Dr. Robert Suya

Dr. Robert Suya

Author

Land Surveying & Physical Planning

33 publications

Suya earns a PhD in Navigation and Satellite Positioning from the University of Nottingham. He also has an MSc in Geodesy and Engineering Surveying from the same university. Suya is a Global Navigation Satellite Systems (GNSS) enthusiast and a renowned geodesist who specialises in utilising satellit...

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Applying Malawi Continuously Operating Reference Stations (CORS) in GNSS Meteorology

Journal Article
Published 2 years ago, 623 views
Author
Dr. Robert Suya
Co-authors
Mr. Charles Kapachika, John Bosco Ogwang, Harvey Chilembwe, Francis Gitau, Dr. Robert Suya
Abstract
Global Navigation Satellite System (GNSS) signals in the L-band are affected by the non-dispersive neutral atmosphere. Regardless of their center frequency, the L-band code and phase observations are affected by the same measure of delay. GNSS receivers play a significant role in quantifying the zenith tropospheric delay (ZTD) from satellite signals. Malawi has a Continuously Operating Reference Stations (CORS) network which was established to support research in geophysical geodesy and geodynamics. However, the quality of the observations tracked by the CORS has never been tested in terms of its meteorological application. In this paper, the ZTD estimation approach and the evaluation of results from the Global Positioning System (GPS) measurements are presented. The optimal approach of precise point positioning (PPP) was used to estimate ZTD from one-week datasets which were collected from six CORS monuments distributed in the northern and southern regions of Malawi. In addition, the zenith wet delay (ZWD) and zenith hydrostatic delay (ZHD) were also estimated to determine their respective contributions to the total delay in all the stations. Alongside the meteorological parameters, the positioning repeatabilities were also established for all stations. Results indicate that the averaged ZTD, ZWD and ZHD can reach as high as 247mm, 47 mm, and 199 mm, respectively. The minimum ZTD, ZWD, and ZHD for the stations can drop to as low as 220 mm, 24 mm, and 181 mm, respectively. This indicates that the ZHD contributes to more than 90% of the total delay at the stations. For the positioning performance, there was no obvious disparity in the latitude (less than 0.5 cm), longitude (less than 1 cm), and ellipsoidal height repeatabilities (less than 1.5 cm). Thus, the results clearly demonstrate that the Malawi CORS network may be used for GNSS-based meteorological applications using the available geodetic receivers. However, for high-precision meteorological applications, Malawi may consider densifying the available network with geodetic grade receivers.
Year of Publication
2022
Journal Name
South African Journal of Geomatics
Volume
11
Issue
2
Page Numbers
218-233
Supporting Files
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