Spatiotemporal Variations of Quiet Time Equatorial Ionosphere Longitudinal Structure Under Low Solar Activity

2021 ◽  
Vol 126 (2) ◽  
Author(s):  
Weijun Hou ◽  
Buyun Xu ◽  
Hongxia Wang ◽  
Yihong Li ◽  
Xihai Li ◽  
...  
Keyword(s):  
Solar Activity ◽  
Equatorial Ionosphere ◽  
Spatiotemporal Variations ◽  
Quiet Time ◽  
Longitudinal Structure

Temporal modulation of the four-peaked longitudinal structure of the equatorial ionosphere by the 2 day planetary wave

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Guiping Liu ◽  
Thomas J. Immel ◽  
Scott L. England ◽  
Karanam K. Kumar ◽  
Geetha Ramkumar
Keyword(s):  
Planetary Wave ◽  
Equatorial Ionosphere ◽  
Temporal Modulation ◽  
Longitudinal Structure

scholarly journals Stormtime dynamics of the global thermosphere and equatorial ionosphere

2009 ◽  
Vol 27 (5) ◽  
pp. 2035-2044 ◽  
Author(s):  
W. J. Burke ◽  
C. Y. Huang ◽  
R. D. Sharma
Keyword(s):  
Equatorial Ionosphere ◽  
Magnetic Storms ◽  
Main Phase ◽  
New Method ◽  
Sufficient Time ◽  
Quiet Time ◽  
Early Recovery ◽  
Plasma Bubbles ◽  
Equatorial Plasma Bubbles ◽  
Phase Activity

Abstract. During magnetic storms the development of equatorial plasma bubbles (EPBs) and distributions of thermospheric densities are strongly influenced by the histories of imposed magnetospheric electric (εM) fields. Periods of intense EPB activity driven by penetration εM fields in the main phase are followed by their worldwide absence during recovery. A new method is applied to estimate global thermospheric energy (Eth) budgets from orbit-averaged densities measured by accelerometers on polar-orbiting satellites. During the main phase of storms Eth increases as long as the stormtime εM operates, then exponentially decays toward quiet-time values during early recovery. Some fraction of the energy deposited at high magnetic latitudes during the main phase propagates into the subauroral ionosphere-thermosphere where it affects chemical and azimuthal-wind dynamics well into recovery. We suggest a scenario wherein fossils of main phase activity inhibit full restoration of quiet-time dayside dynamos and pre-reversal enhancements of upward plasma drifts near dusk denying bottomside irregularities sufficient time to grow into EPBs.

scholarly journals Temporal modulations of the longitudinal structure inF2peak height in the equatorial ionosphere as observed by COSMIC

2010 ◽  
Vol 115 (A4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Guiping Liu ◽  
Thomas J. Immel ◽  
Scott L. England ◽  
Karanam K. Kumar ◽  
Geetha Ramkumar
Keyword(s):  
Equatorial Ionosphere ◽  
Longitudinal Structure

Validating IRI-2016 for quiet-time F2-region peak electron density height (hmF2) at different latitudes during moderate solar activity

2021 ◽  
Author(s):  
J.O. Adeniyi ◽  
B.O. Adebesin ◽  
S.O. Ikubanni ◽  
S.J. Adebiyi ◽  
B.J. Adekoya ◽  
...  
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Quiet Time

Seasonal variation and solar activity dependence of the quiet-time ionospheric trough

2014 ◽  
Vol 119 (8) ◽  
pp. 6774-6783 ◽  
Author(s):  
T. Ishida ◽  
Y. Ogawa ◽  
A. Kadokura ◽  
Y. Hiraki ◽  
I. Häggström
Keyword(s):  
Seasonal Variation ◽  
Solar Activity ◽  
Quiet Time ◽  
Activity Dependence

scholarly journals <i>Letter to the Editor</i>: Post-midnight onset of spread-F at Kodaikanal during the June solstice of solar minimum

