Duration of Individual Relativistic Electron Microbursts: A Probe Into Their Scattering Mechanism. Issue 17 (2nd September 2021) - Shumko, M.
Abstract: We used the Solar Anomalous and Magnetospheric Particle Explorer to identify and quantify the duration of relativistic, > 1 MeV, electron microbursts. A typical relativistic microburst has a ≈ 100 millisecond (ms) duration, and the interquartile range of the duration distribution is 70–140 ms. We investigated trends in the microburst duration as a function of geomagnetic activity, L‐shell, and magnetic local time (MLT). The clearest trend is in MLT: the median microburst duration doubles from 75 milliseconds at midnight to 140 milliseconds noon MLT. This trend is similar to the whistler mode chorus rising tone element duration trend, suggesting a possible relationship. Plain Language Summary: Energetic electron microbursts are an intense form of naturally occurring particle precipitation from the outer Van Allen Radiation Belt into Earth's atmosphere. Microbursts are observed in, or just above, the Earth's atmosphere, and are characterized by their short duration in time series data, often defined to be less than a second. The impact of microburst precipitation on the Earth's atmosphere is uncertain, but has been predicted to substantially degrade mesospheric ozone through the production of odd nitrogen and odd hydrogen molecules. Besides their environmental impact, we don't comprehensively understand how plasma waves, such as whistler mode chorus waves, scatter microbursts into our atmosphere. Therefore, in this study we quantified the duration of microbursts and used it as a proxy to understand how microbursts are scattered by these waves. We found that the microburst and chorus wave durations are correlated: their duration roughly doubles between the anti‐sunward and sunward regions of the outer radiation belt. Key Points: We identified relativistic microbursts observed by the Solar Anomalous and Magnetospheric Particle Explorer satellite and quantified their duration The microburst duration interquartile range is 70–140 ms and shows trends in Auroral Electrojet, L‐shell, and magnetic local time (MLT) In MLT, microburst durations double between midnight and noon‐a trend similar to chorus element durations