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M. V. Alania - One of the best experts on this subject based on the ideXlab platform.
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rigidity dependence of the long term variations of galactic cosmic ray intensity in relation to the interplanetary magnetic field turbulence 1968 2002
Solar Physics, 2014Co-Authors: M Siluszyk, K Iskra, M. V. AlaniaAbstract:We studied the relationship between the power-law exponent γ on the rigidity R of the spectrum of galactic cosmic-ray (GCR) intensity variation (δD(R)/D(R)∝R−γ) and the exponents νy and νz of the power spectral density (PSD) of the By and Bz components of the interplanetary magnetic field (IMF) turbulence (PSD∼f−ν, where f is the frequency). We used the data from neutron monitors and IMF for the period of 1968 – 2002. The exponents νy and νz were calculated in the frequency interval Δf=f2−f1=3×10−6 Hz of the resonant frequencies (f1=1×10−6 Hz, f2=4×10−6 Hz) that are responsible for the scattering of GCR particles with the rigidity range detected by neutron monitors. We found clear inverse correlations between γ and νy or νz when the time variations of the resonant frequencies were derived from in situ measurements of the Solar Wind Velocity Usw and IMF strength B during 1968 – 2002. We argue that these inverse relations are a fundamental feature in the GCR modulation that is not restricted to the analyzed years of 1968 – 2002.
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On the relationship of the 27-day variations of the Solar Wind Velocity and galactic cosmic ray intensity in minimum epoch of Solar activity
Solar Physics, 2011Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:We study the relationship of the 27-day variation of the galactic cosmic ray intensity with similar changes of the Solar Wind Velocity and the interplanetary magnetic field based on the experimental data for the Bartels rotation period 2379 of 23 November 2007-19 December 2007. We develop a three dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwells equations with a heliolongitudinally dependent 27-day variation of the Solar Wind Velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity - (1) with a plane heliospheric neutral sheet, and (2)- with the sector structure of the interplanetary magnetic field. The theoretical calculation shows that the sector structure does not influence significantly on the 27-day variation of galactic cosmic ray intensity as it was shown before based on the experimental data. Also a good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (correlation coefficient equals 0.98 0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter z (correlation coefficient equals -0.91 0.05) which is proportional to the product of the Solar Wind Velocity V and the strength of the interplanetary magnetic field B (z VB). The high anticorrelation between these quantities indicates that the predictable 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect.
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on the relationship of the 27 day variations of the Solar Wind Velocity and galactic cosmic ray intensity in minimum epoch of Solar activity
Solar Physics, 2011Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:We study the relationship of the 27-day variations of the galactic cosmic ray intensity with similar variations of the Solar Wind Velocity and the interplanetary magnetic field based on observational data for the Bartels rotation period # 2379 of 23 November 2007 – 19 December 2007. We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwell’s equations with a heliolongitudinally dependent 27-day variation of the Solar Wind Velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity, i) with a plane heliospheric neutral sheet, and ii) with the sector structure of the interplanetary magnetic field. The theoretical calculations show that the sector structure does not significantly influence the 27-day variation of galactic cosmic ray intensity, as had been shown before, based on observational data. Furthermore, good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (with a correlation coefficient of 0.98±0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter ζ (with a correlation coefficient of −0.91±0.05), which is proportional to the product of the Solar Wind Velocity V and the strength of the interplanetary magnetic field B (ζ∼VB). The high anticorrelation between these quantities indicates that the predicted 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect.
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modeling and experimental study of the 27 day variation of galactic cosmic ray intensity for a Solar Wind Velocity depending on heliolongitude
Advances in Space Research, 2010Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:Abstract We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic-ray (GCR) intensity with a spatial variation of the Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving the corresponding Maxwell equations with a variable Solar Wind speed, which reproduces in situ observed experimental data for the time interval to be analyzed (24 August 2007–28 February 2008). We perform model calculations for the GCR intensity using the variable Solar Wind and the corresponding magnetic field. Results are compatible with experimental data; the correlation coefficient between our model predictions and observed 27-day GCR variation is 0.80 ± 0.05.
Anna Wawrzynczak - One of the best experts on this subject based on the ideXlab platform.
