scholarly journals An investigation of the ionospheric F-region near the EIA crest in India using OI 777.4 and 630.0 nm nightglow observations

2018 ◽  
Author(s):  
Navin Parihar ◽  
Sandro M. Radicella ◽  
Bruno Nava ◽  
Yenca Olivia Migoya Orue ◽  
Prabhakar Tiwari ◽  
...  
Keyword(s):  
Electron Density ◽  
Gravity Waves ◽  
Satellite Mission ◽  
Low Latitude ◽  
Density Maximum ◽  
Density Profiles ◽  
F Region ◽  
Equatorial Ionization Anomaly ◽  
Low Latitude Ionosphere ◽  
Electron Density Profiles

Abstract. Simultaneous observations of OI 777.4 nm and OI 630.0 nm nightglow emissions were carried at a low latitude station, Allahabad (25.5º N, 81.9º E, geomag. lat. ~16.30º N), located near the crest of Appleton anomaly in India during September–December 2009. This study attempts to examine the behaviour of the F region of ionosphere using airglow derived parameters. Using an empirical approach put forward by Makela et al. (2001), firstly, we propose a novel technique to calibrate OI 777.4 and 630.0 nm emission intensities using Constellation Observing System for Meteorology, Ionosphere, and Climate/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3) electron density profiles. Next, electron density maximum (Nm) and its height (hmF2) of the F-layer have been derived from the information of two calibrated intensities. Nightglow derived Nm and hmF2 were in reasonable agreement with few measurements reported earlier. Nm and hmF2 were used to study the behaviour of the F-region over Allahabad on the limited number of nights. Nocturnal variation of Nm showed the signatures of the retreat of equatorial ionization anomaly (EIA) and mid-night temperature maximum (MTM) phenomenon that are usually observed in the equatorial and low-latitude ionosphere. Signatures of gravity waves having period in the range of 0.7–3.0 h were also seen in Nm and hmF2 variations. Sample Nm and hmF2 maps have also been generated to show the usefulness of this technique in studying the ionospheric processes.

scholarly journals An investigation of the ionospheric F region near the EIA crest in India using OI 777.4 and 630.0 nm nightglow observations

2018 ◽  
Vol 36 (3) ◽  
pp. 809-823 ◽  
Author(s):  
Navin Parihar ◽  
Sandro Maria Radicella ◽  
Bruno Nava ◽  
Yenca Olivia Migoya-Orue ◽  
Prabhakar Tiwari ◽  
...  
Keyword(s):  
Electron Density ◽  
Gravity Waves ◽  
Satellite Mission ◽  
Low Latitude ◽  
Density Maximum ◽  
Density Profiles ◽  
F Region ◽  
Equatorial Ionization Anomaly ◽  
Low Latitude Ionosphere ◽  
Electron Density Profiles

Abstract. Simultaneous observations of OI 777.4 and OI 630.0 nm nightglow emissions were carried at a low-latitude station, Allahabad (25.5° N, 81.9° E; geomag. lat.  ∼  16.30° N), located near the crest of the Appleton anomaly in India during September–December 2009. This report attempts to study the F region of ionosphere using airglow-derived parameters. Using an empirical approach put forward by Makela et al. (2001), firstly, we propose a novel technique to calibrate OI 777.4 and 630.0 nm emission intensities using Constellation Observing System for Meteorology, Ionosphere, and Climate/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3) electron density profiles. Next, the electron density maximum (Nm) and its height (hmF2) of the F layer have been derived from the information of two calibrated intensities. Nocturnal variation of Nm showed the signatures of the retreat of the equatorial ionization anomaly (EIA) and the midnight temperature maximum (MTM) phenomenon that are usually observed in the equatorial and low-latitude ionosphere. Signatures of gravity waves with time periods in the range of 0.7–3.0 h were also seen in Nm and hmF2 variations. Sample Nm and hmF2 maps have also been generated to show the usefulness of this technique in studying ionospheric processes.

scholarly journals F-region electron density and <i>T<sub>e</sub> / T<sub>i</sub></i> measurements using incoherent scatter power data collected at ALTAIR

2006 ◽  
Vol 24 (5) ◽  
pp. 1333-1342 ◽  
Author(s):  
M. Milla ◽  
E. Kudeki
Keyword(s):  
Electron Density ◽  
Topside Ionosphere ◽  
Low Latitude ◽  
Aspect Angle ◽  
Incoherent Scatter ◽  
F Region ◽  
Regularized Inversion ◽  
The Pacific ◽  
Resolution Electron ◽  
Low Latitude Ionosphere

