scholarly journals Periods of High Intensity Solar Proton Flux

2012 ◽  
Vol 59 (4) ◽  
pp. 1054-1059 ◽  
Author(s):  
Michael A. Xapsos ◽  
Craig A. Stauffer ◽  
Thomas M. Jordan ◽  
James H. Adams ◽  
William F. Dietrich
Keyword(s):  
High Intensity ◽  
Solar Proton ◽  
Proton Flux

scholarly journals Polar cap absorption events of November 2001 at Terra Nova Bay, Antarctica

2004 ◽  
Vol 22 (5) ◽  
pp. 1633-1648 ◽  
Author(s):  
L. Perrone ◽  
L. Alfonsi ◽  
V. Romano ◽  
G. de Franceschi
Keyword(s):  
Solar Physics ◽  
Threshold Energy ◽  
Solar Proton ◽  
Proton Flux ◽  
Polar Cap ◽  
Geomagnetic Disturbances ◽  
Terra Nova Bay ◽  
Cross Correlation Analysis ◽  
Terra Nova ◽  
The Impact

Abstract. Polar cap absorption (PCA) events recorded during November 2001 are investigated by observations of ionospheric absorption of a 30MHz riometer installed at Terra Nova Bay (Antarctica), and of solar proton flux, monitored by the NOAA-GOES8 satellite in geo-synchronous orbit. During this period three solar proton events (SPE) on 4, 19 and 23 November occurred. Two of these are among the dozen most intense events since 1954 and during the current solar cycle (23rd), the event of 4 November shows the greatest proton flux at energies >10MeV. Many factors contribute to the peak intensity of the two SPE biggest events, one is the Coronal Mass Ejection (CME) speed, other factors are the ambient population of SPE and the shock front due to the CME. During these events absorption peaks of several dB (~20dB) are observed at Terra Nova Bay, tens of minutes after the impact of fast halo CMEs on the geomagnetic field. Results of a cross-correlation analysis show that the first hour of absorption is mainly produced by 84–500MeV protons in the case of the 4 November event and by 15–44MeV protons for the event of 23 November, whereas in the entire event the contribution to the absorption is due chiefly to 4.2–82MeV (4 November) and by 4.2–14.5MeV (23 November). Good agreement is generally obtained between observed and calculated absorption by the empirical flux-absorption relationship for threshold energy E0=10MeV. From the residuals one can argue that other factors (e.g. X-ray increases and geomagnetic disturbances) can contribute to the ionospheric absorption.Key words. Ionosphere (Polar Ionosphere, Particle precipitation) – Solar physics (Flares and mass ejections)

scholarly journals The Neutron Flux Variation in the Earth’s Atmosphere Depending on the Solar Proton Flux

2013 ◽  
Vol 03 (04) ◽  
pp. 481-485
Author(s):  
Marina Poje ◽  
Branko Vuković ◽  
Maja Varga Pajtler ◽  
Vanja Radolić ◽  
Igor Miklavčić ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Solar Proton ◽  
Proton Flux ◽  
Flux Variation ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere

scholarly journals On solar protons and polar cap absorption: constraints on an empirical relationship

2004 ◽  
Vol 22 (4) ◽  
pp. 1133-1147 ◽  
Author(s):  
A. J. Kavanagh ◽  
S. R. Marple ◽  
F. Honary ◽  
I. W. McCrea ◽  
A. Senior
Keyword(s):  
Empirical Relationship ◽  
Cosmic Ray ◽  
Solar Proton ◽  
Proton Flux ◽  
High Solar Activity ◽  
Square Root ◽  
Polar Cap ◽  
Integral Flux ◽  
Solar Proton Events ◽  
The Relationship

Abstract. A large database of Solar Proton Events (SPE) from the period 1995 to 2001 is used to investigate the relationship between proton flux at geostationary orbit and Cosmic Noise Absorption (CNA) in the auroral zone. The effect of solar illumination on this relationship is studied in a statistical manner by deriving correlation coefficients of integral flux and absorption as a function of solar zenith angle limit, thus both an upper limit on the angle and the best correlated integral flux of protons are determined (energies in excess of 10MeV). By considering the correlation of various energy ranges (from the GOES 8 differential proton flux channels) with CNA the range of proton energies for which the relationship between flux and absorption is best defined is established (15 to 44MeV), thus confirming previous predictions about which proton energy ranges are most effective in giving rise to absorption during Polar Cap Absorption (PCA) events. An empirical relationship between the square root of the integral proton flux and the absorption, measured by the imaging riometer at Kilpisjärvi (IRIS), is determined and departures from linearity and possible causes are examined. Variations in spectral "hardness" and in collision frequency are demonstrated not to be significant causes of the observed departures from a linear relationship. Geomagnetic activity may be a significant factor in changing the relationship between the absorption and the square root of the integral proton flux, although it is concluded that the cause is likely to be more complex than a straightforward dependence on Kp. It is suggested that the most significant factor might be a bias in the absorption estimates imposed by the presence of Solar Radio Emission (SRE), which is not routinely measured at the operating frequency of IRIS, making its precise effect difficult to quantify. SRE is known to be most prevalent under conditions of high solar activity, such as those that might give rise to solar proton events. Key words. Ionosphere (particle precipitation; solar radiation and cosmic ray effects; polar ionosphere)

scholarly journals Forecast of solar proton flux profiles for well‐connected events

