Ubiquity of quasi-horizontal layers in the troposphere
Fine laminar structures in the atmosphere have been described
previously, but their characterization has been limited. The modern
global coverage of aircraft flights offers an opportunity to provide
such a characterization, and examine the ubiquity of such structures,
in space and time. Research aircraft measuring vertical profiles of
atmospheric chemical constituents frequently discern quasi-horizontal
atmospheric layers with mean thicknesses of order 1 km and mean
altitudes between 5 and 7 km. These layers can be characterized and
categorized by various combinations of ozone, water vapour, carbon
monoxide and methane deviations from background profiles. Five
commercial aircraft have been recently equipped to measure water
vapour and ozone concentrations, and automatically collect vertical
profile information on landing and take-off. Here we synthesize
measurements from both reserach and commercial flights and demonstrate
the ubiquity in space and time of four layers types (as categorized by
their chemical signatures). Up to one-fifth of the lowest 12 km of
the atmosphere is occupied by such layers. We suggest that this
universality reflects basic characteristics of the atmosphere hitherto
unexplored, with potential implications for present understanding of a
wide variety of dynamic and chemical atmospheric processes.
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