Self-consistent modeling of the auroral ionosphere-thermospher : how does sever space weather affect low-earth orbiting satellites?

这项研究计划的主要目标是调查太阳活动如何影响高纬度地区的地球上层大气。特别是，该计划将着手对电离层-热层对极端太阳活动的响应进行自洽模拟和探索，并研究低地球轨道卫星(LEOS)如何受到这些变化的影响。 最近利用空间监视网络双线元素集进行的研究表明，太阳活动对在轨卫星的高度有可检测的影响。特别是，已经观察到，所谓的“死卫星”的高度变化率与F10.7太阳通量指数和AP指数的变化率类似。使用“失效卫星”使我们可以忽略由于卫星操作员的操作而引起的高度变化。因此，轨道参数的任何变化都可以被认为是由于热层密度、热层风或两者的组合造成的。 我们方法的新奇之处在于，我们将使用RMC最近开发的热层-电离层耦合模型，以自洽的方式模拟空间环境。该模型是一个二维时间相关代码，它计算了主要热层和电离层物种的数密度、它们的温度以及离子和电子的场向速度的时间演变。可以计算电离层-热层系统的电势、电场、电流密度和电导率随粒子降水变化的时间演化。这些模拟将作为轨道传播子程序的输入，使我们能够模拟低轨卫星的轨道以及严重太阳风暴对其轨道参数的影响。

The main objective of this research program is to investigate how solar activity affects the Earth's upper atmosphere at high latitudes. In particular, this program will set out to self-consistently model and explore the ionospheric-thermospheric response to extreme solar activity and study how Low-Earth Orbiting satellite (LEOs) can be affected by these changes. Recent studies using the Space Surveillance Network Two-Line Element sets has shown that solar activity has a detectable influence on the altitude of orbiting satellites. In particular, it has been observed that the rate-of-change of the altitude of so-called "dead satellites" varies in a similar way as the rate-of-change in the F10.7 solar flux index and Ap index. Using "dead satellites" allows us to neglect changes in the altitude that are due to maneuvers by the satellite operator. As a result, any changes in the orbital parameters can be considered to be due to changes in the thermospheric density, the thermospheric winds or a combination of both. The novelty in our approach is that we will use a coupled thermospheric-ionospheric model that has been recently developed at RMC to model the space environment in a self-consistent manner. The model is a two-dimensional time-dependent code that computes the temporal evolution of the number densities of the principal thermospheric and ionospheric species, their temperatures, and the field-aligned velocities of the ions and electrons. The temporal evolution of the electric potential, the electric fields, the current densities and the conductivities of the ionospheric-thermospheric system in response to variations in the particle precipitation can be computed. These simulations will serve as input for orbital propagation subroutines allowing us to model the orbit of LEOs and the effects of severe solar storms on their orbital parameters.