GUVI Biblio





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Found 12 entries in the Bibliography.


Showing entries from 1 through 12


2022

The geoeffectiveness of TIE-GCM simulations of ionospheric critical frequency foF2 at the equatorial station of Thiruvananthapuram in the Indian sector

An extensive intercomparison of ionospheric foF2 observations and NCAR Thermosphere-Ionosphere ElectrodynamicsGeneral Circulation Model(TIE-GCM)simulations has been carried out for the dip equatorial location of Thiruvananthapuram. Ionosonde measurements for geomagnetically quiet days of 2002, 2006 and 2008, representing solar maximum, solar minimum and deep solar minimum conditions have been used for the analysis. In general TIE-GCM simulations reproduced the temporal and seasonal characteristics of foF2 over Thiruvananthap ...

Mridula, N.; Manju, G.; Sijikumar, S.; Pant, Tarun;

Published by: Advances in Space Research      Published on: may

YEAR: 2022     DOI: 10.1016/j.asr.2022.02.018

Comparison; foF2; TIE-GCM

The geoeffectiveness of TIE-GCM simulations of ionospheric critical frequency foF2 at the equatorial station of Thiruvananthapuram in the Indian sector

An extensive intercomparison of ionospheric foF2 observations and NCAR Thermosphere-Ionosphere ElectrodynamicsGeneral Circulation Model(TIE-GCM)simulations has been carried out for the dip equatorial location of Thiruvananthapuram. Ionosonde measurements for geomagnetically quiet days of 2002, 2006 and 2008, representing solar maximum, solar minimum and deep solar minimum conditions have been used for the analysis. In general TIE-GCM simulations reproduced the temporal and seasonal characteristics of foF2 over Thiruvananthap ...

Mridula, N.; Manju, G.; Sijikumar, S.; Pant, Tarun;

Published by: Advances in Space Research      Published on: may

YEAR: 2022     DOI: 10.1016/j.asr.2022.02.018

Comparison; foF2; TIE-GCM

Quantification of the role of gravity wave induced TIDs in modulating ESF day to day variability during geomagnetically disturbed periods

The control of magnetic disturbance induced seed perturbations on the daily variation in night-time ionization irregularity occurrence is studied using ionosonde data and TIMED/GUVI neutral density data at the magnetic equatorial region, Trivandrum. The study reveals that there is a requisite threshold seed amplitude for ESF to occur at a particular altitude and this requisite seed increases as the altitude decreases. This dependence of requisite seed perturbation on altitude for multiple years, which incorporates the electr ...

Sruthi, T.; Manju, G.;

Published by: Advances in Space Research      Published on: mar

YEAR: 2022     DOI: 10.1016/j.asr.2021.11.038

Equatorial ionosphere; Equatorial Spread F; Geomagnetically disturbed period; neutral density

2018

First Time Estimation of Thermospheric Neutral Density Profiles From Seed Perturbations of ESF Triggering: A Novel Evidence for Ionosphere Thermosphere Coupling

The present study reveals the coupling between the neutral densities, derived from the Global Ultraviolet Imager satellite and the requisite gravity wave seed perturbations for equatorial spread F occurrence (Manju et al., 2016, https://doi.org/10.1016/j.asr.2015.12.019), derived from the ionosonde data at Trivandrum (8.5\textdegreeN, 77\textdegreeE). Further, the relation between the above two parameters is found to have solar flux depe ...

Manju, G.; Aswathy, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2018

YEAR: 2018     DOI: 10.1029/2018JA025967

Solar activity variations of equatorial spread F occurrence and sustenance during different seasons over Indian longitudes: Empirical model and causative mechanisms

A comprehensive analysis using nearly two decades of ionosonde data is carried out on the seasonal and solar cycle variations of Equatorial Spread F (ESF) irregularities over magnetic equatorial location Trivandrum (8.5\textdegreeN, 77\textdegreeE). The corresponding Rayleigh Taylor (RT) instability growth rates (γ) are also estimated. A seasonal pattern of ESF occurrence and the corresponding γ is established for low solar (LSA), medium solar (MSA) and high solar (HSA) activity p ...

