Modelling the peak of the ionospheric E-layer

Titheridge, J. E.

doi:10.1016/s1364-6826(99)00102-9

Cited by 55 publications

(81 citation statements)

References 32 publications

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“…Including this effect gives (Rishbeth and Garriott, 1969) f oE = A(cos χ) 0.25(1+g) (2) where g = d H/dh is the scale height gradient. Titheridge (2000) calculated the average value of scale height gradient which is 0.2 by the values of scale height derived from MSIS86 model between the height of 105 and 110 km. The same value was also obtained by empirical modeling (Muggleton, 1972b).…”

Section: Methods Descriptionmentioning

confidence: 99%

“…The result has been used in IRI (Bilitza, 1990). Constant value of diurnal exponent parameter was also adopted by Titheridge (2000) in his global empirical E-layer peak model. To simplify the form of our empirical model, we also use a constant value of B.…”

Section: Methods Descriptionmentioning

confidence: 99%

“…Most comparisons show that there was a good agreement between the observed and predicted f oE (or NmE) values. However, daytime values of NmE calculated by IRI model show some unexpected variations with latitude and season because of abrupt changes in the empirical equations or extrapolation of the equations into regions with little experimental data (Titheridge, 2000). Titheridge (1996Titheridge ( , 1997Titheridge ( , 2000 introduced a global E-layer peak model on the calculations with a full time-varying model.…”

Section: Introductionmentioning

confidence: 99%

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An empirical model of ionospheric foE over Wuhan

et al. 2006

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Daytime half-hourly values of the critical frequency of the ionospheric E-layer, f oE, obtained at Wuhan Ionospheric Observatory (geographic 114.4• E, 30.6 • N; 45.2 • dip), China, during the whole interval of 1957-1991 and 1999-2004 have been used to develop an empirical model. The model, including variations with local time, day number and solar cycle, is in agreement with the observations. A comparison between our model and IRI and Titheridge's model has also been made. Statistically, our model gives a better performance than IRI and Titheridge's model because data set is obtained with our own station. Both the IRI and Titheridge's model overestimate f oE especially in May to September months. Combing with past investigations, we suggest that overestimation of ionospheric parameters by IRI may be a common feature in East Asia. This result is very helpful for both the correction of IRI in East Asia and the development of Chinese Reference Ionosphere (CRI) model.

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Section: Methods Descriptionmentioning

confidence: 99%

Section: Methods Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An empirical model of ionospheric foE over Wuhan

et al. 2006

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“…Only starlight and scattered sunlight are important at heights between 98 and 120 km, with ion production occurring mainly in 100-112 km (Figures 2a and b). Full calculations using all four sources [Titheridge, 2000] where NInE = 3000 cm -3 at night. Other rocket observations (e.g., the review by Strobel [1974]) confirm that NO + and 02 + ions dominate the E region for day and night conditions.…”

Section: Changes With Heightmentioning

confidence: 99%

Production of the low‐latitude night E layer

Titheridge¹

2001

J. Geophys. Res.

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Abstract. A recent study of data from Arecibo concluded that the night E layer must consist primarily of metallic ions produced by meteors. Full model calculations show that this is not •ecessary. Known EUV sources (from starlight, scattered sunlight, and F region recombination) will produce an E region that agrees well with Arecibo results throughout the night. Direct rocket observations confirm that metallic ions are insignificant in the E region at all times. Model and data also agree on the absence of any appreciable changes with season or solar activity in the night values of NINE. The large solar cycle change in the IRI-95 model seems to come from an incorrect application of F region theory and should be deleted.

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“…Other sources are galactic cosmic rays (GCRs; ∼10 −1 cm −3 s −1 ), Scorpius XR-1 X-rays (∼10 −2 cm −3 s −1 ), and galactic X-rays (∼10 −3 cm −3 s −1 ). Theoretical calculation indicated that starlight (911-1026 Å; ∼10 0 cm −3 s −1 ) was also a cause of the ionization [Strobel et al, 1974;Titheridge, 2000]. In addition, particle precipitation from the inner radiation belt has been considered to play an important role in nighttime ionization.…”

Section: Introductionmentioning

confidence: 99%

Long-term variations in tweek reflection height in the D and lowerEregions of the ionosphere

2011

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[1] We investigated, for the first time, long-term variations in reflection heights of tweek atmospherics based on very low frequency (VLF) observations at Kagoshima, Japan. The results revealed the effects of the solar cycle on the nighttime lower ionosphere at low to middle latitudes. The tweek reflection heights on geomagnetically quiet days were analyzed every month over three solar cycles by using an automated spectral fitting procedure to estimate the cutoff frequency. The average and standard deviation of the reflection height were 95.9 km and ±3.1 km, respectively. Typical periods of time variation for the reflection height were 13.3, 3.2, 1.3, 1.0, 0.6, and 0.5 years. The variations in tweek reflection heights did not show simple anticorrelation with solar activity. The correlation coefficient between tweek reflection height and sunspot number was 0.03 throughout the three solar cycles. Hilbert-Huang transform analysis successfully indicated the presence of 0.5-1.5 year and ∼10 year variations as intrinsic mode functions (IMF). The decomposed IMF with the ∼10 year variation had a positive correlation with sunspot numbers and a negative correlation with galactic cosmic rays (GCRs). We hypothesize that these variations in tweek reflection heights could be caused by coupling of several ionization effects at the D and lower E regions, effects such as geocorona, GCRs, particle precipitation, and variations in neutral density in the lower thermosphere. Among these processes, the geocorona and particle precipitation could show negative correlation, while the GCRs and neutral density could show positive correlation with solar activities.Citation: Ohya, H., K. Shiokawa, and Y. Miyoshi (2011), Long-term variations in tweek reflection height in the D and lower E regions of the ionosphere,

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Modelling the peak of the ionospheric E-layer

Cited by 55 publications

References 32 publications

An empirical model of ionospheric foE over Wuhan

An empirical model of ionospheric foE over Wuhan

Production of the low‐latitude night E layer

Long-term variations in tweek reflection height in the D and lowerEregions of the ionosphere

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