Characteristics of the Equatorial Electrojet determined from an array of magnetometers in N-NE Brazil

Rigoti, Augustinho; Chamalaun, F. H.; Trivedi, N. B.; Padilha, Antônio L.

doi:10.1186/bf03352216

Cited by 36 publications

(38 citation statements)

References 40 publications

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“…Figure 3 is drawn after Fig. 5 of Rigoti et al (1999). The diagram also shows the EEJ and Sq variations as obtained by Rigoti et al (1999) from the modeling based on all available data for the longitude zone.…”

Section: Direction Of H East Of Geographic Northmentioning

confidence: 99%

“…The average induced effect as measured from the ratio of internal to external component ( H i/ H e) for Sq variations was found to be 0.38. Rigoti et al (1999) estimated that the internal part of H observed in Eastern Brazil region was less than 10% of the external component. These differences may be due to the presence of large conducting region in eastern part of Ethiopia.…”

Section: Effect Of Induced Current Due To Eejmentioning

confidence: 99%

“…The densest array of vector magnetometers was operated in N-NE Brazil from November 1990 to March 1991 (Rigoti et al, 1999). The location of the field stations are indicated in the map shown in Fig.…”

Section: Background Of the Present Studymentioning

confidence: 99%

“…Rigoti et al (1999) have described the analysis of H and Z data on 16 selected quiet days. They were aware of the very large geomagnetic declination in the region = 20 • W but no analysis of the declination (D) or eastward magnetic field component (Y ) data has been described so far.…”

Section: Equatorial Electrojet Modeling Brazilian Regionmentioning

confidence: 99%

“…3. Latitudinal variations of the four hourly (10-13) mean daily range M4 of H due to planetary and electrojet currents for 6 January 1991 (after Rigoti et al, 1999). total horizontal field H with respect to the geographic meridian was calculated according to the equation;…”

Section: Two Sheets Of Currents In the E-region Above The Dip Equatormentioning

confidence: 99%

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Asymmetries in the equatorial electrojet around N-E Brazil sector

Rastogi

Trivedi²

2009

Ann. Geophys.

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Abstract. The paper examines the data of geographic northward (X), eastward (Y) and vertical (Z) components of the magnetic field from a dense array of 26 vector magnetometers operated in N-NE Brazil from November 1990 to March 1991. As expected, the daily variation of X showed a minor maximum around 03:00-04:00 LT and a major maximum around 12:00 LT. The daily range of Y showed a strong minimum around noon at all stations. The combined Y and X indicated the direction of the equatorial electrojet currents to be flowing along 25 • north of east at the centre and 20 • north of east at the edges of the equatorial electrojet (EEJ) belt. The centre of the EEJ as defined by the zero intercept of the Z versus latitude was found to be near 1.0 • S dip latitude. The electrojet current was stronger in the northern half than in the southern half of the electrojet belt. These anomalies are suggested to be due to the abnormal distribution of the mean magnetic field in this region.

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Section: Direction Of H East Of Geographic Northmentioning

confidence: 99%

Section: Effect Of Induced Current Due To Eejmentioning

confidence: 99%

Section: Background Of the Present Studymentioning

confidence: 99%

Section: Equatorial Electrojet Modeling Brazilian Regionmentioning

confidence: 99%

Section: Two Sheets Of Currents In the E-region Above The Dip Equatormentioning

confidence: 99%

See 3 more Smart Citations

Asymmetries in the equatorial electrojet around N-E Brazil sector

Rastogi

Trivedi²

2009

Ann. Geophys.

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Imaging three‐dimensional crustal conductivity structures reflecting continental flood basalt effects hidden beneath thick intracratonic sedimentary basin

et al. 2015

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A large-scale array of long-period magnetic data and a deep-probing magnetotelluric profile were recorded in the intracratonic Paraná sedimentary basin in central eastern South America, which presents a thick and extensive sedimentary-magmatic sequence that allows its basement to be investigated only by indirect methods. Integration of the results from both methods showed that the crust beneath the basin presents several quasi-linear highly conductive channeled zones with limited lateral extent, in coincidence with some of the main tectonic structures recognized at the surface, and a moderate but pervasive lithosphere conductivity enhancement beneath its central part. Upward movement of CO 2 -bearing volatiles and magmas precipitating highly conducting mineral phases along discrete subvertical fault zones that served as feeder conduits for Early Cretaceous voluminous continental flood basalts was a likely process responsible for the localized conductivity enhancements. Correlation between some of the linear conductive zones and elongated magnetic anomalies and between the maximum depth occurrence of most of these conductive anomalies and the Curie depth at which crustal rocks lose their magnetism gives strong support to interconnected iron oxides (especially magnetite) and iron sulfides (such as pyrrhotite) as the main conductive sources. The moderate bulk conductivity increase in the crust and upper mantle beneath the central part of the basin is unexpected for a postulated cratonic basement and is tentatively associated with impregnation of the lithosphere by conducting minerals related either to widespread tectonic events in the Ordovician or Late Precambrian or to dispersed magmatic residues of an Early Cretaceous magma differentiation contaminating the entire lithosphere.

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Longitude‐dependent lunar tidal modulation of the equatorial electrojet during stratospheric sudden warmings

2017

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The effects of coupling between different layers of the atmosphere during Stratospheric Sudden Warming (SSW) events have been studied quite extensively in the past few years, and in this context large lunitidal enhancements in the equatorial ionosphere have also been widely discussed. In this study we report about the longitudinal variabilities in lunitidal enhancement in the equatorial electrojet (EEJ) during SSWs through ground and space observations in the Peruvian and Indian sectors. We observe that the amplification of lunitidal oscillations in EEJ is significantly larger over the Peruvian sector in comparison to the Indian sector. We further compare the lunitidal oscillations in both the sectors during the 2005–2006 and 2008–2009 major SSW events and during a non‐SSW winter of 2006–2007. It is found that the lunitidal amplitude in EEJ over the Peruvian sector showed similar enhancements during both the major SSWs, but the enhancements were notably different in the Indian sector. Independent from SSW events, we have also performed a climatological analysis of the lunar modulation of the EEJ during December solstice over both the sectors by using 10 years of CHAMP magnetic measurements and found larger lunitidal amplitudes over the Peruvian sector confirming the results from ground magnetometer observations. We have also analyzed the semidiurnal lunar tidal amplitude in neutral temperature measurements from Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) at 110 km and found lesser longitudinal variability than the lunitidal amplitude in EEJ. Our results suggest that the longitudinal variabilities in lunitidal modulation of the EEJ during SSWs could be related to electrodynamics in the E region dynamo.

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Characteristics of the Equatorial Electrojet determined from an array of magnetometers in N-NE Brazil

Cited by 36 publications

References 40 publications

Asymmetries in the equatorial electrojet around N-E Brazil sector

Asymmetries in the equatorial electrojet around N-E Brazil sector

Imaging three‐dimensional crustal conductivity structures reflecting continental flood basalt effects hidden beneath thick intracratonic sedimentary basin

Longitude‐dependent lunar tidal modulation of the equatorial electrojet during stratospheric sudden warmings

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