Variations of the Auroral Electrojet Belt During Substorms

Xu, Weihua

doi:10.1002/cjg2.1350

Cited by 5 publications

(4 citation statements)

References 21 publications

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“…The different behavior of AU and AL during major geomagnetic storms is probably due to the current systems responsible for AU and AL . Xu [] has shown that the eastward current system responsible for AU moves equatorward with increasing activity, but the westward current system responsible for AL does not. This means that, for increasing activity, the current responsible for AU may move equatorward of the AE magnetometers.…”

Section: Resultsmentioning

confidence: 99%

Prediction of the AU, AL, and AE indices using solar wind parameters

Temerin

Liu

2013

JGR Space Physics

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[1] An empirical model that predicts the AU index, a measure of the Earth's east electrojet, derived from magnetometers in the Northern Hemisphere, is introduced together with an improved AL model which, combined with the AU model, produces an AE model. All models are based on solar wind and interplanetary magnetic field parameters and the solar F 10.7 index for the years 1995 to 2001. The linear correlation coefficient (LC) between the 10 min averaged AU index and the model is 0.846 for the years 1995-2001. The LC for the updated AL model is 0.846, and using AE = AU -AL, the LC for the AE model is 0.888. The better LC of the AE model over AU and AL models is because AU and AL are better correlated than their errors. The models show that (1) solar ultraviolet intensity plays a significant role in auroral activity by changing the ionospheric conductivity and scale height. Increasing solar ultraviolet intensity increases the eastward electrojet as measured by AU but decreases the westward electrojet as measured by AL; (2) solar wind dynamic pressure also affects the auroral electrojet indices, although they are much more strongly dependent on the solar wind velocity and the interplanetary magnetic field; (3) AU and AL behave differently during geomagnetic storm main phases: AU, unlike AL, can drop to a small value during storms; (4) the longer averaged auroral electrojets indices can be predicted well but shorter timescale variations are less predictable.

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Section: Resultsmentioning

confidence: 99%

Prediction of the AU, AL, and AE indices using solar wind parameters

Temerin

Liu

2013

JGR Space Physics

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“…RAURIC builds a solid basis for simulating the image of ionospheric LBH dayglow emissions and the data inversion technique. We will study the response of the LBH dayglow emissions to the ionosperic space weather (Ma et al, 2002;Xu, 2009) and develop the dayglow removal technique (Strickland et al, 1994;Gladstone, 1994) in the future work.…”

Section: Resultsmentioning

confidence: 99%

A Method to Calculate the Ionospheric LBH Dayglow Emissions for Large Field of View

Yong-Chao

Zhang

et al. 2014

Chinese J of Geophysics

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LBH dayglow emissions in the ionosphere, produced by the photoelectrons impact on the nitrogen molecules, are the most prominent molecular signals in the far ultraviolet range. Imaging the LBH dayglow emissions from the space can be a powerful method to monitor the state of the upper atmosphere. According to direct excitation theory and spherical geometry, the spectral characteristics of the LBH emission are analyzed and a revised method (RAURIC) to calculate the column emission rate of the LBH dayglow emissions for large field of view is given. Two main limitations of AURIC, that are the definition of the observation azimuth angle and the treating of the solar zenith angle as a constant along a line of sight, are improved in RAURIC. The column emission rates of the LBH bands in the range of 140∼180 nm are calculated with the method. Comparisons with results from AURIC show great agreement in nadir, while RAURIC should be used in other lines of light, especially for large field of view. This work provides a solid basis for simulating the image of ionospheric LBH dayglow emissions and the data inversion technique.

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“…First, we derived the standard deviation (SD) of each observatory from the data within Similar to the AE index, we took a stack plot of the X components at high-latitudes; chose the envelope curve as a proxy of electrojets. Since there are two components of westward electrojet, the morning westward electrojet is related to the two-cell convection pattern, while the midnight westward electrojet is closed by the substorm current wedge [7,23]. The different sections of the westward electrojet correspond to different dynamic processes, so we plot the envelope curve for each sector.…”

Section: Data Selection and Analysismentioning

confidence: 99%

Nightside field-aligned current during the April 6, 2000 superstorm

et al. 2010

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Using the east-west geomagnetic disturbance fields observed from stations at mid-latitudes, we investigate the characteristics of field-aligned currents on the nightside during the April 6, 2000 superstorm. The results indicate that there is an eastward disturbance on the nightside of Northern Hemisphere during the main phase of magnetic storm, while the interplanetary magnetic field (IMF) is continued southward. The positive disturbances in the postmidnight are larger than that in the premidnight. This suggests that upward field-aligned currents develop on the nightside, when the IMF is directed southward. The peak of upward fieldaligned currents is located in postmidnight, and it will be more obvious at substorm expansion. We get the conclusion that both partial ring current and region-2 field-aligned current shift to dusk sector. The upward region-2 current is decreased at substorm onset, and intensified after it. We also investigate the relationship between the upward field-aligned currents on the nightside and the auroral electrojets at high latitudes. It shows a good correspondence between region-2 current and the westward electrojet in the postmidnight. We suppose that they are both associated with the convection electric field. main phase, field-aligned current, auroral electrojet, substorm current wedge Citation: Wang Y, Hong M H, Chen G X, et al. Nightside field-aligned current during the April 6, 2000 superstorm.As one of most important parts of the solar wind-magnetosphere-ionosphere coupling system, field-aligned currents connect the currents flowing in the magnetosphere and ionosphere. The large-scale FACs exhibit the traditional region 1/region 2 current pattern and the dayside region 0 (traditional cusp) current systems. When solar wind disturbances travel to the Earth magnetopause, the generation of dayside field-aligned currents will lead to magnetic impulse events at high-latitude ionosphere [1][2][3], and also disturb the mid-latitude magnetic field [4]. The Region 1 FieldAligned Currents (R1FACs) flow into high latitude ionosphere on the dawnside and out of ionosphere on the duskside. The Region 2 Field-Aligned Currents (R2FACs) are distributed in the lower latitude, which flow in the opposite direction. The closure of R1FACs in the magnetosphere is located in the plasma sheet and the magnetospheric boundary layer, while R2FACs are closed in the inner magnetosphere by the Partial Ring Current (PRC) [5]. The R2FACs are intensified during magnetic storms accompanied with the development of Ring Current (RCs) and PRCs [6]. At substorm onset, the cross-tail current is collapsed and the current wedge formed in night side with westward eletrojet closed around midnight in the ionosphere [7]. The energy stored in the magnetotail enters high-latitude ionosphere through field-aligned currents and the disturbances in the ionosphere will map to magnetosphere. Since the fieldaligned currents are related to many processes in ionosphere-magnetosphere coupling, such as particle precipitation, electric field ...

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Variations of the Auroral Electrojet Belt During Substorms

Cited by 5 publications

References 21 publications

Prediction of the AU, AL, and AE indices using solar wind parameters

Prediction of the AU, AL, and AE indices using solar wind parameters

A Method to Calculate the Ionospheric LBH Dayglow Emissions for Large Field of View

Nightside field-aligned current during the April 6, 2000 superstorm

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