CEDAR: Atmospheric Neutral Density Dynamics through Meteor Observations

该奖项是一项试验性努力，旨在进一步开发一种新的测量技术，通过对流星轨迹的雷达观测来估计中性密度。当流星体进入地球大气层时，它们会经历大气阻力的减速，并形成雷达可以观测到的流星，提供了一个信息源，可以独立确定80至140公里高度的大气中性密度。测量这一区域的中性密度在实验上是非常具有挑战性的，这项工作将通过使用一种新的技术来填补这一空白。了解中性密度很重要，因为低地球轨道卫星的大气阻力与密度有很大关系。继续积累表征这一流星体群体的数据还将改进对航天器操作员和卫星数据地面用户的风险评估。这项工作还将为新的研究生提供研究课题，这项工作的成果将被纳入航空航天本科生和研究生课程。将通过在两个不同地理位置的雷达设施上同时进行流星雷达运动，并应用一种新的统计技术从探测到的流星轨迹得出中性密度值，来研究80至140公里高度的中层-低热层区域中性密度的纬度和时间变化。这些对大气中性密度的测量将与现有的大气模型进行比较，以确定短期密度变化的来源，并评估它们将在多大程度上与高层大气的密度增强相耦合。由此产生的总中性密度的测量将补充对温度、风、等离子体和单个金属物种的测量，并提供现有中性密度测量的替代数据来源，这些测量是稀疏的或取决于不同的物理假设。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award is an experimental effort to further develop a new measurement technique for estimating neutral densities by using radar observations of meteor trajectories. As meteoroids enter the Earth's atmosphere, they experience deceleration due to atmospheric drag and form meteors that radar can observe, providing a source of information that can independently determine the neutral density of the atmosphere at altitudes of 80 to 140 km. Measurements of neutral densities in this region are very challenging experimentally and this work will fill this gap by using a novel technique. Knowledge of neutral densities is important since low-Earth-orbit satellites experience atmospheric drag that is strongly dependent on densities. The continued accumulation of data characterizing this meteoroid population would also provide improved risk assessment to spacecraft operators and to ground-based users of satellite data. This work will also provide research topics for new graduate students and results from this work will be incorporated into undergraduate and graduate courses in Aeronautics and Astronautics.The latitudinal and temporal variation of neutral density in the mesosphere-lower-thermosphere region between 80 and 140 km in altitude will be studied by conducting a simultaneous meteor radar campaign at two geographically distinct radar facilities and applying a novel statistical technique to derive neutral density values from the detected meteor trajectories. These measurements of atmospheric neutral density will be compared against existing atmospheric models to characterize the origins of short time density variations and to assess the extent that they will couple to density enhancements in the upper atmosphere. The resulting measurements of total neutral density will complement measurements of temperature, winds, plasma, and individual metallic species, and provides an alternative source of data to existing neutral density measurements that are sparse or that depend on different physical assumptions.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.