2014 ◽  
Vol 119 (12) ◽  
pp. 9383-9394 ◽  
Author(s):  
Eun‐Young Ji ◽  
Yong‐Jae Moon ◽  
Jinhye Park
Keyword(s):  
Solar Proton ◽  
Proton Flux

scholarly journals Schumann resonance parameters at Kuju station during solar flares

2018 ◽  
Vol 62 ◽  
pp. 01012
Author(s):  
Akihiro Ikeda ◽  
Teiji Uozumi ◽  
Akimasa Yoshikawa ◽  
Akiko Fujimoto ◽  
Shuji Abe
Keyword(s):  
Solar Activity ◽  
Solar Flares ◽  
Solar Proton ◽  
Proton Flux ◽  
Schumann Resonance ◽  
Low Latitude ◽  
X Ray ◽  
High Latitude Region ◽  
D Region ◽  
Latitude Region

We examined the Schumann resonance (SR) at low-latitude station KUJ by comparing with solar X-ray flux and solar proton flux at a geostationary orbit. For intense solar activity in October-November 2003, the reaction of the SR frequency to X-ray enhancement and SPEs was different. The SR frequency in H component increased at the time of the Xray enhancement. The response of SR seems to be caused by the increase of the electron density in the ionospheric D region which ionized by the enhanced solar X-ray flux. In the case of the SPEs, the SR frequency in D component decreased with enhancement of solar proton flux. We suggest that the SPEs caused the decrease of altitude on the ionopheric D region at high-latitude region, and the SR frequency decreased.

scholarly journals Time exceedances for high intensity solar proton fluxes

2011 ◽  
Author(s):  
Michael A. Xapsos ◽  
Craig A. Stauffer ◽  
Thomas M. Jordan ◽  
James H. Adams ◽  
William F. Dietrich
Keyword(s):  
High Intensity ◽  
Solar Proton ◽  
Proton Fluxes

Solar proton flux enhancements at auroral latitudes

1974 ◽  
Vol 79 (7) ◽  
pp. 1099-1103 ◽  
Author(s):  
I. B. McDiarmid ◽  
J. R. Burrows ◽  
Margaret D. Wilson
Keyword(s):  
Solar Proton ◽  
Proton Flux

scholarly journals sensitivity of middle atmospheric ozone to solar proton events: comparison between climate model and satellites

2021 ◽  
Author(s):  
Kenneth Nilsen ◽  
Antti Kero ◽  
Pekka Verronen ◽  
Monika Szelag ◽  
Niilo Kalakoski ◽  
...  
Keyword(s):  
Satellite Data ◽  
Climate Model ◽  
Solar Proton ◽  
Proton Flux ◽  
Data Sets ◽  
Atmospheric Ozone ◽  
Ion Chemistry ◽  
Solar Proton Events ◽  
Good Agreement

<p>Energetic particle precipitation (EPP) impact on the middle atmospheric ozone chemistry plays potentially an important role in the connection between space weather and Earth's climate system. A variant of the Whole Atmosphere Community Climate Model (WACCM-D) implements a detailed set of ionospheric D-region chemistry instead of a simple parameterization used in the earlier WACCM versions, allowing to capture the impact of EPP in more detail, thus improving the model for long-term climate studies. Here, we verify experimentally the ion chemistry of the WACCM-D by analysing the middle atmospheric ozone response to the EPP forcing during well-known solar proton events<span> </span>(SPEs). We use a multi-satellite approach to derive the middle atmospheric sensitivity for the SPE forcing as a statistical relation between the solar proton flux and the consequent ozone change. An identical sensitivity analysis is carried out for the WACCM-D model results, enabling one-to-one comparison with the results derived from the satellite observations. Our results show a good agreement in the sensitivity between satellites and the WACCM-D for nighttime conditions. For daytime conditions, we find a good agreement for the satellite data sets that include the largest SPEs (max proton flux >10^<span>4 </span> pfu). However, for those satellite data-sets with only minor and moderate SPEs, WACCM-D tends to underestimate the sensitivity in daytime conditions. In summary, the comparisons WACCM-D ion chemistry, combined with the transportation, demonstrates a realistic representation of the SPE sensitivity of ozone, and thus provides a conservative platform for long-term EPP impact studies.</p>

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