YÜKSEK ENLEM foF2 DEĞERLERİNDEKİ DEĞİŞİMLERİN JEOMANYETİK AKTİVİTEYE BAĞLILIĞI

Öz

Bu çalışmada, Aralık 1971-Eylül 1972 tarihleri arasında yüksek enlem bölgesi olarak tanımlanan 60^o-90^o değişmeyen manyetik enlem arasındaki 7 iyonsonda istasyonundan alınan saatlik foF2 verilerinin değişmeyen manyetik enleme göre değişimleri, farklı jeomanyetik aktivite durumları için incelenmiştir. Analizlerden elde edilen sonuçlara göre, gündüz saatlerindeki foF2 değerlerinin, gece saatlerindeki değerlerden büyük olduğu, ayrıca bu saatlerde foF2 değerlerinin değişmeyen manyetik enlem artışı ile 68^o-72^o değişmeyen manyetik enlemleri arasındaki artış dışında azaldığı tespit edilmiştir. Gece saatlerinde ise foF2 değerlerinin yaklaşık 66^o-72^o değişmeyen manyetik enlemleri arasında arttığı, bu enlemlerden daha büyük ve daha küçük enlemlerde ise foF2 değerlerinin azalarak çukura benzer bir yapı oluşturduğu gözlemlenmiştir. Ayrıca mevsimsel ve jeomanyetik aktivite değişimlerinin, foF2 değerlerinin enlemsel değişimleri üzerinde önemli bir etkiye sahip olduğu tespit edilmiştir. Jeomanyetik pasif durumdaki foF2 değerleri, jeomanyetik aktif durumdaki foF2 değerlerinden büyüktür. Özellikle jeomanyetik aktif durumdaki Aralık döneminde, polar cap ve polar oval bölgeleri daha belirgin ve bu bölgeler enlemsel olarak daha geniş bir yapıya sahiptir.

Anahtar Kelimeler

• Yüksek enlem iyonosferi,Manyetosfer,Jeomanyetik aktivite

THE DEPENDENCE ON THE GEOMAGNETIC ACTIVITY OF CHANGES IN THE foF2 VALUES AT THE HIGH LATITUDES

Öz

In this study, changes according to invariant magnetic latitude of the hourly foF2 data that are taken from seven ionosondes stations are situated at between 60^o-90^o invariant magnetic latitude as known high latitude region are investigated for different geomagnetic activity conditions during December 1971-September 1972. According to the results obtained from the analyzes, it was found that the foF2 values in the daytime are larger than those in the nighttime, and the foF2 values in these hours decreases with the increasing of the invariant magnetic latitude the except for between about 68^o and 72^o invariant magnetic latitude. At night time, it was observed that the foF2 values increases between about 66^o and 72^o invariant magnetic latitude, while the foF2 values exhibit a trough structure at larger and smaller latitudes than these latitudes. It is also observed that seasonal and geomagnetic activity changes have a significant influence on the latitudinal changes of the foF2 values. The foF2 values in the geomagnetic quiet condition are larger than the foF2 values in the geomagnetic active conduction. Especially in the geomagnetic active conduction of the December, the polar cap and polar oval zones are more prominent and have a larger latitudinal structure.

Anahtar Kelimeler

• High latitude ionosphere,Magnetosphere,Polar region,Geomagnetic activity

Kaynakça

1. Rishbeth H, Garriott OK. Introduction to Ionospheric Physics. New York, USA: Academic Press, 1969.
2. Banks M, Kockarts G. Aeronomy Part A. New York, USA: Academic Press, 1973.
3. Rishbeth H. Physics and chemistry of the ionosphere. Contemp Physics 1973; 14: 229-249.
4. Kelley MC. The Earth’s Ionosphere (Plasma Physics and Electrodynamics). New York, USA: Academic Press, 1989.
5. Schunk RW, Nagy AF. Ionospheres. New York, USA: Cambridge University Press, 2000.
6. Kivelson MG, Russell CT. Introduction to Space Physics. New York, USA: Cambridge University Press, 1995.
7. Prölss GW. Physics of the Earth’s Space Environment. Berlin-Heidelberg-New York, DE, USA: Springer-Verlag Press, 2004.
8. Tascione TF. Introduction to the Space Enviroment. Florida, USA: Orbit Book Company, 1988.

