2025 Workshop: HILAT-GAP

Understanding high-latitude thermosphere dynamics is crucial for unraveling the complex role space weather has on the neutral atmosphere. Because the high-latitude thermosphere is coupled to the magnetosphere-ionosphere system via ion-neutral collisions, the neutral atmosphere experiences highly dynamic forcing during periods of elevated geomagnetic activity. This forcing, which leads to increased Joule heating and ion-neutral collisions, can rapidly alter neutral density, composition, temperature, and winds globally. These changes can lead to increased satellite drag, putting LEO satellites at risk of de-orbiting. The high-latitude thermosphere is uniquely positioned on the boundary of GEM and CEDAR, and its dynamics have impacts on research topics of both communities. For instance, high-latitude neutral winds can significantly change ionospheric currents, altering ground magnetic disturbances and resulting induced currents. The Joule heating rate, which can impact the initiation of traveling atmospheric and ionospheric disturbances (TADs/TIDs) into mid- and low-latitudes also depends on high-latitude neutral winds. Moreover, the thermospheric composition change can lead to significant changes in the magnetosphere-ionosphere-thermosphere system. Therefore, it is crucial to bring together the efforts of both GEM and CEDAR to highlight the current status of the field, identify open science questions, and discuss how to overcome obstacles in methodologies.

Previous research efforts of the high-latitude thermospheric dynamics have been limited due to a lack of global and continuous observations. Additionally, modeling efforts have difficulty characterizing the meso-scale high-latitude thermospheric dynamics due to their focus on resolving global, larger scale phenomena. However, several upcoming missions will provide much needed thermosphere and ionosphere measurements in order to address the open science questions. In addition to the upcoming GDC satellite mission, which will provide in-situ observations of the thermosphere, GDC-Ground will add 6 new Fabry-Perot Interferometers (FPIs) across North America. A new SDI array is also being installed in Scandinavia, which will provide three-dimensional measurements of the neutral wind inside a mutual volume with the EISCAT-3D measurements. These upcoming measurements can additionally be combined with modeling efforts to create a complete picture of high-latitude thermosphere dynamics.

This workshop will focus on studies of high-latitude thermosphere dynamics, including winds, composition, density and temperature, and their impacts on the MIT system during geomagnetically enhanced periods from both modeling and observational fronts. Scene setting talks will be utilized to introduce high-latitude thermosphere dynamics and their drivers. These dynamics will also be discussed in the context of GEM and CEDAR science objectives to establish a common ground between both communities. These talks will be followed by roundtable discussions. Through these roundtable discussions, the workshop aims to produce a comprehensive list of open science questions that can be addressed with the upcoming thermospheric measurements. Roundtable discussion will also address what additional measurements or model improvements are still needed. Finally, roundtable discussions will address how to build a more permanent collaboration between the GEM and CEDAR communities, including proposing a challenge event to combine the efforts of both communities in tackling the open science questions.