Ulysses Observations of Latitude Gradients in the Heliospheric Magnetic Field: Radial Component and Variances

1995 ◽  
pp. 165-170 ◽  
Author(s):  
E. J. Smith ◽  
M. Neugebauer ◽  
A. Balogh ◽  
S. J. Bame ◽  
R. P. Lepping ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Radial Component ◽  
Heliospheric Magnetic Field

scholarly journals The heliospheric magnetic field and the solar wind during the solar cycle

2008 ◽  
Vol 4 (S257) ◽  
pp. 109-120 ◽  
Author(s):  
Lennard A. Fisk ◽  
Liang Zhao
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Solar Minimum ◽  
Radial Component ◽  
Heliospheric Magnetic Field ◽  
Average Value ◽  
Ram Pressure ◽  
Current Minimum ◽  
Coronal Electron

AbstractThe heliospheric magnetic field and the solar wind are behaving differently in the current solar minimum, compared to the previous minimum. The radial component of the heliospheric magnetic field, and thus the average value of the component of the solar magnetic field that opens into the heliosphere, the so-called open magnetic flux of the Sun, is lower than it was in the previous solar minimum; in fact, lower than in any previous solar minimum for which there are good spacecraft observations. The mass flux, the ram pressure, and the coronal electron temperature as measured by solar wind charge states are also lower in the current minimum compared to the previous one. This situation provides an opportunity to test some of the concepts for the behavior of the heliospheric magnetic field and the solar wind that have been developed; to improve these theories, and to construct a theory for the solar wind that accounts for the observed behavior throughout the solar cycle, including the current unusual solar minimum.

Ulysses observations of latitude gradients in the heliospheric magnetic field: Radial component and variances

1995 ◽  
Vol 72 (1-2) ◽  
pp. 165-170 ◽  
Author(s):  
E. J. Smith ◽  
M. Neugebauer ◽  
A. Balogh ◽  
S. J. Bame ◽  
R. P. Lepping ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Radial Component ◽  
Heliospheric Magnetic Field

scholarly journals Features of the Galactic Cosmic Ray Anisotropy in Solar Cycle 24 and Solar Minima 23/24 and 24/25

Solar Physics ◽  
2019 ◽  
Vol 294 (10) ◽  
Author(s):  
R. Modzelewska ◽  
K. Iskra ◽  
W. Wozniak ◽  
M. Siluszyk ◽  
M. V. Alania
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Solar Minimum ◽  
Cosmic Ray ◽  
Radial Component ◽  
Galactic Cosmic Rays ◽  
Positive Polarity ◽  
Heliospheric Magnetic Field ◽  
Solar Cycle 24 ◽  
Cycle 24

Abstract We study the role of the drift effect in the temporal changes of the anisotropy of galactic cosmic rays (GCRs) and the influence of the sector structure of the heliospheric magnetic field on it. We analyze the GCR anisotropy in Solar Cycle 24 and solar minimum 23/24 with negative polarity ($qA<0$qA<0) for the period of 2007 – 2009 and near minimum 24/25 with positive polarity ($qA>0$qA>0) in 2017 – 2018 using data of the global network of Neutron Monitors. We use the harmonic analysis method to calculate the radial and tangential components of the anisotropy of GCRs for different sectors (‘+’ corresponds to the positive and ‘−’ to the negative directions) of the heliospheric magnetic field. We compare the analysis of GCR anisotropy using different evaluations of the mean GCRs rigidity related to Neutron Monitor observations. Then the radial and tangential components are used for characterizing the GCR modulation in the heliosphere. We show that in the solar minimum 23/24 in 2007 – 2009 when $qA<0$qA<0, the drift effect is not visibly evident in the changes of the radial component, i.e. the drift effect is found to produce $\approx 4$≈4% change in the radial component of the GCR anisotropy for 2007 – 2009. Hence the diffusion dominated model of GCR transport is more acceptable in 2007 – 2009. In turn, near the solar minimum 24/25 in 2017 – 2018 when $qA>0$qA>0, the drift effect is evidently visible and produces ≈40% change in the radial component of the GCR anisotropy for 2017 – 2018. So in the period of 2017 – 2018 a diffusion model with noticeably manifested drift is acceptable. The results of this work are in good agreement with the drift theory of GCR modulation, according to which, during negative (positive) polarity cycles, a drift stream of GCRs is directed toward (away from) the Sun, thus giving rise to a 22-year cycle variation of the radial GCR anisotropy.

The Heliospheric Magnetic Field

2011 ◽  
Vol 176 (1-4) ◽  
pp. 177-215 ◽  
Author(s):  
André Balogh ◽  
Géza Erdõs
Keyword(s):  
Magnetic Field ◽  
Heliospheric Magnetic Field

scholarly journals Long-term evolution of the heliospheric magnetic field inferred from cosmogenic 44Ti activity in meteorites

2018 ◽  
Vol 610 ◽  
pp. A28 ◽  
Author(s):  
S. Mancuso ◽  
C. Taricco ◽  
P. Colombetti ◽  
S. Rubinetti ◽  
N. Sinha ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ice Cores ◽  
Long Term Evolution ◽  
Galactic Cosmic Rays ◽  
Sunspot Activity ◽  
Cosmogenic Isotopes ◽  
Heliospheric Magnetic Field ◽  
The Past ◽  
Term Evolution

Typical reconstructions of historic heliospheric magnetic field (HMF) BHMF are based on the analysis of the sunspot activity, geomagnetic data or on measurement of cosmogenic isotopes stored in terrestrial reservoirs like trees (14C) and ice cores (10Be). The various reconstructions of BHMF are however discordant both in strength and trend. Cosmogenic isotopes, which are produced by galactic cosmic rays impacting on meteoroids and whose production rate is modulated by the varying HMF convected outward by the solar wind, may offer an alternative tool for the investigation of the HMF in the past centuries. In this work, we aim to evaluate the long-term evolution of BHMF over a period covering the past twenty-two solar cycles by using measurements of the cosmogenic 44Ti activity (τ1∕2 = 59.2 ± 0.6 yr) measured in 20 meteorites which fell between 1766 and 2001. Within the given uncertainties, our result is compatible with a HMF increase from 4.87-0.30+0.24 nT in 1766 to 6.83-0.11+0.13 nT in 2001, thus implying an overall average increment of 1.96-0.35+0.43 nT over 235 years since 1766 reflecting the modern Grand maximum. The BHMF trend thus obtained is then compared with the most recent reconstructions of the near-Earth HMF strength based on geomagnetic, sunspot number, and cosmogenic isotope data.

scholarly journals A GENERALIZED DIFFUSION TENSOR FOR FULLY ANISOTROPIC DIFFUSION OF ENERGETIC PARTICLES IN THE HELIOSPHERIC MAGNETIC FIELD

2012 ◽  
Vol 750 (2) ◽  
pp. 108 ◽  
Author(s):  
F. Effenberger ◽  
H. Fichtner ◽  
K. Scherer ◽  
S. Barra ◽  
J. Kleimann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Anisotropic Diffusion ◽  
Diffusion Tensor ◽  
Energetic Particles ◽  
Heliospheric Magnetic Field
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