scholarly journals The Highest Geomagnetic Storms of the Solar Cycle Observed at Ground Level

2018 ◽  
Author(s):  
Carlos E. Navia ◽  
Marcel N. de Oliveira ◽  
Carlos R. A. Augusto
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Ground Level

scholarly journals What can the annual 10Be solar activity reconstructions tell us about historic space weather?

2018 ◽  
Vol 8 ◽  
pp. A23 ◽  
Author(s):  
Luke Barnard ◽  
Ken G. McCracken ◽  
Mat J. Owens ◽  
Mike Lockwood
Keyword(s):  
Solar Cycle ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Solar Energetic Particle ◽  
Ground Level ◽  
Magnetic Activity ◽  
Cycle Phase ◽  
Large Space ◽  
Weather Events ◽  
Solar Magnetic Activity

Context: Cosmogenic isotopes provide useful estimates of past solar magnetic activity, constraining past space climate with reasonable uncertainty. Much less is known about past space weather conditions. Recent advances in the analysis of 10Be by McCracken & Beer (2015, Sol Phys 290: 305–3069) (MB15) suggest that annually resolved 10Be can be significantly affected by solar energetic particle (SEP) fluxes. This poses a problem, and presents an opportunity, as the accurate quantification of past solar magnetic activity requires the SEP effects to be determined and isolated, whilst doing so might provide a valuable record of past SEP fluxes. Aims: We compare the MB15 reconstruction of the heliospheric magnetic field (HMF), with two independent estimates of the HMF derived from sunspot records and geomagnetic variability. We aim to quantify the differences between the HMF reconstructions, and speculate on the origin of these differences. We test whether the differences between the reconstructions appear to depend on known significant space weather events. Methods: We analyse the distributions of the differences between the HMF reconstructions. We consider how the differences vary as a function of solar cycle phase, and, using a Kolmogorov-Smirnov test, we compare the distributions under the two conditions of whether or not large space weather events were known to have occurred. Results: We find that the MB15 reconstructions are generally marginally smaller in magnitude than the sunspot and geomagnetic HMF reconstructions. This bias varies as a function of solar cycle phase, and is largest in the declining phase of the solar cycle. We find that MB15's excision of the years with very large ground level enhancement (GLE) improves the agreement of the 10Be HMF estimate with the sunspot and geomagnetic reconstructions. We find no statistical evidence that GLEs, in general, affect the MB15 reconstruction, but this analysis is limited by having too few samples. We do find evidence that the MB15 reconstructions appear statistically different in years with great geomagnetic storms.

scholarly journals The 2015 Summer Solstice Storm: One of the Major Geomagnetic Storms of Solar Cycle 24 Observed at Ground Level

Solar Physics ◽  
2018 ◽  
Vol 293 (5) ◽  
Author(s):  
C. R. A. Augusto ◽  
C. E. Navia ◽  
M. N. de Oliveira ◽  
A. A. Nepomuceno ◽  
J. P. Raulin ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Ground Level ◽  
Summer Solstice ◽  
Solar Cycle 24 ◽  
Cycle 24

scholarly journals Carrington Longitudinal and Solar Cycle Distribution of the Super Active Regions From 1976 to 2018

2021 ◽  
Author(s):  
MIng-Xian Zhao ◽  
Guiming Le ◽  
Yonghua Liu ◽  
Tian Mao
Keyword(s):  
Solar Cycle ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Active Regions ◽  
Ground Level ◽  
Weather Events ◽  
Flare Index ◽  
Statistical Results ◽  
Extreme Space Weather Events

