_PCP_COMBINE_OUTPUT_DIR = {OUTPUT_BASE}/met_tool_wrapper/PCPCombine/PCPCombine_subtract
FCST_PCP_COMBINE_OUTPUT_TEMPLATE = wrfprs_ruc13_{init?fmt=%Y%m%d%H}_f{lead?fmt=%HH}_A03.nc


###
# PCPCombine Settings
# https://metplus.readthedocs.io/en/latest/Users_Guide/wrappers.html#pcpcombine
###

#LOG_PCP_COMBINE_VERBOSITY = 2

FCST_PCP_COMBINE_METHOD = SUBTRACT

FCST_PCP_COMBINE_MAX_FORECAST = 2d

FCST_IS_PROB = false

FCST_PCP_COMBINE_INPUT_DATATYPE = GRIB

FCST_PCP_COMBINE_OUTPUT_ACCUM = 3H

FCST_PCP_COMBINE_OUTPUT_NAME = APCP_03

FCST_PCP_COMBINE_USE_ZERO_ACCUM = False

MET Configuration

None. PCPCombine does not use configuration files.

Running METplus

This use case can be run two ways:

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

    run_metplus.py -c /path/to/METplus/parm/use_cases/met_tool_wrapper/PCPCombine/PCPCombine_subtract.conf -c /path/to/user_system.conf
    
  2. Modifying the configurations in parm/metplus_config, then passing in PCPCombine_subtract.conf:

    run_metplus.py -c /path/to/METplus/parm/use_cases/met_tool_wrapper/PCPCombine/PCPCombine_subtract.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_subtract (relative to OUTPUT_BASE) and will contain the following files:

  • wrfprs_ruc13_2005080700_f24_A18.nc

Keywords

Note

  • PCPCombineToolUseCase

Navigate to the METplus Quick Search for Use Cases page to discover other similar use cases.

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