Comparison of Destriping Methods of GRACE Satellite for Total Water Storage Calculation in Peatland Borneo Island

GRACE satellites frequently used to calculate total water storage in terrestrial areas, including peatland. Total water storage (TWS) needed to monitor Peatland fires risk. However, processing methods need to be considered carefully. This study intends to find out the best destriping method for estimating total water storage. This study compared data from the CSR model with a maximum degree of 96, from 2002 to 2017, located in Borneo Island. The destriping method compared namely Chen P3M6, Chen P5M8, Chambers 2007, Chambers 2012, Duan, and Swenson. This study used GRAMAT toolbox developed [1]. Results shows of the 6 methods that compared, 3 unique values are produced. Chen P5M8 and Swenson method produced the same value. Chambers 2007, Chambers 2012, and Duan method also produced the same value. Only Chen P3M6 produce different results without similarities. The correlation matrix between methods shows value close to 1, means there is no significant difference between methods. This study concluded that the type of destriping method for TWS calculation in peatland aren’t significantly affecting the result

A Comparison of Geologic Structure Detection of Sumatera Island Using Goce Satellite Gravity Data and Sgg-Ugm-2 Data

GOCE gravity satellite data can be used for regional fault detection because the observation area is wide and not limited by area. In this study, GOCE satellite data is used to detect geological structures on the island of Sumatra, the results of which are used as the basis for disaster mitigation. GOCE data and SGG-UGM-2 were processed using the GOCE User Toolbox (GUT) software to produce a gravity disturbance map and a complete bouguer anomaly map. The GOCE obtained results were validated using the SGG-UGM-2 high-resolution gravity model data. The calculation results obtained that the gravity disturbance value from the GOCE data was around -140 to 200 mGal, while the value of the gravity disturbance from the SGG-UGM-2 data was around -180-300 mGal. The GOCE gravity disturbance map and the SGG-UGM-2 can detect the Subduction Trench, Mentawai Fault, and West Andaman Fault on Sumatra Island with negative values, while the Sumatran Fault Zone (SFZ) along Sumatra Island with positive values ​​in line with the presence of mountain ranges. The results of the SGG-UGM-2 data processing for the gravity disturbance are more detailed than GOCE because the SGG-UGM-2 data degree is higher than that of GOCE. GOCE complete bouguer anomaly value is around 40-560 mGal, while the value of complete bouguer anomaly SGG-UGM-2 is around 60-560 mGal. The complete bouguer anomaly maps from GOCE and SGG-UGM-2 can detect patterns from the Subduction Trench, Mentawai Fault, and West Andaman Fault but cannot clearly detect SFZ. The complete bouguer anomaly can also detect differences between oceanic and continental crust. The GOCE and the SGG-UGM-2 complete bouguer anomaly map show almost similar patterns and the ability to detect geological structures for sub and regional Sumatra Island. In addition, GOCE data detect geological structures more clearly than GRACE data

EVALUASI MODEL DATA SATELIT GRACE UNTUK ESTIMASI TOTAL SIMPANAN AIR DI WILAYAH LAHAN GAMBUT PULAU KALIMANTAN

Simpanan Air Tanah (TWS) merupakan salah satu komponen utama siklus hidrologi di permukaan bumi. Pada penelitian ini, nilai TWS diestimasi berdasarkan data gayaberat dari satelit GRACE, dengan studi kasus di wilayah lahan gambut pulau Kalimantan. Model data satelit GRACE yang digunakan ada 3 yakni CSR, GFZ, dan JPL dengan data akuisisi dari 2002 hinga 2017. Proses perhitungan menggunakan toolbox GRAMAT yang dikembangkan oleh Wei Feng dengan proses meliputi hitungan nilai Tinggi Air Rerata (EWH), reduksi efek ocean-leakage, serta analisis harmonik meliputi amplitudo, fase, dan perubahan tahunan. Dari hasil diperoleh informasi bahwa perubahan nilai EWH yang dihasilkan oleh tiap model data bernilai positif, dengan nilai berkisar antara 0.474 – 0.676 mm tiap tahunnya. Matrik korelasi antar model menunjukkan nilai korelasi di atas 0.81, hal ini berarti semua model memberikan hasil yang relatif sama. Berdasarkan nilai ketelitian dari simpangan baku maka model data  yang paling cocok untuk perhitungan simpanan air lahan gambut adalah model data JPL

