Multi-spacecraft Observations of interacting CME flux ropes

2020 ◽  
Author(s):  
Emilia Kilpua ◽  
Simon Good ◽  
Erika Palmerio ◽  
Eleanna Asvestari ◽  
Jens Pomoell ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Significant Interaction ◽  
Interplanetary Space ◽  
Flux Rope ◽  
The Sun ◽  
The Earth ◽  
General Importance ◽  
Solar Cycle 24 ◽  
Solar Eruptions ◽  
Cycle 24

<p>Interactions between coronal mass ejections (CMEs) in interplanetary space are a highly important aspect for understanding their physical dynamics and evolution as well as their space weather consequences. Here we present an analysis of three CMEs that erupted from the Sun on June 12-14, 2012 using almost radially aligned spacecraft at Venus and Earth, complemented by heliospheric imaging and modelling with EUHFORIA. These multi-spacecraft observations were critical for interpreting the event correctly, in particular regarding the last two CMEs in the series (June 13 and June 14). At the orbit of Venus these CMEs were mostly separate with the June 14 CME just about to reach the previous CME. A significant interaction occurred before the CMEs reached the Earth. The shock of the June 14 CME had propagated through the June 13 CME and the two CMEs had coalesced into a single large flux rope structure before they reached the Earth. This merged flux rope had one of the largest magnetic field magnitudes observed in the near-Earth solar wind during Solar Cycle 24. We discuss also the general importance of multi-spacecraft observations and modelling using them in analyzing solar eruptions.</p>

scholarly journals Predicting amplitude of solar cycle 24 based on a new precursor method

2010 ◽  
Vol 28 (2) ◽  
pp. 417-425 ◽  
Author(s):  
A. Yoshida ◽  
H. Yamagishi
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Solar Minimum ◽  
Physical Phenomenon ◽  
Late Phase ◽  
The Sun ◽  
Precursor Method ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
The Imf

Abstract. It is shown that the monthly smoothed sunspot number (SSN) or its rate of decrease during the final years of a solar cycle is correlated with the amplitude of the succeeding cycle. Based on this relationship, the amplitude of solar cycle 24 is predicted to be 84.5±23.9, assuming that the monthly smoothed SSN reached its minimum in December 2008. It is further shown that the monthly SSN in the three-year period from 2006 through 2008 is well correlated with the monthly average of the intensity of the interplanetary magnetic field (IMF). This correlation indicates that the SSN in the final years of a solar cycle is a good proxy for the IMF, which is understood to reflect the magnetic field in the corona of the sun, and the IMF is expected to be smallest at the solar minimum. We believe that this finding illuminates a physical meaning underlying the well-known precursor method for forecasting the amplitude of the next solar cycle using the aa index at the solar minimum or its average value in the decaying phase of the solar cycle (e.g. Ohl, 1966), since it is known that the geomagnetic disturbance depends strongly on the intensity of the IMF. That is, the old empirical method is considered to be based on the fact that the intensity of the coronal magnetic field decreases in the late phase of a solar cycle in parallel with the SSN. It seems that the precursor method proposed by Schatten et al. (1978) and Svalgaard et al. (2005), which uses the intensity of the polar magnetic field of the sun several years before a solar minimum, is also based on the same physical phenomenon, but seen from a different angle.

scholarly journals Statistical characteristics of geomagnetic storm activity during solar cycle 24, 2009–2020

2020 ◽  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Geomagnetic Field ◽  
Geomagnetic Storms ◽  
Radio Channel ◽  
Statistical Characteristics ◽  
The Earth ◽  
Solar Cycle 24 ◽  
Cycle 24

