The California Spatial Reference System

Gregory A. Helmer

Abstract:	California presents a unique challenge to the successful implementation and maintenance of a high-precision geodetic reference network. Crustal motion in the form of tectonics, local and regional seismic activity, volcanic expansion, and land subsidence makes any geodetic control campaign temporal at best. Difficult terrain in the form of vast deserts, remote mountains and offshore areas introduce questions as to the reliability of the geoid model, and compound the difficulty of water vapor modeling in the troposphere. These unique challenges are issues within the most populous state in the nation -- a region that on its own is the seventh largest economy in the world. Decreasing federal programs frustrate the problem and place increasing responsibility for solutions at the local level. The California Spatial Reference Center (the Center) has been formed as a partnership with federal, state and local agencies, business and educational institutions, to provide for a state-of-the-art spatial reference framework for the state of California. The Center is based at the University of California San Diego Scripps Institution of Oceanography. At the heart of the mission for the Center is establishing a state-of-the-art geodetic reference system to support modern spatial referencing needs in a dynamic environment. Building upon the infrastructure of Continuous Operating Reference Stations (CORS), data processing and data management at the Scripps Institute for Geophysics and Planetary Physics, the Center is dedicated to providing the necessary geodetic services to ensure accurate and consistent spatial referencing of information throughout California. The California Spatial Reference System (CSRS) provides one accurate, consistent spatial reference network that will fulfill the many diverse spatial referencing needs of California's users. This paper discusses the different components of the CSRS including current coordinates and elevations, data processing and distribution infrastructure, geodetic and geophysical models, and professional education programs directed at successful implementation of the system. Modern technology has made it feasible to distribute via the Internet near-real-time coordinates. While this type of data is invaluable to geophysical science, it presents a dilemma for surveying and mapping. Crustal motion models, such as the Horizontal Time-Dependent Positioning Model (HTDP) from NGS, and the Southern California Velocity Field Model from the Southern California Earthquake Center, provide the ability to integrate published positions and GPS observations, from various epoch dates, to a common epoch. Proper application of these modeling methods is a new subject for most GPS survey professionals. Advancing education in this area is a high priority for the California Spatial Reference Center. Up to date information on activities at the Center, and an interface to the geodetic data and management structure can be found at the organizations web site at http://csrc.ucds.edu.
Published in:	Proceedings of the IAIN World Congress and the 56th Annual Meeting of The Institute of Navigation (2000) June 26 - 28, 2000 The Catamaran Resort Hotel San Diego, CA
Pages:	644 - 649
Cite this article:	Helmer, Gregory A., "The California Spatial Reference System," Proceedings of the IAIN World Congress and the 56th Annual Meeting of The Institute of Navigation (2000), San Diego, CA, June 2000, pp. 644-649.
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