用理论模式研究电离层F_1－ledge的变化

THEORETICAL MODEL STUDIES OF THE IONOSPHERIC F_1-LEDGE VARIATIONS

利用一个时变电离层理论模式，研究武昌地区（３０．５°Ｎ，１１４．４°Ｅ）电离层Ｆ_１－ｌｅｄｓｅ现象．表明利用当前关于中性气体和太阳辐射的经验模式，观测到的Ｆ_１－ｌｅｄｇｅ出现与演化的基本规律将可基于现有电离层理论加以再现．指出较明显的Ｆ_１－ｌｅｄｇｅ结构同较低的中性原子－分子含量比有直接关系，并同原子－分子成份的过渡高度、背景温度及其垂直分布形态有一定联系．同Ｆ_１－ｌｅｄｇｅ形态相关联的Ｆ_１－Ｆ_２谷，其出现主要是由于亚稳态氧离子参与光化过程，以及电离气体参与具有一定垂直变化的输运过程．

The F_1 -ledge behaviour in Wuchang(30.5°N,114.4°E) is studied with the help of a time-dependent theoretical ionospheric model.It is shown that the current ionospheric theories are eligible to repfoduce the observed regularity of the F_1-ledge occurrence and evolution within the atmospheric background defined by the up-todate empirical models. And the simulations reveal that a pronounced ledge correlates directly to a lower ratio of neutral atomic oxygen to molecular compositions, and has something to do with the transition height from the prevailing molecular to atomic ions, and with the background temperature and its height gradient. The F_1-F_2 valley, connected to the F_1-ledgd shape,is considered to be Present with the chemical processes that involve reactons of meta -stable oxyen ions ,as well as the dynamic processes that contain a proper vertical variation of ion movements.