Mesospheric ozone destruction by high‐energy electron precipitation associated with pulsating aurora

Abstract

Energetic particle precipitation into the upper atmosphere creates excess amounts of odd nitrogen and odd hydrogen. These destroy mesospheric and upper stratospheric ozone in catalytic reaction chains, either in situ at the altitude of the energy deposition or indirectly due to transport to other altitudes and latitudes. Recent statistical analysis of satellite data on mesospheric ozone reveals that the variations during energetic electron precipitation from Earth's radiation belts can be tens of percent. Here we report model calculations of ozone destruction due to a single event of pulsating aurora early in the morning on 17 November 2012. The presence of high‐energy component in the precipitating electron flux (>200 keV) was detected as ionization down to 68 km altitude, by the VHF incoherent scatter radar of European Incoherent Scatter (EISCAT) Scientific Association (EISCAT VHF) in Tromsø, Norway. Observations by the Van Allen Probes satellite B showed the occurrence of rising tone lower band chorus waves, which cause the precipitation. We model the effect of high‐energy electron precipitation on ozone concentration using a detailed coupled ion and neutral chemistry model. Due to a 30 min, recorded electron precipitation event we find 14% odd oxygen depletion at 75 km altitude. The uncertainty of the higher‐energy electron fluxes leads to different possible energy deposition estimates during the pulsating aurora event. We find depletion of odd oxygen by several tens of percent, depending on the precipitation characteristics used in modeling. The effect is notably maximized at the sunset time following the occurrence of the precipitation.

Northern Hemisphere Stratospheric Ozone Depletion Caused by Solar Proton Events: The Role of the Polar Vortex

“…Turunen et al, 2016). Results indicate that SPEs are linked to an~5-10% decrease in ozone at~20 km altitude.…”

On the Effects of Bremsstrahlung Radiation During Energetic Electron Precipitation

“…The largest enhancement of NO x concentration is approximately a factor of 8.3 and occurs around 72 km. After the electron forcing, the NO x recovery is mainly due to the photodestruction of NO, which is gradual and relatively slow (Turunen et al, ). About 71% of the excess NO x produced by the forcing of 10 MeV monoenergetic electrons at ∼72 km remains beyond the end of the 2 day simulation period (see Figure ).…”

Observation of pulsating aurora signatures in cosmic noise absorption data

“…CNA values typically exceed 0.5 dB during energetic particle precipitation and may occasionally reach values as high as 10 dB. However, the pulsating aurora events studied by Milan et al [] and recently Turunen et al [] exhibit CNA of the order of 0.5–1 dB.…”

“…In particular, conjunctions between the Japanese Arase (ERG) satellite [ Miyoshi et al , ] and ground‐based instruments in northern Fennoscandia in the postmidnight and morning magnetic local time sectors could be exploited to study pulsating aurora even outside of the dark season, using KAIRA instead of the optical instruments. This may prove important to study the atmospheric effects of high‐energy precipitation during pulsating aurora events, as was initiated by Turunen et al [].…”