QUALITY INVESTIGATION OF GRAVITY DATA FROM AIRBORNE GRAVIMETRY MEASUREMENT USING DOWNWARD CONTINUATION PROCESS IN KALIMANTAN REGION
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 gravi...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/43960 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | 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
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