Outstanding Questions on Auroral Radiation Fine Structure

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This proposal is funded to continue study of plasma waves and radiation that play key roles in controlling the charged particle transport, loss rates, and energy exchange in the Earth's magnetosphere. These waves also directly or remotely sense space plasma processes, structures, and boundaries that interact with the solar wind plasma flow. Operating a digital radio receiver (100 KHz -5 MHz) at the South Pole station in the Antarctic will answer some outstanding questions regarding the fine structure of above radio emission: What is the relationship between the recently discovered fine structures of low frequency (LF) auroral hiss and middle-frequency (MF) burst: two types of radio emissions that occur together at the onset of the auroral substorm? Are the LF auroral hiss and auroral MF burst correlated or anti-correlated temporally and spatially on sub-second time scales? Are structured "AKR-like" emissions at 150-750 kHz, which superficially resemble the Auroral Kilometric Radiation (AKR), evidence of transmission of AKR to ground level? Preliminary comparisons between South Pole radio data and corresponding data from the Geotail satellite deep in the Earth's magnetotail suggest a good correlation between AKR and the ground-level "AKR-like" events, which if confirmed will support previously ignored theories of mode conversion and downward propagation of AKR. The proposed experiments must be performed in the Antarctic, because critical portions of the LF/MF radio environment are impossible to observe at Northern Hemisphere locations due to man-made electromagnetic interference. This proposal will provide education and training to both the undergraduate and graduate students at Dartmouth College, forming the major part of a PhD dissertation. It will also provide the basis for multiple undergraduate internships. Researchers at Dartmouth College will participate in public outreach as a part of this work, including public talks or visits to schools.