Mehmet AYDOĞDU, Esat GÜZEL, Ali YEŞİL Fırat Üniversitesi Fen-Edebiyat Fakültesi, Fizik Bölümü, 23... more Mehmet AYDOĞDU, Esat GÜZEL, Ali YEŞİL Fırat Üniversitesi Fen-Edebiyat Fakültesi, Fizik Bölümü, 23119 ELAZIĞ [email protected], [email protected], [email protected] ... ÖZET: Bu çalışmada, elektronların diğer parçacıklarla çarpışmasının elektromanyetik ...
In this study, the effect of the different modes of the HF radio waves used in radio communicatio... more In this study, the effect of the different modes of the HF radio waves used in radio communication to the electron temperature have been investigated daily, seasonal and with sunspot at subionosphere. The relationship between electron density and increase at the electron temperature caused by the wave are inversely proportional at subionosphere. Also, the temperature increase is quite low at the maximum sunspot. The highest and lowest temperature values were observed in the R-mode and L-mode respectively. The highest temperature values were about 70-80 km for all modes.
Journal of Atmospheric and Solar-Terrestrial Physics, 2004
... Mehmet Aydo du Corresponding Author Contact Information , E-mail The Corresponding Author , A... more ... Mehmet Aydo du Corresponding Author Contact Information , E-mail The Corresponding Author , Ali Ye l and Esat Güzel. ... In earlier studies (Al'pert, 1980; Budden and Stott, 1980; Hagfors, 1984; Lundborg and Thide, 1986; Budden, 1988; Zhang, 1991; Aydogdu and Özcan 1996 ...
International Journal of Antennas and Propagation, 2013
Longitudinal analysis models are applied to analyze very low frequency (VLF) electromagnetic wave... more Longitudinal analysis models are applied to analyze very low frequency (VLF) electromagnetic waves signals. They are useful in realization of nuance of relationship between parameters of concern which change over time. VLF data are so important for the communication and determining the disturbances in the lower ionosphere. In this study, we used a four-day VLF signal data which come from transmitter stations located at two different countries to Elazıg receiver system. A very important feature of this data is that there is a strong relationship between days and signals. At first, the exploratory data analysis was applied for identification of data. Then, marginal, random-effects, and transitional models were used to analyze the data, respectively. The marginal model is found more appropriate than the other models used for VLF data analyses. As a result of this process, a new method has been added to the analysis of VLF signal data.
In this paper, the changes in the ionosphere over Turkey due to two solar eclipses are reported. ... more In this paper, the changes in the ionosphere over Turkey due to two solar eclipses are reported. TEC on the eclipse day (26 April 1976) and the intensity of an HF radio wave during its propagation over 567 km between Ankara and Elazıǧ on the eclipse day (11 August 1999) exhibited a very marked decrease.
Journal of Physical Chemistry and Functional Materials, 2021
In this study, the relationship between Schumann resonance frequencies (SRF) and the Geomagnetic ... more In this study, the relationship between Schumann resonance frequencies (SRF) and the Geomagnetic indices (Dst, kp) was statically inquired. The relationship between the data of Schuman resonance frequencies for the first five months of 2016 and the values of hourly average of Dst and three-hour average of Kp was determined by applying the correlation analysis separately. The highest correlation coefficients are found-12.4% for SRF-Dst at 35 Hz,-11.6% for SRF-Kp*10 at 7 Hz.
Bu calismada, dalgacik donusumunun cok cozunurluk analizi ile alt iyonkurede olusan olaylari tesp... more Bu calismada, dalgacik donusumunun cok cozunurluk analizi ile alt iyonkurede olusan olaylari tespit etmek amaciyla kullanilan uzaktan algilanan VLF sinyallerinde olusan ani degisimlerindeki gurultulerin giderilmesi gerceklestirilmistir. Bu amacla, 102 farkli dalgacik ailesi incelenerek PSNR degerleri ile en uygun sonuc ya da sonuclarin bulunmasina calisilmistir. Sonuclar hem tablolar hem de gurultusu giderilmis VLF sinyalleri ile gosterilmistir.
Bu calismada, alt iyonkurede yayilan VLF sinyallerinde olusan yildirim kaynakli olaylari otomatik... more Bu calismada, alt iyonkurede yayilan VLF sinyallerinde olusan yildirim kaynakli olaylari otomatik olarak tespit etmek amaciyla dalgacik donusumu kullanilarak bir MATLAB yazilimi gerceklestirilmistir. Bu yazilimin ciktilari ile gercek sonuclar istatiksel olarak karsilastirilarak yazilimin guvenirliligi test edilmistir. Sonuc olarak her ikisinin de ayni guven araliginda oldugu tespit edilmistir.