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On the relationship of the 27-day variations of the Solar Wind Velocity and galactic cosmic ray intensity in minimum epoch of Solar activity
Solar Physics, 2011Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:We study the relationship of the 27-day variation of the galactic cosmic ray intensity with similar changes of the Solar Wind Velocity and the interplanetary magnetic field based on the experimental data for the Bartels rotation period 2379 of 23 November 2007-19 December 2007. We develop a three dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwells equations with a heliolongitudinally dependent 27-day variation of the Solar Wind Velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity - (1) with a plane heliospheric neutral sheet, and (2)- with the sector structure of the interplanetary magnetic field. The theoretical calculation shows that the sector structure does not influence significantly on the 27-day variation of galactic cosmic ray intensity as it was shown before based on the experimental data. Also a good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (correlation coefficient equals 0.98 0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter z (correlation coefficient equals -0.91 0.05) which is proportional to the product of the Solar Wind Velocity V and the strength of the interplanetary magnetic field B (z VB). The high anticorrelation between these quantities indicates that the predictable 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect.
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on the relationship of the 27 day variations of the Solar Wind Velocity and galactic cosmic ray intensity in minimum epoch of Solar activity
Solar Physics, 2011Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:We study the relationship of the 27-day variations of the galactic cosmic ray intensity with similar variations of the Solar Wind Velocity and the interplanetary magnetic field based on observational data for the Bartels rotation period # 2379 of 23 November 2007 – 19 December 2007. We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwell’s equations with a heliolongitudinally dependent 27-day variation of the Solar Wind Velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity, i) with a plane heliospheric neutral sheet, and ii) with the sector structure of the interplanetary magnetic field. The theoretical calculations show that the sector structure does not significantly influence the 27-day variation of galactic cosmic ray intensity, as had been shown before, based on observational data. Furthermore, good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (with a correlation coefficient of 0.98±0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter ζ (with a correlation coefficient of −0.91±0.05), which is proportional to the product of the Solar Wind Velocity V and the strength of the interplanetary magnetic field B (ζ∼VB). The high anticorrelation between these quantities indicates that the predicted 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect.
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modeling and experimental study of the 27 day variation of galactic cosmic ray intensity for a Solar Wind Velocity depending on heliolongitude
Advances in Space Research, 2010Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:Abstract We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic-ray (GCR) intensity with a spatial variation of the Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving the corresponding Maxwell equations with a variable Solar Wind speed, which reproduces in situ observed experimental data for the time interval to be analyzed (24 August 2007–28 February 2008). We perform model calculations for the GCR intensity using the variable Solar Wind and the corresponding magnetic field. Results are compatible with experimental data; the correlation coefficient between our model predictions and observed 27-day GCR variation is 0.80 ± 0.05.
G D Reeves - One of the best experts on this subject based on the ideXlab platform.
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long term variations in Solar Wind Velocity and radiation belt electrons
Journal of Geophysical Research, 2013Co-Authors: G D Reeves, Steve Morley, G S CunninghamAbstract:[1] In this paper we analyze the relationship between yearly variations in MeV radiation belt electron fluxes and Solar Wind Velocity (Vsw). We find that the long-term trends have properties that are important for physical understanding of Solar Wind-magnetosphere coupling processes and, potentially, for improvements of short-term space weather forecasts. A statistical analysis of Solar Wind Velocity shows that years with high average Solar Wind Velocity are not high simply due to a larger number of days with high Vsw. Rather the entire distribution (median and percentiles) shifts along with the mean Vsw. Similar behavior is seen in the MeV geosynchronous electron fluxes. By subtracting out a 365 day running average baseline, we show that the distribution of log fluxes around the mean is remarkably stable from year to year within a Solar cycle and from one Solar cycle to another. In contrast, the long-term trends in the baseline show significant changes from year to year and from one Solar cycle to another suggesting that Solar Wind coupling to radiation belt fluxes is not constant but varies over long, as well as short, time scales. In some epicycles, the mean flux is strongly dependent on Vsw while in others the dependence is weak. Similarly, a given average Vsw may produce high average fluxes in one epicycle and low average fluxes in another. Future study of these epicycles and the relative variations within them may improve both physical understanding of Solar Wind-magnetosphere coupling and space weather forecasting.
