D-Region Ionosphere Inferred Maps of Electron-density (DRIIME)

授予格鲁吉亚理工大学的合同将支持一项举措，即利用甚低频（3-30千赫，周期33-333微秒）无线电接收器建立60-90公里高度电离层等离子体长期空间测绘能力。虽然利用全球定位系统对电子总含量的测量通过遥感获得了250公里以上高度的高层大气等离子体分布的空间图，但目前还没有这种能力来测量这一低电离层等离子体区域。甚低频遥感长期以来一直被认为是这一区域最有前途的遥感技术，但由于若干因素，很难从甚低频测量结果得出电离层图。然而，最近在电离层诊断方面取得的两项进展现已使这一测绘得以实现。该合同将涉及这项工作的三个关键目标：利用两项甚低频遥感技术的进步，制定统一的地图确定方法;量化所实现的时间和空间分辨率;通过检查内部自洽性并与外部HF吸收分析结果进行比较来进行验证。将对这些地图进行分析，并将原始和处理后的数据产品公之于众，从而将可能的科学影响扩大到其他领域。该奖项支持的研究将代表在实现对航空业有用的HF吸收准确模型方面取得的进展。作为该奖项更广泛的教育推广活动的一部分，将开发一套教程，使相关领域的科学家能够理解和使用公共数据集，并作为数据公开发布的一部分提供。来自代表性不足的群体的暑期本科实习生将参加这项奖励的研究工作，使用既定的格鲁吉亚技术计划，旨在实现多样性和包容性。VLF信号有效地反映了从这个等离子体区域（称为D-区域），但也VLF信号检测到的距离从源的变化作为电离层条件的变化。虽然这一原理已经被人们了解了几十年，但将测量结果转化为等离子体密度估计值更为困难。有两个主要的甚低频波源可用于这种形式的遥感：甚低频发射机和全球闪电发射的无线电大气（天电）。 两个主要的进展，每一种类型的VLF源，解决了许多这些问题。该奖项的研究计划将合并甚低频发射机和sferics在一个单一的技术。将采用一种新的方法，用独立的测量来验证甚低频遥感结果。这一发展将避免甚低频遥感的一个长期障碍，即缺乏对等离子体含量的直接测量以便与结果进行比较。新的能力不仅可以直接观测周围的电离层条件，包括昼夜和季节变化，还可以观测几种类型的电离层扰动，如早期甚低频事件以及与大气重力和声波有关的影响。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The award to Georgia Tech University would support an initiative to establish a long-term ionospheric plasma spatial mapping capability for the altitudes of 60-90 km with Very Low Frequency (VLF, 3-30 kHz, 33-333 μs period) radio receivers. While spatial maps of the upper atmosphere plasma distribution for altitudes above 250 km have been obtained through remote sensing using GPS measurements of total electron content, no such capability currently exists for this lower ionospheric plasma region. VLF remote sensing has long been viewed as the most promising technique for remote sensing in this region, but several factors have made it very difficult to go from VLF measurements to ionospheric maps. However, two recent advances in ionospheric diagnostics have now enabled this mapping to be achieved. This award would address three key goals for the work: the formulation of a unified map determination method using a fusion of two VLF remote sensing advances, quantification of the temporal and spatial resolution achieved, and validation through checking for internal self-consistency combined with comparison with results of external HF absorption analysis. These maps would be analyzed and the raw and processed data products made public expanding the possible scientific impact to other fields. The research supported by this award would represent progress toward achieving an accurate model of HF absorption useful for the aviation industry. As part of this award broader educational outreach, a set of tutorials that would enable scientists in related fields to understand and use the public datasets would be developed and made available as part of the public release of data. Summer undergraduate interns from underrepresented groups would participate in this award research effort using an established Georgia Tech program designed to achieve diversity and inclusion.VLF signals reflect efficiently from this plasma region (known as the D-region) but also VLF signals detected at a distance from a source change as ionospheric conditions change. While this principle has been known for decades, translating measurements to plasma density estimates is more difficult. There are two major sources of VLF waves that can be used for this form of remote sensing: VLF transmitters and radio atmospherics (sferics) emitted by global lightning. Two major advances, one for each type of VLF source, solve many of these problems. The award research plan would merge VLF transmitters and sferics in a single technique. A novel way of validating VLF remote sensing results with independent measurements would be introduced. This development would avoid a longstanding hurdle for VLF remote sensing, which is the lack of direct measurements of plasma content for comparisons with results. The new capability would allow direct observations of not only the ambient ionospheric conditions including diurnal and seasonal changes, but several types of ionospheric disturbances like Early VLF events and effects relating to atmospheric gravity and acoustic waves.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.