Numerical modeling of the equatorial electrojet UT-variation on the basis of the model GSM TIP

[摘要] In the presented work the results of numerical modeling of the UT-variationof the equatorial electrojet, executed on the basis of the model GSM TIP arepresented, taking into account the dynamo electric fields generated bythermospheric winds in a current-carrying layer of the ionosphere at heights80–175 km above a surface of the Earth. To the Global Self-consistentModel of the Thermosphere, Ionosphere and Protonosphere (GSM TIP), developedin WD IZMIRAN, a new block for the calculation of electric fields in theionosphere has been added. In this block the solution of thethree-dimensional equation describing the conservation law of the fullcurrent in the Earth's ionosphere is reduced to the solution of thetwo-dimensional equation by integration along geomagnetic field lines.Calculations of parameters of the near-Earth space plasmas have beenexecuted for quiet equinoctial conditions on 22 March 1987 during the minimumof solar activity.

It has been shown, that there is a distinct semidiurnal harmonic in thediurnal behavior of the linear density of the equatorial electrojet withmaxima at 23:00 UT and 15:00 UT, as well as with minima at 06:00 UT and 20:00 UT. Thegreatest and smallest values of the peak intensity of the equatorialelectrojet with respect to the diurnal behavior can differ by a factor oftwo. The longitudinal extent of the area of the equatorial electrojet doeshardly show any UT-variation, but the greatest longitudinal extent is at 06UT. With the growth of the peak intensity of the equatorial electrojet itslatitudinal extent also increases (on ~5–10°) a little. At thesame time the equatorial electrojet in the maxima of intensity hasapproximately an identical width, whereas in the minima the electrojet isnarrow in the morning and wide in the afternoon.

As for the surface density of the equatorial electrojet, its UT-variation ismuch weaker and equals ~1–3 A/km² and the peak intensity is equal~15–20 A/km². The latitudinal extent of the surface density ofthe equatorial electrojet is maximal at 23:00 UT and 15:00 UT and minimal at 06:00 UTand 20:00 UT.

[学科分类] 电子、光学、磁材料