GPS-controlled tide gauges in Indonesia – a German contribution to Indonesia's Tsunami Early Warning System

Abstract

Abstract. Coastal tide gauges do not only play a central role in the study of climate-related sea level changes but also in tsunami warning systems. Over the past five years, ten GPScontrolled tide gauge systems have been installed by the German Research Centre for Geosciences (GFZ) in Indonesia to assist the development of the Indonesian Tsunami Early Warning System (InaTEWS). These stations are mainly installed at the Indonesian coastline facing the Indian Ocean. The tide gauge systems deliver information about the instantaneous sea level, vertical control information through GPS, and meteorological observations. A tidal analysis at the station's computer allows the detection of rapid changes in the local sea level ("sea level events"/SLE), thus indicating, for example, the arrival time of tsunamis. The technical implementation, communication issues, the operation and the sea level event detection algorithm, and some results from recent earthquakes and tsunamis are described in this paper.

GPS water level measurements for Indonesia's Tsunami Early Warning System

“…A Butterworth low-pass filter suppresses the wind waves by removing signals with wave periods of less than two minutes. For de-tiding and estimation of the tsunami arrival time at the location of the buoy, the sea level event detection algorithm (SLE) (Schöne et al, 2011;Pérez et al, 2009) is applied. The resulting time series including the estimated onset time of a possible tsunami is transmitted via the tsunami service bus (Fleischer et al, 2010) for further use at the Tsunami Warning Center in Jakarta.…”

“…To complement the existing GPS network in Indonesia and to increase the number of possible GPS reference stations, several continuously operated high-rate GPS stations have been installed (e.g., Schöne et al, 2011) in addition to several real-time stations of the International GNSS Service (IGS) network in this area (Dow et al, 2009). …”

“…1 and 5). As a reference, the GPS-controlled tide gauge station (Schöne et al, 2011) used. For both, Telukdalam and the GPS buoy, 1 Hz data is available.…”

Postface "The GITEWS Project – results, summary and outlook"

“…The GITEWS tide gauges equipped with additional GPS sensors for position control have been installed in Indonesia and other countries around the Indian Ocean (Schöne et al, 2011a) and contribute also to the Global Sea Level Observing System (GLOSS).…”

Development of tsunami early warning systems and future challenges

“…The columns represent the different types of sensor systems, i.e. seismic (Hanka et al, 2010), buoy and ocean bottom unit (Schöne et al, 2011a), tide gauge (Schöne et al, 2011b), and cGPS (Falck et al, 2010) systems. Vertically, from the bottom to the top, the sequence of processing steps and their respective results are displayed.…”