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GLOSS (and MedGLOSS, GCOS etc.). Philip L. Woodworth Permanent Service for Mean Sea Level. GLOSS The Global Sea Level Observing System Also known as “ Global Level of the Sea Surface”. GLOSS Objectives.
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GLOSS (and MedGLOSS, GCOS etc.) Philip L. Woodworth Permanent Service for Mean Sea Level
GLOSS The Global Sea Level Observing System Also known as “Global Level of the Sea Surface”
GLOSS Objectives • Establishment of high quality global and regional sea level networks for application to climate, oceanographic and coastal sea level research • Sea level stations around the world for long term climate change and oceanographic sea level monitoring • Coordinated by the Intergovernmental Oceanographic Commission (IOC) • Major contributor to IOC’s Global Ocean Observing System (GOOS)
Some History • GLOSS was initiated in the 1980s with the aim of increasing the quantity and quality of month and annual MSL data to the Permanent Service for Mean Sea Level (PSMSL) • A network, now called the GLOSS Core Network, was defined to which all countries would contribute • These ideas formed the basis for the first GLOSS Implementation Plan
More History • By the 1990s there had been many technical developments in sea level measurement: Satellite Altimetry GPS for measuring land movements • The second GLOSS Implementation Plan was written to define: GLOSS Core Network A sub-network for Long Term Trends A sub-network for Altimeter Calibration A sub-network for Ocean Circulation
Ways of Measuring Sea Level Changes Altimeter System Bottom Pressure Gauge Tide Gauge (float)
Ways of Measuring Land Level Changes GPS Absolute Gravity
More History continued • Another important change was that tide gauge authorities were asked to provide their ‘higher frequency’ sea level data (e.g. hourly values or similar) in addition to MSL values to the PSMSL. • Two GLOSS Date Centres defined in addition to PSMSL: GLOSS Fast Centre at Hawaii (where ‘fast’ means data in a few weeks e.g. for altimeter calibration) GLOSS Delayed Mode Centre alongside PSMSL
Real Time Data in 2000’s • Most recently there has been a request for as much GLOSS data to be delivered in near real time: 1. Allows data to be provided to a new set of users e.g. tsunami people. 2. Allows faults to be identified and fixed earlier and so also better delayed-mode data eventually. • GLOSS Fast Centre at Hawaii also defined to be the GLOSS Real Time Centre
GLOSS Status GLOSS status can be measured by how well the network is providing data to data centres: • MSL data available at PSMSL • Real-time data available at Real-Time Centre • Delayed-mode data available at Delayed-Mode Centre
GLOSS Activities • Regional Developments • Regional networks of gauges with greater spatial density, to serve • the particularoceanographic interests of those regions - examples: • IOCARIBE (Caribbean), MedGLOSS (Mediterranean & Black Seas) • National Activities • Contribution to the activities ofnational agencies by improving the • standards forsea level recording around the world • Training • Annual training courses on the techniques of tide gaugeoperations, • and workshops on special interests e.g. measurements in • environmentally hostile areas
Responsibilities of GLOSS Data Providers • There are 3 responsibilities of GLOSS data providers: • Monthly and annual MSL data to PSMSL by 6 months after the data-year • Delayed-mode higher-frequency data (typically hourly values), quality controlled to one of the GLOSS centres (in practice PSMSL again or UHSLC) 4 months after recording • ‘Fast’ H-F data (not quality controlled) to GLOSS Fast Centre at UHSLC
GLOSS Data Availability • Data from GLOSS tide gauges • Permanent Service for Mean Sea Level • http://www.pol.ac.uk/psmsl/ • University of Hawaii Sea Level Center • http://www.soest.hawaii.edu/UHSLC/ • Also Regional Centres • MedGLOSS
GLOSS and GCOS The Global Climate Observing System has defined a set of approximately 180 tide gauges for long term climate (sea level) monitoring These can to a good approximation be considered the same sites as the GLOSS Core Network In a similar way as the IOTWS has major overlap with the GLOSS Network in the Indian Ocean Conclusion is that all networks have to be ‘multiple use’.
GLOSS - The Global Sea Level Observing System Further Information GLOSS Technical Secretary Permanent Service for Mean Sea LevelIntergovernmental Oceanographic Proudman Oceanographic Laboratory Commission (IOC), UNESCOemail: t.aarup@unesco.org email: psmsl@pol.ac.uk http://www.pol.ac.uk/psmsl/programmes/gloss.info.html