CAREER: Unraveling Polar Electron Energetics

The Earth’s upper atmosphere includes a region of partially ionized gas known as the ionosphere. The magnetosphere, created by Earth’s magnetic field, acts as an obstacle to the solar wind, the stream of charged particles from the Sun. This project seeks to understand the processes heating electrons at polar latitudes using a combination of theory, numerical modeling, and analysis of radar and satellite observations. The processes coupling energy from the solar wind and magnetosphere into the ionosphere are highly complex. Accurately describing electron energetics in ionospheric models remains challenging due to the complex kinetic electron physics involved. A key parameter for understanding the ionosphere and ion escape from the ionosphere is the temperature of electrons. This research program will be combined with educational and public outreach efforts related to teaching about the physics of high-energy electrons in space, including those electrons that create the colors of the northern lights. The energetic electron transport phenomena studied in this project are very closely related to auroral electron transport phenomena. The project will create a “Make Your Own Aurora” website where users can learn about heliophysics by digitally simulating auroral emissions. Students of graduate and undergraduate levels will be involved in this project. This project seeks to understand the physical mechanisms controlling electron energetics in the polar cap ionosphere. The ability to predict ionospheric electron temperatures is of fundamental importance to aeronomy since they affect chemical reaction rates, ambipolar electric fields, plasma scale heights, and ion upflows. Science questions to be addressed are 1) Which physical processes explain the electron temperatures observed in the polar cap ionosphere? 2) How do polar cap electron temperatures vary with solar, geomagnetic, and background plasma conditions? And 3) How do electron temperature variations relate to ion upflow variations? They will perform statistical studies of temperature measurements from the Resolute Bay Incoherent Scatter Radar (RISR), measurements from the Defense Meteorological Satellite Program (DMSP) spacecraft, and energetic electron distributions from the Fast Auroral Snapshot (FAST) spacecraft. The theory and modeling activities will integrate kinetic models of energetic electrons previously developed into the High-latitude Ionospheric Dynamics for Research Applications (HIDRA) model. A computationally efficient version of HIDRA that can reproduce these measured quantities will be a major advance for high latitude modeling. 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.