1999 ◽  
Vol 17 (8) ◽  
pp. 1111-1115 ◽  
Author(s):  
J. H. Sastri
Keyword(s):  
Solar Activity ◽  
Solar Minimum ◽  
Equatorial Ionosphere ◽  
Instability Mechanism ◽  
Layer Height ◽  
Northern Summer ◽  
June Solstice ◽  
Spread F ◽  
Rayleigh Taylor Instability ◽  
Distinct Increase

Abstract. At dip equatorial stations in the Indian zone, spread-F conditions are known to develop preferentially around midnight during the June solstice (northern summer) months of low solar activity, in association with a distinct increase in F layer height. It is currently held that this onset of spread-F far away from the sunset terminator is due to the generalised Rayleigh-Taylor instability mechanism, with the gravitational and cross-field instability factors (and hence F layer height) playing important roles. We have studied the quarter-hourly ionograms of Kodaikanal (10.2°N; 77.5°E; dip 4°N) for the northern summer months (May-August) of 1994 and 1995 to ascertain the ambient ionospheric conditions against which the post-midnight onset of spread-F takes place. A data sample of 38 nights with midnight onset of spread-F and 34 nights without spread-F is used for the purpose. It is found that a conspicious increase in F layer height beginning around 2100 LT occurs on nights with spread-F as well as without spread-F. This feature is seen in the nocturnal pattern of F layer height on many individual nights as well as of average F layer height for the two categories of nights. The result strongly suggests that the F layer height does not play a pivotal role in the midnight onset of spread-F during the June solstice of solar minimum. The implications of this finding are discussed.Key words. Ionosphere (equatorial ionosphere; ionospheric irregularities)

scholarly journals Climatology Characteristics of Ionospheric Irregularities Described with GNSS ROTI

2020 ◽  
Vol 12 (16) ◽  
pp. 2634 ◽  
Author(s):  
Kacper Kotulak ◽  
Irina Zakharenkova ◽  
Andrzej Krankowski ◽  
Iurii Cherniak ◽  
Ningbo Wang ◽  
...  
Keyword(s):  
Solar Activity ◽  
Geomagnetic Activity ◽  
Geomagnetic Storms ◽  
Auroral Oval ◽  
Ionospheric Irregularities ◽  
Moderate Intensity ◽  
Navigation Systems ◽  
Quiet Time ◽  
Magnetic Latitude

At equatorial and high latitudes, the intense ionospheric irregularities and plasma density gradients can seriously affect the performances of radio communication and satellite-based navigation systems; that represents a challenging topic for the scientific and engineering communities and operational use of communication and navigation services. The GNSS-based ROTI (rate of TEC index) is one of the most widely used indices to monitor the occurrence and intensity of ionospheric irregularities. In this paper, we examined the long-term performance of the ROTI in terms of finding the climatological characteristics of TEC fluctuations. We considered the different scale temporal signatures and checked the general sensitivity to the solar and geomagnetic activity. We retrieved and analyzed long-term time-series of ROTI values for two chains of GNSS stations located in European and North-American regions. This analysis covers three full years of the 24th solar cycle, which represent different levels of solar activity and include periods of intense geomagnetic storms. The ionospheric irregularities’ geographical distribution, as derived from ROTI, shows a reasonable consistency to be found within the poleward/equatorward boundaries of the auroral oval specified by empirical models. During magnetic midnight and quiet-time conditions, the equatorward boundary of the ROTI-derived ionospheric irregularity zone was observed at 65–70° of north magnetic latitude, while for local noon conditions this boundary was more poleward at 75–85 magnetic latitude. The ionospheric irregularities of low-to-moderate intensity were found to occur within the auroral oval at all levels of geomagnetic activity and seasons. At moderate and high levels of solar activity, the intensities of ionospheric irregularities are larger during local winter conditions than for the local summer and polar day conditions. We found that ROTI displays a selective latitudinal sensitivity to the auroral electrojet activity—the strongest dependence (correlation R > 0.6–0.8) was observed within a narrow latitudinal range of 55–70°N magnetic latitude, which corresponded to a band of the largest ROTI values within the auroral oval zone expanded equatorward during geomagnetic disturbances.

Sign in / Sign up

Export Citation Format

Share Document