TEC variations during low solar activity period (2005–2007) near the Equatorial Ionospheric Anomaly Crest region in India

Bagiya, Mala S.; Joshi, H. P.; Iyer, K. N.; Aggarwal, Malini; Ravindran, Sudha; Pathan, B. M.

doi:10.5194/angeo-27-1047-2009

Cited by 221 publications

(145 citation statements)

References 34 publications

(25 reference statements)

Supporting

Mentioning

126

Contrasting

Order By: Relevance

“…This gives rise to a positive ionospheric storm (e.g., Buonsanto, 1999) whereby the TEC is also increased. As is expected, local uplifting of plasma and its re-distribution due to the eastward PPEF would have a certain time constant and has been observed by others also (Tsurtani et al, 2004;Bagiya et al, 2009). Therefore the first peak in VTEC occurs nearly after 1 h 45 min of the southward turning of the IMF B z .…”

Section: Longitudinal Variation Of Vtecmentioning

confidence: 72%

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Sharma¹,

Galav²,

Dashora

et al. 2011

Ann. Geophys.

View full text Add to dashboard Cite

Abstract.Response of low latitude ionosphere to the geomagnetic storm of 15 May 2005 has been studied using total electron content (TEC) data, obtained from three GPS stations namely, Yibal, Udaipur and Kunming situated near the northern crest of equatorial ionization anomaly at different longitudes. Solar wind parameters, north-south component of the interplanetary magnetic field (IMF B z ) and AE index data have been used to infer the strength of the geomagnetic storm. A large value of eastward interplanetary electric field at 06:15 UT, during the time of maximum southward IMF B z has been used to infer the transmission of an eastward prompt penetration electric field (PPEF) which resulted in a peak in TEC at 07:45 UT due to the local uplift of plasma in the low latitudes near the anomaly crest over a wide range of longitudes. Wave-like modulations superposed over the second enhancement in TEC between 09:15 UT to 10:30 UT have been observed at all the three stations. The second enhancement in TEC along with the modulations of up to 5 TECU have been attributed to the combined effect of super plasma fountain and traveling atmospheric disturbances (TAD). Observed large enhancements in TEC are a cause of concern for satellite based navigation and ground positioning. Increased [O/N 2 ] ratio between 09:15 UT to 10:15 UT when modulations in TEC have been also observed, confirms the presence of TADs over a wide range of longitudes.

show abstract

Section: Longitudinal Variation Of Vtecmentioning

confidence: 72%

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Sharma¹,

Galav²,

Dashora

et al. 2011

Ann. Geophys.

View full text Add to dashboard Cite

show abstract

“…The morphological features of TEC such as the diurnal, seasonal, latitudinal, and solar activity variations have been investigated by several workers using various techniques over different parts of the globe [Lanyi and Roth, 1988;Goodwin et al, 1995;Abdu et al, 1996;Davies and Hartman, 1997;Mannucci et al, 1998;Afraimovich et al, 2001;Brunini et al, 2003;Jee et al, 2005;Rama Rao et al, 2006;Bagiya Mala et al, 2009;Prasad et al, 2012]. One of the most important electrodynamical features of the equatorial ionosphere is the double-humped latitudinal distribution of ionization centered at the dip equator, which is popularly known as the equatorial ionization anomaly (EIA) [Appleton, 1946].…”

Section: Introductionmentioning

confidence: 99%

On the performance of the IRI‐2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low‐latitude sectors

