Statistical Study of Ionospheric Equivalent Slab Thickness at Guam Magnetic Equatorial Location

Zhang, Yuqiang; Wu, Zhensen; Feng, Jing; Xu, Tong; Deng, Zixin; Ou, Ming; Xiong, Wen; Zhen, Weimin

doi:10.3390/rs13245175

Cited by 5 publications

(8 citation statements)

References 61 publications

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“…In addition, there are pre-sunrise and post-sunset peaks in winter in Beijing. Furthermore, the standard deviation of τ indicates that τ varies a lot at night and during the solar terminator hours, which agrees with previous studies [6,15,34,35]. As for the solar activity dependence of τ, Figure 4 presents the median and st deviation of τ during geomagnetic quiet-time in years of high-and low-solar-a Besides common features in high-and low-solar-activity years, there also exis differences between high-and low-solar-activity years as follows:…”

Section: Resultssupporting

confidence: 92%

“…In terms of the seasonal variation of τ at the same local time, daytime values are largest in summer and smallest in winter, while the opposite is true for nighttime values, which are greatest in winter and smallest in summer In addition, there are pre-sunrise and post-sunset peaks in winter in Beijing. Furthermore the standard deviation of τ indicates that τ varies a lot at night and during the solar terminator hours, which agrees with previous studies [6,15,34,35].…”

Section: Resultssupporting

confidence: 92%

“…Noting that this paper used the median of τ rather than the mean of τ to study the climatological of τ due to this could remove the outliers of the distribution, as Pignalberi et al [15] suggested. Moreover, in line with previous studies [34,35], we used the disturbance index (DI) to examine how geomagnetic storms affected τ and defined it as follows:…”

Section: Data and Methods Of Analysismentioning

confidence: 99%

“…In addition, the impact of magnetic activity on τ remains an unresolved issue due to its susceptibility to various spatial-temporal factors, such as local time, solar activity, and location. By defining the disturbance index (DI) of τ, we found that the τ usually tends to increase during storm-time at Guam equatorial station and Yakutsk high latitude station in East Asia [34,35]. However, the morphology of the DI index in midlatitudes of East Asia has not been studied.…”

Section: Introductionmentioning

confidence: 97%

“…Previous research has shown that the morphology of τ varies in different regions due to its unique dependence on the solar cycle, season, local times, and geomagnetic activity at each location [25][26][27][28][29][30][31][32][33][34][35]. In addition, the impact of magnetic activity on τ remains an unresolved issue due to its susceptibility to various spatial-temporal factors, such as local time, solar activity, and location.…”

Section: Introductionmentioning

confidence: 99%

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Statistical Study of the Ionospheric Slab Thickness at Beijing Midlatitude Station

et al. 2023

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The ratio of the total electron content (TEC) to the F2-layer peak electron density (NmF2) is known as the ionospheric equivalent slab thickness (EST, also known as τ), and it is a crucial indicator of the ionosphere. Using TEC and NmF2 data from the years 2010 to 2017, this work conducts a comprehensive statistical analysis of the ionospheric slab thickness in Beijing, which is in the midlatitude of East Asia. The outcomes show that the τ have different diurnal variations at different seasons for high/low-solar-activity years. On the whole, daytime τ significantly greater than nighttime τ in summer, and it is the opposite for the τ in winter regardless of the solar cycle, whereas the τ during equinox shows different morphology for high/low-solar-activity years. Specifically, daytime τ is larger than nighttime τ during equinox in years of high-solar activity, while the opposite situation applies for the τ during equinox in years of low-solar activity. Moreover, the pre-sunrise and post-sunset peaks are most pronounced during winter for low-solar-activity years. In summer, there is a great increase in τ during the morning hours when compared with other seasons. Furthermore, the τ decreases with the solar activity during nighttime, whereas it seems there is no correlation between daytime τ and solar activity. This paper explained the primary diurnal variations in τ across different seasons during high-/low-solar-activity years by analyzing relative fluctuations of TEC and NmF2 throughout the corresponding period. In addition, based on the disturbance index (DI), which is calculated by instantaneous τ and its corresponding median, this paper found that the storm-time τ might increase when compared with its median value during the daytime, while it may both increase and decrease during the nighttime, especially around dawn and dusk hours. To further analyze the physical mechanism, an example on 2 October 2013 is also presented. The results indicate that the positive disturbance of τ during the main phase of a geomagnetic storm might be caused by the prompt penetration electric field and neutral wind during the storm, and the τ increases during the early recovery phase might be due to the disturbance dynamo electric field as well as the neutral wind during the storm. Moreover, there is a negative disturbance of τ in the recovery phase during the most disturbed sunrise hours, and it might be due to the electric field reversal, neutral wind or other factors during this period. This paper notes the differences of τ in midlatitude between different longitudinal sectors from the related climatology and storm-time behavior, as it would be helpful to improve the current understanding of τ at midlatitudes in East Asia.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 92%