Haridas, M.K.; Manju, G.; Arunamani, T.;

Published by: Advances in Space Research      Published on: 05/2018

YEAR: 2018     DOI: 10.1016/j.asr.2018.02.040

First time estimation of thermospheric neutral density profiles from seed perturbations of ESF triggering: A novel evidence for ionosphere thermosphere coupling

Manju, G; Aswathy, RP;

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

YEAR: 2018     DOI:

2015

On the equinoctial asymmetry in the threshold height for the occurrence of equatorial spread F

In the present study, the threshold height (h Fc) for ESF occurrence irrespective of the polarity of the meridional winds during vernal and autumnal equinoxes is investigated using a large database spread over 1993\textendash2008. The characteristics of the thermosphere during the two equinoxes have also been examined using TIMED/GUVI O/N2 data. The major aspects that have emerged are (i) presence of significant equinoctial asymmetry inh Fc\ for the years examined, (ii) increas ...

Manju, G.; Haridas, M.K.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 03/2015

YEAR: 2015     DOI: 10.1016/j.jastp.2015.01.008

Threshold height; O/N2; Equinoctial asymmetry; Solar flux

2013

First observational evidence of the modulation of the threshold height h\textquoterightF c for the occurrence of equatorial spread F by neutral composition changes

[1]\ In the present study, the seasonal and solar activity variations of the threshold height for equatorial spread F occurrence irrespective of the polarity of the meridional winds during magnetically disturbed period are presented for the first time. The modulation of the seasonal pattern of the threshold height by the seasonal mean O/N2 values is also examined. The Ionosonde data of magnetic equatorial location Trivandrum (8.5\textdegreeN, 76.5\textdegreeE) and low latitude station SHAR (13.7\t ...

Haridas, M.; Manju, G.; Pant, Tarun;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/jgra.50331

Equatorial Spread F; O/N2; solar activity; Threshold height

Ionospheric response to a geomagnetic storm during November 8\textendash10, 2004

This paper investigates the response of the equatorial, and near equatorial, ionosphere to geomagnetic disturbances during the period November 8-10, 2004. Ionosonde data from Trivandrum (8.5\textdegreeN 77\textdegreeE and dip 0.5\textdegreeN) and SHAR (13.5\textdegreeN, 80.2\textdegreeE, dip \~5.5\textdegreeN), magnetic field data from Tirunelveli (8.7\textdegreeN, 76.9\textdegreeE, dip latitude 0.5\textdegreeS) and Alibag (18.64\textdegreeN, 72.87\textdegreeE), and GUVI O/N2 data in the Indian longitude sector ...

Simi, K.; Manju, G.; Haridas, M.; Nayar, S.; Pant, Tarun; Alex, S.;

Published by: Earth, Planets and Space      Published on: 05/2013

YEAR: 2013     DOI: 10.5047/eps.2012.09.005

Equatorial Electrojet; Equatorial ionization anomaly; geomagnetic storm; O/N2 ratio

Ionospheric response to a geomagnetic storm during November 8-10, 2004

Simi, KG; Manju, G; Haridas, MK; , Nayar; Pant, Tarun; Alex, S;

Published by: Earth, Planets and Space      Published on:

YEAR: 2013     DOI:

First observational evidence of the modulation of the threshold height h Fc for the occurrence of equatorial spread F by neutral composition changes

Haridas, MK; Manju, G; Pant, Tarun;

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

YEAR: 2013     DOI:

IONOSPHERIC RESPONSE TO A GEOMAGNETIC STORM DURING NOVEMBER 08-10, 2004

Simi, KG; Manju, G; Haridas, MK; Nayar, Prabhakaran; Pant, Tarun; Alex, S;

Published by:       Published on:

YEAR:     DOI:



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