INSTRUCTIONS / NAMELIST / FILES / REFERENCES / BUGS / PLANS /

PROGRAM create_real_obs

Contact: Hui Liu
Reviewers:  
Revision: $Revision: 1.1 $
Release Name: $Name: $
Change Date: $Date: 2006/05/30 17:25:38 $
Change history: see CVS log

OVERVIEW

Translating NCEP BUFR files into DART obs_seq.out files (input file to filter) is a 2 stage process. The first stage uses NCEP software to translate the BUFR file into an "intermediate" text file. This is described in prep_bufr. The second step is to translate the intermediate files into an obs_seq.out files, which is done by create_real_obs, as described in this document.

This program provides a number of options to select several observation types (radiosonde, aircraft, and satellite data, etc.) and the DART observation variables (U, V, T, Q, Ps) which are specified in its optional namelist interface &ncepobs_nml which may be read from file input.nml.




OTHER MODULES USED

types_mod
obs_sequence_mod
real_obs_mod
utilities_mod



INSTRUCTIONS

The selection of any combinations of the specific observation fields (T, Q, U/V, and surface pressure) and types (radiosonde, aircraft reports, or satellite wind, etc.) is made in the namelist &ncepobs_nml. All the available combinations of fields X types (i.e. ADPUPA and obs_U) will be written to the obs_seq file. (You will be able to select which of those to use during an assimilation in another namelist (assimilate_these_obs, in &obs_kind_nml), so be sure to include all the fields and types you might want.) You should change Obsbase to the pathname of the decoded PREPBUFR text data files. Be sure that daily_file is set to the value you want.

&ncepobs_nml
  year = 2003, 
  month = 1,
  day = 1,
  tot_days = 31,
  max_num = 700000,
  ObsBase = '.../$YOUR_DART/DART/prep_bufr/work/temp_obs.'
  select_obs  = 1,
  ADPUPA = .true., 
  AIRCAR = .false.,  
  AIRCFT = .true., 
  SATEMP = .false., 
  SFCSHP = .false.,
  ADPSFC = .false.,  
  SATWND = .true., 
  obs_U  = .true., 
  obs_V  = .true.,
  obs_T  = .true.,
  obs_PS = .false.,
  obs_QV = .false.,
  daily_file = .true./

&obs_sequence_nml
  write_binary_obs_sequence = .true.  /
This will produce daily observation sequence files for the period of January 2003, which have the selected observation types and fields; T, U, and V from radiosondes (ADPUPA) and aircraft (AIRCFT). No surface pressure or specific humidity would appear in the obs_seq files, nor observations from ACARS, satellites, and surface stations. The output files look like "obs_seq200301dd", with dd = 1,...,31.


NAMELIST

We adhere to the F90 standard of starting a namelist with an ampersand '&' and terminating with a slash '/'.

namelist / ncepobs_nml /  &
year, month, day, tot_days, max_num, select_obs, ObsBase, 
      ADPUPA, AIRCAR, AIRCFT, SATEMP, SFCSHP, ADPSFC, SATWND, 
      obs_U, obs_V, obs_T, obs_PS, obs_QV

Discussion

This namelist is read in a file called input.nml

Contents Type Description
year, month, day integer Beginning day of the preferred observation period.
tot_days integer Total days of the preferred observation period.
max_num integer Maximum observation number for the current one day files. Default is 800000.
select_obs integer Controls whether to select a subset of observations from the NCEP BUFR decoded daily ascii files.
0 = All observations are selected. Default.
1 = Select observations using the logical parameters below.
daily_file logical Controls timespan of observations in each obs_seq file:
  • true = 24 hour spans (3:01Z to 3:00Z of the next day). Filenames have the form obs_seqYYYYMMDD. Default.
  • false = 12 hour spans (3:01Z to 15:00Z and 15:01Z to 3:00Z of the next day. Such files have HH = 12 or 24 appended to their names.
ObsBase character(len=129) Path that contains the decoded NCEP BUFR daily observation files. Must end with a '/temp_obs.'
ADPUPA logical Select the NCEP type ADPUPA observations which includes land and ship launched radiosondes and pibals as well as a few profile dropsonde. This involves, at 00Z and 12Z, about 650 - 1000 stations, and at 06Z and 18Z (which are mostly pibals), about 150 - 400 stations. Default is .false.
AIRCFT logical Select the NCEP type AIRCFT observations, which includes commercial, some military and reconnaissance reports. They are flight level reports. Default is .false.
AIRCAR logical Select the NCEP type AIRCAR observations, which includes data from aircraft takeoff and landings. Sometimes referred to as ACARS obs. Default is .false.
SATEMP logical Select the NCEP type SATEMP observations, which includes NESDIS ATOVS virtual temperature soundings. Default is .false.
SFCSHP logical Select the NCEP type SFCSHP observations, which includes surface marine (ship, buoy, c-man) reports. Default is .false.
ADPSFC logical Select the NCEP type ADPSFC observations, which includes surface land synoptic station reports. Default is .false.
SATWND logical Select the NCEP type SATWND observations, which includes winds derived from satellite cloud drift analysis. Default is .false.
obs_U logical Select u-component of wind observation. Default is .false.
obs_V logical Select v-component of wind observation. Default is .false.
obs_T logical Select temperature observation. Default is .false.
obs_PS logical Select surface pressure observation. Default is .false.
obs_QV logical Select specific humidity observation. Default is .false.



FILES




REFERENCES

.../DART/ncep_obs/prep_bufr/docs/* (NCEP text files describing the BUFR files)


KNOWN BUGS




FUTURE PLANS

Further development to get observations directly from original
(undecoded) NCEP BUFR files.