Status and needs of Sea level Observing Systems

Status and needs of Sea level Observing Systems in East and South East Asia GCOS Regional Meeting for East and South East Asia, Singapore , 16 -18 September 2002 John Church, CSIRO Australia john. church@csiro. au Philip Woodworth, POL (GLOSS Chairman) plw@pol. ac. uk Thorkild Aarup, GLOSS Technical Secretary IOC t. aarup@unesco. org C. K. Shum, Ohio State Univ. (GLOSS Asia-Pacific Regional Contact) ckshum@osu. edu Contents of Presentation: 1. Rationale - Why monitor sea level changes and how? 2. The GLOSS programme 3. Status of sea level data availability from the Region 4. Recommendations http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

Why Measure Sea Level Changes? • Coastal management requires understanding of past and future changes in sea level and related ocean conditions • Practical applications – e. g. to predict flood risks, coastal Different etc. navigation. Time-Scales • Rapid changes due to tsunamis • Daily changes due to tides and surges • Seasonal changes • Interannual changes e. g. due to ENSO • Long term changes due to climate change Causes of Sea Level Change • Local processes in river/coastal regimes • Ocean circulation changes Maldives Int. Airport • Regional and global climate changes • Geological processes

Sea level has risen by about 120 m since the last glacial maximum http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

Over several hundred years there has been an increase in the rate of sea-level rise. http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

Changes in Sea Level during the 20 th century • Most records show evidence for rising sea levels during the past century • IPCC concluded that there has been a global rise of approximately 10 -20 cm during the past 100 years http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

Some E and SE Asia Long Records Example records from India, Malaysia, Singapore, Thailand, Vietnam, Hong Kong, South Korea, Russia, Japan and Philippines. http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

Sea level rise during the 20 th century has had regional impacts. Marsh Destruction at Blackwater, Maryland, Due to Sea Level Rise Leatherman, 2001

“sea level is projected to rise by 0. 09 to 0. 88 m between 1990 and 2100” about 2 to 4 times the rate for the past 100 years For the IS 92 a greenhouse gas scenario Thermal expansion 0. 11 to 0. 43 m Glaciers and ice caps 0. 01 to 0. 23 m Greenland -0. 02 to 0. 09 m Antarctica -0. 17 to 0. 02 m

Return period of surge heights at Immingham (UK) A reduction in the return period of extreme events.

Longer Term Projections • Continued glacier melting • East Antarctic Ice Sheet • West Antarctic Ice Sheet opinion not favouring catastrophic collapse • Continued thermal expansion for centuries • Greenland melting greater than +3 C then continued melting +5 C - 3 m over 1000 years

Projected Coastal Megacities: 2010 By 2100, the number of people who will have to respond to coastal flooding will be tens of millions/year; Most vulnerable regions are South and South-East Asia; Africa; Carribean; Indian Ocean Islands; Pacific Ocean Islands. Tianjin Dhaka Seoul Osaka Istanbul Tokyo New York Shanghai Los Angeles Manila Bangkok Lagos Bombay Lima Karachi Buenos Aires Rio de Janeiro Madras Jakarta Calcutta

Measuring Sea Level Changes Altimeter System Tide Gauge (float) Bottom Pressure Gauge http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

Tide Gauges are still essential in the “Age of Altimetry” • Principle of continuity, relative low cost of gauges • Long records for trend/acceleration studies (e. g. for input to IPCC) secular • Higher frequency sampling important • High latitude regions of ice coverage • Altimeter calibrations (‘absolute’ and ‘relative’) Acoustic Gauge in Australia • Coastal applications (GOOS Coastal Module) http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html • Vertical land motion (using GPS)

GLOSS - The Global Sea Level Observing System • For many years agencies have sent data to the PSMSL. GLOSS aims to ensure the provision of high quality sea-level data for regional and global applications. • Establishment of high quality regional and global sea level networks for application to climate, oceanographic and coastal sea-level issues • Coordinated by the Intergovernmental Oceanographic Commission (IOC) for the JCOMM of WMO/IOC • Major contributor to IOC’s Global Ocean Observing System (GOOS) http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

The GLOSS Programme • GLOSS Core Network (GCN) • Regional Densifications of the GCN • Long Term Trends (LLT) • Altimeter calibration (GLOSS-ALT set) • Ocean Circulation (GLOSS-OC set) GLOSS Core Network (GCN) with approx. 280 stations http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

An effective regional and global system requires: delayed mode original data (e. g. hourly values) be sent to one of the GLOSS International Archiving Centres (Most countries are now doing this but it remains a problem for a few (e. g. national security, or cost recovery)). IAC’s are PSMSL, Univ. Hawaii and National Tidal Facility Australia. fast sea level data to be sent from GLOSS Core Network sites to the GLOSS Fast Centre (University of Hawaii Sea Level Center) within one week.

