The Reader three-hourly observation data are composed of the nearest valid instantaneous observation within 40 minutes of the synoptic reporting times (i.e., 00, 03, 06, 09, 12, 15, 18, and 21). These data are uncorrected for the years 1980-1990, gross error checked for 1991-2000, and quality controlled for 2001 to the present. The file names for the 3-hourly data are constructed using the station's ARGOS identifier, the month, and the year. A file name such as 9061291h.dat would be read as station 8906 (906), December (12), 1991 (91), and contains a two-line header (h) with the extension indicating ASCII format data (.dat). Note that the leading '8' (08 after 2000) is dropped from the ARGOS ID to allow for an 8- character file name. The data are arranged in columns of temperature (degrees C), pressure (mb), wind speed (m/s), wind direction, relative humidity, and vertical temperature difference. Dome Fuji (8904) is an exception to this, where the relative humidity column is instead lower temperature (C).

The vertical temperature difference is measured from 3.0m to 0.5m minus the zero calibration. Missing data are represented as 444.0. All months have 31 days until 2001 when the months have the correct number of days in them. Note that the four column datasets are arranged as above, minus relative humidity and vertical temperature difference. Wind directions listed are the direction the wind is blowing from, from 0 to 360 clockwise (thus 90 degrees is east, 180 is south, and 270 is west).