Wrangell Narrows Tide Stations Wrangell, Alaska

TerraSond conducted tide level observations at a minimum of three times weekly to the National Oceanic and Atmospheric Administration (NOAA)/National Ocean Service (NOS) specifications to establish tertiary tidal benchmarks. The final datum reductions, computations, and tidal benchmark elevations were published by NOAA/NOS.

Static Global Positioning System (GPS) observations were used to tie the tide stations into the existing geodetic control network along Wrangell Narrows. Four historical tide stations were recovered for this survey: Point Lockwood (9451263), Beecher Pass (9451287), Anchor Point (9451317) and Papke's Landing (9451346). At each of these four stations, two DAA Waterlog Bubbler tide gauge systems were installed to provide a stand-alone backup system, as well as to provide an independently collected and redundant tide data set for the purpose of data continuity, quality assurance, and orifice movement monitoring.

Each individual tide gauge was equipped with a completely independent power system consisting of three sealed gel-cell 12-volt batteries, charged by a 75-watt solar panel. Each gauge's data was transmitted in near real-time to the Geostationary Operational Environmental Satellite (GOES), as well as downloaded manually three times per week.

Our field crews performed the initial and final benchmark and tide observation leveling. A Team Member was used for the interim tide observations and data download.

The surveys involved the following:

• The recovery and documentation of four existing (historical) tide stations and their associated benchmarks;
• The addition of complementary benchmark monuments; third-order differential leveling through these monuments both prior to tide data collection as well as after;
• A minimum of 30 days of continuous tide level data collection on NOAA/NOS-approved tide gauges at each site; and
• Continuous monitoring of data integrity.

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