Statistics of LF-MF Auroral Radio Emissions Observed at South Pole Station in 2020

In 2022–2023, Dartmouth College in collaboration with University of New Brunswick set up receiving systems to measure natural auroral radio emissions at three sites in Nunavut, Canada: Qikiktarjuaq, Iqaluit, and Halls Beach. These sites surround the point which is geomagnetically conjugate to South Pole Station, Antarctica, where a similar radio recieving system operates. Multiple examples have bee recorded of simultaneous radio emissions at South Pole Station and one of the northern hemisphere sites, including both LF auroral hiss and 2fce and 3fce cyclotron harmonic emissions. About half of the conjugate LF auroral hiss events occurred within one month of equinox. In two examples near solstices, the hiss in the sunlit hemisphere is much weaker than that in the dark hemisphere. In about half of the examples, the LF hiss initiates at the same time in the two hemispheres to within 10 seconds. In most of the other cases, hiss occurs first in one hemisphere or the other by 100–200 seconds. The initial data show no obvious relationship between IMF conditions and simultaneity or lack thereof of the LF hiss in the two hemispheres. Near equinox multiple examples of simultaneous 2fce cyclotron harmonic emissions have been recorded, but away from equinox conditions, observation of 2fce in the dark hemisphere simultaneous with 3fce in the daylit hemisphere is more common, as expected because the higher density in the daylit hemisphere favors emission of higher harmonics. A surprising result of these observations is that on occasion the structure and frequency dispersion of the cyclotron harmonic emissions in the two hemispheres are similar, suggesting that local conditions may not be as dominant in determining the fine structure of the emissions as previously thought.