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.
