Estimation of the Geopotential Value W₀ for the Local Vertical Datum of Argentina Using EGM2008 and GPS/Levelling Data W ₀ ^LVD

The main purpose of this paper is to estimate the zero-height geopotential value for the Argentinean Local Vertical Datum (LVD). The methodology is based on the computation of the mean geopotential offset between the value W ₀ = 62,636,856.0 m² s⁻², selected as reference in this study, and the unknown geopotential value of the LVD (W ₀ ^LVD ). This estimation is based on the combination of ellipsoidal heights, levelled heights (referring to the LVD), and some physical parameters derived from the EGM2008 model (namely, geopotential values, gravity values, and geoid undulations). This combination is performed following two approaches: The first one compares levelled heights and geopotential values derived from the EGM2008 model using the Least Squares method to increase the robustness of the adjustment, while the second one analyses the differences between GPS/Levelling and EGM2008 geoid undulations. Both approaches are evaluated at more than 540 benchmarks (BMs) belonging to the vertical network of Argentina. The numerical computations include in addition the assessment of possible correlations of the estimated zero-height geopotential value with the height of the included BMs. The results show that the best possible estimation at present is 62,636,853.9 m² s⁻²; however, it is necessary to improve these computations by including proper physical heights (instead of the levelled ones) and global gravity models containing GOCE data.