Pengaruh Densitas Topografi Terhadap Ketelitian Model Geoid: Studi kasus Pulau Sulawesi

Leni Sophia Heliani; Hendra Noviantara

doi:10.22146/jgise.102122

Pengaruh Densitas Topografi Terhadap Ketelitian Model Geoid: Studi kasus Pulau Sulawesi

https://doi.org/10.22146/jgise.102122

Leni Sophia Heliani^(1*), Hendra Noviantara⁽²⁾

(1) Department of geodetic Engineering, Universitas Gadjah Mada
(2) Department of geodetic Engineering, Universitas Gadjah Mada
(*) Corresponding Author

Abstract

Penentuan model geoid teliti penting untuk mendapatkan tinggi ortometrik dari tinggi Global Navigation Satellite System (GNSS). Salah satu faktor yang mempengaruhi ketelitian model geoid adalah densitas topografi. Umumnya, penentuan model geoid pada formula Stokes menggunakan densitas massa standar sebesar 2670 kg/m³. Namun, densitas topografi sesungguhnya bervariasi. Saat ini, tersedia model densitas global, salah satunya yang dibuat University of New Brunswick (UNB) dengan resolusi 30”. Penelitian ini bertujuan untuk menganalisis pengaruh penggunaan densitas topografi dari densitas standar dan model global UNB terhadap ketelitian model geoid yang dihasilkan. Pemodelan geoid menggunakan metode Kungliga Tekniska Högskolan (KTH), dengan studi kasus Pulau Sulawesi, salah satu pulau yang memiliki variasi topografi yang sangat tinggi. Hasil validasi menggunakan data co-site GNSS-levelling menunjukan perubahan ketelitian yang tidak signifikan pada level milimeter, untuk geoid menggunakan densitas standar (N_Standar) dan model global UNB (N_UNB)_.Nilai standar deviasi dan RMS dari model N_Standarsebesar 12,65 cm. Sedangkan nilai standar deviasi dan RMS dari model N_UNB sebesar 12,58 cm dan 12,59 cm. Hal ini dikarenakan titik-titik validasi terletak pada lokasi dengan topografi yang tidak terlalu bervariasi. Selanjutnya, dilakukan pendetailan hitung perbedaan nilai geoid N_Standar dan N_UNB,diperoleh selisih antara -20 s.d. 30 cm di wilayah pegunungan. Perbedaan dalam level desimeter ini menunjukan efek yang signifikan dari densitas topografi terhadap ketelitian geoid, sehingga tidak bisa diabaikan, terutama untuk wilayah dengan variasi topografi yang tinggi.

Keywords

Geoid, Stokes Modification, KTH, Sulawesi Island, density variation

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DOI: https://doi.org/10.22146/jgise.102122