QUALITY INVESTIGATION OF GRAVITY DATA FROM AIRBORNE GRAVIMETRY MEASUREMENT USING DOWNWARD CONTINUATION PROCESS IN KALIMANTAN REGION

• Main Author: Ilfiyaningrum, Alfita
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/43960
• Institution: Institut Teknologi Bandung

Indonesia needs a high-quality geoid as a vertical measurement reference. Geoid is built on the geoid undulation value of the reference ellipsoid. The calculation of the undulation value uses the basic principle of the Stokes formulation which requires gravity data on the geoid surface. The gravity data must be of good quality, which has high accuracy and resolution. Airborne gravimetry can produce data that has high-density. However, acquisitions made in the air, not sticking to objects became a problem in this study. So we need a method to reduce data to the reference surface called downward continuation. In this research, gravity data quality control is carried out before and after the downward process using the fast-fourier transform method. This method performs downward continuation in the frequency domain of data, from the average flight height to the reference surface, the ellipsoid WGS1984. From the quality test results before DWC, the cross-over sample values were found in the range of 0-15 mgal. Two DWC methods are used, namely the RCR and non-RCR steps. RCR is a method that involves the process of removing global and terrain contributions before DWC and adding them back after DWC. Between RCR and Non-RCR methods produce the same results both spectral content and spatial patterns. So that for the processing of gravity disturbance data in the Kalimantan region the effect of the RCR method is not dominant in the DWC results. After comparing with another results, BIG and EGM2008, They have different results. All three results differ greatly with the EGM2008 value. In testing data quality before and after DWC, all results show that DWC increased power data in the frequency domain. There is shows that the DWC process produces data with stronger signals