The Global Sea Level Observing System (GLOSS) Andrew Willmott

Transcription

1 The Global Sea Level Observing System (GLOSS) Andrew Willmott

2 A Big Scientific Issue Sea Level Rise The rate of global mean sea level rise increased between the 19 th and 20 th century MSL rose by 1-2 mm/year during the 20th century and 3 mm/year during the 1990s that was a high decadal rate although not unprecedented Why has sea level been rising and how much might it rise in the future? (several 10s cm suggested in the IPCC TAR) Extreme sea levels are also known to be increasing, in most places roughly in line with change in MSL How might extremes change in future and how will they impact coastal environment and infrastructure?

3 Sea level change contains an acceleration of sea level rise from the 19 th to the 20 th centuries probably due to climate change

4 (Holgate and Woodworth, GRL 2004)

5 Sea Level Rise Understanding and predicting sea level change is the responsibility of international study groups e.g. WCRP Workshop UNESCO, Paris, June 2006 findings to be published in book form in 2007 IPCC 4AR - to be published February 2007 However, it is clear that understanding cannot come without information based on a copious and high quality global sea level data set based on tide gauge, altimeter, archaeological and geological information.

6 Many Other Scientific and Practical Issues Measurements of sea level gradients by means of altimetry and tide gauges is the most straightforward way of measuring ocean currents Tide gauges are needed for monitoring storm surges and tsunamis and for application to a wide range of Operational Oceanography Sea level data are needed for many practical applications e.g. port operations, coastal engineering, tide tables etc. The world needs the best possible global, regional and national sea level monitoring networks

7 GLOSS The Global Sea Level Observing System Also known as Global Level of the Sea Surface

8 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) for JCOMM Major contributor to IOC s Global Ocean Observing System (GOOS)

9 Some History GLOSS was initiated in the 1980s with the aim of increasing the quantity and quality of monthly 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

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11 Longer PSMSL records from China Most show evidence for rising levels (and are not studied in detail in the international literature?)

12 The GLOSS Core Network

13 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 Regional networks

14 New Technology for sea level in the 1990s Satellite Altimetry Absolute Gravity GPS

15 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 Data Streams 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

16 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

17 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

18 (latest data 2002, 1992, older, no data at all)

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20 GLOSS Examples of Upgrades in Progress Indian Ocean major GLOSS investment following the 2004 tsunami Africa major investment from ODINAFRICA (Flanders and IOC)

21 Recent and Upcoming Installations and Upgrades in the Indian Ocean

22 Recent and Upcoming Installations and Upgrades in Africa Ceuta Funchal Las Palmas Tan Tan Suez Palmeira Nouakchott Dakar Aberdeen Point IOC Odin Africa POL/UK NOAA BCLME France Spain Portugal Nigeria Uncommitted Conakry Abidjan Ascension Takoradi Sao Tome St. Helena Tristan da Cunha Lagos Port Sonara Walvis Bay Simonstown Pointe Noire Lobito Inhambane Djibouti Lamu Mombasa Pointe La Rue Zanzibar Mtwara Dzaoudzi Pemba Nosy Be Durban Port Elizabeth Mogadishu Tamatave Hafun Port Louis Reunion Is. Fort Dauphin

23 Many Present-day Elements of GLOSS Coordination mechanism re. global sea level obs. (GLOSS Group of Experts) Global data standards & archiving facilities with QC of data Technical manuals and training material Technical advice and special workshops on technical issues Training courses on analysis & uses of sea level observations Technical assistance with hardware upgrades (some provision of gauges, gps, transmitters..; proposal advice)

24 Responsibilities of GLOSS Data Providers 1. Monthly and annual MSL data to PSMSL by 6 months after the data-year 2. 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 3. Fast H-F data (not quality controlled) to GLOSS Fast Centre at UHSLC

25 EXAMPLES OF WHAT POL (with BODC) DOES FOR GLOSS GLOSS was a POL and UH initiative the first operational component of GOOS Chairman Data centres (PSMSL, Delayed Mode Centre) and associated functions (web pages etc.) UK and S Atlantic gauges for the GLOSS Core Network Organisation of GLOSS training courses Organisation of GLOSS meetings and technical workshops Writing of technical manuals Technical advice and development e.g. recently, ODINAFRICA tide gauge provision, BGAN telemetry development

26 POL Sea Level Stations in the South Atlantic and Antarctic 7 Sea Level Stations Real time telemetry: Ascension Island Saint Helena Port Stanley Delayed data retrieval: Signy Island Vernadsky (Faraday) Rothera Tristan to be re-built after storm damage

27 POL and IOC are installing 14 gauges in Africa. 12 (red) with ODINAFRICA funds. 2 (blue) in Mozambique were the first ones - installed with GLOSS funds.

28 Liverpool BGAN Tide Gauge developed with Africa and Tsunami System in mind Contains radar gauge, pressure gauge and BGAN terminal

29 GCOS The Global Climate Observing System (GCOS) 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 gauges have to be multiple use including local use.

30 Some Conclusions It is obvious that the scientific and coastal communities need GLOSS Progress developing GLOSS has been slow in developing countries partly because of low level of local expertise and interest Can POGO help to develop local scientific and technical expertise? The 2004 tsunami and Flanders interest in Africa have been major reasons for increased recent funding They, and worldwide general interest in climate change, have provided a Window of Opportunity to close many of the gaps in GLOSS has been an excellent year for GLOSS However, many other gaps remain due to national limitations in contributing to international objectives (due to bureaucracy, national security, data commercialisation )

31 Some Conclusions GLOSS is concerned with one relatively easyto-measure parameter (sea level) GLOSS was a founder component of GOOS and success with GLOSS will point to how well GOOS itself will develop In turn GLOSS and a GOOS will be major components of a GEO

32 GLOSS - The Global Sea Level Observing System Further Information GLOSS Technical Secretary Intergovernmental Oceanographic Commission (IOC), UNESCO t.aarup@unesco.org Permanent Service for Mean Sea Level Proudman Oceanographic Laboratory psmsl@pol.ac.uk