Contribution of proton and electron precipitation to the observed electron concentration in October–November 2003 and September 2005

Abstract. Understanding the altitude distribution of particle precipitation forcing is vital for the assessment of its atmospheric and climate impacts. However, the proportion of electron and proton forcing around the mesopause region during solar proton events is not always clear due to uncertainties in satellite-based flux observations. Here we use electron concentration observations of the European Incoherent Scatter Scientific Association (EISCAT) incoherent scatter radars located at Tromsø (69.58° N, 19.23° E) to investigate the contribution of proton and electron precipitation to the changes taking place during two solar proton events. The EISCAT measurements are compared to the results from the Sodankylä Ion and Neutral Chemistry Model (SIC). The proton ionization rates are calculated by two different methods – a simple energy deposition calculation and the Atmospheric Ionization Model Osnabrück (AIMOS v1.2), the latter providing also the electron ionization rates. Our results show that in general the combination of AIMOS and SIC is able to reproduce the observed electron concentration within ± 50% when both electron and proton forcing is included. Electron contribution is dominant above 90 km, and can contribute significantly also in the upper mesosphere especially during low or moderate proton forcing. In the case of strong proton forcing, the AIMOS electron ionization rates seem to suffer from proton contamination of satellite-based flux data. This leads to overestimation of modelled electron concentrations by up to 90% between 75–90 km and up to 100–150% at 70–75 km. Above 90 km, the model bias varies significantly between the events. Although we cannot completely rule out EISCAT data issues, the difference is most likely a result of the spatio-temporal fine structure of electron precipitation during individual events that cannot be fully captured by sparse in situ flux (point) measurements, nor by the statistical AIMOS model which is based upon these observations.

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The high latitude D-region and mesosphere revealed by the EISCAT incoherent scatter radars during solar proton events

Advances in Space Research ◽

10.1016/0273-1177(95)00844-5 ◽

1996 ◽

Vol 18 (3) ◽

pp. 83-92 ◽

Cited By ~ 1

Author(s):

P.N. Collis

Keyword(s):

High Latitude ◽

Solar Proton ◽

Incoherent Scatter ◽

Incoherent Scatter Radars ◽

D Region ◽

Solar Proton Events

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Observations of atmospheric dynamics in the low- and middle-mesosphere with the EISCAT incoherent scatter radar during solar proton events

Advances in Space Research ◽

10.1016/0273-1177(92)90447-6 ◽

1992 ◽

Vol 12 (10) ◽

pp. 81-84 ◽

Cited By ~ 3

Author(s):

M.T. Rietveld ◽

P.N. Collis ◽

J. Röttger

Keyword(s):

Solar Proton ◽

Atmospheric Dynamics ◽

Incoherent Scatter Radar ◽

Incoherent Scatter ◽

Scatter Radar ◽

Solar Proton Events

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The effect of Forbush decreases on the polar-night HOx concentration

10.5194/egusphere-egu21-7498 ◽

2021 ◽

Author(s):

Irina Mironova

Keyword(s):

Forbush Decrease ◽

Cosmic Ray ◽

Solar Proton ◽

Polar Night ◽

Forbush Decreases ◽

Ozone Loss ◽

Solar Proton Events ◽

Hydrogen Oxide ◽

The Impact ◽

Ionization Rates

<div> <div> <div> <p>It is well-known that energetic particle precipitations during solar proton events increase ionization rates in the middle atmosphere enhancing the production of hydrogen oxide radicals (HOx) involved in the catalytic ozone destruction cycle. There are many studies where the contribution of energetic particles to the formation of hydrogen oxide radicals and ozone loss has been widely investigated. However, until now, there was no solid evidence that the reduction in galactic cosmic ray fluxes during a magnetic storm, known as Forbush-effect, directly and noticeably affects the polar-night stratospheric chemistry.<br>Here, the impact of the Forbush decrease on the behaviour of hydrogen oxide radicals was explored using the chemistry-climate model SOCOL.<br>We found that hydrogen oxide radical lost about half of its concentration over the polar boreal night stratosphere owing to a reduction in ionization rates caused by Forbush decreases after solar proton events occurred on 17 and 20 of January 2005. A robust response in ozone was not found. There is not any statistically significant response in (NOx) on Forbush decrease events as well as over summertime in the southern polar region.<br>The results of this study can be used to increase the veracity of ozone loss estimation if stronger Forbush events can have a place.</p> <p>Reference: Mironova I, Karagodin-Doyennel A and Rozanov E (2021) , The effect of Forbush decreases on the polar-night HOx concentration affecting stratospheric ozone. Front. Earth Sci. 8:618583. doi: 10.3389/feart.2020.618583</p> <p>https://www.frontiersin.org/articles/10.3389/feart.2020.618583/full</p> <p>The study was supported by the Russian Science Foundation grant (RSF project No. 20-67-46016).</p> </div> </div> </div>

