To obtain the continuum in the 6.3-micron band and the rotation band, transmission was measured through horizontal atmospheric paths of up to 1000m using a Fourier transform infrared (FTIR) transmissometer during two summer seasons at South Pole Station. Downwelling radiance was also measured using an atmospheric emitted radiance interferometer (AERI) during two summer seasons and one winter season. The AERI measurements cover the spectral range 420-3000 cm-1; the transmission measurements cover 400-5600 cm-1. The water-vapor density along the horizontal path was measured by frostpoint hygrometers. The vertical profiles of temperature and water vapor were measured by radiosondes launched daily, as well as by special-purpose radiosondes and frostpoint hygrometers flown on a tethered balloon or kite.
Preliminary results suggest that the continuum at -30 C in the shoulder of the 6.3-micron band (1400-1475 cm-1) is lower than the room-temperature continuum, whereas in the band center (1575-1675 cm-1) it is higher than the room-temperature continuum.