Wind/WAVES Observations of Auroral Kilometric Radiation: Automated Burst Detection and Terrestrial Solar Wind ‐ Magnetosphere Coupling Effects

Abstract

Auroral Kilometric Radiation (AKR) is the strongest terrestrial radio emission, and emanates from the same electron acceleration regions from which particles precipitate into the ionosphere, exciting the aurorae and other phenomena. As such, AKR is a barometer for the state of solar wind ‐ magnetosphere ‐ ionosphere coupling. AKR is anisotropically beamed in a hollow cone from a source region generally found at nightside local times, meaning that a single source region cannot be viewed from all local times in the magnetosphere. In radio data such as dynamic spectra, AKR is frequently observed simultaneously to other radio emissions which can have a similar intensity and frequency range, making it difficult to automatically detect. Building on a previously published pipeline to extract AKR emissions from Wind/WAVES data, in this paper a novel automated AKR burst detection technique is presented and applied to Wind/WAVES data. Over a five year interval, about 5000 AKR bursts are detected with median burst length ranging from about 30 to 60 min. During detected burst windows, higher solar wind velocity is observed, and the interplanetary magnetic field clock angle is observed to tend toward BZ < 0, BY < 0, when compared with the entire statistical interval. Additionally, higher geomagnetic activity is observed during burst windows at polar, high and equatorial latitudes.

A Perspective on Substorm Dynamics Using 10 Years of Auroral Kilometric Radiation Observations From Wind

“…The bottom panel of Figure 2 shows the minimum observed frequency of the AKR burst of Fogg et al. (2022) associated with this substorm, used as a proxy for the average upper altitude bound of the AKR source region.…”

“…Fogg et al. (2022) has recently refined the AKR selection, output by Waters, Jackman et al. (2021), to formulate a list of discrete AKR bursts.…”

A perspective on substorm dynamics using 10 years of Auroral Kilometric Radiation observations from Wind

“…The determination of AKR bursts allows us to quantify spectral features such as the bounding frequencies of the bursts and their spectral extent (Fogg et al, 2022). Such parameters can give us further insight into the altitudinal evolution of the auroral acceleration region during the substorm timeline.…”

“…We now have an opportunity to significantly extend the study of the link between substorms and AKR due to the availability of years of high fidelity data from the Wind spacecraft. Accounting for viewing limitations, 10 years of calibrated AKR observations from 1995 to 2004 are now able to be examined, with properties of the emission itself and spectral features available (Fogg et al, 2022;Waters, Jackman et al, 2021). This allows coincident lists of substorm events, derived from various observational signatures and that also cover decadal timespans, to be compared with the AKR observations.…”

The "SPectrogram Analysis and Cataloguing Environment" (SPACE) Labelling Tool

“…For example, the Cassini mission at Saturn spent 13 years studying the kronian system, revealing several components to its radio spectrum (Lamy et al, 2008;Ye et al, 2011;Lamy, 2017;Taubenschuss et al, 2011). Furthermore, the Wind spacecraft has spent almost two decades observing terrestrial (and solar) radio emissions from a range of vantage points near Earth (Waters et al, 2021;Fogg et al, 2022;Bonnin et al, 2008).…”