Importance of Tropospheric Correction to C-band InSAR Measurements: Application in the 2018 Palu Earthquake

Long-term InSAR-based observations are prone to atmospheric delay interference. The active-phase signals emitted and recorded back by sensors during imaging are easily disturbed by the electron content in the ionospheric layer and the water vapor content in the tropospheric layer. Given that the short wavelength of the C-band used by Sentinel-1 is more sensitive to tropospheric delay than to ionospheric delay, in this work, we utilized InSAR Sentinel-1 data to observe the postseismic deformation that occurred following the 2018 Palu earthquake and to evaluate the effect of tropospheric delay on the estimated interferogram time series. The cloud computation of Looking into Continent from Space with Synthetic Aperture Radar (LiCSAR) and LiCSBAS was used to generate interferograms and analyze the time series. Here the atmospheric delay was modeled by using Generic Atmospheric Correction Online Service (GACOS) and removed from the generated interferograms. Results showed that the annual velocity and cumulative line-of-sight (LOS) displacement were refined by correcting the atmospheric delay. Specifically, by applying GACOS, the standard deviation of the generated interferograms decreased by up to 76.6%. GNSS observations were utilized to verify the improvement due to the removal of tropospheric noise. We found that LOS displacement with GACOS correction better fitted the GNSS observation than LOS displacement without GACOS correction. Therefore, atmospheric correction plays an important role in long-term InSAR-based observations, especially in avoiding any bias in the interpretation of the estimated time series

Estimasi Potensi Gempa Tektonik di Wilayah Sesar Opak Berdasarkan Data Pengamatan GPS

Yogyakarta merupakan daerah ring of fire dengan adanya wilayah-wilayah subduksi lempeng tektonik. Kondisi ini mengakibatkan tingginya potensi gempa tektonik di daerah Yogyakarta. Seperti pada tahun 2006, telah terjadi gempa tektonik dengan skala 6,3 Mw di Yogyakarta dan menimbulkan dampak negatif. Gempa ini disebabkan oleh aktivitas Sesar Opak. Berdasarkan penelitian sebelumnya, segmen patahan Sesar Opak tidak semua melepaskan energi, sehingga dimungkinkan berpotensi menimbulkan gempa tektonik besar di masa yang akan datang. Oleh karena itu, penelitian ini bertujuan untuk mengenalisis dan mengestimasi potensi gempa tektonik di sekitar wilayah Sesar Opak berdasarkan data pengamatan GPS. Penelitian ini juga mengestimasi maximum magnitude dan periode perulangan maximum magnitude tersebut. Data yang digunakan dalam penelitian ini adalah data pengamatan GPS pada titik-titik pantau Sesar Opak sejumlah 11 buah dari tahun 2016, 2017, dan 2018. Data pengamatan GPS diolah dengan perangkat lunak GAMIT/GLOBK. Data diolah dengan membagi area menjadi sebelah Timur dan sebelah Barat Sesar Opak. Selanjutnya, dilakukan perhitungan estimasi maximum magnitude dan periode perulangan maximum magnitude. Hasil dari pengolahan data GPS menunjukkan bahwa resultan kecepatan pergeseran horizontal titik pantau Timur Sesar Opak lebih besar dari pada titik pantau Barat Sesar Opak. Hal ini dapat mengindikasikan Timur Sesar Opak lebih aktif dari pada Barat Sesar Opak. Adanya pergeseran aktif ini dapat menimbulkan potensi gempat tektonik dikemudian hari. Selain itu, hasil estimasi maximum magnitude yang dapat terjadi di wilayah Sesar Opak adalah 6,5 Mw dengan periode perulangan maximum magnitude selama ± 60 tahun pada Segmen Utara dan selama ± 130 tahun pada Segmen Selatan. Namun hasil perhitungan estimasi ini masih perlu disempurnakan dengan dengan menambahkan data lain seperti seismik multitemporal

