Assessment of Various Ocean Tide Models on GNSS Data over Nigerian Continuously Operating Reference Stations

Abstract

Nigeria has a long coast line with some of its GNSS Continuously Operating Reference Stations (CORS), otherwise known as NIGNET located in this coastal environment. It is therefore essential to identify an appropriate model that could perform optimally over Nigeria. Hence, this paper examines the effects of various ocean loading models on the accuracy of data processing over the NIGNET CORS. The study was conducted using selected five Ocean Tide Models (OTMs) which include FES2004, FES2012, FES2014b, GOT00.2 and HAMTIDEOTMs. The five ocean loading models were downloaded from Onsala Space Observatory and separately utilised for GNSS data processing, one month (October, 2011) of the NIGNET data was used. The result was subjected to statistical analysis using their corresponding RMSE to recommend the most appropriate model for processing CORS data over Nigeria. HAMTIDE OTM performed best with a RMSE range of 0.6mm to 1.43mm followed closely by GOT00.2 OTM with RMSE range of 0.6mm to 1.46mm. FES2014b had a RMSE range of 0.74 mm to 1.52 mm. FES2004 had a RMSE range of 0.76 mm to 1.69 mm. FES2012 OTM showed the least performance with a RMSE range of 3.96mm to 7.09mm. It was concluded that HAMTIDE OTM and GOT00.2 OTM are the most preferable for GNSS data processing over Nigeria.