TUSAGA-Aktif Noktaları Kullanılarak Bölgesel TEC Değerinin Belirlenmesi

Yıl 2020, , 250 - 266, 20.05.2020

Sercan Bülbül

https://doi.org/10.35414/akufemubid.646324

Öz

GNSS (Global Navigation Satellite Systems - Küresel Navigasyon Uydu Sistemleri) sinyalleri alıcıya ulaşıncaya kadar birçok tabakadan geçmektedir. Bu tabakalardan iyonosfer, günün saatine, mevsimlere, coğrafi konuma ve güneşteki patlamalara bağlı olarak sürekli değişim halindedir. İyonosferin karakteristik özelliği TEC (Total electron content - Toplam Elektron Yoğunluğu) ile belirlenmektedir. TEC, GNSS ölçülerini direk olarak etkilemez fakat üretilen kombinasyonlarla kestirilebilir. Bu çalışmada Türkiye’ nin kuzey doğusunda bulunan 13 TUSAGA-AKTİF istasyonu ile 12 IGS (The International GNSS Service- Uluslararası GNSS Servisi) istasyonunun bulunduğu toplam 25 istasyon seçilmiş ve değerlendirilmiştir. Değerlendirmede Bernese v5.2 Bilimsel GNSS yazılımı kullanılmıştır. 2009 yılından 2015 yılına kadar TEC değerleri ikişer saat aralıklarla hesaplanmıştır. Tek Tabaka Modelinin kullanıldığı çalışmada GNSS ölçülerinden elde edilen TEC değerleri, CODE(The Centre for Orbit Determination in Europe -Avrupa yörünge belirleme merkezi), ESA (The European Space Agency -Avrupa Uzay Ajansı), Jet Propulsion Laboratory (JPL) tarafından yayınlanan global iyonosfer haritası (GIM-TEC) ve uluslararası iyonosfer referans modeli programından elde edilen TEC (IRI TEC) değerleriyle karşılaştırılmıştır. Karşılaştırma sonucunda bölgesel (RIM) TEC değerleri ile gobal (CODE, ESA, JPL) TEC değerleri arasında büyük oranda benzerlik olduğu ve aralarındaki farkın en fazla 2,58 TECU olduğu görülmektedir. IRI’ den elde edilen TEC değerleri bu dört değere nazaran daha düşüktür ve bölgesel TEC (RIM) değerleri ile aralarındaki fark 15.67 TECU (TEC unit)' ya kadar ulaşmaktadır.

Anahtar Kelimeler

Bernese, GNSS, TEC, TUSAGA-Aktif, GIM, İyonosfer

Determination of Regional TEC Values using CORS-Tr Stations

Öz

GNSS(Global Navigation Satellite Systems) signals pass through various layers of atmosphere until they reach the receiver on earth. the ionosphere, one of these layers, is constantly changing depending on the time of day, seasons, geographical location and explosions in the sun. One of the most important parameters expressing the ionosphere is TEC (Total electron content). GNSS signals affected by the variable structure of the ionosphere are proportional to TEC. The determination of TEC exchange is important for the modeling of the ionosphere. The TEC value cannot be obtained directly from GNSS measurements, but can be estimated by the combinations produced. 13 CORS-Tr stations which are located at northeast of Turkey and 12 IGS stations were used. At process, Bernese GNSS software was used. From 2009 to 2015, TEC values were calculated in two hour intervals. The TEC values obtained from GNSS measurements were compared with Global Ionesphere Maps published by CODE, ESA, JPL and IRI -2012. As a result of the comparison, RIM-TEC values and CODE, ESA, JPL TEC values are similar and there is a maximum difference of 2.58 TECU. TEC values obtained from IRI-2012 are lower than these four values and the difference between RIM-TEC values and IRI-2012 TEC values are up to 15.67 TECU.

Anahtar Kelimeler

Bernese, GIM, GNSS, TEC, CORS-Tr, Ionesphere

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