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Operations Manual

NOAA/NWS/WCATWC

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Palmer, Alaska 99645

 

 

Section 2.4: Sea Level Network Description

 

Last Updated: 7/2008

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Several types of sea level data are recorded at the WCATWC, including traditional tide gage data, deep ocean pressure sensor data, and data from radar gages and pressure sensors.  In total, signal from over 400 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 NWS Telecommunications Lines 276 (the WC/ATWC ARH link and dedicated comms from ARH to NWSTG) and 277 (public internet from Palmer to NWSTG).  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 15 second sample data transmitted in real time to 15-minute sample data transmitted every six hours. 

 

A network of 39 deep-ocean tsunami recorders operated by the National Data Buoy Center (32 in the Pacific and 7 in the Atlantic), or DART buoys, also transmit data via the Iridium satellite phone system to the warning centers.  In addition to these, Chile operates 1 DART off its shore, Australia operates two east of Australia, and two are located west of Indonesia and Thailand in the Indian Ocean (operated by those two countries).

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.  Processing software is discussed in Section 4.2.