Emerging pattern of global change in the upper atmosphere and ionosphere

Laštovička, Jan; Akmaev, R. A.; Beig, Gufran; Bremer, J.; Emmert, J. T.; Jacobi, Ch.; Jarvis, M. J.; Nedoluha, Gerald E.; Portnyagin, Yu. I.; Ulich, Thomas

doi:10.5194/angeo-26-1255-2008

Cited by 111 publications

(102 citation statements)

References 79 publications

(130 reference statements)

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“…The whole period is separated into two sub-periods (1957-1989 and 1990-2002). The sub-periods were chosen in accordance with the change in trends of yearly averaged winds in the mesopause region (Laštovička et al, 2008). The selected latitude of 52.5 • N is separated into four sectors (0-90 • E -European sector, 90-180 • E -Asian sector, 180-300 • W -Pacific-American sector, and 300-360 • E -Atlantic sector).…”

Section: Methodsmentioning

confidence: 99%

Differences in mid-latitude stratospheric winds between reanalysis data and versus radiosonde observations at Prague

2014

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Section: Methodsmentioning

confidence: 99%

Differences in mid-latitude stratospheric winds between reanalysis data and versus radiosonde observations at Prague

2014

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“…They have shown that even under the double CO 2 increase scenario (which we are very far from) the predicted ionospheric effects should be small. But their results have stimulated researchers to relate the observed ionospheric long-term trends to the thermosphere greenhouse cooling (Ulich & Turunen, 1997;Sharma et al, 1999;Alfonsi et al, 2001Alfonsi et al, , 2002La stovička et al, 2008;Qian et al, 2008Qian et al, , 2009La stovička et al, 2012;Danilov & Konstantinova, 2013;Mielich & Bremer, 2013;Konstantinova & Danilov, 2015;Roininen et al, 2015). The mechanisms of the thermospheric and ionospheric trends may be different and serious contradictions with the CO 2 hypothesis confirm this (Perrone & Mikhailov, 2016).…”

Section: Introductionmentioning

confidence: 99%

Long-term variations of the upper atmosphere parameters on Rome ionosonde observations and their interpretation

Perrone

Mikhailov

Cesaroni

et al. 2017

J. Space Weather Space Clim.

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-A recently proposed self-consistent approach to the analysis of thermospheric and ionospheric long-term trends has been applied to Rome ionosonde summer noontime observations for the period. This approach includes: (i) a method to extract ionospheric parameter long-term variations; (ii) a method to retrieve from observed f o F 1 neutral composition (O, O 2 , N 2 ), exospheric temperature, Tex and the total solar EUV flux with l < 1050 Å; and (iii) a combined analysis of the ionospheric and thermospheric parameter long-term variations using the theory of ionospheric F-layer formation. Atomic oxygen, [O] period which is mainly due to atomic oxygen decrease after ∼1990. A linear trend in (dh m F 2 ) 11y estimated over the period is very small and insignificant reflecting the absence of any significant trend in neutral temperature. The retrieved neutral gas density, r atomic oxygen, [O] and exospheric temperature, Tex long-term variations are controlled by solar and geomagnetic activity, i.e. they have a natural origin. The residual trends estimated over the period of ∼5 solar cycles are very small (<0.5% per decade) and statistically.

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“…The cycles of the variations in electron density are in agreement with each wave cycle. However, clear long-term variations in atmospheric wave activity have not been obtained [e.g., Gavrilov et al, 2002;Jacobi et al, 2006;Laštovička et al, 2008]. Thus, it is not likely that atmospheric waves cause the longterm variations in tweek reflection height.…”

Section: Comparison With Empirical Modelsmentioning

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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Emerging pattern of global change in the upper atmosphere and ionosphere

Cited by 111 publications

References 79 publications

Differences in mid-latitude stratospheric winds between reanalysis data and versus radiosonde observations at Prague

Differences in mid-latitude stratospheric winds between reanalysis data and versus radiosonde observations at Prague

Long-term variations of the upper atmosphere parameters on Rome ionosonde observations and their interpretation

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

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