Abstract. The ALTAIR UHF radar was used in an incoherent scatter experiment to observe the low-latitude ionosphere during the Equis 2 rocket campaign. The measurements provided the first high-resolution electron density maps of the low-latitude D- and E-region in the Pacific sector and also extended into the F-region and topside ionosphere. Although the sampling frequency was well below the Nyquist frequency of F-region returns, we were able to estimate Te / Ti ratio and infer unbiased electron density estimates using a regularized inversion technique described here. The technique exploits magnetic aspect angle dependence of ISR cross-section for Te>Ti.

scholarly journals Comparative study of electron density from incoherent scatter measurements at Arecibo with the IRI-95 model during solar maximum

2000 ◽  
Vol 18 (12) ◽  
pp. 1630-1634 ◽  
Author(s):  
N. K. Sethi ◽  
V. K. Pandey
Keyword(s):  
Electron Density ◽  
Solar Maximum ◽  
Iri Model ◽  
Bottom Part ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
F Region ◽  
Electron Density Profiles ◽  
Thickness Parameter ◽  
Modelling And Forecasting

Abstract. Arecibo (18.4 N, 66.7 W) incoherent scatter (IS) observations of electron density N(h) are compared with the International Reference Ionosphere (IRI-95) during midday (10–14 h), for summer, winter and equinox, at solar maximum (1981). The N(h) profiles below the F2 peak, are normalized to the peak density NmF2 of the F region and are then compared with the IRI-95 model using both the standard B0 (old option) and the Gulyaeva-B0 thickness (new option). The thickness parameter B0 is obtained from the observed electron density profiles and compared with those obtained from the IRI-95 using both the options. Our studies indicate that during summer and equinox, in general, the values of electron densities at all the heights given by the IRI model (new option), are generally larger than those obtained from IS measurements. However, during winter, the agreement between the IRI and the observed values is reasonably good in the bottom part of the F2 layer but IRI underestimates electron density at F1 layer heights. The IRI profiles obtained with the old option gives much better results than those generated with the new option. Compared to the observations, the IRI profiles are found to be much thicker using Gulyaeva-B0 option than using standard B0.Key words: Ionosphere (modelling and forecasting)

scholarly journals Comparison of ionospheric radio occultation CHAMP data with IRI 2001

2005 ◽  
Vol 2 ◽  
pp. 275-279 ◽  
Author(s):  
N. Jakowski ◽  
K. Tsybulya
Keyword(s):  
Electron Density ◽  
Radio Occultation ◽  
Satellite Orbit ◽  
High Solar Activity ◽  
Satellite Mission ◽  
Density Profiles ◽  
Champ Satellite ◽  
Ionospheric Models ◽  
Routine Basis ◽  
Electron Density Profiles

Abstract. GPS radio occultation measurements on board low Earth orbiting satellites can provide vertical electron density profiles of the ionosphere from satellite orbit heights down to the bottomside. Ionospheric radio occultation (IRO) measurements carried out onboard the German CHAMP satellite mission since 11 April 2001 were used to derive vertical electron density profiles (EDP’s) on a routine basis. About 150 vertical electron density profiles may be retrieved per day thus providing a huge data basis for testing and developing ionospheric models. Although the validation of the EDP retrievals is not yet completed, the paper addresses a systematic comparison of about 78 000 electron density profiles derived from CHAMP IRO data with the International Reference Ionosphere (IRI 2001). The results are discussed for quite different geophysical conditions, e.g. as a function of latitude, local time and geomagnetic activity. The comparison of IRO data with corresponding IRI data indicates that IRI generally overestimates the upper part of the ionosphere whereas it underestimates the lower part of the ionosphere under high solar activity conditions. In a first order correction this systematic deviation could be compensated by introducing a height dependence correction factor in IRI profiling.

THE CONDITION OF THE UPPER ATMOSPHERE BASED ON THE ELECTRON DENSITY PROFILES OF THE F REGION

1966 ◽  
Vol 44 (1) ◽  
pp. 175-205 ◽  
Author(s):  
Nobuo Matuura
Keyword(s):  
Electron Density ◽  
Molecular Nitrogen ◽  
Dissociative Recombination ◽  
Atmospheric Parameters ◽  
Density Profiles ◽  
Density Distributions ◽  
F Region ◽  
Recombination Processes ◽  
Ion Production ◽  
Electron Density Profiles

