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Continuous GPS Time Series Data Analysis in Sumatera; Case of Study: Continuous Data SuGAR (Sumatran GPS Array) 2004-2007 Leila Hanief, Sarah; Meilano, Irwan; Darmawan Wijaya, Dudy
Indonesian Journal of Geospatial Vol 1, No 2 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4659.033 KB)

Abstract. In each GPS time series data, there are signals which exist and affect the result that has been received, which is called noise. Those noise components will form certain pattern in time series. Basically, time series has periodic component which commonly not being able to be detected directly. To detect which periodic component that dominantly affect the time series, there is a way which is called spectral analysis. With acknowledge periodic component in a time series, we can know the characteristic of the time series and then we can determine how many parameters will be needed to do curve fitting. There are two approximations in fitting, it is either linear fitting only or linear fitting with including periodic component. As a comparison between these two methods, we need to be estimate displacements velocity rate in a year. From the analysis that has been done, the result is that the biggest difference of displacements velocity rate between these two methods is 3.7 milimeters per year.Keywords: displacements velocity rate, fitting, periodic component, spectral analysis, time series.

Ketelitian Posisi Pengamatan GNSS Metode Precise Point Positioning dan Metode Penentuan Posisi Relatif Azis, Rasyad Al; Suhandri, H. F.; Wijaya, Dudy Darmawan
Indonesian Journal of Geospatial Vol 5, No 2 (2018)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (739.951 KB)

Precise Point Positioning (PPP) adalah metode penentuan posisimenggunakan GNSS yang merupakan pengembangan dari metode penentuanposisi absolut. Penentuan posisi menggunakan GNSS yang sering digunakanuntuk memperoleh posisi teliti adalah metode penentuan posisi relatif. Metoderelatif sangat bergantung pada titik referensi. Hal tersebut menyebabkan metodePPP dapat menjadi alternatif karena hanya membutuhkan satu receiver tanpa adaketerkaitan dengan titik referensi. Maka dari itu, studi ini dimaksudkan untukmengetahui seberapa jauh ketelitian metode PPP terhadap metode relatif yangdianggap teliti. Pengamatan dilakukan pada dua buah titik dengan jarak kira-kira8.5 km. Berdasarkan uji coba yang dilakukan, PPP dapat mendekati ketelitianmetode relatif dengan pengamatan minimal selama 6 jam dan menggunakan dataorbit teliti IGS Final.

SPATIO-TEMPORAL CHARACTERISTICS OF SEA LEVEL ANOMALY IN THE INDONESIAN WATER Sarsito, Dina Anggreni; Wijaya, Dudy Darmawan; Trihantoro, Nur Fajar; Fathulhuda, Muhammad Syahrullah; Pradipta, Dhota
GEOMATIKA Vol 25, No 2 (2019)
Publisher : Badan Informasi Geospasial in Partnership with MAPIN

Indonesia is an archipelago state lies between Indian and Pacific Oceans at the South East Asia region. Its unique geomorphological and geographical setting affect variabilities of instantaneous sea surface height (ISSH) concering to one of the sea reference surface i.e mean sea surface height (MSSH). The differences between both heights, known as sea level anomaly (SLA), can be recognized as one of the parameter that describes the dynamic phenomena of the ocean. We investigated the Spatiotemporal characteristics of long-term SLA in this research based on 30 years of sea-level data derived from the multi-mission of satellite Altimetry (Topex/Poseidon, Jason-1, Jason-2 and Jason-3). The Spatiotemporal of SLA characteristics in Indonesian waters indicate substantial variations due to the influences of geographical location, bathymetric depth, and seasonal patterns. The SLA rate in the Indonesian region provides values that vary between 3.4 mm/yr to 5.3 mm/yr that higher than 3.2 mm/yr global SLA rate. The impact caused by the phenomenon needs to be taken into account given the vulnerability and disaster that could endanger the islands and coastal area in Indonesia.

