Investigation of the Vertical Movement of the Great Lake Using Times Series of GPS Data

T. Richardson, D. A. Grejner-Brzezinska, C. Toth, G.L. Mader

Abstract:	Height Modernization Program, which has been designed and is being implemented by the National Geodetic Survey (NGS) is an ongoing operation focused on forming accurate, reliable heights using Global Navigation Satellite System (GNSS) technology in conjunction with traditional leveling, gravity, and modern remote sensing information. The traditional method for determining the elevation of vertical benchmarks is differential leveling; the disadvantages of this technique are high cost, time consumption, and nonsystematic errors (Roman & Weston, 2011). With the advance and expansion of space-based technology, GNSS surveying has been used extensively for the production and propagation of survey control. In order for GNSS-derived ellipsoidal heights to have any physical meaning in a surveying or engineering application, the ellipsoidal heights must be transformed to orthometric heights. Accurate heights are required in numerous engineering, scientific and every-day human activities, such as mapping and construction engineering, transportation applications and navigation, where the requirement for accurate heights is not limited to but is used for periodic system calibrations and quality control check; disaster preparedness and management (e.g. evacuation route surveys, flood mapping); measuring, monitoring, and modeling crustal motion, subsidence, glacial isotactic adjustment (GIA) and seasonal changes. In order to assure high accuracy and maintainability of the height system, any change in the location of the benchmarks must be continuously monitored, and any necessary changes recorded. To this end this study analyzes using GNSS (limited to GPS only data in this study) the vertical movement of the Great Lakes. The Great Lakes are a vast hydraulic system with water levels and flows influenced by engineered channels and control structures. The existing problem for The Great Lakes and St. Lawrence River region are the postglacial rebound or glacial isostatic adjustment effect, fluctuations on a short-term, seasonal, and long-term basis (Zilkoski, 1991). The absolute rate of change at a given location must be considered along with the relative rate of change across the region. The study involves reprocessing and re-adjustment of the International Great Lakes Datum of 1985 (IGLD 85) Height Modernization projects (1997, 2005, and 2010), using OPUS-PROJECT (REFERENCE!!!) in a consistent reference frame (IGS08 or ITRF08) at the epoch of each survey. This allowed for the observation of any changes over time, without including either changes in reference frame or processing software/algorithms. This activity assured a modern, up-to-date evaluation of real movement in the Great Lakes region. Additionally a times series analysis using the longest available spans of continuous references station throughout the Great Lakes region. This allowed for the observation of any long term trends and seasonal variations. Further this study would look at the comparison of the GPS derived vertical velocities and that derived from GIA model. Overall this paper would establish how vertical movement can be accounted for when deriving centimeter level height derived from GPS.
Published in:	Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014) September 8 - 12, 2014 Tampa Convention Center Tampa, Florida
Pages:	635 - 644
Cite this article:	Richardson, T., Grejner-Brzezinska, D. A., Toth, C., Mader, G.L., "Investigation of the Vertical Movement of the Great Lake Using Times Series of GPS Data," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 635-644.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In