Manual on sea level measurement and ... - unesdoc - Unesco

Sea Level Measurement and InterpretationFigure 3. Figure 3. GUI showing all stations thatwere decoded.Each time-series can be manipulated using a mouse tozoom and pick an amplitude or wave period (Figure 4).Figure 2. Transmission from the data collection platformat the field station to the warning centres.and onwards to customers such as the Pacific TsunamiWarning Center, the Japan Meteorological Agency, and toany requesting national hydrological agency (Figure 2).In the Indian Ocean, the primary satellites used fortransmission from the field stations are the JapaneseGMS for the eastern Indian Ocean and the EUMETSAToperational satellite system for the central and westernIndian Ocean. The PTWC receives its data through theUSA GOES satellite system. The satellites are part ofthe GTS. The GTS is a semi-private, reliable communicationssystemsupported by the 187-member WMO forthe transmission of environmental data, informationmessages and warnings. The GTS is the primary meansby which the PTWC receives sea level data and issuestsunami warnings.TideToolThe programme is started by typing bltwish Tide.tcl. Itdecodes the received sea level data that are found in asingle data-logging file, creates individual station filescontaining the decoded data, and starts a graphicaluser interface display that allows each station to bedisplayed as a plot (Figure 3).Figure 4. Sea level time-series plot. A mouse is usedto select the part which should be enlarged to pickthe arrival time.Tide.tcl will operate continuously once started. It willcheck every 20 s to see if any new data have arrived,and if so, it will decode and update the station timeseriesfile that is plotted. When Tide.tcl is started, itwill read data from the current day data log. Tide.tclwill keep up to 24 hours of data. As more data arrivebeyond what Tide.tcl is supposed to hold, it will discardthe older data to make room for the new. For eachstation, two gauges are decoded. The gauge code isthree letters, where prs stands for pressure sensor, bubindicates bubbler etc.For further information and questions, please contactthe IOC International Tsunami Information Centre (itic.tsunami@noaa.gov) or the Pacific Tsunami WarningCenter (stuart.weinstein@noaa.gov).78IOC <strong>Manual</strong>s and Guides No 14 vol IV