Urgency. The atmosphere and geospace are widely used as a radio channel in solving problems of radar, radio navigation, direction finding, radio communication, radio astronomy, and the remote sensing of the Earth from space or the near-earth environment from the surface of the planet. The parameters of the atmospheric-space radio channel are determined by the state of tropospheric and space weather, which is formed mainly by non-stationary processes on the Sun (solar storms) and partly by high-energy processes on the Earth and in the atmosphere. Geospace storms give rise to the strongest disturbances of the atmospheric-space radio channel, and it is important to note that these storms are diverse, so that no two storms are alike. At the same time, storms have both similar and individual features. Currently, there is insufficient knowledge about both of these features, and their study remains an urgent task of space geophysics and space radio physics. In particular, the identification of general patterns is advisable by performing a statistical analysis of a large number of storms. The aim of this work is to statistically analyze the parameters of the solar wind and geomagnetic field during the Solar Cycle 24 activity (2009–2020). Methods and Methodology. The parameters of the disturbed solar wind (number density nsw, velocity Vsw, and temperature Tsw), the disturbed values of the By- and Bz-components of the interplanetary magnetic field, which is the cause of magnetic storms on Earth, as well as the indices of geomagnetic activity (AE, Dst and Kp) are selected as source input to the study. In this paper, geomagnetic storms with Kр ≥ 5 or G1, G2, G3, and G4 geomagnetic storms are considered. In total, there were 153 storms with Kp ≥ 5. The time series of the nsw, Vsw, Tsw maximum values, of the By- and Bz-components, and of the AE, Dst and Kp indices, as well as of the Bz-component and the Dst index minimum values have been analyzed. Results. The main statistical characteristics of the parameters of the solar wind, interplanetary magnetic field, and of the geomagnetic field have been determined for 153 events that took place during Solar Cycle 24. Conclusions. The geomagnetic situation during Solar Cycle 24 was calmer than during Solar Cycle 23.

scholarly journals Influence of Solar Minimum on Cosmic Ray Flux, Mutations in viruses and Pandemics like COVID-19

2020 ◽  
Author(s):  
Rajagopal Kamath ◽  
Charunayan Kamath R
Keyword(s):  
Solar Minimum ◽  
Cosmic Ray ◽  
The Sun ◽  
The Earth ◽  
Solar Cycle 24 ◽  
Sun Spots ◽  
Cycle 24 ◽  
Almost All ◽  
Interdisciplinary Study ◽  
Cosmic Ray Flux

This interdisciplinary study takes into account the effect of the cosmic ray flux on mutations in viruses that result in virulent forms that lead to the occurrence of pandemics. Solar minimum, the reduction in the activity of the Sun which occurs cyclically every 11 years and deep solar minimum that occurs once in a century or so, results in increased cosmic ray flux to the Earth, which in turn generate mutations in viruses harboured in bats and other nocturnal animals. Almost all the previous pandemics occurred during solar minimum years when the Sun spots were lowest or absent and when the solar activity was at the lowest.This study suggests that the present Covid 19 pandemic is triggered by the mutated viromes in bats from latitudes above 30 degrees N. The increase in cosmic ray flux during the solar minimum of solar cycle 24 has contributed to this. It is improbable that SARS-CoV-2 emerged through laboratory manipulation of a related SARS-CoV-like coronavirus. This study indicates that SARS CoV 2 emerged as a result of biological and astrophysical processes.

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

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.

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

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.

Seasonal behavior of H component during solar cycle 24

2021 ◽  
Author(s):  
Yasmina Bouderba ◽  
Ener Aganou ◽  
Abdenaceur Lemgharbi
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Horizontal Component ◽  
Low Latitude ◽  
Seasonal Behavior ◽  
The Earth ◽  
Earth Magnetic Field ◽  
Solar Cycle 24 ◽  
Minimum Solar Activity ◽  
Cycle 24

<p>In this work we will show the behavior of the horizontal component H of the Earth Magnetic Field (EMF) along the seasons during the period of solar cycle 24 lasting from 2009 to 2019. By means of  continuous measurements of geomagnetic components (X, Y) of the EMF, we compute the horizontal component H at the Earth’s surface. The data are recorded with a time resolution of one minute at Tamanrasset observatory in Algeria at the geographical coordinates of 22.79° North and 5.53° East. These data are available from the INTERMAGNET network. We find that the variation in amplitude of the hourly average of H component at low latitude changes from a season to another and it is greater at the maximum solar activity than at the minimum solar activity.</p><p><strong>Keywords:</strong> Solar cycle 24, Season, Horizontal component H. </p>

scholarly journals Source-region characteristics of anemone active regions in the ascending phase of solar cycle 24

