A new dataset, Comprehensive Historical Upper-Air Network (CHUAN), has been developed as a systematic compilation of the different sources in only three standard formats. The first includes the data that come on pressure levels from all platforms except radiosondes, second for the data on geometrical altitude levels, and third with four additional pressure levels for the radiosonde data. The pilot balloon data are given predominantly on geometrical altitude levels above mean sea level, but some observations are given on levels above ground level or on pressure levels. The radiosonde data are given solely on pressure (p) levels whereas the kite, aircraft, and registering balloon data are either on pressure or geometrical altitude levels. CHUAN data have been reformatted into three simple ASCII formats, one each for pressure level and geometrical altitude level data, and one with four additional pressure levels for the radiosonde data.