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| Titel |
The GNSS data processing component within the Indonesian tsunami early warning centre provided by GITEWS |
| VerfasserIn |
M. Bartsch, A. Merx, C. Falck, M. Ramatschi |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250033813
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| Zusammenfassung |
| Introduction
Within the GITEWS (German Indonesian Tsunami Early Warning System)
project a near real-time GNSS processing system has been developed, which analizes
on- and offshore measured GNSS data. It is the first system of its kind that was
integrated into an operational tsunami early warning system. (Indonesian Tsunami Early
Warning Centre INATEWS, inaugurated at BMKG Jakarta on November, 11th
2008)
Brief system description
The GNSS data to be processed are received from sensors (GNSS antenna and receiver)
installed on buoys, at tide gauges and as real-time reference stations (RTR stations), either
stand-alone or co-located with seismic sensors. The GNSS data are transmitted to the warning
centre in real-time as a stream (RTR stations) or file-based and are processed in a near
real-time data processing chain.
The fully automatized system uses the BERNESE GPS software as processing core.
Kinematic coordinate timeseries with a resolution of 1 Hz (landbased stations) and 1/3 Hz
(buoys) are estimated every five minutes. In case of a recently occured earthquake the
processing interval decreases from five to two minutes. All stations are processed with the
relative technique (baseline-technique) using GITEWS-stations and stations available via IGS
as reference. The most suitable reference stations are choosen by querying a database where
continiously monitored quality data of GNSS observations are stored. In case of an
earthquake at least one reference station should be located on a different tectonic plate to
ensure that relative movements can be detected. The primary source for satellite orbit
information is the IGS IGU product. If this source is not available for any reason, the system
switches automatically to other orbit sources like CODE products or broadcast ephemeris
data.
For sensors on land the kinematic coordinates are used to detect deviations from their
normal, mean coordinates. The deviations or so called displacements are indicators for land
mass movements which can occur, e.g., due to strong earthquakes. The ground
motion information is a valuable source for a fast understanding of an earthquake’s
mechanism and consequences with possible relevance for a potentially following
tsunami.
Regarding kinematic coordinates of a buoy only the vertical component is of interest as it
corresponds to the instant sea level. The kinematic coordinates are delivered to an
oceanographic post-processing unit which applies dipping-, tilting- and tidal-corrections to
the data. Deviations to the mean sea level are an indicator for a possibly passing tsunami
wave. By this means the GNSS system supports the decision finding process whether a
tsunami has been released or not.
A graphical user interface (GUI) was developed which monitors the whole processing
chain from data transmission and GNSS data processing to the displaying of the kinematic
coordinate time series. It supports both, a quick view for all staff members at the warning
centre (24h/7d shifts) and deeper analysis by GNSS experts. The GNSS GUI system is
web-based and allows all views to be displayed on different screens at the same time,
even at remote locations. This is part of the concept, as it can support the dialogue
between warning centre staff on duty or on standby and sensor station maintenance
staff.
Acknowledgements
The GITEWS project (German Indonesian Tsunami Early Warning System) is carried out
by a large group of scientists and engineers from (GFZ) German Research Centre for
Geosciences and its partners from the German Aerospace Centre (DLR), the Alfred Wegener
Institute for Polar and Marine Research (AWI), the GKSS Research Centre, the
Konsortium Deutsche Meeresforschung (KDM), the Leibniz Institute for Marine
Sciences (IFM-GEOMAR), the United Nations University (UNU), the Federal
Institute for Geosciences and Natural Resources (BGR), the German Agency for
Technical Cooperation (GTZ) and other international partners. Most relevant partners
in Indonesia with respect to the GNSS component of GITEWS are the National
Coordinating Agency for Surveys and Mapping (BAKOSURTANAL), the National
Metereology and Geophysics Agency (BMG) and the National Agency for the
Assessment and Application of Technology (BPPT). Funding is provided by the
German Federal Ministry for Education and Research (BMBF), Grant 03TSU01. |
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