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Observing Sea LevelR KleesDepartment of Geoscience & Remote Sensing11/29/12University of TechnologyDelft     Delft     Uni...
What is sea level?•    Distance of water level from some reference point•    Absolute and relative sea level•    (Global) ...
How is sea level measured?                                          Floats + satelliteTide gauge   Satellite radar altimet...
Tide gauge measurement systemBasic principle                            Ruler edged staff                      Observing S...
Tide gauge technical realizations                        Radar gauge @ Liverpool                                          ...
25 well-selected tide gauge records     20     15     10           5ΔSL (mm)           0       -5   -10   -15             ...
Satellite radar altimetry                            Observing Sea Level   7
MSL from satellite radar altimetry        10-day coverage of Topex & Jason                                                ...
Observing changes in the volume of   ocean water …ARGO                      GRACE                             … due to cha...
Observing ocean water temperaturefloats                          ARGO                               Surface               ...
ARGO network               Observing Sea Level   11
Changes in the volume of ocean waterRA versus ARGO+GRACE                        GRACE versus RA-ARGO ARGO versus RA-GRACE ...
Some issues with sea level records• Vertical land movement                                                   GPS          ...
Some issues with sea level records• Uneven geographic distribution                 PSMSL stations                         ...
Some issues with sea level records• Uneven geographic distribution        PSMSL stations with record > 60 yrs             ...
Some issues with sea level records• Uneven geographic distributionRegional mean sea level trends(Jan 1993 – April 2012)   ...
Some issues with sea level records• Calibration of radar altimeters                                                      N...
Predicted present-day impact of GIA…… on relative sea level change      … on absolute sea level changemeasured by tide gau...
New techniques for sea level measurements                                 Spar buoy, NOAAWaverider GPS buoy, University   ...
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Observing Sea Level

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Presentation given by Roland Klees at the symposium on Sea Level Rise by TU Delft Climate Institute
http://bit.ly/Y5dPvY

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Observing Sea Level

  1. 1. Observing Sea LevelR KleesDepartment of Geoscience & Remote Sensing11/29/12University of TechnologyDelft Delft University of Technology Challenge the future
  2. 2. What is sea level?•  Distance of water level from some reference point•  Absolute and relative sea level•  (Global) Mean sea level fixed point on land relative sea level absolute sea level Observing Sea Level 2
  3. 3. How is sea level measured? Floats + satelliteTide gauge Satellite radar altimetry gravimetry Observing Sea Level 3
  4. 4. Tide gauge measurement systemBasic principle Ruler edged staff Observing Sea Level 4
  5. 5. Tide gauge technical realizations Radar gauge @ Liverpool Acoustic gaugeClassical float gauge @ Hamburg (from ~1832) Observing Sea Level 5
  6. 6. 25 well-selected tide gauge records 20 15 10 5ΔSL (mm) 0 -5 -10 -15 Rate ~ 1.8 ± 0.1 mm/yr -20 1900 1920 1940 1960 1980 2000 Nerem 2005 Year Observing Sea Level 6
  7. 7. Satellite radar altimetry Observing Sea Level 7
  8. 8. MSL from satellite radar altimetry 10-day coverage of Topex & Jason North Sea mean sea level seasonal signals removed ))) NOAA )) Change in mean sea level [mm] trend: 1.7 ± 0.4 mm/year ) ) 100 ) Laboratory for Satellite Altimetry NOAA•NESDIS•STAR 0 Jason-2 -100 Envisat Jason-1 GFO Observing Sea Level ERS-2 8 TOPEX 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
  9. 9. Observing changes in the volume of ocean water …ARGO GRACE … due to changes in…due to changes inocean water density + total ocean water mass Observing Sea Level 9
  10. 10. Observing ocean water temperaturefloats ARGO Surface Pressure Profile data Observing Sea Level 10
  11. 11. ARGO network Observing Sea Level 11
  12. 12. Changes in the volume of ocean waterRA versus ARGO+GRACE GRACE versus RA-ARGO ARGO versus RA-GRACE ARGO GRACE Leuliette & Miller 2009 Observing Sea Level 12
  13. 13. Some issues with sea level records• Vertical land movement GPS Abs grav Geology or GIA models Observing Sea Level 13 2000-2050
  14. 14. Some issues with sea level records• Uneven geographic distribution PSMSL stations Woodworth et al 2011 Observing Sea Level 14
  15. 15. Some issues with sea level records• Uneven geographic distribution PSMSL stations with record > 60 yrs Woodworth et al 2011 Observing Sea Level 15
  16. 16. Some issues with sea level records• Uneven geographic distributionRegional mean sea level trends(Jan 1993 – April 2012) Observing Sea Level 16
  17. 17. Some issues with sea level records• Calibration of radar altimeters Nerem 2005 •  ± 0.4 mm/yr tide gauge calibration error •  dominated by errors in vertical land movement from GPS data Sea Level Observing 17
  18. 18. Predicted present-day impact of GIA…… on relative sea level change … on absolute sea level changemeasured by tide gauges measured by radar altimetry … on change in water mass Observing Sea Level 18 Tamisiea 2011 measured by GRACE
  19. 19. New techniques for sea level measurements Spar buoy, NOAAWaverider GPS buoy, University GNSS altimetry 19 Observing Sea Level of Tasmania (PARIS concept)

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