These NCEP ADP operational global synoptic upper air data reports
were collected from the GTS during time slots centered on the
6-hourly analysis times of their global and regional models. Five
types of data were collected, and all types include data for various
levels, such as "significant level" and flight level. The reports
may include pressure, geopotential height, temperature, dew point
depression, wind direction and speed.
The five types are: 1) radiosondes and pibals launched from land
stations and ships (includes 20 mandatory levels from 1000 millibars
to 1 millibar), 2) aircraft flight level reports from commercial,
military and reconnaissance sources, 3) satellite infrared sounding
observations, 4) satellite winds derived from cloud drift analysis,
and 5) data from aircraft takeoffs and landings.