scholarly journals Relationship between solar activity and Δ14C peaks in AD 775, AD 994, and 660 BC

Radiocarbon ◽  
2017 ◽  
Vol 59 (4) ◽  
pp. 1147-1156 ◽  
Author(s):  
Junghun Park ◽  
John Southon ◽  
Simon Fahrni ◽  
Pearce Paul Creasman ◽  
Richard Mewaldt
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
Solar Energetic Particle ◽  
Peak Height ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
High Solar Activity ◽  
Published Data ◽  
Enhanced Production ◽  
Mass Ejection

ABSTRACTSince the AD 775 and AD 994 Δ14C peak (henceforth M12) was first measured by Miyake et al. (2012, 2013), several possible production mechanisms for these spike have been suggested, but the work of Mekhaldi et al. (2015) shows that a very soft energy spectrum was involved, implying that a strong solar energetic particle (SEP) event (or series of events) was responsible. Here we present Δ14C values from AD 721–820 Sequoiadendron giganteum annual tree-ring samples from Sequoia National Park in California, USA, together with Δ14C in German oak from 650–670 BC. The AD 721–820 measurements confirm that a sharp Δ14C peak exists at AD 775, with a peak height of approximately 15‰ and show that this spike was preceded by several decades of rapidly decreasing Δ14C. A sharp peak is also present at 660 BC, with a peak height of about 10‰, and published data (Reimer et al. 2013) indicate that it too was preceded by a multi-decadal Δ14C decrease, suggesting that solar activity was very strong just prior to both Δ14C peaks and may be causally related. During periods of strong solar activity there is increased probability for coronal mass ejection (CME) events that can subject the Earth’s atmosphere to high fluencies of solar energetic particles (SEPs). Periods of high solar activity (such as one in October–November 2003) can also often include many large, fast CMEs increasing the probability of geomagnetic storms. In this paper we suggest that the combination of large SEP events and elevated geomagnetic activity can lead to enhanced production of 14C and other cosmogenic isotopes by increasing the area of the atmosphere that is irradiated by high solar energetic particles.

Acceleration of Solar Energetic Particles in CME-Driven Coronal Shocks up to 30 Rs

2021 ◽  
Author(s):  
Kamen Kozarev ◽  
Mohamed Nedal ◽  
Rositsa Miteva ◽  
Pietro Zucca ◽  
Momchil Dechev
Keyword(s):  
Emission Measure ◽  
Realistic Model ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Shock Acceleration ◽  
Quiet Time ◽  
Diffusive Shock Acceleration ◽  
Important Region ◽  
Wave Surfaces ◽  
Mass Ejection

<p>The lower and middle solar corona up to about 30 solar radii is thought to be an important region for early acceleration and transport of solar energetic particles (SEPs) by coronal mass ejection-driven shock waves. There, these waves propagate into a highly variable dynamic medium with steep gradients and rapidly expanding coronal magnetic fields, which modulates the particle acceleration near the shock/wave surfaces, and the way SEPs spread into the heliosphere. We present a study modeling the acceleration of SEPs in over 50 separate global coronal shock events between 1 and 30 solar radii. As part of the SPREAdFAST framework project, we analyzed the interaction of off-limb coronal bright fronts (CBF) observed with the SDO/AIA EUV telescope with realistic model coronal plasma based on results from synoptic magnetohydrodynamic (MHD) and differential emission measure (DEM) models. We used realistic quiet-time proton spectra observed near Earth to form seed suprathermal populations accelerated in our diffusive shock acceleration model (Kozarev & Schwadron, 2016). We summarize our findings and present implications for nowcasting SEP acceleration and heliospheric connectivity.</p>

scholarly journals THE VERY UNUSUAL INTERPLANETARY CORONAL MASS EJECTION OF 2012 JULY 23: A BLAST WAVE MEDIATED BY SOLAR ENERGETIC PARTICLES

