DSS presents a global synoptic set of 6 hourly upper air data reports. These were operationally collected by NCEP. They include radiosondes, pibals and aircraft reports received via the Global Telecommunications System (GTS) and satellite data from the National Environmental Satellite, Data, and Information Service (NESDIS). This data is the primary input to the Global Data Assimilation System (GDAS), which is used to make forecasts and the Global Final Analyses (FNL). It was also a major input for the NCEP/NCAR and ECMWF Reanalysis Projects. NCEP uses Automated Data Processing (ADP), to decode and reformat the GTS reports. The NCEP document Observational Data Processing at NCEP and the NCAR document TN404 An Introduction to Atmospheric and Oceanographic Datasets, (chapter 3) discuss the collection of this data in greater detail.

The ADPUPA data includes upper air station data from land and ship launched radiosondes and pibals. This involves, at 00Z and 12Z, about 650 - 1000 stations, and at 06Z and 18Z (which are mostly pibals), about 150 - 400 stations. The counts have declined in recent years. Data may be available at up to 20 mandatory levels from 1000mb to 1mb, plus a few significant levels. The AIRCFT data includes aircraft flight level reports from commercial, military and reconnaissance sources. There are about 400 every 12 hours in the oldest files, to about 20000 every 6 hours in more recent files. The SIRSOB data includes satellite infrared sounding observation data (discontinued in early 1979) The SATWND data includes satellite winds derived from cloud drift analysis. The AIRCAR data includes data from aircraft takeoff and landings (beginning mid 1991), with between 5000 and 10000 reports every 6 hours. The reports may include pressure, geopotential height, temperature, dewpoint depression, wind direction and speed.

This dataset is in an ASCII character format, known as the NMC Office Note 29 (ON29) format. This is a popular dataset with MM5, WRF and RAMS users - see this.It is updated monthly by converting the daily BUFR files prepared for DSS by NCEP. The BUFR files are kept in DS351.0. The radiosonde and pibal data is free, through the DS353.4 data page. For data prior to 1973 see DS353.0. MORE