On the validity of the ionospheric pierce point (IPP) altitude of 350 km in  the Indian equatorial and low-latitude sector

Rao, P. V. S. Rama; Niranjan, K.; Prasad, D. S. V. V. D.; Krishna, S. Gopi; Uma, G.

doi:10.5194/angeo-24-2159-2006

Cited by 145 publications

(69 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Through use of a Kalman filter or sequential leastsquares method, these biases can be removed from the slant TEC measurements; thus an unbiased vertical TEC is obtained (Sardon et al, 1994;Huang et al, 2003). However, large errors are introduced in the estimation of the vertical TEC for the low-latitude region (Rama Rao et al, 2006;Huang and Yuan, 2013). In this study, to minimize the error, we utilize the products provided by the Center for Orbit Determination in Europe (CODE) to estimate the DCBs.…”

Section: A Methods For Estimating the Ionospheric Vertical Tecmentioning

confidence: 99%

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

Huang

Yuan

2015

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. The ionospheric slab thickness is defined as the ratio of the total electron content (TEC) to the ionospheric F2 layer peak electron density (NmF2). In this study, the slab thickness is determined by measuring the ionospheric TEC from dual-frequency Global Positioning System (GPS) data and the NmF2 from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC). A statistical analysis of the diurnal, seasonal and spatial variation in the ionospheric slab thickness is presented along the longitude of 120 • E in China and its adjacent region during the recent solar minimum phase (2007)(2008)(2009). The diurnal ratio, defined as the maximum slab thickness to the minimum slab thickness, and the night-to-day ratio, defined as the slab thickness during daytime to the slab thickness during night-time, are both analysed. The results show that the TEC of the northern crest is greater in winter than in summer, whereas NmF2 is greater in summer than in winter. A pronounced peak of slab thickness occurs during the postmidnight (00:00-04:00 LT) period, when the peak electron density is at the lowest level. A large diurnal ratio exists at the equatorial ionization anomaly, and a large night-to-day ratio occurs near the equatorial latitudes and mid-to high latitudes. It is found that the behaviours of the slab thickness and the F2 peak altitude are well correlated at the latitudes of 30-50 • N and during the period of 10:00-16:00 LT. This current study is useful for improvement of the regional model and accurate calculation of the signal delay of radio waves propagating through the ionosphere.

show abstract

Section: A Methods For Estimating the Ionospheric Vertical Tecmentioning

confidence: 99%

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

Huang

Yuan

2015

Ann. Geophys.

View full text Add to dashboard Cite

show abstract

“…For the purpose of getting better accuracies in the computation of VTEC, the data with satellite elevation angles greater than 50˚ are only used. This reduces the error due to the assumption in the mapping function with the whole ionosphere being condensed into a thin shell around 350 km altitude [22] …”

Section: Single Gps Station Analysismentioning

confidence: 99%

A Novel Approach to Study Regional Ionospheric Variations Using a Real-Time TEC Model

Chakravarty¹

2014

POS

View full text Add to dashboard Cite

Since IGY (International Geophysical Year), through coordinated global observations, ionospheric research has been carried out by many countries. This effort primarily helped in the design and operation of HF radio wave communication systems. The Indian region covers a highly variable part of the equatorial electrojet and EIA (Equatorial Ionisation Anomaly) phenomena making its predictability difficult. With the advent of satellite communication and navigation, the need for accurate ionospheric TEC (Total Electron Content) models at global and regional scales has been stressed. The GAGAN (GPS Aided Geo Augmented Navigation) project jointly undertaken by the Indian Space Research Organisation (ISRO) and the Airport Authority of India (AAI) aims at effectively utilising the Global Navigational Satellite System (GNSS) to determine position coordinates accurately for aircraft precision landing applications. For this purpose the range errors are estimated by using a ground network of TEC stations spread over Indian region. The near simultaneous data collected from these dual frequency GPS stations can be used to generate the geo-referenced TEC values for various applications. The author has developed necessary algorithm and associated computer programmes for a real-time vertical TEC (VTEC) model based on TEC data collected from the GAGAN ground based network stations. The model has been tested and sample results presented here show that it adequately provides for the latitudinal resolution of 1˚ for the entire longitude span and also for two longitude blocks (73 -83 & 83 -93˚E) separately. Cubic spline and bilinear interpolation techniques are used for filling up temporal and spatial data gaps. The model provides tabulated output of hourly average VTEC data with latitude for ready use, as well as graphical displays of VTEC maps and contours for monitoring purpose. The real-time model and its extensions are also being used for detailed scientific studies; examples of these show small day to day variability of VTEC without any change in solar activity and indication of the change in the shape of the VTEC diurnal curve with season. The present model will be used for further studies to derive the monthly average variation of the diurnal pattern and the relationship between VTEC peak amplitudes with changes in solar activity. The new information generated can be fed back to improve the real-time model so that eventually the dependence of such models on ground based network stations data can be minimised.

show abstract

“…The receiver independent exchange (RINEX) format International GNSS Service (IGS) (Dow et al 2009) data are processed using open-source GPS ToolKit (GPSTk) (Harris and Mach 2007;Laskar et al 2013). While calculating vertical TEC values, satellites with elevation angles greater than 50°are considered, which remove the dependence of TEC on ionospheric pierce point height and latitude, in addition to multipath effect in the low latitudes (Rama Rao et al 2006;Bagiya et al 2009). …”

Section: Tecmentioning

confidence: 99%

Vertical coupling of atmospheres: dependence on strength of sudden stratospheric warming and solar activity

Laskar

Pallamraju

Veenadhari³

2014

Earth Planet Sp

View full text Add to dashboard Cite

Comprehensive behavior of the low-latitude upper atmosphere during sudden stratospheric warming (SSW) events at varying levels of solar activity has been investigated. The equatorial electrojet (EEJ) strength and the total electron content (TEC) data from low latitudes over Indian longitudes during the mid-winter season in the years 2005 to 2013 are used in this study. Five major and three minor SSW events occurred in the observation duration, wherein the solar activity had varied from minimum (almost no sunspots) to mini-maximum (approximately 50 sunspots of the solar cycle 24). Spectral powers of the large-scale planetary wave (PW) features in the EEJ and the TEC have been found to be varying with solar activity and SSW strengths. Specially, the spectral powers of quasi-16-day wave variations during the three very strong SSW events in the years 2006, 2009, and 2013 were found to be very high in comparison with those of other years. For these major events, the amplitudes of the semi-diurnal tides and quasi-16-day waves were found to be highly correlated and were maximum around the peak of SSW, suggesting a strong interaction between the two waves. However, this correlation was poor and the quasi-16-day spectral power was low for the minor events. A strong coupling of atmospheres was noted during a relatively high solar activity epoch of 2013 SSW, which was, however, explained to be due to the occurrence of a strong SSW event. These results suggest that the vertical coupling of atmospheres is stronger during strong major SSW events and these events play an important role in enabling the coupling even during high solar activity.

show abstract

On the validity of the ionospheric pierce point (IPP) altitude of 350 km in the Indian equatorial and low-latitude sector

Cited by 145 publications

References 5 publications

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

Climatology of the ionospheric slab thickness along the longitude of 120° E in China and its adjacent region during the solar minimum years of 2007–2009

A Novel Approach to Study Regional Ionospheric Variations Using a Real-Time TEC Model

Vertical coupling of atmospheres: dependence on strength of sudden stratospheric warming and solar activity

Contact Info

Product

Resources

About