Observations of GPS ionospheric scintillations over Wuhan during geomagnetic storms

Li, Guozhu; Ning, Baiqi; Wan, Weixing

doi:10.5194/angeo-24-1581-2006

Cited by 29 publications

(15 citation statements)

References 38 publications

(23 reference statements)

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“…It is known that, besides TIDs, ionospheric irregularities in EIA region can also cause variations in electron density and thus influence the propagation of LSTIDs. However, in the present study, we calculated the rate of TEC index (ROTI), and found that no ionospheric irregularities occurred between 1500 and 1600 UT in South China, although such irregularities were previously observed there during storms [ Li et al , 2006, 2009].…”

Section: Discussionmentioning

confidence: 51%

Two‐dimensional imaging of large‐scale traveling ionospheric disturbances over China based on GPS data

et al. 2012

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[1] This paper reports the first results of the 2D imaging of large-scale traveling ionospheric disturbances (LSTID) using GPS network data from China, combined with observations of these events using an ionosonde chain. 2D TEC perturbation maps for North America were also constructed to allow the study of LSTIDs on a global scale. During the medium storm on 28 May 2011, the onset of a substorm initiated a slow-speed LSTID over North America just after midnight. Subsequently, an LSTID reached China 1.5 hours later, at dusk. A second LSTID was observed over China before midnight, 6.6 hours after substorm onset. The phase fronts of the China events had a front width of at least 1600 km, and moved southwestwards at a speed of 540 AE 85 m/s and 362 AE 89 m/s, respectively. Ionosonde data addressed a downward vertical phase velocity of $75 m/s for the dusk event and $60 m/s for the night event. Although the nighttime LSTID travelled farther south than the earlier dusk event, both disappeared in South China, and this was due to increase of the attenuation at low latitudes. According to the energy dissipation equation of atmospheric gravity waves there is severe dissipation due to viscosity and heat conductivity at low latitudes, since such dissipation increases strongly with time; dissipation due to ion drag is less important but cannot be ignored because of enhancement in background TEC; In addition, uplift of the ionosphere at low latitudes is another factor that results in a reduced amplitude of TEC perturbation at low latitudes.

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Section: Discussionmentioning

confidence: 51%

Two‐dimensional imaging of large‐scale traveling ionospheric disturbances over China based on GPS data

et al. 2012

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“…Recently, the GPS ionospheric scintillations at a low-middle latitude station Wuhan in China during storms were studied (Li et al, 2006;Xu et al, 2006Xu et al, , 2007. In the present study, GPS scintillation/TEC measurements at Sanya (18.31N, 109.51E), Digisonde and DMSP plasma density data from other longitude sectors are utilized to study the effects of geomagnetic storms on equatorial ionospheric scintillations during the low scintillation occurrence season (for station Sanya, the GPS ionospheric scintillations mainly occur during equinoctial months (3,4,9,10), and are rarely observed at solstice).…”

Section: Introductionmentioning

confidence: 99%

Effects of geomagnetic storm on GPS ionospheric scintillations at Sanya

Li¹,

Ning²,

Zhao³

et al. 2008

Journal of Atmospheric and Solar-Terrestrial Physics

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“…Accordingly, in the categories I and II, occurrence of Es layer at the low-latitude station at Hyderabad and equatorial spread-F occurrence at the Tirunelveli in the recovery phases of storms show the anticorrelation. Li et al (2006) suggested that Es layers at low latitude caused inhibition of GPS L-band scintillations on the two of the storms they have investigated. The presence of Es layer in the evening hour can modify the longitudinal/local time gradient in the E-region integrated Pederson conductivity that can affect the intensity of PRE development (Carrasco et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…In this study, a total of 73 moderate to intense geomagnetic storm events are identified and classified them into three categories according to Aarons (1991) criteria, which is commonly accepted criteria to explore the occurrence of ionospheric irregularities. It is believed that low-latitude Es layers may be modified due to modified winds/electric fields during the geomagnetic storms, and hence, examining their role in the generation of ESF irregularities is very important (e.g., Li et al, 2006;Sripathi et al, 2018). (2) Category II: if the maximum negative of Dst occurs during the midnight-down (at 00:00-06:00 LT), the height of the ionospheric F layer first rises and then falls, which generated the ionospheric irregularities.…”

Section: Introductionmentioning

confidence: 99%

A Statistical Study on The Local Time Dependence of Equatorial Spread F (ESF) Irregularities and Their Relation to Low‐Latitude Es Layers Under Geomagnetic Storms

Singh

Sripathi

2020

JGR Space Physics

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In this paper, we present a study on the local time dependence of equatorial spread F (ESF) irregularities and their relation to low-latitude Es layers in response to geomagnetic storms using simultaneous observations of two ionosondes one located at Tirunelveli (8.73°N, 77.70°E), an equatorial station and other located at Hyderabad (17.36°N, 78.47°E), an off-equatorial station during the years 2007-2015 that covers solar cycles 23 and 24. The Aarons criteria for the ESF irregularities for different seasons under geomagnetic storms are evaluated. In the category I, we noticed partial enhancement in prereversal enhancement (PRE) during postsunset resulting in~30% occurrence of spread F instead of total inhibition during equinox and winter seasons. Also, occurrence of ESF in summer is suppressed by onlỹ 75% due to partial increase in PRE. In category II, we observed presunrise height enhancement mostly during winter, which caused ESF to occur at~50% followed by equinox and summer. The results presented here suggest that many are actually not following the Aarons criteria possibly due to not considering other background conditions. Accordingly, we examined the plausible role of low-latitude Es layers on the generation of ESF irregularities under these categories during geomagnetic storms. We noticed the absence/presence of Es layers in both categories during postsunset and postmidnight hours resulting in increase/decrease of PRE due to modifications in the field-line-integrated Pederson conductivity. Accordingly, the results suggest that one of the plausible reasons for ESF irregularities not following Aarons criteria is linked to the variability of the low-latitude Es layers. Plain Language SummaryThe electric fields and winds in the equatorial and low-latitude ionosphere are modified during geomagnetic storms due to coupling of solar wind-magnetosphereionosphere in the high latitudes. Accordingly, the occurrence of equatorial spread F (ESF) irregularities are significantly affected by the geomagnetic storms depending upon the time of the onset of the geomagnetic storm. We classified our observations into three categories based on Aarons criteria under different seasons to examine the role of geomagnetic storms on the generation/suppression of ESF irregularities based on the onset conditions of magnetic storms over India. The observations suggest that many ESF events could not follow this criterion due to not having included other background conditions. Accordingly, we examined the role of low-latitude Es layers, which may affect the field-integrated conductivities of the E and F regions during the onset times of ESF irregularities using larger data. The results suggest that whenever Es layers are present (absent) at low latitude, suppression (generation) of premidnight or postmidnight ESF irregularities at Tirunelveli is on rise. So these results suggest that if the low-latitude Es layers are taken into account, occurrence of ESF irregularities may be explained better by the above criteria.

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Observations of GPS ionospheric scintillations over Wuhan during geomagnetic storms

Cited by 29 publications

References 38 publications

Two‐dimensional imaging of large‐scale traveling ionospheric disturbances over China based on GPS data

Two‐dimensional imaging of large‐scale traveling ionospheric disturbances over China based on GPS data

Effects of geomagnetic storm on GPS ionospheric scintillations at Sanya

A Statistical Study on The Local Time Dependence of Equatorial Spread F (ESF) Irregularities and Their Relation to Low‐Latitude Es Layers Under Geomagnetic Storms

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