[G02-P] Poster

[G02-P-03] Regional geoid computation by Least Squares Modified Hotine's formula with Additive Corrections

Silja Mardla¹, Artu Ellmann¹, ^○Jonas Agren², Lars E. Sjoberg³ (1.Tallinn University of Technology, Tallinn, Estonia, 2.Lantmateriet, The Swedish Mapping, Cadastral and Land Registration Authority, Gavle, Sweden, 3.KTH, Royal Institute of Technology, Stockholm, Sweden)

Geoid and quasigeoid modelling from gravity anomalies by the method of Least Squares Modification of Stokes' formula with Additive Corrections (LSMSA) is adapted for the usage with gravity disturbances and Hotine's formula. The biased, unbiased and optimum versions of least squares modification are considered. Equations are presented for the four additive corrections that account for the combined (direct plus indirect) effect of downward continuation (DWC), topographic, atmospheric or ellipsoidal corrections in geoid or quasigeoid modelling. The geoid or quasigeoid modelling scheme by the least squares modified Hotine formula is numerically verified, analysed and compared to the Stokes counterpart in a heterogeneous study area.

Both, the approximate geoid models (before the combined corrections) and the additive corrections computed for use with Stokes' or Hotine's formula differ most in areas of high elevation. Over the study area with elevations up to 2 km, the approximate geoid models differ by 7 mm on average with a 3 mm standard deviation (STD) and a maximum of 1.3 cm. The additive corrections, out of which only the DWC correction differs significantly, improve the agreement between respective geoid or quasigeoid models to an average difference of 5 mm with a 1 mm STD and a maximum of 8 mm.