Study of Equatorial Ionospheric Scintillation and TEC characteristics at Solar minimum using GPS-SCINDA data (original) (raw)
Related papers
2011 XXXth URSI General Assembly and Scientific Symposium, 2011
Ionospheric scintillation is a rapid variation in the amplitude and phase of trans-ionospheric radio signal resulting from density irregularities in the ionosphere. It is referred to us by the index S4. The data used are the scintillation index (S4) and the vertical TEC (VTEC) recorded at the SCINDA (Scintillation Network Decision Aid) GPS station of Abidjan (Latitude = 5.34 o N, Longitude = 3.90 o W). This work covers the period from January 2008 to January 2009, two years of low solar activity with R12 equal to 2.8 and 4.2 respectively. The results show that the scintillation is not intense with S4 values lower than 1 in most of the cases and during the course of the day. However, from 2000 to 0200 there are relatively high values of S4 confirming that scintillation is primarily a nighttime observed phenomenon. The scintillation shows a seasonal effect characterized by intense value in the equinoctial months compare to that of the solstice season. The VTEC in general exhibits a diurnal variation as a function of the solar zenith angle. Higher VTEC values are observed around 1100 and 1800 local time and have the same seasonal variation with the S4 index.
Journal of Physics: Conference Series, 2019
Ionosphere scintillation and total electron content (TEC) measurement were investigated in terms of value at Equatorial based on GPS/GNSS measurement. This paper presents the analysis month-to-month variation of Scintillation (S4) and Total Electron Content (TEC) based on during night time and day time activity. This paper also presents the analysis of scintillation (S4) and Total Electron Content (TEC) during equinox and solstice. The analysis presented from January to December 2016. The measurement and recorded data of scintillation (S4) and Total Electron Content (TEC) was done by GPS Ionosphere Scintillation and TEC Monitoring (GISTM), installed at UKM, Malaysia (2.92°N 101.78°E). Strong Scintillation (S4) was obtained from PRN 135 with S4 ≥ 0.4 (0.430368) on 11:33 UTC (19:33 UT). The maximum Total Electron Content (TEC) was found on midday, generally the daily peak is around 5:00 to 10:00 UTC (13:00 to 18:00LT). April shows that the highest Total Electron Content (TEC) about 152 TECU. For seasonal variation, Scintillation (S4) highest on equinox and lowest on solstice, meanwhile Total Electron Content (TEC) highest on equinox and lowest on solstice. The disturbance will cause error in distance measurement for positioning and navigation.
Total electron content and scintillations over Maseno, Kenya, during high solar activity year
Acta Geophysica, 2019
Proper characterization of total electron content (TEC) and scintillation is very important to global positioning system (GPS) users in communication, navigation, ionospheric or atmospheric studies. Quiet time variation of TEC is useful in the estimation and removal of ionospheric delay for global navigation satellite systems single-frequency positioning. During geomagnetic storms, the variations of ionosphere deviate from their quiet day pattern and can cause significant effects on short-term prediction of various ionospheric parameters. The dynamics of the ionosphere change from region to region; therefore, in order to evaluate and improve the performance of global models of the ionosphere, numerous studies of variations using measured ionospheric parameters from stations globally are useful. This paper presents for the first time variations in the TEC and scintillation at Maseno University (geomagnetic coordinates, 9.64°S, 108.59°E), Kenya, investigated using a NovAtelGSV400B GPS receiver for the high solar activity year 2014. The GPS-measured TEC values were compared with the modeled TEC values by the latest International Reference Ionosphere model (IRI-2016), with a view to evaluate the performance of this version of the model. The largest TEC values were observed from 1300 to 1500 h local time throughout the year with the largest diurnal values occurring in March equinox and smallest during June solstice. The largest TEC values are attributed to extreme ultraviolet radiation coupled with upward ⃗ E × ⃗ B plasma drift velocity. Nighttime enhancements in TEC attributed to the 'fountain' effect occurred during some months. Scintillation correlated with depletions in TEC occurred in the period between 1600 h local time to 1900 h local time (post-sunset) sector during some months, with the strongest value of − 0.91 being experienced in March equinox. Scintillation was absent during geomagnetic storms studied mainly as a result of the time of onset of the recovery phases of the storms. In addition, the geomagnetic storms were manifested in GPS-measured TEC as negative ionospheric storms. The IRI-2016 model gave a good prediction of measured values except for its overestimation of measured TEC in the months of May and June. Further, a new insight shown by the results is the ability of the IRI-2016 model to predict post-sunset TEC enhancements during some months contrary to previous versions reported by other researchers in East Africa. However, model is not quickly sensitive to transitions from one season to another. This result contributes to the improvement of the current IRI model by recommending the introduction of an input into the model that is sensitive to transitions in seasons in future versions of the model.
