The Precipitated Electrons in the Region of Diffuse Aurora Driven by Ionosphere‐Thermosphere Collisional Processes. Issue 16 (16th August 2021)

• Record Type: Journal Article
• Authors: Khazanov, George V.; Glocer, Alex; Chu, Mike
• Is Part Of: Geophysical research letters. Volume 48:Issue 16(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-16
• Subjects: diffuse aurora -- magnetosphere‐ionosphere coupling -- atmospheric collisions; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL094583
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Traditionally, it is widely assumed that the source of electron precipitation in the region of diffuse aurora is wave‐particle interaction processes in the Earth's plasmasheet. It is difficult to imagine that ionosphere‐thermosphere system is also actively involved in the formation of electron precipitation and provides a very noticeable energy contribution to this process. In this study, we use specifically designed simulation scenarios of the SuperThermal Electron Transport code to clearly distinguish between the magnetospheric and ionospheric contributions to the precipitating electrons in the region of diffuse aurora. It is demonstrated that atmospheric collisional processes and the overall magnetosphere‐ionosphere‐atmosphere energy circulation dynamics, with the participation of two magnetically conjugate hemispheres, play a very important role in the formation of electron energy fluxes that are coming from the magnetosphere. Plain Language Summary: It is widely agreed that the electrons originating in space are primarily responsible for the initiation of the beautiful light displays of aurora in the sky. This is definitely true, because the ignition of polar lights is driven by the different acceleration processes in near‐Earth space. These processes, however, do not provide the total amount of energy coming into the polar ionosphere‐thermosphere system carried by precipitating auroral electrons. As we find and explain in this letter, the atmosphere by itself, provides an additional and very noticeable amount of energy to the electrons driving the aurora. This energy is drawn from a reservoir built up by the interaction of electrons with magnetically connected portions of the atmosphere, which traps and redistributes the incoming energy. The result is that more energy can appear to be carried by precipitating electrons than is provided instantaneously by the acceleration processes in space. This substantial additional energy is only possible because of the interaction with the atmosphere. We demonstrate this phenomena using carefully designed numerical simulations. Key Points: Electron precipitation dynamics in the region of diffuse aurora Distinguishing between electrons of magnetospheric and ionospheric origins using SuperThermal Electron Transport code simulation scenarios The quantitative assessment of the role of atmospheric collisions in electron precipitation phenomena in diffuse aurora