The concentration of molecular H2 and CH4 in the stratosphere
Tóm tắt
Stratospheric profiles of CH4 and H2 over eastern Texas have been derived up to 31 km altitude from air samples collected aboard a balloon and analyzed by gas chromatography. For H2, contamination during flight and measurement presented a problem which has been resolved only recently. The earlier profiles require corrections which are rather large for the highest altitudes. The three profiles indicate an increase of the H2 concentration in the lower stratosphere from about 0.5 p.p.m. per volume at the tropopause to about 0.8 p.p.m. at around 27 km altitude. Above that altitude the H2 concentration decreases again. An air sample collected between 44 and 62 km by a rocket-borne cryogenic sampler had an H2 concentration of 0.4 p.p.m. The five CH4 profiles showed a decrease in CH4 concentration with altitude generally with a steeper gradient directly above the tropopause and a weaker gradient at higher altitudes reaching 0.9 p.p.m. at 30 km altitude. The CH4 concentration in the rocket sample was 0.25 p.p.m., in good agreement with the gradient obtained from the balloon samples.
Tài liệu tham khảo
A. E. Bainbridge andL. E. Heidt,Measurements of methane in the troposphere and lower stratosphere, Tellus18 (1966), 221–225.
D. H. Ehhalt andL. E. Heidt, Vertical Profiles of CH4 in the Troposphere and Stratosphere, Proc. Sym. Sources, Sinks and Concentrations of Carbon Monoxide and Methane in the Earth's Environment, August 15–17, 1972, St. Petersburg Beach, Fla. pp. 11-1–11-11.
D. H. Ehhalt, L. E. Heidt andE. A. Martell,The concentration of atmospheric methane between 44 and 62 kilometers altitude, J. Geophys. Res.77 (1972), 2193–2196.
L. E. Heidt andD. H. Ehhalt,Gas chromatographic measurement of hydrogen, methane and neon in air, J. Chromatog.,69 (1972), 103–113.
E. Hesstvedt,On the photochemistry of ozone in the ozone layer, Geophys. Publ. Norway27 (1968), 1.
H. Levy,Normal atmosphere: large radical and formaldehyde concentrations predicted, Science173 (1971), 141.
S. Manabe andB. G. Hunt,Experiments with a stratospheric general circulation model, I. Radiative and dynamic aspects, Mon. Wea. Rev.96 (1968), 477.
H. J. Mastenbrook,Water vapor distribution in the stratosphere and high troposphere, J. Atmo. Sci.25 (1968), 299.
J. C. McConnell, M. B. McElroy andS. C. Wofsy,Natural sources of atmospheric CO, Nature223 (1971), 187.
R. D. McQuigg andJ. G. Calvert,The photodecomposition of CH 2 O, CD 2 O, CHDO and CH 2 −CD 2 O mixtures at xenon flash lamp intensities, J. Am. Chem. Soc.91 (1969), 1590.
M. Nicolet,Ozone and hydrogen reactions, Ann. Geophys.26 (1970), 531.
T. G. Scholz, D. H. Ehhalt, L. E. Heidt andE. A. Martell,Water vapor, molecular hydrogen, methane and tritium concentrations near the stratopause, J. Geophys. Res.75 (1970), 3049–3054.