Farklı Şiddetlerde Meydana Gelen Güneş Aktivitesinin GPS-PPP Doğruluğu Üzerindeki Etkisinin Bölgesel olarak Araştırılması

Öz

Son yıllarda GNSS (Global Navigation Satellite System) topluluğu içerisinde, (Hassas Nokta Konumlama (Precise Point Positioning, PPP) yöntemi oldukça ilgi çekici bir konu haline gelmiştir. PPP tekniği ile, herhangi bir referans istasyonuna ihtiyaç duymadan yalnızca tek bir alıcı kullanarak yüksek konum doğruluğuna erişmek mümkündür. Ancak birçok hata kaynağı PPP hassasiyetini doğrudan ya da dolaylı olarak etkilemektedir. Bu çalışmada, Güneş’te meydana gelen farklı şiddetlerdeki aktivitelerin GPS-PPP doğruluğu üzerindeki etkisi bölgesel olarak araştırılmıştır. Bu amaç doğrultusunda kutup, orta ve ekvatoral enlem bölgesinden olmak üzere Uluslararası GNSS Servisi (IGS) ağına ait üç istasyon seçilerek güneşte meydana gelen aktivite şiddetine göre GPS-PPP doğruluğundaki değişim izlenmiştir. Yaklaşık 11 yıllık güneş döngüsü dikkate alınarak 2000-2018 yılları arasındaki minimum, orta ve maksimum aktivite dönemlerine ait 60’ar günlük GPS verileri kullanılmıştır. GPS verileri, Güneşte meydana gelen aktivite değişimini tam olarak yansıtabilmesi için gündüz vaktine denk gelen saat 10:00-18:00 aralığındaki 8 saatlik kısa veri oturumlarına bölünmüştür. Elde edilen tüm veri setleri NASA/JPL'nin GIPSY/OASIS II v6.4 yazılımının Hassas Nokta Konumlama (PPP) modülü kullanılarak analiz edilmiştir. Söz konusu üç farklı aktivite dönemi ve üç farklı bölgede gözlenen GPS-PPP doğruluğundaki değişimler karşılaştırılmıştır. Karşılaştırmalar sonucunda, güneşte meydana gelen patlamalar arttıkça GPS-PPP doğruluğunun azaldığı ve bu durumdan en fazla ekvatoral enlem bölgesinin etkilendiği gözlenmiştir.

Anahtar Kelimeler

• GPS
• PPP
• Konum doğruluğu
• Güneş aktivitesi
• Güneş patlamaları

A Regional Investigation of the Effect of Solar Activity of Different Intensities on GPS-PPP Accuracy

Öz

In recent years, Precise Point Positioning (PPP) has become a very interesting topic within the GNSS (Global Navigation Satellite System) community. With the PPP technique, it is possible to achieve high position accuracy using only a single receiver without the need for any reference station. However, many sources of error directly or indirectly affect PPP accuracy. In this study, the impact of different intensities of solar activity on GPS-PPP accuracy was investigated regionally. For this purpose, three stations belonging to the International GNSS Service (IGS) network were selected from the polar, mid-latitude and equatorial latitudes and the change in GPS-PPP accuracy was monitored according to the intensity of solar activity. Considering the solar cycle period of approximately 11 years, 60 days of GPS data for the minimum, medium and maximum activity periods between 2000-2018 were used. The GPS data were divided into short 8-hour data sessions between 10:00-18:00, which coincides with the daytime, to fully reflect the changes in solar activity. All data sets were analyzed using the Precision Point Positioning (PPP) module of NASA/JPL's GIPSY/OASIS II v6.4 software. The changes in GPS-PPP accuracy observed during the three different periods of activity and in three regions were compared. As a result of the comparisons, it was observed that the GPS-PPP accuracy decreases as the intensity of solar activity increases, with the equatorial latitude region being most affected.

Anahtar Kelimeler

• GPS
• PPP
• Positioning accuracy
• Solar activity
• Solar flares

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