The difference between height anomaly and geoid height in Vietnam according to the global gravity field model SGG-UGM-2

Abstract

The purpose of this study is to determine the difference between height anomaly and geoid height
in Vietnam. The formulas for calculating height anomalies, geoid heights and the differences between them
have been studied. The experiment was performed in the Vietnam area with latitude limit: 8ºN - 24ºN;
longitude: 102ºE - 114ºE with data from the global Earth Gravity Model SGG-UGM-2 and the Terrain
Model ETOPO1. The experimental results show that: In the study area, the geoid height increases
gradually in the Northwest - Southeast direction, has a negative value in the Northwest, has a positive value
in the Southeast, and has a value smaller than the height anomaly. The difference between the height
anomaly and the geoid height varies from 0 to 0.445 m, with decimeter-scale values in mountainous areas,
centimeter-scale values and smaller in plain areas, and zero over the East Sea. This study provides an
understanding of the differences between geoid and quasigeoid in the territory and territorial waters of
Vietnam.