Abstract
This research aims to study a distance variation of Precipitable Water Vapor (PWV) between CORS stations in Thailand using a Precise Point Positioning (PPP) technique. Nowadays, GNSS Continuously Operating Reference Stations (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 1 January and 31 December 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 station 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 stations and the coverage distance from each CORS for PWV estimations. The result shows that the coverage distance from each CORS station at 74 km or less can provide accurate PWV in Thai region.
Highlights
Electromagnetic waves are transmitted from satellites when the waves travel through the atmosphere reflection and refraction make waves travel faster or slower
Zenith Total Delay (ZTD) is tropospheric delay in zenith direction. εp and ε∅ are the multipath error and observation noise of ionosphere free combination observation. ( Min Li, 2014) This paper focuses on ZTD value which is obtained from Global Navigation Satellite System (GNSS) data using Precise Point Positioning (PPP) technique
Observation data preparations, GNSS observation are obtained from 10 GNSS reference stations known as GNSS data; defined as Chulalongkorn University (CUUT), Ayutthaya (AYYA), Nakhon Nayok (OKRK), Nakornpatom (BLAN), Nonthaburi (PKKT) Samut Sakhon (KTBN), Saraburi (KKOI), Samut Prakan (BPLE), Bangkok ( DTP9) and Nakhon Sawan ( NKSW)
Summary
Electromagnetic waves are transmitted from satellites when the waves travel through the atmosphere reflection and refraction make waves travel faster or slower. ( Bernhard Hofmann-Wellenhof, 2007) It consists of two components; namely, about 10% of dry part and 90% of wet part of the refraction in the atmosphere. Both components result in the arrivals of the receiver slower than the actual travelling time because the measured distance is longer than it should be. The application of the Global Navigation Satellite System (GNSS) in meteorology is another option that can be used.
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