Venkatesh

Fagundes

Seemala³

et al. 2014

JGR Space Physics

View full text Add to dashboard Cite

It is known that the equatorial and low-latitude ionosphere is characterized with typical dynamical phenomena namely, the equatorial ionization anomaly (EIA). Accurate modeling of the characteristic variations of the EIA is more important to arrive at the correct estimation of range delays required for the communication and navigation applications. The total electron content (TEC) data from a chain of Global Positioning System (GPS) receivers at seven identified locations from equator to the anomaly crest and beyond along 315°E geographic longitude in the Brazilian sector are considered. The performances of the latest available IRI-2012 and NeQuick2 models have been investigated during 2010-2013 in the increasing phase of the 24th solar cycle. A comparative study on the morphological variations of the GPS measured and modeled TEC revealed that the performances of the models are improved during low solar activity periods compared to that during the increased solar activity years. The strength and the locations of the EIA crest are nearly well represented by both the models during the low solar activity while the models underestimate the peak TEC at the EIA during the increased solar activity conditions. The deviations between the GPS-measured and model-derived TEC are more during equinoctial and summer months at and around the anomaly crest locations. Significant differences have also been observed in between the TEC values derived from both the models. The causes for the discrepancies in the modeled TEC values are discussed based on the model-derived and ionosonde-measured vertical electron density profiles variations.

show abstract

“…Kumar et al [81] found the EIA crest in TEC is maximum in equinox months constitute due to EEJ strength. The research of Rama Rao et al [39] reported that the positions of the EIA crest and its [26] found (r = 0.53) over the Brazilian region; Rama Rao et al [39] found (r = 0.62), Bagiya et al [44] found (r = 0.71) and Venkatesh et al [26] found (r = 0.51) in the Indian region stations. Our results agree with this study showing the positive relation between GPS-TEC and EEJ strength.…”

Section: Dependence Of Gps-tec On Eej Strengthmentioning

confidence: 96%

“…The plot in Figure 1 and Figure 2 states that the amplitude of the diurnal maximum is higher in the equinoctial months, which may be due to higher thermospheric [O/N 2 ] ratio and EEJ strength over the Surat station. It is normally accepted that the thermospheric neutral composition has a direct control on the seasonal variation of GPS-TEC [44] [50]. Oryema et al [51] and the references therein reported that, during the daytime in an equinoctial season, the sun is overhead the equator and temperature level at the equator are hotter than at the poles, therefore from the equator meridional wind flows towards the pole.…”

Section: Seasonal Variation Of Gps-tecmentioning

confidence: 99%

GPS-TEC Variation during Low to High Solar Activity Period (2010-2014) under the Northern Crest of Indian Equatorial Ionization Anomaly Region

Patel¹,

Karia²,

Pathak³

2017

POS

View full text Add to dashboard Cite

The measurements of ionospheric TEC (total electron content) are conducted at a low latitude Indian station Surat (21.16˚N, 72.78˚E Geog.), which lies under the northern crest of the equatorial anomaly in Indian region. The data obtained are for a period of five years from low to high solar activity (2010-2014) using GPS (Global Positioning System) receiver. In this study, we report the diurnal and seasonal variation of GPS-TEC, dependence of GPS-TEC with solar activity, geomagnetic condition and EEJ strength. From the seasonal analysis, it is found that greater values of the GPS-TEC are observed during equinox season followed by winter and summer. The appearance (in the year 2011 and 2014) and disappearance (in the year 2010 and 2012) of "winter anomaly" have been observed at the station. From the correlation of GPS-TEC with different solar indices, i.e. solar EUV flux, F10.7 cm solar radio flux and Zurich sunspot number (SSN), it is concluded that the solar index EUV flux is a better controller of GPS-TEC, compared to F10.7 cm and SSN. Further, it is observed that there is no effect of rising solar activity on correlation. Moreover, the percentage variability of GPS-TEC and the standard deviation of GPS-TEC obtained for quiet and disturbed days show that dependence of GPS-TEC on geomagnetic condition is seasonal. Also, there is a positive correlation observed between GPS-TEC and EEJ strength.

show abstract

TEC variations during low solar activity period (2005–2007) near the Equatorial Ionospheric Anomaly Crest region in India

Abstract: Abstract.The dual frequency signals from the GPS satellites recorded at Rajkot (22.29 • N, 70.74 •

Cited by 221 publications

References 34 publications

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

On the performance of the IRI‐2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low‐latitude sectors

GPS-TEC Variation during Low to High Solar Activity Period (2010-2014) under the Northern Crest of Indian Equatorial Ionization Anomaly Region

Contact Info

Product

Resources

About