Atmospheric solar tides and their electrodynamic effects—I. The global Sq current system

Forbes, Jeffrey M.; Lindzen, Richard S.

doi:10.1016/0021-9169(76)90073-8

Cited by 94 publications

(52 citation statements)

References 37 publications

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“…3 and 4) are approximately those of the predicted (1, 1) tide in the lower thermosphere (FORBES and LINDZEN, 1976). The agreement is better for the zonal component in each case, while the meridional component could be fitted to a wave with a larger vertical wavelength of about 40 km rather than the 24 km corresponding to the theoretical (1, 1) mode.…”

Section: The Diurnal Tidessupporting

confidence: 58%

“…First, the meridional phase is always advanced with respect to the theoretical (1, -2) mode (FORBES and LINDZEN, 1976) and, secondly, the zonal phase never becomes orthogonal to the meridional phase within the height range of the present data. In fact, near 120 to 130 km, the zonal phase actually leads the meridional phase significantly, and only slowly tends towards orthogonality (if at all) above the range of these data.…”

Section: Km and Abovementioning

confidence: 53%

“…The discussion will be limited to a comparison of the present results with the previous most comprehensive analyses of experimental data in this altitude range, that is with AMAYENC (1974), SALAH et al (1975), HINES (1965) and NEAL (1975), and with recent theoretical models of the thermospheric tides which are relevant to (1970,1971), HONG (1973) andFORBES andLINDZEN (1976). These authors also give detailed discussion of the relationship between previous experimental and theoretical studies, to which the reader is referred.…”

Section: Discussionmentioning

confidence: 87%

“…MAEDA (1955) and KATO (1956) and, more recently, STENING (1969, 1973, TARPLEY (1970), RICHMOND et al (1976) andFORBES andLINDZEN (1976) have attempted to reconcile a computed ionospheric dynamo, derived from various wind models, with the global structure of the Sq magnetic variation. LINDZEN , 1976) and LINDZEN and HONG (1974 have successfully developed the theory of the propagation of atmospheric tides from the strato-mesosphere into the lower thermosphere.…”

Section: Introductionmentioning

confidence: 99%

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Rocket measurements of annual mean prevailing, diurnal and semi-diurnal winds in the lower thermosphere at mid-latitudes.

Rees

1979

J. geomagn. geoelec

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Approximately four hundred neutral wind profiles of the lower thermosphere, obtained by rocket-borne techniques since 1957, have been analysed in terms of diurnal and latitudinal variability.Some 15 of these measurements have been carried out during daytime conditions, providing an insight into the dynamics of the daytime thermosphere.The dominant tidal modes (1, 1), (1, --2), (2, 2) and (2, 4) have each been identified in the statistical analysis, and their amplitudes and phases determined as a function of altitude within the lower thermosphere. Agreement is found between the characteristics of the data and recent models of the tides in the lower thermosphere. The (1, -2) mode, for example, appears more strongly in the meridional than zonal components; however, its phase appears to be 3 to 4 hr advanced compared with model calculations. This mode may be strongly enhanced after even moderate geomagnetic activity, indicating that the high latitude energy source responsible for the enhancement may also cause the phase advancement relative to models of the (1, -2) tide as generated only by in situ solar BUY heating.

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Section: The Diurnal Tidessupporting

confidence: 58%

Section: Km and Abovementioning

confidence: 53%

Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rocket measurements of annual mean prevailing, diurnal and semi-diurnal winds in the lower thermosphere at mid-latitudes.

Rees

1979

J. geomagn. geoelec

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“…Early simulations of the ionospheric dynamo (Stening 1969;Tarpley 1970;Richmond et al 1976;Forbes and Lindzen 1976a) demonstrated that the negative-mode diurnal tide can generate a global electric current system similar to those derived from Sq variations. Thus, the negative-mode diurnal tide was considered to be the primary driver of the Sq currents.…”

Section: Geomagnetic Daily Variations and Atmospheric Tidesmentioning

confidence: 97%

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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Mechanisms underlying the prereversal enhancement of the vertical plasma drift in the low‐latitude ionosphere

2015

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The evening prereversal enhancement (PRE) of the vertical plasma drift has important consequences for the Appleton density anomaly and the stability of the nighttime ionosphere. Simplified simulations were used to review the three competing theories of the PRE origin, to explore their relative importance, and to indentify their interdependence. The mechanisms involved in the generation and climatology of the PRE are, first, a curl-free electric field response to rapid changes in the vertical electric field associated with the nighttime F region dynamo; second, a divergence of Hall currents in the E region away from the magnetic equator; and, third, the moderating effect of the large Cowling conductivities in the equatorial E region. The simulations indicate that the equatorial Cowling conductivity creates an important current path that limits the other two mechanisms prior to equatorial sunset and releases them after equatorial sunset. The curl-free mechanism is the dominant mechanism when the terminator and magnetic meridian are aligned in part due to the accelerating F region zonal wind. When the solar terminator is not aligned with the magnetic meridian, there is an interaction involving all three mechanisms contributing to the magnitude and timing of the PRE. Finally, the altitude profile of the PRE decays more quickly with altitude when the curl-free mechanism dominates as compared to when the Hall current mechanism dominates.

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Atmospheric solar tides and their electrodynamic effects—I. The global Sq current system

Cited by 94 publications

References 37 publications

Rocket measurements of annual mean prevailing, diurnal and semi-diurnal winds in the lower thermosphere at mid-latitudes.

Rocket measurements of annual mean prevailing, diurnal and semi-diurnal winds in the lower thermosphere at mid-latitudes.

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

Mechanisms underlying the prereversal enhancement of the vertical plasma drift in the low‐latitude ionosphere

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