Comment on “Atmospheric ionization by high‐fluence, hard spectrum solar proton events and their probable appearance in the ice core archive” by A. L. Melott et al.

Duderstadt, K.; Dibb, Jack E.; Jackman, Charles H.; Randall, C. E.; Schwadron, N. A.; Solomon, Stanley C.; Spence, H. E.

doi:10.1002/2016jd025220

Cited by 3 publications

(2 citation statements)

References 27 publications

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“…The new spectral fluences will be also useful in various applications of SEP influence on terrestrial effects such as cosmic-ray-induced ionisation (e.g., Jackman et al 2008;Usoskin et al 2011;Duderstadt et al 2016), radiation hazards (e.g., Feynman et al 1993;Jiggens et al 2014;Mishev et al 2015;Raukunen et al 2018), or cosmogenic isotope production (Webber et al 2007;Kovaltsov et al 2014;Mekhaldi et al 2015). The latter is of particular importance for studies of the reference SEP events (Cliver et al 2014;Usoskin et al 2020b), and, accordingly, to a more precise assessment of historical extreme solar particle storms (Miyake et al 2019).…”

Section: Discussionmentioning

confidence: 99%

New reconstruction of event-integrated spectra (spectral fluences) for major solar energetic particle events

Koldobskiy

Raukunen

Vainio

et al. 2021

A&A

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Aims. Fluences of solar energetic particles (SEPs) are not easy to evaluate, especially for high-energy events (i.e. ground-level enhancements, GLEs). Earlier estimates of event-integrated SEP fluences for GLEs were based on partly outdated assumptions and data, and they required revisions. Here, we present the results of a full revision of the spectral fluences for most major SEP events (GLEs) for the period from 1956 to 2017 using updated low-energy flux estimates along with greatly revisited high-energy flux data and applying the newly invented reconstruction method including an improved neutron-monitor yield function. Methods. Low- and high-energy parts of the SEP fluence were estimated using a revised space-borne/ionospheric data and ground-based neutron monitors, respectively. The measured data were fitted by the modified Band function spectral shape. The best-fit parameters and their uncertainties were assessed using a direct Monte Carlo method. Results. A full reconstruction of the event-integrated spectral fluences was performed in the energy range above 30 MeV, parametrised and tabulated for easy use along with estimates of the 68% confidence intervals. Conclusions. This forms a solid basis for more precise studies of the physics of solar eruptive events and the transport of energetic particles in the interplanetary medium, as well as the related applications.

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Section: Discussionmentioning

confidence: 99%

New reconstruction of event-integrated spectra (spectral fluences) for major solar energetic particle events

Koldobskiy

Raukunen

Vainio

et al. 2021

A&A

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“…Instead, calculations of the absolute amount of additional, SPE-produced, inorganic, nitric acid available for prompt deposition are consistent with the observed nitrate increase (Melott et al, 2016). Nevertheless, main conclusion from Duderstadt et al (2016b) is again: ''Existing and previous studies that utilize nitrate peaks in the ice core record to identify individual SPEs are flawed''.…”

Section: Limitations Of Nitrate Methodsmentioning

confidence: 71%

Retrospective analysis of GLEs and estimates of radiation risks

Miroshnichenko

2018

J. Space Weather Space Clim.

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28 February 2017 marked 75 years since the first confident registration of solar cosmic rays (SCRs), i.e., accelerated solar particles with energies from about 106 to ~1010 ÷ 1011 eV. Modern state of the problems related to the studies of Ground Level Enhancements (GLEs) of relativistic SCRs is critically analyzed based on available direct and proxy data. We are also taking into account extremely large fluxes of non-relativistic solar energetic particles (SEPs). Both kinds of SCR events are of great astrophysical and geo-scientific (geophysical) interests. A number of the GLE properties (total statistics, occurrence rate, longitude distribution, ranking of GLEs, a number of specific GLEs – so-called “rogue” SEP events etc.) are discussed in some detail. We note also the problems of GLE identification (definition) by ground-based observations, the difficulties in the studies of weak (“hidden”, or sub-) GLEs etc. One of serious challenges to the problem of radiation hazard in space is a lack of a clear, unambiguous relation between the fluxes (fluences) of relativistic SCR and non-relativistic SEPs. Special attention is paid to the recent debate on the validity, origin and properties of the “ancient” events AD775, AD994, AD1859 (Carrington event) and BC3372. We demonstrate that, in spite of existing uncertainties in proton fluences above 30 MeV, all of them are fitted well by a unique distribution function, at least, with the present level of solar activity. Extremely large SEP events are shown to obey a probabilistic distribution on their fluences with a sharp break in the range of large fluences (or low probabilities). The studies of this kind may be extended for periods with different levels of solar activity in the past and/or in the future. Dose rates at aircraft altitudes are also demonstrated during some GLEs. Several examples of using the SCR data and GLE properties in radiation prediction schemes are considered.

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An Evaluation of Antarctic Ice Core Nitrate Records as a Proxy for Solar Activity

Laluraj,

Waliur,

Meloth

2024

Earth and Space Science

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Nitrate (NO3−) deposition in polar ice sheets archives valuable information on past solar activity. However, interpretation of Antarctic ice core NO3− records as a proxy for past solar activity remains challenging due to multiple sources and processes controlling NO3− variability in ice core records. Here, we present a new high‐resolution ice core NO3− record (1905–2005 CE) from coastal Dronning Maud Land, East Antarctica, to investigate the solar signal and other forcing factors/processes in controlling ice core NO3− variability. Our record exhibits significant periodicity in the range of 8–12 years frequency band during 1940–2005 CE, apparently identified as the signal of ∼11 year sunspot cycle; however, such signal was not detected in the previous interval during 1905–1940 CE. To address the discontinuous and/or obscured signals in the present ice core record and inconsistency among various Antarctica ice core records, we extended our investigations to 10 ice core NO3− records from various regions of Antarctica. Analysis of seven records for the common interval from 1738 to 1990 CE reveals dominant periodicities of 8–12 years, indicating solar forcing as a primary driver, followed by precipitation modulated by El Niño‐Southern Oscillation and Pacific Decadal Oscillation. Further, our investigation reveals that the solar signal extracted from multiple records becomes undetectable when mean annual hemispheric sunspot numbers larger than 140, suggesting this is a threshold limit for detecting the solar signal. These findings will improve our present understanding of ice core NO3− records as a proxy for past solar activity.

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Comment on “Atmospheric ionization by high‐fluence, hard spectrum solar proton events and their probable appearance in the ice core archive” by A. L. Melott et al.

Abstract: Key Points It is necessary to include preexisting stratospheric HNO3 in an analysis of nitrate deposition from SPEs SPE‐produced nitrate is negligible compared to the stratospheric background

Cited by 3 publications

References 27 publications

New reconstruction of event-integrated spectra (spectral fluences) for major solar energetic particle events

New reconstruction of event-integrated spectra (spectral fluences) for major solar energetic particle events

Retrospective analysis of GLEs and estimates of radiation risks

An Evaluation of Antarctic Ice Core Nitrate Records as a Proxy for Solar Activity

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