Validation of Regional Geoid Models for Saudi Arabia Using GPS/Levelling Data and GOCE Models

To meet increased demands in mapping, surveying, geodesy, and large infrastructure projects, an accurate national geoid model for Saudi Arabia is required to transform ellipsoid heights to orthometric heights. The lack of data and the nature of the topography make the computation of a geoid model in Saudi Arabia a difficult task. Two regional geoids were developed for the Kingdom of Saudi Arabia (KSA): (1) the KSA geoid developed by the General Directorate of Survey (GDS); and (2) a geoid developed by the Ministry of Municipality and Rural Affairs (MOMRA). The KSA model was developed using a remove and restore technique and over 5,000 observations of Global Positioning System (GPS) ellipsoidal heights on leveling benchmarks (GPS/BM). The MOMRA geoid was estimated from 861GPS/Levelling with a kriging approach. A GPS/Levelling test campaign (T campaign) was carried out in 2010 by re-observing about 391 BM stations common to the two geoid models. The two geoid models are first compared against each other and EGM2008 at the 391 BM stations from the T campaign. The absolute differences between models may reach several meters, whereas the standard deviation of the differences ranges between 0.5 and 1.5 m. Analysis revealed that KSA and MOMRA geoids seem not to coincide. Both are biased (means of 0.46 m) and highly scattered (standard deviation is ±0.72 m). Next, geoid models developed using GOCE satellite data are used to validate the T campaign data.