Radio Frequency Modification of Dust-Associated Irregularities in the Polar Summer Mesosphere

研究人员将进行一项实验和理论研究计划，以表征夏季极地中间层中的带电尘埃。这种带电尘埃及其相关物理过程的表征是高层大气空间科学的一个前沿问题，因为它可能与全球气候变化密切相关。在过去的十年里，利用太空测量来表征这种带电尘埃的特征，并将这种带电尘埃的存在与一种名为极地中间层夏季回波（PMSE）的迷人地面无线电信号联系起来，取得了重大进展。pmse的产生是由于电子对不规则尘埃密度的电荷而引起的电子不规则散射。由于基于空间的测量仍然难以准确地进行，因此利用基于地面的PMSE特征来表征尘埃的独立方法将是提供诊断能力的重要一步。最近的研究表明，可以通过地面电离层无线电波加热设备加热源区域来改变pmse。热循环期间PMSE的时间演变与PMSE源区粉尘的物理特征直接相关，因此对表征尘层具有巨大的潜力。然而，在加热周期中与PMSE相关的不规则时间演变的现有模型是有限的，并且不能利用所有可用的信息来更准确地描述不规则时间演变。这里涉及的研究将导致开发一个更精确的模型，用于在无线电波加热期间产生PMSE的电子不规则性的时间演化。本研究将利用这种对不规则时间演变的更准确描述，为表征尘埃层提供直接的诊断信息。实验将从模型计算的预测中展开。实验将集中于研究高频（HF） PMSE的修改，其中预测存在重要的新物理过程，而过去的工作主要是研究甚高频（VHF） PMSE的修改。实验观测将在阿拉斯加的电离层加热设施进行，以证实和改进模型和模型预测。这个设备非常适合进行这样的实验研究。最终，该研究计划将提供一种全面的方法来开发更好的诊断方法，以表征带电粉尘层，并有助于了解PMSE的产生。这项研究将通过培养研究生来支持人力资源开发。这项努力还将有助于支持研究机构内部的基础设施和协作工作，由于最近扩大高层大气空间科学研究的内部倡议，这一点很重要。最后，这项工作的实验部分将被利用，让代表性不足的本科学院和高中学生在研究人员的家乡机构接触空间科学。

The investigators will conduct an experimental and theoretical research program to characterize charged dust in the summer polar mesosphere. The characterization of this charged dust and the associated physical processes is a forefront issue in upper atmospheric space science due to the possible intimate relationship with global climate change. Significant progress has been made in the last decade using space-based measurements to characterize this charged dust and correlate the existence of this charged dust with a fascinating ground-based radio signature called Polar Mesospheric Summer Echoes (PMSE). PMSEs result from scattering from electron irregularities which are due to electron charging onto the irregular dust density. Since space-based measurements are still difficult to make accurately, an independent method of characterizing the dust utilizing the ground-based PMSE signatures would be a significant step forward in providing diagnostic capabilities. Recently it has been shown that PMSEs can be modified by heating the source region with a ground-based ionospheric radio wave heating facility. The temporal evolution of the PMSEs during the heating cycle shows tremendous potential for characterizing the dust layer since this temporal evolution has been predicted to be directly related to the physical characteristics of the dust in the PMSE source region. However, current models of the temporal evolution of the irregularities associated with PMSE during the heating cycle are limited and not able to exploit all of the information available with a more accurate description of the irregularity temporal evolution. The study involved here will result in the development of a much more accurate model for the temporal evolution of the electron irregularities believed to produce PMSE during radio wave heating. This study will utilize this more accurate description of the irregularity temporal evolution to provide direct diagnostic information to characterize the dust layer. Experiments will be developed from the predictions of the model calculations. The experiments will concentrate on investigation of modifying High Frequency (HF) PMSE where important new physical processes are predicted to exist which have not been studied by past work which has concentrated on investigating modifying Very High Frequency (VHF) PMSE. Experimental observations will be performed at an ionospheric heating facility in Alaska to corroborate and refine the model and model predictions. This facility is well suited for such an experimental study. Ultimately, the research plan will provide a holistic approach to the development of better diagnostics for characterizing the charged dust layer and also contribute to an understanding of PMSE generation. This study will support human resource development through graduate student training. The effort will also serve to support infrastructure and collaborative work internally within the investigators' institution which is important due to the recent internal initiative to expand upper atmospheric space science research. Finally, the experimental component of the work will be utilized to expose underrepresented undergraduate college and high school students in science and engineering to space science at the investigators' home institution.