Ionospheric Total Electron Content Response to the Great American Solar Eclipse of 21 August 2017

Cherniak, Iurii; Zakharenkova, Irina

doi:10.1002/2017gl075989

Cited by 72 publications

(75 citation statements)

References 19 publications

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“…Another remarkable variation seen in Figure 3 was a quick recovery from the eclipse and a large Ne increase that commenced soon after the eclipse, peaking at 23-24 UT. A similar posteclipse increase above the background value was reported in several studies of the 21 August 2017 solar eclipse over many locations across North America (Chen et al, 2018;Cherniak & Zakharenkova, 2018;Nayak & Yigit, 2018;Reinisch et al, 2018), though the TEC increase is weaker in general as it reflects the integrated Ne response over all altitudes. Mechanisms that contribute to a quick recovery and Ne increase after 21 UT could include disturbances in the neutral wind and O/N2 ratio (Chen et al, 2018;Muller-Wodarg et al, 1998).…”

Section: A Summary Of the Midlatitude Electron Density (Ne) Vertical supporting

confidence: 82%

Ionospheric Response to the Solar Eclipse of 21 August 2017 in Millstone Hill (42N) Observations

Гончаренко

Erickson

Zhang

et al. 2018

Geophysical Research Letters

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This study examines the ionospheric changes associated with the solar eclipse of 21 August 2017. The effects associated with the passage of the eclipse shadow were observed more than 1,000 km away from the totality at midlatitudes using the Millstone Hill incoherent scatter radar and digisonde. There was a 30–40% decrease in electron density, a 100‐ to 220‐K decrease in electron temperature, and a 50‐ to 140‐K decrease in ion temperature. Surprisingly, the greatest decrease in electron density occurred above 200 km. The most unexpected effect was a large 20‐ to 40‐m/s upward vertical drift observed in the topside ionosphere right after the local maximum obscuration. We suggest that this drift led to a posteclipse increase in the topside electron density.

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Section: A Summary Of the Midlatitude Electron Density (Ne) Vertical supporting

confidence: 82%

Ionospheric Response to the Solar Eclipse of 21 August 2017 in Millstone Hill (42N) Observations

Гончаренко

Erickson

Zhang

et al. 2018

Geophysical Research Letters

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“…This makes the GPS-based TEC indeed more similar to the radar-based TEC for the control case, so it is clear that the difference in control day contributes to the discrepancy between the observational data sets. We note that another study of GPS-based TEC responses to the eclipse by Cherniak and Zakharenkova (2018) used a different reference case from Coster et al (2017), namely, the mean of 20 and 22 August 2017, and also found generally smaller TEC reductions than Coster et al (2017). The difference in TEC between 22 and 29 August 2017 is probably due to differences in geomagnetic activity: 18-23 August 2017 was a geomagnetically active period, while conditions were much quieter on 29 August 2017.…”

Section: Comparison To Observationsmentioning

confidence: 72%

“…There are two key differences between the observational data sets that probably explain most of the discrepancy. We note that another study of GPS-based TEC responses to the eclipse by Cherniak and Zakharenkova (2018) used a different reference case from Coster et al (2017), namely, the mean of 20 and 22 August 2017, and also found generally smaller TEC reductions than Coster et al (2017). Based on a typical electron density profile, this could explain a difference on the order of around 25% (González-Casado et al, 2015).…”

Section: Comparison To Observationsmentioning

confidence: 76%

“…For instance, it seems unlikely that the posteclipse enhancement in the electron density can be explained by noneclipse effects, given that several other studies have reported similar posteclipse effects, both for this eclipse (e.g., Cherniak & Zakharenkova, 2018;Wu et al, 2018) and previous events (e.g., Chen et al, 2013). This also explains why there are signatures present in the observations already before the actual start of the partial eclipse: These are differences between 21 and 22 August 2017 that are unrelated to the eclipse.…”

Section: Comparison To Observationsmentioning

confidence: 93%

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The Response of the Ionosphere‐Thermosphere System to the 21 August 2017 Solar Eclipse

et al. 2019

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We simulated the effects of the 21 August 2017 total solar eclipse on the ionosphere‐thermosphere system with the Global Ionosphere Thermosphere Model (GITM). The simulations demonstrate that the horizontal neutral wind modifies the eclipse‐induced reduction in total electron content (TEC), spreading it equatorward and westward of the eclipse path. The neutral wind also affects the neutral temperature and mass density responses through advection and the vertical wind modifies them further through adiabatic heating/cooling and compositional changes. The neutral temperature response lags behind totality by about 35 min, indicating an imbalance between heating and cooling processes during the eclipse, while the ion and electron temperature responses have almost no lag, indicating they are in quasi steady state. Simulated ion temperature and vertical drift responses are weaker than observed by the Millstone Hill Incoherent Scatter Radar, while simulated reductions in electron density and temperature are stronger. The model misses the observed posteclipse enhancement in electron density, which could be due to the lack of a plasmasphere in GITM. The simulated TEC response appears too weak compared to Global Positioning System TEC measurements, but this might be because the model does not include electron content above 550‐km altitude. The simulated response in the neutral wind after the eclipse is too weak compared to Fabry Perot interferometer observations in Cariri, Brazil, which suggests that GITM recovers too quickly after the eclipse. This could be related to GITM heating processes being too strong and electron densities being too high at low latitudes.

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“…Le et al (2010) related the valley of electron density distribution during the eclipse phases to the contraction/compression and expansion of the atmosphere brought by the decrease and increase in temperature. Chukwuma and Adekoya (2016) attributed the decrease in the electron temperature to the downward vertical trans-port process and the decrease in the cooling process to the upward vertical transport process. Figure 3 describes the variation in H m , B1 and B0 in three columns respectively for all the stations.…”

Section: Resultsmentioning

confidence: 99%

Solar-eclipse-induced perturbations at mid-latitude during the 21 August 2017 event

et al. 2019

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A study of the response of some ionospheric parameters and their relationship in describing the behaviour of ionospheric mechanisms during the solar eclipse of 21 August 2017 is presented. Mid-latitude stations located along the eclipse path and with data available from the Global Ionospheric radio Observatory (GIRO) database were selected. The percentage of obscuration at these stations ranges between 63 % and 100 %. A decrease in electron density during the eclipse is attributed to a reduction in solar radiation and natural gas heating. The maximum magnitude of the eclipse consistently coincided with a hmF2 increase and with a lagged maximum decrease in NmF2 at the stations investigated. The results revealed that the horizontal neutral wind flow is as a consequence of the changes in the thermospheric and diffusion processes. The unusual increase and decrease in the shape and thickness parameters during the eclipse period relative to the control days points to the perturbation caused by the solar eclipse. The relationships of the bottomside ionosphere and the F2 layer parameters with respect to the scale height are shown in the present work as viable parameters for probing the topside ionosphere during the eclipse. Furthermore, this study shows that in addition to traditional ways of analysing the thermospheric composition and neutral wind flow, proper relation of standardized NmF2 and hmF2 can be conveniently used to describe the mechanisms.

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Ionospheric Total Electron Content Response to the Great American Solar Eclipse of 21 August 2017

Cited by 72 publications

References 19 publications

Ionospheric Response to the Solar Eclipse of 21 August 2017 in Millstone Hill (42N) Observations

Ionospheric Response to the Solar Eclipse of 21 August 2017 in Millstone Hill (42N) Observations

The Response of the Ionosphere‐Thermosphere System to the 21 August 2017 Solar Eclipse

Solar-eclipse-induced perturbations at mid-latitude during the 21 August 2017 event

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