Modeling Gravity Gradients from Surface Gravity Anomaly Data

Yıl 2024, Cilt: 26 Sayı: 78, 470 - 480

Sibel Uzun

Öz

Gravity gradients are useful to characterize near mass anomalies since they are much more sensitive to short wavelength anomalies than gravitational accelerations. Estimating gravity gradients from surface gravity data is based on numerical implementations of solutions to geodetic boundary value problem for determination of disturbing potential. One of methods to solve this problem is least-squares collocation which is basically based on data and a defined covariance function. This study deals with estimating gravity gradient tensor components from along track surface gravity anomaly data. The Least-Squares Collocation solution is based on a stationary local covariance function defined for the disturbing potential which allows upward continuation of the observations to a desired altitude. The modeling method is evaluated in using Earth Gravitational Model 2008(EGM2008) and real airborne gravity gradiometry data collected over Southern Texas, Oklahoma region. The results show that modeled gravity gradients estimated in both on the ground and at a certain altitude have basically good agreement with EGM08 gradients. Modeled gradients including horizontal components in the east-west direction exhibit some discrepancies in comparison to the airborne gradiometry data, which may be attributed to some measurement errors in the gradient data.

Anahtar Kelimeler

Least-squares collocation, Covariance matrix, Gravity gradient tensor

Yüzey Gravite Anomali Verilerinden Gravite Gradyentlerin Modellenmesi

Öz

Gravite gradyentleri kısa dalga boylu anomalilere yerçekimi ivmelerinden daha fazla duyarlı oldukları için yüzeye yakın kütle anomalilerini belirlemede faydalıdırlar. Gravite Gradyentlerinin yüzey gravite anomalilerinden kestirimi bozucu potansiyelin belirlenmesinde jeodezik sınır değer problemi çözümlerinin sayısal uygulamalarına dayanmaktadır. Bu problemi çözmenin yöntemlerinden birisi temel olarak veriye ve tanımlanan bir kovaryans fonksiyonuna dayanan En Küçük Kareler Kollokasyonudur. Bu çalışma bir profil boyunca verilen yüzey gravite anomali verilerinden gravite gradyent tensör elemanlarının kestirimi ile ilgilidir. En küçük kareler kollokasyon çözümü gözlemlerin istenen bir yüksekliğe yukarı uzanımına imkan veren bozucu potansiyel için tanımlanmış bir durağan yerel kovaryans fonksiyonuna dayanır. Modelleme yöntemi Yer Gravite Modeli 2008 ve Güney Teksas Oklahoma bölgesi üzerinde toplanmış gerçek havadan gravite gradyometri verileri kullanılarak değerlendirilmiştir. Sonuçlar, hem yeryüzü üzerinde hem de belirli bir yükseklikte kestirilen modellenmiş gravite gradyentlerinin EGM08 gradyentleri ile uyumlu olduğunu göstermektedir. Doğu-batı yönündeki yatay bileşenleri içeren modellenmiş gradyentler, havadan gradyometre verilerine kıyasla bazı uyumsuzluklar göstermektedir; bu durum gradyent verilerindeki bazı ölçüm hatalarına bağlı olabilir.

Anahtar Kelimeler

Ek küçük kareler kollokasyon, Kovaryans matris, Gravite gradyent tensor

Kaynakça

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