10:45 AM - 12:15 PM
[PEM12-P04] Statistical studies of plasma structuring in the auroral ionosphere by in-situ measurements
Keywords:swarm, plasma irregularities, particle precipitation
The plasma in the ionosphere is subject to auroral particle precipitation, which is important for the development of irregularities in the plasma density. These irregularities can be broken down from larger to smaller scales which have been linked to strong scintillations in the Global Navigation Satellite System (GNSS) signals. In-situ data from sounding rockets show enhanced electron density fluctuations in regions immediately poleward of the cusp and in regions were no or little particle precipitation was detected.
We use several years of 16 Hz faceplate density measurements, field-aligned current (FAC) and 50 Hz magnetic field data, as well as data from the IPIR dataset from the Swarm mission to do long term statistics in order to investigate the coherencies between particle precipitation and electron density fluctuations. We use the FAC data and the y-component of the magnetic field because of its high sampling frequency as a measure of particle precipitation to connect the formation of density irregularities in the auroral oval and precipitating particles. The data used in this study covers the polar cap, auroral oval and mid-latitudes with an emphasis on high latitudes. We present power spectral densities (PSD) of electron density irregularities and magnetic field data for one-minute intervals, meaning each interval spans roughly 440 km. These PSD were then characterized by the slopes of the power spectra, in particular a steepening of the slope, and the integrated power which is deposited within different frequency intervals in the PSDs.
For the electron density fluctuations, we notice an increase in power and in the occurrence of double slopes within both the auroral oval and polar cap, and especially a strong increase of integrated power for all frequency intervals within the polar cap.
While the PSD for the magnetic field data shows a double slope for all regions, the low frequency slope becomes steeper while the high frequency slope becomes shallower, and the break point shifts to lower frequencies within the auroral oval.
Finally, we go on to discuss the connection between the results from the FAC and magnetic field data, and the structuring of the density at high latitudes.
We use several years of 16 Hz faceplate density measurements, field-aligned current (FAC) and 50 Hz magnetic field data, as well as data from the IPIR dataset from the Swarm mission to do long term statistics in order to investigate the coherencies between particle precipitation and electron density fluctuations. We use the FAC data and the y-component of the magnetic field because of its high sampling frequency as a measure of particle precipitation to connect the formation of density irregularities in the auroral oval and precipitating particles. The data used in this study covers the polar cap, auroral oval and mid-latitudes with an emphasis on high latitudes. We present power spectral densities (PSD) of electron density irregularities and magnetic field data for one-minute intervals, meaning each interval spans roughly 440 km. These PSD were then characterized by the slopes of the power spectra, in particular a steepening of the slope, and the integrated power which is deposited within different frequency intervals in the PSDs.
For the electron density fluctuations, we notice an increase in power and in the occurrence of double slopes within both the auroral oval and polar cap, and especially a strong increase of integrated power for all frequency intervals within the polar cap.
While the PSD for the magnetic field data shows a double slope for all regions, the low frequency slope becomes steeper while the high frequency slope becomes shallower, and the break point shifts to lower frequencies within the auroral oval.
Finally, we go on to discuss the connection between the results from the FAC and magnetic field data, and the structuring of the density at high latitudes.