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The dependence of the sources and properties of the near-Earth solar wind on solar cycle activity is an important issue in solar and space physics. We use the improved two-step mapping procedure that takes into account the initial…

Solar and Stellar Astrophysics · Physics 2024-07-02 Xinzheng Shi , Hui Fu , Zhenghua Huang , Limei Yan , Chi Ma , Chenxi Huangfu , Hongqiang Song , Lidong Xia

The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, $\epsilon_{N} \equiv \Delta{N}/N$) is of vital importance in understanding several problems in heliospheric physics…

Solar and Stellar Astrophysics · Physics 2015-06-22 Susanta Kumar Bisoi , P. Janardhan , M. Ingale , P. Subramanian , S. Ananthakrishnan , M. Tokumaru , K. Fujiki

In the present paper a systematic study is carried out to validate the similarity or degree of relationship between daily terrestrial cosmic rays intensity and three characteristics of about evolution of solar corona, like a number of…

Solar and Stellar Astrophysics · Physics 2019-06-05 D. Sierra-Porta

The sunspot area fluctuations for the northern and the southern hemispheres of the Sun over the epoch of 12 cycles (12-23) are investigated. Because of the asymmetry of their probability distributions, the positive and the negative…

Applications · Statistics 2015-05-19 R. Getko

We investigate the characteristics and the sources of the slow (< 450 km/s) solar wind during the four years (2006-2009) of low solar activity between Solar Cycles 23 and 24. We use a comprehensive set of in-situ observations in the…

Solar and Stellar Astrophysics · Physics 2016-10-05 E. K. J. Kilpua , M. S. Madjarska , N. Karna , T. Wiegelmann , C. Farrugia , W. Yu , K. Andreeova

We investigate possible links between the large-scale and small-scale features of solar wind fluctuations across the frequency break separating fluid and kinetic regimes. The aim is to correlate the magnetic field fluctuations polarization…

Space Physics · Physics 2017-01-26 D. Telloni , R. Bruno

To measure the floor in interplanetary magnetic field and estimate the time- invariant open magnetic flux of Sun, it is necessary to know a part of magnetic field of Sun carried away by CMEs. In contrast with previous papers, we did not use…

Solar and Stellar Astrophysics · Physics 2009-11-19 Yu. I. Yermolaev , I. G. Lodkina , N. S. Nikolaeva , M. Yu. Yermolaev

We use ACE/SWICS elemental composition data to compare the variations in solar wind fractionation as measured by SWICS during the last solar maximum (1999-2001), the solar minimum (2006-2009) and the period in which the Genesis spacecraft…

Solar and Stellar Astrophysics · Physics 2015-10-14 P. Pilleri , D. B. Reisenfeld , T. H. Zurbuchen , S. T. Lepri , P. Shearer , J. A. Gilbert , R. von Steiger , R. C. Wiens

To investigate the power and spectral index anisotropy in the inertial range of solar wind turbulence, we use 70 intervals of electric field data accumulated by Cluster spacecraft in the free solar wind. We compute the electric field…

Space Physics · Physics 2020-09-24 Deepali , Supratik Banerjee

Interplanetary magnetic field magnitude fluctuations are notoriously more intermittent than velocity fluctuations in both fast and slow wind. This behaviour has been interpreted in terms of the anomalous scaling observed in passive scalars…

We present and discuss the strong correspondence between evolution of the emission length scale in the lower transition region and in situ measurements of the fast solar wind composition during this most recent solar minimum. We combine…

Solar and Stellar Astrophysics · Physics 2015-05-30 Scott W. McIntosh , Kandace K. Kiefer , Robert J. Leamon , Justin C. Kasper , Michael S. Stevens

We have studied the relationship between the solar-wind speed $[V]$ and the coronal magnetic-field properties (a flux expansion factor [$f$] and photospheric magnetic-field strength [$B_{\mathrm{S}}$]) at all latitudes using data of…

Solar and Stellar Astrophysics · Physics 2015-08-19 Ken'ichi Fujiki , Munetoshi Tokumaru , Tomoya Iju , Kazuyuki Hakamada , Masayoshi Kojima

Magnetic fluctuations in the solar wind are often observed to maintain constant magnitude of the magnetic field in a manner consistent with spherically-polarized large-amplitude Alfv\'en waves. We investigate the effect of spherical…

Solar and Stellar Astrophysics · Physics 2023-11-17 Corina Dunn , Trevor Bowen , Alfred Mallet , Samuel Badman , Stuart Bale

Using data collected by the Indian Mars Orbiter Mission in October 2021, we investigated coronal regions of the Sun by analyzing the Doppler spectral width of radio signals to estimate solar wind velocity. A simplified equation is…

Solar and Stellar Astrophysics · Physics 2025-04-02 Keshav Aggarwal , R. K. Choudhary , Abhirup Datta , Roopa M. V. , Bijoy K. Dai

We study scaling in fluctuations of the geomagnetic indices (AE, AU, and AL) that provide a measure of magnetospheric activity and of the epsilon parameter which is a measure of the solar wind driver. Generalized structure function (GSF)…

Space Physics · Physics 2015-06-26 B. Hnat , S. C. Chapman , G. Rowlands , N. W. Watkins , M. P. Freeman

We investigate Venus Express (VEX) observations of magnetic field fluctuations performed systematically in the solar wind at 0.72 Astronomical Units (AU), between 2007 and 2009, during the deep minimum of the solar cycle 24. The Power…

Understanding the irregular variation of the solar cycle is crucial due to its significant impact on global climates and the heliosphere. Since the polar magnetic field determines the amplitude of the next solar cycle, variations in the…

Solar and Stellar Astrophysics · Physics 2024-12-25 Pawan Kumar

The minimum of solar cycle 24 is significantly different from most other minima in terms of its duration as well as its abnormally low levels of activity. Using available helioseismic data that cover epochs from the minimum of cycle 23 to…

Solar and Stellar Astrophysics · Physics 2015-05-19 H. M. Antia , Sarbani Basu

A statistical relationship between magnetic reconnection, current sheets and intermittent turbulence in the solar wind is reported for the first time using in-situ measurements from the Wind spacecraft at 1 AU. We identify intermittency as…

Space Physics · Physics 2015-06-19 K. T. Osman , W. H. Matthaeus , J. T. Gosling , A. Greco , S. Servidio , B. Hnat , S. C. Chapman , T. D. Phan

We present the first survey of electric field data using the ARTEMIS spacecraft in the solar wind to study inertial range turbulence. It was found that the average perpendicular spectral index of the electric field depends on the frame of…

Space Physics · Physics 2012-08-20 C. H. K. Chen , S. D. Bale , C. Salem , F. S. Mozer