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EISCAT and ESRAD radars observations of polar mesosphere winter echoes during solar proton events on 11–12 November 2004

Annales Geophysicae ◽

10.5194/angeo-31-1177-2013 ◽

2013 ◽

Vol 31 (7) ◽

pp. 1177-1190 ◽

Cited By ~ 1

Author(s):

E. Belova ◽

S. Kirkwood ◽

T. Sergienko

Keyword(s):

Power Spectrum ◽

Electron Gas ◽

Spectral Width ◽

Solar Proton ◽

Solar Proton Event ◽

Complete Theory ◽

Proton Event ◽

Maximum Volume ◽

Incoherent Scatter ◽

Solar Proton Events

Abstract. Polar mesosphere winter echoes (PMWE) were detected by two radars, ESRAD at 52 MHz located near Kiruna, Sweden, and EISCAT at 224 MHz located near Tromsø, Norway, during the strong solar proton event on 11–12 November 2004. PMWE maximum volume reflectivity was estimated to be 3 × 10−15 m−1 for ESRAD and 2 × 10−18 m−1 for EISCAT. It was found that the shape of the echo power spectrum is close to Gaussian inside the PMWE layers, and outside of them it is close to Lorentzian, as for the standard ion line of incoherent scatter (IS). The EISCAT PMWE spectral width is about 5–7 m s−1 at 64–67 km and 7–10 m s−1 at 68–70 km. At the lower altitudes the PMWE spectral widths are close to those for the IS ion line derived from the EISCAT data outside the layers. At the higher altitudes the PMWE spectra are broader by 2–4 m s−1 than those for the ion line. The ESRAD PMWE spectral widths at 67–72 km altitude are 3–5 m s−1, that is, 2–4 m s−1 larger than ion line spectral widths modelled for the ESRAD radar. The PMWE spectral widths for both EISCAT and ESRAD showed no dependence on the echo strength. It was found that all these facts cannot be explained by turbulent origin of the echoes. We suggested that evanescent perturbations in the electron gas generated by the incident infrasound waves may explain the observed PMWE spectral widths. However, a complete theory of radar scatter from this kind of disturbance needs to be developed before a full conclusion can be made.

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The Effect of Forbush Decreases on the Polar-Night HOx Concentration Affecting Stratospheric Ozone

Frontiers in Earth Science ◽

10.3389/feart.2020.618583 ◽

2021 ◽

Vol 8 ◽

Author(s):

Irina Mironova ◽

Arseniy Karagodin-Doyennel ◽

Eugene Rozanov

Keyword(s):

Forbush Decrease ◽

Cosmic Ray ◽

Solar Proton ◽

Polar Night ◽

Forbush Decreases ◽

Ozone Loss ◽

Solar Proton Events ◽

Hydrogen Oxide ◽

The Impact ◽

Ionization Rates

It is well-known that energetic particle precipitations during solar proton events increase ionization rates in the middle atmosphere enhancing the production of hydrogen oxide radicals (HOx) involved in the catalytic ozone destruction cycle. There are many studies where the contribution of energetic particles to the formation of hydrogen oxide radicals and ozone loss has been widely investigated. However, until now, there was no solid evidence that the reduction in galactic cosmic ray fluxes during a magnetic storm, known as Forbush-effect, directly and noticeably affects the polar-night stratospheric chemistry. Here, the impact of the Forbush decrease on the behavior of hydrogen oxide radicals was explored using the chemistry-climate model SOCOLv2. We found that hydrogen oxide radical lost about half of its concentration over the polar boreal night stratosphere owing to a reduction in ionization rates caused by Forbush decreases after solar proton events occurred on 17 and 20 of January 2005. The robust response in ozone was not found. There is not any statistically significant response in (NOx) on Forbush decrease events as well as over summer time in the southern polar region. The results of this study can be used to increase the veracity of ozone loss estimation if stronger Forbush events can have place.

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