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的带电尘埃。 这种带电尘埃的特性和相关的物理过程是高层大气空间科学的前沿问题，因为它可能与全球气候变化密切相关。 在过去十年中，利用天基测量来表征这种带电尘埃并将这种带电尘埃的存在与称为极地中间层夏季回波（PMSE）的迷人地基无线电信号相关联，取得了重大进展。 PMSE是由电子不规则性散射引起的，电子不规则性是由于电子带电到不规则的尘埃密度上而引起的。 由于天基测量仍然难以准确进行，因此利用地基PMSE特征来确定尘埃特征的独立方法将是提供诊断能力的重要一步。 最近，它已被证明，PMSE可以通过加热源区域与地面电离层无线电波加热设施进行修改。 的PMSE在加热周期的时间演变表现出巨大的潜力，用于表征灰尘层，因为这种时间演变已被预测为直接相关的PMSE源区域中的灰尘的物理特性。 然而，目前的模型的时间演变的不规则性与PMSE在加热循环过程中是有限的，并不能利用所有的信息可用的不规则性时间演变的更准确的描述。 这里所涉及的研究将导致一个更准确的模型的时间演变的电子不规则性，认为在无线电波加热过程中产生PMSE的发展。 这项研究将利用这种更准确的描述的不规则性的时间演变提供直接的诊断信息，以表征灰尘层。实验将从模型计算的预测中发展出来。 实验将集中在修改高频（HF）PMSE的调查，其中重要的新的物理过程被预测存在，还没有被研究过去的工作，集中在调查修改甚高频（VHF）PMSE。 将在阿拉斯加的一个电离层加热设施进行实验观测，以证实和改进模型和模型预测。 该设备非常适合进行这样的实验研究。 最终，研究计划将提供一个整体的方法来开发更好的诊断特征的带电尘埃层，也有助于了解PMSE的生成。 这项研究将通过研究生培训支持人力资源开发。 这项工作还将有助于支持研究机构内部的基础设施和协作工作，由于最近采取了扩大高层大气空间科学研究的内部举措，这一点很重要。 最后，将利用这项工作的实验部分，使科学和工程专业人数不足的大学本科生和高中生在调查人员所在机构接触空间科学。

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.