pyGABEUR-ITB: A FREE SOFTWARE FOR ADJUSTMENT OF RELATIVE GRAVIMETER DATA Wijaya, Dudy Darmawan; Muhamad, Norman Arif; Prijatna, Kosasih; Sadarviana, Vera; Sarsito, Dina A.; Pahlevi, Arisauna; Variandy, Erfan D.; Putra, Widy
GEOMATIKA Vol 25, No 2 (2019)
Publisher : Badan Informasi Geospasial in Partnership with MAPIN

pyGABEUR-ITB (Python GayaBEUrat Relatif â€“ Institut Teknologi Bandung) is a free and interactive software for adjustment of relative gravimeter data, developed based on Python programming language. pyGABEUR-ITB can adjust relative gravity measurements and provide reliable estimates for correcting instrumentâ€™s systematic errors, such as gravimeter drift. Furthermore, pyGABEUR-ITB can also detect possible outliers in the observations using the t-criterion method. Since pyGABEUR-ITB is using the weighted constraint adjustment, at least one fixed station is required accordingly. Relative gravimeter data around Palu-Donggala area (Central Sulawesi) observed by Center for Geodesy Control Networks and Geodynamics, Geospatial Information Agency, were used to test the performance of pyGABEUR-ITB. The processing results were then compared against those calculated using GRAVNET software. The comparisons show that both pyGABEUR-ITB and GRAVNET softwares statistically provide simillar results, with the total RMS value of about 5 mGal. In term of computerâ€™s requirement, pyGABEUR-ITB can be excecuted under a computer with the following minimal requirements: x64 CPU, 1 GB memory and WINDOWS 7 OS. Finally, it is important to mention that pyGABEUR-ITB is recently suited to process the data from the gravimeter that adopts the principle of vertical spring balance. In the near future, pyGABEUR-ITB will be extended to be able to automatically adapt to various observation principles.

PETA TIGA DIMENSI (3D) CITYGML UNTUK SIMULASI ALIRAN ANGIN MENGGUNAKAN OPENFOAM Izzaty, Ghalizha Zahra; Suwardhi, Deni; Windupranata, Wiwin; Harto, Agung Budi; Wijaya, Dudy Darmawan; Murtiyoso, Arnadi; Soeksmantono, Budhy
MAJALAH ILMIAH GLOBE Vol 23, No 1 (2021)
Publisher : Badan Informasi Geospasial

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24895/MIG.2021.23-1.1260

CityGML merupakan model data yang bersifat terbuka untuk memodelkan wilayah perkotaan maupun lanskap secara 3D. Dari lima tingkat perincian/Level of Detail (LOD) pada CityGML, LOD1 dan LOD2 menjadi tingkat perincian yang penting karena dimilikinya informasi mengenai struktur atap bangunan yang merupakan syarat data dalam pelaksanaan aplikasi seperti perencanaan detail maupun penataan lingkungan dan bangunan. Dalam mendukung perencanaan dan pengembangan perkotaan dan lanskap yang berkelanjutan, pengetahuan mengenai efek aliran angin di sekitar bangunan menjadi hal yang penting dalam menyelesaikan permasalahan perkotaan yang berkaitan dengan aliran angin. Integrasi model 3D CityGML dengan perangkat lunak simulasi Computational Fluid Dynamics (CFD) OpenFOAM dapat memberikan visualisasi dan informasi mengenai aliran angin di perkotaan dengan lebih baik. Makalah ini mempunyai tujuan untuk membangun dan memvalidasi model 3D CityGML LOD1 lanskap dari data DSM, DTM, dan tutupan lahan serta menerapkan simulasi aliran angin pada model 3D CityGML LOD1 lanskap yang telah dibangun dengan menggunakan perangkat lunak OpenFOAM. Model 3D LOD1 direkonstruksi dari data Digital Surface Model dan peta vektor 2D Kampus ITB Jatinangor, sedangkan bentuk atap pada model 3D LOD2 dihasilkan dari pengamatan stereo fotogrametri. Hasil simulasi aliran angin menunjukkan pengaruh model 3D LOD1 terhadap aliran angin berupa perubahan arah dan kecepatan, serta geometri model 3D LOD1 bangunan dan pohon menyebabkan informasi aliran angin menjadi kurang akurat di sekitar atap bangunan dan di sekeliling pohon. Hal ini dapat diperbaiki dengan menambah tingkat perincian model yang digunakan menjadi LOD2.Â

