Observations of the generation of eastward equatorial   electric fields near dawn

Kelley, M. C.; Rodrigues, F. S.; Pfaff, R. F.; Klenzing, J.

doi:10.5194/angeo-32-1169-2014

Cited by 19 publications

(40 citation statements)

References 27 publications

(45 reference statements)

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“…Kelley et al . [] proposed that the formation mechanism of the dawn enhancement has a resemblance to that of the PRE.…”

Section: Discussionmentioning

confidence: 99%

“…A question that will naturally be raised is what is responsible for the formation of the dawn enhancement? Kelley et al [2014] proposed that the formation mechanism of the dawn enhancement has a resemblance to that of the PRE.…”

Section: 1002/2015ja021972mentioning

confidence: 99%

“…They pointed out that the dawn enhancement occurs later at lower heights. Recently, Kelley et al [2014] also presented six events of enhancement using C/NOFS satellite measurements. Those cases show that the vertical plasma drift enhances near dawn during June solstice in the Pacific longitude sector.…”

Section: Introductionmentioning

confidence: 99%

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The dawn enhancement of the equatorial ionospheric vertical plasma drift

et al. 2015

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Previous studies have reported that a dawn enhancement does not present in the statistical picture of the equatorial ionospheric vertical plasma drift, while it clearly shows in case measurements. In this statistical study, it is the first time to investigate the occurrence of the dawn enhancement in the equatorial ionospheric vertical plasma drift from ROCSAT‐1 observations during geomagnetic quiet times. The dawn enhancements occur most frequently in June solstice and least frequently in December solstice. The statistical survey shows that the occurrence depends on the magnetic declination. The enhancement has the strongest amplitude in regions near 320° longitude and peaks during June solstice. The dawn enhancement reaches its peak after the sunrise in conjugated E regions. Furthermore, it is found that the dawn enhancement is closely related to the difference between the sunrise times in the conjugated E regions (sunrise time lag). The dawn enhancement occurs easily in regions with a large sunrise time lag.

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“…Kelley et al . [] proposed that the formation mechanism of the dawn enhancement has a resemblance to that of the PRE.…”

Section: Discussionmentioning

confidence: 99%

Section: 1002/2015ja021972mentioning

confidence: 99%

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The dawn enhancement of the equatorial ionospheric vertical plasma drift

et al. 2015

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“…as observed in vertical drifts, which is a regular phenomena observed by ground-and space-based instrument near sunset hours in the equatorial ionosphere (Kelley et al 2014). Further, the vertical drifts are accompanied by eastward drifts (Aggson et al 1995).…”

Section: Resultsmentioning

confidence: 71%

Analysis of local ionospheric variability based on SVD and MDS at low-latitude GNSS stations

Dabbakuti

Kanchumarthi

2016

Earth Planet Sp

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Investigation of ionospheric anomalies during equatorial and low latitude is of major concern for modeling and global navigation satellite system (GNSS) applications. Total electron content (TEC) varies with the ionospheric conditions, which will lead to the errors in the global positioning system (GPS) measurements. It is therefore a method that is necessary to characterize the ionospheric anomalies for satellite-based navigation systems. In this study, characterization of ionospheric variations based on the singular value decomposition (SVD) and classical multidimensional scaling (MDS) methods was studied. The yearly and daily variations are decomposed from the GPS-TEC, international reference ionosphere (IRI) 2007 and IRI 2012 models TEC over the three low-latitude GNSS stations located at Koneru Lakshmaiah University (KLU-Guntur), Hyderabad and Bangalore, respectively. From the results, it is found that there is a strong correlation between GPS-TEC and IRI models. The correlation coefficient for the first three singular values is more than 0.86. From this, it is possible to reconstruct more than 85 % of the variability contained in global GPSderived VTEC data (for year 2013) by using only the first three modes. The semiannual variation has maximum value during March-April and September-October and has minimum value during June-July. It is observed that the annual variations have maximum value in summer and minimum value in winter, and the amplitudes decrease with increasing latitude. Further, opposite latitudinal asymmetry among annual and semiannual variations for three GNSS stations is noticed. SVD and MDS methods clearly show time-varying characteristics and the absence of the winter anomaly at low-latitude GNSS stations.

