Terrain Effect on Geoid Determination Case Study:NW Iran Print

The main topic of this research is to investigate different gravimetric reduction in the context of precise geoid determination. Gravimetric reduction perform an essential role on precise geoid determination, particularly in rugged areas. A numerical investigation was performed in the rugged area of the Northwest Iran within the geographical boundaries 35.5> φ >39.5 and 44.5>>λ >49.5 to study gravimetric geoid solutions based on the Rudzki inversion scheme, Hеlmert’s second method of condensation, RTM, and the topographic-isostatic reduction methods of Airy-Heiskanen (AH) and Pratt-Hаyford (PH). The results shows Rudzki gеoid performs as well as the Hеlmert and RTM geoids (in terms of standard deviation and range of minimum and maximum values) when comparing to comparison with the GPS-levelling geoid of the test area. Rudzki inversion the sole gravimetric reduction scheme which doesnt change the equipotential surface and thus doesnt need the calculation of the indirect effect.