Evidence for the Influence of DE3 Tide on the Occurrence of Equatorial Counterelectrojet

Singh, Dupinder; Gurubaran, S.; He, Maosheng

doi:10.1002/2018gl077076

Cited by 20 publications

(24 citation statements)

References 40 publications

(60 reference statements)

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“…The EEJ intensity sharply decreases from 90°W to 40°W, and the global analysis of Swarm data suggest that this longitudinal gradient is partly due to the wave‐4 longitudinal structure arising from nonmigrating tides and stationary planetary waves. The wave‐4 effect is found not only in ACEJ, as recently reported by Singh et al (), but also in MCEJ. TIEGCM results suggest that the longitudinal variation of the EEJ intensity resulting from migrating tides also makes a contribution to the observed longitudinal gradient of the EEJ intensity over the American sector. Both the effects of migrating tides (across the longitudinally varying geomagnetic main field) and wave‐4 pattern are of similar size and, combined, lead to a stronger EEJ in the Peruvian sector than in the Brazilian sector during the northern‐hemisphere summer, resulting in higher CEJ occurrence rates in the Brazilian sector.…”

Section: Discussionsupporting

confidence: 81%

“…Singh et al () showed that the DE3 tide gives rise to the wave‐4 longitudinal pattern in the occurrence rate of ACEJ. Our results suggest that the wave‐4 longitudinal pattern is also an important source of longitudinal variability for the MCEJ occurrence rate.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, Singh et al () used magnetometer data from the Challenging Minisatellite Payload satellite and zonal wind observations from the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite to demonstrate that the occurrence rate of ACEJ on a global scale is strongly influenced by the DE3 tidal mode during July–September months. They observed longitudinal sectors of high ACEJ occurrence that coincide with regions of eastward DE3 tidal winds.…”

Section: Introductionmentioning

confidence: 99%

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Equatorial Counter Electrojet Longitudinal and Seasonal Variability in the American Sector

et al. 2018

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The equatorial electrojet occasionally reverses during morning and afternoon hours, leading to periods of westward current in the ionospheric E region that are known as counter electrojet (CEJ) events. We present the first analysis of CEJ climatology and CEJ dependence on solar flux and lunar phase for the Brazilian sector, based on an extensive ground-based data set for the years 2008 to 2017 from the geomagnetic observatory Tatuoca (1.2°S, 48.5°W), and we compare it to the results found for Huancayo (12.0°S, 75.3°W) observatory in the Peruvian sector. We found a predominance of morning CEJ events for both sectors. The afternoon CEJ occurrence rate in the Brazilian sector is twice as high as in the Peruvian sector. The afternoon CEJ occurrence rate strongly depends on season, with maximum rates occurring during the northern-hemisphere summer for the Brazilian sector and during the northern-hemisphere winter for the Peruvian sector. Significant discrepancies between the two sectors are also found for morning CEJ rates during the northern-hemisphere summer. These longitudinal differences are in agreement with a CEJ climatology derived from contemporary Swarm satellite data and can be attributed in part to the well-known longitudinal wave-4 structure in the background equatorial electrojet strength that results from nonmigrating solar tides and stationary planetary waves. Simulations with the Thermosphere-Ionosphere-Electrodynamics General Circulation Model show that the remaining longitudinal variability in CEJ during northern summer can be explained by the effect of migrating tides in the presence of the varying geomagnetic field in the South Atlantic Anomaly.The quiet-time CEJ is mainly related to changes in the atmospheric tides that dominate the global wind system at ionospheric heights (Gurubaran, 2002;Hanuise et al., 1983), and it is mostly observed during a few hours in the morning (MCEJ) or afternoon (ACEJ) periods. Under disturbed conditions, other mechanisms play a role in addition to the tidal variability, such as the prompt penetration of polar electric field into equatorial SOARES ET AL. 9906

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Equatorial Counter Electrojet Longitudinal and Seasonal Variability in the American Sector

et al. 2018

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“…The variability demonstrated at 5° separations in our study is direct evidence of the influence of short scale length processes. The other significant finding from our study is for the westward increase in CEJ amplitude and occurrence that have been attributed to wave‐tide interaction. We have shown that the same trend is evident for both quiet and disturbed periods indicating the pervasive influence of DE3 tide corroborated by Bulusu et al () and Singh et al ().…”

