Analysis of far-infrared spectral radiance observations of the water vapor continuum in the Arctic

• Coincident far-infrared spectra measured by two independent radiometers compared.
• TAFTS and AERI-ER instruments show good agreement within measurement range overlap.
• A case study of far-infrared Arctic radiance measurements by the TAFTS instrument.
• Simulated and observed radiances used to test the MT-CKD water vapor continuum model.
• Measured TAFTS radiances show agreement with simulations and previous studies.

The Radiative Heating in Underexplored Bands Campaign (RHUBC) took place in Barrow, Alaska, in February and March 2007. During RHUBC, high resolution far-infrared spectra were measured simultaneously and independently by two different spectrometers – the Imperial College Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) and the Atmospheric Radiation Measurement program (ARM) Atmospheric Emitted Radiance Interferometer – Extended Range (AERI-ER). Co-incidental far-infrared downwelling radiance measurements from the two instruments show good agreement within their overlapping wavenumber measurement range (400–550 cm−1). Radiance measurements taken using the TAFTS instrument are compared to the current Mlawer–Tobin–Clough–Kneizys–Davies (MT-CKD) version 2.5 water vapor continuum parameterization for the spectral range 350–500 cm−1 (20–29 μm). Simulated values agree with the TAFTS observations within uncertainties, enhancing confidence that MT-CKD 2.5 accurately represents the foreign-broadened water vapor continuum in this crucial spectral region.