2020 ◽  
Vol 642 ◽  
pp. A233
Author(s):  
R. Sharma ◽  
C. Cid
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Minimum Distance ◽  
Source Region ◽  
Coronal Holes ◽  
Active Regions ◽  
Yearly Average ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Rise Phase

Context. Active regions in close proximity to coronal holes, also known as anemone regions, are the best candidates for studying the interaction between closed and open magnetic field topologies at the Sun. Statistical investigation of their source-region characteristics can provide vital clues regarding their possible association with energetic events, relevant from space weather perspectives. Aims. The main goal of our study is to understand the distinct properties of flaring and non-flaring anemone active regions and their host coronal holes, by examining spatial and magnetic field distributions during the rise phase of the solar cycle, in the years 2011–2014. Methods. Anemone regions were identified from the minimum-distance threshold, estimated using the data available in the online catalogs for on-disk active regions and coronal holes. Along with the source-region area and magnetic field characteristics, associated filament and flare cases were also located. Regions with and without flare events were further selected for a detailed statistical examination to understand the major properties of the energetic events, both eruptive and confined, at the anemone-type active regions. Results. Identified anemone regions showed weak asymmetry in their spatial distribution over the solar disk, with yearly average independent from mean sunspot number trend, during the rise phase of solar cycle 24. With the progression in solar cycle, the area and minimum-distance parameters indicated a decreasing trend in their magnitudes, while the magnetic field characteristics indicated an increase in their estimated magnitudes. More than half of the regions in our database had an association with a filament structure, and nearly a third were linked with a magnetic reconnection (flare) event. Anemone regions with and without flares had clear distinctions in their source-region characteristics evident from the distribution of their properties and density analysis. The key differences included larger area and magnetic field magnitudes for flaring anemone regions, along with smaller distances between the centers of the active region and its host coronal hole.

scholarly journals 42. Solar cosmic radiation and the interstellar magnetic field

1958 ◽  
Vol 6 ◽  
pp. 404-419 ◽  
Author(s):  
A. Ehmert
Keyword(s):  
Magnetic Field ◽  
Solar Radiation ◽  
Cosmic Radiation ◽  
The Sun ◽  
High Latitudes ◽  
Narrow Angle ◽  
The Earth ◽  
Order Of Magnitude ◽  
The Impact ◽  
Impact Zones

The increase of cosmic radiation on 23 February 1956 by solar radiation exhibited in the first minutes a high peak at European stations that were lying in direct impact zones for particles coming from a narrow angle near the sun, whilst other stations received no radiation for a further time of 10 minutes and more. An hour later all stations in intermediate and high latitudes recorded solar radiation in a distribution as would be expected if this radiation fell into the geomagnetic field in a fairly isotropic distribution. The intensity of the solar component decreased at this time at all stations according to the same hyperbolic law (~t–2).It is shown, that this decreasing law, as well as the increase of the impact zones on the earth, can be understood as the consequence of an interstellar magnetic field in which the particles were running and bent after their ejection from the sun.Considering the bending in the earth's magnetic field, one can estimate the direction of this field from the times of the very beginning of the increase in Japan and at high latitudes. The lines of magnetic force come to the earth from a point with astronomical co-ordinates near 12·00, 30° N. This implies that within the low accuracy they have the direction of the galactic spiral arm in which we live. The field strength comes out to be about 0·7 × 10–6gauss. There is a close agreement with the field, that Fermi and Chandrasekhar have derived from Hiltner's measurements of the polarization of starlight and the strength of which they had estimated to the same order of magnitude.

X-Ray Flares and Activity Complexes on the Sun in Solar Cycle 24

2020 ◽  
Vol 64 (1) ◽  
pp. 58-65 ◽  
Author(s):  
E. S. Isaeva ◽  
V. M. Tomozov ◽  
S. A. Yazev
Keyword(s):  
Solar Cycle ◽  
The Sun ◽  
X Ray ◽  
Solar Cycle 24 ◽  
Cycle 24
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