Perturbations in ionospheric total electron content (dtec) with timescales of ~10S-1000S can be driven from above by processes in the magnetosphere - including magnetospheric ultra low frequency (ULF)…

The Space Science Institute, a non-profit research organization based in Boulder, Colorado, was awarded a $401,525 research grant by a civilian federal agency (via the Shared Services Center) on September 1, 2021, with a completion deadline of August 31, 2026. This grant supports a comprehensive statistical and numerical investigation into how magnetospheric ultra-low frequency (ULF) waves drive perturbations in ionospheric total electron content (TEC), a critical space weather phenomenon. The research addresses a significant gap in current knowledge by moving beyond single-event case studies to establish how frequently extreme TEC perturbations occur, their geographic distribution, and the driving conditions that produce them. The study will employ realistic numerical simulations incorporating ionosphere-thermosphere coupling to determine whether ULF waves routinely produce space-weather-significant TEC perturbations and to identify the distinguishing characteristics of such perturbations.

The research directly supports NASA's space weather monitoring and prediction capabilities by clarifying the mechanisms through which magnetospheric processes affect ionospheric conductivity, heating rates, and geomagnetically induced currents—all critical factors for protecting critical infrastructure and communication systems. By quantifying the relationship between magnetospheric dynamics and ionospheric response, this work will enhance the scientific foundation for space weather hazard assessment and improve understanding of how multiple physical mechanisms may simultaneously contribute to TEC variations. The award was made on a competitive, non-set-aside basis, reflecting the Space Science Institute's established technical merit in conducting advanced space physics research for federal agencies.

Perturbations in ionospheric total electron content (dtec) with timescales of ~10S-1000S can be driven from above by processes in the magnetosphere - including magnetospheric ultra low frequency (ULF) waves - and below by processes such as earthquakes that couple to acoustic-gravity waves in the atmosphere. Characterizing the subset of dtec related to ULF waves is of high priority as several studies have shown these perturbations impact ionospheric space weather. For example, case studies have shown that ULF waves can produce extreme dtec, in some cases leading to a modulation of height-integrated ionospheric conductances by a factor of 7 to 10. These extreme perturbations can in turn affect ionosphere/thermosphere heating rates, coupling to geomagnetic perturbations that affect geomagnetically induced currents (GIC), and scintillation these are all space weather hazards. However, since most work has focused on single event studies, we have limited information on how often these extreme dtec events occur and their favored locations and driving conditions. In the absence of a comprehensive statistical study, IT is currently unknown whether ULF waves routinely drive dtec of significance for space weather. Moreover, past work has demonstrated multiple mechanisms to generate dtec however, due to a lack of realistic numerical simulations that capture ionosphere-thermosphere (i-t) coupling, there is limited information regarding (1) how multiple mechanisms may contribute simultaneously to the dtec and (2) how ionosphere thermosphere coupling affects the TEC response. The proposed study will make progress on these challenges by addressing the over-arching question, "are space-weather significant ULF TEC perturbations routinely driven by magnetospheric waves?", and sub-questions "what are the distinguishing features of TEC perturbations driven by magnetospheric ULF waves?" and "what are the favored mechanisms/conditions to drive TEC perturbations of significance for space weather?" we will address these questions using (1) a statistical study of multi-point TEC, ground magnetometer measurements and NASA satellite observations, combined with volcano/earthquake lists, (2) numerical experiments using global ionosphere thermosphere model (gitm) driven by ULF electric field perturbations with different temporal and spatial scales (constrained by previous observations), and (3) data-model comparisons during detailed case studies with constraints on the source of magnetospheric ULF wave activity, ionospheric electric fields, and multi-point TEC observations. The proposed work is relevant to the HSR program because a) IT includes numerical simulation (gitm), (b) IT includes data analysis and interpretation of NASA-spacecraft observations, and (c) IT is relevant to the heliophysics program overarching goal to "to understand the sun and its interactions with the earth and the solar system, including space weather" because we will make progress in understanding the role of ULF waves in driving TEC perturbations with large amplitudes, which affect ionospheric conductivity and cause space weather impacts (see above). There is a high potential impact for this project because we are addressing unresolved questions with new tools and approaches: (1) we will perform a statistical study with satellite conjunctions whereas most past work focused on event studies/small intervals (2) we will consider driving from the magnetosphere and the surface/lower atmosphere in the same investigation, (3) we will use 1-s and 5-s TEC measurements instead of more widely available 30-s measurements that cannot adequately sample significant parts of the ULF range. This investigation is also timely with advanced i-t modeling capabilities not available before that are crucial to capture spatially localized ULF waves and surface disturbances.