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Regional Models

Turkey (TG-20)


  Authors: H. Yıldız, et al.     Created: 2020    Resp: Y.A. Akdoğan  
      Status: PUBLIC    
Description:
Turkish Geoid Model-2020 (TG-20) is currently the official geoid model for Turkey computed by the General Directorate of Mapping, the national mapping agency. It is a hybrid model extending from 35°N to 43°N and from 25°E to 45°E. It was determined using more than 265,000 point gravity data, as well as the GOCO06S global geopotential model and a digital elevation model of 7.2 arc-second resolution based on SRTM V4.1. Free-air gravity anomalies over marine areas and neighboring countries at 1’×1’ resolution were computed using the XGM2019e model up to degree and order 5399. The computation was based on the Least-Squares Modification of Stokes’ Formula with Additive Corrections (LSMSA) method using the LSMS-GEOLAB scientific software. The transformation of the gravimetric model was carried out via 4-parameter fit to 182 historical and homogenously distributed GPS/levelling data. Absolute validation of the resulting hybrid model with 278 recent GPS/levelling data yielded standard deviations ranging from 1.2 cm to 6.3 cm (below 2 cm at almost every test profile) which brought about considerable improvement over the previous official geoid models. TG-20 with 5 arc-min spatial resolution is freely available to the public.

Reference:
H. Yıldız, M. Simav, E. Sezen, İ. Akpınar, Y.A. Akdoğan, A. Cingöz, O.A. Akabalı (2021). Determination and validation of the Turkish Geoid Model-2020 (TG-20). Bollettino di Geofisica Teorica ed Applicata, 62(3), pp. 495-512. DOI: 10.4430/bgta0345


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