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!