File Naming Conventions

These rules are generalizations of the naming conventions that were used for GPS/MET which worked well for us:

  • File names are composed of 3 or 4 sections separated by underscores.
    1. A six character id which uniquely identifies the file type.
    2. A file identifier which tells which instance of this file type.
    3. The subtype and version (1b and above)
    4. The format type: pl for perl format, nc for netCDF files, bnx for BINEX files, etc.
  • Files must be identified by year and day of year YYYY.DDD in the name. This is necessary to ensure correct daily archival of files.
  • Files that are associated with downloads from LEO satellites are further identified by 'dump id': YYYY.DDD.SSS.NN where SSS is the LEO constellation id (always '001' if there is only one satellite in the constellation) and NN is the dump number that day. If there is a data downlink (dump) every orbit (say 100 minutes) then there will be around 14 dumps per day. Dump ids are assigned based on the day they ended for midnight crossing dumps.
  • All times are in GPS time.
  • Files that have time intervals not associated with LEO data downloads are idendified as follows: YYYY.DDD.HH.MM.DDDD where HH.MM.DDDD are the hour of day, the minute of the hour and the duration of the file in minutes.
  • All files of level 1b and above have a subtype and version (SSSS.VVVV) attached to them. This is a version number which allows tracking of which program options and which code version are used to generate any given file. The subtype gives information on program options, and the version gives information on code versions. This information applies not only to the most recent data processing step (ie, the program that turned an atmPhs file into an atmPrf file) but to all previous steps as well. So, given the subtype and version of an atmPrf file, one can (with the help of the code version database and CVS) determine the exact code version and options used for all previous processing steps.

Other file conventions

Files for CDAAC exist in many formats including many ASCII Bernese formats, BINEX for GPS data and netCDF for higher level data products.

In order to work with the TACC database interface netCDF files should follow these conventions:

  1. All table fields containing latitudes must have the string 'lat' in the field name. The latitude must be in degrees from -90 (South) to 90 (North).
  2. All table fields containing longitudes must have the string 'lon' in the field name. The longitude must be in degrees from -180 (East) to 180 (West).
  3. All table fields containing dates must be in GPS seconds. The string 'time' must appear in the field name.
  4. Any database fields containing the string 'filename' should contain the name of a generated file available via /pub. These files should if possible be netCDF and abide by certain basic conventions, including:
    • One dimensional variables should have a dimension name and a matching dimension variable. These dimension variables (ie MSL_alt) should be consistent across files to allow statistical comparisons between files.
    • Each variable should have 'long_name' and 'units' attributes to allow display of help text and units.

File Format

  • Level 0
      • Raw data from LEO satellites
        cosLv0 : occ raw data (BlackJack)
        tipLv0 : TIP raw data
        tbbLv0 : TBB raw data
        navMes : 50 bit/s navigation message
      • Fiducial data from GPS ground stations
        igsHrf, igsLrf : Ground GPS fiducial data with high/low sampling rates (RINEX)
      • Atmospheric forecast data
        avnGrb : AVN/GFS 12h forecast data (GRIB)
      • Orbital parameters
        leoTLE : Two-line element data of LEO
  • Level 1a
      • GPS ephemeris, Earth orientation parameters and zenith trop delay
        igsOrb, igsPol, iguOrb, iguPol (sp3/igs )
        iguTrp : IGS zenith tropospheric delay (SINEX )
      • Atmospheric analysis/sounding data
        ncrncp : NCAR/NCEP analysis data (netCDF )
        ecmwfp : ECMWF analysis data (netCDF )
        rsonde : Radiosonde data (netCDF )
        iSonde : Ionosonde data (IIWG )
      • Decoded and reformatted data from level 0
        atmGps : Atm. occ data at the highest resolution (BINEX 0x80)
        ionGps : Ion. occ data at 1-s resolution (BINEX 0x80)
        podGps : 10-s LEO data for LEO orbit computation (BINEX 0x7f)
        avn12h : AVN/GFS 12h forecast data (netCDF)
        f30Gps : Fiducial data at 30-s resolution (BINEX 0x7f)
      • Other intermediates
        dofidT, doleoO, lev1st, qcfile, rnxMet
  • Level 1b
      • POD data, GPS clock, Earth pole offsets and normal equations
        gpsPod : GPS orbit specification file (Bernese STD)
        leoPod, leoOrb : LEO orbit specification files (Bernese STD/sp3 )
        gpsClk : GPS clocks extracted from GPS orbits (Berne CLK)
        brnPol : Earth pole offsets (Bernese ERP )
        fidNeq : Normal equations used in solving for fiducial tropospheric value (Bernese NEQ)
        fidTrp : Zenith tropospheric delay above fiducial sites (Bernese TRP)
      • Excess phase
        atmPhs, ionPhs : Atm./Ion. excess phase (netCDF) high-level
      • Other intermediates
        occTab : Atm./Ion. occ table (Information about occ existing, where/when they occurred) (netCDF )
        atmObj, ionObj : Atm./Ion. occ object file (file names of all files to be processed)
  • Level 2
    atmPrf : Profiles of bending angle, impact parameter, refractivity, dry pressure, dry temperature, MSL altitude of perigee, lon/lat of perigee, azimuth of occ plane, etc. (netCDF) high-level
    wetPrf : Profiles of refractivity, temperature, H2O vapor pressure, pressure level, MSL altitude, lon/lat (netCDF) high-level
    ionPrf : Profiles of electron density, occ TEC below LEO, altitude (netCDF) high-level
    avnPrf, ncpPrf, sonPrf : Temperature, pressure and moisture profiles generated from AVN, NCAR/NCEP, radiosonde data and colocated with occ profiles (netCDF) high-level
    ecmPrf : Temerature, pressure and moisture profiles generated from ECMWF and colocated with occ profiles (netCDF) high-level
    bfrPrf : low resolution atm. profile (BUFR )
    dbdump : database information