The Investigation of Relationship between Solar Parameters and Total Electron Content over Mid-Latitude Ionosphere (original) (raw)

The correlation between total electron content variations and solar activity

2015

Due to the irregularities and dispersive medium of ionosphere, the total electron content (TEC) varies caused by a several factors such as local time (LT), latitude, longitude, season, geomagnetic conditions, solar cycle and activity, and so on. This investigation focused on the correlation between TEC variation and solar activity at an equatorial and polar station. This paper investigated the TEC variation at recent solar cycle 24. 2008 indicates solar minimum period while 2013 indicates solar maximum period. This paper covered analysis on hourly mean TEC value at the equatorial station, Libreville, Gabon (0.354˚N, 9.672˚E) and the polar station, Ny-Alesund, Norway (78.929˚N, 11.865˚E). By using the GPS-TEC analysis application software, the TEC value was extracted from Receiver Independent Exchange (RINEX) observation files. The TEC values increases during solar maximum because of higher solar activities. Additionally, geographic latitude also affects TEC variation, as solar radiation hits directly to the Earth's atmosphere at Libreville station thus more ionization processes occurs. At Ny-Alesund station, winter anomaly causes the TEC values in winter goes high, approximately ~5 TECU in 2008 and ~8 TECU in 2013.

Diurnal, seasonal, latitudinal and solar cycle variation of electron temperature in the topside F-region of the Indian zone ionosphere

Annales Geophysicae, 2007

Electron temperature T e observed by the SROSS C2 satellite at equatorial and low latitudes during the low to high solar activity period of 1995-2001 at the height of ∼500 km is investigated in terms of local time, season, latitude, solar sunspot number R z and F10.7 cm solar flux. The satellite covered the latitude belt of 31 • S-34 • N and the longitude range of 40 •-100 • E. The average nighttime (20:00-04:00 LT) T e varies between 750-1200 K and then rises sharply in the sunrise period (04:00-06:00 LT) to the morning high from 07:00 to 10:00 LT and attains a daytime (10:00-14:00 LT) average of 1100-2300 K. The morning enhancement is more pronounced in the equinoxes. A secondary maximum in T e is also observed around 16:00-18:00 LT in the June solstice and in the equinoxes. Daytime electron temperature was found to be higher in autumn compared to that in spring in all latitudes. Between the solstices, the amplitude of the morning enhancement is higher in winter compared to that in summer. Both day and nighttime T e observed by the SROSS C2 satellite bears a positive correlation with solar activity when averaged on a shorter time scale, i.e. over the period of a month. But on a longer time scale, i.e. averaged over a year, the daytime electron temperature gradually decreases from 1995 till it reaches the minimum value in 1997, after which T e again continues to rise till 2001. The variations are distinctly seen in summer and in the equinoxes. The sunspot activity during solar cycle 23 was minimum in 1996 and maximum in 2000. Annual average electron temperature, therefore, appears to follow the variation of solar activity with a time lag of about one year, both at the bottom and top of solar cycle 23, indicating an inherent inertia of the ionosphere thermosphere regime to variations in solar flux.

Diurnal, seasonal and solar cycle variation of total electron content and comparison with the IRI-2016 model at Birnin Kebbi

Annales Geophysicae Discussions

Total Electron Content (TEC) is an important ionospheric parameter used to monitor possible space weather impacts on satellite to ground communication and satellite navigation system. TEC is modified in the ionosphere by changing solar Extreme UltraViolet (EUV) radiation, geomagnetic storms, and the atmospheric waves that propagate up from the lower atmosphere. Therefore, TEC depends on local time, latitude, longitude, season, geomagnetic conditions, solar cycle activity, and condition of the troposphere. A dual frequency GPS receiver located at an equatorial station, Birnin-Kebbi in Northern Nigeria (geographic location: 12.64°N; 4.22°E), has been used to investigate variation of TEC during the period of 2011 to 2014. We investigate the diurnal, seasonal and solar cycle dependence of observed (OBS) TEC and comparison with latest version of International Reference Ionosphere (IRI-2016) model. On a general note, diurnal variation reveals discrepancies between OBS-TEC and IRI-2016 model for all hours of the day except during the post-midnight hours. Slight post-noon peaks in the daytime maximum and post-sunset decrease and enhancement are observed in the diurnal variation of OBS-TEC of some months. On a seasonal scale, we observed that OBS-TEC values were higher in the

Variations in Total Electron Content During the Phases of Low and High Solar Activities

Jurnal teknologi, 2016

Variations in the Total Electron Content of the ionosphere were studied by utilizing data from the GISTM receiver installed at Universiti Tun Hussein Onn Malaysia. The study was conducted during periods of low solar activity (July 2007-July 2008) and high solar activity (July 2013-July 2014). Results show that the TEC are dependent on the solar activity.The values during high solar activity were significantly higher than that obtained during the solar minimum phase. The minimum TEC values for both phases varied between 89% and 97%, and the maximum TEC values varied between 70% and 81%. The pattern of daily TEC value changes was constant, and TEC peaked in the afternoon at ~14 LT. The highest TEC recorded during the solar maximum phase was 144.5 TEC Unit (TECU) in April 2014, whereas the highest TEC recorded during the solar minimum phase was 36.3 TECU in April 2008. TEC was maximized from March to May under both solar maximum and minimum phases.

