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Toward Closing the (Almost) Globally Averaged Sea Level Budget. Josh K. Willis Jet Propulsion Laboratory California Institute of Technology. Thanks to Don Chambers, Steve Nerem Al Gore John Lyman, Greg Johnson, John Gilson Rush Limbaugh

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slide1

Toward Closing the (Almost) Globally Averaged Sea Level

Budget

Josh K. Willis

Jet Propulsion Laboratory

California Institute of Technology

slide2

Thanks to

Don Chambers, Steve Nerem

Al Gore

John Lyman, Greg Johnson, John Gilson

Rush Limbaugh

Susan Wijffels, Catia Domingues, Paul Barker, Neil White, Ann Gronell, Ken Ridgway, John Church

overview
Overview
  • Motivation (as if you needed any)
  • In case you haven’t heard:

Oceans not cooling!

  • 2003 – 2007 Sea Level Budget
  • Revised Thermal Expansion ’93 – ’07
globally averaged sea level rise
“Globally-Averaged” Sea Level Rise
  • About 20 cm of SLR over the record
  • Obvious acceleration

From Church and White,GRL, 2005

gobally averaged sea level rise

addition of heat

addition of freshwater

Gobally-averaged sea level rise

Total sea level rise

+

=

(roughly)

earth s energy balance

Earth Warms

Earth’s Energy Balance

Balance

is

restored

Atmosphere

Atmosphere

ocean warming global warming
Ocean Warming ≈ Global Warming

from Levitus et al., GRL, 2005

slide9

Earth Warms

Earth’s Energy Balance

To raise Earth’s temperature

The Oceans must warm

slide10

“Recent Ocean Cooling”

~ 6 mm drop in thermosteric sea level

From Lyman et al., GRL, 2006

slide11

My brush with Rush

“Proving again, that they really don’t know much about anything when it comes to climate, climate change and so forth.”

̶ Rush Limbaugh

“To overturn the world economy based on the musings of a few idiot leftist scientists is just stupid, and that’s what Global Warming is all about.” ̶ Rush Limbaugh

slide12

In Situ Data biases: Argo floats

SOLO/FSI floats have a cold bias at depth

a correction to recent cooling
A correction to “recent cooling”

Ocean Heat Content from 2004 to 2006

Removing the bad float data reduces the cooling but does not completely eliminate it.

From Willis et al., JTECH, in press

in situ data biases xbt fall rate errors

Isotherm

Displacement:

Dz =

Tclim – T

dTclim /dz

In situ data biases: XBT fall-rate errors

Comparison of

Isotherm Displacements

XBT/Argo pairs ~12,000

Argo/CTD pairs ~2,000

From Willis et al., JTECH, in press

a correction to recent cooling1
A correction to “recent cooling”

Ocean Heat Content from 2004 to 2006

Another bias:

XBTs are biased warm, which also causes spurious cooling.

From Willis et al., JTECH, in press

time varying bias
Time Varying Bias

Shallow probes

Deep probes

Common time history by profile type suggests manufacturing changes cause time varying bias

From Wijffels et al., JCLIM, in press

revised upper ocean warming
Revised upper ocean warming

From Domingues et al., Nature, 2008

slide18

Mountain Glaciers

(Duygerov & Meier, 2005)

Greenland & Antarctica

(IPCC, AR4, 2007)

0/700 m warming

Deep Warming

(Köhl et al., JPO, 2007)

Terrestrial Storage

(Ngo-Duc et al., GRL, 2005)

Sum of components

Tide gauge reconstruction

The 40-year Sea Level Budget

From Domingues et al., Nature, 2008

toward closing the globally averaged sea level budget on seasonal to interannual time scales

Toward closing the globally averaged sea level budget on seasonal to interannual time scales

Josh K. Willis

joshua.k.willis@jpl.nasa.gov

Jet Propulsion Laboratory

Co-Authors:

Don P. Chambers, R. Steven Nerem

From Willis et al., JGR – Oceans, 2008

globally averaged sea level rise1

addition of heat

addition of freshwater

Globally-averaged sea level rise

Total sea level rise

+

=

(roughly)

