Diffusive separation of the lower atmosphere

Adachi, Y, Kawamura K, Armi L, Keeling RF.  2006.  Diffusive separation of the lower atmosphere. Science (Washington). 311:1429-1429.: American Association for the Advancement of Science, 1200 New York Avenue, NW Washington DC 20005 USA, [mailto:membership@aaas.org], [URL:http://www.aaas.org]


Air sampling, Ar/N2 ratio, argon, ASFA 2: Ocean Technology Policy & Non-Living Resources, atmosphere, Atmospheric boundary layer, Atmospheric chemistry, Atmospheric composition, Atmospheric gases, diffusion, Earth atmosphere, Gravity effects, inversion, Inversions, M2 551.510.3/.4:Physical Properties/Composition (551.510.3/.4), Meteorological & Geoastrophysical Abstracts, Near-surface layer, Nighttime, nitrogen, P 0000:AIR POLLUTION, Pollution Abstracts, Q2 02188:Atmospheric chemistry, ratios, Temperature differences, Temperature effects, Tropospheric composition, Turbulent mixing


The separation of atmospheric constituents by gravity has been proposed theoretically for almost two centuries. However, turbulent mixing has prevented the detection of this phenomenon in the lower atmosphere. By using precise measurements of the Ar/N2 ratio of air samples taken under strong nocturnal inversions, we have detected such separation in near-surface layers. The effect is shown to be consistent with combined influence of thermal and gravimetric separation, with the thermal contribution being more important.