Electric fields in the equatorial ionosphere derived from CHAMP satellite magnetic field measurements

Alken, Patrick; Maus, Stefan

doi:10.1016/j.jastp.2009.02.006

Cited by 31 publications

(50 citation statements)

References 27 publications

(36 reference statements)

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“…DE3 "wave-4" structure has been found in many ionospheric data sets, including the EEF, equatorial electrojet current, and vertical ion drift velocities England et al, 2006;Alken and Maus, 2007;Lühr et al, 2008;Fejer et al, 2008;Alken and Maus, 2010b]. The wave-4 structure typically contains maxima over both Africa and South America.…”

Section: Discussionmentioning

confidence: 99%

“…The coefficients of this equation differ from the previous work of Alken and Maus [2010b] by a constant factor in order to improve numerical stability at the lower boundary where the conductivity nearly vanishes.…”

Section: Modeling the Equatorial Electrojet Currentmentioning

confidence: 95%

“…In section 3 we discuss the magnetometer stations and their data processing used in this study. In section 4 we discuss our modeling framework including several significant improvements over the previous work of Alken and Maus [2010b]. In section 5 we validate our electric field estimates against observations from the Communication/Navigation Outage Forecasting System (C/NOFS) satellite mission.…”

Section: Deriving a Time Series Of Eej Current Profiles From Ground Mmentioning

confidence: 99%

“…[4] Alken and Maus [2010b] developed a method to derive EEF estimates (and hence the ion drift velocities) at all longitudes, by modeling the EEJ current system using empirical inputs for the conductivities and wind field, and constraining the resulting current with magnetometer measurements from the CHAMP satellite to estimate the EEF. This method has the advantage of implicitly including longitudinal differences directly in the model, but does require satellite measurements to constrain the model.…”

Section: Introductionmentioning

confidence: 99%

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Longitudinal and seasonal structure of the ionospheric equatorial electric field

Alken¹,

Chulliat

Maus³

2013

JGR Space Physics

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[1] The daytime eastward equatorial electric field (EEF) in the ionospheric E-region plays an important role in equatorial ionospheric dynamics. It is responsible for driving the equatorial electrojet (EEJ) current system, equatorial vertical ion drifts, and the equatorial ionization anomaly. Due to its importance, there is much interest in accurately measuring and modeling the EEF. In this work we propose a method of estimating the EEF using CHAMP satellite-derived latitudinal current profiles of the daytime EEJ along with Δ H measurements from ground magnetometer stations. Magnetometer station pairs in both Africa and South America were used for this study to produce time series of electrojet current profiles. These current profiles were then inverted for estimates of the EEF by solving the governing electrostatic equations. We compare our results with the Ion Velocity Meter (IVM) instrument on board the Communication/Navigation Outage Forecasting System satellite. We find high correlations of about 80% with the IVM data; however, we also find a constant offset of about 0.3 mV/m between the two data sets in Africa. Further investigation is needed to determine its cause. We compare the EEF structure in Africa and South America and find differences which can be attributed to the effect of atmospheric nonmigrating tides. This technique can be extended to any pair of ground magnetometer stations which can capture the day-to-day strength of the EEJ.Citation: Alken, P., A. Chulliat, and S. Maus (2013), Longitudinal and seasonal structure of the ionospheric equatorial electric field,

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Section: Discussionmentioning

confidence: 99%

Section: Modeling the Equatorial Electrojet Currentmentioning

confidence: 95%

Section: Deriving a Time Series Of Eej Current Profiles From Ground Mmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Longitudinal and seasonal structure of the ionospheric equatorial electric field

Alken¹,

Chulliat

Maus³

2013

JGR Space Physics

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“…To compare the CHAMP and JULIA data, however, correction of n en by a factor of 4 was needed, just as found by Gagnepain et al [1977]. Details of the procedure to obtain electric field estimates with CHAMP data are described by Alken and Maus [2010a]. Anderson et al [2002] use a similar method to determine the electric field using ground magnetometers.…”

Section: Introductionmentioning

confidence: 99%

Reconciliation of rocket‐based magnetic field measurements in the equatorial electrojet with classical collision theory

2012

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[1] We provide an explanation for a long-standing (more than 35 years) discrepancy between theory and rocket experiments concerning the peak height of the electrojet current and the magnitude of magnetic field perturbation. The arbitrary correction of the electron-neutral collision frequency by a factor of 4, which has been used to explain these problems, is not necessary if the field line-integrated conductivities are used. Recent research using ground-based magnetometers and CHAMP have also used this constant connection to classical collision theory. These methods arbitrarily change the electron-neutral collision frequency. A field line-integrated theoretical study of the electrojet by G. Haerendel and J. V. Eccles, implemented in this paper, explains the height of the electrojet using classical collision frequency. Furthermore, we argue that since the correction factor is independent of the driving electric field, it is unlikely that anomalous electron collision frequency due to a nonlinear plasma instability (gradient drift) is involved.Citation: Kelley, M. C., R. R. Ilma, and V. Eccles (2012), Reconciliation of rocket-based magnetic field measurements in the equatorial electrojet with classical collision theory,

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An update to the Horizontal Wind Model (HWM): The quiet time thermosphere

Drob

Emmert

Meriwether

et al. 2015

Earth and Space Science

560

549

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The Horizontal Wind Model (HWM) has been updated in the thermosphere with new observations and formulation changes. These new data are ground-based 630 nm Fabry-Perot Interferometer (FPI) measurements in the equatorial and polar regions, as well as cross-track winds from the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite. The GOCE wind observations provide valuable wind data in the twilight regions. The ground-based FPI measurements fill latitudinal data gaps in the prior observational database. Construction of this reference model also provides the opportunity to compare these new measurements. The resulting update (HWM14) provides an improved time-dependent, observationally based, global empirical specification of the upper atmospheric general circulation patterns and migrating tides. In basic agreement with existing accepted theoretical knowledge of the thermosphere general circulation, additional calculations indicate that the empirical wind specifications are self-consistent with climatological ionosphere plasma distribution and electric field patterns.

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Electric fields in the equatorial ionosphere derived from CHAMP satellite magnetic field measurements

Cited by 31 publications

References 27 publications

Longitudinal and seasonal structure of the ionospheric equatorial electric field

Longitudinal and seasonal structure of the ionospheric equatorial electric field

Reconciliation of rocket‐based magnetic field measurements in the equatorial electrojet with classical collision theory

An update to the Horizontal Wind Model (HWM): The quiet time thermosphere

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