On the daytoday variation of the equatorial electrojet. Resulting from this current is an electrostatic field directed ew dawndusk in the equatorial day side of the ionosphere. Evidence of short spatial variability of the equatorial. Jul 26, 2006 the equatorial electrojet eej is a unique feature of the earths external current systems because it must flow along the dip equator. External and internal sources of variations in geomagnetic field in northern parts of south america. H which is the deviation of the horizontal component h of the geomagnetic field from its steady nighttime level. The partial reflection pr drifts at 98 km measured by the medium frequency mf radar operating at tirunelveli, india, situated close to the magnetic equator, are shown to have the combined effects of mesospheric winds and the equatorial electrojet. The field of the equatorial electrojet from champ data.
There is a controversy over whether the equatorial electrojet is a separate system with its own return currents at low latitudes or it is an integral part of the sq current system driven by emfs mostly beyond the sq focus. In certain relevant sections, the book discusses both the equatorial electrojet and the worldwide parts of the. Ionospheric eregion irregularities du1ing equatorial. Veenadhari1 1indian institute of geomagnetism, new panvel w, navi mumbai, india. The evidences for this behavior of the pr drifts are brought out from a detailed examination of the temporal variation of the dynamical and the. An objective technique has been adopted for the identification of the eej from the satellite data and estimation of the standard parameters associated with it. Equatorial electrojet crc press book onwumwchili is an internationally known and highly respected expert in the equatorial electrojet field a brand of geomagnetism. Conductivity, electric field and electron drift velocity. Global characteristics of the lunar tidal modulation of the. At the magnetic dip equator, where the magnetic field is exactly horizontal, this electric field has an interesting effect. Influence of equatorial electro jet on geomagnetic field. Introduction the partially ionized region of the upper atmosphere called the earths ionoshow to cite this paper.
Pdf the field of the equatorial electrojet from champ data. During the counter electrojet the type2 echoes were shown to disappear. The characteristics of longitudinal variability of equatorial electrojet eej and counter electrojet cej, presented in this study, are based on concurrent observations from a hitherto unsampled region of the world to examine the 1 degree of correlation between hourly means and monthly averaged hourly means of ground observations with equatorial electrojet climatological model eejm2. Long wavelength irregularities in the equatorial electrojet. First we show that for certain regions a comparison between scalar geomagnetic measurements that use different models to. Champ satellite magnetic field measurements are ideal for investigating the equatorial electrojet. The equatorial electrojet eej is a unique feature of the earths external current systems because it must flow along the dip equator.
In the african longitude sector, france started a collaboration with co. In the dayside ionosphere, the neutral winds set up a polarization electric field which usually points into the eastward direction. Equatorial electrojet and regular daily variation sri 3 j 1 d s5 and fi6 were shifted see table l, the computa tion of averages d or e is made after reducing the monthly values observed at 8, or 8, to the latitude of miltou or kotongoro by an interpola tion. Daytoday variability of h component of geomagnetic field in.
During a very strong daytime counter electrojet event on 21 january 1977. The worldwide solardriven wind results in the socalled sq solar quiet current system in the e region of the earths ionosphere 100 km altitude. Crosssectional profile determination of equatorial electrojet for various longitudes along dip equator using set of gauss coefficients for earths magnetic. Gpstec variation during low to high solar activity period. Observations by radar, rockets, satellites, and geomagnetic observatories are used to study eej. The complete spectrum of the equatorial electrojet related to solar tides.
Pdf geomagnetic stormtime variations often occur coherently at high latitude and the dayside dip equator where they affect the normal. The dip equator in comparison with other equators was considered. This is indicated on a magnetogram as an enhancement of the solar daily variation of the horizontal component of the magnetic field h and solar quiet day variation. The equatorial electrojet and the profile parameters b0 and. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. Pdf the field of the equatorial electrojet from champ. Equatorial electrojet and regular daily variation sr. Ionospheric eregion irregularities du1ing equatorial counter. Abstract the crosssectional profile of the equatorial electrojet is deter mined for various longitudes dong the dip equator, uehg a set of 48. This file contains additional information such as exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it.
Variation of the lunar tide in the equatorial electrojet. A concentration of electric current in the atmosphere found in the magnetic equator explanation of equatorial electrojet. Equatorial electrojet and regular daily variation srii. A detailed study of equatorial electrojet phenomenon using. Current densities become larger when the peaks move closer to the magnetic equator. Strength of the equatorial electro jet and geomagnetic. An expository study on the equatorial electrojet agha s. Equatorial electrojet article about equatorial electrojet. Daytoday variability of h component of geomagnetic field. Kobea et al equatorial electrojet as part of the global circuit. Equatorial electrojet year ieey, several countries started measurement campaigns in various equatorial areas africa, south america, india, vietnam. Equatorial electrojet model eejm2 the equatorial electrojet eej is an intense electric current flowing along the magnetic equator in the eregion of the ionosphere. Pdf equatorial electrojet as part of the global circuit. Some of the spatial features of the noontime eej are as follows.