Quality control in GNSS reflectometry method for tide observations Agung Syetiawan; Dudy Darmawan Wijaya; Irwan Meilano
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 6: December 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i6.21670

Recently, the reflected signals from global navigation satellite systems (GNSS) have been utilized to observe coastal tides, and it has been found that this method provides promising results. Although this method is promising, there remain problems related to accuracy of the observed tides. The purpose of this study was to improve the accuracy by employing an optimal spectral method in the quality control scheme. The quality control process is carried out by setting parameters to achieve the best possible frequency correlated with sea levels such as estimation of the noise frequency range, frequency amplitude power selection, and selection of peak frequency to noise ratio. The results using the data at Morotai station showed that the amplitude power less than 5 comes from low-frequency signals and hence it is an indicator that the Lomb-Scargle periodogram (LSP) fails to determine the dominant frequency. In addition, the result of the peak frequency to noise ratio shows a value of 2.7, meaning that the peak frequency of the LSP signal is at least 2.7 times greater than the signal noise. Quality control sensitivity settings are very effective in determining the reflectors height coming from the sea level. The periodogram visualization can be used to decide which LSP is significant.

Continuous GPS Time Series Data Analysis in Sumatera; Case of Study: Continuous Data SuGAR (Sumatran GPS Array) 2004-2007 Sarah Leila Hanief; Irwan Meilano; Dudy Darmawan Wijaya
Indonesian Journal of Geospatial Vol 1 No 2 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract. In each GPS time series data, there are signals which exist and affect the result that has been received, which is called noise. Those noise components will form certain pattern in time series. Basically, time series has periodic component which commonly not being able to be detected directly. To detect which periodic component that dominantly affect the time series, there is a way which is called spectral analysis. With acknowledge periodic component in a time series, we can know the characteristic of the time series and then we can determine how many parameters will be needed to do curve fitting. There are two approximations in fitting, it is either linear fitting only or linear fitting with including periodic component. As a comparison between these two methods, we need to be estimate displacements velocity rate in a year. From the analysis that has been done, the result is that the biggest difference of displacements velocity rate between these two methods is 3.7 milimeters per year.Keywords: displacements velocity rate, fitting, periodic component, spectral analysis, time series.

Ketelitian Posisi Pengamatan GNSS Metode Precise Point Positioning dan Metode Penentuan Posisi Relatif Rasyad Al Azis; H. F. Suhandri; Dudy Darmawan Wijaya
Indonesian Journal of Geospatial Vol 7 No 2 (2018)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar

Precise Point Positioning (PPP) adalah metode penentuan posisimenggunakan GNSS yang merupakan pengembangan dari metode penentuanposisi absolut. Penentuan posisi menggunakan GNSS yang sering digunakanuntuk memperoleh posisi teliti adalah metode penentuan posisi relatif. Metoderelatif sangat bergantung pada titik referensi. Hal tersebut menyebabkan metodePPP dapat menjadi alternatif karena hanya membutuhkan satu receiver tanpa adaketerkaitan dengan titik referensi. Maka dari itu, studi ini dimaksudkan untukmengetahui seberapa jauh ketelitian metode PPP terhadap metode relatif yangdianggap teliti. Pengamatan dilakukan pada dua buah titik dengan jarak kira-kira8.5 km. Berdasarkan uji coba yang dilakukan, PPP dapat mendekati ketelitianmetode relatif dengan pengamatan minimal selama 6 jam dan menggunakan dataorbit teliti IGS Final.

