Abstract
We have established a stable regional geodetic reference frame using long-history (13.5 years on average) observations from 55 continuously operated Global Navigation Satellite System (GNSS) stations adjacent to the Gulf of Mexico (GOM). The regional reference frame, designated as GOM20, is aligned in origin and scale with the International GNSS Reference Frame 2014 (IGS14). The primary product from this study is the seven-parameters for transforming the Earth-Centered-Earth-Fixed (ECEF) Cartesian coordinates from IGS14 to GOM20. The frame stability of GOM20 is approximately 0.3 mm/year in the horizontal directions and 0.5 mm/year in the vertical direction. The regional reference frame can be confidently used for the time window from the 1990s to 2030 without causing positional errors larger than the accuracy of 24-h static GNSS measurements. Applications of GOM20 in delineating rapid urban subsidence, coastal subsidence and faulting, and sea-level rise are demonstrated in this article. According to this study, subsidence faster than 2 cm/year is ongoing in several major cities in central Mexico, with the most rapid subsidence reaching to 27 cm/year in Mexico City; a large portion of the Texas and Louisiana coasts are subsiding at 3 to 6.5 mm/year; the average sea-level-rise rate (with respect to GOM20) along the Gulf coast is 2.6 mm/year with a 95% confidence interval of ±1 mm/year during the past five decades. GOM20 provides a consistent platform to integrate ground deformational observations from different remote sensing techniques (e.g., GPS, InSAR, LiDAR, UAV-Photogrammetry) and ground surveys (e.g., tide gauge, leveling surveying) into a unified geodetic reference frame and enables multidisciplinary and cross-disciplinary research.
Highlights
The Gulf of Mexico (GOM) is located at the south end of the North American tectonic plate and north of the Caribbean plate
According to our previous investigations [31,32], within the southern portion of the North American plate, a Global Navigation Satellite System (GNSS) site that is not affected by localized subsidence retains a vertical site velocity well below 3 mm/year with respect to International GNSS Service (IGS) global reference frames (e.g., IGS08, International GNSS Reference Frame 2014 (IGS14))
GOM20 could result in accumulated positional-errors of 4.5 mm in the horizontal directions and 7.5 mm in the vertical direction across a 15-year window, which are still comparable with the RMS-accuracy of the daily GNSS measurements (PPP solutions)
Summary
The Gulf of Mexico (GOM) is located at the south end of the North American tectonic plate and north of the Caribbean plate. Despite the overall tectonic stability of the GOM region, localized ground deformation associated with fault creeping and land subsidence has caused frequent damages to residential and commercial structures as well as the public infrastructure. The research community has difficulties in establishing a unified and consistent datum (reference frame) across the entire GOM region to evaluate long-term land deformation and sea-level changes. The regional reference frame was realized using seven-year-long continuous observations from 13 GNSS stations adjacent to GOM. During the past two decades, Interferometric Synthetic Aperture Radar (InSAR), light detection and range (LiDAR), and Unmanned Aerial Vehicle (UAV) photogrammetry techniques have been frequently employed for mapping land subsidence, faulting, and coastal erosion within the GOM region [8,26,27,28,29,30]. Applications of remote sensing techniques further prompted the need for a unified reference frame to align measurements from different remote sensing systems
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