ESRL Global Systems Division

FSL Supports the NOAA/NOS Great Lakes Partnership Program

Water level fluctuations in the Great Lakes have a direct impact on shoreline change, wetland habitats, coastal development, commercial shipping, and recreation. NOAA's Great Lakes Environmental Research laboratory (GLERL) reports that since 1998, the levels of Lakes Michigan and Huron have dropped at the fastest rate ever recorded. Regardless of the causes, there are concerns about the impact of changing water levels in the region. Water and coastal managers, as well as the public, depend on current and accurate information about the lake levels to support short and long-range decisions.

A network of water level monitoring sites in the U.S. and Canada monitor the levels of the Great Lakes. The gauges at these sites are currently tied to an obsolete geodetic reference system that renders the measurements qualitatively useful but quantitatively imprecise. In addition, water levels based on the old system are inconsistent with modern digital charts and navigation systems such as GPS. A new project sponsored by the NOAA National Ocean Service (NOS) Partnership Program is aimed at improving the accuracy of the International Great Lakes Datum (IGLD), an elevation reference system used to define water levels within the Great Lakes-St. Lawrence River system. This will be accomplished by installing approximately 22 continuously operating GPS reference stations (CORS) at selected water level sites along the Great Lakes in the U.S. and Canada. GPS and surface meteorological data acquired at these sites will be used to convert relative water level changes measured via the water level gauges into absolute changes. The goal is to better monitor, and then forecast, the impacts of water level changes on shorelines, wetland habitats, and coastal development. The project directly supports activities such as mapping, charting, and international water resources management in the Great Lakes region. Also, GPS measurements made at these sites will enable scientists and engineers to track land movements associated with post-glacial rebound and land subsidence.

The network is a collaborative effort between FSL and the NOAA National Geodetic Survey (NGS), NOAA Center for Operational Oceanographic Products and Services (CO-OPS), the Ohio State University (OSU), Canadian Hydrographic Service, National Resources Canada, NOAA Research's Great Lakes Environmental Research Laboratory (GLERL), the NWS Central and Eastern Regions, the U.S. Coast Guard, and the Michigan Department of Transportation. For its part, FSL has installed surface meteorological sensors at 10 U.S. Coast Guard Maritime Differential GPS sites in the Great Lakes Region. Due to a fortuitous synergy between the requirements for high accuracy positioning and meteorological remote sensing, these GPS sites can also be used to monitor the total quantity of precipitable water vapor in the atmosphere with high accuracy under all weather conditions. The GPS and surface meteorological observations will be collected by FSL, processed, and made available to NWS forecasters, modelers, and researchers in near real-time.

Contact information
Name: Seth Gutman
Tel: 303-497-7031