CEDAR Postdoc: Determination of Charged Dust Characteristics in the Earth's Mesosphere Utilizing Radio Wave Modification

本项目将对极地中间层夏季回波（PMSEs）进行加热实验，作为表征这一现象所涉及的带电尘层的手段。顾名思义，pmse是在夏季极地中间层观测到的异常雷达回波；这些回波与带电尘埃或气溶胶粒子有关，由于可能与全球变化有关，因此引起当前相当大的兴趣。回声的确切产生机制是目前争论的一个话题，需要有关带电尘埃粒子密度和半径以及带电机制的信息。到目前为止，这些特征很难探索，但最近用无线电波积极修改PMSE以获得诊断信息的努力似乎很有希望：一旦理解了加热过程中不规则性的时间行为的坚定理论解释，就可以获得重要的带电尘埃特征信息，如尘埃密度和尘埃半径。该项目的目标是通过执行两项任务来发展这种能力：(1)开发和利用无线电波加热修正PMSE的新计算和分析模型；(2)参加计划于2007年和2008年夏季进行的欧洲非相干散射（EISCAT）修正实验。如果EISCAT的结果受到高工作频率的影响，该项目可能会要求在高频主动极光研究计划（HAARP）或高功率极光刺激（HIPAS）中进行后续加热实验。待开发的模型将纳入扩散效应、更精确的充电模型和等离子体温度演变，以及早期模型中未发现的特征，并将用于模拟不同尘埃参数下加热期间pmse的时间行为。观测数据将与模型结果进行比较，以改进模型并开发新的诊断能力。目标是为解释加热循环期间的时间电子密度行为提供坚实的理论基础，并最终为实验测量提供诊断预测。更广泛的影响包括支持大气区域耦合、能量学和动力学（CEDAR）项目的一名新博士后学者，而该实验最终将为未来PMSE修改和PMSE观测提供新的诊断仪器。研究结果可能对极地中层云和夜光云的研究有一定的参考价值。

This project is to perform heating experiments on polar mesosphere summer echoes (PMSEs) as a means to characterize the charged dust layer involved in this phenomenon. As the name states, PMSEs are anomalous radar echoes observed in the summer polar mesosphere; the echoes are associated with charged dust or aerosol particles and are of considerable current interest because of a possible connection with global change. The exact generation mechanism for the echoes is a current topic of debate, and information on the charged dust particle density and radius as well as on the charging mechanism is needed. These characteristics have been difficult to explore thus far but recent efforts to actively modify PMSE with radio waves to obtain diagnostic information appears promising: important charged dust characteristic information, like dust density and dust radius can be obtained once a firm theoretical interpretation of the temporal behavior of the irregularities during heating is understood. This project's goal is to develop this capability by performing two tasks: (1) develop and utilize new computational and analytical models of PMSE modification by radio wave heating; and (2) participate in the European Incoherent Scatter (EISCAT) modification experiments scheduled for the summers of 2007 and 2008. The project may request follow-on heating experiments at the High Frequency Active Auroral Research Program (HAARP) or the High Power Auroral Stimulation (HIPAS) if the EISCAT results are compromised due to high operating frequencies. The models to be developed will incorporate diffusion effects, more accurate charging models, and plasma temperature evolution, features not found in earlier models, and will be used to simulate the temporal behavior of PMSEs during heating episodes with varying dust parameters. The observational data will be compared with the model results to refine the model and to develop new diagnostic capabilities. The goal is to provide a firm theoretical foundation for interpreting the temporal electron density behavior during the heating cycle and ultimately developing diagnostic predictions for experimental measurements. The broader impacts include the support of a new postdoctoral scholar in the Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) program while the experiment will ultimately provide new diagnostic instruments for future PMSE modification and PMSE observation. The research results are likely to be beneficial for investigations of polar mesospheric and noctilucent clouds.