Modelling the effects of the October 1989 solar proton event on mesospheric odd nitrogen using a detailed ion and neutral chemistry model

Verronen, Pekka T.; Turunen, Esa; Ulich, Thomas; Kyrölä, E.

doi:10.5194/angeo-20-1967-2002

Cited by 55 publications

(62 citation statements)

References 41 publications

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“…The changing HANE-injected differential flux at L=1.57 during the operation of an assumed ground based RBR-system, in the same format as Fig. 4. time-scales, and altitudes of these changes are rather similar to the NO x /HO x enhancements and O 3 depletions calculated by the SIC model for large solar proton events (Verronen et al, 2002(Verronen et al, , 2005, confirmed by experimental observations using the GOMOS satellite-bourn instrument Verronen et al, 2005) and subionospheric VLF propagation measurements . Thus while RBR-forced precipitation should be expected to be a rare occurrence, even if it was used to mitigate the effects of intense natural injections while providing a defence against possible HANE-injections, the effects are no more significant than large solar proton events.…”

Section: Modelling Resultssupporting

confidence: 59%

“…Our study made use of SIC version 6.6.0. The model has recently been discussed by Verronen et al (2005), building on original work by Turunen et al (1996) and Verronen et al (2002). A detailed overview of the model was given in Verronen et al (2005), but we summarize in a similar way here to provide background for this study.…”

Section: Sodankylä Ion Chemistry Modelmentioning

confidence: 99%

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The atmospheric implications of radiation belt remediation

Rodger

Clilverd

Ulich³

et al. 2006

Ann. Geophys.

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Abstract. High altitude nuclear explosions (HANEs) and geomagnetic storms can produce large scale injections of relativistic particles into the inner radiation belts. It is recognised that these large increases in >1 MeV trapped electron fluxes can shorten the operational lifetime of low Earth orbiting satellites, threatening a large, valuable population. Therefore, studies are being undertaken to bring about practical human control of the radiation belts, termed "Radiation Belt Remediation" (RBR). Here we consider the upper atmospheric consequences of an RBR system operating over either 1 or 10 days. The RBR-forced neutral chemistry changes, leading to NO x enhancements and O x depletions, are significant during the timescale of the precipitation but are generally not long-lasting. The magnitudes, time-scales, and altitudes of these changes are no more significant than those observed during large solar proton events. In contrast, RBR-operation will lead to unusually intense HF blackouts for about the first half of the operation time, producing large scale disruptions to radio communication and navigation systems. While the neutral atmosphere changes are not particularly important, HF disruptions could be an important area for policy makers to consider, particularly for the remediation of natural injections.

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Section: Modelling Resultssupporting

confidence: 59%

Section: Sodankylä Ion Chemistry Modelmentioning

confidence: 99%

The atmospheric implications of radiation belt remediation

Rodger

Clilverd

Ulich³

et al. 2006

Ann. Geophys.

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“…This study makes use of SIC version 6.9.0. The model has recently been discussed by Verronen et al [2005], building on the original work by Turunen et al [1996] and Verronen et al [2002]. A detailed overview of the model was given by Verronen et al [2005].…”

Section: Nighttime Riometer Absorption Using the Sodankylä Ion And Nementioning

confidence: 99%

Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy

et al. 2007

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[1] In the polar atmosphere, significant chemical and ionization changes occur during solar proton events (SPEs). The access of solar protons to this region is limited by the dynamically changing geomagnetic field. In this study, we have used riometer absorption observations to investigate the accuracy of a model to predict K p -dependent geomagnetic rigidity cutoffs, and hence the changing proton fluxes. The imaging riometer at Halley, Antarctica is ideally situated for such a study, as the rigidity cutoff sweeps back and forth across the instrument's field of view, providing a severe test of the rigidity cutoff model. Using observations from this riometer during five solar proton events, we have confirmed the basic accuracy of this rigidity model. However, we find that the model can be improved by setting a lower K p limit (i.e., K p = 5 instead of 6) at which the rigidity modeling saturates. We also find that, for L > 4.5, the apparent L-shell of the beam moves equatorward. In addition, the Sodankylä Ion and Neutral Chemistry (SIC) model is used to determine an empirical relationship between integral proton precipitation fluxes and nighttime ionosphere riometer absorption, in order to allow consideration of wintertime SPEs. We find that during the nighttime, the proton flux energy threshold is lowered to include protons with energies of >5 MeV in comparison with >10 MeV for the daytime empirical relationships. In addition, we provide an indication of the southern and northern geographic regions inside which SPEs play a role in modifying the neutral chemistry of the stratosphere and mesosphere.Citation: Clilverd, M. A., C. J. Rodger, T. Moffat-Griffin, and P. T. Verronen (2007), Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy,

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“…Initial descriptions of the model are provided by Turunen et al [1996], with neutral species modifications described by Verronen et al [2002]. Solar flux is calculated with the SOLAR2000 model (version 2.23) [Tobiska et al, 2000].…”

Section: Sodankylä Ion Chemistry (Sic) Modelmentioning

confidence: 99%

“…The Sodankylä ion chemistry model (SIC) [see Verronen et al, 2002] models the major chemical reactions and interactions known to occur in the lower ionosphere. It has been used to calculate the effects of a series of SPEs that took place in October/November 2003.…”

Section: Introductionmentioning

confidence: 99%

Modeling polar ionospheric effects during the October–November 2003 solar proton events

et al. 2006

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[1] At Ny Å lesund, Svalbard (78°54 0 N, 11°53 0 E, L $ 18), a narrowband VLF receiver was used to monitor the behavior of the amplitude of several high-power transmitters located in the Northern Hemisphere under the influence of the solar proton events (SPE) of October/November 2003. We have used Sodankylä ion chemistry (SIC) atmospheric model profiles calculated at the midpoint location of the propagation paths in the northern wintertime polar region to investigate the radio propagation properties of several highlatitude paths. Different paths showed different responses to the proton precipitation, but propagation modeling was broadly able to account for most of the positive and negative responses observed. Using the SIC-based electron density profiles, we have been able to develop models of ionospheric effective height (h 0 ) and sharpness (b) in order to describe the D region behavior as a function of proton flux, extending previous work which reported b and h 0 values as functions of the X-ray flux from solar flares. As a result of these models, our understanding of VLF propagation influenced by SPEs is such that VLF observations might be used to predict changes in the ionospheric D region electron density profiles during other particle precipitation events.

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Modelling the effects of the October 1989 solar proton event on mesospheric odd nitrogen using a detailed ion and neutral chemistry model

Cited by 55 publications

References 41 publications

The atmospheric implications of radiation belt remediation

The atmospheric implications of radiation belt remediation

Improved dynamic geomagnetic rigidity cutoff modeling: Testing predictive accuracy

Modeling polar ionospheric effects during the October–November 2003 solar proton events

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