The upper atmospheric parameters that control the daytime electron density distributions in the F1 region have been determined with the use of N(h) profiles. The analysis is based on the photochemical equilibrium state in which ion production is given by the ionization of molecular nitrogen and/or molecular oxygen as well as of atomic oxygen, and ionization loss is controlled by charge transfer and dissociative recombination processes. The variations of the upper atmospheric parameters with season, solar activity, and magnetic disturbances have been obtained, and their relations to the behavior of the F1 and F2 layers have been examined.

scholarly journals Vertical electron density and topside effective scale height (<I>H</I><sub>T</sub>) variations over the Indian equatorial and low latitude stations

2011 ◽  
Vol 29 (10) ◽  
pp. 1861-1872 ◽  
Author(s):  
K. Venkatesh ◽  
P. V. S. Rama Rao ◽  
P. L. Saranya ◽  
D. S. V. V. D. Prasad ◽  
K. Niranjan
Keyword(s):  
Diurnal Variation ◽  
Electron Density ◽  
Scale Height ◽  
Electron Content ◽  
Iri Model ◽  
Night Time ◽  
Low Latitude ◽  
Density Profiles ◽  
Gps Tec ◽  
Electron Density Profiles

Abstract. Understanding the vertical electron density profile, which is the altitudinal variation of ionospheric electron density distribution is an important aspect for the ionospheric investigations. In this paper, the bottom-side electron density profiles derived from ground based ionosonde data and the ROCSAT-1 in-situ electron density data were used to determine the estimates of the topside electron density profiles using α-Chapman function over an equatorial station Trivandrum (8.47° N, 76.91° E) and a low latitude station Waltair (17.7° N, 83.3° E) in the Indian region. The reconstructed electron density profiles are compared with IRI (2007) model derived vertical electron density profiles which resulted in significant deviations between the two different profiles. Both the reconstructed electron density profiles and the IRI model derived profiles are integrated independently to derive the Total Electron Content (TEC) values which are compared with GPS derived TEC values. TEC values derived from the reconstructed electron density profiles give better estimates with the GPS-TEC compared to those of IRI model derived TEC values. Compared to the GPS-TEC, the IRI model is underestimating the TEC values during day-time and is overestimating during night-time at both the stations. The percentage deviations of IRI derived TEC from GPS-TEC are larger compared to those between reconstructed profile derived TEC and GPS-TEC. F2-layer peak electron density, peak height and electron density at ROCSAT altitudes (≈600 km) are used to derive the effective scale heights (HT) of the topside ionosphere during the period from July 2003 to June 2004. The diurnal and seasonal variations of HT and E×B drift velocities are presented in this paper. The diurnal variation of the effective scale height (HT) shows peak values around noon hours with higher values during day-time and lower values during night-time both at Trivandrum and Waltair. The E×B drift velocities at both the places also have shown a clear diurnal variation with a negative peak around 04:00 LT and maximum during day-time hours. The higher and lower values of HT seem to be associated with positive and negative phases of the E×B drift velocities, respectively.

scholarly journals Plasma line observations from the EISCAT Svalbard Radar during the International Polar Year

2017 ◽  
Vol 35 (5) ◽  
pp. 1143-1149
Author(s):  
Nickolay Ivchenko ◽  
Nicola M. Schlatter ◽  
Hanna Dahlgren ◽  
Yasunobu Ogawa ◽  
Yuka Sato ◽  
...  
Keyword(s):  
Electron Density ◽  
Time Of Day ◽  
Fast Method ◽  
International Polar Year ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
F Region ◽  
Plasma Line ◽  
International Polar ◽  
Electron Density Profiles

Abstract. Photo-electrons and secondary electrons from particle precipitation enhance the incoherent scatter plasma line to levels sufficient for detection. When detectable the plasma line gives accurate measure of the electron density and can potentially be used to constrain incoherent scatter estimates of electron temperature. We investigate the statistical occurrence of plasma line enhancements with data from the high-latitude EISCAT Svalbard Radar obtained during the International Polar Year (IPY, 2007–2008). A computationally fast method was implemented to recover the range-frequency dependence of the plasma line. Plasma line backscatter strength strongly depends on time of day, season, altitude, and geomagnetic activity, and the backscatter is detectable in 22.6 % of the total measurements during the IPY. As expected, maximum detection is achieved when photo-electrons due to the Sun's EUV radiation are present. During summer daytime hours the occurrence of detectable plasma lines at altitudes below the F-region peak is up to 90 %. During wintertime the occurrence is a few percent. Electron density profiles recovered from the plasma line show great detail of density variations in height and time. For example, effects of inertial gravity waves on the electron density are observed.

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