GCN Status E. and S. E. Asia GCN Status Category: Measured by PSMSL data receipts • up-to-date • a bit slow • historical data only • no data http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html

Status of data submission (see http: //www. pol. ac. uk/psmsl/reports. national+regional/) India – no hourly data, national security issues Bangladesh – major investments needed in difficult estuary environment Myanmar – first contact for many years made in 2002 Thailand – MSL delivered promptly, but gauges need upgrading Malaysia – excellent tide gauge and GPS networks Singapore – excellent tide gauge and GPS networks

Vietnam – new recent gauges for flood warning. PR China – MSL delivered regularly if a bit behind. More gauges are known to exist than provide data to international data banks. Hong Kong China – long standing data provision. Japan – excellent networks of several agencies. S. Korea – good gauges. MSL data behind. N. Korea – contacts lapsed. Russia – good formal contacts. Several gauges destroyed by tsunami. Need for modernisation. Philippines – long standing contacts lapsed. Indonesia – large gauge networks, none of which now work due to funding problems.

Major Issues for the Region Comparatively few tide gauges in the region are equipped with GPS for monitoring vertical land movements (major exception of Japan), see http: //www. soest. hawaii. edu/cgps_tg Need for major investment in upgrade of tide gauges (e. g. for fast data provision as well as delayed-mode) and for GPS alongside the gauges. (No plans as yet for bids, e. g. to World Bank, for resources for the region, as for Africa. )

Historical data GLOSS/IODE Data Archaeology Project Agencies which have historical sea level data in non-computer form (e. g. on paper charts, or paper tape) are asked to inform IOC or PSMSL which may be able to arrange for computerisation of the information.

Ongoing Regional Activities • Regional networks of gauges with greater spatial density, to serve the particular oceanographic interests of those regions - example: Asia-Pacific Space Geodynamics (APSG) activities • Research in the measurement and characterization of Asia. Pacific regional and global sea-level rise • Data center to be established, potentially at NTF, or other sites providing data products including sea-level measurements, wave heights, wind speed, and integrated water vapor from multiple satellites • GLOSS contributes to the activities of national agencies by improving the standards for sea level recording around the world • Annual training courses on the techniques of tide gauge operations, and workshops on special interests e. g. measurements in environmentally hostile areas. Next course http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html Malaysia April 2003.

Recommendations Establish a Regional Project, under the auspices of GLOSS, to further develop a networks of modern tide gauges and geodetic instrumentation to serve regional requirements. Specific Recommendations Employ a Regional Coordinator to pursue the Regional Project. That historical data (hourly, delayed mode and fast data) be submitted to the GLOSS data archives (including if necessary, conversion to computer compatible form) That tide gauge instrumentation at GLOSS sites be upgraded to allow efficient quality control and submission of delayed mode and fast data. That a subset of gauge sites be equipped with Continuous GPS (CGPS) receivers and/or other geodetic devices, in order to monitor vertical land movement. That tide gauges suitable for ongoing calibration of satellite altimeter missions (e. g. deep ocean islands) be included in international programs (GLOSS-ALT). That the project also contribute to observations quantifying the causes of sea level change. That programs be established to study the social, economic and environmental consequences of sea level change; including the impact and frequency of

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/ • National Tidal Facility (Australia) Southern Ocean Centre http: //www. ntf. flinders. edu. au GLOSS sea level data and information on each gauge in the GLOSS Core Network are also available from PSMSL on CDROM. Further Information GLOSS Technical Secretary Intergovernmental Oceanographic Commission (IOC), UNESCO email: t. aarup@unesco. org Permanent Service for Mean Sea L Proudman Oceanographic Laboratory email: psmsl@pol. ac. uk http: //www. pol. ac. uk/psmsl/programmes/gloss. info. html