Collaborative Research: CEDAR: Searching for the Strongest Thermospheric Wind and Highest Temperature inside Strong Thermal Emission Velocity Enhancements

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Auroras are a spectacular display of the effects of Sun's energetic particles raining down and colliding with Earth’s atmosphere at high latitudes. These colorful displays are widely observed to have several typical shapes and colors. Recently, a ‘new’ type of aurora-like light at high latitudes has been observed. It often consists of a narrow purple arc with narrow green ‘picket-fence’ features. Its distinct shapes and colors are different from typical auroras. Scientists named it as STEVE (Strong Thermal Emission Velocity Enhancement). Because STEVE occurs at lower latitudes than typical auroras (called sub-auroral region), it is believed to be associated with a strong flow of charged particles in the ionosphere, a layer above our atmosphere with free-flowing ions and electrons. Research on STEVE will help us understand the interactions between the high and low latitude ionosphere and how solar energy impacts the entire Earth’s atmosphere system and space weather.As its name suggested, STEVE is interpreted to be due to the chemiluminescent reactions induced by heat generated by strong ion neutral interaction at large ion drift (~ 5000 m/s). To test the hypothesis of heat from strong ion-neutral interaction causing STEVE, both ion drift and thermospheric wind observations are necessary. The Swarm satellites have provided ion drift data in STEVE studies, but observations are missing for the thermospheric wind and temperature observations in the sub-auroral region. To obtain thermospheric temperature and wind observations for ascertaining the STEVE emission mechanism, this project will deploy a Fabry Perot Interferometer (FPI) at Athabasca University (54.60N, 113.64W, 61 MLAT), where an optical observatory is located and STEVE had been observed. In addition, a small color CCD all sky camera will be used to monitor the occurrence of STEVE and auroral activities and a dual-band GPS receiver will be used to monitor ionospheric Total Electron Content variations. The team plans to spend 20 nights/year to take all sky camera images in real time and steer the FPI sky scanner toward the STEVE when it is sighted. The real time monitoring is planned for substorm events following future solar active region events, which will be tracked from NOAA space weather services. The auroral images and FPI data will be studied in combination with the Swarm ion drift data to achieve a comparatively complete diagnosis of the ionosphere and thermosphere conditions. The project will address three topics: 1) Thermospheric conditions associated with STEVE and their effect on its emission; 2) SAPS effects on thermospheric winds; 3) Thermospheric wind's effect on the expansion of the substorm negative phase. Given the extreme ionospheric condition associated with STEVE, large thermospheric wind speed and high neutral temperature could be observed, which can change our perception of thermosphere-ionosphere interactions. The proposed Athabasca FPI can bridge the large spatial gap between the Resolute and Boulder FPI and allow the substorm effect from high to mid latitudes to be tracked. Since Athabasca is located at a latitude range that is strongly affected by the substorm negative phase, the results of this project will directly address a major concern for space weather forecast.Since STEVE was first observed by citizen scientists, this project will generate a greater public awareness of the aeronomy research and will stimulate future public engagement with science and technology. The project will foster diverse collaborations and establish a partnership between NCAR and a scientifically competitive institution in an EPSCoR state. The proposing team would make this project an opportunity to promote STEM education, increase the participation of women and underrepresented minorities in STEM.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.