The Impact of Energetic Neutral Particles Raining Down on the Thermosphere due to Charge Exchange Reactions in the Upper Ionosphere and Polar Wind

极地地区的高层大气包含一层弱电离气体（电离层）。电离粒子如氢离子和氧离子响应于通过电场和来自近地空间的粒子沉淀的加热而向上漂移，并且氢的速度可高达10-20 km/s，氧的速度可高达3-5 km/s。这些高能离子与周围的中性气体（热层）相互作用，在电荷交换反应中产生高能中性原子。轻的氢原子会逃逸出大气层，但重的中性物质（如氧）则无法逃逸并逆转方向。在极冠电离层-热层系统中，这引起了连续的极地雨。该奖项将研究高能中性粒子如何影响电离层-热层耦合系统中的环流、温度、密度和波活动。这项研究将包括以前未包括的高能中性粒子的影响，并提供所需模型分辨率的更好规格，从而有助于空间等离子体扰动建模的社区努力。该项目还将支持一名研究生，并有助于创造一个多元化的劳动力。这项工作将涉及（1）在流体方程中加入新的项，以解释目前未考虑的离子-中性和中性-中性耦合的其他类型，包括由于与背景中性粒子碰撞而导致的高能原子冷却引起的热损失，（2）使用各种条件下的耦合模型运行一组全面的模拟，以及（3）调查不同干扰类型的影响。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The upper atmosphere in the polar regions contains a layer of weakly ionized gas (the ionosphere). Ionized particles such as hydrogen and oxygen ions drift upward in response to heating via electric fields and particle precipitation from the near-Earth space and can reach velocities as high as 10-20 km/s for hydrogen and 3-5 km/s for oxygen. These energetic ions interact with surrounding neutral gas (the thermosphere) and energetic neutral atoms are produced in charge exchange reactions. Light hydrogen atoms escape the atmosphere but heavy neutral species such as oxygen cannot escape and reverse direction. In the polar cap ionosphere-thermosphere system, this gives rise to a continuous Polar Rain. This award will investigate how the energetic neutrals affect circulation, temperature, density, and wave activity in the coupled ionosphere-thermosphere system. The research will contribute to the community effort of modeling of space plasma disturbances by including previously unincluded effects of the energetic neutral particles and by providing a better specification of the required model resolutions. The project will also support a graduate student and contribute to creating a diverse workforce. The work will involve (1) inclusion of new terms in the fluid equations to account for additional types of the ion-neutral and neutral-neutral coupling that are currently not considered, including thermal loss due the energetic atom cooling due to collisions with background neutrals, (2) running a comprehensive set of simulations using the coupled models for various conditions, and (3) investigating effects of different disturbance types.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.