Ulysses solar wind plasma observations during the declining phase of solar cycle 22

Solar Cycle Variation of Cosmic ray Intensity along with Interplanetary and Solar Wind Plasma ParametersGalactic cosmic rays are modulated at their propagation in the heliosphere by the effect of the large-scale structure of the interplanetary medium. A comparison of the variations in the cosmic ray intensity data obtained by neutron monitoring stations with those in geomagnetic disturbance, solar wind velocity (V), interplanetary magnetic field (B), and their product (V' B) near the Earth for the period 1964-2004 has been presented so as to establish a possible correlation between them. We used the hourly averaged cosmic ray counts observed with the neutron monitor in Moscow. It is noteworthy that a significant negative correlation has been observed between the interplanetary magnetic field, product (V' B) and cosmic ray intensity during the solar cycles 21 and 22. The solar wind velocity has a good positive correlation with cosmic ray intensity during solar cycle 21, whereas it shows a weak correlation during cycles 20, 22 and 23. The interplanetary magnetic field shows a weak negative correlation with cosmic rays for solar cycle 20, and a good anti-correlation for solar cycles 21-23 with the cosmic ray intensity, which, in turn, shows a good positive correlation with disturbance time index (Dst) during solar cycles 21 and 22, and a weak correlation for cycles 20 and 23.

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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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Solar Rotational Oscillation and Its Subharmonics in Solar Wind Plasma Field, Geomagnetic, and Cosmic Ray Intensity Indicator in the Solar Cycle 24/25 Minimum

Earth and Space Science ◽

10.1029/2019ea001068 ◽

2020 ◽

Vol 7 (4) ◽

Author(s):

Y. P. Singh

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Cosmic Ray ◽

Solar Wind Plasma ◽

Cosmic Ray Intensity ◽

Rotational Oscillation ◽

Solar Cycle 24 ◽

Cycle 24

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On the Variation of Intermittency of Fast and Slow Solar Wind With Radial Distance, Heliospheric Latitude, and Solar Cycle

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2020.617113 ◽

2021 ◽

Vol 7 ◽

Cited By ~ 1

Author(s):

Anna Wawrzaszek ◽

Marius Echim

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Current Knowledge ◽

Radial Distance ◽

Multifractal Spectrum ◽

Solar Wind Plasma ◽

Distribution Functions ◽

Slow Solar Wind ◽

Cycle Phase ◽

Magnetic Fluctuations

Intermittency, an important property of astrophysical plasma turbulence, is studied extensively during last decades from in-situ measurements of the solar wind plasma and magnetic field in the ecliptic plane and at higher latitudes, and heliocentric distances between 0.3 and 5 Astronomical Units. In this paper, we review the main findings on intermittency derived from investigation of solar wind turbulence for the inertial range of scales. It turns out that our current knowledge on the evolution of intermittency in the heliosphere is based on two missions, Helios two and Ulysses. We discuss the importance of data selection methodologies and applications for heliospheric spacecraft, the different data analysis techniques (the anomalous scaling of the structure function, the non-Gaussianity of the probability distribution functions, the local intermittency measure estimated from a wavelet representation and the multifractal spectrum). Studies show that Alvénic solar wind is less intermittent but reveals increase with the radial distance. Moreover, intermittency is stronger for the magnetic than for velocity fluctuations and is considered to be responsible for the increase with the radial distance of the anisotropy of magnetic fluctuations. The intermittency of fast solar wind at solar minimum decreases with latitude. Finally, the level of intermittency in the solar wind depends on solar cycle phase, reflecting the changes of the state of solar wind and suggesting that the deeper study of origin of fast and slow wind can further improve our understanding of the intermittency.

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On the periodic variations of geomagnetic activity indices Ap and ap

Annales Geophysicae ◽

10.1007/s00585-998-0510-2 ◽

1998 ◽

Vol 16 (5) ◽

pp. 510-517 ◽

Cited By ~ 15

Author(s):

H. Schreiber

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Geomagnetic Activity ◽

Sunspot Cycle ◽

Solar Wind Plasma ◽

Sector Structure ◽

Interplanetary Physics ◽

Before And After ◽

Activity Indices ◽

The Imf

Abstract. Yearly averages of geomagnetic activity indices Ap for the years 1967–1984 are compared to the respective averages of ν2·Bs, where v is the solar wind velocity and Bs is the southward interplanetary magnetic field (IMF) component. The correlation of both quantities is known to be rather good. Comparing the averages of Ap with ν2 and Bs separately we find that, during the declining phase of the solar cycle, ν2 and during the ascending phase Bs have more influence on Ap. According to this observation (using Fourier spectral analysis) the semiannual and 27 days, Ap variations for the years 1932–1993 were analysed separately for years before and after sunspot minima. Only those time-intervals before sunspot minima with a significant 27-day recurrent period of the IMF sector structure and those intervals after sunspot minima with a significant 28-28.5-day recurrent period of the sector structure were used. The averaged spectra of the two Ap data sets clearly show a period of 27 days before and a period of 28–29 days after sunspot minimum. Moreover, the phase of the average semiannual wave of Ap is significantly different for the two groups of data: the Ap variation maximizes near the equinoxes during the declining phase of the sunspot cycle and near the beginning of April and October during the ascending phase of the sunspot cycle, as predicted by the Russell-McPherron (R-M) mechanism. Analysing the daily variation of ap in an analogue manner, the same equinoctial and R-M mechanisms are seen, suggesting that during phases of the solar cycle, when ap depends more on the IMF-Bs component, the R-M mechanism is predominant, whereas during phases when ap increases as v increases the equinoctial mechanism is more likely to be effective.Key words. Interplanetary physics · Magnetic fields · Solar wind plasma · Solar wind · magnetosphere interaction

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A review of the SCOSTEP’s 5-year scientific program VarSITI—Variability of the Sun and Its Terrestrial Impact

Progress in Earth and Planetary Science ◽

10.1186/s40645-021-00410-1 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Kazuo Shiokawa ◽

Katya Georgieva

Keyword(s):

Solar Wind ◽

Interplanetary Space ◽

Solar Wind Plasma ◽

The Sun ◽

Scientific Program ◽

Solar Cycles ◽

Grand Minimum ◽

The Earth ◽

Earth Connection ◽

Near Future

AbstractThe Sun is a variable active-dynamo star, emitting radiation in all wavelengths and solar-wind plasma to the interplanetary space. The Earth is immersed in this radiation and solar wind, showing various responses in geospace and atmosphere. This Sun–Earth connection variates in time scales from milli-seconds to millennia and beyond. The solar activity, which has a ~11-year periodicity, is gradually declining in recent three solar cycles, suggesting a possibility of a grand minimum in near future. VarSITI—variability of the Sun and its terrestrial impact—was the 5-year program of the scientific committee on solar-terrestrial physics (SCOSTEP) in 2014–2018, focusing on this variability of the Sun and its consequences on the Earth. This paper reviews some background of SCOSTEP and its past programs, achievements of the 5-year VarSITI program, and remaining outstanding questions after VarSITI.

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