9. Ezquer RG, Cabrera MA, Lo´pez JL, Albornoz MR, Mosert M, Marco P, Buresova D. Critical frequency and maximum electron density foF2 region over four stations in the north american sector. Journal of Atmospheric and Solar-Terrestrial Physics 2011; 73: 420-429.
10. Maltseva OA, Mozhaeva NS, Nikitenko TV. Comparison of model and experimental ionospheric parameters at high latitudes. Advances in Space Research 2013; 51: 599–609.
11. Atukkar R, Bhardwaj S, Khatarkar P, Bhawre P. Geomagnetic disturbances and its impact on ionospheric critical frequency (fof2) at high, mid and low latitude region. American Journal of Astronomy and Astrophysics 2014; 2(6): 61-65.
12. Khatarkar P, Purohit PK, Gwal AK. Study of ionospheric f2 layer characteristics at low, mid and high latitudes. International Journal of Science and Research 2014; 3: 1509-1513.
13. Atulkar R, Bhardwaj S, Khatarkar P, Bhawre P, Purohit PK. Geomagnetic disturbances and its impact on ionospheric critical frequency (foF2) at high, mid and low latitude region. American Journal of Astronomy and Astrophysics 2014; 2(6): 61-65.
14. Deminov MG, Deminova GF. Geomagnetic activity that corresponds to the median of the F2- layer critical frequency at various latitudes. Geomagnetizm and Aeronomy 2016; 56: 572-576.
15. Das AC, Rajaram G, Rastogi RG. Effects on foF2 of daytime and nighttime sudden commencement storms. J Geomagnetic Geoelectric 1973; 25: 349-362.
16. Yadav R, Gwal AK. Comparative study of high and mid latitude foF2 during low solar activity, International Journal of Innovative Research in Science. Engineering and Technology 2016; 5: 289-293.
17. Tulunay YK, Sayers J. Characteristics of mid-latitude trough as determined by the electron density experiments on Ariel-3. J Atmosph Terr Phys 1971; 33: 1737-1761.
18. Chen GX, Xu WY, Wei ZG, Ahn BH, Kamide Y. Auroral Electrojet Oval. Earth Planets Space 2003; 55: 255-216.
19. Feichter E, Leitinger R. A 22-year cycle in the F layer ionization of the ionosphere. Ann Geophys 1977; 15: 1015-1027.
20. Hao YQ, Shi H, Xiao Z, Zhang DH. Weak ionization of the global ionosphere in solar cycle 24. Ann Geophys 2014; 32: 809-816.
21. Carbary JF. A Kp-based model of auroral boundaries. Space Weather 2005; 3: doi:10.1029/2005SW000162.
22. Xiong C, Lüh H, Wang H, Johnsen MG. Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures-Part 1. Ann Geophys 2014; 32: 609–622.
23. Kamide Y, Rostoker G. The spatial relationship of field-aligned currents and auroral electrojets to the distribution of nightside auroras. Journal of Geophysical Research 1977; 82: 5589–5608.
24. Kamide Y. The relationship between field-aligned currents and the auroral electrojets. Space Science Reviews 1982; 31: 127-243.
25. Tulunay YK. Global electron density distributions from the Ariel 4 satellite at mid-latitudes during quiet magnetic periods. J Atmosph Terr Phys 1973; 35: 233-254.
26. Rishbeth H. F-region storms and thermospheric circulation. J Atmos Terr Phys 1975; 37: 1055-1064.
27. Hernandez G, Roble RG. Observations of large scale thermospheric waves during geomagnetic storms. J Geophys Res 1978; 83: 5531-5538.