Solar cycle dependence of global distribution of solar wind speed

Kojima, M.; Kakinuma, Takakiyo

doi:10.1007/bf00212754

Cited by 162 publications

(114 citation statements)

References 31 publications

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“…Modern slow solar-wind velocities are very seldom below 250 km s )1 (Kojima and Kakinuma, 1990). This value is around 1.3 and 1.1 times higher than the calculated average Maunder-minimum wind velocities.…”

Section: Discussionmentioning

confidence: 99%

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Geomagnetic activity and wind velocity during the Maunder minimum

Mendoza

1997

Ann. Geophys.

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Abstract. Following a given classi®cation of geomagnetic activity, we obtained aa index values for the Maunder minimum (1645±1715). It is found that the recurrent and¯uctuating activities were not appreciable and that the shock activity levels were very low. The aa index level was due almost entirely to the quiet days. Calculated average solar-wind velocities were 194.3 km s )1 from 1657 to 1700 and 218.7 km s )1 from 1700 onwards. Also, the coronal magnetic ®eld magnitude and southward interplanetary magnetic ®eld component Bz were lower. It is concluded that the nearly absent levels of geomagnetic activity during this period were due to lower coronal and Bz magnetic ®eld magnitudes as well as to the continuous impinging on the Earth of a slow wind.

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Section: Discussionmentioning

confidence: 99%

“…Therefore during these periods the Earth is frequently inside the neutral sheet. At the neutral sheet the wind speed falls o and reaches a minimum (Bruno et al, 1986;Kojima and Kakinuma, 1990). Moreover, the thickness of the slow-wind sheet depends upon the intensity of the solar dipole.…”

Section: The Magnetic ®Eldmentioning

confidence: 99%

Geomagnetic activity and wind velocity during the Maunder minimum

Mendoza

1997

Ann. Geophys.

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“…In the early 1970s researchers at the University of California at San Diego used a system of three scintillation arrays (Coles and Kaufman, 1978) to derive solar wind velocities by watching the intensity scintillation pattern cross the surface of the Earth. These studies and observations are now being pursued by the STELab facility in Japan (Kojima and Kakinuma, 1990), and help provide ground-truth confirmation when compared with SMEI remote sensing observations, to locate and define heliospheric structures.…”

Section: Fflstory Of Smei Design and Developmentmentioning

confidence: 98%

The Solar Mass-Ejection Imager (SMEI) Mission

et al. 2004

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“…[3] Polar coronal holes start growing after solar maxima and attain their largest extension towards the heliographic equator during the declining phase of the solar cycle [Newkirk and Fisk, 1985;Kojima and Kakinuma, 1990;Rickett and Coles, 1991]. Simultaneously, large latitudinal gradients in SW speed arise close to the equator between the fast SW of coronal holes and the slow SW of the streamer belt extending around the minimum speed locus.…”

Section: Introductionmentioning

confidence: 99%

Latitudinal gradients of solar wind speed around the ecliptic: Systematic displacement of the streamer belt

Мурсула

Hiltula

Zieger

2002

Geophysical Research Letters

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[1] We study the effective latitudinal gradients of the solar wind (SW) speed in the two magnetic hemispheres around the heliographic equator by comparing observations at the Earth's orbit in Spring and Fall since 1964. We find that there is a large, statistically significant effective gradient of about 10 km/s/deg in the southern magnetic hemisphere around each solar minimum. However, no statistically significant effective gradient is found in the northern magnetic hemisphere. This difference implies a systematic displacement of the minimum speed locus of the streamer belt toward the northern magnetic hemisphere. We note that at least during one minimum the streamer belt and the heliospheric current sheet seem to have been oppositely displaced. We also show that the average SW speeds from the two magnetic hemispheres are roughly equal. Therefore, the earlier reported annual variation in SW speed at 1 AU is due to the displacement of the streamer belt and not due to different speeds from coronal holes of opposite polarity. The displacement of the streamer belt implies a new, persistent north-south asymmetry related to the solar magnetic cycle which needs to be explained by realistic solar dynamo models.

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Solar cycle dependence of global distribution of solar wind speed

Cited by 162 publications

References 31 publications

Geomagnetic activity and wind velocity during the Maunder minimum

Geomagnetic activity and wind velocity during the Maunder minimum

The Solar Mass-Ejection Imager (SMEI) Mission

Latitudinal gradients of solar wind speed around the ecliptic: Systematic displacement of the streamer belt

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