1. GLOSS Global Sea Level Observing System Bernie Kilonsky University of Hawaii (GLOSS Group of Experts) Thorkild Aarup Intergovernmental Oceanographic Commission (GLOSS Technical Secretary, t.aarup@unesco.org) Mark Merrifield University of Hawaii (Chair GLOSS Group of Experts)

2. How Are GLOSS Tide Gauges Used? Acoustic Gauge in Australia Altimeters need to be calibrated using gauges Continuity and low cost. The altimeter record may have gaps in future and we need the GLOSS network for global variability information Long mean sea level (MSL) records needed for climate change studies (e.g. for IPCC) Long records of higher frequency climate change (e.g. changes in storm surge statistics) Many coastal applications. People live at the coast and not in the deep ocean. Higher frequency sampling important for storm and tsunami monitoring and warning.

3. Many GLOSS sites report real-time high frequency sea level information on an hourly transmission cycle to the Pacific Tsunami Warning Center.

5. INDIAN OCEAN TIDE GAUGES FOR TSUNAMI WARNING STATUS, JANUARY 2005 12 GLOSS UHSLC Stations - operating, 2-4 minute sample period, 1 hour transmission 4 GLOSS UHSLC Stations - operating, 4-6 minute sample period, no satellite transmission 1 GLOSS Australian Station - operating, 6 minute sample period, satellite transmission 3 GLOSS Australian Stations - 1 hour sample period, 1 week - 1 month delivery 4 GLOSS Stations - operating, 1 hour sample period, 1 week - 1 month delivery Ko Lak, Ko Taphao Noi, Richard's Bay, Tanjong Pagar GLOSS Stations - Proposed installations, 1 minute sample, 15 minute transmission Minicoy, Madras, Vishakhapatnam (SOI-UHSLC), Padang, Cilacap (Bakosurtanal-UHSLC)

9. What does GLOSS offer? Global data archiving facility with QC of data Training courses on analysis & uses of sea level obs. Technical expert visits Technical manuals and training material Special workshops on technical issues (i.e. How to operate a gauge in harsh ocean environments; New technical developments in sea and land level observations) Provision of gauges Assistance with development of proposals for upgrade tide gauge hardware

10. Given Many GLOSS sites are already using geostationary satellites and the WMO’s GTS to provide data for tsunami monitoring and warning to PTWC. The added sustainability and importance of an ocean observing system tailored to meet the needs of all (i.e., multiple use stations). The existing infrastructure and expertise in the collection of in situ sea level information available through GLOSS in terms of field operations, training programs, and data centers. The value of GLOSS tide gauges as demonstrated during the Indian Ocean and other tsunamis, It is highly recommended that Full advantage is taken of the GLOSS program when developing a global tsunami warning system. In particular, the expansion and upgrade for tsunami warning of the GLOSS Core Network of tide gauges should be a high priority for the international community.