The role of atomic oxygen concentration in the ionization balance of the lower ionosphere during solar proton events

Osepian, A.; Tereschenko, V.; Dalin, Peter; Kirkwood, S.

doi:10.5194/angeo-26-131-2008

Cited by 20 publications

(24 citation statements)

References 40 publications

(55 reference statements)

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“…Computation of ionization rate profiles, and the ionchemistry modelling which is needed to calculate electron density profiles and CNA, requires complex software, with the possibility of coding errors. Therefore, for the present study, results have been carefully compared to the independently coded model described in (Osepian et al, 2008(Osepian et al, , 2009a and Barabash et al (2012) (which uses the same Dregion ionization sources, the same positive-ion model and a more complex negative-ion model with four ions:…”

Section: Ion and No Production Rate Modelmentioning

confidence: 99%

Ionization and NO production in the polar mesosphere during high-speed solar wind streams: model validation and comparison with NO enhancements observed by Odin-SMR

et al. 2015

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Abstract. Precipitation of high-energy electrons (EEP) into the polar middle atmosphere is a potential source of significant production of odd nitrogen, which may play a role in stratospheric ozone destruction and in perturbing large-scale atmospheric circulation patterns. High-speed streams of solar wind (HSS) are a major source of energization and precipitation of electrons from the Earth's radiation belts, but it remains to be determined whether these electrons make a significant contribution to the odd-nitrogen budget in the middle atmosphere when compared to production by solar protons or by lower-energy (auroral) electrons at higher altitudes, with subsequent downward transport. Satellite observations of EEP are available, but their accuracy is not well established. Studies of the ionization of the atmosphere in response to EEP, in terms of cosmic-noise absorption (CNA), have indicated an unexplained seasonal variation in HSS-related effects and have suggested possible order-ofmagnitude underestimates of the EEP fluxes by the satellite observations in some circumstances. Here we use a model of ionization by EEP coupled with an ion chemistry model to show that published average EEP fluxes, during HSS events, from satellite measurements (Meredith et al., 2011), are fully consistent with the published average CNA response (Kavanagh et al., 2012). The seasonal variation of CNA response can be explained by ion chemistry with no need for any seasonal variation in EEP. Average EEP fluxes are used to estimate production rate profiles of nitric oxide between 60 and 100 km heights over Antarctica for a series of unusually well separated HSS events in austral winter 2010. These are compared to observations of changes in nitric oxide during the events, made by the sub-millimetre microwave radiometer on the Odin spacecraft. The observations show strong increases of nitric oxide amounts between 75 and 90 km heights, at all latitudes poleward of 60 • S, about 10 days after the arrival of the HSS. These are of the same order of magnitude but generally larger than would be expected from direct production by HSS-associated EEP, indicating that downward transport likely contributes in addition to direct production.

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Section: Ion and No Production Rate Modelmentioning

confidence: 99%

Ionization and NO production in the polar mesosphere during high-speed solar wind streams: model validation and comparison with NO enhancements observed by Odin-SMR

et al. 2015

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“…The ion-chemical model developed by Smirnova et al (1988) for the lower ionosphere has been used by Osepian et al (2008Osepian et al ( , 2009a to investigate the influence of the atomic oxygen and ozone concentrations on the electron density and the ion composition at different altitudes in the D-region during solar proton events, when there are favorable conditions for accurate measurements of electron density in the whole D-region, including the lower altitudes. The total PGI (Polar Geophysical Institute) model of ionizationrecombination cycle for the D-region takes into account sources of ionization, ion-molecular reactions that form positive cluster ions and complex negative ions from the primary ions, their dependence on temperature and number densities of minor neutral constituents, electron attachment to neutrals, electron photo-detachment of negative ions, photodissociation of negative ions, recombination of positive ions with electrons, reactions of ion-ion recombination.…”

