Far infrared emission spectrum of the stratosphere from balloon altitudes

Abstract

WE present here observations of the far infrared emission spectrum of the stratosphere taken with a balloon-borne interferometer from an altitude of 22 km above Churchill, Manitoba, Canada (latitude 58.7°N, longitude 94° W) in July, 1974. The instrument was part of a composite Atmospheric Environment Service of Canada gondola whose overall aim was the measurement, by several complementary methods, of the concentrations of minor constituents of the atmosphere and the monitoring of their changes with altitude and time during the flight. Many of the minor constituents of particular interest in the current debate on stratospheric pollution (O3, H2O, NO2, N2O, NO, HNO3, HCl, SO2) exhibit pure rotation spectra in the far infrared and are expected to contribute to the stratospheric emission spectrum. O2, a well known and well behaved constituent of the stratosphere emits a series of weak magnetic dipole lines in this wavelength region, with intensities matching those of intrinsically stronger ones from less abundant species, and which can be used for spectral normalisation (see ref. 3).