Infrared spectrometer for ground-based profiling of atmospheric temperature and humidity

摘要

Abstract: We describe an infrared spectrometer system designed for passive, ground-based remote profiling of atmospheric temperature and humidity. This instrument will be useful in atmospheric science, climate, and global change studies. We plan eventually to demonstrate its potential for unattended remote sensing. If successful, the infrared instrument could become a component of an integrated sounding system being designed for next-generation meteorological observations. At the heart of the infrared instrument is a rugged Michelson interferometer which views thermal atmospheric emission between 550 cm$+$MIN@1$/ and 2000 cm$+$MIN@1$/ (5.0 - 18.2 $mu@m), with 1-cm$+$MIN@1$/ spectral resolution. Calculated weighting functions suggest that we should be able to profile temperature with about 200-m vertical resolution, and humidity with about 500-m vertical resolution, in the lower 2 kilometers of the atmosphere. In order to retrieve accurate profiles, absolute radiometric calibration will be necessary. We have constructed two high-emissivity inner-cone cavities which the interferometer will view between atmospheric measurements in order to establish this calibration. We show measured spectra of a clear atmosphere and of cirrus clouds and point out features of these spectra which will be useful in atmospheric profiling.!