Abstract We studied the Carrington longitudinal and solar cycle distribution of the super active regions (SARs) from 1976to 2018. There were 51 SARs during this period. We divided the SARs into SARs1 and SARs2. SARs1 refers tothe SARs that produced extreme space weather events including ≥X5.0 flares, ground level events (GLEs) andsuper geomagnetic storms (SGSs: Dst≤ −250 nT), while SARs2 did not produce extreme space weather events.The total number of SARs1 and SARs2 are 32 and 19, respectively. The statistical results show that 34.4%, 65.6%and 78.1% of the SARs1 appeared in the ascending phase, descending phase and in the period from two yearsbefore to the three years after the solar maximum, respectively, while 52.6%, 47.4% and 100% of the SARs2appeared in the ascending phase, descending phase and in the period from two years before to the three years aftersolar maximum, respectively. The Carrington longitude distribution of the SARs1 shows that SARs1 in thelongitudinal scope of [0,150°] produced ≥X5.0 flares and GLEs, while only the SARs1 in the longitude range of[150°,360°] not only produced ≥X5.0 flares and GLEs, but also produced SGSs. The total number of SARsduring a SC has a good correlation with the SC size. However, the largest flare index of a SAR within a SC has apoor correlation with the SC size, implying that the number of SARs in a weak SC will be small. However, aweak SC may have a SAR that can produce very strong solar flare activities.

Characteristics of source location and solar cycle distribution of the strong solar proton events (≥ 1000 pfu) from 1976 to 2018

2021 ◽  
Author(s):  
Gui-Ming Le ◽  
Ming-Xian Zhao ◽  
Qi Li ◽  
Gui-Ang Liu ◽  
Tian Mao ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Ground Level ◽  
Solar Proton ◽  
Western Hemisphere ◽  
Poor Correlation ◽  
The Sun ◽  
The Earth ◽  
Solar Proton Events ◽  
Northern And Southern Hemispheres

Abstract We studied the source locations and solar cycle distribution of strong solar proton events (≥ 1000 pfu) measured at the Earth from 1976 to 2018. There were 43 strong solar proton events (SPEs) during this period. 27.9 per cent of the strong SPEs were ground level enhancement (GLE) events. We detect more strong SPEs coming from the western hemisphere. The strong SPEs were distributed in the region of [E90-W90], extreme SPEs (≥10000 pfu) appeared within the longitudinal area from E30 to W75, while the SPEs with peak fluxes ≥ 20000 pfu concentrated in the range from E30 to W30 and were always accompanied by super geomagnetic storms (Dst ≤−250 nT). The northern and southern hemispheres of the Sun have 23 and 20 strong SPEs, respectively. The ranges S0–S19 and N0–N19 have 13 and 11 strong SPEs, respectively. S20–S45 and N20–N45 have 7 and 12 strong SPEs, respectively, indicating that the N-S asymmetry of strong SPEs mainly occurred in the areas with a latitude greater than 20○ of the two hemispheres of the Sun. The statistical results showed that 48.8 per cent, 51.2 per cent, and 76.7 per cent of the strong SPEs appeared during the rising phase, declining phase, and in the period from two years before to the three years after the solar maximum, respectively. The number of strong SPEs during a solar cycle has a poor correlation with the solar cycle size.

scholarly journals Climatology of Ionospheric Amplitude Scintillation on GNSS Signals at South American Sector During Solar Cycle 24

2021 ◽  
Author(s):  
Eduardo Perez Macho ◽  
Emilia Correia ◽  
Luca Spogli ◽  
Marcio Tadeu de Assis Honorato Muella
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Satellite System ◽  
Scintillation Index ◽  
Ionospheric Scintillation ◽  
South American ◽  
Amplitude Scintillation ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
The Impact

Abstract Scintillations are caused by ionospheric irregularities and can affect the propagation of trans-ionospheric radio signals. One way to understand and predict the impact of such irregularities on Global Navigation Satellite System (GNSS) signals is through the climatological behavior of the ionospheric scintillation indexes during the different phases of a solar cycle. In this work, we investigate the amplitude scintillation index S4 during the full solar cycle 24 at South American (SA) sector, that is featured by the Ionospheric Anomaly (EIA) and by the South Atlantic Magnetic Anomaly (SAMA). We also investigate the daily variation of S4 and two case studies during geomagnetic storms. The results show a significant intensification of amplitude scintillations at northern and southern crest of EIA, especially during the southern hemisphere’s spring/summer seasons, with a higher increase during solar maximum, and after sunset. And particularly at the SAMA region, where the intensity of magnetic field lines is lower, the S4 fluctuations are much higher.

