HR: 11:05h
AN: OS21D-04    [PDF]
TI: New Approach to Sea Level Monitoring Tested at Shemya, Alaska
AU: * Urban, G W
EM: guy.urban@noaa.gov
AF: West Coast/Alaska Tsunami Warning Center, 910 South Felton Street, Palmer, AK 99645 United States
AU: Medbery, A H
EM: alec.medbery@noaa.gov
AF: West Coast/Alaska Tsunami Warning Center, 910 South Felton Street, Palmer, AK 99645 United States
AU: Burgy, M C
EM: michael.burgy@noaa.gov
AF: West Coast/Alaska Tsunami Warning Center, 910 South Felton Street, Palmer, AK 99645 United States
AB: Due to the prohibitive installation cost to replace a storm damaged stilling well type tide gauge at Earickson Air Force Station on Shemya Island, Alaska, an alternative sea-level gauge was sought by the West Coast and Alaska Tsunami Warning Center (WCATWC). An Omart-Vega radar system was chosen as the alternative, since it had low power needs, did not require a stilling well and its design included observation of rough surface liquids. The Omart-Vega radar system works by emitting a 5 gHz radar wave which reflects off the water surface and then back to the unit at a specified rate. This information is then telemetered directly to a computer which records the sample. Although the cost of the Vega system (3500USD) was similar to that of the stilling well unit (2500USD), the comparison of the installation costs of the two different units was an issue. To install the stilling well system, two certified under-water welding divers were required at a cost of 40K-USD or more. In comparison, the installation of the Vega system simply required an arm constructed so as to hang and support the Vega unit off the pier at Shemya. This arm assembly would also house the unit to protect it from surf and weather. The arm was designed in-house and built by a local metal contractor for less than 500USD. This portable unit was sent to Shemya via C-130 aircraft. The arm assembly and housed radar tide gauge was installed by one person. The circuitry to run the Vega was developed and tested at the WCATWC. Software was designed and tested there as well, although the software was written by Omart at no cost to the Warning Center. The circuitry allows for direct remote reconfiguration from Palmer to the radar system. The Vega is accessed by software directly from the WCATWC computer to sample the water level at numerous settable sample rates, which include one second, five second, fifteen second, and thirty second. After nearly one year of operation at Earickson, which included many major storms, the radar unit is proving to be a reliable substitute for the previous stilling well type gauge.
DE: 4564 Tsunamis and storm surges
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting