Monitoring the Global Sea Level Rise Budget with Jason, Argo and GRACE Observations
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Transcript of Monitoring the Global Sea Level Rise Budget with Jason, Argo and GRACE Observations
Monitoring the Global Sea Level Rise Budget with Jason, Argo
and GRACE ObservationsEric Leuliette and Laury Miller
NOAA/Laboratory for Satellite Altimetry
Ocean Climate Observation 7th Annual System Review • Silver Spring, Maryland • 27–29 October 2010
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Fourth levelFifth 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
4Ocean Climate Observation 7th Annual System Review • Silver Spring, Maryland• 27–29 October 2010
Iconic Climate Time Series Global Mean Sea Level Anomaly
CO2 at Mauna Loa
5Ocean Climate Observation 7th Annual System Review • Silver Spring, Maryland• 27–29 October 2010
The Challenge
?Ensemble mean steric sea level change (m), 2091-2100 wrt 1980-2000, from 12 AR4 models. (Yin et al., JCLIM, 2010)
TOPEX/Jason sea level trends (steric & eustatic) 1992 to 2010
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Sea Level BudgetSLtotal = SLsteric + SLmass
Total sea level• Tide gauge calibration shows offset November 2009• Trends in coastal/shallow water are significantly larger
than global sea level riseSteric sea level• Argo coverage and pressure sensor issuesOcean mass• Differences depending on processing center• Glacial isostatic adjustment models
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Tide gauge calibrationMitchum tide gauge calibration“Single mission” TX/J1/J2
combination calibration
Jason-2 ~1 cmoffset in
November 2009?
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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.
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No offset in Jason-2 sea levelJason-2 MSL residuals after removing trend, annual,
semi-annual, and 59-day terms
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Possible causes of offset/driftCommon to all altimeter calibrationsTide 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
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Earthquakes near gaugesTwo 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 2009.
GPS vertical motion at Pago Pago
SOPAC GPS vertical solutions for Pago Pago show large post-seismic motion opposite of the long-term trend
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Contributions to offset from gaugesContribution to Jason-2 offset from individual tide gauges• weighted differences in mean bias for Nov. 2009 ± 5 months
Pago Pago
The offset is seen by the entire tide gauge
network
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Trends in sea level20th century rate of sea level rise: 1.7 ± 0.3 mm/yrRate during altimetry era (1992–2010): 3.3 ± 0.4 mm/yr
• (when corrected for GIA effect of +0.3 mm/year)
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Sea level rise near coastsSince 2002 coastal sea level rise has been significantly
larger than globalTrends from 2005.5 to 2010.5• 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 – 2010.5 Trends versus distance
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Ocean mass: geoid changeOcean mass variations observed directly from GRACE have little trend for
2004 – 2010.
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%)
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Peltier (2004, 2009)+1.9 mm/year
Paulson et al. (2007), Tamisiea (2010)+1.0 mm/year
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Budget results
Trend (mm/year)
Steric (Argo) 0.6 ± 0.4Mass (GRACE, Paulson GIA) 0.9 ± 0.3Mass (GRACE, Peltier GIA) 1.8 ± 0.3Steric + mass (Paulson GIA) 1.5 ± 0.4Steric + mass (Peltier GIA) 2.4 ± 0.4Total sea level (Jason-1/2) 1.6 ± 0.8
Trends for Components of Sea Level Rise and Total Sea Level (2004 – 2010.25)
17Ocean Climate Observation 7th Annual System Review • Silver Spring, Maryland• 27–29 October 2010
DiscussionWhile the 6-year “global” budget can be closed within 90%
confidence intervals, “global” excludes > 66°, < 200 km from coasts, and > 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.