The COSPAR International Reference Atmosphere (CIRA) provides empirical models of atmospheric temperature and densities from 0 km to 2000 km as recommended by the Committee on Space Research (COSPAR). Since the early sixties different editions of CIRA have been published: CIRA 1961, CIRA 1965, CIRA 1972. The CIRA Working Group meets bi- annually during the COSPAR General Assemblies. In the thermosphere (above about 100 km) CIRA-86 is identical with the MSIS-86 model. For the lower part (0 km to 120 km) the model consists of tables of the monthly mean values of temperature and zonal wind for the latitude range 80 N to 80 S. Two sets of files are provided, one in pressure coordinates, including also the geopotential heights, and one in height coordinates, including also the pressure values. These tables were generated by Fleming et al. (1988) from several global data compilations including ground-based and satellite (Nimbus 5, 6, 7) measurements: Oort (1983), Labitzke et al. (1985). The lower part was merged with MSIS-86 at 120 km altitude. In general, hydrostatic and thermal wind balance is maintained at all levels. The model accurately reproduces most of the characteristic features of the atmosphere, such as the equatorial wind and the general structure of the tropopause, stratopause, and mesopause.

The CIRA software includes the original CIRA-86 data files in binary format as provided by E. Fleming (Nov 1989). A simple drive program was written at NSSDC to facilitate access to the binary data. In addition a corrected version of the CIRA data files as provided by J. Barnett in July 1990 is provided in ASCII format.