First observation of interhemispheric asymmetry in the EPBs during the St. Patrick's Day geomagnetic storm of 2015

Sau, Sukanta; Narayanan, Viswanathan Lakshmi; Gurubaran, S.; Ghodpage, R. N.; Patil, P. T.

doi:10.1002/2017ja024213

Cited by 15 publications

(25 citation statements)

References 39 publications

(58 reference statements)

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“…The zonal drift again turned westward at ~18:15 UT and continued till 20:15 UT as recorded by CADI. We corroborate with Sau et al () and suggest that the weakening of westward drift in the premidnight period is due to the recovery process of main phase step‐I before the initiation of the step‐II. It is also suggested, here, that the commencement of main phase step‐II resurges the disturbance wind dynamo, which on its arrival at low latitudes causes the westward drift till 20:20 UT.…”

Section: Discussionsupporting

confidence: 92%

“…The IMF B z is observed to be northward during this period (Figure 1 of Huang et al, ). Sau et al () reported the westward drift reduction during this period as measured by the imager and attributed it to this temporary SYM‐H recovery. Our observations also demonstrate the reduction in westward zonal plasma drift and its eastward turning at ~18:00 UT for a short period of time.…”

Section: Discussionmentioning

confidence: 76%

“…During this storm, the presence of nighttime DDE field (eastward) over the Indian longitudes has been reported extensively (e.g., Patra et al, 2016;Sau et al, 2017, and references therein). In particular, Sau et al (2017) presented westward equatorial plasma bubble velocity between 16:00 and 21:00 UT using Airglow imager measurements from the same location of Tirunelveli and discussed in terms of the eastward manifestations of DDE field over the Indian longitudes. Therefore, despite the eastward DDE field, the observed vertical downward drift between 17:00 and 17:50 UT suggests the dominance of PPE field over the prevailing DDE field during this period.…”

Section: 1002/2017ja024703mentioning

confidence: 99%

See 2 more Smart Citations

On the Nocturnal Downward and Westward Equatorial Ionospheric Plasma Drifts During the 17 March 2015 Geomagnetic Storm

Bagiya¹,

Vichare²,

Sinha³

et al. 2018

JGR Space Physics

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During quiet period, the nocturnal equatorial ionospheric plasma drifts eastward in the zonal direction and downward in the vertical direction. This quiet time drift pattern could be understood through dynamo processes in the nighttime equatorial ionosphere. The present case study reports the nocturnal simultaneous occurrence of the vertically downward and zonally westward plasma drifts over the Indian latitudes during the geomagnetic storm of 17 March 2015. After ~17:00 UT (~22:10 local time), the vertical plasma drift became downward and coincided with the westward zonal drift, a rarely observed feature of low latitude plasma drifts. The vertical drift turned upward after ~18:00 UT, while the zonal drift became eastward. We mainly emphasize here the distinct bipolar type variations of vertical and zonal plasma drifts observed around 18:00 UT. We explain the vertical plasma drift in terms of the competing effects between the storm time prompt penetration and disturbance dynamo electric fields. Whereas, the westward drift is attributed to the storm time local electrodynamical changes mainly through the disturbance dynamo field in addition to the vertical Pedersen current arising from the spatial (longitudinal) gradient of the field aligned Pedersen conductivity.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 76%

Section: 1002/2017ja024703mentioning

confidence: 99%

See 1 more Smart Citation

On the Nocturnal Downward and Westward Equatorial Ionospheric Plasma Drifts During the 17 March 2015 Geomagnetic Storm

Bagiya¹,

Vichare²,

Sinha³

et al. 2018

JGR Space Physics

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“…The panels of figure 11 from top to bottom represent the stations LHAZ, LCK4, WALT, HYDE, IISC and SGOC, respectively. Except for LHAZ, all stations show strong fluctuations in ROTI during 13:30 to 21:30 UT (19:00 to 03:00 IST), which is consistent with the previous studies over Indian region (Ramsingh Sripathi et al 2015;Tulasi Ram et al 2015;Kakad et al 2016;Patra et al 2016;Nayak et al 2017;Sau et al 2017). LHAZ lies around 90 • E longitude also beyond the northern EIA region, and this may be one of the reasons for the absence of fluctuations in ROTI.…”

