Validation of H_2O continuum absorption models in the wave number range 180–600 cm^−1 with atmospheric emitted spectral radiance measured at the Antarctica Dome-C site

This work presents the results concerning the analysis of a set of atmospheric emitted (down welling) spectral radiance observations in the spectral range 180 to 1100 cm−1 acquired at the Dome-C site in Antarctica during an extensive field campaign in 2011–2012. The work has been mainly focused on retrieving and validating the coefficients of the foreign contribution to the water vapour continuum absorption, within a spectral range overlapping the water vapour rotational band. Retrievals have been performed by using a simultaneous physical retrieval procedure for atmospheric and spectroscopic parameters. Both day (summer) and night (winter) spectra have been used in our analysis. This new set of observations in the far infrared range has allowed us to extend validation and verification of state-of-art water vapour continuum absorption models down to 180 cm−1. Results show that discrepancies between measurements and models are less than 10% in the interval 350–590 cm−1, while they are slightly larger at wave numbers below 350 cm−1. On overall, our study shows a good consistency between observations and state-of-art models and provides evidence toward needing to adjust absorptive line strengths. Finally, it has been found that there is a good agreement between the coefficients retrieved using either summer or winter spectra, which are acquired in far different meteorological conditions.