Merging of Observations and Models for the Earth's Schumann Resonances

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。全球电路的定量测量对于地球-大气系统的基本描述以及作为全球气候变化的替代测量都很重要，其中闪电起着关键作用。测量全球电活动的一个关键手段是通过所谓的舒曼共振（SR），这是一种极低频（ELF）电磁波，通过由地球表面和电离层构成的天然“波导”，在长（~半球尺度）距离上传输。该项目支持的工作将维护一个关键的极低频信号检测站（位于罗德岛州），并允许访问和全面分析来自全球极低频网络的校准数字观测数据。该分析将利用AMMA（非洲季风多学科分析）项目期间对非洲强对流系统的专门短时间观测，并受益于最近对电离层行为昼夜差异相关的SR传播不对称性的改进。虽然先前基于单站ELF数据的分析已经取得了丰硕的成果，但本研究中来自全球多个站点的数据整合有望超越以往的结果。这项研究的智力价值在于我们提高了监测和理解下层电离层结构及其由闪电调制的能力，以及通过扩展确定植根于对流层气象学的上层大气影响的能力。这项工作将通过对本科生的教育产生更广泛的影响，他们将直接参与罗德岛ELF接收器的维护以及对收集到的数据的分析。这些数据将与在全球网络中维持其他极低频气象站的国际合作者共享，以便利对准确性的交叉核查和比其他方法更全面的分析。这项工作还将为在不断演变的气候系统中对大气对流（如雷暴）活动的数量/强度的全球趋势进行高度综合、独立的测量提供手段。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Quantitative measurements of the global electric circuit, in which lightning plays a key role, are important both in terms of basic description of the earth-atmosphere system and as a proxy measure for changes in global climate. One key means through which global electrical activity may be measured is through so-called Schumann Resonances (SR), which are extremely low frequency (ELF) electromagnetic waves channeled over long (~hemispheric-scale) distances through a natural "waveguide" constituted by the earth's surface and the ionosphere. Work supported under this project will both maintain a key ELF signal detection station (located in Rhode Island) and allow access to and comprehensive analysis of calibrated digital observations from a worldwide ELF network over extended time periods. This analysis will take advantage of specialized shorter-duration observations of intense convective systems over Africa, as obtained during the AMMA (the African Monsoon Multidisciplinary Analyses) project, as well as benefitting from recent improved knowledge of the asymmetry in SR propagation associated with day-night differences in ionospheric behavior. While prior analyses resting on single-station ELF data have been fruitful, the integration of data from multiple stations around the globe in this study promises to surpass previous results.The intellectual merit of this research rests in our improved ability to both monitor and understand the structure of the lower ionosphere and its modulation by lightning, and by extension determination of upper-atmospheric influences rooted in the meteorology of the troposphere. This effort will have broader impacts through the education of undergraduate students, who will be directly involved in maintenance of the Rhode Island ELF receiver as well as analysis of data so-collected. These data will be shared with international collaborators maintaining other ELF stations in the global network to facilitate cross-checking of accuracy and more comprehensive analyses than would otherwise be possible. This work will also provide means for a highly integrated, independent measure of global trends in the amount/intensity of atmospheric convective (e.g. thunderstorm) activity within the evolving climate system.