User’s Guide to Vertical Control and Geodetic Leveling for CO-OPS Observing Systems.

Abstract

The National Ocean Service (NOS) Center for Operational Oceanographic Products and Services (CO-OPS) is responsible for the management of a national water level measurement program. The foundation of this program is the operation and maintenance of the National Water Level Observation Network (NWLON), a network of approximately 200 continuously operating data collection stations in the U.S. coastal oceans, the Great Lakes and connecting waterways, and in U.S. Trust Territories and Possessions. The data and information from this network represent one of the most unique and valuable geophysical data sets available. The network provides for the determination and maintenance of vertical reference datums used for surveying and mapping, dredging, coastal construction and restoration, water level regulation, marine boundary determinations, tide prediction, and determination of long-term water level variations (e.g. trends). The station platforms and telemetered data are used to support major U.S. Government programs such as the NWS Tsunami Warning System, the NWS storm surge monitoring programs, the U.S. Army Corps of Engineers (USACE) national dredging program, the USACE/Canadian Great Lakes regulation program, and the NOAA Climate and Global Change Program. This guide provides references to several National Geodetic Survey (NGS) documents related to the standard methodologies and tools used to derive geodetic elevations using differential and trigonometric leveling. These references do not supersede the information in this document as this document is specifically written to determine and monitor water level sensor and bench mark network elevations for the determination of tidal datums and subsequently the sea level trend.