Irregular Phenomena in Magnetically Conjugate Regions of the F2 Layer of the Ionosphere

Sergeenko, N. P.

doi:10.1134/s0016793218060166

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…This change in the altitude of the maximum concentration increase with latitude suggests that the conjugate effect of the eclipse is also affected by the EIA and the fountain effect. These increases and altitudes are in agreement with previous observations and models of TEC at conjugate locations during eclipses (He et al, 2018; Huba & Drob, 2017; Le, Liu, Yue, Wan, & Ning, 2009; Sergeenko, 2018). In particular, the model of Huba and Drob (2017) suggests that these effects can be explained by a change in conductivity derived from the reduced solar radiation in the area of obscuration, leading to a modification of the electrostatic potential that is being reflected through field lines in the opposite hemisphere.…”

Section: Discussionsupporting

confidence: 92%

First Report of an Eclipse From Chilean Ionosonde Observations: Comparison With Total Electron Content Estimations and the Modeled Maximum Electron Concentration and Its Height

et al. 2020

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The ionospheric responses to the total solar eclipse on 2 July 2019 over low latitudes in southern South America are presented. Ionosonde observations were used within the totality path at La Serena (LS: 29.9°S, 71.3°W) and at Tucumán (TU: 26.9°S, 65.4°W) and Jicamarca (JI: 12.0°S, 76.8°W), with 85% and 52% obscuration, respectively. Total electron content (TEC) estimations over the South American continent were analyzed. The ionospheric impact of the eclipse was simulated using the Sheffield University Plasmasphere-Ionosphere Model (SUPIM) at the Instituto Nacional de Pesquisas Espaciais (INPE). The significant variability of the diurnal variations of the various ionospheric characteristics over equatorial and low latitudes on geomagnetically quiet days makes it difficult to unambiguously determine the ionospheric responses to the eclipse. Nonetheless, some specific issues can be derived, mainly using simulation results. The E and F1 layer critical frequencies and densities below 200 km are found to consistently depend on decreasing solar radiation. However, the F1 layer stratification observed at both TU and LS cannot be related to the eclipse or other processes. The F2 layer does not follow the changes in direct solar radiation during the eclipse. The SUPIM-INPE-modeled F region critical frequency and TEC are overestimated before the eclipse at LS and particularly at TU. However, these overestimations are within the observed large day-today variability. When an artificial prereversal enhancement is added, the simulations during the eclipse better reproduce the observations at JI, are qualitatively better for LS, and are out of phase for TU. The simulations are consistent with conjugate location effects.

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Section: Discussionsupporting

confidence: 92%

First Report of an Eclipse From Chilean Ionosonde Observations: Comparison With Total Electron Content Estimations and the Modeled Maximum Electron Concentration and Its Height

et al. 2020

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“…On the other hand, our results show a much large concentration decrease at conjugate locations after the eclipse maximum obscuration, as shown in the TEC (Figure 3). Small-amplitude TEC increases prior to much larger depletions were previously found at conjugates (He et al, 2018;Huba & Drob, 2017;Sergeenko, 2018). Results also show a T e cooling along the magnetic meridian up to the Northern Hemisphere, in agreement with Huba and Drob (2017).…”

Section: 1029/2020ja028625supporting

confidence: 82%

“…These conjugate temperature decreases are originated by the photoelectron heating reduction induced by the solar obscuration. Above 300 km, the large thermal conductivity of photoelectrons along magnetic field lines allows their transfer between hemispheres, reducing the temperatures along these lines (Huba & Drob, 2017; Le, Liu, Yue, Wan, & Ning, 2009; Sergeenko, 2018).…”

Section: Resultsmentioning

confidence: 99%

Prediction of the Ionospheric Response to the 14 December 2020 Total Solar Eclipse Using SUPIM‐INPE

et al. 2020

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We present the first prediction of the ionospheric response to the 14 December 2020 solar eclipse using the SUPIM-INPE model. Simulations are made for all known ionosonde stations for which solar obscuration is significant. The found response is similar to that previously reported for other eclipses, but it also shows a modification of the equatorial fountain transport that will impact the low latitudes after the event. In addition to the large reduction of electron concentration along the totality path (~4.5 TECu, 22%), a significant electron and oxygen ion temperature cooling is observed (up to~400 K) followed by lasting temperature increases. Changes of up to~1.5 TECu (~5%) are also expected at the conjugate hemisphere. These predictions may serve as a reference for eventual ionospheric measurements of multiple instruments and are leading to a better understanding of the ionospheric response to solar eclipses.

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“…The decrease in foF2 and hmF2 is notorious at stations near the anomaly's crest (RA, FZ, CP); however, it is not very significant in the stations at the magnetic equator (SL). Moreover, similar ionospheric effects were seen in distant regions in the moon's shadow [16][17][18][19][20][51][52][53][54][55][56]. Differences between foF2 and TEC may be due to the fact that foF2 was the result of the original autoscaled records, and also that TEC was calculated from a spatial average.…”

Section: Ionospheric Behaviormentioning

confidence: 85%

Ionospheric Behavior during the 10 June 2021 Annular Solar Eclipse and Its Impact on GNSS Precise Point Positioning

et al. 2022

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The main effects of the 10 June 2021 annular solar eclipse on GNSS position estimation accuracy are presented. The analysis is based on TEC measurements made by 2337 GNSS stations around the world. TEC perturbations were obtained by comparing results 2 days prior to and after the day of the event. For the analysis, global TEC maps were created using ordinary Kriging interpolation. From TEC changes, the apparent position variation was obtained using the post-processing kinematic precise point positioning with ambiguity resolution (PPP-AR) mode. We validated the TEC measurements by contrasting them with data from the Swarm-A satellite and four digiosondes in Central/South America. The TEC maps show a noticeable TEC depletion (<−60%) under the moon’s shadow. Important variations of TEC were also observed in both crests of the Equatorial Ionization Anomaly (EIA) region over the Caribbean and South America. The effects on GNSS precision were perceived not only close to the area of the eclipse but also as far as the west coast of South America (Chile) and North America (California). The number of stations with positioning errors of over 10 cm almost doubled during the event in these regions. The effects were sustained longer (∼10 h) than usually assumed.

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Irregular Phenomena in Magnetically Conjugate Regions of the F2 Layer of the Ionosphere

Cited by 4 publications

References 9 publications

First Report of an Eclipse From Chilean Ionosonde Observations: Comparison With Total Electron Content Estimations and the Modeled Maximum Electron Concentration and Its Height

First Report of an Eclipse From Chilean Ionosonde Observations: Comparison With Total Electron Content Estimations and the Modeled Maximum Electron Concentration and Its Height

Prediction of the Ionospheric Response to the 14 December 2020 Total Solar Eclipse Using SUPIM‐INPE

Ionospheric Behavior during the 10 June 2021 Annular Solar Eclipse and Its Impact on GNSS Precise Point Positioning

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