Why Atmospheric Backscatter Is Important in the Formation of Electron Precipitation in the Diffuse Aurora

Abstract

Magnetic storms and substorms result from a complex interaction of the solar wind with the Earth's magnetosphere. They reconfigure the near-Earth geospace environment and cause major increases in energetic particle precipitation in the auroral zone, making them an important component of space weather. The average integrated number flux of the precipitating auroral ions is typically 1 to 2 orders of magnitude less than that of the precipitating auroral electrons (Hardy et al., 1989) and precipitation of <∼30 keV electrons accounts for ∼80% of auroral energy into the ionosphere (Newell et al., 2009). Therefore, the flux formation of precipitating electrons is the focus in this paper.There are three main auroral electron precipitation mechanisms: wave scattering of plasma sheet electrons into the loss cone; sometimes called diffuse aurora, acceleration by interactions with Alfvén waves; broadband or Alfvén aurora, and acceleration due to a quasi-static parallel electric field; monoenergetic or discrete aurora. Distributions of diffuse auroral electron fluxes precipitating downward into the ionosphere are often well represented by Maxwellian, kappa or Gaussian distributions (e.g.

Thermal Electron Heat Fluxes Associated With Precipitated Auroral Electrons During the Saint Patrick's Days 2013 and 2015 Geomagnetic Storms

“…As it was discussed by Khazanov and Chen (2021), and briefly demonstrated in Section 3.4, multiple backscatter phenomena is one of the key and unique element of the STET code that dramatically redistribute initial high energy electron precipitation that is coming from the magnetospheric source (Step 1 in Figure 2) and makes a very noticeable change in the electron energy fluxes entering ionospheric altitudes (Khazanov, Chen, et al, 2019;Khazanov, Sibeck, & Chu, 2021). The STET model has been validated with DMSP (Khazanov, Glocer, & Chu, 2021;Wing et al, 2019) and FAST (Khazanov et al, 2016) electron spectra measurements as well with optical observation by Samara et al (2017) and is believed to be reliable in the studies of electron thermal flux formation at ionospheric altitudes .…”

“…This paper investigates the heat flux formation associated with diffuse auroral precipitating electrons in the high latitude ionosphere on a global scale during the St. Patrick's Days 2013 and 2015 geomagnetic storms. To do this we couple the magnetically and electrically self-consistent Rice Convection Model-Equilibrium (RCM-E; Chen et al, 2012Chen et al, , 2019Lemon et al, 2004) with STET as described by Khazanov, Chen, et al (2019), and further discussed by Khazanov and Chen (2021) in the application to the region of diffuse aurora. The precipitating auroral electrons with energies above ∼100 eV that are initially driven by wave-particle interactions (WPIs) in the magnetosphere in the RCM-E are referred in this paper as "precipitating electron fluxes".…”

Validation of SSUSI-derived auroral electron densities: comparisons to EISCAT data

“…That study also contains an extensive review about the conversion of the SSUSI FUV data to the precipitating electron characteristics. In a follow-up study, Knight (2021) also investigated the contribution of proton precipitation to the auroral emissions, finding a lower impact of protons than expected.…”

The Space and Terrestrial Weather Variations as Possible Factors for Ischemia Events in Saint Petersburg

“…The mutual connections of the environmental processes are well-known. They have been carefully investigated in the past and are under investigation now [31][32][33][34][35][36][37][38][39][40][41][42]. It is well-known that the particle fluxes behavior in the inter-planet space, and particularly in Earth's vicinity, named the near-Earth space or Geospace [31,32] in the radiation belts, is governed by solar wind [31].…”

“…Additionally, the atmosphere is involved into these interactions. The atmosphere part in these processes has been investigated now for a long time from two sides-(1) the atmosphere processes as a factor for the electron precipitation [36] in the sub-auroral polarization stream (SAPS) [35] and (2) the atmosphere as the object undergoes Space Weather impact [37][38][39]. The concrete response of the Earth's atmosphere to the above-mentioned impact is shown by different research from the different points: the troposphere changes [40], thermosphere processes [41], and the polar vortex form changing [42].…”