The Transport of Nitric Oxide by the Mean Circulation and Planetary Waves

Abstract

The effects of the zonal mean circulation and planetary-wave winds on the distribution of nitric oxide in the 55?120 km height region is investigated. A time-dependent numerical model is used to investigate the interaction between planetary waves and the zonal mean circulation, and the effect of the circulation on the nitric oxide distribution is determined. The initial nitric oxide (NO) distribution is obtained by using a simple source/sink chemistry, vertical eddy diffusion, and advective transport by the zonal mean circulation. Changes in the initial NO distribution which result from the addition of planetary-wave winds are described. Planetary waves are found to induce a wave-like structure in the nitric oxide distribution which resembles that derived from observational data. Planetary waves can affect the nitric oxide concentration in two ways: first,through the wave-induced changes in the mean meridional circulation, and second, through the nitric oxide perturbation induced by wave winds themselves. The changes in total nitric oxide are due primarily to the zonal asymmetries in nitric oxide induced by the planetary waves. Implications of this result for explaining the winter anomaly are discussed.