VARIASI DIURNAL UAP AIR DI LAPISAN TROPOSFER BAWAH SAAT MADDEN JULIAN OSCILLATION FASE AKTIF MEMASUKI KAWASAN BARAT INDONESIA BERBASIS ANALISIS DATA GPS (DIURNAL VARIATION OF LOW LEVEL MOISTURE WHEN THE ACTIVE PHASE OF MADDEN JULIAN OSCILLATION ENTERING AREA OF WESTERN INDONESIA BASED ON GPS DATA ANALYSIS) Aries Kristianto; Tri Wahyu Hadi; Dudy Darmawan Wijaya
Jurnal Sains Dirgantara Vol 13, No 1 (2015)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1298.139 KB)

Uap air di lapisan troposfer bawah (Low-level Moisture/LLM) berperan dalam pertumbuhan awan hujan. Teknologi Global Positioning System (GPS) mampu mengekstraksi uap air LLM dengan menerapkan metode kombinasi selisih uap air total hasil ekstrasi groundbased GPS dengan Precipitable Water Vapor (PWV) di lapisan troposfer atas ECMWF. Variasi diurnal LLM berbasis data GPS di beberapa kawasan yang ada di bagian barat Indonesia, yaitu wilayah Jawa bagian Barat dianalisis terutama saat fase aktif Madden Julian Oscillation (MJO) sebagai salah satu variabilitas dominan yang sangat penting di daerah tropis. Kejadian MJO November 2009 di wilayah Jawa bagian Barat memberikan dampak terhadap variasi harian LLM, dimana anomali hariannya meningkat seiring dengan menurunnya anomali OLR saat MJO onset, dan menurun saat pasca MJO. Di bagian utara menunjukkan konsentrasi LLM menurun dari barat-timur, sedangkan di bagian selatan konsentrasinya meningkat. Variasi dari utara-selatan menunjukkan konsentrasi LLM yang cenderung berubah-ubah, sementara di bagian timur peningkatan uap air ke arah selatan sesuai dengan analisis vektor angin. Variasi diurnal LLM November 2009 saat fase MJO aktif secara umum konsentrasinya lebih tinggi dibandingkan pra dan pasca MJO. Dari analisis indeks konvektif citra satelit MTSAT IR1 juga menunjukkan LLM saat MJO berkaitan dengan aktivitas konvektif, baik pada periode pra-MJO, saat onset, aktif hingga pasca MJO.Kata Kunci: LLM,GPS, MJO, OLR

Pemodelan Pasut di Indonesia Timur Menggunakan Data Asimilasi dari Altimetri, Stasiun Pasut, dan Model Hidrodinamika Misfallah Nurhayati; Dudy Darmawan Wijaya
Jurnal Inotera Vol. 9 No. 1 (2024): January-June 2024
Publisher : LPPM Politeknik Aceh Selatan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31572/inotera.Vol9.Iss1.2024.ID346

Tides play a crucial role in various coastal and marine activities. Despite numerous tidal models developed in Indonesia, modeling tides in shallow waters with complex topographies remains challenging, particularly in the Eastern Indonesian Sea. This study aims to develop a high-accuracy tidal model for Eastern Indonesian sea using data assimilation techniques integrating observational data and ocean dynamics model. The study tested various scenarios, including different numbers of tide gauge observations, representers, and decorrelation length values in dynamic equations. By assimilating data from altimetry, tide gauges, and hydrodynamic models, significant improvements in model accuracy were achieved. Results show that of the 11 validator tide stations, while the rest stations have the predicted RMS values below 16 cm, and seven stations have the predicted RMS values below 9 cm. These findings highlight the potential use of assimilation technique for accurate tidal predictions in shallow waters with complex topographies, enhancing the safety and efficiency of coastal and marine activities in Eastern Indonesia.

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