Section: Data and Methods Of Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Statistical Study of the Ionospheric Slab Thickness at Beijing Midlatitude Station

et al. 2023

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The Ionospheric Equivalent Slab Thickness: A Review Supported by a Global Climatological Study Over Two Solar Cycles

et al. 2022

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The ionospheric equivalent slab thickness ($\tau $ τ ) is a parameter characterizing both the distribution of the plasma in the ionosphere and the shape of the corresponding vertical electron density profile. It is calculated as the ratio of the vertical total electron content (vTEC) to the ionospheric F2-layer electron density maximum (NmF2). Since its definition dated back in the 60s, a lot of information on the behavior of $\tau $ τ for different helio-geophysical conditions has been cumulated and the connection with several plasma properties has been also demonstrated. The beginning of the Global Positioning System (GPS) era in the 90s had a strong effect on the studies about $\tau $ τ because GPS signals allow to obtain the vTEC up to about 20000 km of altitude. Recently, $\tau $ τ has also found application in many data-assimilation methodologies, especially for the improvement of empirical ionospheric models based on near real-time data. All of these topics are reviewed and discussed in this paper based on the literature published in the last sixty years.Moreover, to highlight and summarize the main global climatological features of $\tau $ τ , in this work we selected thirty-two ionospheric stations globally distributed and co-located with ground-based Global Navigation Satellite System (GNSS) receivers, for the last two solar cycles. This allowed to collect a dataset of NmF2 and vTEC that represents the largest and most complete ever analyzed for studies concerning $\tau $ τ , which gave the chance to deeply investigate its spatial, diurnal, seasonal, and solar activity variations. The corresponding results are presented and discussed in the light of the existing literature.

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Long-term relationships of ionospheric electron density with solar activity

Jakowski,

Hoque,

Mielich

2024

J. Space Weather Space Clim.

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Greenhouse gases such as carbon dioxide and methane that are causing climate change may cause long term trends in the thermosphere and ionosphere. The paper aims to contribute to explore long term effects in the ionosphere focusing on the impact of solar activity changes. Peak electron density data derived from vertical sounding measurements covering 65 years at the ionosonde stations Juliusruh (JR055), Boulder (BC840) and Kokubunji (TO536), have been utilized to estimate the long-term behavior of daytime ionospheric F2 layer ionization in relation to the solar 10.7 cm radio flux index F10.7. In parallel, Global Navigation Satellite System (GNSS) based vertical total electron content (TEC) data over the ionosonde stations in combination with the peak electron density data have been used to derive the equivalent slab thickness τ for estimating long-term behavior in the time period 1996-2022. A new approach has been developed for deriving production and loss term proxies for studying long-term ionization effects from F2 layer peak electron density and TEC data. The derived coefficients allow estimating the long-term variation of atomic oxygen and molecular nitrogen concentrations including their ratio during winter months. The noon-time slab thickness values over Juliusruh correlate well with the decrease of F10.7 and the F2 layer peak height and enable estimating the neutral gas temperature. The equivalent slab thickness decreases by about 20 km per decade in the period 1996-2022, indicating a thermospheric cooling by about 100 K per decade for Juliusruh. Whereas the oxygen concentration decreases, the loss term, considered as a proxy for molecular components of the neutral gas, in particular N2, increases with the long-term solar activity variation. Considering 11 years averages of the production and loss terms under wintertime conditions, the long-term study reveals for the O/N2 ratio a percentage decrease of 5% per decade and for F10.7 about 3.1% per decade in a linear approach referred to the year 1970. Linear models of 11 years averaged NmF2 and foF2 from corresponding F10.7 show a very close correlation with the temporal variation of F10.7 until about 1990. The root mean square errors are in the order of 1.0 -1.3 ‧1010m-3 for NmF2 and 0.03-0.05 MHz for foF2. After 1990 the linear models clearly deviate from F10.7 at all selected ionosonde stations indicating a non-local effect.

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Statistical Study of Ionospheric Equivalent Slab Thickness at Guam Magnetic Equatorial Location

Cited by 5 publications

References 61 publications

Statistical Study of the Ionospheric Slab Thickness at Beijing Midlatitude Station

Statistical Study of the Ionospheric Slab Thickness at Beijing Midlatitude Station

The Ionospheric Equivalent Slab Thickness: A Review Supported by a Global Climatological Study Over Two Solar Cycles

Long-term relationships of ionospheric electron density with solar activity

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