Bibliography



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Found 4 entries in the Bibliography.


Showing entries from 1 through 4


2022

A Simulation Study on the Variation of Thermospheric O/N2 With Solar Activity

The ratio of number density of atomic oxygen (O) to that of molecular nitrogen (N2) in the thermosphere (O/N2) on the constant pressure surface, which has complex temporal and spatial characteristics, is widely regarded as an important parameter connecting the terrestrial thermosphere and daytime ionosphere. Previous studies demonstrated that the thermospheric O/N2 increases with increasing solar activity, and the changes in O/N2 with solar activity show significant difference between winter and summer hemispheres. However, the root causes, which are responsible for the solar activity variation of O/N2, are not fully understood. In this study, the contributions of various physical and chemical processes on the response of O/N2 to the solar radiation change were quantitatively investigated through a series of controlled simulations from the Thermosphere Ionosphere Electrodynamics General Circulation Model. The simulation results suggested that the chemical processes lead to the increase of thermospheric O/N2 over the globe with increasing solar activity. The increase of O/N2 with solar activity is dominated by the enrichment of O abundance and the loss of N2 abundance in the lower and upper thermosphere, respectively. Moreover, the simulation results suggested that the stronger hemispheric asymmetry is attributed to the stronger thermospheric circulation, which changes the vertical advection of O/N2 through both direct and indirect effects.

Li, Zhongli; Luan, Xiaoli; Lei, Jiuhou; Ren, Dexin;

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

YEAR: 2022     DOI: 10.1029/2022JA030305

circulation; O/N2; photochemistry; solar cycle; thermosphere

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) increase in the equinoctial asymmetry of\ h Fc\ with solar activity, (iii) presence of significant asymmetry in O/N2\ and TIEGCM simulations of normalized atomic oxygen mass density, between the two equinoxes.

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'Fc 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\textdegreeN, 80.2\textdegreeE) in the Indian longitude sector during equinoxes, winter, and summer seasons of 2002 to 2006 and the corresponding Thermosphere Ionosphere Mesosphere Energetics and Dynamics/GUVI (Global Ultra Violet Imager) O/N2 data are used for the study. The important findings that have emerged from this study are (i) the substantial increase of threshold height with magnetic activity for all the seasons and (ii) the modulation of h\textquoterightFc by neutral density changes, irrespective of season, solar, or magnetic activity.

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

2012

Research on Retrieving Thermospheric O/N2 from FUV Remote Sensing

Magnetic storms usually cause significant departures of thermospheric O and N2\ from their normal values. To study the effects on thermospheric neutral species caused by magnetic storms, a method to retrieve thermospheric O/N2\ based on the data obtained from global ultraviolet imager on board TIMED is presented. With the help of AURIC, the normalizations of observing angles and SZAs were preformed to the measurements and a relationship between 135.6/LBHs and O/N2\ was established. Finally, applying the proposed method to retrieve O/N2\ during a magnetic period(29, September\textemdash4, October, 2002), it was shown that magnetic storms could induce significant O/N2\ depletion, extending from the polar regions towards the equator.

Peng, S.; Tang, Y.; Wang, J.; Zheng, X.;

Published by: Spectroscopy and Spectral Analysis      Published on: 05/2012

YEAR: 2012     DOI: 10.3964/j.issn.1000-0593(2012)05-1296-05

AURIC; GUVI; Magnetic storm; O/N2



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