Effects of Tropospheric Refraction on Precise Point Positioning in Brazil: EFEITOS DA REFRAÇÃO TROPOSFÉRICA NO POSICIONAMENTO POR PONTO PRECISO NO BRASIL

Autor: Braga, Franciele Lúcia Silva, Dal Poz, William Rodrigo
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Pesquisas em Geociências; v. 49 n. 2 (2022): Pesquisas em Geociências; e118014
ISSN: 1518-2398
1807-9806
Popis: Troposphere is one of the most limiting sources of error in the accuracy of 15 Precise Point Positioning method. This work aims to analyze the effects of tropospheric 16 delay on this positioning technique by applying the Bernese scientific program to GNSS 17 data belonging to the Brazilian Network for Continuous Monitoring of GNSS Systems. 18 GNSS data are related to several climatic zones, including Amazon region, referring to four 19 seasons. The data were processed considering six strategies, each one using different 20 troposphere models and mapping functions for analysis. Results were evaluated according 21 to the Root Mean Square, estimated for 15 processing days for each season, involving 89 22 GNSS stations. Results show that the greatest effects of the tropospheric delay occurred in 23 the equatorial region, related to the altimetric component, in all seasons of the year. This 24 climatic zone is under a strong influence of the Amazon region, which presents high annual 25 humidity values. In addition, it can occur a great humidity variation in this region, which 26 can compromise the process of estimating wet component of tropospheric delay. Finally, 27 results showed that the best processing strategy was the use of the Vienna mapping function 28 in conjunction with corrections based on the Numerical Weather Forecast model.
Troposphere is one of the most limiting sources of error in the accuracy of Precise Point Positioning method. This work aims to analyze the effects of tropospheric delay on this positioning belonging to the Brazilian Network for Continuous Monitoring of Global Navigation Satellite Systems (GNSS). The tropospheric delay is generated by the influence of the hydrostatic and dry atmosphere. Corresponds to about 2.3 m at zenith for hydrostatic component, 1 to 35 cm at zenith for wet component. Although the wet component is generally smaller, its temporal and spatial variation is much greater, which makes its modeling difficult. GNSS data are related to several climatic zones, including Amazon region, referring to four seasons. The data were processed considering six strategies, each one using different troposphere models and mapping functions for analysis. Results were evaluated according to the Root Mean Square, estimated for 15 processing days for each season, involving 89 GNSS stations. For the planimetric result, the best result was obtained in the frequency histogram in which the Hopfield model was used for the hydrostatic component and the Hopfield mapping function for the estimated wet component (5% of the sample with an accuracy greater than 3 cm). The best processing method in relation to the altimetric component was obtained using the Vienna mapping function - VMF1, together with the Zenith Tropospheric Delay (ZTD) corrections based on the Numerical Weather Forecast/European Center for Medium-Range Weather Forecast (NWF /ECMWF) model (94.2% of the sample accuracy less than 3 cm). Results show that the greatest effects of the tropospheric delay occurred in the equatorial region, related to the altimetric component, in all seasons of the year. This climatic zone is under a strong influence of the Amazon region, which presents high annual humidity values. In addition, it can occur a great humidity variation in this region, which can compromise the process of estimating wet component of tropospheric delay. Finally, results showed that the best processing strategy was the use of the Vienna mapping function in conjunction with corrections based on the Numerical Weather Forecast model.
Databáze: OpenAIRE
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