Sea-Level Monitoring Stations

The ability to warn a vulnerable population of the approach of a tsunami depends on a variety of measurements, initially seismic network data, but also on a network of gauges that measure the sea level along the coasts. Real-time data transmission without any significant time delays is essential because of the high speed at which a tsunami wave propagates and the time needed to implement decision-making and mitigation procedures before a warning is issued. Tide gauges are generally located at the land-sea interface, usually in locations somewhat protected from the heavy seas that are occasionally created by storm systems. Tide gauges that initially detect tsunami waves provide little advance warning at the actual location of the gauge, but can provide an indication for other communities that a tsunami does exist, its speed, and its approximate strength.

US IOTWS Contribution

Under the US IOTWS Program, the National Oceanic and Atmospheric Administration (NOAA) upgraded six sea-level stations, one each in Sibolga, Prigi, and Cilacap, Indonesia; Hanimaadhoo and Gan, Maldives; and Colombo, Sri Lanka. Scientists can now collect data and disseminate it more quickly for analyses in case of a tsunami. The stations themselves are now stronger and able to better withstand damage from storms and floods. In addition, all six stations have been integrated into the Global Sea Level Observing System (GLOSS), an international monitoring network that is coordinated by the World Meteorological Organization (WMO) and the Intergovernmental Oceanographic Commission. The GLOSS network provides essential real-time data that can be accessed by warning centers. By enabling the stations to deliver data in real-time, warning centers are notified almost immediately when an event occurs or if there is a problem with the gauge. In addition, the data become available for many other applications within operational oceanography, such as flood warning or for using sea-level data in ocean circulation models. 

Next Steps

NOAA and the University of Hawaii’s Sea Level Center (UHSLC) will continue working together with national agencies to maintain the sea-level monitoring stations and communication systems. Training and capacity building will also be conducted.

For Further Information

Mike Johnson, NOAA Office of Climate Operations (mike.johnson@noaa.gov)

Mark Merrifield, University of Hawaii Sea Level Center (markm@soest.hawaii.edu)

http://uhslc.soest.hawaii.edu/

http://www.gloss-sealevel.org/