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: 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.