Measurements of the foreign-broadened continuum of water vapor in the 6.3 (mu)m band at -30 deg C

摘要

The foreign-broadened continuum of water vapor in the v_(2) band (5-7.7 (mu)m, 1300-2000 cm~(-1)) is important for satellite-based retrievals of water vapor in the upper troposphere, where temperatures are below -25 deg C. Continuum coefficients have previously been measured mostly at or above +23 deg C. We present continuum coefficients in the v_(2) band retrieved from measurements made in Antarctica at temperatures near -30 deg C: atmospheric transmission at South Pole Station and atmospheric emission at Dome C. The continuum coefficients derived from these measurements are generally in agreement with the widely used Mlawer, Tobin-Clough, Kneizys, Davies continuum. Differences are at most 30percent, corresponding to a 6percent relative error in retrieved upper-tropospheric humidity.