Far infrared remote sounding of stratospheric temperature and trace gas distributions

Abstract

The thermal emission spectrum of the Earth's stratosphere in the far infrared exhibits rotational transitions of a large number of trace constituents in addition to the magnetic dipole lines of molecular oxygen. Stratospheric lines that have been identified in the far infrared spectrum include H2O, O3, HNO3, N2O, CO, HCl, HF, HCN and OH. This paper discusses the potential usefulness of far infrared thermal emission measurements for simultaneous retrieval of temperature and constituent distributions. A description of the high-resolution Michelson interferometer currently employed for balloon-borne far infrared stratospheric studies is given, along with a summary of the mode of limbscan observations and an example of an observed spectrum. Numerical results based on synthetic limb radiance data for model atmospheres are presented. Formal inversion techniques with a radiative transfer model based on line-by-line transmittance calculations are employed.