Abstract In this theoretical study, the noise temperature of the different modes (ordinary, extra... more Abstract In this theoretical study, the noise temperature of the different modes (ordinary, extraordinary, right and left polarized) of the electromagnetic wave travelling vertically in the ionosphere has been investigated for the solstice and the equinox days, 2015. The noise temperature values vary between 10−6 and 10−2 K for all results. There is a slight decrease in the noise temperature values near the 105 km and then a rise again for 4, 5, 6 MHz waves at all modes. As the frequency of the wave increases, the noise temperature values change periodically depending on the electron density.
The absorption (L) of the wave in the ionosphere has been calculated. The wave (5.47 MHz) is tran... more The absorption (L) of the wave in the ionosphere has been calculated. The wave (5.47 MHz) is transmitted from Ercis-Turkey (39.03°N, 43.37°E) and received at Elazig-Turkey (38.70°N, 39.20°E). The field strength of this wave is measured by ITU-Compliant HF Field Strength Monitoring Terminal, and the absorption L in the ionosphere has been calculated. It is observed that the field strength
Solar flares cause sudden disturbances at the Earth's ionosphere. These effects are detected by t... more Solar flares cause sudden disturbances at the Earth's ionosphere. These effects are detected by the very low frequency (VLF), 3−30-kHz signals which are propagated at the Earth-ionosphere waveguide. The sudden changes on the time-dependent intensity of VLF signals are recorded by Super SID system during February, March, and April, 2013. Then VLF data were compared with the GOES satellite data found in the Space Environment Center online database. The main factors of the variation in VLF signal intensities recorded by the Super SID system are class, duration of the solar flare and the frequency of VLF signals.
Bitlis Eren Üniversitesi Fen Bilimleri Dergisi, 2016
Bu çalışmada, 8 Aralık 1978 tarihindeki, Kashima yer istasyonundan 90º K ile 90º G enlemleri ve 3... more Bu çalışmada, 8 Aralık 1978 tarihindeki, Kashima yer istasyonundan 90º K ile 90º G enlemleri ve 30, 35, 40, 45 derece Doğu boylamları için oluşturulan haritalar kullanılarak elde edilen iyonkürenin F2-bölgesinin kritik frekansının (foF2) değişimleri Uluslararası İyonküre Referans Modelinden (IRI) elde edilen değerlerle karşılaştırmalı olarak incelenmiştir. Deneysel ve teorik veriler karşılaştırıldığında kritik frekans değerlerinin kutuplardan ekvatora doğru gidildikçe arttığı ve ekvator üzerinde çukurlar ile 20º K ve 20º G enlemleri arasında tepeler oluştuğu gözlenmiştir. 30 boylamından 45 boylamına gidildikçe kritik frekans değerleri deneysel verilerde artarken teorik verilerde azaldığı görülmektedir
The absorption (L) of the wave in the ionosphere has been calculated. The 5.47 MHz wave is transm... more The absorption (L) of the wave in the ionosphere has been calculated. The 5.47 MHz wave is transmitted from Erciş, Turkey (39.03 • N, 43.37 • E) and received at Elazıg, Turkey (38.70 • N, 39.20 • E). The field strength of this wave is measured by ITU-Compliant HF Field Strength Monitoring Terminal, and the absorption L in the ionosphere has been calculated. It is observed that the field strength of the wave is least around noon time and it increases at night times at all seasons. The diurnal and seasonal variations of the calculated absorption L shows that the maximum absorption in the wave occurs around noon time. The behaviour of the diurnal and seasonal variations of the field strength of the wave can be explained with the diurnal and seasonal variations of the calculated absorption L in the ionosphere. Equation (22) in this paper can be used to obtain the imaginary part (β) of the refractive index of the ionospheric plasma, and it can be applied to the HF radio waves propagations in the ionosphere for absorption L.
In this study, the eect of the actual geometry of the magnetic eld on the electron temperature ha... more In this study, the eect of the actual geometry of the magnetic eld on the electron temperature has been investigated daily and seasonally for the electromagnetic wave travelling at subionosphere. The electron energy balance equation has been obtained by using the ideal gas approximation. The results show that there are notable dierences between the two situations (B k z and B real, z). According to our theoretical study, the maximum changes are shown at Land R-mode, small eect on X-mode and no variation on O-mode due to the real geometry of the magnetic eld. Besides, the heights of the maximum points are changeable daily and seasonally for all modes at the subionosphere.