Section: Discussionsupporting

confidence: 89%

Constraints on Scale Lengths of Equatorial Electrojet and Counter Electrojet Phenomena From the Indian Sector

et al. 2018

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The present study investigates the longitudinal variability of equatorial electrojet (EEJ) and counter electrojet (CEJ) phenomena using concurrent data from three equatorial and low‐latitude paired stations/sites at 5°, 15°, and 20° longitudinal separation in the Indian sector: (i) Minicoy (72°E, dip latitude 01.32°) and Alibag (72°E, dip latitude 14.06°), (ii) Vencode (77°E, dip latitude 01.02°) and Hyderabad (77°E, dip latitude12.34°), and (iii) Campbell Bay (93°E, dip latitude −0.79°) and Nabagram (93°E, dip latitude 06.79°). The observations, over a period of 12 months, at 72°E and 77°E, and 10 months at 93°E, for the year 2015, reflect the variability in both amplitude and occurrence phenomena at close spatial scales. Significant day‐to‐day variability of EEJ and CEJ is observed, with increasing spatial separation. The closely spaced sites, MNC and VEN, show expected similarity but present striking differences in certain monthly averaged patterns. Concurrent observations from three longitudes reveal increasing EEJ amplitudes from west to east and a new observation of increasing CEJ amplitudes from east to west. From these longitudinal trends, we confirm that EEJ strengths are controlled by the large‐scale DE3 nonmigrating tide. A marked difference in CEJ amplitude between MNC and VEN suggests that scale lengths of CEJ and EEJ are different, and we infer that CEJ are primarily generated by short‐scale length variations in the middle atmosphere caused by localized interactions of planetary and gravity waves and are also influenced by the DE3 nonmigrating tide.

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“…Sometimes, the direction of the current reverses to westward, a phenomenon called counter electrojet (CEJ) due to a number of physical mechanisms including (but not limited to) ionospheric variability during stratospheric warming periods (Siddiqui et al, ; Stening et al, ; Vineeth et al, ), westward prompt penetrating electric field leading to ionospheric disturbed dynamo (Kikuchi et al, ; Yizengaw et al, ), and vertical upward winds uplifting ions thereby cancelling the vertical polarization electric field (Raghavarao & Anandarao, ). Therefore, the complex variability of CEJ is influenced/modulated by variations in local time, longitude (mainly related to migrating and nonmigrating tides), seasonal dependence, lunar cycles, magnetic activity, and solar activity (Marriott et al, ; Mayaud, ; Rabiu et al, ; Rastogi, ; Singh et al, ; Soares et al, ; Zhou et al, ). Since the CEJ's first detection (Gouin, ), various studies have investigated the CEJ occurrence based mainly on magnetometers deployed in equatorial and/or low‐latitude regions (e.g., Alex & Mukherjee, ; Rastogi, , and references therein).…”

Section: Introductionmentioning

confidence: 99%

Counter‐Electrojet Occurrence as Observed From C/NOFS Satellite and Ground‐Based Magnetometer Data Over the African and American Sectors

et al. 2019

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An analysis of the counter‐electrojet occurrence (CEJ) during 2008–2014 is presented for the African and American sectors based on local daytime (0700–1700 LT) observations from the Communications and Navigation Outage Forecasting System (C/NOFS) vertical ion plasma drift (equivalent to vertical E×B at an altitude of about 400 km) and ground‐based magnetometers. Using quiet time (Kp≤ 3) data, differences and/or similarities between the two data sets with reference to local time and seasonal dependence are established. For the first time, it is shown that C/NOFS satellite data are consistent with magnetometer observations in identifying CEJ occurrences during all seasons. However, C/NOFS satellite data show higher CEJ occurrence rate for almost all seasons. With respect to local time, C/NOFS satellite observes more CEJ events than magnetometer observations by average of about 20% and 40% over the American and African sectors, respectively, despite both data sets showing similar trends in CEJ identification. Therefore, when a space weather event occurs, it is important to first establish the original variability nature and/or magnitude of the eastward electric field in equatorial regions before attributing the resulting changes to solar wind‐magnetosphere and ionosphere coupling processes since CEJ events can be present even during quiet conditions.

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Evidence for the Influence of DE3 Tide on the Occurrence of Equatorial Counterelectrojet

Cited by 20 publications

References 40 publications

Equatorial Counter Electrojet Longitudinal and Seasonal Variability in the American Sector

Equatorial Counter Electrojet Longitudinal and Seasonal Variability in the American Sector

Constraints on Scale Lengths of Equatorial Electrojet and Counter Electrojet Phenomena From the Indian Sector

Counter‐Electrojet Occurrence as Observed From C/NOFS Satellite and Ground‐Based Magnetometer Data Over the African and American Sectors

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