To
examine vertical distributions of the O2/N2 ratio in the stratosphere, air
samples were collected using a cryogenic sampler over Sanriku,
Japan and Syowa, Antarctica. It
was clearly seen that d(O2/N2), as well as
simultaneously measured d15N of N2 and d18O of O2, decreased
gradually with increasing height in the stratosphere. The observed profiles of
stratospheric ï€ d15N and d18O were in good agreement
with those calculated using a steady state
1-dimensional eddy-diffusion/molecular-diffusion model suggesting that the
upward decrease of stratospheric d(O2/N2)
is caused by O2 and N2 molecules fractionated differently
by gravity. The stratospheric d(O2/N2) corrected for the
gravitational separation indicated that the average value at heights above
20-25 km over Sanriku was always higher than
the upper tropospheric d(O2/N2)
value over Japan
at the corresponding time, and that it has decreased secularly, as was found in
the troposphere.
Author: Shigeyuki Ishidoya, Satoshi Sugawara, Gen Hashida, et al (ishidoya at caos-a dot geophys dot tohoku dot ac dot jp)
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