Albania (ALBGG2024/ALBHG2024)
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Authors: D.A. Natsiopoulos, et al.
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Created: 2024
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Resp: O. Balliu
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Description:
A preliminary geoid model for Albania was computed in the framework of the modernization of the Albanian geodetic reference system, promoted by the State
Authority for Geospatial Information (ASIG). The model covers the area between 38.5°N and 43.5°N latitude and 18.0°E and 22.0°E longitude, with a spatial
resolution of 1′ × 1′. The gravity database consists of 53,151 free-air gravity anomalies derived from terrestrial and marine sources. The terrestrial
dataset includes 634 newly observed gravity points and 521 historical measurements in Albania, together with 2,246 gravity observations from Greece.
Marine gravity data were derived from the DTU2021 and SIO29.1 models, while EGM2008 was used to provide additional gravity information in neighboring
regions and reduce boundary effects. The geoid computation was performed according to the remove-compute-restore (RCR) procedure. The long- and medium-wavelength
components of the gravity field were represented using the EIGEN6C4 global geopotential model up to degree and order 2190. The effects of topography were
evaluated using spectral residual terrain modelling (RTM) based on a combination of national and global digital terrain models. A gravimetric geoid, called ALBGG2024, was
computed using the two-dimensional Fast Fourier Transform (FFT) technique with a modified Stokes kernel. This model was validated using 225 GNSS/levelling benchmarks distributed
over Albania and additional observations along newly established precise levelling lines. The comparisons with GNSS/levelling data showed a standard deviation of 12.7 cm. A hybrid
geoid, called ALBHG2024, was subsequently obtained by fitting a third-order polynomial surface to the GNSS/levelling residuals. This approach reduced the standard deviation of the
differences to 11.5 cm. This solution enables the direct transformation of ellipsoidal heights in the terrestrial reference system ETRS89/ETRF2000 (also known as KRGJSH in Albania)
and orthometric heights in the Albanian vertical reference system (ALB86).
References:
D.A. Natsiopoulos, G.S. Vergos, K. Qirko, O. Balliu, E. Qershija, L. Kasnec, P. Ndoj (2026). A new gravimetric and hybrid geoid model in Albania.
International Association of Geodesy Symposia, pp. 1–13. DOI: 10.1007/1345_2026_337
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