Bibliography



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Found 2 entries in the Bibliography.


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2022

Climatology of global, hemispheric and regional electron content variations during the solar cycles 23 and 24

We present the results of study on the variations of ionospheric total electron content (TEC) by using global, hemispheric, and regional electron contents computed from the global ionospheric maps (GIMs) for the period from 1999 to 2020. For a low and moderate solar activity, the global and regional electron contents vary linearly with solar 10.7 cm radio flux and EUV flux. While a saturation effect in the electron content verses EUV and F10.7 is found during the high solar activity periods at all regions, the maximum effect is observed at low-latitudes followed by high and mid-latitudes region. The extent of saturation effect is more pronounced for F10.7 as compared to EUV. A wavelet transform is applied to global and hemispheric electron contents to examine the relative strength of different variations. The semi-annual variations dominate in the northern hemisphere, whereas annual variations dominate in the southern counterpart. The amplitude of annual variations in southern hemisphere is found to be higher than northern counterpart at all latitudes. This asymmetry in the amplitude of annual variation is maximum at low-latitudes, followed by mid and high-latitudes, respectively. The semi-annual variations are in-phase in both hemisphere and follow the solar cycle. The northern hemisphere depicts relatively large amplitude of semi-annual variations and exhibit the maximum effect at high-latitudes.

Younas, Waqar; Amory-Mazaudier, C.; Khan, Majid; Amaechi, Paul;

Published by: Advances in Space Research      Published on: jul

YEAR: 2022     DOI: 10.1016/j.asr.2022.07.029

annual variation; global electron content; Ionosphere; semi-annual variation; total electron content

Seasonal Variation of Thermospheric Composition Observed by NASA GOLD

We examine characteristics of the seasonal variation of thermospheric composition using column number density ratio ∑O/N2 observed by the NASA Global Observations of Limb and Disk (GOLD) mission from low-mid to mid-high latitudes. We also use ∑O/N2 derived from the Global Ultraviolet Imager (GUVI) limb measurements onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite and estimated by the NRLMSISE-00 empirical model to aid our investigation. We found that the ∑O/N2 seasonal variation is hemispherically asymmetric: in the southern hemisphere, it exhibits the well-known annual and semiannual pattern, with highs near the equinoxes, and primary and secondary lows near the solstices. In the northern hemisphere, it is dominated by an annual variation, with a minor semiannual component with the highs shifting toward the wintertime. We also found that the durations of the December and June solstice seasons in terms of ∑O/N2 are highly variable with longitude. Our hypothesis is that ion-neutral collisional heating in the equatorial ionization anomaly region, ion drag, and auroral Joule heating play substantial roles in this longitudinal dependency. Finally, the rate of change in ∑O/N2 from one solstice season to the other is dependent on latitude, with more dramatic changes at higher latitudes.

Qian, Liying; Gan, Quan; Wang, Wenbin; Cai, Xuguang; Eastes, Richard; Yue, Jia;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2022     DOI: 10.1029/2022JA030496

annual variation; GOLD observation; MSIS; seasonal variation; semiannual variation; thermosphere composition



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