Empirical Selection of Auroral Kilometric Radiation During a Multipoint Remote Observation With Wind and Cassini

Abstract

Auroral kilometric radiation (AKR) describes amplified radio emission from the Earth that is generated from relativistic, precipitating electrons along magnetic field lines in the auroral zone and resonates at the electron cyclotron frequency (Wu & Lee, 1979). The emission frequency of an AKR source is close to the local electron gyrofrequency, so that lower frequency AKR emanates from a higher altitude along a field line. AKR is emitted between   30 800 E kHz and has been observed by many Earth-orbiting spacecraft such as Polar, Geotail, and Cluster (e.g.,

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

“…A recently developed technique by Waters, Jackman, et al. (2021) is utilized to extract AKR emission from amongst this complex superposition of radio phenomena. Each frequency‐time bin presented in the spectrogram in Figure 2a is sampled several times within the approximately three minute sweep window.…”

“…Combining both the burst start and end time detection, and the lower and upper frequency limits, the remaining selected data is presented in panel 2(e). In this complex interval, AKR emission has been initially selected from amongst other radio emissions (including a solar type III around 0900 UT) using the Waters, Jackman, et al (2021) empirical selection technique. By exploiting the fact that the AKR emission is distinct in frequency-time space from other sparse emission, the number of filled frequency bins has been used to select the start and end time of the burst.…”

“…1. L2 Wind/WAVES data is processed using Waters, Jackman, et al (2021) selection technique: an empirical threshold is applied to the standard deviation of multiple samplings of each frequency-time bin. 2.…”

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).…”

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

“…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.…”