C/NOFS in situ and beacon measurements during the main phase of the first magnetic storms within solar cycle 24

3He-rich solar energetic particle (SEP) events are characterized by a peculiar elemental composition with rare species like 3He or ultra-heavy ions tremendously enhanced over the solar system abundances. We report on 3He rich SEP periods measured by the Suprathermal Ion Telescope (SIT) onboard STEREO-A beginning in 2007 until 2020, covering the whole solar cycle 24. The mass resolution capabilities of SIT do not allow to easily distinguish between 3He and 4He especially in cases of a low 3He to 4He ratio. We therefore developed a semi-automatic detection algorithm to find time periods during which a 3He enhancement can be statistically determined. Using this method we found 112 3He rich periods. These periods were further examined in regards of their 3He/4He and Fe/O ratio.&#160; Previously about ten 3He-rich SEP periods measured by SIT on STEREO-A have been reported. An association with in-situ electron measurements by STEREO-SEPT and STEREO-STE showed that ~60% of the 112 periods are accompanied with electron events. The here presented catalogue of 3He rich periods is intended to serve as a reference for the community.

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Investigation of the possibility of GIC development in Greece during the strongest magnetic storms of solar cycle 24

10.5194/egusphere-egu21-8410 ◽

2021 ◽

Author(s):

Adamantia Zoe Boutsi ◽

Georgios Balasis ◽

Ioannis A. Daglis ◽

Kanaris Tsinganos ◽

Omiros Giannakis

Keyword(s):

Solar Cycle ◽

Magnetic Storms ◽

Geoelectric Field ◽

Storm Events ◽

Power Networks ◽

Geomagnetically Induced Currents ◽

Middle Latitudes ◽

Solar Cycle 24 ◽

Cycle 24 ◽

Index Value

Geomagnetically Induced Currents (GIC) constitute an integral part of the space weather research and a subject of ever-growing attention for countries located in the low and middle latitudes. A series of recent studies highlights the importance of considering GIC risks for the Mediterranean region. Here, we exploit data from the HellENIc GeoMagnetic Array (ENIGMA), which is located in Greece, complemented by magnetic observatories in Italy, to calculate corresponding values of the GIC index, i.e., a proxy of the geoelectric field calculated entirely from geomagnetic field variations. We perform our analysis for the most intense magnetic storms (Dst<-150 nT) of solar cycle 24. Our results show a good correlation between the storm sudden commencement (SSC) and an increase of the GIC index value. These investigations indicate that despite the elevated amplitude of the GIC index the associated risk remains at low level for the power networks in Greece and Italy during the considered storm events.

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Geomagnetic Consequences of Interacting CMEs of June 13-14, 2012

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317010857 ◽

2017 ◽

Vol 13 (S335) ◽

pp. 65-68

Author(s):

Nandita Srivastava ◽

Zavkiddin Mirtoshev ◽

Wageesh Mishra

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Solar Cycle ◽

Geomagnetic Storm ◽

Solar Wind Plasma ◽

Single Step ◽

Solar Cycle 24 ◽

In Situ Observations ◽

Cycle 24

AbstractWe have studied the consequences of interacting coronal mass ejections (CMEs) of June 13-14, 2012 which were directed towards Earth and caused a moderate geomagnetic storm with Dst index ~ −86 nT. We analysed the in-situ observations of the solar wind plasma and magnetic field parameters obtained from the OMNI database for these CMEs. The in-situ observations show that the interacting CMEs arrive at Earth with the strongest (~ 150 nT) Sudden Storm Commencement (SSC) of the solar cycle 24. We compared these interacting CMEs to a similar interaction event which occurred during November 9-10, 2012. This occurred in the same phase of the solar cycle 24 but resulted in an intense geomagnetic storm (Dst ~ −108 nT), as reported by Mishra et al. (2015). Our analysis shows that in the June event, the interaction led to a merged structure at 1 AU while in the case of November 2012 event, the interacted CMEs arrived as two distinct structures at 1 AU. The geomagnetic signatures of the two cases reveal that both resulted in a single step geomagnetic storm.

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Low frequency radio observations of the ‘background’ corona during the declining phase of solar cycle 24

2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) ◽

10.23919/ursiap-rasc.2019.8738381 ◽

2019 ◽

Author(s):

M. Vrunda ◽

R. Ramesh ◽

C. Kathiravan ◽

M. Rajesh

Keyword(s):

Solar Cycle ◽

Low Frequency ◽

Radio Observations ◽

Solar Cycle 24 ◽

Cycle 24

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Regression Analysis of Sunspot Numbers for the Solar Cycle 24 in Comparison to Previous Three Cycles

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v4i2.2030 ◽

2014 ◽

Vol 4 (2) ◽

pp. 477-483

Author(s):

Debojyoti Halder

Keyword(s):

Regression Analysis ◽

Solar Cycle ◽

Sunspot Number ◽

The Sun ◽

Sunspot Numbers ◽

Solar Cycle 24 ◽

Current Cycle ◽

Cycle 24

Sunspots are temporary phenomena on the photosphere of the Sun which appear visibly as dark spots compared to surrounding regions. Sunspot populations usually rise fast but fall more slowly when observed for any particular solar cycle. The sunspot numbers for the current cycle 24 and the previous three cycles have been plotted for duration of first four years for each of them. It appears that the value of peak sunspot number for solar cycle 24 is smaller than the three preceding cycles. When regression analysis is made it exhibits a trend of slow rising phase of the cycle 24 compared to previous three cycles. Our analysis further shows that cycle 24 is approaching to a longer-period but with smaller occurrences of sunspot number.

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