THE PROBLEM OF STUDYING THE PROBLEM OF THE OCEAN IN CLIMATE

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THE PROBLEM OF STUDYING THE PROBLEM OF THE OCEAN
IN CLIMATE Carl Wunsch Ocean Sciences Meeting,
Orlando March 2008
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We have collectively moved from an era in which
the ocean was generally regarded as nearly
unchanging over decades to one in which the
emphasis is on its changes. Further shifted from
delineating high frequency phenomena such as
internal waves and mesoscale eddies to a focus on
interannual, decadal, and longer period
shifts. Our infrastructure, and to a large
degree, human society, are poorly structured to
deal with multi-decadal and longer time scales
(an inter-generational problem).
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Example of an oceanographic study. Curry
McCartney, 2001. Phenomenological time scales
match or exceed the data duration
The system is very noisy and it is a truism of
science that one must observe phenomena so as to
clearly delineate the time scales of change and
of energy. Thus multi-decadal and longer
observations are required and there is no
escaping the conclusion. No one would advocate
the study of one-second period surface waves for
only a few seconds. That is what we are doing
with decadal ocean variability.
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Note the extreme spatial variability. Dynamics
tells us different regions behave differently.
Anomaly of surface elevation, Jan 2005, 25cm
A year of current meter data, day-by-day from a
quiet part of the ocean Sargasso Sea, 37N, 42W.
How many years to get stable statistics?
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Cazenave and Nerem, 2004, trends in mean sea
level, 13 years, mm/y. Mean of 2.8mm/y removed.
Such patterns have very serious societal
consequences.
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Cessi et al., 2004. Theory all implies the same
problem Example Time in years for a North
Atlantic disturbance to penetrate the world
ocean (sea level). Many decades are required for
its evolution and many more required to fully
observe it.
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Can one possibly understand this
Without understanding this?
Character of the motions is position dependent.
Hogg Owens, DSR, 1999
A lot of physics lies between these observed
motions---requiring years of study---and the
Wüstian arrows (which have only direction).
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Nansen bottles/reversing thermometers about
1860-1965
STD/CTD about 1965- present
Maintaining calibration over decades is one
of the most difficult of all technical problems,
as are decisions concerning technology
replacement.
SeaOs about 2003-present
Whats next?
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• All the science says that observations must be
• Global
• Time continuous
• Of open-ended duration
• Continuously calibrated
• Continuously evaluated for scientific benefit

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• Open ended, or operational, systems face major
  challenges.
• Sustained calibration need
• Obsolescence of the technology is inexorable
• Apparently higher priority, short-term budget
  requirements always appear.
• Low frequency signals require great patience
• Technicians, who are not the end-users of the
  data, have a hard time
• maintaining continuity and quality control
• (6) Sometimes the observations, when better
  understood, are no longer regarded as high
  priority and one might best be discontinued---the
  possibility has always to be considered, but a
  threat to jobs and careers.
• (7) Satellite systems also need to be maintained,
  to sample often enough (enough instruments to
  avoid serious aliasing ), global spatial
  coverage.
• And that technology also evolves. Need
  overlaps and calibration. A complicated
  scientific problem in its own right.
• (8) A powerful tendency (witness US and UK
  obsession with the North Atlantic)
• for scientists to focus on regions. But
  climate is global and omission of major regions
  of observation will drastically curtail future
  understanding.