Section: L-band Scintillation Of Gps and Glonass Constellationssupporting

confidence: 90%

L-band scintillation and TEC variations on St. Patrick’s Day storm of 17 March 2015 over Indian longitudes using GPS and GLONASS observations

et al. 2019

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The aim of the present study is to investigate the response of ionospheric total electron content (TEC), Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) scintillations during 17 March 2015 St. Patrick's Day geomagnetic storm over Visakhapatnam, which is popularly known as Waltair (WALT) in the literature. GPS TEC observations obtained from five IGS stations (SGOC, IISC, HYDE, LCK4 and LHAZ) and WALT during the storm have been compared. The TEC derived from GPS, GLONASS constellations and CODE global ionosphere TEC map (GIM) over WALT has also been compared. Positive storm effect during the main phase of the storm and negative storm effect during the recovery phase of the storm were observed over the said stations. The variation of northern equatorial ionisation anomaly TEC (CODE GIM TEC maps) in response to the St. Patrick's Day storm over four Indian longitudes (75 • E, 80 • E, 85 • E and 90 • E) has also been presented. Strong amplitude and phase scintillations were observed in the L-band signals of GPS and GLONASS constellations over WALT. Twelve satellite (Pseudo Random Noise) PRNs of GPS L1 and nine PRNs of each GLONASS L1 and L2-band signals were affected by strong amplitude and phase scintillation. The peak amplitude scintillation index (S4) obtained from the effected PRNs of GPS L1 signal and GLONASS L1-band signals over WALT range from 0.36 to 0.74 and 0.36 to 0.76, respectively. Strong fluctuations in rate of TEC index are noted over the said stations. This enhanced scintillation activity is mainly due to the main phase of the storm falls in the evening sector over the Indian region.

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“…Different mechanisms have been proposed to explain spread-F occurrences and their development (Bowman 1990;Fejer et al 1999;Fukao et al 2004); among these, the primary mechanism in equatorial regions is the generalized Rayleigh-Taylor (R-T) instability mechanism. The R-T instability mechanism suggests that pre-reversal electric field enhancements (PRE) during the evening cause a rapid uplift of the ionosphere's F-layer Fukao et al 2004;Manju et al 2007;Sukanta et al 2017;Xiong et al 2012;Upadhayaya and Gupta 2014). Relationships between spread-Fs and other ionospheric parameters, particularly the F2-layer (foF2) and h′F variations with the occurrence of spread-Fs, have also been statistically examined (Rungraengwajiake et al 2013;Joshi et al 2013;Madhav Haridas et al 2013;de Abreu et al 2014ade Abreu et al , b, c, 2017Abadi et al 2015;Manju and Madhav Haridas 2015;Smith et al 2015;Liu and Shen 2017).…”

Section: Introductionmentioning

confidence: 99%

Spread-F occurrences and relationships with foF2 and h′F at low- and mid-latitudes in China

Wang

Guo

Zhao

et al. 2018

Earth Planets Space

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Ionospheric irregularities are an important phenomenon in scientific studies and applications of radio-wave propagation. Spread-F echoes in ionograms are a type of high-frequency band irregularities that include frequency spread-F (FSF), range spread-F (RSF), and mixed spread-F (MSF) events. In this study, we obtained spread-F data from four ionosondes at low-and mid-latitudes near the 120°E chain in China during the 23rd solar cycle. We used these data to investigate spread-F occurrence percentages and variations with local time, season, latitude, and solar activity. The four ionosondes were located at Haikou (HK) (20°N, 110.34°E), Guangzhou (GZ) (23.14°N, 113.36°E), Beijing (BJ) (40.11°N, 116.28°E), and Changchun (CC) (43.84°N, 125.28°E). We also present possible correlations between spread-Fs and other ionospheric parameters, such as the critical frequency of the F2-layer (foF2) and the virtual height of the bottom-side F-layer (h′F). In particular, we investigated the possible threshold of the foF2 affecting the FSF and the relationship between the h′F and the RSF. The main conclusions are as follows: (a) the FSF occurrence percentages were anti-correlated with solar activity at all four sites; meanwhile, RSF occurrence rates increased with the increase in solar activity at HK, but not at the other three sites; (b) FSF occurrence rates were larger at the mid-latitudes than expected, while FSFs occurred more often after midnight; (c) the highest FSF occurrence rates mostly appeared during the summer months, while RSFs occurred mostly in the equinoctial months of 2000-2002 at HK and GZ; (d) a lower foF2 was suitable for FSF events; nevertheless, h′F and RSF occurrences satisfied the parabolic relationship; (e) the foF2 thresholds for FSFs were 15, 14, 7.6, and 7.8 MHz at HK, GZ, BJ, and CC, respectively. The h′Fs occurring between 240 and 290 km were more favorable for RSF occurrences. These results are important for understanding ionospheric irregularity variations in eastern Asia and for improving space weather modeling and forecasting capabilities .

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First observation of interhemispheric asymmetry in the EPBs during the St. Patrick's Day geomagnetic storm of 2015

Cited by 15 publications

References 39 publications

On the Nocturnal Downward and Westward Equatorial Ionospheric Plasma Drifts During the 17 March 2015 Geomagnetic Storm

On the Nocturnal Downward and Westward Equatorial Ionospheric Plasma Drifts During the 17 March 2015 Geomagnetic Storm

L-band scintillation and TEC variations on St. Patrick’s Day storm of 17 March 2015 over Indian longitudes using GPS and GLONASS observations

Spread-F occurrences and relationships with foF2 and h′F at low- and mid-latitudes in China

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