Far-Infrared Fourier-Transform Spectroscopy of the Stratosphere

Fourier-transform spectroscopy of the thermal emission spectrum of the Earth’s stratosphere is a technique of growing importance in the study of ozone-layer chemistry. The far-infrared part of this thermal spectrum, here roughly 7-700 cm-1, includes detectable transitions of many species which are key indicators of the degree to which catalytic reactions of chlorine and bromine compounds are able to destroy ozone. A unique advantage of measuring thermal emission is that the instrument can examine the stratosphere at night as easily as it does the day. It is this combination of circumstances, namely the ability to measure species such as OH and HO2, and the ability to measure throughout the day-night cycle, which has made the far-infrared Fourier-transform spectrometer (FTS) a valuable asset in the study of the stratospheric ozone layer.