Argo

GRACE

Jason

slide21

Argo

  • Argo data only
  • All data with known pressures errors removed.
  • Steric height computed from Argo Temp. & Sal.
  • Monthly objective maps of large scale steric variability.
argo data distribution
Argo data distribution

Mid 2003 is data sparse in Southern Hemisphere

1800 km zonal, 700 km meridional e-folding scale

test of mapping procedure
Test of Mapping Procedure
  • Jason data interpolated to time and location of Argo profiles
  • Mapped using same mapping procedures
  • Compared with full Jason time series

RMS difference: 1.6 mm

slide24

Atmospheric and Ocean models

  • Adjustment for incompressibility
  • Degree 2, order 0 coefficients from SLR
  • Monthly model of geocenter+
  • GIA correction*
  • Land mask
  • ± 66° latitude

± 0.2 mm/yr

± 0.2 mm/yr

+ Swenson et al., JGR-Oceans, submitted.

* Paulson et al., Geophys. J. Int., 2007

mass exchange with high latitudes
Mass exchange with high latitudes

Difference between

total ocean average and ± 66° average

Very small interannual signal

slide26

Jason

  • Jason data only
  • Standard corrections applied (including IB)
  • GIA +0.3 mm/yr [Douglas and Peltier, 2002]
the recent sea level budget
The recent sea level budget

Global Mean Sea Level

Global MSL, no seasonal

Total (Jason)

Total (Jason)

Steric (Argo)

Steric (Argo)

Mass (GRACE)

Mass (GRACE)

sea level budget
Sea Level Budget

Seasonal cycles agree to within random error

4-year trends have discrepancy larger than random error => systematic error remains!

slide30

The recent sea level budget

Total (Jason)

Global MSL, no seasonal cycle, no trend

Removal of trend brings all three estimates into excellent agreement

Steric (Argo)

Mass (GRACE)

RMS difference:

1.6 mm

slide31

4-year Trends in sea level

The recent sea level budget

Jason

General agreement is encouraging

Jason-GRACE

But, difference in S. Hemisphere trends is concerning

Argo

pseudo pair comparison
“Pseudo-pair” comparison

Comparison of Sippican Deep Blue probes with nearby Argo pairs (2004 – 2006), ~12,000

  • Pseudo-pairs give same bias, but have narrower distribution
  • More comprehensive means of test XBT bias because of SSH data availability

From Wijffels et al., JCLIM, in press.

stretching factor by probe type
Stretching factor by probe type

From Wijffels et al.,

J CLIMATE, in press

revised thermosteric sea level
Revised thermosteric sea level

3.2 mm/year

Equivalent to 0.55 W/m2 of radiative imbalance

1.4 mm/year

inferred estimate of mass increase
Inferred estimate of mass increase

Discrepancy with GRACE remains

1.9 mm/year

1.6 mm/year

Slight differences in total SSH

interannual variations in ssh

PDF

Interannual variations in SSH

1-Year average of SSH during

the 1997-98 El Niño

Variations are O(10 cm)

slide39

14 year trend in SSH from AVISO

Global mean: 3.0 mm/yr

slide40

14-year trend in thermosteric

sea level

Combined in situ + altimeter

mean: 1.4 mm/yr

In situ data only

mean: 1.4 mm/yr

slide41

14-year trend in total minus

thermosteric

Combined in situ + altimeter

mean: 1.6 mm/yr

In situ data only

mean: 1.6 mm/yr

slide42

14 year trend in globally averaged temperature

Warming Signal is O(0.15°C)

= 5-10 m in depth

slide43

The Ocean Observing System

Profile distribution for 1993

Profile distribution for 2007

slide44

The Ocean Observing System

No Plan for Measuring

the Deep Oceans!

hydrographic surveys

1999-1985

Hydrographic surveys

From Fukasawa et al., Nature, 2004

hydrographic surveys1

Hydrographic surveys

2006-1984

2006-1991

1991-1984

From Johnson et al., Journal of Climate, 2007

slide47

Conclusions

  • No more ocean cooling!
  • GRACE, Jason & Argo still do not agree
  • Revised thermal expansion:

’93 – ’07: 1.4 mm/yr

=> 1.6 to 1.9 mm/yr mass

  • Deep Ocean Warming remains unmeasured