sustained ocean observations from merchant marine vessels a proposal as you know, the merchant...
TRANSCRIPT
SUSTAINED OCEAN OBSERVATIONS FROM MERCHANT MARINE VESSELS
A proposal As you know, the Merchant Marine has a presence on the high
seas second to none. Analogous to satellites with instrumentation for monitoring the atmosphere and ocean
surface, these vessels could serve as ‘orbiting’ platforms for monitoring the interior of the ocean. While we do so to a limited
extent today, with instrumentation and data management techniques designed and optimized for these platforms we
could open up an entirely new dimension to ocean observation. The following material was presented to the US NSF last year. They suggested we contact SCOR who in turn liked the idea
very much, but felt it would be wise to get JCOMM’s view and input first, hence this presentation.
This figure shows routes engaged at some level of XBT sampling (today’s VOS work). But suppose these vessels could measure currents, obtain temperature
and salinity profiles, measure biomass, monitor water quality and optical properties continuously along their
routes automatically with no observer onboard. Here are a few examples of what’s possible today.
The Nuka Arctica operates on a 3-week schedule
between Greenland and Denmark. The ship has a draft of 8 m and in-situ
biomass is so rich that the ADCP gets good returns to
400 m.
Operated by the University of Bergen.
The ship is equipped with TSG, XBT and
total CO2 systems. DMI also releases balloons from a container.
A typical crossing from Cape Farewell to Denmark.
Very substantial
eddy activity.
Single or sparse sections like this tell us nothing about
the mean circulation and its change over
time.
P. Jaccard, UiB
But using 33 sections Øyvind
Knutsen (UiB) has resolved the flows
around the Reykjanes Ridge in great detail. Note the double flow north, a fine-
structure feature in the mean field which sparse
sampling and/or low-resolution
techniques can’t capture. Narrow pipelines indeed,
very likely a consequence of the ridge topography.
The 150kHz ADCP-equipped Oleander
measures upper ocean currents to ~250m in GS.
The 75kHz system reaches to ~600m.
The Oleander: 1992 to present
Example of a good weather (no bubbles)
ADCP section. The data are uploaded by wireless internet when the vessel docks in Port Elisabeth. We are striving to serve the final product within a
few days.
When viewed this way the GS appears to be quite ‘stiff’. It can be shown
that the exponentials
reflect uniform potential
vorticity with a jump at the
velocity maximum.
THE GULF STREAM IN NATURAL COORDINATES
The dots in the figure include all time scales, tidal, inertial, meandering, seasonal and
interannual. The Oleander program is particularly interested in long-term trends:
The red lines highlight the
GS, Slope and Sargasso Sea
transports over the 11 years.
Integration of velocities across the ship track gives transport in the Slope Sea, Gulf Stream and Sargasso
Seas as a function of time.
These figures show that we could measure transports across whole oceans
at many latitudes.
Mean along and onshore currents in the Slope Sea (after removal of WCRs)
based on 282 ADCP sections. These both
seasonal and interannual variations
superimposed as mentioned earlier. Note the small yet clearly identifiable
mean velocities, with fine structure in both
the vertical and horizontal.
0.4 Sv2.5 Sv
Flagg et al.
Igor Belkin
This figure showing
probability of finding a front
at the surface is a stark
reminder of the richness of fine-structure in the
ocean. The radius of
deformation is only O(5-40)
km. This is the scale we need to resolve in
order to understand the dynamics of the
ocean.
The above activities have depended very heavily upon on individual efforts to adapt existing instrumentation to the
industrial environment of the Merchant Marine. This is fine, but
What we really need is instrumentation that operates without the need for any human presence, to operate
automatically just as with satellite instrumentation. I have no doubt that as we come to recognize what the Merchant Marine can do for ocean observation, we will start to dream
about other variables to add to the measurement suite.
Here are a few examples:
The ADCPis a well-established technology. No reason why it can’t reach deeper working at lower frequencies.
The acoustic correlation current profiler (ACCP) towed behind the vessel is possible.
Tracking a precisely timed acoustic BT using a small baseline set of hydrophones mounted on the bottom of the ship.
Acoustic thermometry from the surface using fish and other nekton as scatterers.
Brooke Ocean Moving Vessel
ProfilerCTD, Chl, light,
small volume water sampling
Their top model can profile to 800 m at 12
Kts. A technician would be required, but
whole system could reside in a container.
A common thread through the entire discussion is repeat sampling in the
horizontal - the most inaccessible and costly dimension in Oceanography. This explains why Satellite Oceanography has been so
phenomenally successful - besides its temporal and spatial coverage also its high
horizontal resolution.
But the piecemeal way we work with the Merchant Marine today makes it all but
impossible to develop a systems approach to the study of the subsurface ocean. We need to develop a new approach or paradigm for working with the Merchant Marine. It seems
to me we should think in terms of a deliberate partnership - something along the following
lines:
Merchant Marine Industry
Prepare vessels at construction time for future
programsIdentify routes, works closely
with OSC to maintain continuity
Ocean Observing Community
Helps develop new scienceIn charge of data flow,
processing, distribution, analysis, assimilation
Trains future scientists and engineers
Instrumentation Industry
Define, develop, and certify new instrument
conceptsUnderstand vessels for
optimal instrument performance and
reliability
Ocean Space Center(s)Leads the development of cutting-edge science and
engineering for ocean space observing systems
Perhaps modeled after
an ESA or NASA
Merchant Marine Industry
Prepare vessels at construction time for future
programsIdentify routes, works closely
with ISC to maintain continuity
Ocean Observing Community
Helps develop new scienceIn charge of data flow,
processing, distribution, analysis, assimilation
Trains future scientists and engineers
Instrumentation Industry
Define, develop, and certify new instrument
conceptsUnderstand vessels for
optimal instrument performance and
reliability
Ocean Space Center(s)Leads the development of cutting-edge science and
engineering for inner space observing systems
Since meeting with NSF last year my
thinking has converged towards something like this
diagram. It is ambitious for sure,
but this may be what we need in
order to break out of our incremental approach to ocean observation and working with the
Merchant Marine?!
Perhaps modeled after
an ESA or NASA
Your reactions, thoughts and suggestions on the above would be much appreciated.
Thank you!