CEDAR: Investigating Helium Behavior and Its Role in the Thermosphere

这个项目阐述了支配氦在整个热层的行为的基本物理过程，并阐明了它在理解其他热层成分的行为方面的作用。热层是许多低地球轨道卫星的领域，其组成、它们的传输特性和它们的整体运动对卫星阻力有很大的贡献。在目前的热层大气环流模式中，氦一直是缺失的组分，它通过对总质量密度的影响，在确定卫星在高层热层中的阻力效应方面发挥着重要作用。此外，氦是一种很好的动力学示踪剂，创造了使用氦观测来描述热层中测量不佳的风系统的可能性。该项目涉及了解地球空间系统复杂性的方法，并将作为科罗拉多大学和NCAR之间的合作进行。两名研究生将参与这个项目。通过这一奖项，将完成在NCAR社区模型中全面描述海拔、纬度、经度、当地时间、季节、太阳周期和地磁活动中的氦结构的计划的实施。然后，这个新方案将被用来评估导致氦的分布和变化的过程。然后，这种理解可以被投射到其他气体，这些气体的整体结构和行为是复杂的，但与氦相比，可以评估其对运输的依赖性。对成分的动力学影响也影响了对总质量密度的估计，太阳极小期间的氦可能对总质量密度有直接贡献。这项工作将有助于更好地描述热层，并可用于改进卫星阻力研究。模型输出将与卫星观测结果进行比较以进行评估。

This project addresses fundamental physical processes that govern the behavior of helium throughout the thermosphere and also elucidates its role in understanding the behavior of other thermospheric constituents. The thermosphere is the domain for many low-earth-orbiting satellites and the constituent makeup, their transport properties, and their bulk motion contribute significantly to satellite drag. Helium has been a missing constituent in current thermosphere general circulation models and plays an important role in determining satellite drag effects in the upper thermosphere through its impact on the total mass density. Additionally helium is an excellent dynamical tracer creating the possibility of using helium observations to describe the poorly measured wind systems in the thermosphere. The project addresses ways of understanding complexity in the geospace system and will be carried out as a collaboration between the University of Colorado and NCAR. Two graduate students will be involved in the project. Through this award, the implementation of a scheme to fully describe helium structure in altitude, latitude, longitude, local time, season, solar cycle and geomagnetic activity in NCAR community models will be completed. This new scheme will then be used to evaluate the processes responsible for the distribution and variation of helium. This understanding can then be projected to other gasses whose overall structure and behavior are complex but, by contrasting with helium, can be evaluated for its transport dependencies. The dynamical influences on composition also impact estimates of total mass density, where helium during solar minima can have a direct contribution. This work will lead to a better characterization of the thermosphere and can be used to improve satellite drag studies. Model output will be compared with satellite observations for evaluation.