不同上边界条件下的极区电离层数值模拟

The Influence of Upper Boundary Conditions on the Polar Ionosphere

利用一维自洽的极区电离层模型,研究了沿磁力线方向不同电离层-磁层耦合条件下极区电离层的响应。此模型在110—610 km的电离层空间区域内,综合求解描述极区电离层的连续性方程、动量方程和能量方程,以得到电离层数值解。研究发现,上边界条件在200 km以上的高度能显著地影响电离层参量的形态。较高的O^+上行速度对应较低的F层峰值和较高的电子温度。不同边界O^+上行速度对应的温度高度剖面完全不同。200km以上电子温度高度剖面不但由来自磁层的热流通量所控制,同时还受到场向O^+速度的影响。对利用电离层模型研究电离层内部物理过程提出了建议。

A one-dimensional high-latitude ionospheric model, in which the continuity, momentum and energy equations are solved self-consistently in the altitude range between 110 and 610km, is used to study the ionospheric responses to different upper boundary conditions. It is found that upper boundary conditions may influence significantly profiles of ionospheric quantities at higher altitudes. A larger upward O^＋ velocity at the upper boundary results in lower hmF2 and F region electron densities, and consequently higher electron temperatures. The difference in hmF2 between an upper boundary velocity of 0.0 m/s and 200 m/s reaches about 76 km. The altitude profiles of temperatures are quite different from each other corresponding to different upward ion velocities and heat fluxes from the magnetosphere. The Coulomb collisions between electrons and ions play an important role in shaping the electron temperature profiles at altitudes higher than the hmF2. The simulated electron temperature height profiles are similar to the measurements made in earlier studies. The altitude profile of electron temperature above 200 km is influenced by both downward heat fluxes and field-aligned O^＋ velocities, while the ion temperature and the electron density have their responses at altitudes higher than 250km. Proposals are given while specifying the upper boundary conditions in the simulation of the high-latitude ionosphere.