Geoscience Reference
In-Depth Information
probability of a reliable data stream in near-real time. In addition to having access to raw
water level data via satellite transmission, CO-OPS collaborated with the TWCs to develop a
webpage (http://co-ops.nos.noaa.gov/1mindata.shtml) to disseminate 1-minute water level
data. This webpage allows users to view both 6- and 1-minute data numerically or graphically
for all tsunami-capable tide stations in increments of up to 4 days (Figure 4.2 is one example).
Like the near-real-time data, all water level data displayed through the CO-OPS tsunami
webpage are raw and unveriied at this time. However, veriied 6-minute sea level data are
available through another website (http://tidesandcurrents.noaa.gov/station_retrieve.
shtml?type=Historic+Tide+Data), usually within 2 months of collection, which enables the user
to easily evaluate the quality of the 1-minute data, although well after the occurrence of the
tsunami. The 15-second data, potentially more useful for model validation, are not telemetered
on a regular basis, but are available to the TWCs via remote phone dial-in.
The NOAA/NOS has developed and rigorously follows a set of standards for the estab-
lishment, operation, and maintenance of its critical NWLON coastal sea level stations. As well,
NOAA describes in its Tsunami Warning Center Reference Guide (U.S. Indian Ocean Tsunami
Warning System Program, 2007) the performance and maintenance standards it recommends
for sea level stations that are intended to aid tsunami detection, forecasting, and warning
activities. Unfortunately, the high-quality NOS NWLON stations make up only a small portion
of all the sea level observation stations needed for tsunami detection (Figure 4.4). Whether sea
level gauges operated and maintained by other U.S. agencies satisfy, or can be upgraded to, the
standards of the NWLON stations, or whether these other U.S. stations should be operated and
maintained under the NWLON program, are questions that remain unanswered. In addition, the
committee is not aware of any process by which the non-NOS sea level stations (U.S. or inter-
national) are evaluated or certiied relative to these standards. How much of a risk occurs as a
result of the TWC's reliance on un-certiied sea level gauges is not known.
The University of Hawaii Sea Level Center (UHSLC) Stations
The UHSLC (http://ilikai.soest.hawaii.edu/) maintains and/or operates a worldwide array
of sea level observing stations, some of which are employed in the tsunami detection and
warning process (for the Paciic Ocean, see Figure 4.4). The UHSLC is a research facility of the
University of Hawaii/NOAA Joint Institute for Marine and Atmospheric Research (JIMAR) within
the School of Ocean and Earth Science and Technology (SOEST ). The mission of the UHSLC is
to collect, process, distribute, and analyze in-situ sea level gauge data from around the world
in support of climate research. Primary funding for the UHSLC comes from NOAA's Ofice of
Global Programs (OGP). In recent years, the UHSLC, recognizing the potential importance of its
stations to tsunami hazard mitigation, has upgraded many of its stations to short period sam-
pling and reporting (http://ilikai.soest.hawaii.edu/RSL1/index.html).
Because of the UHSLC's climate research mission, which includes ascertaining the small
(typically, 1-3 mm) annual sea level rise associated with global warming, the UHSLC strives for
high operational standards and data quality. It is not known whether the UHSLC's operational
standards meet or exceed the NOS NWLON maintenance standards.
