The Role of Ion Demagnetization Altitude in MIT Energy Transfer

Ion-neutral coupling is critical to understanding energy transfer between the magnetosphere and ionosphere. Ion demagnetization represents the transition of ion dynamics from electromagnetic forcing toward forcing that is dominated by the thermosphere. Investigations into the altitude profile of this demagnetization process is important for understanding energy exchange in the E region. One relatively unexplored regime is understanding the demagnetization process during particularly strong geomagnetic activity; this regime is particularly challenging due to rapid spatial and temporal variations.

We present results of the ion demagnetization altitude using observations from two previous sounding rocket campaigns launched from the Poker Flat Research Range with suitable instrumentation to investigate ion-neutral coupling in the ionosphere. These two investigations span a range of geomagnetic activity levels and we compare past observations during the JOULE II sounding rocket mission with more recent observations from the JETS sounding rocket mission, launched in 2017. We additionally use the Poker Flat Incoherent Scatter Radar (PFISR) and ground-based magnetometers to provide context information associated with these events. Altitude resolved neutral wind profiles are determined from TMA observations that are triangulated utilizing the line of sight projection method to produce neutral velocity profiles between 80-130 km. In addition to the calculation of the ion demagnetization altitude during these campaigns using the aforementioned data products, a subsequent formulation of this altitude utilizing ion temperature profiles derived using PFISR observations. The difficulty in obtaining reliable neutral wind profiles requires the careful selection of case studies limited to sounding rocket campaigns with triangulated TMA profiles; this difficulty may be avoided by utilizing temperature profiles of charged species combined with modeled neutral temperature profiles from NRLMSIS-2.0.