The following distribution options and limitations apply to data from the Greenland magnetometer array including coastal (DMI) and ice cap (SPRL) stations. Data are available upon request in

• Binary format ("General Data Format" or "GDF" files)
  Each file contains data from all stations in operation during the specified day (in random order);
      mix of ASCII, character array and short integer variables in Big Endian byte ordering
  Time span : always 00-24 UT
  Amplitude resolution : 0.25 nT
  Sampling rate : 20 seconds (20-s mean values)
  Time stamps refer to the beginning of the 20-s intervals
  Quiet levels are stored in the header but not subtracted from the data
  Magnetic field elements : local magnetic north (H), east (E) and vertical (Z)
  This format should only be requested by users who have experience with handling binary data

• ASCII format, rather similar to the World Data Center format ("WDC" files)
  Each file may contain data from one or more stations, depending on the request
  Time span : any integer number of hours in the interval 00-24 UT
       (not across the UT midnight boundary)
  Amplitude resolution : 1 nT
  Sampling rate : 20 seconds (20-s mean values)
  Time stamps refer to the beginning of the 20-s intervals
  Quiet level, if available, is subtracted from the data
  Magnetic field elements : local magnetic north (H), east (E) and vertical (Z)
  This format is obsolete and will no longer be used for distribution of variometer data

• ASCII format according to the IAGA 2000 guidelines ("ASCII Delimited Columns" or "ADC" files)
  Each file contains data from one single station
  Time span : any integer number of hours between 1 (minimum) and 24 (maximum)
  The requested interval may start at any full hour, and its length is not limited by the UT midnight boundary
  Amplitude resolution : 0.25 nT
  Sampling rate : original (20 seconds -- mean values) or decimated (1-, 2- or 5-minute samples)
       (Decimation is automatically preceded by appropriate low pass filtering)
  Time stamps refer to the center of the selected sampling interval
       20-s values : centered on 10, 30, 50 seconds
       1-min values : centered on full minutes
       2-min values : centered on full odd minutes (consistent with SuperDARN standard mode)
       5-min values : centered on integer multiples of 5 minutes
  Quiet level may or may not be subtracted
  Lowpass, highpass, or bandpass Kaiser-Bessel filters with selectable cutoff periods may be applied
  Magnetic field elements : optional
       local magnetic (H,E,Z)
       approximately geographic (X,Y,Z)
       approximately corrected geomagnetic (CGM - H,E,Z).
  The GEO-CGM code (v.2001) provided by NSSDC, Space Physics is used to compute CGM latitude, oval angle and IGRF declination.

• ASCII format according to a modified version of the IAGA 2000 guidelines ("ASCII Free Columns" or "AFC" files)
  Identical to the IAGA2000 format except that the vertical delimiter bars in the data records are replaced by blanks