Showing papers by "Michael R. Gunson published in 1998"

Correlations of Stratospheric Abundances of CH4 and N2O Derived from ATMOS Measurements

Abstract: Atmospheric Trace MOlecule Spectroscopy (ATMOS) measurements made over a wide range of altitudes and latitudes demonstrate compact correlations between mixing ratios of CH, and N,O. Tight but distinct correlations are observed for the tropics, the springtime Arctic vortex, and the extra-tropics/extra-vortex regions, indicating dynamical isolation between these regions. Little variability is apparent in correlations between CH4 and N20 from measurements made in different years (1992, 1993, and 1994), seasons (March/April and November), and hemispheres.

Atmos/atlas 3 infrared profile measurements of trace gases in the november 1994 tropical and subtropical upper troposphere

Abstract: Vertical mixing ratio profiles of four relatively long-lives gases, HCN, C2H2, CO, and C2H6, have been retrieved from 0.01/cm resolution infrared solar occultation spectra recorded between latitudes of 5.3degN and 31.4degN. The observations were obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Science (ATLAS) 3 shuttle flight, 3-12 November 1994. Elevated mixing ratios below the tropopause were measured for these gases during several of the occultations. The positive correlations obtained between the simultaneously measured mixing ratios suggest that the enhancements are likely the result of surface emissions, most likely biomass burning and/or urban industrial activities, followed by common injection via deep convective transport of the gases to the upper troposphere. The elevated levels of HCN may account for at least part of the "missing NO," in the upper troposphere. Comparisons of the observations with values measured during a recent aircraft campaign are presented.

Atmos/atlas 3 infrared profile measurements of clouds in the tropical and subtropical upper troposphere

Abstract: Vertical profiles of infrared cirrus extinction have been derived from tropical and subtropical upper tropospheric solar occultation spectra. The measurements were recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Sciences (ATLAS) 3 shuttle flight in November 1994. The presence of large numbers of small ice crystals is inferred from the appearance of broad extinction features in the 8-12 micron region. These features were observed near the tropopause and at lower altitudes. Vertical profiles of the ice extinction (/km) in microwindows at 831, 957, and 1204/cm have been retrieved from the spectra and analyzed with a model for randomly oriented spheroidal ice crystals. An area-equivalent spherical radius of 6 gm is estimated from the smallest ice crystals observed in the 8-12 micron region. Direct penetration of clouds into the lower stratosphere is inferred from observations of cloud extinction extending from the upper troposphere to 50 mbar (20 km altitude). Cloud extinction between 3 and 5 micron shows very little wavelength dependence, at least for the cases observed by the ATMOS instrument in the tropics and subtropics during ATLAS 3.