Day-to-day changes in ionospheric electron content at low latitudes

Radio Science, 1984

The day-today variability in ionospheric electron content (IEC) is studied using the diurnal IEC maximum data obtained from multistations located in the latitude range between 15.0øN and 30.0øN in the Indian zone during solar minimum. Depending on the location of the observing station, the changes in IECmax values, of about + 20 to 40%, are found to occur in the form of single day abnormality, alternate day abnormality, and long-term periodic fluctuations. The magnitude of fluctuations is found to be maximum at a station which is near the crest of the equatorial anomaly belt. The long-term periodic variations, other than annual and semiannual variations, are different for different locations and seasons and show a periodicity of about 45 days in winter in the equatorial anomaly region only and about 27 days in summer at all the stations. The changes are not always correlated with solar or magnetic activity changes. It is observed that short-as well as long-term variations in IECma x at stations within and near the crest of the equatorial anomaly belt are controlled mainly by the electrojet strength variation. '• Now at Oil and Natural Gas Commission, Ahmedabad, India.

Variability of ionospheric TEC at low latitude station, Hyderabad during medium solar activity

Russian Journal of Earth Sciences, 2021

The successful operation of communicational and navigational applications requires knowledge of state and behaviour of ionosphere as well as spatial and temporal changes taking place in it. With this view, we have studied the variability and changes in the low latitude ionosphere by considering a low latitude Indian station Hyderabad (17.41 ∘ N, 78.55 ∘ E). The variability is studied during the year 2014, by using the space borne Global Positioning System (GPS) observations. From GPS observations an important parameter; Total Electron Content (TEC) is obtained, which represents the integral electron density of the ionosphere and is widely used in studies concerning ionospheric variability. We have studied how the ionospheric conditions at Hyderabad change from hour to hour, day to day, month to month and season to season. We found that ionosphere over Hyderabad exhibits significant, interesting and regular variability. Although, the trends followed by the ionospheric changes are similar, but the magnitude of peak values differ on different time scales. Finally we have compared the variability of observed or actual values of TEC with the corresponding values predicted by International Reference Ionosphere (IRI) model-2016 and found good agreement between hourly values, while IRI model overestimates or underestimates the daily values.

Diurnal, seasonal and solar-cycle variations of electron densities in the ionospheric D- and E-regions

Journal of Atmospheric and Terrestrial Physics, 1977

A.hatzaet--Mean electron density profiles for the height region between 65 and 110 km are derived for medium latitudes in dependence on solar zenith angle, solar activity and season from radio wave propagation data in the frequency range between about 10 and 25OOkHz. Starting with an initial profile, the electron density profile is iteratively adjusted until the theoretical propagation data calculated from this profile satisfactorily agree with the experimental data. The results show a general enhancement of electron density with increasing solar activity in the whole height region. Evaluation of the seasonal variation shows that the lowest values of electron density in the lower ionosphere are found in April, whereas in winter the electron density is strongly enhanced above 83 km. This winter-time increase of electron density together with the enhancement of collision frequency causes the winter anomaly well-known from radio wave propagation measurements.

The Effect of Sunspots Number on the Total Electron Content (TEC) of the Ionospheric Layer E Over Kirkuk Station for Solar Cycle 24

Kirkuk University Journal-Scientific Studies

In this work, the effect of sunspots number (Ri) on the Total electronic content (TEC) were studied for the years (2008, 2014, 2018) which represents the rising phase, the peak and the down phase of the solar cycle 24 over Kirkuk station in Iraq at latitude 35° North and longitude 44° East, by finding the TEC values for the Elayer, the layer ' s impression times are determined for the days of solstice and equinox. In this study the International Reference Ionosphere program (IRI) program have been applied to find the values of TEC which provided by the space research committee (COSPAR) and International Union of Radio Sciences (URSI), IRI have three upper side electron density options. The accuracy of this study was verified by the application conducted of the university of Hacettepe in Ankara, Turkey by matching the reading of TEC from Global Position System (GPS) with output data of TEC from the IRI for Ankara station which located at (39.7 N;32.76 E). And from this investigation turns out that the output data from the option IRI2001 was more consistent with reading of the GPS, than the rest of the other options. From this study by using the statistical program Minitab version 2018. There is a strong correlation between the Total Electron Content (TEC) of Ionospheric layer E and Sunspot number for solar cycle 24.