Remote sensing of the large-scale circulation of atomic oxygen

摘要

Observations of the atomic oxygen green line airglow at 557.7 nm began in England with Lord Rayleigh IV in 1923. The large-scale circulation of the atmosphere is now well known, producing a mesopause that is cold in summer and warm in winter. The corresponding transport of atomic oxygen should produce high airglow emission rates in winter, and low values in summer. Thus remotely sensed airglow observations are potentially capable of providing a record of the large-scale circulation of the thermosphere. Here a search is made for the signature of the large-scale circulation using data from the WIND Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite, and model results from the TIME-GCM model, making use of earlier ground-based results as well. However, the signature of this circulation is not readily found. In the tropical region a well-defined semi-annual variation of emission rate is identified; this appears to result from the semi-annual variation of the diurnal tide. At mid- and high latitudes a pronounced annual variation is found with an emission rate maximum in the autumn in both hemispheres. At still higher latitudes ground-based observations show this strong autumn maximum, with deep depletion of atomic oxygen in the springtime.