How do you do this?
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None of this is easily consistent with academic
or other time scales. It becomes a
scientific-engineering-societal commitment. Is
there some way to do this, or is it beyond the
capacity of human society? Usual initial
reaction is to point at the meteorological
experience---a short-term set of problems leading
to long-term records. Unhappily, the parallel is
nither apt nor encouraging severe
difficulties with calibration. Focus on
short-term forecasting as opposed to estimation
of the state. Oceanographic and general climate
variations over years, generally without ongoing
constituencies to sustain the observation
systems.
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Example of the Difficulty The Bermuda
Observatory of Henry Stommel Tide gauge in Ferry
Reach (Bermuda Biological Station) Cable down
island slope to measure temperature and bottom
pressure (and plug in any new instrument as
available) Radio tracking of surface
drifters Hydrographic station (Panulirus Station
?Station S) Only the hydrographic station
continues. Stommel himself abandoned the
observatory idea within a few years.
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Hydrography was/is subject to aliasing, bad
weather, ship breakdowns, equipment loss, quality
control problems. Cable connections were hard to
maintain. On-the-bottom-of-a-slope temperatures
on a large island require considerable theory to
interpret. Drifter measurements proved
uninterpretable (false mean flows from
rectification. They repose in published
obscurity. H. Stommel, Autobiography. They
didnt know about the eddy-field.) Tide gauge
was reliable only during the lifetime of Colonel
Stevens for whom it was a retirement hobby. After
take-over by NOAA, record was soon
interrupted. Center of the Sargasso Sea is not
representative at low frequencies of the ocean as
a whole (or at least it is not obviously so).
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Its noisy. Broken up, aliased and hard to use.
A crisis every 3-5 years when funding came up for
renewal You have 10 years of data isnt that
sufficient?.
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Global coverage by moored current meters over
full water column, circa 1975-1995. Incoherent.
Not cheap. Patience was required. Probably none
is still in maintained.
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Now operational observatory. Upper ocean
coverage only---great missed opportunity. Is the
science community truly engaged?
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Spatial positions/sampling have to be chosen very
carefully if one is not to draw erroneous
conclusions.
from Cabanes, Cazenave and Le Provost, 2001
showed bias of long tide gauge records
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Estimated time to equilibrium at 2000m of a
global surface passive tracer
North Atlantic alone takes hundreds of years to
reach equilibrium.
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All the science points to the conclusion that our
generation(s) will have inadequate data to
solve the ocean-in-climate problem.
Unpalatable, but how to escape the inference? If
the inference is accepted, our problem then
becomes one of laying the foundation for some
future generation to have adequate data. (There
are parallel issues concerning climate model
development and testing that I am omitting here.)
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How does one sustain open-ended measurements and
model scrutiny when the result will be of
greatest interest to future generations? Existing
infrastructure is grossly inadequate to that end.
One needs a multi-decadal, century, open-ended,
view. A few organizations persist for hundreds
to order 1000 years, although the true continuity
of any of them is highly debatable Roman
Catholic and Orthodox Churches, 1000
years European Universities, 900 years US
universities, hundreds of years A handful of
banks, 200 years maximum The Hudsons Bay
Company, 200 years The churches all had schisms,
and near-collapse. The ancient universities
similarly underwent interregna and were generally
founded for now-suppressed religious purposes.
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A strawman plan (see Baker, Schmitt, Wunsch,
2007, Oceanography) later talk by Ray
Schmitt The scarcest asset is the right people.
Need the very best scientists and engineers, but
dont need them full time. Need decadal
commitments and a mechanism for review and
renewal. Carrot Major salary (where an issue),
and research support say 50 of normal salary.
Support for a student and post-doc, or laboratory
funding,. No restriction on the research
pursued.
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In return 30 of time, on average, devoted to
open-ended global observations and/or model
assessments. Would range from lobbying
governments to sustain measurements, routinely
checking calibrations, testing new technologies,
engaging in discussions of technology
replacements, Would NOT be the
observation-funding agency itself---that would
continue to lie with governments. Thirty to
fifty, mid-career, people world-wide. Would form
a kind of senate or parliament which would
maintain a long-term perspective.
Self-perpetuating by consensus. A 10-20 year
commitment. A mechanism for reviewing
individuals activities every 10-15 years. A
globally distributed system with a managerial
focus somewhere in the world.
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Needs an endowment. Something under US1billion
would do it. (Would not be the resource for
funding observations.) Pocket money for some
people Harvard University endowment today is
about US35billion.
Perhaps there is another, better way. Can we get
a dialogue started? Urgent unobserved climate
change is gone forever. Not often can one
identify a true inter-generational problem. This
is one. Is there anything more important we can
do collectively?
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Thank you.