Geoscience Reference
In-Depth Information
design goal of a four-year lifetime (Figure 4.8), which would reduce the need to fund ship time
for station maintenance. The second choice implies that DART stations are maintained spar-
ingly, with only minimal attention to the integrity of the network's tsunami detection capabil-
ity, until the reliability of the DART stations is improved. In this case, it must be understood and
acknowledged
that the DART network might be fully deployed but will not be fully functional
until such time as the reliability of the DART stations gets much closer to the design goal of a
four year lifetime than the present median time-to-failure of just over one year.
A partial amelioration of the draconian choices above could come from exploring new
maintenance paradigms, such as (1) simplifying the DART mooring for ease of deployment
from small, contracted vessels that are available, for instance, from the commercial ishing leet
and the University-National Oceanographic Laboratory System (UNOLS) leet; and (2) maintain-
ing a reserve of DART buoys for immediate deployment upon the occurrence of a signiicant
gap in the network, weather permitting.
The transfer of the DART technology from research (at PMEL) to operations (at NDBC) did
not include the establishment of mechanisms for scientiic or TWC operational feedback into
the management of the program.
Conclusion:
There is insuficient station redundancy in the DART network. Since the build-
up of the DART network began in 2006, it has experienced signiicant outages that have
a potentially adverse impact on the capability of the TWCs to issue eficient warnings, use
near-real-time forecasts, and cancel the warnings when a tsunami threat is over. Worse,
multiple, neighboring DART stations have been seen to fail in the North Paciic and North
Atlantic, leaving vast stretches of tsunami-producing seismic zones un-monitored. This
situation persists for long periods of time. The committee considers it unacceptable that
even a neighboring pair of DART stations in high-priority regions is inoperative at the
same time. Although an 80 percent performance goal may be satisfactory for the entire
DART network, and for individual gauges, a much better performance is required for
neighboring pairs of DART stations, especially in high-priority regions.
Recommendation:
In order to bring NDBC into compliance with P.L. 109-424, NDBC
should engage in a vigorous effort to improve the reliability of the DART stations and
minimize the gaps caused by outages.
Conclusion:
The transfer of the DART technology from research (PMEL) to operations
(NDBC) did not include the establishment of mechanisms for scientiic or operational
feedback from PMEL or the TWCs into the management of the program. The DART
network reliability could be enhanced by improving the technological and scientiic
knowledge transfer between PMEL and NDBC and the management of the continued joint
development of next generation DART stations.
Conclusion:
Continued engineering reinements of the DART concept will allow NOAA to
establish a more sustainable capability with reduced costs of construction, deployment,
