9:15 AM - 9:30 AM
[G02-3-04] DRUKGEOID15: The new geoid of Bhutan
In this research we present a new regional geoid for Bhutan, a land-locked country in the Himalayas. For this mountainous area only few terrestrial gravity data are available which can explain the metre level differences for this region between two recent global geopotential models: EGM2008 and EIGEN-6C4. To improve this situation, a new terrestrial gravity campaign was performed from November 2014 to May 2015. In total 255 new gravity points were observed together with their coordinates using GPS using two SCINTREX CG5 gravimeters.
Using the standard remove and restore technique, together with the residual terrain correction a new regional geoid, called DRUKGEOID15, was computed. EIGEN-6C4 together with the Shuttle Radar Topography Mission (STRM) digital terrain model a smooth residual gravity field was obtained in the remove step. Using standard least-squares collocation, this was converted into a residual height anomaly field after which the effect of EGM2008 and the terrain model on the height anomalies were restored. The height of the mountains can reach five kilometres which causes the height anomaly to geoid corrections to reach values of a few metres. Furthermore, we demonstrate that the height anomaly to geoid corrections provided by the EGM2008 model differ up to one metre with our more refined computed values following the method of Flury and Rummel (2009). Finally, we present a comparison of our geoid with orthometric heights observed at benchmarks that also were observed with GPS, demonstrating the improved accuracy of the new regional geoid compared to EGM2008 and EIGEN-6C4.
Using the standard remove and restore technique, together with the residual terrain correction a new regional geoid, called DRUKGEOID15, was computed. EIGEN-6C4 together with the Shuttle Radar Topography Mission (STRM) digital terrain model a smooth residual gravity field was obtained in the remove step. Using standard least-squares collocation, this was converted into a residual height anomaly field after which the effect of EGM2008 and the terrain model on the height anomalies were restored. The height of the mountains can reach five kilometres which causes the height anomaly to geoid corrections to reach values of a few metres. Furthermore, we demonstrate that the height anomaly to geoid corrections provided by the EGM2008 model differ up to one metre with our more refined computed values following the method of Flury and Rummel (2009). Finally, we present a comparison of our geoid with orthometric heights observed at benchmarks that also were observed with GPS, demonstrating the improved accuracy of the new regional geoid compared to EGM2008 and EIGEN-6C4.