Cosmic ray heliospheric transport study with neutron monitor data

Ahluwalia, H. S.; Ygbuhay, R. C.; Modzelewska, Renata; Дорман, Л. И.; Alania, M. V.

doi:10.1002/2015ja021603

Cited by 17 publications

(10 citation statements)

References 74 publications

(156 reference statements)

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“…Here we present the time variation of the GCR anisotropy for Oulu NM (as an example) through almost the whole Solar Cycle 24, 2007 -2018. We compare the values of the amplitude, phase, radial and azimuthal components of the GCR anisotropy using two approaches: median R m (Ahluwalia et al, 2015) and effective R ef (Gil et al, 2017) rigidity of response. The errors for annual values are estimated as the standard deviation from monthly data.…”

Section: Resultsmentioning

confidence: 99%

“…We use the hourly data of GCRs intensity for NMs with geomagnetic cut-off rigidities Rc < 5 GV. For calculation of the GCR anisotropy we follow the procedure from (Modzelewska and Alania, 2018;Ahluwalia et al, 2015). Details of the NMs and parameters used for calculations are presented in Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…In this paper we compare the analysis of the GCR anisotropy using this two approaches: the median rigidity R m of NM response (Ahluwalia et al, 2015;Ahluwalia and Fikani, 2007) and the effective rigidity R ef characteristic for each NM proposed by (Gil et al, 2017;Asvestari et al, 2017).…”

Section: Methodsmentioning

confidence: 99%

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

Modzelewska

Iskra

Wozniak³

et al. 2019

Sol Phys

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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) for the period of 2007-2009 and near minimum 24/25 with positive polarity (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, the drift effect is not visibly evident in the changes of the radial component, i.e. the drift effect is found to produce ≈ 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, 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.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

Modzelewska

Iskra

Wozniak³

et al. 2019

Sol Phys

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“…They compute radiation dose based on estimated values of the solar modulation potential (F) derived by Gleeson and Axford (1968) invoking a spherical symmetry of the Parker equation (1965). Ahluwalia et al (2015) show that use of F does not explain empirical results of their analyses of neutron monitor data from global network (Rm ~ 20 GV); so their estimates of the radiation dose increase should be treated with caution.…”

Section: Featuresmentioning

confidence: 96%

Holistic study of space weather and space climate: 1700- 2018

Ahluwalia¹

2019

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019)

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We present an update of changes in space weather/space climate at Earth orbit using sunspot number (SSN) timeline (1700-2018), geomagnetic indices aa/Ap (1870-2018), solar polar magnetic field (1976-2017), interplanetary magnetic field (IMF) and galactic cosmic ray (GCR) flux (1963-2018) in the stratosphere at high latitudes. The Cycle 24 is close to minimum, expected in 2020. The baseline of aa index increases monotonically from 1900 to 1986 declining steeply afterwards, solar polar magnetic field decreases systematically for last three cycles (22-24) as do SSNs at cycle peaks. Livingston and Penn (2009) note a long term weakening of maximum magnetic field in sunspots since 1992. They expect SSNs for the Cycle 25 to peak at 7 (a steep decline in solar activity) leading to Maunder-like minimum, in contrast to prediction of a Dalton minimum by several colleagues. The North-South asymmetry in the solar polar field is pronounced for the decay phase of cycles 23, 24, itseems to change sign after the Cycle 21. GCR flux in the stratosphere is higher than in 1965 and increasing, pointing to an enhanced radiation exposure in future for passengers on transpolar flights, the astronauts on the space station as well as those travelling to and staying on the Moon and the Mars on prolonged missions; the assets in space would have to be hardened for safety from enhanced radiation.

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“…Of recent publications devoted to the GCR anisotropy, we mention, for example, Kudela & Sabbah (2016), Ahluwalia et al 2015, Sabbah (2013), and Oh et al 2010. However, quasi-periodic changes of the GCR anisotropy connected with the solar rotation (called the 27-day variation here) were studied rarely until Alania et al (2005Alania et al ( , 2008 examined the ecliptic plane anisotropy (2D case) and the north-south component alone for polar-located NMs was considered by Owens et al (1980).…”

Section: Introductionmentioning

confidence: 99%

Quasi-periodic changes in the 3D solar anisotropy of Galactic cosmic rays for 1965–2014

Modzelewska

Alania

2017

A&A

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Aims. We study features of the 3D solar anisotropy of Galactic cosmic rays (GCR) for 1965−2014 (almost five solar cycles, cycles 20−24). We analyze the 27-day variations of the 2D GCR anisotropy in the ecliptic plane and the north-south anisotropy normal to the ecliptic plane. We study the dependence of the 27-day variation of the 3D GCR anisotropy on the solar cycle and solar magnetic cycle. We demonstrate that the 27-day variations of the GCR intensity and anisotropy can be used as an important tool to study solar wind, solar activity, and heliosphere. Methods. We used the components Ar, Aϕ and At of the 3D GCR anisotropy that were found based on hourly data of neutron monitors (NMs) and muon telescopes (MTs) using the harmonic analyses and spectrographic methods. We corrected the 2D diurnal (~24-h) variation of the GCR intensity for the influence of the Earth magnetic field. We derived the north-south component of the GCR anisotropy based on the GG index, which is calculated as the difference in GCR intensities of the Nagoya multidirectional MTs. Results. We show that the behavior of the 27-day variation of the 3D anisotropy verifies a stable long-lived active heliolongitude on the Sun. This illustrates the usefulness of the 27-day variation of the GCR anisotropy as a unique proxy to study solar wind, solar activity, and heliosphere. We distinguish a tendency of the 22-yr changes in amplitude of the 27-day variation of the 2D anisotropy that is connected with the solar magnetic cycle. We demonstrate that the amplitudes of the 27-day variation of the north-south component of the anisotropy vary with the 11-yr solar cycle, but a dependence of the solar magnetic polarity can hardly be recognized. We show that the 27-day recurrences of the GG index and the At component are highly positively correlated, and both are highly correlated with the By component of the heliospheric magnetic field.

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Cosmic ray heliospheric transport study with neutron monitor data

Cited by 17 publications

References 74 publications

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

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

Holistic study of space weather and space climate: 1700- 2018

Quasi-periodic changes in the 3D solar anisotropy of Galactic cosmic rays for 1965–2014

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