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

这个项目是对极地中间层夏季回波(PMSE)进行加热实验，以此作为描述与这一现象有关的带电尘埃层的一种手段。顾名思义，PMSE是在夏季极地中间层观测到的异常雷达回波；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，因此具有相当大的电流兴趣。回波的确切产生机制是当前争论的主题，需要关于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：一旦理解了加热期间不规则现象的时间行为的确切理论解释，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一能力：(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)参加定于2007年和2008年夏季进行的欧洲非相干散射修正试验。如果EISCAT结果因高工作频率而受到影响，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。将要开发的模型将包括扩散效应、更精确的充电模型和等离子体温度演变，这些都是早期模型中没有的特征，并将用于模拟不同粉尘参数的加热时段中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。其目的是为解释加热循环中的时间电子密度行为并最终为实验测量提供诊断预测提供坚实的理论基础。更广泛的影响包括一位新的博士后学者在大气区域耦合、能量和动力学(CEDAR)计划中的支持，而该实验最终将为未来的PMSE修改和PMSE观测提供新的诊断工具。这一研究结果可能对极地、中层和夜光云的研究有所裨益。

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.