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on the relationship between relativistic electron flux and Solar Wind Velocity paulikas and blake revisited
Journal of Geophysical Research, 2011Co-Authors: G D Reeves, S K Morley, R H W Friedel, M G Henderson, T E Cayton, Gregory S Cunningham, Bernard J Blake, Rod A Christensen, Davis ThomsenAbstract:[1] Thirty years ago Paulikas and Blake (1979) showed a remarkable correlation between geosynchronous relativistic electron fluxes and Solar Wind speed (Vsw). This seminal result has been a foundation of radiation belt studies, space weather forecasting, and current understanding of Solar Wind radiation belt coupling. We have repeated their analysis with a considerably longer-running data set (1989–2010) from the Los Alamos National Laboratory energetic particle instruments with several surprising results. Rather than the roughly linear correlation between Vsw and log (flux), our results show a triangle-shaped distribution in which fluxes have a distinct Velocity-dependent lower limit but a Velocity-independent upper limit. The highest-electron fluxes can occur for any value of Vsw with no indication of a Vsw threshold. We also find a distinct Solar cycle dependence with the triangle-shaped distribution evident in 2 declining phase years dominated by high-speed streams but essentially no correlation in 2 Solar maximum years. For time periods that do show a triangle-shaped distribution we consider whether it can be explained by scatter due to other parameters. We examine the role of time dependence and time lag in producing the observed distribution. We also look at the same statistical relationship but at energies ≪1 MeV. We conclude that the relationship between radiation belt electron fluxes and Solar Wind Velocity is substantially more complex than suggested by previous statistical studies. We find that there are important ways in which the “conventional wisdom” stating that high-Velocity Wind drives high-MeV electron fluxes is, in general, either misleading or unsupported.
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quantitative prediction of radiation belt electrons at geostationary orbit based on Solar Wind measurements
Geophysical Research Letters, 2001Co-Authors: X Li, M Temerin, G D Reeves, D N Baker, D.e. LarsonAbstract:Solar Wind measurements are used to predict the MeV electron radiation belt flux at the position of geostationary orbit. Using a model based on the standard radial diffusion equation, a prediction efficiency of 0.81 and a linear correlation of 0.90 were achieved for the years 1995–1996 for the logarithm of average daily flux. Model parameters based on the years 1995-1996 gave a prediction efficiency and a linear correlation for the years 1995–1999 of 0.59 and 0.80, respectively. The radial diffusion equation is solved after making the diffusion coefficient a function of the Solar Wind Velocity and interplanetary magnetic field. The Solar Wind Velocity is the most important parameter governing relativistic electron fluxes at geostationary orbit. The model also provides a physical explanation to several long standing mysteries of the variation of the MeV electrons.
W Feng - One of the best experts on this subject based on the ideXlab platform.
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characteristics of Solar Wind rotation
arXiv: Solar and Stellar Astrophysics, 2019Co-Authors: Kejun Li, W FengAbstract:Over 54 years of hourly mean value of Solar Wind Velocity from 27 Nov. 1963 to 31 Dec. 2017 are used to investigate characteristics of the rotation period of Solar Wind through auto-correlation analysis. Solar Wind of high Velocity is found to rotate faster than low-Velocity Wind, while its rotation rate increases with Velocity increasing, but in contrast for Solar Wind of low Velocity, its rotation rate decreases with Velocity increasing. Our analysis shows that Solar Wind of a higher Velocity statistically possesses a faster rotation rate for the entire Solar Wind. The yearly rotation rate of Solar Wind Velocity does not follow the Schwable cycle, but it is significantly negatively correlated to yearly sunspot number when it leads by 3 years. Physical explanations are proposed to these findings.
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periodicity for 50 yr of daily Solar Wind Velocity
Monthly Notices of the Royal Astronomical Society, 2017Co-Authors: J Zhang, W FengAbstract:Daily mean Velocity of Solar Wind that was surveyed near the Earth's orbit at about 1 au from 1963 November 27 to 2015 November 30 and issued by OMNIWeb is used to look into its periodicity through the Lomb-Scargle periodogram method. As the strongest periodical signal, the Solar activity cycle of about 10.4 yr is found in high-Velocity Wind, but in low-Velocity Wind, the 9.17-yr cycle appears instead. The rotation cycle of about 27 d and its 1/2 and 1/3 harmonic periods are clearly detected in all-, low-and high-Velocity Wind, and at their periodograms, several individual periodical peaks appear very close to the peaks of these three periods. The annual period of about 1.07 yr is identified for both all-and low-Velocity Wind, but not for high-Velocity Wind after 1994. The 1.68-yr period occurs in all-and high-Velocity Wind, but does not appear in low-Velocity Wind. The period of about 2.42 yr appears just in the all-Velocity Wind after 1994, but its twofold period (about 4.83 yr) appears in both all-and high-Velocity Wind. The period of about 4.1 yr occurs in all-, low- and high-Velocity Wind. The possible origin of these periods is discussed.