The First Ground-Level Enhancement of Solar Cycle 24 on 17 May 2012 and Its Real-Time Detection

Solar Physics ◽  
2013 ◽  
Vol 289 (1) ◽  
pp. 423-436 ◽  
Author(s):  
A. Papaioannou ◽  
G. Souvatzoglou ◽  
P. Paschalis ◽  
M. Gerontidou ◽  
H. Mavromichalaki
Keyword(s):  
Solar Cycle ◽  
Real Time ◽  
Ground Level ◽  
Ground Level Enhancement ◽  
Solar Cycle 24 ◽  
Real Time Detection ◽  
Cycle 24

Small Size Ground Level Enhancements During Solar Cycle 24

Solar Physics ◽  
2020 ◽  
Vol 295 (7) ◽  
Author(s):  
Leonty I. Miroshnichenko ◽  
Chuan Li ◽  
Victor G. Yanke
Keyword(s):  
Solar Cycle ◽  
Ground Level ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Ground Level Enhancements

scholarly journals Statistics of the largest geomagnetic storms per solar cycle (1844-1993)

1997 ◽  
Vol 15 (6) ◽  
pp. 719-728 ◽  
Author(s):  
D. M. Willis ◽  
P. R. Stevens ◽  
S. R. Crothers
Keyword(s):  
Statistical Analysis ◽  
Solar Cycle ◽  
Geomagnetic Storm ◽  
Extreme Values ◽  
Geomagnetic Storms ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Relative Dispersion ◽  
Solar Cycles ◽  
Aa Index

Abstract. A previous application of extreme-value statistics to the first, second and third largest geomagnetic storms per solar cycle for nine solar cycles is extended to fourteen solar cycles (1844–1993). The intensity of a geomagnetic storm is measured by the magnitude of the daily aa index, rather than the half-daily aa index used previously. Values of the conventional aa index (1868–1993), supplemented by the Helsinki Ak index (1844–1880), provide an almost continuous, and largely homogeneous, daily measure of geomagnetic activity over an interval of 150 years. As in the earlier investigation, analytic expressions giving the probabilities of the three greatest storms (extreme values) per solar cycle, as continuous functions of storm magnitude (aa), are obtained by least-squares fitting of the observations to the appropriate theoretical extreme-value probability functions. These expressions are used to obtain the statistical characteristics of the extreme values; namely, the mode, median, mean, standard deviation and relative dispersion. Since the Ak index may not provide an entirely homogeneous extension of the aa index, the statistical analysis is performed separately for twelve solar cycles (1868–1993), as well as nine solar cycles (1868–1967). The results are utilized to determine the expected ranges of the extreme values as a function of the number of solar cycles. For fourteen solar cycles, the expected ranges of the daily aa index for the first, second and third largest geomagnetic storms per solar cycle decrease monotonically in magnitude, contrary to the situation for the half-daily aa index over nine solar cycles. The observed range of the first extreme daily aa index for fourteen solar cycles is 159–352 nT and for twelve solar cycles is 215–352 nT. In a group of 100 solar cycles the expected ranges are expanded to 137–539 and 177–511 nT, which represent increases of 108% and 144% in the respective ranges. Thus there is at least a 99% probability that the daily aa index will satisfy the condition aa < 550 for the largest geomagnetic storm in the next 100 solar cycles. The statistical analysis is used to infer that remarkable conjugate auroral observations on the night of 16 September 1770, which were recorded during the first voyage of Captain Cook to Australia, occurred during an intense geomagnetic storm.

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