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

Abstract

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 (400–550cm−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 350–500cm−1 (20–29μm). 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.