ECHKEVO

Introduction

This page describes how to activate CHKEVO for diagnosing forecast model spin-up of pressure. This diagnostic is available in trunk from r16488. Yann Michel (MF) kindly suggested some of the changes required. The diagnostics are generated as part of a forecast model run up to 3 h or 6 h. A known problem is that the method fails when the first lateral boundary conditions are read by the model. The suggestion is to use BDINT=3 and forecast length 3 h. FULL-POS should also be deactivated in config_exp.h.

Preparations

It is assumed you already have a well defined experiment called your_exp. The following instructions are valid for a 3h diagnostic forecast.

NAMCHK namelist

• Enable CHKEVO in the namelist (in the %arome entries):

  cd $HOME/hm_home/your_exp
  ~hlam/Harmonie co nam/harmonie_namelists.pm

• Edit NAMCHK:

  NAMCHK=>{
  'LECHKEVO' => '.TRUE.,',
  'LECHKTND' => '.TRUE.,',
  'LECHKPS' => '.TRUE.,',
  },

ecf/config_exp.h

• Edit your ecf/config_exp.h as follows:

  POSTP="none"                          # Postprocessing by Fullpos (inline|offline|none).
  BDINT=3
  HH_LIST="00-21:3"                     # Which cycles to run, replaces FCINT
  LL_LIST="3"                           # Forecast lengths for the cycles [h], replaces LL, LLMAIN

• Alternatively for a 6 h diagnostic forecast:

  POSTP="none"                          # Postprocessing by Fullpos (inline|offline|none).
  BDINT=6
  HH_LIST="00-18:6"                     # Which cycles to run, replaces FCINT
  LL_LIST="6"                           # Forecast lengths for the cycles [h], replaces LL, LLMAIN

Results

After running the forecast with CHKEVO activated the statistics of surface pressure tendencies are written to NODE.001_01 log file. This log file is included in the HM_Date_YYYYMMDDHH.html log file (written to $SCRATCH/hm_home/your_exp/archive/log on ECMWF). The results can be obtained by grepping the log file as follows:

grep "^ CHKEVO : " HM_Date_2013041118.html | tail -n +2

This gives the RMS and AVG of pressure tendency for each time step. (The first line is removed as the reading of the start file produces zeros):

 CHKEVO :   2.5683273661035013       0.42575646791552352     
 CHKEVO :   2.5432078820872874       0.36700119757663685     
 CHKEVO :   1.4402533781888094       0.23533175032737094     
 CHKEVO :   1.3677546254375832       0.22965677860570116     
 CHKEVO :   1.1506125378848564       0.20575065246468008     
 CHKEVO :  0.98597708942270756       0.19299583141063531
.....

• The first column contains the string CHKEVO :
• Second column contains the RMS of dps/dt averaged over the domain.
• Second column contains the AVG of dps/dt averaged over the domain.

The RMS of dps/dt alone can be extracted with:

grep "^ CHKEVO : " HM_Date_2013041118.html | tail -n +2 | awk '{print $3}'