RAMIN KIAMEHR - department of geodesy and geomatics, zanjan University, Iran

According to C.F. Gauss. The geoid is the mathematical figure of the Earth, and in fact, of the gravity field. The geoid surface is more irregular than the ellipsoid of revolution often used to approximate the shape of the physical Earth, But considerably smoother than the Earths physical surface. While the latter has excursions of the over of 8 km (Mount Everest) and -11 km (Mariana Trench), The geoid varies only about ±100m about the reference ellipsoid of revolution. The main objective of the least-squares modification of the stokes formula is to minimize effects of the errors in the estimation of the geoid. The modification mathods proposed by Sjoberg allow for minimization of the truncation errors, The influence of erroneous gravity data. geopotential coefficients and combination of different data sources in the least-squares sense and at the same time in a optimum way. A new geoid model for Iran colputed based on this method.

geodesy, geoid Iran, Stokes formula, least-squares modification