Section: Introductionmentioning

confidence: 99%

Electron density profiles in the quiet lower ionosphere based on the results of modeling and experimental data

et al. 2012

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Abstract. The theoretical PGI (Polar Geophysical Institute) model for the quiet lower ionosphere has been applied for computing the ionization rate and electron density profiles in the summer and winter D-region at solar zenith angles less than 80 • and larger than 99 • under steady state conditions. In order to minimize possible errors in estimation of ionization rates provided by solar electromagnetic radiation and to obtain the most exact values of electron density, each wavelength range of the solar spectrum has been divided into several intervals and the relations between the solar radiation intensity at these wavelengths and the solar activity index F 10.7 have been incorporated into the model. Influence of minor neutral species (NO, H 2 O, O, O 3 ) concentrations on the electron number density at different altitudes of the sunlit quiet D-region has been examined. The results demonstrate that at altitudes above 70 km, the modeled electron density is most sensitive to variations of nitric oxide concentration. Changes of water vapor concentration in the whole altitude range of the mesosphere influence the electron density only in the narrow height interval 73-85 km. The effect of the change of atomic oxygen and ozone concentration is the least significant and takes place only below 70 km.Model responses to changes of the solar zenith angle, solar activity (low-high) and season (summer-winter) have been considered. Modeled electron density profiles have been evaluated by comparison with experimental profiles available from the rocket measurements for the same conditions. It is demonstrated that the theoretical model for the quiet lower ionosphere is quite effective in describing variations in ionization rate, electron number density and effective recombination coefficient as functions of solar zenith angle, solar activity and season. The model may be used for solving inverse tasks, in particular, for estimations of nitric oxide concentration in the mesosphere.

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“…This forms the basis of the theoretical chemical model applied in the present study and is described detail in Osepian et al (2008). Fig.…”

Section: Influence Of the Ozone Concentration On The Ion Composition mentioning

confidence: 99%

“…We use a radiowave frequency of 30 MHz since this is a common standard for riometers and allows easy comparison with other publications. For ν ef (h) we use the expressions deduced by Banks (1966) from the measurements results of electron cross sections for momentum transfer with the neutral particles of the atmosphere (N 2 , O 2 , O,): molecules (from the NRLMSISE-00 model of the neutral atmosphere, described by Picone et al, 2002) and of the atomic oxygen O (for SPE -from Osepian et al, 2008). Under condition of the thermal equilibrium (T e =T ) the expressions (Eq.…”

Section: Ion Composition and Electron Density For Different Concentramentioning

confidence: 99%

“…The influence of the concentration of nitric oxide on the N e height-profile has been considered by Verronen et al (2002). The role of the atomic oxygen concentration in forming the electron density profile during a solar proton event (SPE) has been investigated, in particular, by Osepian et al (2008). Ondraskova et al (2008) have considered the influence of solar illumination on the ion-chemistry and N e profile, comparing modelled responses between polar night and polar day.…”

Section: Introductionmentioning

confidence: 99%

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The influence of ozone concentration on the lower ionosphere – modelling and measurements during the 29–30 October 2003 solar proton event

2009

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Abstract.A numerical model of D-region ion chemistry is used to study the influence of the ozone concentration in the mesosphere on ion-composition and electron density during solar proton events (SPE). We find a strong sensitivity in the lower part of the D-region, where negative ions play a major role in the ionization balance. We have chosen the strong SPE on 29-30 October 2003 when very intense proton fluxes with a hard energetic spectrum were observed. Deep penetration into the atmosphere by the proton fluxes and strong ionisation allows us to use measurements of electron density, made by the EISCAT 224 MHz radar, starting from as low as 55 km. We compare the electron density profiles with model results to determine which ozone concentration profiles are the most appropriate for mesospheric altitudes under SPE conditions. We show that, during daytime, an ozone profile corresponding to depletion by a factor of 2 compared to minimum model concentrations for quiet conditions (Rodrigo et al., 1986), is needed to give model electron density profiles consistent with observations. Simple incorporation of minor neutral constituent profiles (NO, O and O 3 ) appropriate for SPE conditions into ion-chemistry models will allow more accurate modeling of electron and ion densities during such events, without the need to apply a complete chemical model calculating all neutral species.

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The role of atomic oxygen concentration in the ionization balance of the lower ionosphere during solar proton events

Cited by 20 publications

References 40 publications

Ionization and NO production in the polar mesosphere during high-speed solar wind streams: model validation and comparison with NO enhancements observed by Odin-SMR

Ionization and NO production in the polar mesosphere during high-speed solar wind streams: model validation and comparison with NO enhancements observed by Odin-SMR

Electron density profiles in the quiet lower ionosphere based on the results of modeling and experimental data

The influence of ozone concentration on the lower ionosphere – modelling and measurements during the 29–30 October 2003 solar proton event

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