Download sustained ocean observations from merchant marine vessels

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 insitu biomass is so rich that the
ADCP gets good returns to 400
m.
The ship is
equipped with
TSG, XBT and
total CO2
systems. DMI
also releases
balloons from a
container.
Operated by the University of Bergen.
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 lowresolution techniques
can’t capture. Narrow
pipelines indeed, very
likely a consequence
of the ridge
topography.
The Oleander: 1992 to present
The 150kHz ADCP-equipped
Oleander measures upper
ocean currents to ~250m in
GS. The 75kHz system
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.
THE GULF STREAM IN NATURAL COORDINATES
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 dots in the figure include all time scales, tidal,
inertial, meandering, seasonal and interannual. The
Oleander program is particularly interested in longterm trends:
Integration of velocities across the ship track gives transport
in the Slope Sea, Gulf Stream and Sargasso Seas as a
function of time.
The red lines
highlight the GS,
Slope and
Sargasso Sea
transports over
the 11 years.
These figures show that we could measure
transports across whole oceans at many
0.4 Sv
2.5 Sv
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
Flagg et al.
vertical and horizontal.
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 Igor Belkin
understand the
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
ADCP
is a wellestablished
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 Profiler
CTD, 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
Merchant Marine Industry
Prepare vessels at construction
time for future programs
Identify routes, works closely with
OSC to maintain continuity
Ocean Space Center(s)
Leads the development of cuttingedge science and engineering for
ocean space observing systems
Ocean Observing
Community
Helps develop new science
In charge of data flow, processing,
distribution, analysis, assimilation
Trains future scientists and
engineers
Perhaps modeled
after
an ESA or NASA
Instrumentation Industry
Define, develop, and certify
new instrument concepts
Understand vessels for
optimal instrument
performance and reliability
Since meeting with
Merchant Marine Industry
NSF last year my
Prepare vessels at construction
thinking has converged
time for future programs
towards something like
Identify routes, works closely with
ISC to maintain continuity
this diagram. It is
ambitious for sure, but
this may be what we
need in order to break
Ocean Space Center(s)
Leads the development of cuttingout of our incremental
edge science and engineering for
Perhaps modeled
approach to ocean
inner space observing systems
after
observation and
an ESA or NASA
working with the
Merchant Marine?!
Instrumentation Industry
Ocean Observing
Define, develop, and certify
Community
Helps develop new science
In charge of data flow, processing,
distribution, analysis, assimilation
Trains future scientists and
engineers
new instrument concepts
Understand vessels for
optimal instrument
performance and reliability
Your reactions, thoughts and suggestions on the above
would be much appreciated.
Thank you!