scholarly journals Long-term evolution in the global distribution of solar wind speed and density fluctuations during 1997-2009

2012 ◽  
Vol 117 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Munetoshi Tokumaru ◽  
Masayoshi Kojima ◽  
Ken'ichi Fujiki
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Long Term Evolution ◽  
Density Fluctuations ◽  
Global Distribution ◽  
Term Evolution

Global Distribution of the Solar Wind Speed Reconstructed from Improved Tomographic Analysis of Interplanetary Scintillation Observations between 1985 and 2019

2021 ◽  
Vol 922 (1) ◽  
pp. 73
Author(s):  
Munetoshi Tokumaru ◽  
Ken’ichi Fujiki ◽  
Masayoshi Kojima ◽  
Kazumasa Iwai
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Power Index ◽  
Solar Wind Speed ◽  
Global Distribution ◽  
Interplanetary Scintillation ◽  
Wind Speeds ◽  
In Situ Observations

Abstract Computer-assisted tomography (CAT) for interplanetary scintillation (IPS) observations enables the determination of the global distribution of solar wind speed. We compared solar wind speeds derived from the CAT analysis of IPS observations between 1985 and 2019 with in situ observations conducted by the near-Earth and Ulysses spacecraft. From this comparison, we found that solar wind speeds from the IPS observations for 2009–2019 were systematically higher than the in situ observations, whereas those for the period until 2008 were in good agreement with the in situ observations. Further, we found that the discrepancy between IPS and the in situ observations is improved by changing the power index of the empirical relation between the solar wind speed and density fluctuations. The CAT analysis using an optimal value for the power index determined from the comparison between IPS and in situ observations revealed long-term variations in the solar wind speed distribution over three cycles, leading to a better understanding of the time-varying global heliosphere. We found that polar solar winds become highly anisotropic at the Cycle 24/25 minimum, which is a peculiar aspect of this minimum. The IPS observations showed general agreement with the Parker Solar Probe observations around the perihelion of Orbit 1; this supports the reliability of the CAT analysis. The results of this study suggest that the physical properties of solar wind microturbulence may vary with a long-term decline in the solar activity, which provides important implication on the solar wind acceleration.

North-south asymmetry in global distribution of the solar wind speed during 1985-2013

2015 ◽  
Vol 120 (5) ◽  
pp. 3283-3296 ◽  
Author(s):  
Munetoshi Tokumaru ◽  
Ken'ichi Fujiki ◽  
Tomoya Iju
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Global Distribution ◽  
South Asymmetry

Long-term enhancements in solar wind speed

1996 ◽  
Vol 101 (A1) ◽  
pp. 415-424 ◽  
Author(s):  
P. R. Gazis
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Solar Wind Speed

On the high correlation between long-term averages of solar wind speed and geomagnetic activity

1977 ◽  
Vol 82 (13) ◽  
pp. 1933-1937 ◽  
Author(s):  
N. U. Crooker ◽  
J. Feynman ◽  
J. T. Gosling
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Geomagnetic Activity ◽  
Solar Wind Speed

scholarly journals Experimental and Theoretical Study of Radiometeors

1980 ◽  
Vol 90 ◽  
pp. 133-136
Author(s):  
Jean Delcourt
Keyword(s):  
Solar Wind ◽  
Wind Erosion ◽  
Theoretical Study ◽  
Long Term Evolution ◽  
Experimental Results ◽  
Dynamical Study ◽  
Long Period ◽  
The Earth ◽  
Term Evolution

We study the long-term evolution of the orbits of meteoric particles subjected to planetary perturbations and to Poynting-Robertson drag. Solar wind erosion of the particle is considered. We compute the long-period elliptic elements of the meteoric orbit when it intersects the orbit of the Earth. We compare experimental results with those of the dynamical study.

Structure in the Solar Corona from Radio Scintillation Measurements

1996 ◽  
Vol 154 ◽  
pp. 97-104
Author(s):  
Richard Woo
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Recent Progress ◽  
Solar Wind Speed ◽  
Source Region ◽  
Density Fluctuations ◽  
The Sun ◽  
Fine Scale ◽  
Radio Scintillation ◽  
Electron Density Fluctuations

AbstractSince the 1950s, a wide variety of radio observations based on scattering by electron density fluctuations in the solar wind has provided much of our information on density fluctuations and solar wind speed near the source region of the solar wind. This paper reviews recent progress in the understanding of the nature of these density fluctuations and their relationship to features on the Sun. The results include the first measurements of fine-scale structure within coronal streamers and evidence for structure in solar wind speed in the inner corona.

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