Tuesday, 11 January 2005
Surface-based Infrared Interferometers – versatile sensors for the IPY
Calibrated Fourier-Transform Infrared (FTIR) spectroradiometers have been used successfully in Polar Regions for several years in several settings, including ship-based expeditions into the Arctic and on a tower over the icecap in Antarctica. In addition the Atmospheric Radiation Measurement Program (ARM) has deployed an Atmospheric Emitted Radiance Interferometer (AERI) as the North Slope of Alaska site for several years. The ship-based measurements have been made using Marine-AERIs and the Antarctic data using a Polar-AERI (see poster by V. Walden et al). M-AERIs have been deployed on several icebreaking research vessels (Polar Sea, Polar Star, Pierre Radisson, Amundsen and Aurora Australis) in both the Arctic and Antarctic. The M-AERI measurements are of the spectra of atmospheric and surface emitted infrared radiation in the range of wavelengths from ~3 to ~18µm (3020 to 520 cm-1) with a resolution of ~0.5 cm-1. These have been analyzed to retrieve skin surface temperatures, spectral emissivity of the surface, near surface air temperatures, and profiles of atmospheric temperature and humidity to a height of about 3km above the ship. In other experiments at lower latitudes, the M-AERI spectra of atmospheric emission have been analyses to determine the infrared radiative forcing of aerosols. The use of ship-based remote sensing in the Arctic has many advantages, especially when the ice cover is breaking up and installation of in situ sensors is impractical. The measurements can be conducted over long periods without special considerations for dedicated deployments of platforms (e.g. Ice-Raids or Ice Camps). Another important application of FTIR spectra and the derived geophysical variables is in the refinement of algorithms used with satellite measurements and validating the retrieved variables. FTIRs with proven track-records on the Polar environments can make important contributions to IPY projects.
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