LAMP Science Questions

  1. What is the optical signature of auroral microburst precipitation and what is its spatial distribution with respect to pulsating aurora?
  2. Does auroral microburst precipitation (specifically microburst “trains”) account for the high frequency modulations typically superimposed on the pulsating aurora, i.e. how are those structures related temporally?
  3. Is there a high energy tail component of the auroral microburst electron distribution with energy greater than a few 100 keV, i.e. are the auroral microbursts that are observed within pulsating aurora a subset of relativistic, radiation belt electron microbursts?

Recent publications and presentations show a growing interest in high frequency modulations within pulsating aurora and the possibility of a common source mechanism for auroral microbursts and pulsating aurora (e.g. Kataoka et al. (2012), Miyoshi et al. (2015), Nishiyama et al. (2014) and Tsurutani et al. (2013)). However, while the phenomenon referred to as auroral microbursts has frequently been observed within aurora, and is likely responsible for the high frequency modulations observed within pulsating aurora (something that we hope to show with LAMP), no effort has been made to demonstrate whether or not these microbursts are a subset of the relativistic microbursts thought to consist primarily of electrons from the Earth’s radiation belts. Similarly, most studies of relativistic, radiation belt microbursts have relied on spacecraft that are not equipped to measure the sub-relativistic electron energy range (< few 100 eV) associated with auroral microbursts. For the first time, LAMP will measure the full spectrum of possible microburst energies from 10s of eV to ~2 MeV. Note that, based on existing literature (see Tsurutani et al. (2013) for a comprehensive review), we fully expect to observe auroral microbursts within pulsating aurora. Therefore, LAMP will determine if and how these microbursts are related to the colocated, simultaneously occurring pulsating aurora and whether or not they indeed contain a relativistic, radiation belt electron component.

Relativistic microbursts have been identified as one of the primary loss mechanisms for radiation belt electrons, perhaps capable of emptying the outer radiation belt of MeV electrons in a single day (O’Brien et al., 2004). Lorentzen et al. (2001) state “Future models of radiation belt source and loss processes need to consider microburst effects in order to understand fully the processes causing changes in relativistic electrons during geomagnetic storms.” But we do not yet know if or how the auroral microbursts and pulsating aurora are related to the higher-energy relativistic microbursts. Understanding the connection between pulsating aurora and microbursts constitutes a fundamental part of our understanding of magnetosphere-ionosphere coupling in Earth’s space environment.