mass and volume contribution to twentieth-century global sea level rise
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Mass and Volume Contribution to Twentieth-century Global Sea Level Rise. L. Miller & B. C. Douglas. Nature vol. 428, 2004. Could water world really happen?. Interaction of temperature change with environmental system. Greenland Ice Sheet 7m GSLR. Antarctic+ GLIS 80m GSLR. - PowerPoint PPT PresentationTRANSCRIPT
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Mass and Volume Contribution to Twentieth-century Global
Sea Level Rise
L. Miller & B. C. Douglas
Nature vol. 428, 2004
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Could water world really happen?
Interaction of temperature change with environmental system
Water held in glaciers and small ice caps!!
Greenland Ice Sheet7m GSLR
Antarctic+ GLIS80m GSLR
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But by how much ?
1. Volume Change (Total Steric Sea Level, TSSL)
2. Mass Change (Eustatic change)
Exchange of water with atmosphere and continents
Temperature and salinity variations
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Gauge Data
Total Steric Changes +Eustatic Changes
Isostatic Changes
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Dynamic Height
Depth difference between two surfaces of constant pressure and gravity.
It is derived from hydrographic data (T, S, P)Ocean General Circulation Models (OGCM)
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Different Approaches
Yearly average trend 1993-98 (3.2 + 0.2 mm/yr)TSC (temperature) (0-500m) 1993-98 (3.1 + 0.4mm/yr)Residual sea level (0.2 + 0.2 mm/yr)
5 year data trend
Topex/ Poseidon data from 1993-2001 (Cabanes et al., 2001)
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*Global mean TSC (0-3000m) (0.5 + 0.05 mm/yr)*Pseudo global mean TSC using data of 25 gauge sites (1.4 + 0.2 mm/yr)*PSMSL record at 25 tide gauge sites (1.6+0.15 mm/yr)
*TSSL= 0.55 + 0.07 mm/yr*HSC 0.05 + 0.02 mm/yr
*470 + 170 km3/yr fresh water*Mass increase 1.35+0.5 mm/yr
(Antonov et al., 2002)
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3rd IPCC report (2001)
IPCC adopted best estimates = 1.5 + 0.5 mm/yr
TSC = 0.7 mm/yr
CG = 0.2-0.4 mm/yr
MC = -0.2-0.6 mm/yr
TWS = -1.1- 0.4 mm/yr Sum = -0.8 –2.2 mm/yrAvg = 0.7 mm/yr
0
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Comparison of hydrographic and tide gauge measured sea level change in the
Eastern Pacific
TSSL = 0.5 mm/yrGauge data = 2 mm/yr
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Local comparison
a. 0.5 mm/yr
c. 0.9 mm/yrGauge data = 1.7 mm/yr
b. 0.3 mm/yr
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Regional comparison in the Eastern N. Atlantic
TSSL = 0.2 mm/yr
Gauge data = 2.1 &
1.9 mm/yr
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Regional comparison in the Western N. Atlantic
Gauge data =1.9 mm/yr
Cabanes etal., 20018 sites = 0.5 mm/yr1 site = 6.7 mm/yr (NA)Avg = 1.2 mm/yr
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Conclusions
*Overall gauge data = 1.5- 2.0 mm/yr GSLR for 20th century
Hydrographic data = 0.5 mm/yr
Mass Increase due to freshening = 1.4 mm/yr
* Satellite data = 2.5 mm/yr (1993-2003) Decadal data !!
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Ocean freshening, sea level rising, sea ice meltingP. Wadhams, W. Munk(GRL., Vol. 31, 2004)
Arctic Sea Ice melting = (625 + 125) Km3/yr
Antarctic Ice thickening = (90 + 3) Km3/yr
Volume of fresh water = (325 + 105) Km3/yr
GSLR = mass + volume 0.6 + 0.5 = 1.1 mm/yr
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Thanks
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Total steric sea level change
1.Thermosteric change (TC)
2. Halosteric change (SC)
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Mass and Volume
L. Miller & B. C. Douglas
Nature vol. 428 2004