New empirical models of the electron temperature and density in the Venus ionosphere with application to transterminator flow
New empirical models of the electron temperature and density in the Venus ionosphere with application to transterminator flow
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金星电离层电子温度和密度的新经验模型及其应用于终结者流
DOI：
10.1029/ja089ia03p01477
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发表时间：
1984
影响因子：
--
通讯作者：
H. G. Mayr
中科院分区：
文献类型：
--
作者：
R. Theis;L. H. Brace;R. Elphic;H. G. Mayr
近日点的持续上升使得先锋金星轨道器（PVO）能够遇到金星电离层的大片区域，而这些区域在早先使用推进装置来维持电离层深处的近日点时是没有采样的。我们利用轨道电子温度探测器在金星的前7年（1978年12月- 1982年12月）的测量数据，设计了新的电子温度Te和密度Ne的经验模型。与我们之前使用球面谐波来描述Ne的太阳天顶角变化不同（Theis et al., 1980），我们发现这个更完整的数据集可以通过太阳天顶角的误差函数和指数以及海拔的幂律变化来更好地描述。该模型比以前的模型有了显著的改进，因为它允许分别对黎明和黄昏扇区进行建模，提供了更真实的终端附近梯度的表示以及这些梯度随高度的变化。我们使用这些模型来执行动量方程的二维解，该动量方程被认为是夜间离子流速度的主要原因，该速度被认为是维持夜间电离层的主要原因。终点处的速度从150公里处的中性大气风速（~ 300米/秒）上升到500公里以上超过2000米/秒的峰值速度，与该地区PVO测量的离子漂移基本一致。
The continuing rise of periapsis has allowed the Pioneer Venus orbiter (PVO) to encounter vast regions of the Venus ionosphere that were not sampled earlier when propulsion was being used to maintain periapsis deep in the ionosphere. We have employed the orbiter electron temperature probe measurements from the first seven Venus years (December 1978–December 1982) to devise new empirical models of electron temperature Te and density Ne. Departing from our earlier use of spherical harmonics to describe the solar zenith angle variations of Ne (Theis et al., 1980), we find that this more complete data set can be described better by error functions and exponentials in solar zenith angle and power law variations in altitude. This model represents a significant improvement over the previous models, as it allows the dawn and dusk sectors to be modeled separately, providing more realistic representations of the gradients near the terminators as well as the variation of those gradients with altitude. We employ these models to perform a two-dimensional solution of the momentum equation for the nightward ion flow velocities believed to be largely responsible for the maintenance of the nightside ionosphere. The velocities at the terminator rise from the neutral atmospheric wind velocity (∼300 m/s) at 150 km to a peak velocity exceeding 2000 m/s above 500 km, in general agreement with PVO measurements of ion drift in that region.