大气重力波引起的突发钠层的模拟研究

SIMULATION AND RESEARCH OF SUDDEN SODIUM LAYER GUIDED BY GRAVITY WAVES

应用钠原子和中性大气分子的质量连续性方程来模拟突发钠层（SSL）,垂直风场采用接近实际大气重力波的正弦行波模式,结果较好地反映了SSL的形成过程.SSL的形成时刻在5-15min之间并可持续到30min之后,形成高度大约在90-100km之间,峰宽为0.5-2km之间,这些都与实际观测SSL的特点相符.同时还进一步地研究了当重力波参数（主要指垂直波长和周期）、风速以及常态钠层半宽度发生变化时SSL的变化趋势.

The causes of formation of sudden sodium layer are not confirmed. The main viewpoints include effects of meteor ablation, dust release and atmosphere dynamics. To research into the influence of atmosphere dynamics to formation of sudden sodium layer, we simulate sudden sodium layer by applying the continuity equations for both atomic sodium and the background neutral atmosphere. As far as vertical winds are concerned, we adopt the model of a sine travelling wave which approaches the real one. The results reflect the process of sudden sodium layer's formation and development. The instant of sudden sodium layer's formation is from 5-minute to 15-minute and sudden sodium layer can last to 30-minute. The altitude of sudden sodium layer is from 90-kilometer to 100-kilometer. The width of sudden sodium layer is from 0.5 kilometers to 2 kilometers. All these are in agreement with the data obtained. And this paper also researches the tendency of sudden sodium layer's development when the parameters of gravity waves alter, including vertical wave length, wave period, velocity of the vertical winds and half-width of normal sodium layer. In all these factors, velocity of the vertical winds and half-width of normal sodium layer influence the formation of sudden sodium layer greatly. To validate the reliability of the simulation, this paper provides two cases of observation. Comparing the result of the simulation with the observation, we find that they are close to each other.