Radio Science, 2013
Ionospheric plasma density irregularities are a common feature of the equatorial and low-latitude ionosphere. These irregularities are known to cause fading and phase fluctuation (scintillation) of L-band radio navigation signals such as those used by Global Navigation Satellite Systems. This study investigates the occurrence of intense ionospheric scintillation in the postsunset period during a geomagnetically quiet day on 8 April 2011. In particular, we use Global Positioning System (GPS) derived observations, i.e., total electron content (TEC) and amplitude scintillation intensity index, S4, to examine the occurrence of intense scintillations at two low-latitude stations in the East African sector. Deep TEC depletions, in some cases roughly 40 TECU, are observed consistently with the occurrence of intense scintillations. In addition, we compare the GPS-based observations to the Communication/Navigation Outage Forecasting System (C/NOFS) satellite plasma data. The intense scintillation events also correspond well with plasma depletion structures present on the C/NOFS observations and can be attributed to strong plasma bubble activity. The C/NOFS data also provide evidence of strong upward drift velocities (> 60 m/s) associated with the depletions, which may have contributed to the generation of the strong irregularities.
The present paper reports the occurrence of ionospheric scintillation (S4 > 0.2) measured using GPS receiver (GISTM) at Surat, (21.160N, 72.780E) located near the northern crest of equatorial anomaly in India. The results are presented for data collected during di�erent levels of solar activity from Jan-2009 to Dec-2011. These long time observations phenomenon, which covers low to moderate solar activity period, have shown features such as, diurnal, monthly, seasonal, magnetic activity and solar cycle variation in scintillation occurrence. It was observed that the diurnal variation of the amplitude scintillation predominately occurred after sunset time (18:00 to 06:00 LT). Our observation shows that the duration of scintillation occurrence is found to be maximum during moderate solar activity and least during low solar activity. The seasonal variation shows that the occurrence of scintillation is observed to be maximum for equinox months, less in winter months and least in summer...
A study of L-band scintillations and total electron content at an equatorial station, Lagos, Nigeria
Radio Science, 2012
In this paper we present the first results from measurements of scintillation and total electron content (TEC) from an equatorial station, Lagos (Latitude 6.5 N, Longitude 3.4 E, magnetic latitude 3.03 S), Nigeria, using a Novatel GSV4004B GPS ionospheric scintillation and TEC monitor. Details are presented for data collected between February 2010 and August 2010. The results show that the presence of some large scale depletions of TEC or plasma bubbles may be noted during the evening hours and that TEC depletions correspond to increased rate of change of TEC (ROT). This confirms that plasma bubbles are associated with large scale irregularities. It is also established that enhanced amplitude scintillation (S 4) corresponds quite well with TEC depletions and increases in ROT. The diurnal and seasonal percentage occurrence for different levels of scintillation activity has peaks in the equinox months (March and April) at 23:00 LT.
2019
At our location we have frequent occurrence of weak ionospheric scintillations, while few intense scintillations. Intense scintillation occurred during the day time with a small frequency and relatively moderate scintillation occurrence during the night time with very frequent occurrence of scintillation. The maximum numbers of amplitude scintillation events are observed in equinox and minimum in summer.