Evaluation of global geopotential models: a case study for India

Abstract

This paper aims to identify most suitable global geopotential model (GGM) for India, by comparing 15 GGMs developed through 1996 to 2017. The GGM derived geoid undulation values are compared with the geometrical undulation values obtained from GNSS/levelling data on Indian vertical datum. A correction term is added to the computed GGM derived geoid undulation value after fitting three-, four-, five- and seven-parameter models to account for bias and tilt between local geometric Indian vertical datum and global gravimetric vertical datum. The results indicate that EGM2008 model is the best GGM available for India with root-mean-square error (RMSE) of 0.28 m, without model fitting. However, after considering the systematic errors in the two datums with seven-parameter model, GECO GGM has shown significantly better results with RMSE of 0.19 m for India.

Keywords:

• GGM
• Geoid undulation
• Accuracy
• Bias and tilt
• Parameter models
• India

Acknowledgement

The authors would like to thank Dr Christopher Jekeli and Dr Siamak Moazezi for providing conceptual help in developing the MATLAB based software for the computation of geoid undulation.

ORCID

Ropesh Goyal http://orcid.org/0000-0002-2178-3265