| Abstrakt: |
The ability to precisely and accurately model and predict tropospheric delay is essential for precise global navigation satellite system (GNSS) and meteorological applications. The International GNSS Service (IGS) provides highly accurate and highly reliable daily time series zenith tropospheric delay (ZTD) products for all its member sites using data from each IGS site. Nevertheless, if for reasons such as poor internet connectivity, equipment failure, and power outages the IGS station is inaccessible, gaps are created in the data archive, resulting in degrading the quality of the ZTD estimation, as well as inhibits the quality of precipitable water vapour (PWV) estimation, needed for precise positioning applications, meteorological studies, and weather forecasting. To address this challenge, five regression models are proposed in this study to model and predict daily ZTDs using daily datasets from four IGS stations in West Africa over a period of 5 years (2015–2019). The site‐specific Vienna Mapping Functions 3 (VMF3) products (ZTD, pressure, temperature, water vapour partial pressure) and stations' coordinates (latitudes and longitudes) are used as the predictors, while the IGS final ZTD product as the response variable in fitting the models. Several performance measures are calculated to compare the predictive performance of the models. The results show that the five regression models performed outstandingly and agree very well with the IGS‐ZTD data, and hence provide a useful alternative for ZTD predictions and also in the event the West African IGS stations' ZTD data are unavailable. Nonetheless, the support vector regression model outperformed the remaining four models.The extended functionality of GNSS into varied applications such as GNSS meteorology, remote sensing, and so forth has necessitated the establishment of a vast and ever‐growing network of International GNSS Service (IGS) ground‐tracking stations worldwide. Large data gaps resulting from inadequate and inconsistency of continuous data streaming from the West African IGS stations obstruct daily continuous ZTD estimates and consequently inhibit the quality and continuous retrieval of precipitable water vapour (PWV) needed for meteorological studies and weather forecasting. Addressing this challenge using regression models is essential. [ABSTRACT FROM AUTHOR] |
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