Rocket measurement of<i>Sq</i>ionospheric currents over Kagoshima, Japan

Yabuzaki, T.; Ogawa, Teiichiro

doi:10.1029/ja079i013p01999

Cited by 9 publications

(5 citation statements)

References 13 publications

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“…The results revealed that horizontal current intensity is on the order of 10 A/km (not shown here). Taking account that the current intensity in our analysis is height‐integrated through the dynamo region of the ionosphere of thickness of about 10 km, the current density is estimated to be on the order of A/km 2 , which is in agreement with the current density detected by rocket measurements [e.g., Yabuzaki and Ogawa , 1974; Pfaff et al , 1997].…”

Section: Spherical Harmonic Analysis Of the S And L Fieldssupporting

confidence: 82%

An empirical model of the quiet daily geomagnetic field variation

et al. 2011

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[1] An empirical model of the quiet daily geomagnetic field variation has been constructed based on geomagnetic data obtained from 21 stations along the 210 Magnetic Meridian of the Circum-pan Pacific Magnetometer Network (CPMN) from 1996 to 2007. Using the least squares fitting method for geomagnetically quiet days (Kp ≤ 2+), the quiet daily geomagnetic field variation at each station was described as a function of solar activity SA, day of year DOY, lunar age LA, and local time LT. After interpolation in latitude, the model can describe solar-activity dependence and seasonal dependence of solar quiet daily variations (S) and lunar quiet daily variations (L). We performed a spherical harmonic analysis (SHA) on these S and L variations to examine average characteristics of the equivalent external current systems. We found three particularly noteworthy results. First, the total current intensity of the S current system is largely controlled by solar activity while its focus position is not significantly affected by solar activity. Second, we found that seasonal variations of the S current intensity exhibit northsouth asymmetry; the current intensity of the northern vortex shows a prominent annual variation while the southern vortex shows a clear semi-annual variation as well as annual variation. Thirdly, we found that the total intensity of the L current system changes depending on solar activity and season; seasonal variations of the L current intensity show an enhancement during the December solstice, independent of the level of solar activity.

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Section: Spherical Harmonic Analysis Of the S And L Fieldssupporting

confidence: 82%

An empirical model of the quiet daily geomagnetic field variation

et al. 2011

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“…The rocket flight of Yabuzaki & Ogawa (1974) at Kagoshima Space Centre in Japan supplied the RFR 60.…”

Section: Rocket Flight Results Between the Dip Equatorial Zone And Thmentioning

confidence: 99%

“…Burrows & Stolarik 1967); RFR 34 and 35 also from the Pacific off Peru (Maynard 1967); and RFR 60 from Kagoshima Space Centre near Kanoya Observatory in Japan (Yabuzaki & Ogawa 1974); for Group 5: RFR 01 at White Sands in New Mexico (Maple, Bowen & Singer 1950); RFR 17 at Holloman Missile Development Center in New Mexico (Hutchinson & Schuman 1961); RFR 25 and 26 from Woomera Rocket Range in south Australia (Burrows & Hall 1965); and RFR 27 to 30 from Wallops Island in Virginia about 180 km east of Fredricksburg observatory (Davis, Stolarik & Heppner 1965); for Group 6: RFR 05 from the Atlantic Ocean off Greenland (Cahill 1959); RFR 12 to 15 from Fort Churchill in Canada (Meredith et al 1961); and RFR 16 also from Fort Churchill (Conley 1960).…”

Section: Introductionmentioning

confidence: 99%

A study of rocket measurements of ionospheric currents-II. Ionospheric currents outside the dip equatorial zone

Onwumechili

1992

Geophysical Journal International

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SUMMARY This second part of the series has studied ionospheric currents outside the dip equatorial zone in the three groups of: high‐latitude currents beyond 70° latitude (Group 6), daytime currents within 35° to 70° dip latitude (Group 5), and daytime currents within 7° to 35° dip latitude (Group 4). Ionospheric currents have been found and measured with rockets in all three groups, and their directions are in conformity with expectations from geomagnetic variations: eastwards equatorward of the Sq focus (Group 4), westwards between the Sq focus and high latitudes (Group 5), and complex in the higher and polar latitudes (Group 6). Of great interest is the discovery that the currents occur in the two eastward layers in Group 4 but only in one layer in Groups 5 and 6. The altitude of peak current is 105 ± 8 km and 123 ± 8 km for the two layers of Group 4 respectively, 112 ± 3 km in Group 5 and about 120 km in Group 6. The peak current density is about 1.5 A km‐2 and 1 A km‐2 for layers 1 and 2 respectively in Group 4 and difficult to determine in Groups 5 and 6. The altitude extent of the current layers decreases towards the Sq focus. On average the altitude extent is 19 ± 7 km and 15 ± 8 km for layers 1 and 2 of Group 4 respectively, 17 ± 3 km in Group 5 and is difficult to determine in Group 6. The two peaks of current density in Group 4 did not appear to correlate with peaks of electron density measured with the same rocket. However, the upper current peak occurred near the peak of Pedersen conductivity.

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“…Later, he estimated the conductivity of the atmosphere that is required to explain Sq variations and attributed this conductivity to the ionization of the atmosphere caused by the solar radiation (Schuster 1908). The existence of the ionospheric currents was later confirmed experimentally by sounding rockets (e.g., Singer et al 1951;Cahill 1959;Davis et al 1967;Maynard 1967;Yabuzaki and Ogawa 1974;Pfaff et al 1997). It is now well established that electric currents of the order of several µA/m 2 flow on the dayside of the E-region ionosphere, in the altitude range of 90-150 km.…”

Section: Observational Overviewmentioning

confidence: 88%

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

Yamazaki¹,

Maute²

2017

Earth's Magnetic Field

153

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A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several µA/m 2 flowing on the sunlit side of the Eregion ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the nonspecialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

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Rocket measurement ofSqionospheric currents over Kagoshima, Japan

Cited by 9 publications

References 13 publications

An empirical model of the quiet daily geomagnetic field variation

An empirical model of the quiet daily geomagnetic field variation

A study of rocket measurements of ionospheric currents-II. Ionospheric currents outside the dip equatorial zone

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

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