GRID files

GRID files are post-processed data produced from FITACF files.

Naming Conventions

Single radar GRID files

Currently the common naming convention for a single radar GRID file is:

YYYYMMDD.HH.mm.ss.<3-letter abbreviation>.grid

Some radars provide separate data files for each channel. In this case, the channel is specified after the 3-letter station ID:

YYYYMMDD.HH.mm.ss.<3-letter abbreviation>.[a-d].grid

See fitacf documentation for more information on this naming convention.

If a GRID file is produced for 24-hours using the -c option in make_grid (see make_grid tutorial) or by combining individual GRID files with combine_grid, then the common naming convention is:

YYYYYMMDD.<3-letter abbreviation>.grid

Combined GRID files for each hemisphere

After GRID files are produced for separate radars, they may then be combined with other radars' GRID files for eventual processing into convection map files. See combine_grid for instructions on how to combine multiple GRID files.

For further Map Potential processing, separate GRID files should be produced for the Northern and Southern Hemispheres. One naming convention for 24-hr GRID files could be:

YYYYMMDD.north.grid
YYYYMMDD.south.grid

Fields

GRID files contain a record that contains scalar and vector fields.

Scalars

The following times refer to the start and end of the integration period.

Field name Units Data Type Description
start.year None short Start Year
start.month None short Start Month number (not padded)
start.day None short Start Day (not padded)
start.hour hrs short Start Hour
start.minute min short Start Minute
start.second s short Start Seconds
end.year None short End Year
end.month None short End Month (not padded)
end.day None short End Day (not padded)
end.hour hrs short End Hour
end.minute min short End Minute
end.second s short End Seconds

Vectors

Note

Let the number of radars in a given GRID record be defined as numstid, and let the number of gridded velocity vectors in a given record be defined as numv.

Field name Units Dimensionality Data Type Description
stid None [numstid] short A list of of numeric station IDs that provided data for the record
channel None [numstid] short A list of channel numbers associated to the station id the record
nvec None [numstid] short Number of velocity vectors for each station
freq kHz [numstid] float Transmitted frequency for each radar
major.revision None [numstid] short Major make_grid version number
minor.revision None [numstid] short Minor make_grid version number
program.id None [numstid] short Control program ID
noise.mean None [numstid] float Mean noise
noise.sd None [numstid] float Noise Standard deviation
gsct None [numstid] short Groundscatter flag
v.min m/s [numstid] float Minimum velocity threshold
v.max m/s [numstid] float Velocity maximum threshold
p.min None [numstid] float Power minimum threshold
p.max None [numstid] float Power maximum threshold
w.min m/s [numstid] float Spectral width minimum threshold
w.max m/s [numstid] float Spectral width maximum threshold
ve.min m/s [numstid] float Velocity error minimum threshold
ve.max m/s [numstid] float Velocity error maximum threshold
vector.mlat degrees [numv] float Magnetic Latitude
vector.mlon degrees [numv] float Magnetic Longitude
vector.kvect degrees [numv] float Magnetic Azimuth
vector.stid None [numv] short Station identifier
vector.channel None [numv] short Channel number
vector.index None [numv] int Grid cell index
vector.vel.median m/s [numv] float Weighted mean velocity magnitude
vector.vel.sd m/s [numv] float Velocity standard deviation
vector.pwr.median dB [numv] float Weighted mean power
vector.pwr.sd dB [numv] float Power standard deviation
vector.wdt.median m/s [numv] float Weighted mean spectral width
*vector.wdt.sd m/s [numv] float Standard deviation of spectral width

File structure

GRID files typically contain up to 24 hours of data. Individual records in a GRID file contain a record for each integration time period (default 120 seconds) from one or more radars.