GLOSS (and MedGLOSS, GCOS etc.)

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GLOSS (and MedGLOSS, GCOS etc.)

• Philip L. Woodworth
• Permanent Service for Mean Sea Level

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GLOSS The Global Sea Level Observing System Also
known as Global Level of the Sea Surface
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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 IOCs Global Ocean
  Observing System (GOOS)

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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

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The GLOSS Core Network
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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

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Ways of Measuring Sea Level Changes
Altimeter System
Bottom Pressure Gauge
Tide Gauge (float)
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Ways of Measuring Land Level Changes
GPS
Absolute Gravity

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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

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Real Time Data in 2000s

• 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

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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

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GLOSS Real-time coverage 22 September 2006
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GLOSS Activities

• Regional Developments
• Regional networks of gauges with greater spatial
  density, to serve
• the particular oceanographic interests of
  those regions - examples
• IOCARIBE (Caribbean), MedGLOSS (Mediterranean
  Black Seas)
• National Activities
• Contribution to the activities of national
  agencies by improving the
• standards for sea level recording around the
  world
• Training
• Annual training courses on the techniques of
  tide gauge operations,
• and workshops on special interests e.g.
  measurements in
• environmentally hostile areas

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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

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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

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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.
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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_at_unesco.org email
psmsl_at_pol.ac.uk
http//www.pol.ac.uk/psmsl/programmes/gloss.info.h
tml