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a statistical analysis of 50 years of daily Solar Wind Velocity data
The Astronomical Journal, 2016Co-Authors: J Zhanng, W FengAbstract:Daily mean value of Solar Wind Velocity measured by various spacecraft near the Earth's orbit from 1963 November 27 to 2013 December 31 given by OMNIWeb is utilized to investigate its characteristics through statistical analyses. The percent probability distribution of Solar Wind Velocity can be described well by the Γ distribution function with the most probable Velocity to be . It is found that Solar Wind could be statistically classified into three groups: (1) the low-Velocity Wind, , which positively responds to, and in the cycle phase lags, the Solar activity cycle; (2) the high-Velocity Wind, , which negatively responds to, and in the cycle phase leads, the Solar activity cycle, but in a short timescale (one-rotation-period) lags the Solar activity cycle; and (3) the extreme-high-Velocity Wind, , which positively responds to, and in cycle phase leads, the Solar activity cycle. A period of about 27 days is determined for Solar Wind in the first two groups, so that Solar Wind in the groups is modulated by the Solar rotation and related with Solar long-life magnetic structures. Solar Wind of extreme high Velocity appears mainly at the descending phases of the Solar cycles.
Renata Modzelewska - One of the best experts on this subject based on the ideXlab platform.
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On the relationship of the 27-day variations of the Solar Wind Velocity and galactic cosmic ray intensity in minimum epoch of Solar activity
Solar Physics, 2011Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:We study the relationship of the 27-day variation of the galactic cosmic ray intensity with similar changes of the Solar Wind Velocity and the interplanetary magnetic field based on the experimental data for the Bartels rotation period 2379 of 23 November 2007-19 December 2007. We develop a three dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwells equations with a heliolongitudinally dependent 27-day variation of the Solar Wind Velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity - (1) with a plane heliospheric neutral sheet, and (2)- with the sector structure of the interplanetary magnetic field. The theoretical calculation shows that the sector structure does not influence significantly on the 27-day variation of galactic cosmic ray intensity as it was shown before based on the experimental data. Also a good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (correlation coefficient equals 0.98 0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter z (correlation coefficient equals -0.91 0.05) which is proportional to the product of the Solar Wind Velocity V and the strength of the interplanetary magnetic field B (z VB). The high anticorrelation between these quantities indicates that the predictable 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect.
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on the relationship of the 27 day variations of the Solar Wind Velocity and galactic cosmic ray intensity in minimum epoch of Solar activity
Solar Physics, 2011Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:We study the relationship of the 27-day variations of the galactic cosmic ray intensity with similar variations of the Solar Wind Velocity and the interplanetary magnetic field based on observational data for the Bartels rotation period # 2379 of 23 November 2007 – 19 December 2007. We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic ray intensity based on the heliolongitudinally dependent Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving Maxwell’s equations with a heliolongitudinally dependent 27-day variation of the Solar Wind Velocity reproducing in situ observations. We consider two types of 3-D models of the 27-day variation of galactic cosmic ray intensity, i) with a plane heliospheric neutral sheet, and ii) with the sector structure of the interplanetary magnetic field. The theoretical calculations show that the sector structure does not significantly influence the 27-day variation of galactic cosmic ray intensity, as had been shown before, based on observational data. Furthermore, good agreement is found between the time profiles of the theoretically expected and experimentally obtained first harmonic waves of the 27-day variation of the galactic cosmic ray intensity (with a correlation coefficient of 0.98±0.02). The expected 27-day variation of the galactic cosmic ray intensity is inversely correlated with the modulation parameter ζ (with a correlation coefficient of −0.91±0.05), which is proportional to the product of the Solar Wind Velocity V and the strength of the interplanetary magnetic field B (ζ∼VB). The high anticorrelation between these quantities indicates that the predicted 27-day variation of the galactic cosmic ray intensity mainly is caused by this basic modulation effect.
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modeling and experimental study of the 27 day variation of galactic cosmic ray intensity for a Solar Wind Velocity depending on heliolongitude
Advances in Space Research, 2010Co-Authors: M. V. Alania, Renata Modzelewska, Anna WawrzynczakAbstract:Abstract We develop a three-dimensional (3-D) model of the 27-day variation of galactic cosmic-ray (GCR) intensity with a spatial variation of the Solar Wind Velocity. A consistent, divergence-free interplanetary magnetic field is derived by solving the corresponding Maxwell equations with a variable Solar Wind speed, which reproduces in situ observed experimental data for the time interval to be analyzed (24 August 2007–28 February 2008). We perform model calculations for the GCR intensity using the variable Solar Wind and the corresponding magnetic field. Results are compatible with experimental data; the correlation coefficient between our model predictions and observed 27-day GCR variation is 0.80 ± 0.05.