Airborne gravity method for high-resolution geoid model in Indonesia held in Sumatera Island using Lacoste & Romberg Air-Sea Gravity Meter S-130 and Trimble R9S GNSS installed in the cessna grand caravan type C208B. Flight altitude ranging from 3000 to 4000 meters and the aircraft speed is 277 km/h. Processing GNSS are using differential processing which is tied to SRGI2013 with a standard deviation tolerance <7 cm in high position and 90% data fix. The gravity raw data (LCR file) is filtered using the lowpass filtering filter mode with the weight function blackman window, the filter window used is 150-seconds. From crossover analysis, some cross over misfit relatively large difference with more than ±20 mGal difference, the average and standard deviation of crossover misfit were -0.0023 mGal and 9.0214 mGal respectively. The result of spectral analysis, airborne gravity signal has minimum 10 km of wavelength while the EGM2008 degree 2190 has minimum 18 km of wavelength.
Quasigeoid lokal pulau Bali di definisikan menggunakan persamaan Hotine. Data yang digunakan kombinasi data gangguan gayaberat hasil pengukuran terestris, gayaberat laut DTU17, EGM2008 derajat 360 dan SRTM15 dengan berbagai variasi jarak spheris diuji untuk menghasil quasigeoid teliti. Variasi jarak spheris yang digunakan sebesar 0,1˚,
Abstract. Nowadays satellite altimetry has become an advanced instrument to observe many natural physical phenomena, such as sea-level rise, ocean circulation, water mass changes, and marine gravity anomaly. The use of satellite altimetry data to compute marine gravity anomaly provides good results and costs relatively low. Those advantages make geodesists utilize this method as an alternative in geoid determination, especially over the seas. Several sets of satellite altimetry data from Cryosat 2, Jason 1 phase C, Geosat and ERS1 were used to compute gravity anomaly over the surrounding waters of Kalimantan and Sulawesi Island in Indonesia. The study area spans between -7 0 -7 0 N and 108 0 -127 0 E with a spatial resolution of 1'x1'. In the preprocessing step, the altimetry data especially Geosat and ERS1, were retracked to reduce errors due to the land influence. The main computation step was done by using two different methods, least square collocation (LSC) and Inverse Vening-Meinesz (IVM). The computed gravity anomaly models then assessed with the in-situ marine gravity data from the National Geophysical Data Center (NGDC). The best model in term of RMS error is the 10 km Gaussian filtered LSC with an RMS error of 15.042 mgal. The least accurate model is the non-filtered IVM with an RMS of 16.704 mgal.
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