Tsunami Forecasting Observational Network
Eddie Bernard , NOAA/Pacific Marine Environmental Laboratory, Lead Author
Co-Authors:
Christian Meinig & Vasily Titov, NOAA/Pacific Marine Environmental Laboratory
Kathleen O’Neil, NOAA/ National Data Buoy Center
Robert Lawson, SAIC
Kenneth Jarrott, Australian Bureau of Meteorology, JCOMM
Rick Bailey, Australian Bureau of Meteorology, IGC-IOTWS
Filomena Nelson, Samoa Disaster Management Office, IGC- PTWS
Stefano Tinti, University of Bologna, IGC- NEAMTWS
Lorna Inniss, Barbados CZM Unit, IGC- Caribe EWS
Peter Koltermann, IOC/Tsunami Unit
To forecast tsunamis requires real-time deep-ocean tsunami observations and, in some
cases, coastal observations reported in time to generate and disseminate warning
information before the tsunami strikes coastlines. Existing operational technology to
meet this rigid requirement includes accurate pressure measurements (<1cm) from
seafloor sensors relayed within 2 minutes to warning centers for real-time data
assimilation into forecast models to disseminate forecast products to threatened
coastlines. An internationally supported network of these instruments, named
tsunameters, was created following the devastating 2004 Indian Ocean tsunami. An ad
hoc group of Nations and suppliers, named the International Tsunameter Partnership
(ITP), was formed to set guidelines for the manufacture* and operations** of these new
instruments. The reference document for these summaries is attached as Tsunameter
Equipment Standards….doc. The ITP has recently merged with the Joint WMO-IOC
Technical Commission for Oceanography and Marine Meteorology (JCOMM).
Operational coastal observations are also required where tsunameters are not available or
to validate forecasts where tsunameters are available. This white paper will only address
the tsunami requirements as GLOSS will cover the sustainability of coastal sea level
observations in a separate white paper.
This white paper will focus on how the tsunameter network and coastal gauges will
evolve and be sustained over the next decade. It will also outline a process for indentify
emerging technologies that may offer alternative ways of obtaining measurements at the
same observational quality. Another contribution will be the process for integrating
pressure measurements with other ocean observations for the benefit of the global ocean
observation system. Finally, how the observations serve the needs of and provide benefit
to the user community, whether scientific, intermediate and/or end users will be
presented.
* INTERNATIONAL TSUNAMETER MEASUREMENT STANDARDS
Summary
Mandatory Characteristic
Measurement sensitivity
Sampling interval, internal record
Sampling interval, event reports
Sampling interval, tidal reports
Two-way end-to-end communications
Tsunami data report trigger
Data flow, BPR to TWC
Specification
Less than 1 millimeter in 6000 meters; 2 * 10-7
15 seconds
15 and 60 seconds
15 minutes
On demand, tsunami warning center (TWC)
trigger
Automatically by tsunami detection algorithm
Less than 3 minutes after triggered event
Desired Characteristic
Reliability and data return ratio
Maximum deployment depth
Minimum deployment duration
Operating Conditions
Theoretical Battery Life, buoy
Theoretical Battery Life, tsunameter
Maximum status report interval
Specification
Greater than 80%
6000 meters
1 year
Beaufort 9
Greater than 2 years
Greater than 4 years
Less than 6 hours
** Tsunameter Performance Procedures
Summary
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Measurement: Sea-level amplitude at a continuous sample rate of 15 seconds over
time.
Measurement accuracy: Agreement within 1.0 cm in the observed tides deployed
in similar depths off Hawaii within 100 nm of operational DART station using a
standard tide model for tidal adjustments between stations.
Measurement Resolution: 0.25mm at depths 1000-6000 meters.
Performance measure: Comparison of Standard Mode data with harmonic tidal
analysis shows agreement within 5 cm (average) over a 14 day period during the
120 day evaluation period.
Reliability- 80% or better data return rate over 120 consecutive days.
False triggers, not related to natural events: None during 120 day evaluation
period.
Data delivery; Request Mode*:
– Gage Trip: Elapsed time from request for data to receipt of data at the
tsunami warning center's server less than 10 minutes.
– Gage 15sec data (1 hour duration): Elapsed time from request for data to
receipt of data at the tsunami warning center less than 15 minutes.
Data delivery; Event Mode*:
– Gage Trip: Elapsed time from trip to receipt of data at tsunami warning
center's server: less than 3 minutes; and display on the NDBC web site:
less than 5 minutes (pre-selected times via software setup)
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Data acquisition tests*: At least one successful test acquiring one hour of 15
second data during 120 day evaluation period.
Performance measure: Comparison of 15 sec data with DART station data with
harmonic tidal analysis shows agreement within 5 cm (average) over a 1 hour
period during the 120 day evaluation period.
Other Bottom Pressure Recorder (BPR) commands tests**: At least one
successful test for each of the following during 120 day evaluation period.
– Turn on "deployment mode" for 30 minutes.
– Retrieve engineering data from gage.
– Reboot BPR gage electronics.
– Reboot buoy electronics.
– Change tsunami detection threshold.
Tsunami Test Mode: In the event of a detectable tsunami the test buoy tsunami
data will be compared with operational DART station data. Amplitude and phase
comparison should show 90% or better agreement after properly taking into
account the differences in tsunami amplitude differences and arrival times
between the two stations.
Performance results are provided to and documented in accordance with standards
of the NOAA Tsunami Program.