Spatial variation of precipitable water vapor derived from GNSS CORS in Thailand

This research aims to study a distance variation of Precipitable Water Vapor (PWV) between Continuously Operating Reference Stations (CORS) in Thailand using a Precise Point Positioning (PPP) technique. Nowadays, Global Navigation Satellite System (GNSS) CORS is not only used to obtain precise positioning applications but also plays an important role in meteorological applications. With a recent establishment of GNSS CORS around Thai region, the PWV can be accurately derived from these GNSS CORS data using the scientific Position and Navigation Data Analyst (PANDA) GNSS processing software. One-year period of GNSS CORS data collected between January 1 and December 31, 2016 are used in this study. The GNSS CORS data used in this study are gathered from various agencies, i.e. Chulalongkorn University, Department of Lands and Department of Public Works and Town & Country Planning. However, a coverage distance from each GNSS CORS for PWV estimations is not precisely determined for Thai region. This information can help reduce expenses in an installation and maintenance of meteorology sensors at each GNSS CORS. Therefore, this paper focuses on determining the distance variation of PWV between GNSS CORS and the coverage distance from each CORS for PWV estimations. The result shows that the coverage distance from each CORS at 74 km or less can provide accurate PWV in Thai region. Keywords: Continuously operating reference stations (CORS), Precipitate water vapor (PWV), Global navigation satellite system (GNSS), Precise point positioning (PPP