scholarly journals Spatial distribution of ionization in the equatorial and low-latitude ionosphere of the Indian sector and its effect on the pierce point altitude for GPS applications during low solar activity periods

2007 ◽  
Vol 112 (A5) ◽  
pp. n/a-n/a ◽  
Author(s):  
K. Niranjan ◽  
B. Srivani ◽  
S. Gopikrishna ◽  
P. V. S. Rama Rao
Keyword(s):  
Spatial Distribution ◽  
Solar Activity ◽  
Low Latitude ◽  
Low Latitude Ionosphere ◽  
Pierce Point ◽  
Indian Sector

scholarly journals The occurrence altitudes of middle atmospheric temperature inversions and mesopause over low-latitude Indian sector

2014 ◽  
Vol 32 (8) ◽  
pp. 967-974 ◽  
Author(s):  
M. Sivakandan ◽  
D. Kapasi ◽  
A. Taori
Keyword(s):  
Solar Activity ◽  
Atmospheric Temperature ◽  
Occurrence Rate ◽  
High Solar Activity ◽  
Night Time ◽  
Low Latitude ◽  
Small Peak ◽  
Occurrence Characteristics ◽  
Temperature Inversions ◽  
Indian Sector

Abstract. We study the occurrence characteristics of mesospheric inversion layers (MILs) in the 60–105 km altitude region over the low-latitude Indian sector. We note that lower inversions in the mesospheric temperatures occur in the 70–75 km altitude regions while the upper inversions occur in 90–95 km altitude regions. The mesopause altitude is mostly noted to be ~ 98 km with the night-time mesopause (particularly in the year 2002) showing a small peak in the mesopause occurrence at ~ 75 km altitude. We note higher occurrence rate of MILs during high solar activity year compared to low solar activity year. It is also observed that night time MILs show a systematic seasonal variability, with higher occurrence of single and double temperature inversions during equinoxes.

scholarly journals Response of the equatorial and low-latitude ionosphere in the Indian sector to the geomagnetic storms of January 2005

2009 ◽  
Vol 114 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
V. Sreeja ◽  
C. V. Devasia ◽  
Sudha Ravindran ◽  
Tarun Kumar Pant ◽  
R. Sridharan
Keyword(s):  
Geomagnetic Storms ◽  
Low Latitude ◽  
Low Latitude Ionosphere ◽  
Indian Sector

scholarly journals Wavenumber-4 structures observed in the low-latitude ionosphere during low and high solar activity periods using FORMOSAT/COSMIC observations

2018 ◽  
Vol 36 (2) ◽  
pp. 459-471 ◽  
Author(s):  
Amelia Naomi Onohara ◽  
Inez Staciarini Batista ◽  
Paulo Prado Batista
Keyword(s):  
Solar Activity ◽  
Peak Height ◽  
Diurnal Tide ◽  
High Solar Activity ◽  
Low Latitude ◽  
Peak Structure ◽  
F Region ◽  
E Region ◽  
Low Latitude Ionosphere ◽  
Layer Peak

Abstract. The main purpose of this study is to investigate the four-peak structure observed in the low-latitude equatorial ionosphere by the FORMOSAT/COSMIC satellites. Longitudinal distributions of NmF2 (the density of the F layer peak) and hmF2 (ionospheric F2-layer peak height) averages, obtained around September equinox periods from 2007 to 2015, were submitted to a bi-spectral Fourier analysis in order to obtain the amplitudes and phases of the main waves. The four-peak structure in the equatorial and low-latitude ionosphere was present in both low and high solar activity periods. This kind of structure possibly has tropospheric origins related to the tidal waves propagating from below that modulate the E-region dynamo, mainly the eastward non-migrating diurnal tide with wavenumber 3 (DE3, E for eastward). This wave when combined with the migrating diurnal tide (DW1, W for westward) presents a wavenumber-4 (wave-4) structure under a synoptic view. Electron densities observed during 2008 and 2013 September equinoxes revealed that the wave-4 structures became more prominent around or above the F-region altitude peak (∼  300–350 km). The four-peak structure remains up to higher ionosphere altitudes (∼  800 km). Spectral analysis showed DE3 and SPW4 (stationary planetary wave with wavenumber 4) signatures at these altitudes. We found that a combination of DE3 and SPW4 with migrating tides is able to reproduce the wave-4 pattern in most of the ionospheric parameters. For the first time a study using wave variations in ionospheric observations for different altitude intervals and solar cycle was done. The conclusion is that the wave-4 structure observed at high altitudes in ionosphere is related to effects of the E-region dynamo combined with transport effects in the F region.

Influence of tides on the ionospheric annual anomalies

2020 ◽  
Author(s):  
Zhipeng Ren ◽  
Weixing Wan ◽  
Jiangang Xiong ◽  
Libo Liu ◽  
Xing Li
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Relative Difference ◽  
Activity Level ◽  
Low Latitude ◽  
Ionospheric Electron Density ◽  
Solar Activity Level ◽  
Chinese Academy Of Sciences ◽  
Low Latitude Ionosphere ◽  
Academy Of Sciences

<p>Through respectively adding June tides and December tides at the low boundary of GCITEM-IGGCAS model (Global Coupled Ionosphere-Thermosphere-Electrodynamics Model, Institute of Geology and Geophysics, Chinese Academy of Sciences), we simulate the influence of tides on the annual anomalies of the ionospheric electron density. The tides’ influence on the annual anomalies of the ionospheric electron density varies with latitude, altitude and solar activity level. Compared with the density driven by December tides, the June tides mainly increases the lower ionospheric electron density, and mainly decreases the electron density at higher ionosphere. In the low-latitude ionosphere, tide drives an additional equatorial ionization anomaly structure (EIA) at higher ionosphere in the relative difference of electron density, which suggests that tide affect the equatorial vertical <strong>E×B</strong> plasma drifts. Although the lower ionospheric annual anomalies driven by tides mainly increases with the increase of solar activity, the annual anomalies at higher ionosphere mainly decreases with solar activity.</p><p></p>

VLF/LF (Very Low Frequency/Low Frequency) Reflection Properties of the Low Latitude Ionosphere

1988 ◽  
Author(s):  
Wayne I. Klemetti ◽  
Paul A. Kossey ◽  
John E. Rasmussen ◽  
Maria Sueli Da Silveira Macedo Moura
Keyword(s):  
Low Frequency ◽  
Low Latitude ◽  
Very Low Frequency ◽  
Low Latitude Ionosphere

Characterization of low latitude GPS-TEC during very low solar activity phase

2010 ◽  
Vol 72 (17) ◽  
pp. 1309-1317 ◽  
Author(s):  
Praveen Galav ◽  
N. Dashora ◽  
S. Sharma ◽  
R. Pandey
Keyword(s):  
Solar Activity ◽  
Low Latitude ◽  
Gps Tec ◽  
Activity Phase
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