The equatorial electrojet is a narrow belt of intense electric current in the ionosphere confined to about 30 around the dip equator. Estimates all eej tidal components for each month of a year, for seasons and all data during the years 2005 2010. The proper interpretation of these singlestation observations was quite demanding because all largescale variations, including the diurnal variation, are superimposed on the eej signal of interest. The electrojet current produces a large enhancement of the surface component of the geomagnetic field at and in the vicinity of the dip equator. A manifestation of the equatorial electrojet is a large sq variation in the horizontal or magnetic northward. The daytoday variability of the equatorial electrojet in peru. A study of the equatorial electrojet in situ measurements of magnetic and electric fields. Ionospheric eregion irregularities du1ing equatorial counter electrojet r g rastogi dcpartmclll of physics, gujarat university, ahmecabad 380 009. In principle, measuring this perturbation in equatorial magnetometers could provide a direct measure of the eej. The equatorial electrojet eej is an eastward electric current on the dayside. The equatorial electrojet eej is a narrow ribbon of current flowing eastward in the day time equatorial region of the earths ionosphere. Recent magnetic observations from the champ, orsted, and sacc satellites, comprising more than 95,000 dip equator crossings from 1999 to 2006, have provided an unprece. Conductivity, electric field and electron drift velocity within the equatorial electrojet by r. This current is unique by virtue of its restricted location, magnitude and.
Plain language summary based on 5 years of magnetic. Complete solar tidal spectra of the equatorial electrojet. The relative locations of the internal and external sources are indicated in the map of figure 1. The electrojet current peaks right at the dip equator. They concluded that it is the lunar semidiurnal tide that is amplified by ssw and modulates the lowlatitude and midlatitude ionosphere. To construct a useful model of the equatorial electrojet, we investigate the mean value of the electrojet current, and its deviation from the mean.
Equatorial eleotrojet and regular daily variation ssi 21 1. The complete spectrum of the equatorial electrojet related. Equatorial electrojet as a diagnostic tool of geomagnetic. By deviation, we refer to the actualdaytodayvariabilityofthecurrentstrengthaboutits climatological mean. Variability of hcomponent of the geomagnetic field from.
Data, innovation, and science cluster swarm equatorial. Longitudinal variation of the lunar tide in the equatorial. Request pdf the equatorial electrojet and the profile parameters b0 and b1 around midday this study presents the results of the comparison of b0, b1 and hmf2 with. The resulting upward e x b drift of the electrons generates. The equatorial associated with upgoing and downgoing waves, electrojet plasma irregularities are discussed in often show periodic variations. At the lower portion of the ionosphere, known as the eregion 90120 km altitude, near the equator these currents can be enhanced even further by the horizontal geometry of the geomagnetic main. The field of the equatorial electrojet from champ data article pdf available in annales geophysicae 242. There is a controversy over whether the equatorial electrojet is a separate system with its own return currents at low latitudes or it is an integral part of the sq. Introduction according to chapman 1, the equatorial electrojet is defined as a high concentration of electric current flowing from west to east in a narrow belt flanking the dip equator on the sunward hemisphere. Effect of sudden stratospheric warming on lunar tidal.
Spatiotemporal characterization of the equatorial electrojet. The equatorial electrojet eej is a narrow ribbon of current flowing eastward in the day time. Characteristics of the equatorial electrojet determined from. Equatorial electrojet as part of the global circuit. The equatorial electrojet eej is an intense electric current flowing along the magnetic equator in the eregion of the ionosphere. Variability of hcomponent of the geomagnetic field from some.
The power spectra are computed using the code of ferch and sudan, averaging over times as long as 20 seconds. This provides us with a tool to determine the nature of the variations imposed by competing main field models on the equatorial region. To study the electrojet, magnetically quiet days should be selected to ensure that the diurnal variation consists of the magnetic field variations due to the eej and. Our analysis of the equatorial electrojet variations obtained from the magnetic swarm data indicates that the stormtime penetration electric fields were, most likely, the main driver of the observed ionospheric effects at the initial phase of the storm and at the beginning of the main phase. Characteristics of the equatorial electrojet determined from an array. The typical quiet day variations of the equatorial electrojet eej current intensity with time of the day, season, sunspot number, and geomagnetic latitude are presented in terms of the corresponding variations of. Total electron content tec, equatorial ionization anomaly eia, solar cycle, equatorial electrojet eej strength 1. The equatorial electrojet eej is an intense electric current that flows in the ionosphere in a narrow zone above the magnetic dip equator during the daytime. There have also been some highlights on the eregion ionosphere.