West Coast/Alaska Tsunami Warning Center

Operations Manual

NOAA/NWS/WCATWC

910 South Felton Street

Palmer, Alaska 99645

Section 2.4: Sea Level Network Description

Last Updated: 5/2007

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Several types of sea level data are recorded at the WCATWC, including tradtional tide gage data, deep ocean pressure sensor data, and data from radar gages and pressure sensors at sites operated by the tsunami warning centers. In total, signal from over 300 different gages are recorded. Overall sea level data flow is depicted in Section 3.3.

The majority of sea level data recorded at the WCATWC are transmitted in near real-time via the GOES or GMS satellites, through NESDIS/NWS telecommunications gateway, and back to WCATWC via the NWS Alaska Region Line 223 and the Palmer/Anchorage link. These sea level gages are operated by many organizations; such as National Ocean Service (NOS), the Pacific Tsunami Warning Center (PTWC), National Data Buoy Center, Japanese Meteorological Agency, University of Hawaii Sea Level Center, Chile, Canadian Hydrographic Service, and the National Tidal Facility in Australia. Data transmission rates vary from 1-minute sample data transmitted every 6 minutes to 6-minute sample data transmitted hourly.

A network of 27 deep-ocean tsunami recorders, or DART buoys, also transmit data via the Iridium satellite phone system to the warning centers. Plans are in place to upgrade this network to 39 sites (32 in the Pacific and 7 in the Atlantic) by 2008.

WCATWC operates radar tide gages at Shemya, Akutan, Old Harbor, and Craig, Alaska to supplement the NOS network. A fifth site is maintained in collaboration with the Alaska Volcano Observatory at Amchitka, Alaska. The WCATWC network data is recorded in real-time through the VSAT seismic network data communications system and provided to the PTWC. This data can be viewd at wcatwc.arh.noaa.gov/WCATWCtide.php. Sea level data are also received directly from the PTWC in real-time. Pprocessing software is discussed in Section 4.2.