Sq currents in the American equatorial zone during the IGY—I Seasonal effects

Hutton, Rosemary

doi:10.1016/0021-9169(67)90233-4

Cited by 47 publications

(9 citation statements)

References 20 publications

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“…In earlier works, Yacob [1975] pointed out that the dipequatorial enhancement of S q fields becomes minimum during local summer in the Indian sector. Also, a similar feature can be found in the S q and EEJ profiles in the south American region given by Hutton [1967]. Perhaps, the observed winter-summer asymmetry of EEJ is not peculiar feature of the east Asian region but is a general feature.…”

Section: Seasonal Variationssupporting

confidence: 73%

Reexamination of the S_q‐EEJ relationship based on extended magnetometer networks in the east Asian region

et al. 2010

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[1] We reexamined the daily S q -equatorial electrojet (EEJ) relationship based on these extended magnetometer networks in the east Asian region: (1) the Circum-pan Pacific Magnetometer Network (CPMN), (2) the International Real-time Magnetic Observatory Network (INTERMAGNET), and (3) the World Data Center for Geomagnetism, Kyoto (WDC). Daily variations of the geomagnetic field for geomagnetically quiet days (Kp ≤ 2+) from 1996 to 2005 were analyzed. Noontime eastward S q current intensities were estimated by latitudinally integrating the north-south component of the S q field. The corresponding EEJ intensities were estimated from the daily geomagnetic field variations observed at Davao station (dip latitude of −0.84°deg). We discovered that these intensities of daily S q and EEJ are well correlated on a long-term basis (r = 0.80). The dependences on the solar activity (as indicated by F10.7) and season (the day number) of S q and EEJ variations were examined. It was demonstrated that both daily S q and EEJ intensities are correlated to F10.7 with similar sensitivities. F10.7 is known to show similar variations with solar EUV radiation which causes ionization and heating of the ionosphere. For seasonal dependence, both daily S q and EEJ intensities show predominant semiannual variations with similar spring-fall asymmetry. The effect of seasonal changes of the EUV flux into the low-latitude ionosphere is considered. Our results indicate that the daily values of S q and EEJ react, in the same manner, to temporal changes of solar ionization and heating of the ionosphere.

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Section: Seasonal Variationssupporting

confidence: 73%

Reexamination of the S_q‐EEJ relationship based on extended magnetometer networks in the east Asian region

et al. 2010

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“…Features of the equatorial electrojet have been studied at different longitudes: e.g., for the Pacific region ∼ 160°W by Mason (1963); for the South American region ∼ 75°W by Forbush and Casaverde (1961), Hutton (1967); ∼ 62°W by Rastogi et al (2008); ∼ 45°W by Rigoti et al (1999), Rastogi et al (2010); for the African region ∼ 5°E by Onwumechili (1959), Ogbuehi and Onwumechilli (1963); ∼ 11 • E by Doumouya et al (1998); ∼ 16°E by Mayaud (1976a, 1976b); ∼ 39°E by Rastogi and Chandra (2015); for the Central Asian region ∼ 77°E by , Rabiu et al (2013); ∼ 81°E by Rastogi et al (2004); for the East Asian region ∼ 125°E by Yamazaki et al (2010). Comparisons of the equatorial electrojet intensities at various longitude sectors have revealed a strong dependence on the main field B (Rastogi 1962;Doumouya et al 2003;Abdul Hamid et al 2015).…”

Section: Eejmentioning

confidence: 99%

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

2016

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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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“…At the same time, models which reasonably explain the observed facts are searched, for example by OGBUEHI et al (1967) andSUGIURA andPoxos (1969). Contributions from many authors are well reviewed by ONWUMECHILLI (1967) andHUTTON (1967).…”

Section: Distributions Of the Return Currentsmentioning

confidence: 99%

Returning Flow of the Equatorial Electrojet Currents

Suzuki

1973

J. geomagn. geoelec

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A distribution of return currents of the equatorial electrojet was calculated by solving the partial differential equation, div Je-o, under the condition of non-uniform distribution of ionospheric conductivity and the boundary condition at the equator which was deduced from ground magnetic variations. It is found that the return currents decrease rather quickly with increasing distance from the equator. Comparing the distribution of the return currents with that of the Sq currents, it is concluded that the contributions of the return currents to the ground magnetic variations are mostly less than ten and rarely twenty per cent of those of the Sq currents, at any point except in small areas just under the current vortices.

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Sq currents in the American equatorial zone during the IGY—I Seasonal effects

Cited by 47 publications

References 20 publications

Reexamination of the S_q‐EEJ relationship based on extended magnetometer networks in the east Asian region

Reexamination of the S_q‐EEJ relationship based on extended magnetometer networks in the east Asian region

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

Returning Flow of the Equatorial Electrojet Currents

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Sq currents in the American equatorial zone during the IGY—I Seasonal effects

Cited by 47 publications

References 20 publications

Reexamination of the Sq‐EEJ relationship based on extended magnetometer networks in the east Asian region

Reexamination of the Sq‐EEJ relationship based on extended magnetometer networks in the east Asian region

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

Returning Flow of the Equatorial Electrojet Currents

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Reexamination of the S_q‐EEJ relationship based on extended magnetometer networks in the east Asian region

Reexamination of the S_q‐EEJ relationship based on extended magnetometer networks in the east Asian region