2013 ◽  
Vol 770 (1) ◽  
pp. 38 ◽  
Author(s):  
C. T. Russell ◽  
R. A. Mewaldt ◽  
J. G. Luhmann ◽  
G. M. Mason ◽  
T. T. von Rosenvinge ◽  
...  
Keyword(s):  
Coronal Mass Ejection ◽  
Blast Wave ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Interplanetary Coronal Mass Ejection ◽  
Mass Ejection

scholarly journals Accuracy of Global Ionosphere Maps in Relation to Their Time Interval

2021 ◽  
Vol 13 (18) ◽  
pp. 3552
Author(s):  
Beata Milanowska ◽  
Paweł Wielgosz ◽  
Anna Krypiak-Gregorczyk ◽  
Wojciech Jarmołowski
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
High Solar Activity ◽  
Time Interval ◽  
Electron Content ◽  
Dual Frequency ◽  
Total Electron ◽  
Low Latitudes ◽  
Globally Distributed ◽  
Gnss Observations

Global ionosphere maps (GIMs) representing ionospheric total electron content (TEC) are applicable in many scientific and engineering applications. However, the GIMs provided by seven Ionosphere Associated Analysis Centers (IAACs) are generated with different temporal resolutions and using different modeling techniques. In this study, we focused on the influence of map time interval on the empirical accuracy of these ionospheric products. We investigated performance of the high-resolution GIMs during high (2014) and low (2018) solar activity periods as well as under geomagnetic storms (19 February 2014 and 17 March 2015). In each of the analyzed periods, GIMs were also assessed over different geomagnetic latitudes. For the evaluation, we used direct comparison of GIM-derived slant TEC (STEC) with dual-frequency GNSS observations obtained from 18 globally distributed stations. In order to perform a comprehensive study, we also evaluated GIMs with respect to altimetry-derived vertical TEC (VTEC) obtained from the Jason-2 and Jason-3 satellites. The study confirmed the influence of GIMs time interval on the provided TEC accuracy, which was particularly evident during high solar activity, geomagnetic storms, and also at low latitudes. The results show that 120-min interval contributes significantly to the accuracy degradation, whereas 60-min one is sufficient to maintain TEC accuracy.

Solar Energetic Particle Events at the Rise Phase of the 23rd Solar Activity Cycle Registered aboard the Spacecraft “INTERBALL-2”

2000 ◽  
Vol 179 ◽  
pp. 251-254
Author(s):  
Vladislav Timofeev ◽  
Sergey Starodubtsev
Keyword(s):  
Solar Activity ◽  
Solar Flares ◽  
Energetic Particle ◽  
Solar Energetic Particle ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Solar Energetic Particle Events ◽  
Mass Ejection ◽  
Rise Phase ◽  
23Rd Solar Activity Cycle

AbstractThe experiment with 10K-80 aboard the INTER-BALL-2 (which detects protons with energies > 7, 27–41, 41–58, 58–88, 88–180 and 180–300 MeV) registered six events of the solar energetic particle (SEP) increase. These events are during the initial rise phase of the 23rd solar activity cycle. Solar flares with the SEP generation are accompanied by coronal mass ejection (CME). Here we analyze the dynamics of the differential energy spectrum at different phases of the SEP increase.

scholarly journals Propagation of Solar Energetic Particles During Multiple Coronal Mass Ejection Events

Solar Physics ◽  
2016 ◽  
Vol 291 (2) ◽  
pp. 487-511 ◽  
Author(s):  
Silja Pohjolainen ◽  
Firas Al-Hamadani ◽  
Eino Valtonen
Keyword(s):  
Coronal Mass Ejection ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Mass Ejection

scholarly journals Multi-station investigation of spread F over Europe during low to high solar activity

2018 ◽  
Vol 8 ◽  
pp. A27 ◽  
Author(s):  
Krishnendu Sekhar Paul ◽  
Haris Haralambous ◽  
Christina Oikonomou ◽  
Ashik Paul ◽  
Anna Belehaki ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Occurrence Rate ◽  
High Solar Activity ◽  
Solar Cycle Variation ◽  
F Region ◽  
Perkins Instability ◽  
Spread F ◽  
Triggering Mechanisms

