GTSPP Observations

Overview

GTSPP (Global Temperature-Salinity Profile Program) data measures vertical profiles of ocean temperature and salinity. The GTPSS home page has detailed information about the repository, observations, and datasets. The programs in this directory convert from the netcdf files found in the repository into DART observation sequence (obs_seq) file format.

Data sources

Data from the GTSPP can be downloaded interactively from the GTSPP data server. It is delivered in netCDF file format, one vertical profile per netCDF file.

Currently each vertical profile is stored in a separate file, so converting a months’s worth of observations involves downloading many individual files. The converter program can take a list of input files, so it is easy to collect a month of observations together into a single output file with one execution of the converter program.

The units in the source file are degrees C for temperature, g/kg for salinity, and so far we have not found any error information (not quality control, but observation instrument error values). There is probably instrument source information encoded in these files, but so far we don’t have the key. The quality control values are read and only those with a QC of 1 are retained.

Note

The GTSPP data is in PSU, the dart observation converter gtspp_to_obs converts the observations to MSU.

PSU = g/kg

MSU = PSU/1000 = kg/kg

Programs

The data is distributed in netCDF file format. DART requires all observations to be in a proprietary format often called DART “obs_seq” format. The files in this directory, a combination of C shell scripts and a Fortran source executable, do this data conversion.

Namelist

This namelist is read from the file input.nml. Namelists start with an ampersand ‘&’ and terminate with a slash ‘/’. Character strings that contain a ‘/’ must be enclosed in quotes to prevent them from prematurely terminating the namelist.

&gtspp_to_obs_nml
   gtspp_netcdf_file     = '1234567.nc'
   gtspp_netcdf_filelist = 'gtspp_to_obs_filelist'
   gtspp_out_file        = 'obs_seq.gtspp'
   avg_obs_per_file      = 500
   debug                 = .false.
/

Item	Type	Description
gtspp_netcdf_file	character(len=128)	The input filename when converting a single profile. Only one of the two file or filelist items can have a valid value, so to use the single filename set the list name ‘gtspp_netcdf_filelist’ to the empty string (’ ‘).
gtspp_netcdf_filelist	character(len=128)	To convert a series of profiles in a single execution create a text file which contains each input file, in ascii, one filename per line. Set this item to the name of that file, and set ‘gtspp_netcdf_file’ to the empty string (’ ‘).
gtspp_out_file	character(len=128)	The output file to be created. To be compatible with earlier versions of this program, if this file already exists it will be read in and the new data will be inserted into that file.
avg_obs_per_file	integer	The code needs an upper limit on the number of observations generated by this program. It can be larger than the actual number of observations converted. The total number of obs is computed by multiplying this number by the number of input files. If you get an error because there is no more room to add observations to the output file, increase this number.
debug	logical	If true, output more debugging messages.

Modules used

types_mod
time_manager_mod
utilities_mod
location_mod
obs_sequence_mod
obs_def_mod
obs_def_ocean_mod
obs_kind_mod
netcdf

Known Bugs

Does not have correct code for setting observation error variance yet. Also, not sure if the incoming data qc is strict enough.