DRUKGEOID2022 is the official geoid model of Bhutan, covering the area from 88.5°E to 92.5°E in longitude and from 26.5°N to 28.5°N in latitude with a grid resolution of 0.02°. It is an update of the previous DRUKGEOID2015 model, that was changed by a bias of 0.8761 m. This update was due to the change of the reference benchmark from the TH01 station at NLC headquarters to the more reliable THIZ station belonging to the national zero-order GNSS/levelling network. In this way, the resulting geoid can be used for the conversion from ellipsoidal heights in the DRUKREF03 system (ITRF2000 at epoch 2003.87) to orthometric heights in the national vertical datum, which is in turns connected to the Indian mean sea level through the neighboring benchmarks in the Indian states of West Bengal and Assam. Comparison of 27 GNSS/levelling benchmarks with DRUKGEOID2022 showed a standard deviation of 0.55 m.
The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.
The International Service for the Geoid (ISG) was founded in 1992 (as International Geoid Service - IGeS) and it is now an official service of the International Association of Geodesy (IAG), under the umbrella of the International Gravity Field Service (IGFS). The main activities of ISG consist in collecting, analysing and redistributing local and regional geoid models, as well as organizing international schools on the geoid determination (Reguzzoni et al., 2021).