Mehmet AYDOĞDU, Esat GÜZEL, Ali YEŞİL Fırat Üniversitesi Fen-Edebiyat Fakültesi, Fizik Bölümü, 23... more Mehmet AYDOĞDU, Esat GÜZEL, Ali YEŞİL Fırat Üniversitesi Fen-Edebiyat Fakültesi, Fizik Bölümü, 23119 ELAZIĞ [email protected], [email protected], [email protected] ... ÖZET: Bu çalışmada, elektronların diğer parçacıklarla çarpışmasının elektromanyetik ...
In this study, the effect of the different modes of the HF radio waves used in radio communicatio... more In this study, the effect of the different modes of the HF radio waves used in radio communication to the electron temperature have been investigated daily, seasonal and with sunspot at subionosphere. The relationship between electron density and increase at the electron temperature caused by the wave are inversely proportional at subionosphere. Also, the temperature increase is quite low at the maximum sunspot. The highest and lowest temperature values were observed in the R-mode and L-mode respectively. The highest temperature values were about 70-80 km for all modes.
Journal of Atmospheric and Solar-Terrestrial Physics, 2004
... Mehmet Aydo du Corresponding Author Contact Information , E-mail The Corresponding Author , A... more ... Mehmet Aydo du Corresponding Author Contact Information , E-mail The Corresponding Author , Ali Ye l and Esat Güzel. ... In earlier studies (Al'pert, 1980; Budden and Stott, 1980; Hagfors, 1984; Lundborg and Thide, 1986; Budden, 1988; Zhang, 1991; Aydogdu and Özcan 1996 ...
International Journal of Antennas and Propagation, 2013
Longitudinal analysis models are applied to analyze very low frequency (VLF) electromagnetic wave... more Longitudinal analysis models are applied to analyze very low frequency (VLF) electromagnetic waves signals. They are useful in realization of nuance of relationship between parameters of concern which change over time. VLF data are so important for the communication and determining the disturbances in the lower ionosphere. In this study, we used a four-day VLF signal data which come from transmitter stations located at two different countries to Elazıg receiver system. A very important feature of this data is that there is a strong relationship between days and signals. At first, the exploratory data analysis was applied for identification of data. Then, marginal, random-effects, and transitional models were used to analyze the data, respectively. The marginal model is found more appropriate than the other models used for VLF data analyses. As a result of this process, a new method has been added to the analysis of VLF signal data.
In this paper, the changes in the ionosphere over Turkey due to two solar eclipses are reported. ... more In this paper, the changes in the ionosphere over Turkey due to two solar eclipses are reported. TEC on the eclipse day (26 April 1976) and the intensity of an HF radio wave during its propagation over 567 km between Ankara and Elazıǧ on the eclipse day (11 August 1999) exhibited a very marked decrease.
Journal of Physical Chemistry and Functional Materials, 2021
In this study, the relationship between Schumann resonance frequencies (SRF) and the Geomagnetic ... more In this study, the relationship between Schumann resonance frequencies (SRF) and the Geomagnetic indices (Dst, kp) was statically inquired. The relationship between the data of Schuman resonance frequencies for the first five months of 2016 and the values of hourly average of Dst and three-hour average of Kp was determined by applying the correlation analysis separately. The highest correlation coefficients are found-12.4% for SRF-Dst at 35 Hz,-11.6% for SRF-Kp*10 at 7 Hz.
Bu calismada, dalgacik donusumunun cok cozunurluk analizi ile alt iyonkurede olusan olaylari tesp... more Bu calismada, dalgacik donusumunun cok cozunurluk analizi ile alt iyonkurede olusan olaylari tespit etmek amaciyla kullanilan uzaktan algilanan VLF sinyallerinde olusan ani degisimlerindeki gurultulerin giderilmesi gerceklestirilmistir. Bu amacla, 102 farkli dalgacik ailesi incelenerek PSNR degerleri ile en uygun sonuc ya da sonuclarin bulunmasina calisilmistir. Sonuclar hem tablolar hem de gurultusu giderilmis VLF sinyalleri ile gosterilmistir.
Bu calismada, alt iyonkurede yayilan VLF sinyallerinde olusan yildirim kaynakli olaylari otomatik... more Bu calismada, alt iyonkurede yayilan VLF sinyallerinde olusan yildirim kaynakli olaylari otomatik olarak tespit etmek amaciyla dalgacik donusumu kullanilarak bir MATLAB yazilimi gerceklestirilmistir. Bu yazilimin ciktilari ile gercek sonuclar istatiksel olarak karsilastirilarak yazilimin guvenirliligi test edilmistir. Sonuc olarak her ikisinin de ayni guven araliginda oldugu tespit edilmistir.
