Introduction to the special issue on Gravity and geoid in the Asia Pacific

This special issue (SI) includes papers related to some recent efforts on geoid modeling in the Asia-Pacific region. In total, twelve papers were submitted to this SI, covering geoid models in Australia, mainland China, India, Indonesia, South Korea, Malaysia, Nepal, the Philippines, Taiwan and Thailand. The methods for geoid modeling are rather diversified, with different considerations in gravity data processing and terrain effects. It is suggested that a mechanism for gravity data sharing should be developed and software packages can be freely distributed to geoid modelers. Observed GNSS/leveling along a route over varying terrains across Taiwan are released for testing geoid modeling methods and for accuracy assessments.