Map files

Map files are post-processed data produced from grid files.

Naming Conventions

Map files for each hemisphere

Map files are processed by starting with the combined (or single radar) grid file as an input to map_grd.

From here, additional processsing occurs by adding additional data sources (Heppner-Maynard Boundary, IMF) and statistical convection models (TS18) before having a spherical harmonic fitting performed.

If a map file contains only a small time amount of data, it may be named:

where hhhhh is the hemisphere (north or south).

If a map file is produced with 24-hours of data then the common naming convenction is:

where the hour, minute, and second fields are dropped.


Each record of a map file contains scalar and vector fields.


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) None short Start Day (not padded)
start.hour hr 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) None short End Day (not padded)
end.hour hr short End Hour
end.minute min short End Minute
end.second s short End Seconds
map.major.revision None short Major revision number of mapping routine
map.minor.revision None short Minor revision number of mapping routine
source None string Binary that produced this record
doping.level None short Model doping level
model.wt None short Model weighting
error.wt None short Error weighting
IMF.flag None short IMF availability flag
IMF.delay min short IMF delay
IMF.Bx nT double IMF Bx component
IMF.By nT double IMF By component
IMF.Bz nT double IMF Bz component
IMF.Vx km/s double Solar wind speed, X-component, GSE
IMF.tilt degree double Dipole tilt angle
IMF.Kp None double Kp index number
model.angle None string Statistical clock angle of B
model.level None string Statistical model level
model.tilt None string Calculated tilt angle None string Name of the statical model used (TS18, CS10, RG96, etc.)
hemisphere None short Hemisphere flag (north=1)
noigrf None short Flag for no-IGRF model present
fit.order None short Order of spherical harmonic fit
latmin None float Lower latitude boundary of data
chi.sqr None double True chi-squared error
chi.sqr.dat None double Chi-squared error for data only
rms.err None double RMS error
lon.shft degree float Longitudinal pole shift
lat.shft degree float Latitudinal pole shift
mlt.start hr double MLT at start of record
mlt.end hr double MLT at end of record
mlt.av hr double MLT at middle of record
pot.drop V double Cross polar-cap potential drop
pot.drop.err V double Cross polar-cap potential drop error
pot.max V double Maximum polar-cap potential
pot.max.err V double Maximum polar-cap potential error
pot.min V double Minimum polar-cap potential
pot.min.err V double Minimum polar-cap potentail error


The array components of the map file format are listed below. The map format is a superset of the grid formt so it contains the same arrays.


  • Let the number of radars in a given map record be defined as numstid
  • Let the number of gridded velocity vectors in a given record be defined as numv
  • Let the number of values for the spherical harmonic analysis be defined as numft
  • Let the number of vectors output by the model used be defined as nummd
  • Let the number of the Heppner-Maynard boundary outputs be defined as numbd
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 None [numstid] short Control program ID
noise.mean None [numstid] float Mean noise 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 Maximum velocity threshold
p.min None [numstid] float Minimum power threshold
p.max None [numstid] float Maximum power threshold
w.min m/s [numstid] float Minimum spectral width threshold
w.max m/s [numstid] float Maximum spectral width 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 None [numv] short Channel number
vector.index None [numv] int Grid cell index
vector.vel.median m/s [numv] float Weighted mean velocity magnitude m/s [numv] float Velocity standard deviation
vector.pwr.median dB [numv] float Weighted mean power dB [numv] float Power standard deviation
vector.wdt.median m/s [numv] float Weighted mean spectral width
* m/s [numv] float Standard deviation of spectral width
N None [numft] double L value of the expansion between 0 and Lmax
N+1 None [numft] double M value of the expansion between -L and +L, negative values indicating the sin(M*phi) term
N+2 None [numft] double Value of the coefficient
N+3 None [numft] double Stimate of the 1-sigma error of the coefficient
model.mlat degrees [nummd] float Magnetic Latitudes of the model vectors
model.mlon degrees [nummd] float Magnetic Longitudes of the model vectors
model.kvect degrees [nummd] float Magnetic Azimuths of the model vectors
model.vel.median m/s [nummd] float Velocity medians of the model vectors
boundary.mlat degrees [numbd] float Magnetic Latitudes of the lower latitude boundary
boundary.mlon degrees [numbd] float Magnetic Longitudes of the lower latitude boundary

A map file does not necessarily contain a complete set of all the variables listed above. The processing is dvidied up into stages with variables added to the file as needed. If the statistical model has been calculated the file will contain the arrays model.mlat, model.mlon, model.kvect, and model.vel.median. If the loer boundary ha been found then the file will contain the arrays boundary.mlat and boundary.mlon. If the spherical harmonic analysis has been performed, then the file will contain the arrays N, N+1, N+2, and N+3.

File structure

Map files typically contain up to 24 hours of data. Individual records in a map file contain a record for each integration time period (default 120 seconds) from one or more radars depending on the input grid file.