チヒョウ ジュウリョク データ エイセイ コウドケイ データ オヨビ ディジタル チケイ モデル データ ノ クミアワセ ニ ヨル インドネシア ノ ジュウリョクバ ノ ケッテイ

京都大学0048新制・課程博士博士(理学)甲第9963号理博第2624号新制||理||1337(附属図書館)UT51-2003-H384京都大学大学院理学研究科地球惑星科学専攻(主査)助教授 福田 洋一, 教授 竹本 修三, 教授 岡田 篤正学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

EVALUASI VARIAN DATA MODEL TERAIN DIGITAL DALAM PENENTUAN MODEL GEOID LOKAL Studi kasus: D.I. Yogyakarta: (Evaluation of Digital Terrain Models for Local Geoid Determination a Case Study in D.I. Yogyakarta Province, Indonesia)

Penentuan model geoid lokal teliti membutuhkan data topografi beresolusi tinggi sebagai representasi kondisi topografi. Sejak Juli 2018, Indonesia telah merilis model topografi mosaik (seamless) mencakup seluruh wilayah Indonesia dengan resolusi spasial mencapai 0,27 arcsec, yaitu DEM Nasional (DEMNAS). DEMNAS dibangun dengan mengkombinasikan berbagai sumber data RADAR serta data masspoint hasil stereo-plotting. DEMNAS diklaim dapat menggantikan penggunaan DEM SRTM maupun peta Rupa Bumi Indonesia (RBI) dalam berbagai keperluan, salah satunya dalam penentuan model geoid lokal. Akan tetapi, pemanfaatan DEMNAS dalam penentuan model geoid lokal belum diuji. Penentuan model geoid lokal pada studi ini menggunakan metode Least Square Collocation (LSC). Studi ini bertujuan untuk mengevaluasi penggunaan varian data Digital Terrain Model (DTM) DEMNAS, peta RBI skala 1:25.000, dan SRTM30_plus dalam penentuan model geoid lokal di wilayah D.I. Yogyakarta. Hasil pemodelan geoid lokal menunjukkan bahwa nilai koreksi terrain terkecil dihasilkan dari DTM SRTM30_plus yaitu sebesar 22,196 mGal, sedangkan nilai indirect effect terkecil dihasilkan dari DTM peta RBI skala 1:25.000, yaitu sebesar 0,272 m. Ketelitian tertinggi undulasi geoid lokal D.I. Yogyakarta dihasilkan dari DTM peta RBI skala 1:25.000 dengan nilai simpangan baku sebesar 0,440 m. Penelitian ini menunjukkan bahwa DTM yang paling optimal digunakan untuk pemodelan geoid lokal D.I. Yogyakarta adalah peta RBI skala 1:25.000. Namun, penggunaan DTM peta RBI skala 1:25.000, DEMNAS, dan SRTM30_plus untuk pemodelan geoid lokal menunjukkan hasil ketelitian yang tidak berbeda secara signifika

Evaluation of Combining Land and Waters Data on Local Gravimetric Geoid Modelling (Case Study : D.I. Yogyakarta Coastal Area)

Geoid is the equipotential gravity field of the earth which coincides with the undisturbed-mean sea level. Geoid used as a reference to determining height for scientific and also practical application in a region/nation. Until present, the national Indonesian geoid has not determined accurately yet, especially due to limitation of availability and various level of accuracies gravity data. Local geoid becomes one of solution to produce accurate height reference. For the case of Indonesia as archipelagic country, where the land and water always side by side, a combination of land and water area becomes a necessity. Therefore, this research aims to evaluate the effect of combination of land and water data on local geoid modelling with case study in D.I. Yogyakarta, which has been selected based on its location in the coastal region and its availability of gravity data. The local gravimetric of D.I. Yogyakarta is done by 2D-FFT technique, by combining the data of land and waters gravity data, the height data, the water’s depth and also EGM 2008 data. The local gravimetric geoid in coastal area is controlled by 4 control points. Geometric undulations in 4 control points obtained from co-sited GNSS/water pass leveling measurement. The results show that the combination of land and waters data in the computation of local gravimetric geoid increased the mean accuracy of 4 control points becomes 0.0813 m. In addition, the waters data give the positive contribution to local geoid model of D.I. Yogyakarta and also make it more representative and real than before