Spread F is an ionospheric phenomenon which has been reported and analyzed extensively over equatorial regions on the basis of the Rayleigh-Taylor (R-T) instability. It has also been investigated over midlatitude regions, mostly over the Southern Hemisphere with its generation attributed to the Perkins instability mechanism. Over midlatitudes it has also been correlated with geomagnetic storms through the excitation of travelling ionospheric disturbances (TIDs) and subsequent F region uplifts. The present study deals with the occurrence rate of nighttime spread F events and their diurnal, seasonal and solar cycle variation observed over three stations in the European longitude sector namely Nicosia (geographic Lat: 35.29 °N, Long: 33.38 °E geographic: geomagnetic Lat: 29.38 °N), Athens (geographic Lat: 37.98 °N, Long: 23.73 °E geographic: geomagnetic Lat: 34.61 °N) and Pruhonice (geographic Lat: 50.05 °N, Long: 14.41 °E geographic: geomagnetic Lat: 47.7 °N) during 2009, 2015 and 2016 encompassing periods of low, medium and high solar activity, respectively. The latitudinal and longitudinal variation of spread F occurrence was examined by considering different instability triggering mechanisms and precursors which past literature identified as critical to the generation of spread F events. The main findings of this investigation is an inverse solar cycle and annual temporal dependence of the spread F occurrence rate and a different dominant spread F type between low and high European midlatitudes.

scholarly journals Dusk-to-nighttime enhancement of mid-latitude <i>Nm</i>F2 in local summer: inter-hemispheric asymmetry and solar activity dependence

2015 ◽  
Vol 33 (6) ◽  
pp. 711-718 ◽  
Author(s):  
Y. Chen ◽  
L. Liu ◽  
H. Le ◽  
W. Wan ◽  
H. Zhang
Keyword(s):  
Solar Activity ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Peak Height ◽  
Activity Level ◽  
High Solar Activity ◽  
Activity Levels ◽  
Solar Activity Level ◽  
Latitudinal Dependence ◽  
The Difference

Abstract. In this paper ionosonde observations in the East Asia–Australia sector were collected to investigate dusk-to-nighttime enhancement of mid-latitude summer NmF2 (maximum electron density of the F2 layer) within the framework of NmF2 diurnal variation. NmF2 were normalized to two solar activity levels to investigate the dependence of the dusk-to-nighttime enhancement on solar activity. The dusk-to-nighttime enhancement of NmF2 is more evident at Northern Hemisphere stations than at Southern Hemisphere stations, with a remarkable latitudinal dependence. The dusk-to-nighttime enhancement shows both increasing and declining trends with solar activity increasing, which is somewhat different from previous conclusions. The difference in the dusk-to-nighttime enhancement between Southern Hemisphere and Northern Hemisphere stations is possibly related to the offset of the geomagnetic axis from the geographic axis. hmF2 (peak height of the F2 layer) diurnal variations show that daytime hmF2 begins to increase much earlier at low solar activity level than at high solar activity level at northern Akita and Wakkanai stations where the dusk-to-nighttime enhancement is more prominent at low solar activity level than at high solar activity level. That implies neutral wind phase is possibly also important for nighttime enhancement.

scholarly journals Response of the Antarctic Ionosphere to Some Intense Geomagnetic Storms

2017 ◽  
Vol 11 (1) ◽  
pp. 16-28
Author(s):  
Gustavo A. Mansilla
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
Recovery Phase ◽  
High Solar Activity ◽  
Negative Effects ◽  
Storm Effects ◽  
Positive Effects ◽  
Physical Mechanisms ◽  
Last Stage ◽  
The Antarctic

Background:The effect of geomagnetic storms on the mid-high latitude F2 region is studied.Method:For this purpose, foF2 data from four Antarctic stations were analyzed during three intense magnetic storms occurred in high solar activity (years 2002 and 2003). In general, negative storm effects irrespective of the local time were observed during the first part of the storms (main phase). Negative effects were also observed more often than positive effects during the first part of the recovery phase, which seems to indicate almost no longitudinal dependence in this stage of the storm.Conclusion:The negative effects frequently changed to positive during the last stage of the recovery. Several physical mechanisms were operative during the different stages of the storms.

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