Design and characterization of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B2)

MIPAS-B2 is a balloon-borne limb-emission sounder for atmospheric research. The heart of the instrument is a Fourier spectrometer that covers the mid-infrared spectral range (4-14 microns) and operates at cryogenic temperatures. Essential for this application is the sophisticated line-of-sight stabilization system, which is based on an inertial navigation system and is supplemented with an additional star reference system. The major scientific benefit of the instrument is the simultaneous detection of complete trace gas families in the stratosphere without restrictions concerning the time of day and viewing directions. The specifications, the design considerations, the actual realization of the instrument, and the results of characterization measurements that have been performed are described.

Fourier transform measurement of self-, N(2)-, and O(2)-broadening of N(2)O lines: temperature dependence of linewidths

The high-resolution FT interferometer of the Laboratoire d'Infrarouge at Orsay has been used to investigate the broadening of N(2)O lines in the 4- and 8-microm spectral regions. All data were taken at both room temperature and 220 K. The uncertainty of the measured values of linewidths was estimated to <4%. From these data, the exponent n of the temperature dependence of linewidths was experimentally determined for the first time, for the systems N(2)O-N(2)O, N(2)O-N(2), and N(2)O-O(2). In the first two cases, it was shown that n is nearly J-independent, whereas it seems to vary linearly for N(2)O-O(2). Finally the values of N(2)O air-broadened linewidths were derived for the two temperatures 295 K and 220 K representing the upper and lower boundaries of middle atmosphere temperatures.

Stratospheric N(2)O mixing ratio profile from high-resolution balloon-borne solar absorption spectra and laboratory spectra near 1880 cm(-1)

A nonlinear least-squares fitting procedure has been used to derive the stratospheric N(2)O mixing ratio profile from balloon-borne solar absorption spectra and laboratory spectra near 1880 cm(-1). The atmospheric spectra were recorded during sunset from a float altitude of 33 km with the University of Denver 0.02-cm(-1) resolution interferometer near Alamogordo, N.M. (33 degrees N), on 10 Oct. 1979. The laboratory data were used to determine the N(2)O line intensities. The measurements indicate an N(2)O mixing ratio of 264 ppbv near 15 km decreasing to 155 ppbv near 28 km.

Spectroscopic Detection of Stratospheric Hydrogen Cyanide

A number of features have been identified as absorption lines of hydrogen cyanide in infrared spectra of stratospheric absorption obtained from a high-altitude aircraft. Column amounts of stratospheric hydrogen cyanide have been derived from spectra recorded on eight flights. The average vertical column amount above 12 kilometers is 7.1 +/- 0.8 x 10(14) molecules per square centimeter, corresponding to an average mixing ratio of 170 parts per trillion by volume.