Abstract In this theoretical study, the noise temperature of the different modes (ordinary, extra... more Abstract In this theoretical study, the noise temperature of the different modes (ordinary, extraordinary, right and left polarized) of the electromagnetic wave travelling vertically in the ionosphere has been investigated for the solstice and the equinox days, 2015. The noise temperature values vary between 10−6 and 10−2 K for all results. There is a slight decrease in the noise temperature values near the 105 km and then a rise again for 4, 5, 6 MHz waves at all modes. As the frequency of the wave increases, the noise temperature values change periodically depending on the electron density.
The absorption (L) of the wave in the ionosphere has been calculated. The wave (5.47 MHz) is tran... more The absorption (L) of the wave in the ionosphere has been calculated. The wave (5.47 MHz) is transmitted from Ercis-Turkey (39.03°N, 43.37°E) and received at Elazig-Turkey (38.70°N, 39.20°E). The field strength of this wave is measured by ITU-Compliant HF Field Strength Monitoring Terminal, and the absorption L in the ionosphere has been calculated. It is observed that the field strength
Solar flares cause sudden disturbances at the Earth's ionosphere. These effects are detected by t... more Solar flares cause sudden disturbances at the Earth's ionosphere. These effects are detected by the very low frequency (VLF), 3−30-kHz signals which are propagated at the Earth-ionosphere waveguide. The sudden changes on the time-dependent intensity of VLF signals are recorded by Super SID system during February, March, and April, 2013. Then VLF data were compared with the GOES satellite data found in the Space Environment Center online database. The main factors of the variation in VLF signal intensities recorded by the Super SID system are class, duration of the solar flare and the frequency of VLF signals.
Bitlis Eren Üniversitesi Fen Bilimleri Dergisi, 2016
Bu çalışmada, 8 Aralık 1978 tarihindeki, Kashima yer istasyonundan 90º K ile 90º G enlemleri ve 3... more Bu çalışmada, 8 Aralık 1978 tarihindeki, Kashima yer istasyonundan 90º K ile 90º G enlemleri ve 30, 35, 40, 45 derece Doğu boylamları için oluşturulan haritalar kullanılarak elde edilen iyonkürenin F2-bölgesinin kritik frekansının (foF2) değişimleri Uluslararası İyonküre Referans Modelinden (IRI) elde edilen değerlerle karşılaştırmalı olarak incelenmiştir. Deneysel ve teorik veriler karşılaştırıldığında kritik frekans değerlerinin kutuplardan ekvatora doğru gidildikçe arttığı ve ekvator üzerinde çukurlar ile 20º K ve 20º G enlemleri arasında tepeler oluştuğu gözlenmiştir. 30 boylamından 45 boylamına gidildikçe kritik frekans değerleri deneysel verilerde artarken teorik verilerde azaldığı görülmektedir
The absorption (L) of the wave in the ionosphere has been calculated. The 5.47 MHz wave is transm... more The absorption (L) of the wave in the ionosphere has been calculated. The 5.47 MHz wave is transmitted from Erciş, Turkey (39.03 • N, 43.37 • E) and received at Elazıg, Turkey (38.70 • N, 39.20 • E). The field strength of this wave is measured by ITU-Compliant HF Field Strength Monitoring Terminal, and the absorption L in the ionosphere has been calculated. It is observed that the field strength of the wave is least around noon time and it increases at night times at all seasons. The diurnal and seasonal variations of the calculated absorption L shows that the maximum absorption in the wave occurs around noon time. The behaviour of the diurnal and seasonal variations of the field strength of the wave can be explained with the diurnal and seasonal variations of the calculated absorption L in the ionosphere. Equation (22) in this paper can be used to obtain the imaginary part (β) of the refractive index of the ionospheric plasma, and it can be applied to the HF radio waves propagations in the ionosphere for absorption L.
In this study, the eect of the actual geometry of the magnetic eld on the electron temperature ha... more In this study, the eect of the actual geometry of the magnetic eld on the electron temperature has been investigated daily and seasonally for the electromagnetic wave travelling at subionosphere. The electron energy balance equation has been obtained by using the ideal gas approximation. The results show that there are notable dierences between the two situations (B k z and B real, z). According to our theoretical study, the maximum changes are shown at Land R-mode, small eect on X-mode and no variation on O-mode due to the real geometry of the magnetic eld. Besides, the heights of the maximum points are changeable daily and seasonally for all modes at the subionosphere.
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