CoAuthors

International GNSS Service (IGS) TIGA Working Group (, )

Sea level change is of great concern to society. For decades to centuries the sea level has been traditionally measured using shore tide gauges. However, gauges only constitute a local datum, affected not only by climate but also by local land changes. Space geodetic techniques are the only viable tool to establish the necessary global reference frame for constraining sea level records to a common global datum. Providing this frame facilitates the distinction between the relative and absolute sea level changes by accounting for the vertical uplift of the station, and is, therefore, an important contribution to climate changes studies. It also allows using tide gauge derived sea level time series as long-term stable ground truth for radar altimetry calibration.
The IGS Tide Gauge Benchmark Monitoring - Working Group (TIGA-WG) is providing the service to analyze GNSS data from stations directly at or near tide gauges (TG) on a preferably continuous basis. TIGA is recognized by the Global Sea Level Observing System (GLOSS) to provide position and vertical rates for GLOSS tide gauges and is an important contribution of the IGS to the goals of the Global Geodetic Observing System (GGOS), the Global Climate Observing System (GCOS) and the World Climate Re-search Programme (WCRP).
The primary TIGA product is weekly sets of coordinates, velocities, and accuracy esti-mates for monitoring vertical motions of Tide Gauge Benchmarks (TGBM). The product is made public to support and encourage other applications, e.g. sea level studies. The service may further contribute to the calibration of satellite altimeters, other oceanographic applications or the establishment of a World Height System.
The Working Group is utilizing the existing infrastructure of the IGS as much as possible without disrupting standard activities. A number of TIGA Analysis Centers (TAC) pro-vides weekly solutions using the IGS reprocessing standards. The TIGA network will additionally include non-IGS stations (TIGA Observing Stations, TOS) meeting the IGS network requirements and are collocated with the tide gauges. The TIGA Product will be generated by TIGA Combination Centers (TCC). The network maintenance and interaction with TOS operators is supported by the TIGA Network Coordinator (TNC), closely related to the support of the TIGA Data Centers (TDC).
Recently, the TIGA-WG started a reprocessing effort for a large number of GNSS stations near or at tide gauges. The five groups will provide individual and combined solutions spanning 1995 to 2013. First results will be shown demonstrating significant improvements compared to previous efforts.

Links
http://adsc.gfz-potsdam.de/tiga
http://www.sonel.org
http://www.igs.org