Monitoring the Global Sea Level Rise Budget with Jason, Argo and GRACE Observations Eric Leuliette and Laury Miller NOAA/Laboratory for Satellite Altimetry Ocean Climate Observation 7th Annual System Review Silver Spring, Maryland 27–29 October 2010

Click to edit Master text styles Second level Third level Fourth level Fifth level NOAA Jason Program

NOAA CDR Program (NCDC) NASA Measures Program ESA Climate Change Initiative SCOPE-CM (Operational meteorological agencies: EUMETSAT, NOAA, JMA, CMA) Multiple agency efforts underway: For practical purposes, the Ocean Surface Topography Science Team (OSTST), jointly led by NOAA, NASA, EUMETSAT & CNES, will be the focal point. Sea Level Climate Data Records

4 Iconic Climate Time Series Ocean Climate Observation 7th Annual System Review Silver Spring, Maryland 27–29 October 2010 Global Mean Sea Level Anomaly CO 2 at Mauna Loa

5 The Challenge Ocean Climate Observation 7th Annual System Review Silver Spring, Maryland 27–29 October 2010 ? Ensemble mean steric sea level change (m), wrt , from 12 AR4 models. (Yin et al., JCLIM, 2010) TOPEX/Jason sea level trends (steric & eustatic) 1992 to 2010

6 Sea Level Budget SL total = SL steric + SL mass Total sea level Tide gauge calibration shows offset November 2009 Trends in coastal/shallow water are significantly larger than global sea level rise Steric sea level Argo coverage and pressure sensor issues Ocean mass Differences depending on processing center Glacial isostatic adjustment models

7 Tide gauge calibration Mitchum tide gauge calibration “Single mission” TX/J1/J2 combination calibration Jason-2 ~1 cm offset in November 2009?

8 Recent drift/offset in all altimeters Apparent drifts/offsets in the altimeter — tide gauge residuals for Jason-1, Jason-2, and Envisat in late (November) 2009.

9 No offset in Jason-2 sea level Jason-2 MSL residuals after removing trend, annual, semi-annual, and 59-day terms

10 Possible causes of offset/drift Common to all altimeter calibrations Tide gauges Instrument and datum shifts Vertical land motion Meteorological fields Dry troposphere Inverted barometer correction is not applied for calibration Reference frame Independent causes Wet troposphere

11 Earthquakes near gauges Two relatively large earthquakes struck near gauges at roughly the time of the offset M 8.1, Samoa, 29 September 2009 M 7.3, 100 km, Suva, Fiji, 9 November 2009 M 6.8, 135 km, Nuku'Alofa, Tonga, 24 November GPS vertical motion at Pago Pago SOPAC GPS vertical solutions for Pago Pago show large post-seismic motion opposite of the long-term trend

12 Contributions to offset from gauges Contribution to Jason-2 offset from individual tide gauges weighted differences in mean bias for Nov ± 5 months Pago The offset is seen by the entire tide gauge network

13 Trends in sea level 20 th century rate of sea level rise: 1.7 ± 0.3 mm/yr Rate during altimetry era (1992–2010): 3.3 ± 0.4 mm/yr (when corrected for GIA effect of +0.3 mm/year)

14 Sea level rise near coasts Since 2002 coastal sea level rise has been significantly larger than global Trends from to Complete Jason coverage area: 2.6 mm/year > 120m depth 2.3 mm/year (sealevel.colorado.edu) > 200 km from the coast 1.9 mm/year (Leuliette & Miller 2009) Trends 2005 – Trends versus distance

15 Ocean mass: geoid change Ocean mass variations observed directly from GRACE have little trend for 2004 – A complete analysis must account for ocean mass changes “masked” by geoid variations from the solid Earth’s response to ice melt since the last ice age (Glacial Isostatic Adjustment, GIA) Published results differ more than forcing uncertainty (~20%) 15 Peltier (2004, 2009) +1.9 mm/year Paulson et al. (2007), Tamisiea (2010) +1.0 mm/year

16 Budget results Trend (mm/year) Steric (Argo)0.6 ± 0.4 Mass (GRACE, Paulson GIA)0.9 ± 0.3 Mass (GRACE, Peltier GIA)1.8 ± 0.3 Steric + mass (Paulson GIA)1.5 ± 0.4 Steric + mass (Peltier GIA)2.4 ± 0.4 Total sea level (Jason-1/2)1.6 ± 0.8 Trends for Components of Sea Level Rise and Total Sea Level (2004 – )

17 Discussion While the 6-year “global” budget can be closed within 90% confidence intervals, “global” excludes > 66°, 900 m depth (Argo) Total sea level Tide gauge calibration issue needs to be resolved to ensure the integrity of the sea level CDR Steric sea level Global analyses are preliminary until pressure drift issues are resolved Ocean mass Consensus on GIA correction: Paulson, et al. (2007) and Tamisiea (2010) are appropriate for ocean mass trends NASA has included the rapid follow-on to GRACE in its budget for a start in FY2011 with launch by 2016 Heavily focused on maintaining data continuity from GRACE and minimizing any data gap after GRACE. Ocean Climate Observation 7th Annual System Review Silver Spring, Maryland 27–29 October 2010