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“…In these techniques, primarily the rate of change of the ionospheric height over the magnetic equator is measured, which is directly proportional to the variation in the strengths of equatorial electric field, as the winds do not contribute to the changes in the height of the ionospheric layers. Studies of global-scale variations of vertical drifts have been made using measurements from space-based instruments and payloads, such as the Ion Drift Meter (IDM) on-board the Atmospheric Explorer E (AE-E) satellite (Fejer et al, 1995;Scherliess & Fejer, 1999), Ionospheric Plasma and Electrodynamic Instrument (IPEI) payload on-board Republic of China Satellite-1 (ROCSAT-1; Kil et al, 2007;Fejer et al, 2008), and Ion Velocity Meter (IVM) and Coupled Ion Neutral Dynamics Investigation (CINDI) on-board the Communication/Navigation Outage Forecast System (C/NOFS) satellite (Kelley et al, 2014;Stoneback et al, 2011;Zhang et al, 2016). Incoherent Scatter Radar (ISR) at Jicamarca Radio Observatory, Peru yields the most accurate values of the vertical drifts, both during day and night times (Anderson et al, 2002(Anderson et al, , 2004Fejer, 1993;Woodman, 1970).…”

Section: Introductionmentioning

confidence: 99%

On Estimation of Daytime Equatorial Vertical (E × B) Plasma Drifts Using Optical Neutral Dayglow Emission Measurements

Karan

Pallamraju

2020

JGR Space Physics

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Vertical drift (E × B) over the geomagnetic equator of the Earth is one of the fundamental parameters that governs the equatorial electrodynamics, which is responsible for the formation of large-scale phenomena in low and equatorial latitudes. We present a novel approach using ground-based optical neutral oxygen dayglow emission intensity measurements to estimate the daytime equatorial vertical drifts. The diurnal patterns of the dayglow emission intensities at OI 557.7, 630.0, and 777.4 nm wavelengths obtained from a low-latitude location, Hyderabad (78.4°E, 17.5°N; 8.9°N MLAT), India, are observed to be symmetric with respect to local noon on some days and asymmetric on some other. The extent of asymmetric nature is characterized by a parameter called Asymmetricity in Time (AT), which shows similar variations with the integrated Equatorial Electrojet (EEJ) strength. AT values obtained from the dayglow measurements are used to infer the vertical drifts. Vertical drifts derived by this method match well with the global climatological model estimates and with radar measurements. This new approach provides an alternative method for obtaining vertical drifts to enable systematic investigations of equatorial electrodynamics. Plain Language SummaryIt is well-known that the ionospheric equatorial zonal electric fields of the Earth play a key role in the generation and development of all the large-scale coupled equatorial-and low-latitude processes. Thus, knowledge of the equatorial electric fields is essential for comprehensive investigations of the equatorial-and low-latitude upper atmospheric behavior. This information on equatorial electric fields can be obtained directly by measuring the vertical drift of plasma above the magnetic equator. The vertical drifts are conventionally measured by ground-based radars and space-based payloads. In this work, a novel technique to estimate the daytime equatorial vertical drifts is presented using ground-based optical dayglow emission measurements. The estimated drifts match well with the model estimates and both ground-and space-borne observations as reported in the published literature. This method of estimating vertical drifts can be used to carry out continuous and systematic investigations of the equatorial electrodynamics. To the best of our knowledge, such a possibility of deriving the daytime equatorial vertical drifts using ground-based optical methods has not been shown before.

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Observations of the generation of eastward equatorial electric fields near dawn

Cited by 19 publications

References 27 publications

The dawn enhancement of the equatorial ionospheric vertical plasma drift

The dawn enhancement of the equatorial ionospheric vertical plasma drift

Analysis of local ionospheric variability based on SVD and MDS at low-latitude GNSS stations

On Estimation of Daytime Equatorial Vertical (E × B) Plasma Drifts Using Optical Neutral Dayglow Emission Measurements

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