Collaborative Research: CEDAR: Why is the High-Latitude Ionosphere More Variable in January than in July?

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With humanity continuing to explore last frontiers of the new Arctic and Antarctic, polar nations invest heavily in improving navigation satellite coverage of this region. In this context, the ionized portion of the upper atmosphere (ionosphere) at polar latitudes represents an important piece of the puzzle, since it is the medium through which the satellite radio signal travels and since it is known to contain strong disturbances. This award provides support for a comprehensive investigation into unexpected plasma density enhancements at polar latitudes called sporadic-F. The focus of the investigation is on the Global Navigation Satellite System (GNSS) observations of sporadic-F. Navigation satellites often experience degradation of radio signal quality and sporadic F has been demonstrated to be one of the leading causes. Opening of Arctic to shipping traffic as the ice cap melts and an ever-increasing number of transpolar flights make this investigation particularly timely due to its potential to characterize occurrence and identify mechanisms for GNSS signal loss. This investigation will validate a recent set of satellite observations that fly in the face of conventional wisdom and past expectations based on decades of northern hemisphere data analysis. The validation will utilize ground-based observations in both hemispheres and first-principles modeling. It is well-known that sporadic-F is controlled by magnetospheric forcings (convection and precipitation), and it has been hypothesized that thermospheric variations may also be important. Therefore, new insights into the characteristics of those systems (magnetosphere and thermosphere) are expected. To aid in mapping and understanding dynamic high-latitude plasma flows, the state-of-the-art Lagrangian coherent structure analysis code will be used and developed. This work has the potential to transform the understanding of a phenomenon that has been the subject of extensive study since its discovery.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.