Case 1: Single observation test with GLOBAL BE

Case 1: Single observation test with GLOBAL BE cindyhg Mon, 07/15/2019 - 14:38

ARW SINGLE OBSERVATION TEST W/ GLOBAL BE

Introduction

This exercise consists of running the GSI analysis with a single pseudo observation at a specified location, to illustrate how that observation influences the analysis. 

Further information on setting up a single observation test is available in section 4.2 of the GSI User's Guide. 

The ARW background field is provided in netcdf format, and the global BE is employed as the background error covariance.

Setting up the Run Script

Setting up the Run Script cindyhg Mon, 07/15/2019 - 14:40

ARW SINGLE OBSERVATION TEST W/ GLOBAL BE

Setting up the Run Script

For this exercise, make a copy of the prepared basic run script from the section Prepare run script for basic cases: 

cp run_gsi_regional.ksh run_gsi_regional.ksh_psot. 

Make the following additional modifications to the script run_gsi_regional.ksh_psot:

  • Set the name/path for the analysis run directory
  • Set up the one observation test option to true
  • if_oneob=Yes
  • Select the background field format
  • bk_core=ARW
  • Select the global background error covariance
  • bkcv_option=GLOBAL

An example of this run script is available from the link run_gsi_regional.ksh

Check the GSI namelist

Users can check the namelist to see how to set up a single observation test. The related namelist options include :

  • oneobtest=.true.
  • Set the location of the pseudo observation: &SINGLEOB_TEST
    maginnov=1.0,magoberr=0.8,oneob_type='t',
    oblat=38.,oblon=279.,obpres=500.,obdattim=${ANAL_TIME},
    obhourset=0.,
    /

An example namelist is available here.

Running the Script

Running the Script cindyhg Mon, 07/15/2019 - 14:40

ARW SINGLE OBSERVATION TEST W/ GLOBAL BE

Running the Script

In this example, GSI is run as a 4-core MPI job. If you named your run script run_gsi_regional.ksh_psot and run on PBS system (Cheyenne), type: 

qsub run_gsi_regional.ksh_psot 

to launch the job. The progress of the job can be monitored by examining the tail of the standard out file in the run directory as set in the variable WORK_ROOT: 

tail stdout

When completed,the contents of this run directory are provided in the following list .